0001503802--12-31Q1false11http://fasb.org/srt/2025#ChiefExecutiveOfficerMember0001503802us-gaap:RestrictedStockUnitsRSUMember2025-01-012025-03-310001503802kpti:MenariniLicenseAgreementMemberus-gaap:RoyaltyMember2025-01-012025-03-310001503802kpti:TwoThousandTwentyFourWarrantsMember2026-03-310001503802kpti:AmendedTermLoanMember2025-10-012025-10-310001503802kpti:LicenseAgreementsMember2026-01-012026-03-310001503802us-gaap:CommonStockMember2024-12-310001503802us-gaap:FairValueInputsLevel3Memberkpti:ConvertibleNotesDerivativesMember2026-01-012026-03-310001503802us-gaap:SellingGeneralAndAdministrativeExpensesMember2025-01-012025-03-310001503802kpti:TwoThousandTwentyNineNotesMember2026-03-310001503802kpti:TwoThousandTwentyFourWarrantsMember2026-01-012026-03-310001503802us-gaap:RetainedEarningsMember2025-12-310001503802kpti:NewTwoThousandTwentyNineNotesMember2026-01-012026-03-310001503802us-gaap:AdditionalPaidInCapitalMember2025-03-310001503802kpti:TwoThousandTwentyTwoWarrantsMember2025-12-310001503802us-gaap:USGovernmentAgenciesDebtSecuritiesMember2026-03-310001503802us-gaap:DomesticCorporateDebtSecuritiesMember2025-01-012025-12-310001503802kpti:TwoThousandTwentyEightNotesMember2025-10-072025-10-070001503802us-gaap:BaseRateMemberus-gaap:LineOfCreditMember2025-10-012025-10-310001503802kpti:MaytwoThousandTwentyFourWarrantsMembersrt:MaximumMember2026-03-310001503802us-gaap:LicenseAndServiceMemberkpti:AntengeneTherapeuticsLimitedMember2025-01-012025-03-310001503802kpti:AntengeneTherapeuticsLimitedMemberus-gaap:RoyaltyMember2026-01-012026-03-310001503802srt:ScenarioForecastMemberkpti:NewTwoThousandTwentyNineNotesAndTwoThousandTwentyEightNotesMembersrt:MaximumMember2026-10-102026-10-100001503802kpti:TwoThousandTwentySixWarrantsMember2026-03-012026-03-310001503802kpti:MenariniLicenseAgreementMemberus-gaap:LicenseAndServiceMember2026-01-012026-03-310001503802us-gaap:FairValueInputsLevel2Member2026-03-310001503802srt:MinimumMember2025-10-012025-10-310001503802kpti:HealthcareRoyaltyPartnersIvLpMember2024-05-310001503802us-gaap:RetainedEarningsMember2026-01-012026-03-310001503802kpti:AmendedTermLoanMember2026-01-012026-03-310001503802srt:ScenarioForecastMemberkpti:NewTwoThousandTwentyNineNotesAndTwoThousandTwentyEightNotesMember2026-10-112026-10-110001503802kpti:NewTwoThousandTwentyNineNotesMemberus-gaap:ConvertibleDebtMember2026-03-310001503802srt:MaximumMember2026-02-180001503802us-gaap:WarrantMember2026-01-012026-03-310001503802kpti:TwoThousandTwentyFourWarrantsMember2026-01-012026-03-310001503802kpti:SecuredOvernightFinancingRateMemberus-gaap:LineOfCreditMember2026-01-012026-03-310001503802kpti:TermLoanAndAmendedTermLoanMember2026-01-012026-03-310001503802kpti:TwoThousandTwentySixWarrantsMember2025-12-310001503802us-gaap:ProductMember2026-03-310001503802kpti:MaytwoThousandTwentyFourWarrantsMember2025-10-012025-10-310001503802srt:MaximumMember2025-10-012025-10-310001503802kpti:MenariniLicenseAgreementMemberus-gaap:LicenseAndServiceMember2025-01-012025-03-310001503802kpti:SixPercentageSecuredConvertibleSeniorNotesDueTwoThousandTwentyNineMemberkpti:HealthcareRoyaltyPartnersIvLpMember2024-05-310001503802kpti:TermLoanMember2024-05-310001503802kpti:NinePercentageSecuredConvertibleSeniorNotesDueTwoThousandTwentyEightMember2026-01-012026-03-310001503802kpti:MenariniLicenseAgreementMember2025-01-012025-03-310001503802us-gaap:AdditionalPaidInCapitalMember2025-12-310001503802us-gaap:FairValueInputsLevel3Memberkpti:ConvertibleNotesDerivativesMember2026-03-310001503802kpti:NewTwoThousandTwentyNineNotesMemberus-gaap:ConvertibleDebtMember2026-01-012026-03-310001503802us-gaap:CommonStockMemberkpti:OpenMarketSaleAgreementMemberkpti:JefferiesLLCMember2026-01-012026-03-310001503802kpti:TwoThousandTwentyFiveNotesMember2025-10-012025-10-310001503802us-gaap:CommonStockMember2025-01-012025-03-310001503802us-gaap:FairValueInputsLevel3Memberkpti:ConvertibleNotesDerivativesMember2025-12-310001503802us-gaap:BaseRateMemberus-gaap:LineOfCreditMember2026-01-012026-03-310001503802us-gaap:USGovernmentAgenciesDebtSecuritiesMemberus-gaap:FairValueInputsLevel2Member2026-03-310001503802kpti:TwoThousandTwentyEightNotesMember2025-10-070001503802srt:MinimumMemberkpti:NewTwoThousandTwentyNineNotesAndTwoThousandTwentyEightNotesMember2026-03-310001503802kpti:LicenseAndOtherMember2025-01-012025-03-310001503802us-gaap:SubsequentEventMemberus-gaap:LineOfCreditMember2026-04-012026-04-010001503802us-gaap:AccumulatedOtherComprehensiveIncomeMember2025-12-310001503802us-gaap:FairValueInputsLevel1Member2025-12-310001503802kpti:PreFundedWarrantsMember2025-10-310001503802us-gaap:LicenseAndServiceMemberkpti:AccountsReceivable1Member2025-01-012025-12-310001503802us-gaap:FairValueInputsLevel3Memberkpti:DeferredRoyaltyObligationMember2026-03-310001503802kpti:TwoThousandTwentyNineNotesMemberus-gaap:ConvertibleDebtMember2025-10-072025-10-0700015038022025-12-310001503802kpti:OpenMarketSaleAgreementMembersrt:MaximumMemberkpti:JefferiesLLCMember2023-02-280001503802us-gaap:RetainedEarningsMember2026-03-310001503802kpti:TermLoanAndAmendedTermLoanMember2025-01-012025-03-310001503802us-gaap:OperatingSegmentsMemberus-gaap:ProductMember2026-01-012026-03-310001503802kpti:TwoThousandTwentyFourWarrantsMember2025-12-310001503802us-gaap:CommonStockMember2025-03-310001503802kpti:TwoThousandTwentyNineNotesMember2024-05-130001503802us-gaap:AccumulatedOtherComprehensiveIncomeMember2025-01-012025-03-310001503802kpti:TwoThousandTwentyTwoWarrantsMemberus-gaap:PrivatePlacementMember2022-12-052022-12-050001503802us-gaap:StockOptionMember2025-01-012025-03-310001503802kpti:SecuritiesPurchaseAgreementMemberus-gaap:PrivatePlacementMember2026-03-240001503802kpti:SecuredOvernightFinancingRateMemberus-gaap:LineOfCreditMember2025-10-012025-10-310001503802srt:ScenarioForecastMember2025-10-102026-10-100001503802kpti:NewTwoThousandTwentyNineNotesAndTwoThousandTwentyEightNotesMembersrt:MaximumMember2026-03-310001503802kpti:TwoThousandTwentyEightNotesMember2026-03-310001503802us-gaap:LicenseAndServiceMemberkpti:AntengeneTherapeuticsLimitedMember2026-01-012026-03-310001503802kpti:CreditAgreementAndTermLoanMemberus-gaap:LineOfCreditMember2024-05-080001503802us-gaap:FairValueInputsLevel1Member2026-03-310001503802kpti:TwoThousandTwentyEightNotesMember2026-01-012026-03-310001503802srt:MinimumMember2026-02-180001503802us-gaap:CommonStockMember2025-12-310001503802kpti:PreFundedWarrantsMember2025-12-310001503802kpti:TwoThousandTwentyFivePlacementWarrantsMember2025-12-310001503802kpti:TwoThousandTwentyFiveNotesMemberkpti:TwoThousandTwentyFiveWarrantsMember2025-10-310001503802kpti:NewTwoThousandTwentyNineNotesAndTwoThousandTwentyEightNotesMember2026-01-012026-03-310001503802srt:MaximumMemberkpti:MaytwoThousandTwentyFourWarrantsMember2024-05-130001503802kpti:KKRCoIncMemberkpti:RevenueInterestFinancingAgreementMember2026-01-012026-03-310001503802srt:MaximumMember2026-03-012026-03-310001503802kpti:ThreePercentageUnsecuredConvertibleSeniorNotesDueTwoThousandTwentyFiveMember2026-01-012026-03-310001503802kpti:AmendedTermLoanMember2025-12-310001503802kpti:TwoThousandTwentyFivePlacementWarrantsMember2026-01-012026-03-310001503802us-gaap:CostOfSalesMember2026-01-012026-03-310001503802us-gaap:FairValueInputsLevel3Memberkpti:LiabilityClassifiedWarrantsMember2026-01-012026-03-310001503802us-gaap:AccumulatedOtherComprehensiveIncomeMember2025-03-310001503802kpti:TwoThousandTwentyFiveConvertibleNotesMember2025-01-012025-03-310001503802us-gaap:RetainedEarningsMember2024-12-310001503802us-gaap:CommonStockMember2026-03-310001503802kpti:SixPercentageSecuredConvertibleSeniorNotesDueTwoThousandTwentyNineMember2024-05-310001503802kpti:TwoThousandTwentyNineConvertableNotesMember2025-01-012025-03-310001503802us-gaap:AdditionalPaidInCapitalMember2026-03-310001503802kpti:TermLoanAndAmendedTermLoanMember2026-01-012026-03-310001503802us-gaap:PrivatePlacementMemberkpti:TwoThousandTwentyFivePlacementWarrantsMember2025-10-310001503802us-gaap:LicenseAndServiceMemberkpti:AccountsReceivable1Member2026-01-012026-03-310001503802us-gaap:CommonStockMemberkpti:OpenMarketSaleAgreementMemberkpti:JefferiesLLCMember2025-01-012025-03-310001503802us-gaap:ProductMember2026-01-012026-03-310001503802kpti:RevenueInterestFinancingAgreementMember2026-03-310001503802us-gaap:CommonStockMemberkpti:TwoThousandTwentyFiveNotesMember2025-10-310001503802kpti:TwoThousandTwentyFiveWarrantsMember2025-10-310001503802kpti:PreFundedWarrantsMember2026-01-012026-03-310001503802kpti:NinePercentageSecuredConvertibleSeniorNotesDueTwoThousandTwentyNineMember2026-01-012026-03-310001503802kpti:PreFundedWarrantsMemberkpti:TwoThousandTwentyFiveNotesMember2025-10-310001503802kpti:MaytwoThousandTwentyFourWarrantsMember2024-05-080001503802us-gaap:ProductMember2025-01-012025-03-310001503802us-gaap:MoneyMarketFundsMemberus-gaap:FairValueInputsLevel1Member2026-03-310001503802kpti:OpenMarketSaleAgreementMembersrt:MaximumMemberkpti:JefferiesLLCMember2026-01-012026-03-310001503802kpti:RevenueInterestAgreementAndAmendedRevenueInterestAgreementMemberkpti:HealthcareRoyaltyPartnersIvLpMember2024-05-310001503802us-gaap:AccumulatedOtherComprehensiveIncomeMember2024-12-310001503802kpti:TwoThousandTwentyNineNotesMemberus-gaap:ConvertibleDebtMember2024-05-132024-05-130001503802srt:MaximumMemberkpti:MaytwoThousandTwentyFourWarrantsMember2024-05-310001503802kpti:EmbeddedDerivativesOnTwoThousandTwentyEightNotesMember2026-01-012026-03-310001503802kpti:SixPercentageSecuredConvertibleSeniorNotesDueTwoThousandTwentyNineMember2026-01-012026-03-310001503802us-gaap:DomesticCorporateDebtSecuritiesMember2025-12-310001503802kpti:AmendedCreditAgreementMember2025-10-012025-10-310001503802kpti:NewTwoThousandTwentyNineNotesMember2025-10-070001503802kpti:TwoThousandTwentyFiveNotesMemberus-gaap:ConvertibleDebtMember2024-05-132024-05-130001503802kpti:TwoThousandTwentyNineNotesMemberus-gaap:ConvertibleDebtMember2026-03-310001503802kpti:SecuritiesPurchaseAgreementMemberkpti:TwoThousandTwentySixWarrantsMemberus-gaap:PrivatePlacementMember2026-03-240001503802us-gaap:FairValueInputsLevel2Member2025-12-310001503802us-gaap:LicenseAndServiceMember2026-01-012026-03-3100015038022024-05-012024-05-310001503802us-gaap:CommonStockMemberkpti:TwoThousandTwentyFiveNotesMember2025-10-300001503802kpti:TwoThousandTwentySixWarrantsMember2026-03-310001503802us-gaap:RetainedEarningsMember2025-03-310001503802kpti:TwoThousandTwentyFiveWarrantsMember2026-01-012026-03-310001503802kpti:TwoThousandTwentyNineNotesMemberus-gaap:ConvertibleDebtMember2026-01-012026-03-310001503802us-gaap:USGovernmentAgenciesDebtSecuritiesMemberus-gaap:FairValueInputsLevel2Member2025-12-310001503802kpti:NewTwoThousandTwentyNineNotesMember2025-10-072025-10-070001503802kpti:TwoThousandTwentyTwoWarrantsMemberus-gaap:PrivatePlacementMember2022-12-050001503802kpti:MaytwoThousandTwentyFourWarrantsMember2025-10-310001503802kpti:TwoThousandTwentyFiveWarrantsMember2026-03-310001503802kpti:NewTwoThousandTwentyNineNotesMember2025-01-012025-03-3100015038022026-01-012026-03-310001503802kpti:RevenueInterestAgreementAndAmendedRevenueInterestAgreementMemberkpti:HealthcareRoyaltyPartnersIvLpMember2026-03-310001503802kpti:TwoThousandTwentyNineNotesMember2025-10-070001503802kpti:NewTwoThousandTwentyNineNotesMember2025-12-310001503802us-gaap:ResearchAndDevelopmentExpenseMember2025-01-012025-03-310001503802us-gaap:AccumulatedOtherComprehensiveIncomeMember2026-03-310001503802us-gaap:MoneyMarketFundsMemberus-gaap:FairValueInputsLevel1Member2025-12-310001503802kpti:MaytwoThousandTwentyFourWarrantsMember2026-01-012026-03-310001503802kpti:NewTwoThousandTwentyNineNotesAndTwoThousandTwentyNineNotesMember2025-01-012025-03-310001503802us-gaap:StockOptionMember2026-01-012026-03-310001503802kpti:SecuritiesPurchaseAgreementMemberkpti:PreFundedWarrantsMembersrt:MaximumMemberus-gaap:PrivatePlacementMember2026-03-240001503802us-gaap:LineOfCreditMember2026-01-012026-03-310001503802srt:ScenarioForecastMemberkpti:NewTwoThousandTwentyNineNotesAndTwoThousandTwentyEightNotesMembersrt:MaximumMember2026-10-100001503802kpti:TwoThousandTwentyFiveNotesMember2018-10-310001503802kpti:TwoThousandTwentyEightNotesMember2025-12-310001503802kpti:MenariniLicenseAgreementMemberus-gaap:RoyaltyMember2026-01-012026-03-310001503802us-gaap:PrivatePlacementMemberkpti:TwoThousandTwentyFivePlacementWarrantsMember2025-10-010001503802kpti:RevenueInterestFinancingAgreementMember2019-09-012019-09-300001503802kpti:TwoThousandTwentyTwoWarrantsMember2026-01-012026-03-310001503802us-gaap:HealthCareOtherMember2026-01-012026-03-310001503802kpti:TwoThousandTwentyFiveConvertibleNotesMember2026-01-012026-03-310001503802us-gaap:ProductMember2025-12-310001503802us-gaap:CommonStockMemberkpti:TwoThousandTwentyNineNotesMember2025-10-072025-10-0700015038022025-10-310001503802kpti:TwoThousandTwentyNineNotesMember2026-01-012026-03-310001503802kpti:NewTwoThousandTwentyNineNotesAndTwoThousandTwentyNineNotesMember2026-01-012026-03-310001503802us-gaap:MoneyMarketFundsMember2025-12-310001503802us-gaap:OperatingSegmentsMember2025-01-012025-03-310001503802us-gaap:AdditionalPaidInCapitalMember2025-01-012025-03-310001503802us-gaap:OperatingSegmentsMemberus-gaap:ProductMember2025-01-012025-03-3100015038022025-03-310001503802us-gaap:FairValueInputsLevel3Memberkpti:LiabilityClassifiedWarrantsMember2026-03-310001503802kpti:ShortTermInvestmentsCorporateDebtSecuritiesMember2025-12-310001503802us-gaap:ResearchAndDevelopmentExpenseMember2026-01-012026-03-310001503802kpti:TwoThousandTwentyFiveWarrantsMember2025-12-310001503802us-gaap:CommonStockMemberkpti:TwoThousandTwentyFiveNotesMember2025-10-012025-10-310001503802us-gaap:AdditionalPaidInCapitalMember2024-12-3100015038022024-12-310001503802us-gaap:CostOfSalesMember2025-01-012025-03-310001503802us-gaap:USGovernmentAgenciesDebtSecuritiesMember2025-12-310001503802us-gaap:AccumulatedOtherComprehensiveIncomeMember2026-01-012026-03-310001503802us-gaap:SellingGeneralAndAdministrativeExpensesMember2026-01-012026-03-310001503802srt:ScenarioForecastMember2027-05-082027-05-080001503802us-gaap:FairValueInputsLevel3Memberkpti:DeferredRoyaltyObligationMember2025-12-310001503802us-gaap:CommonStockMember2026-01-012026-03-310001503802srt:ScenarioForecastMember2026-10-112026-10-1100015038022026-03-012026-03-310001503802kpti:AmendedTermLoanMember2026-03-310001503802kpti:XpovioMember2026-01-012026-03-3100015038022026-05-070001503802us-gaap:RestrictedStockUnitsRSUMember2026-01-012026-03-310001503802kpti:TwoThousandTwentyNineNotesMemberkpti:HealthcareRoyaltyPartnersIvLpMember2024-05-130001503802us-gaap:HealthCareOtherMember2025-01-012025-03-310001503802us-gaap:FairValueInputsLevel2Memberkpti:ShortTermInvestmentsCorporateDebtSecuritiesMember2025-12-310001503802kpti:TwoThousandTwentyTwoWarrantsMember2026-03-310001503802us-gaap:RetainedEarningsMember2025-01-012025-03-310001503802us-gaap:OperatingSegmentsMember2026-01-012026-03-310001503802kpti:AntengeneTherapeuticsLimitedMemberus-gaap:RoyaltyMember2025-01-012025-03-310001503802kpti:TwoThousandTwentyNineConvertableNotesMember2026-01-012026-03-310001503802us-gaap:MoneyMarketFundsMember2026-03-310001503802kpti:RevenueInterestAgreementAndAmendedRevenueInterestAgreementMember2026-03-310001503802us-gaap:WarrantMember2025-01-012025-03-310001503802kpti:RevenueInterestFinancingAgreementMemberkpti:HealthcareRoyaltyPartnersIvLpMember2026-01-012026-03-3100015038022025-01-012025-03-310001503802kpti:LicenseAndOtherMember2026-01-012026-03-310001503802kpti:TwoThousandTwentyFiveWarrantsMemberus-gaap:PrivatePlacementMember2025-10-012025-10-310001503802kpti:SecuritiesPurchaseAgreementMemberkpti:TwoThousandTwentySixWarrantsMemberus-gaap:PrivatePlacementMember2026-03-242026-03-240001503802us-gaap:FairValueInputsLevel3Memberkpti:LiabilityClassifiedWarrantsMember2025-12-310001503802kpti:PreFundedWarrantsMemberkpti:TwoThousandTwentyNineNotesMember2025-10-012025-10-310001503802srt:MaximumMemberkpti:MarchTwoThousandTwentySixWarrantsMember2026-03-3100015038022026-03-310001503802kpti:TwoThousandTwentySixWarrantsMember2026-01-012026-03-310001503802kpti:AmendedRevenueInterestAgreementMember2024-05-310001503802kpti:TwoThousandTwentyFivePlacementWarrantsMember2026-03-310001503802kpti:NewTwoThousandTwentyNineNotesMember2026-03-310001503802us-gaap:AdditionalPaidInCapitalMember2026-01-012026-03-310001503802kpti:PreFundedWarrantsMember2026-03-31xbrli:purexbrli:shareskpti:Segmentiso4217:USDxbrli:shareskpti:Daysiso4217:USD

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-Q

(Mark One)

☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the quarterly period ended March 31, 2026

☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from to

Commission file number: 001-36167

Karyopharm Therapeutics Inc.

(Exact name of registrant as specified in its charter)


Delaware		26-3931704
(State or other jurisdiction of incorporation or organization)		(I.R.S. Employer Identification Number)

85 Wells Avenue, 2nd Floor Newton, MA		02459
(Address of principal executive offices)		(Zip Code)

(617) 658-0600

(Registrant’s telephone number, including area code)

Securities registered pursuant to Section 12(b) of the Act:

     Title of each class

     Trading
Symbol(s)

     Name of each exchange
on which registered

     Common Stock, $0.0001 par value

     KPTI

     Nasdaq Global Select Market

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ☒ No ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes ☒ No ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.


Large accelerated filer	☐	Accelerated filer	☐

Non-accelerated filer	☒	Smaller reporting company	☒

		Emerging growth company	☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes ☐ No ☒

As of May 7, 2026, there were 22,662,943 shares of Common Stock, $0.0001 par value per share, outstanding.

Table of Contents

TABLE OF CONTENTS


	PART I - FINANCIAL INFORMATION	2

Item 1.	Condensed Consolidated Financial Statements (Unaudited)	2
	Condensed Consolidated Balance Sheets	2
	Condensed Consolidated Statements of Operations	3
	Condensed Consolidated Statements of Comprehensive Income (Loss)	4
	Condensed Consolidated Statements of Cash Flows	5
	Condensed Consolidated Statements of Stockholders’ Deficit	6
	Notes to Condensed Consolidated Financial Statements	7
Item 2.	Management’s Discussion and Analysis of Financial Condition and Results of Operations	20
Item 3.	Quantitative and Qualitative Disclosures About Market Risk	29
Item 4.	Controls and Procedures	29

	PART II - OTHER INFORMATION	30

Item 1A.	Risk Factors	30
Item 5.	Other Information	81
Item 6.	Exhibits	82
	Signatures	83

Table of Contents

PART I - FINANCIAL INFORMATION

Item 1. Condensed Consolidated Financial Statements (Unaudited).

KARYOPHARM THERAPEUTICS INC.

CONDENSED CONSOLIDATED BALANCE SHEETS

(unaudited)

(in thousands, except per share amounts)


	March 31, 2026			December 31, 2025
Assets
Current assets:
Cash and cash equivalents	$	90,850		$	60,540
Investments		—			3,204
Accounts receivable, net		23,357			26,178
Inventory		3,599			4,038
Prepaid expenses and other current assets		8,527			9,186
Total current assets		126,333			103,146
Property and equipment, net		91			104
Operating lease right-of-use assets		4,409			4,548
Restricted cash		317			351
Other assets		267			267
Total assets	$	131,417		$	108,416
Liabilities and stockholders’ deficit
Current liabilities:
Accounts payable	$	4,279		$	4,003
Accrued expenses		76,303			64,498
Senior secured term loan		32,232			21,010
Operating lease liabilities		1,018			969
Other current liabilities		3,470			1,580
Total current liabilities		117,302			92,060
Convertible senior notes due 2029		86,252			89,973
Convertible senior notes due 2028		17,659			21,117
Senior secured term loan, net of current portion		88,245			94,795
Deferred royalty obligation		72,338			72,338
Common stock warrants		9,521			14,221
Operating lease liabilities, net of current portion		5,468			5,743
Other liabilities		278			11,095
Total liabilities		397,063			401,342
Stockholders’ deficit:
Preferred stock, $0.0001 par value; 5,000 shares authorized; none issued and outstanding		—			—
Common stock, $0.0001 par value; 106,000 shares authorized; 22,544 and 18,311 shares issued and outstanding as of March 31, 2026 and December 31, 2025, respectively		14			14
Additional paid-in capital		1,516,188			1,466,488
Accumulated other comprehensive income		43			71
Accumulated deficit		(1,781,891	)		(1,759,499	)
Total stockholders’ deficit		(265,646	)		(292,926	)
Total liabilities and stockholders’ deficit	$	131,417		$	108,416

See accompanying notes to condensed consolidated financial statements.

Table of Contents

KARYOPHARM THERAPEUTICS INC.

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS

(unaudited)

(in thousands, except per share amounts)


	For the Three Months Ended March 31,
	2026			2025
Revenues:
Product revenue, net	$	29,163		$	21,054
License and other revenue		5,903			8,961
Total revenue		35,066			30,015
Operating expenses:
Cost of sales		1,345			1,301
Research and development		33,797			34,618
Selling, general and administrative		26,684			27,352
Total operating expenses		61,826			63,271
Loss from operations		(26,760	)		(33,256	)
Other income (expense):
Interest income		511			1,000
Interest expense		(12,553	)		(10,994	)
Other income, net		16,411			19,824
Total other income, net		4,369			9,830
Loss before income taxes		(22,391	)		(23,426	)
Income tax provision		(1	)		(36	)
Net loss	$	(22,392	)	$	(23,462	)
Basic net loss per share	$	(1.02	)	$	(2.77	)
Diluted net loss per share	$	(1.24	)	$	(2.77	)
Weighted-average number of common shares outstanding used to compute basic net loss per share		22,014			8,470
Weighted-average number of common shares outstanding used to compute diluted net loss per share		24,715			8,470

See accompanying notes to condensed consolidated financial statements.

Table of Contents

KARYOPHARM THERAPEUTICS INC.

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS)

(unaudited)

(in thousands)


	For the Three Months Ended March 31,
	2026			2025
Net loss	$	(22,392	)	$	(23,462	)
Other comprehensive (loss) income
Unrealized loss on investments		(3	)		(26	)
Foreign currency translation adjustment		(25	)		61
Comprehensive loss	$	(22,420	)	$	(23,427	)

See accompanying notes to condensed consolidated financial statements.

Table of Contents

KARYOPHARM THERAPEUTICS INC.

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS

(unaudited)

(in thousands)


	For the Three Months Ended March 31,
	2026			2025
Operating activities
Net loss	$	(22,392	)	$	(23,462	)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense		3,007			3,560
Depreciation		12			78
Amortization of debt issuance costs and discounts		2,362			2,573
Interest expense added to debt principal		6,911			—
Net amortization of premiums and discounts on investments		2			(236	)
Change in fair value of embedded derivatives and common stock warrants		(16,481	)		(19,972	)
Changes in operating assets and liabilities:
Accounts receivable, net		2,821			(4,477	)
Inventory		439			(30	)
Prepaid expenses and other assets		659			1,960
Operating lease right-of-use assets		139			407
Accounts payable		276			765
Accrued expenses and other liabilities		(257	)		(412	)
Operating lease liabilities		(226	)		262
Net cash used in operating activities		(22,728	)		(38,984	)
Investing activities
Proceeds from maturities of investments		3,200			15,288
Net cash provided by investing activities		3,200			15,288
Financing activities
Proceeds from issuance of common stock under Open Market Sale Agreement		20,233			—
Proceeds from issuance of common stock and warrants in private placement offering		30,000			—
Payment of equity issuance costs		(431	)		—
Net cash provided by financing activities		49,802			—
Effect of exchange rates on cash, cash equivalents and restricted cash		2			5
Net increase (decrease) in cash, cash equivalents and restricted cash		30,276			(23,691	)
Cash, cash equivalents and restricted cash at beginning of period		60,891			62,814
Cash, cash equivalents and restricted cash at end of period	$	91,167		$	39,123
Reconciliation of cash, cash equivalents and restricted cash reported within the condensed consolidated balance sheets
Cash and cash equivalents	$	90,850		$	38,783
Long-term restricted cash		317			340
Total cash, cash equivalents and restricted cash	$	91,167		$	39,123
Supplemental disclosures:
Cash paid for interest on deferred royalty obligation	$	—		$	2,122
Cash paid for interest on convertible debt and term loan	$	—		$	5,135
Equity issuance costs included in accounts payable and accrued expenses	$	1,508		$	—
Cash paid for amounts included in the measurement of operating lease liabilities	$	467		$	—
Debt issued for interest payments	$	6,911		$	—

See accompanying notes to condensed consolidated financial statements.

Table of Contents

KARYOPHARM THERAPEUTICS INC.

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ DEFICIT

(unaudited)

(in thousands)


	Common Shares				Additional Paid-In Capital		Accumulated Other Comprehensive (Loss) Income			Accumulated Deficit			Total Stockholders’ Deficit
	Shares		Amount
Balance as of December 31, 2025		18,311	$	14	$	1,466,488	$	71		$	(1,759,499	)	$	(292,926	)
Vesting of restricted stock		209		—		—		—			—			—
Issuance of common stock under Open Market Sale Agreement, net of issuance costs		2,994		—		19,827		—			—			19,827
Issuance of common stock and warrants in private placement offering, net of issuance costs		1,030		—		26,866		—			—			26,866
Stock-based compensation		—		—		3,007		—			—			3,007
Unrealized loss on investments		—		—		—		(3	)		—			(3	)
Foreign currency cumulative translation adjustment		—		—		—		(25	)		—			(25	)
Net loss		—		—		—		—			(22,392	)		(22,392	)
Balance as of March 31, 2026		22,544	$	14	$	1,516,188	$	43		$	(1,781,891	)	$	(265,646	)

Balance as of December 31, 2024		8,413	$	13	$	1,377,786	$	(356	)	$	(1,563,460	)	$	(186,017	)
Vesting of restricted stock		155		—		—		—			—			—
Stock-based compensation		—		—		3,560		—			—			3,560
Unrealized loss on investments		—		—		—		(26	)		—			(26	)
Foreign currency cumulative translation adjustment		—		—		—		61			—			61
Net loss		—		—		—		—			(23,462	)		(23,462	)
Balance as of March 31, 2025		8,568	$	13	$	1,381,346	$	(321	)	$	(1,586,922	)	$	(205,884	)

See accompanying notes to condensed consolidated financial statements.

Table of Contents

KARYOPHARM THERAPEUTICS INC.

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

1. Nature of Business, Basis of Presentation and Segment Information

Nature of Business

Karyopharm Therapeutics Inc., a Delaware corporation (collectively with its subsidiaries, the “Company,” “we,” “us,” or “our”), is a commercial-stage pharmaceutical company pioneering novel cancer therapies and dedicated to the discovery, development and commercialization of first-in-class drugs directed against nuclear export for the treatment of cancer. Our scientific expertise is based upon an understanding of the regulation of intracellular communication between the nucleus and the cytoplasm. We have discovered and are developing and commercializing novel, small molecule XPO1 inhibitor compounds that inhibit the nuclear export protein exportin 1. Our primary focus is on marketing XPOVIO® (selinexor) in its currently approved indications, as well as developing and seeking regulatory approval of selinexor as an oral agent targeting multiple high unmet need cancer indications, including our lead clinical programs in myelofibrosis and endometrial cancer and our other late-stage clinical program in multiple myeloma. We were incorporated in Delaware on December 22, 2008 and have a principal place of business in Newton, Massachusetts.

Our lead asset, XPOVIO, received its initial U.S. approval from the U.S. Food and Drug Administration in July 2019 and is currently approved and marketed in the U.S. for the following indications: (i) in combination with bortezomib and dexamethasone for the treatment of adult patients with multiple myeloma who have received at least one prior therapy; and (ii) in combination with dexamethasone for the treatment of adult patients with relapsed or refractory multiple myeloma who have received at least four prior therapies and whose disease is refractory to at least two proteasome inhibitors, at least two immunomodulatory agents, and an anti-CD38 monoclonal antibody. The commercialization of XPOVIO and NEXPOVIO® (selinexor) (the brand name for selinexor in Europe and the United Kingdom) outside of the U.S. is managed by our partners in their respective territories. XPOVIO/NEXPOVIO has received regulatory approvals in various indications in more than 50 territories and countries outside the U.S. and is commercially available in a growing number of countries as our partners continue to secure reimbursement approvals.

Liquidity, Capital Resources and Going Concern

We have historically financed our operations primarily through a combination of proceeds from (i) product revenue sales; (ii) public and private placements of equity securities; (iii) the issuance of convertible debt; (iv) a term loan; (v) our deferred royalty obligation; (vi) at the market offerings; and (vii) business development activities. As of March 31, 2026, we had $90.9 million of cash and cash equivalents and an accumulated deficit of $1.8 billion. We have incurred significant operating losses since our inception and we anticipate that we will continue to incur significant operating losses to maintain our research and development programs, including as we continue to develop and seek regulatory approval of selinexor for multiple cancer indications, and to support our continued operations. As a result, our continued operations are dependent on our ability to raise additional funding or enter into other strategic alternatives and marketing XPOVIO in its currently approved indications. Based on our current business plan and current capital resources, combined with the uncertainty regarding the availability of additional funding or other strategic alternatives and considering our debt service obligations and financial covenant to maintain minimum liquidity, we have concluded that there is substantial doubt regarding our ability to continue as a going concern within one year after the date the accompanying condensed consolidated financial statements are issued. We plan to address the conditions that raise substantial doubt regarding our ability to continue as a going concern by, among other things, obtaining additional funding through equity offerings, debt financings and refinancings, collaborations, strategic alliances and/or licensing arrangements. However, there is no assurance that these efforts will result in additional funding, strategic alliances or licensing arrangements or sufficiently address our ability to continue as a going concern.

If we utilize our capital resources more quickly than anticipated or are unable to obtain additional funding or engage in strategic alternatives, we may have to significantly curtail, delay, reduce or eliminate one or more of our research and development programs or any current or future commercialization efforts for one or more of our products or product candidates, which could materially adversely affect our business, financial condition, and results of operations. We have and may determine to take additional actions to reduce our spending in the near term, including reductions to our workforce. If we are unable to continue as a going concern, we may have to liquidate assets and may receive less than the value at which those assets are carried on our financial statements. We may also determine to cease operations or file for bankruptcy protection. In any of these circumstances, it is likely that investors will lose all or part of their investment. If there remains substantial doubt about our ability to continue as a going concern, investors or other financing sources may be unwilling to provide funding to us on commercially reasonable terms, if at all. The accompanying condensed consolidated financial statements do not include any adjustments to the carrying amounts and classification of assets and liabilities that may be necessary if we were unable to continue as a going concern.

Table of Contents

Basis of Presentation

The accompanying unaudited condensed consolidated financial statements of the Company have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) for interim financial reporting and as required by Regulation S-X, Rule 8-03. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In our opinion, all adjustments (including those which are normal and recurring) considered necessary for a fair presentation of the interim financial information have been included. When preparing financial statements in conformity with GAAP, we must make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues, expenses and related disclosures at the date of the financial statements. Actual results could differ from those estimates. Additionally, operating results for the three months ended March 31, 2026 are not necessarily indicative of the results that may be expected for any other interim period or for the fiscal year ending December 31, 2026. For further information, refer to the financial statements and footnotes included in our Annual Report on Form 10-K for the year ended December 31, 2025 as filed with the Securities and Exchange Commission on February 13, 2026 (“Annual Report”).

Basis of Consolidation

The condensed consolidated financial statements as of March 31, 2026 include the accounts of Karyopharm Therapeutics Inc. and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation.

The significant accounting policies used in preparation of these condensed consolidated financial statements in this Form 10-Q are consistent with those discussed in Note 2, “Summary of Significant Accounting Policies,” in our Annual Report.

Segment Information

Operating segments are defined as components of an enterprise whose operating results are regularly reviewed by the Chief Operating Decision Maker (“CODM”) to allocate resources and assess performance. We view our operations and manage our business as a single operating segment, which is the business of discovering, developing and commercializing drugs to treat cancer. All our revenue and all our long-lived assets are attributable to our single operating segment and to Karyopharm Therapeutics Inc., which is domiciled in the United States.

Our CODM is our Chief Executive Officer who uses net loss as reported on the condensed consolidated statements of operations to monitor budget versus actual results and to ensure we have sufficient capital resources to develop and seek regulatory approval of our product candidates. The following table presents the significant revenue and expense categories (in thousands) in our single operating segment:


	For the Three Months Ended March 31,
	2026			2025
Revenue from external customers	$	35,066		$	30,015
Cost of sales (1)		(1,319	)		(1,255	)
Research and development expenses (2)		(34,016	)		(35,564	)
Commercial expenses (2)		(11,419	)		(12,484	)
General and administrative expenses (2)		(12,065	)		(10,408	)
Other segment income (3)		1,361			6,234
Net loss of our single operating segment	$	(22,392	)	$	(23,462	)

(1) Excludes stock-based compensation expense
(2) Excludes stock-based compensation expense and the effects of certain allocations of certain expenses
(3) Includes total other income, net and income tax provision on the condensed consolidated statements of operations and stock-based compensation expense

Table of Contents

2. Product Revenue

To date, our only source of product revenue has been from the U.S. sales of XPOVIO. Net product revenue, including provisions primarily consisting of distribution fees and cash discounts, as well as reserves for chargebacks, rebates and returns, were as follows (in thousands):


	For the Three Months Ended March 31,
	2026			2025
Gross product revenue	$	37,307		$	38,297
Provisions for product revenue		(8,144	)		(17,243	)
Total product revenue, net	$	29,163		$	21,054

As of March 31, 2026 and December 31, 2025, net product revenue of $19.6 million and $22.7 million, respectively, were included in accounts receivable. To date, we have had no bad debt write-offs and we do not currently have credit issues with any customers. There were no credit losses associated with accounts receivable as of March 31, 2026 and December 31, 2025.

3. Inventory

The following table presents our inventory (in thousands), all of which was related to XPOVIO:


	As of March 31, 2026		As of December 31, 2025
Raw materials	$	628	$	628
Work in process		2,707		2,980
Finished goods		264		430
Total inventory	$	3,599	$	4,038

4. License Agreements

In prior periods, we entered into license agreements with Berlin-Chemie AG, an affiliate of the Menarini Group (“Menarini”), and Antengene Therapeutics Limited (“Antengene”), both of which are accounted for within the scope of Accounting Standards Codification 606, Revenue from Contracts with Customers. For further details on the terms and accounting treatment considerations for these contracts, please refer to Note 5, “License Agreements,” to our consolidated financial statements contained in Item 8 of our Annual Report.

The following table presents information about our license and other revenue (in thousands):


	For the Three Months Ended March 31,
	2026		2025
Menarini	$	1,828	$	8,196
Antengene		499		652
Other		3,576		113
Total license and other revenue	$	5,903	$	8,961

During the three months ended March 31, 2026, we recognized $1.4 million of royalty revenue from Menarini, $0.5 million of royalty revenue from Antengene, and $3.5 million of milestone revenue under a licensing agreement with a privately-held biotech company related to the research, development and commercialization of verdinexor for the treatment of cancer in certain animals.

During the three months ended March 31, 2025, we recognized $7.0 million of revenue for the reimbursement of development-related expenses, $0.9 million of royalty revenue from Menarini, and $0.6 million of royalty revenue from Antengene.

License and other revenue of $3.8 million and $3.5 million were included in accounts receivable as of March 31, 2026 and December 31, 2025, respectively.

Table of Contents

5. Fair Value Measurements

Cash, cash equivalents, and restricted cash are presented at fair value as of March 31, 2026 and December 31, 2025. Other financial instruments, including accounts receivable, net, other current assets, other assets, accounts payable, and accrued expenses, are presented at amounts that approximate fair value as of March 31, 2026 and December 31, 2025 due to their short-term nature.

Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. We disclose information on all assets and liabilities reported at fair value that enables an assessment of the inputs used in determining the reported fair values. The fair value hierarchy prioritizes valuation inputs based on the observable nature of those inputs. The fair value hierarchy applies only to the valuation inputs used in determining the reported fair value and is not a measure of credit quality. The hierarchy defines three levels of valuation inputs:

Level 1 - Quoted prices in active markets for identical assets or liabilities

Level 2 - Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly

Level 3 - Unobservable inputs that reflect the assumptions market participants would use in pricing the asset or liability

Items classified as Level 2 consist of corporate debt securities, commercial paper and U.S. government and agency securities. We estimate the fair value of these marketable securities by taking into consideration valuations obtained from third-party pricing sources. These pricing sources utilize industry standard valuation models, including both income and market-based approaches, for which all significant inputs are observable, either directly or indirectly, to estimate fair value. These inputs include market pricing based on real-time trade data for the same or similar securities, issuer credit spreads, benchmark yields, and other observable inputs. We validate the prices provided by our third-party pricing sources by understanding the models used, obtaining market values from other pricing sources and analyzing pricing data in certain instances.

The following tables present information about our financial assets that have been measured at fair value and indicate the fair value hierarchy of the valuation inputs utilized to determine such fair value (in thousands):


	As of March 31, 2026		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash equivalents:
Money market funds	$	65,746	$	65,746	$	—	$	—
U.S. government and agency securities		7,409		—		7,409		—
	$	73,155	$	65,746	$	7,409	$	—


	As of December 31, 2025		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash equivalents:
Money market funds	$	37,224	$	37,224	$	—	$	—
U.S. government and agency securities		7,306		—		7,306		—
Investments:
Corporate debt securities		3,204		—		3,204		—
	$	47,734	$	37,224	$	10,510	$	—

Table of Contents

In certain cases where there is limited activity or less transparency around inputs to valuation, the related assets or liabilities are classified as Level 3. The following liabilities are measured at fair value at the end of each reporting period, with changes in fair value recognized as a component of other income, net on our condensed consolidated statements of operations. See Note 10, “Long-Term Obligations” to our condensed consolidated financial statements for further discussion of these liabilities:

(1)

The embedded derivative liabilities (the “Convertible Notes Derivatives”) associated with the 9.00% senior secured convertible notes due 2029 (the “New 2029 Notes”) and 9.00% senior secured convertible notes due 2028 (the “2028 Notes”) are included as components of these debt instruments on our condensed consolidated balance sheets. The valuation method for the Convertible Notes Derivatives incorporates certain unobservable Level 3 key inputs including: (i) the volatility of our common stock price and (ii) our estimated credit spread.

(2)

The warrants to purchase up to 3,068,417 shares of our common stock issued in May 2024 (the “2024 Warrants”) are classified as a long-term liability on our condensed consolidated balance sheets. The warrants to purchase up to 4,421,518 shares of our common stock issued in March 2026 (the “2026 Warrants”) are classified as a current liability on our condensed consolidated balance sheets. The 2024 Warrants and 2026 Warrants are collectively referred to as the “Liability Classified Warrants”. The valuation method for the Liability Classified Warrants incorporates certain unobservable Level 3 key inputs including: (i) the volatility of our common stock price and (ii) an estimate of when the 2024 Warrants will be exercised based on an option pricing model.

The following table sets forth a summary of the changes in the estimated fair value of these liabilities, which are all classified as Level 3 (in thousands):


	Convertible Notes Derivatives			Liability Classified Warrants
Balance as of December 31, 2025	$	27,455		$	14,221
Initial recognition		—			1,601
Change in fair value		(11,781	)		(4,700	)
Balance as of March 31, 2026	$	15,674		$	11,122

6. Investments

We did not have any investments in debt securities as of March 31, 2026. The following table summarizes our investments in debt securities, classified as available-for-sale (in thousands) as of December 31, 2025:


	As of December 31, 2025
	Amortized Cost		Total Unrealized Gains		Total Unrealized Losses		Aggregate Fair Value
Corporate debt securities	$	3,202	$	2	$	—	$	3,204

We determine the appropriate classification of our investments at the time of purchase. All of our investments are reported as short-term as they are available for use during the normal cycle of business. We review any investment when its fair value is less than its amortized cost and when evidence indicates that the investment’s carrying amount is not recoverable within a reasonable period. We evaluate whether the decline in fair value has resulted from credit losses or other factors. In making this assessment, we consider the extent to which fair value is less than amortized cost, any changes to the rating of the security by a rating agency, and adverse conditions specifically related to the security, among other factors. If this assessment indicates that a credit loss exists, the present value of cash flows expected to be collected from the investment is compared to its amortized cost basis. If the present value of cash flows expected to be collected is less than the amortized cost basis, a credit loss exists and an allowance for credit losses is recorded on our condensed consolidated balance sheet, limited by the amount that the fair value is less than the amortized cost basis. Any impairment that is not related to a credit loss is recognized in other comprehensive (loss) income.

Changes in the allowance for credit losses are recorded as a provision for (or reversal of) credit loss expense. Losses are charged against the allowance when we believe the uncollectability of an investment is confirmed or when either of the criteria regarding intent or requirement to sell is met. We do not intend to sell the investments before recovery of their amortized cost bases, which may be at maturity.

Table of Contents

7. Net Loss Per Share

Basic net loss per common share is calculated using the two-class method by dividing the net loss allocated to common shares by the weighted-average number of common shares outstanding for the period, which includes the common shares deliverable upon the exercise of outstanding pre-funded warrants. Diluted net loss per common share is calculated by adjusting net loss to remove the effects from potential dilutive common shares and dividing this adjusted amount by the weighted average number of common shares and potential dilutive common shares outstanding for the period. Potential dilutive common shares are not included if their effect is anti-dilutive.

As discussed further in Note 10, “Long-Term Obligations”, the conversion obligation for our 3.00% unsecured convertible senior notes due 2025 (the “2025 Notes”) and 6.00% senior secured convertible notes due 2029 (the “2029 Notes”) when outstanding, were potentially settleable in common shares. No 2025 Notes or 2029 Notes were outstanding during the three months ended March 31, 2026. The 2025 Notes and 2029 Notes did not impact the calculation of dilutive loss per common share during the three months ended March 31, 2025 because they were anti-dilutive in that period.

As discussed further in Note 10, “Long-Term Obligations”, the conversion obligation for our New 2029 Notes and 2028 Notes can potentially be settled in common shares. The New 2029 Notes did not impact the calculation of dilutive loss per common share during the three months ended March 31, 2026 because they were anti-dilutive in that period. See the table below for the impact of the 2028 Notes on dilutive loss per common share during the three months ended March 31, 2026. No 2028 Notes or New 2029 Notes were outstanding during the three months ended March 31, 2025.

As discussed further in Note 11, “Common Share Warrants”, warrants to purchase common shares were outstanding as of March 31, 2026 and 2025. All outstanding warrants, except pre-funded warrants, are not included in the calculation of basic net loss per share because the warrant holders do not have an obligation to share in our losses. The 2024 Warrants did not impact the calculation of dilutive loss per common share during the three months ended March 31, 2025 because they were anti-dilutive in that period. See the table below for the impact of the 2024 Warrants on dilutive loss per common share during the three months ended March 31, 2026. All other warrants, except pre-funded warrants, did not impact the calculation of dilutive loss per common share during the three months ended March 31, 2026 and 2025 because they either did not exist or were anti-dilutive during these periods. Pre-funded warrants are included in the calculation of basic and diluted net loss per share due to their de-minimis exercise price.

The following is a reconciliation of the numerator and denominator used to calculate diluted net loss per common share (in thousands except per share amounts):


	For the Three Months Ended March 31, 2026
Net loss	$	(22,392	)
Add back change in fair value of 2024 Warrants		(4,700	)
Add back change in fair value of embedded derivatives on 2028 Notes		(4,083	)
Add back interest expense on 2028 Notes		624
Numerator for diluted net loss per common share (A)	$	(30,551	)
Weighted-average number of common shares outstanding		22,014
Dilutive effect of 2024 Warrants using treasury stock method		396
Dilutive effect of 2028 Notes calculated using the if-converted method		2,305
Denominator for diluted net loss per common share (B)		24,715
Diluted net loss per common share (= A / B)	$	(1.24	)

The following potentially dilutive securities were excluded from the calculation of diluted net loss per share due to their anti-dilutive effect (in thousands):


	As of March 31,
	2026		2025
Common shares deliverable upon conversion of 2025 Notes		—		103
Common shares deliverable upon conversion of 2029 Notes		—		3,436
Common shares deliverable upon conversion of New 2029 Notes		4,799		—
Outstanding common stock warrants, except pre-funded warrants		10,976		3,704
Outstanding stock options		477		506
Unvested restricted stock units		1,302		869

Table of Contents

8. Stock-based Compensation Expense

The following table summarizes stock-based compensation expense included in operating expenses (in thousands):


	For the Three Months Ended March 31,
	2026		2025
Cost of sales	$	26	$	46
Research and development		886		915
Selling, general and administrative		2,095		2,599
Total	$	3,007	$	3,560

9. Stockholders’ Equity

In February 2023, we entered into an Open Market Sale Agreement (the “Open Market Sale Agreement”) with Jefferies LLC, as agent (“Jefferies”). Under the Open Market Sale Agreement, we may issue and sell shares of our common stock having an aggregate offering price of up to $100.0 million (the “Shares”) from time to time through Jefferies (the “Open Market Offering”).

Under the Open Market Sale Agreement, Jefferies may sell the Shares by methods deemed to be an “at the market offering” as defined in Rule 415(a)(4) promulgated under the Securities Act of 1933, as amended. We may sell the Shares in amounts and at times to be determined by us from time to time subject to the terms and conditions of the Open Market Sale Agreement, but we have no obligation to sell any of the Shares in the Open Market Offering.

We or Jefferies may suspend or terminate the offering of Shares upon notice to the other party and subject to other conditions. We have agreed to pay Jefferies commissions for its services in acting as agent in the sale of the Shares in the amount of up to 3.00% of gross proceeds from the sale of the Shares pursuant to the Open Market Sale Agreement. We have also agreed to provide Jefferies with customary indemnification and contribution rights.

We sold an aggregate of 2,994,441 Shares under the Open Market Sale Agreement during the three months ended March 31, 2026, resulting in net proceeds of $19.8 million. We did not sell any Shares under the Open Market Sale Agreement during the three months ended March 31, 2025. As of March 31, 2026, $79.8 million of Shares were available for issuance and sale under the Open Market Sale Agreement.

On February 18, 2026, our stockholders approved an amendment to our Restated Certificate of Incorporation, as amended, to increase the number of authorized shares of our capital stock from 58,333,333 shares to 111,000,000 shares and the number of authorized shares of our common stock from 53,333,333 to 106,000,000 shares.

On March 24, 2026, we entered into a Securities Purchase Agreement with RA Capital Healthcare Fund, L.P. pursuant to which we issued and sold in a private placement: (i) 1,030,354 shares of common stock, (ii) pre-funded warrants to purchase up to 3,391,164 shares of common stock, and (iii) accompanying 2026 Warrants to purchase 4,421,518 shares of common stock with an exercise price of $10.00 per share for aggregate net proceeds of $26.9 million. The 2026 Warrants are exercisable until 30 days following our public announcement of topline data results from our Phase 3 XPORT-EC-042 clinical trial of selinexor in patients with endometrial cancer and the pre-funded warrants do not expire. As of March 31, 2026, none of these warrants have been exercised.

10. Long-Term Obligations

2025 Notes

In October 2018, we issued $172.5 million aggregate principal amount of the 2025 Notes in a private offering which matured on October 15, 2025. In May 2024, we exchanged $148.0 million aggregate principal amount of the 2025 Notes for: (i) $111.0 million aggregate principal amount of the 2029 Notes and (ii) 2024 Warrants to purchase up to 3,051,750 shares of our common stock. In October 2025, we exchanged $24.3 million aggregate principal amount of 2025 Notes for: (i) 2,435,146 shares of common stock, (ii) pre-funded warrants to purchase an aggregate of 1,404,087 shares of common stock, and (iii) common stock warrants to purchase an aggregate of 2,502,151 shares of common stock with an exercise price of $6.64 per share and an expiration date of October 10, 2030. We repaid $0.3 million principal amount of 2025 Notes at maturity on October 15, 2025, after which no 2025 Notes were outstanding.

Senior Secured Term Loan

In May 2024, we entered into a credit and guaranty agreement (the “Credit Agreement”) with certain holders of the 2025 Notes and certain entities managed by HealthCare Royalty Management, LLC (“HCRx”), which was subsequently assigned by HCRx to an

Table of Contents

affiliate of KKR & Co. Inc. (“KKR”) in connection with its acquisition of a majority ownership stake in HCRx in July 2025. The Credit Agreement provides for a senior secured term loan facility of $100.0 million which bore interest at a variable rate equal to the applicable secured overnight financing rate plus 9.25%, subject to a floor of 3.00% through June 30, 2025.

In October 2025, we entered into the First Amendment and Waiver to Credit and Guaranty Agreement, under which we borrowed an additional $12.5 million. In February 2026, we entered into a Second Amendment to Credit and Guaranty Agreement (as amended, the “Amended Credit Agreement”) which became effective in March 2026. The senior secured term loan facility under the Amended Credit Agreement (the “Amended Term Loan”) matures in May 2028 and bears interest at a variable rate equal to the applicable secured overnight financing rate plus 10.25% for all interest incurred after June 30, 2025, subject to a floor of 3.00%.

Interest incurred on borrowings under the Amended Term Loan from July 1, 2025 to June 30, 2026 is payable in-kind. Interest incurred on borrowings under the Amended Term Loan after June 30, 2026 is payable in cash quarterly in arrears on March 31, June 30, September 30, and December 31 of each year.

We are required to make quarterly principal payments under the Amended Term Loan on March 10, June 10, September 10, and December 10 of each year. The first principal payment is due on September 10, 2026 and will equal 12.50% of the aggregate principal amount of the Amended Term Loan. All subsequent principal payments will equal 6.25% of the aggregate principal amount of the Amended Term Loan, not including the effect of previous principal payments. The remaining principal is due when the Amended Term Loan matures on May 8, 2028. We are permitted to prepay the Amended Term Loan at any time, subject to a prepayment premium equal to 5% of the principal prepaid through May 8, 2027 (and 0% thereafter). Any principal that is prepaid, repaid pursuant to a mandatory prepayment, or accelerated must be accompanied by a fee equal to 3.00% of the principal amount so prepaid, repaid, or accelerated. In addition, we are required to repay the Amended Term Loan with proceeds from certain asset sales and condemnation events, subject, in some cases, to reinvestment rights.

All obligations under the Amended Credit Agreement are secured on a first priority basis, subject to certain exceptions, by substantially all of our assets. The Amended Credit Agreement contains customary covenants, including a requirement to maintain a certain amount of cash, cash equivalents and investments at all times (the “Minimum Liquidity Covenant Amount”). The Minimum Liquidity Covenant Amount is the lesser of (i) $10.0 million plus 50% of the net cash proceeds received from certain debt and equity issuances and (ii) $25.0 million, and after October 10, 2026, it will be $25.0 million. As of March 31, 2026, we were in compliance with the Minimum Liquidity Covenant Amount and all other covenants under the Amended Credit Agreement.

The Amended Credit Agreement contains restrictions on indebtedness, liens, investments, fundamental changes, asset sales, licensing transactions, dividends, modifications to material agreements, payment of subordinated indebtedness, and other matters customarily restricted in such agreements. Specifically, we are prohibited from exclusively licensing, selling or otherwise disposing of U.S. rights to oncology indications of selinexor. As of March 31, 2026, we were in compliance with these covenants. If certain events of default occur, the Amended Term Loan may be due and payable immediately. These events include the withdrawal of approval of certain indications of selinexor, payment defaults, covenant defaults, bankruptcy, cross-defaults to certain other agreements, change in control and lien priority. Additionally, we have an obligation under the Amended Credit Agreement to appoint a candidate selected by the lenders under the Amended Term Loan to serve as a non-voting observer to our board of directors.

The outstanding balance of the Amended Term Loan consisted of the following (in thousands):


	As of March 31, 2026			As of December 31, 2025
Principal	$	124,588		$	120,398
Less: unamortized debt issuance costs		(4,111	)		(4,593	)
Total	$	120,477		$	115,805

We determined the expected life of the Amended Term Loan was equal to its term. The principal value of the Amended Term Loan approximates its fair value due to the variable interest rate. Total debt issuance costs related to the Amended Term Loan of $5.2 million are being amortized to interest expense through May 2028 using an effective interest rate of 16%.

Table of Contents

The following table sets forth total interest expense recognized related to the Term Loan and Amended Term Loan (in thousands):


	For the Three Months Ended March 31,
	2026		2025
Contractual interest expense	$	4,190	$	3,395
Amortization of debt issuance costs		482		594
Total interest expense	$	4,672	$	3,989

Future minimum payments on the Amended Term Loan as of March 31, 2026 were as follows (in thousands):


Years ended December 31,	Future Minimum Payments
2026	$	32,587
2027		45,132
2028		75,741
Total future minimum payments		153,460
Less: interest expense and unamortized debt issuance costs		(32,983	)
Amended Term Loan	$	120,477

2029 Notes, New 2029 Notes, and 2028 Notes

In May 2024, pursuant to privately negotiated agreements with certain holders of the 2025 Notes, we exchanged $148.0 million aggregate principal amount of the 2025 Notes for: (i) $111.0 million aggregate principal amount of 2029 Notes maturing on May 13, 2029 and (ii) 2024 Warrants to purchase up to 3,051,750 shares of our common stock. We also issued $5.0 million aggregate principal amount of 2029 Notes to HCRx in exchange for a $5.0 million reduction in our deferred royalty obligation. The 2029 Notes bore interest at a rate of 6.00% per year and were convertible into shares of our common stock at an initial conversion rate of 29.6296 shares per $1,000 principal amount, which is equivalent to a conversion price of $33.75 per share of common stock.

In October 2025, we entered into privately negotiated agreements with the holders of the 2029 Notes to exchange $101.0 million aggregate principal amount of the 2029 Notes for $103.5 million aggregate principal amount of newly issued New 2029 Notes maturing on May 13, 2029. We also exchanged $15.0 million aggregate principal amount of the 2029 Notes for: (i) 2,024,344 shares of common stock and (ii) pre-funded warrants to purchase an aggregate of 552,164 shares of common stock. After which no 2029 Notes were outstanding.

The New 2029 Notes are second-lien secured obligations of the Company and are convertible by the holders into shares of our common stock at an initial conversion rate of 44.4444 shares per $1,000 principal amount (the “New 2029 Notes Conversion Option”) which is equivalent to an initial conversion price of $22.50 per share and subject to customary anti-dilution adjustments. Holders of the New 2029 Notes may convert their New 2029 Notes at any time prior to the close of business on May 11, 2029. Upon conversion of the New 2029 Notes, we will deliver shares of our common stock plus cash in lieu of any fractional shares to the holders.

In October 2025, we issued $15.0 million aggregate principal amount of the 2028 Notes for cash proceeds of $15.0 million. The 2028 Notes are senior secured second-lien obligations and are convertible by the holders into shares of our common stock at an initial conversion rate of 150.6024 shares per $1,000 principal amount of 2028 Notes (the “2028 Notes Conversion Option”) which is equivalent to an initial conversion price of $6.64 per share of common stock and subject to customary anti-dilution adjustments. Holders of the 2028 Notes may convert at any time prior to the close of business on October 13, 2028. Upon conversion of the 2028 Notes, we will deliver shares of our common stock plus cash in lieu of any fractional shares to the holders.

Both the New 2029 Notes and 2028 Notes bear interest at a rate of 9.00% per year. Interest on the New 2029 Notes and 2028 Notes incurred from October 10, 2025 to March 31, 2026 will be payable in-kind. Interest incurred after March 31, 2026 will be payable in cash quarterly in arrears on March 31, June 30, September 30, and December 31 of each year.

On or after May 13, 2026 with respect to the New 2029 Notes or October 15, 2026 with respect to the 2028 Notes, we may redeem all or a portion of the New 2029 Notes or all of the 2028 Notes if the last reported sale price of our common stock equals or exceeds 130% with respect to the New 2029 Notes or 165% with respect to the 2028 Notes of the applicable conversion price then in effect for at least 20 trading days during any 30 consecutive trading day period (the “New 2029 Notes and 2028 Notes Redemption

Table of Contents

Options”). Upon redemption, we will: (1) make a cash payment equal to the principal amount of the notes to be redeemed and any accrued and unpaid interest, if any, up to but excluding the redemption date; and (2) deliver a number of shares of common stock equal to the aggregate value of all remaining interest payments on the amount to be redeemed from the redemption date through maturity divided by the market price per share of our common shares on the redemption date. The number of shares of common stock deliverable is subject to a cap of 85.1374 shares per $1,000 principal amount for the New 2029 Notes or 173.3102 shares per $1,000 principal amount for the 2028 Notes. In some cases, we will be required to make an offer to repurchase the New 2029 Notes or 2028 Notes at a 101% premium with proceeds from certain asset sales, subject, in some cases, to reinvestment rights.

If certain corporate events occur prior to the maturity date of the New 2029 Notes or the 2028 Notes, a holder that elects to convert their New 2029 Notes or 2028 Notes, as applicable, may be entitled to receive additional shares of common stock based on a fundamental change make-whole adjustment in the conversion rate in connection with such corporate event. However, in no event can the conversion rate exceed 85.1374 shares per $1,000 principal amount for the New 2029 Notes or 173.3102 shares per $1,000 principal amount for the 2028 Notes. In addition, if we undergo certain fundamental changes, holders may require us to repurchase for cash all or any portion of their New 2029 Notes or 2028 Notes at a price equal to the principal amount to be repurchased, plus any accrued and unpaid interest, up to but excluding the fundamental change repurchase date.

No holder will be entitled to receive shares of our common stock in connection with the New 2029 Notes or 2028 Notes if such receipt would cause the holder (together with its affiliates) to own more than 4.99% (subject to increase or decrease at the election of the holder, but in no event to exceed 19.99%) of the number of shares of the common stock outstanding immediately after giving effect to such event. In addition, a holder may elect to receive pre-funded warrants with respect to any shares of common stock that would otherwise be issuable in connection with the New 2029 Notes or 2028 Notes but for the foregoing ownership limitations. These pre-funded warrants will have an exercise price of $0.0001 per share and will not expire. As of March 31, 2026, no New 2029 Notes or 2028 Notes have been converted into shares of common stock or pre-funded warrants.

In February 2026, we entered into a Forbearance Agreement (the “Forbearance Agreement”) with: (i) all the lenders under the Amended Credit Agreement, (ii) all the holders of the New 2029 Notes and 2028 Notes, and (iii) the investor representative for the investors under our Revenue Interest Agreement, as defined below (collectively, the “Consenting Parties”). The Forbearance Agreement became effective in March 2026 and prevents the exercise of certain rights and remedies with respect to specified matters, including: (i) payment-related defaults through September 30, 2026 that would result from our non-payment of the interest due on June 30, 2026 for the New 2029 Notes and 2028 Notes and (ii) any defaults that result from a requirement under the indentures of the New 2029 Notes and 2028 Notes for us to have a Minimum Liquidity Covenant Amount greater than the lesser of (i) $10.0 million plus 50% of the net cash proceeds received from certain debt and equity issuances and (ii) $25.0 million through October 10, 2026, which effectively aligns the Minimum Liquidity Covenant Amount required under the New 2029 Notes and 2028 Notes with the Minimum Liquidity Covenant Amount required under the Amended Term Loan. The Forbearance Agreement does not constitute a waiver of any defaults or events of default, and the Consenting Parties reserve their rights and remedies, subject to the terms of the Forbearance Agreement.

All obligations under the New 2029 Notes and 2028 Notes are secured on a second priority basis by the same collateral that secures the obligations under the Amended Term Loan. The 2028 Notes rank pari passu with the New 2029 Notes, senior to indebtedness under the Amended Revenue Interest Agreement (as defined below) and behind indebtedness under the Amended Credit Agreement with respect to distributions of proceeds of the enforcement of certain collateral. The New 2029 Notes and 2028 Notes contain covenants and events of default that are generally consistent with the Amended Term Loan. As of March 31, 2026, we were in compliance with these covenants.

We have determined that the New 2029 Notes Conversion Option, the 2028 Notes Conversion Option, and the New 2029 Notes and 2028 Notes Redemption Options are embedded derivatives that require bifurcation from the debt instrument and fair value recognition. These derivatives are referred to as the Convertible Notes Derivatives in Note 5, “Fair Value Measurements” to our condensed consolidated financial statements.

The outstanding balance of the New 2029 Notes consisted of the following (in thousands):


	As of March 31, 2026			As of December 31, 2025
Principal	$	107,974		$	105,598
Less: unamortized debt issuance costs and discounts		(30,337	)		(31,938	)
Plus: fair value of embedded derivatives		8,615			16,313
Total	$	86,252		$	89,973

Table of Contents

The outstanding balance of the 2028 Notes consisted of the following (in thousands):


	As of March 31, 2026			As of December 31, 2025
Principal	$	15,648		$	15,304
Less: unamortized debt issuance costs and discounts		(5,048	)		(5,329	)
Plus: fair value of embedded derivatives		7,059			11,142
Total	$	17,659		$	21,117

We determined the expected life of the New 2029 Notes and 2028 Notes is equal to their contractual terms. As of March 31, 2026, the “if-converted value” did not exceed the remaining principal amount for both the New 2029 Notes and 2028 Notes. The fair value of the New 2029 Notes and 2028 Notes are influenced by market interest rates, our stock price and stock price volatility, and have been classified as Level 3 within the fair value hierarchy as they use unobservable inputs. The estimated fair value of the New 2029 Notes and 2028 Notes as of March 31, 2026 was approximately $86.1 million and $18.9 million, respectively. The estimated fair value of the New 2029 Notes and 2028 Notes as of December 31, 2025 was approximately $92.7 million and $22.8 million, respectively.

Debt issuance costs and discounts related to the New 2029 Notes of $33.3 million are being amortized to interest expense over the term of the New 2029 Notes at an effective interest rate of 22%. The following table sets forth total interest expense recognized related to the 2029 Notes and New 2029 Notes (in thousands):


	For the Three Months Ended March 31,
	2026		2025
Contractual interest expense	$	2,376	$	1,740
Amortization of debt issuance costs and discounts		1,600		1,946
Total interest expense	$	3,976	$	3,686

Debt issuance costs and discounts related to the 2028 Notes of $5.6 million are being amortized to interest expense over the term of the 2028 Notes at an effective interest rate of 25%. We recognized interest expense of $0.6 million related to the 2028 Notes for the three months ended March 31, 2026, which included $0.3 million of contractual interest expense and $0.3 million of amortization.

Future minimum payments on the New 2029 Notes and 2028 Notes as of March 31, 2026 were as follows (in thousands):


Years ended December 31,	New 2029 Notes			2028 Notes
2026	$	7,343		$	1,064
2027		9,718			1,408
2028		9,718			16,763
2029		111,491			—
Total future minimum payments		138,270			19,235
Less: interest expense and unamortized debt issuance costs and discounts		(60,633	)		(8,635	)
Plus: fair value of embedded derivatives		8,615			7,059
Total	$	86,252		$	17,659

Deferred Royalty Obligation

In September 2019, we entered into a Revenue Interest Financing Agreement (the “Revenue Interest Agreement”) with HCRx which was subsequently amended in June 2021, August 2023, May 2024, August 2025, and October 2025, and which was subsequently assigned by HCRx to KKR in connection with its acquisition of a majority ownership stake in HCRx in July 2025 (as amended, the “Amended Revenue Interest Agreement”) under which we have received a total of $135.0 million, less certain transaction expenses. In exchange for this amount, KKR (as successor in interest to HCRx) receives payments from us at a percentage (the “Royalty Rate”) of net revenues of selinexor and any of our other future products, including worldwide net product sales and upfront payments, milestones, and royalties. Total aggregate payments to HCRx and KKR under the Amended Revenue Interest Agreement are capped at $263.3 million (the “Payment Cap”).

In May 2024, we entered into an amendment (the “HCRx Amendment”) to the Amended Revenue Interest Agreement with HCRx, pursuant to which we:

(1)

made a cash payment to HCRx in the amount of $49.5 million;

Table of Contents

(2)

delivered to HCRx a Term Loan note with a principal amount of $15.0 million; and

(3)

delivered to HCRx 2029 Notes with a principal amount of $5.0 million.

As the repayment of the funded amount is contingent upon worldwide net product sales and upfront payments, milestones, and royalties, the repayment term may be shortened or extended depending on actual worldwide net product sales and upfront payments, milestones, and royalties. The repayment period expires on the earlier of (i) the date on which HCRx and KKR have received cash payments in the aggregate totaling $263.3 million or (ii) the legal maturity date of September 26, 2035. If HCRx and KKR have not received total payments in the aggregate equal to $263.3 million by September 26, 2035, we will be required to pay an amount equal to $135.0 million plus a specific annual rate of return less aggregate payments previously paid to HCRx and KKR.

In the event of a change of control, an event of default, including, among others, our failure to pay any amounts due to KKR, insolvency, our failure to pay indebtedness when due, the revocation of regulatory approval of XPOVIO in the U.S. or our breach of any covenant contained in the Amended Revenue Interest Agreement and our failure to cure the breach within the prescribed time frame, we are obligated to pay KKR an amount equal to $263.3 million less aggregate payments previously paid to HCRx and KKR.

After giving effect to the above, as of May 2024, we had made aggregate payments under the Amended Revenue Interest Agreement totaling $135.0 million and the maximum remaining amount we owed to KKR, as successor in interest to HCRx, was $128.3 million. After May 2024, we are obligated to make quarterly payments in the amount of a fixed percentage of our net product revenues, upfront payments, milestones, and royalties earned in the applicable quarter, except that in connection with the October 2025 amendment, KKR waived our obligation to pay royalties on revenue recognized between April 1, 2025 and March 31, 2026.

The HCRx Amendment also subordinates the indebtedness and liens under the Amended Revenue Interest Agreement to the indebtedness and liens under the Amended Term Loan, and, subject to certain exceptions, makes the indebtedness and liens under the Amended Revenue Interest Agreement pari passu with the indebtedness and liens under the New 2029 Notes.

We have evaluated the terms of the Amended Revenue Interest Agreement and concluded that its features are similar to those of a debt instrument. Accordingly, we have accounted for the transaction as long-term debt and presented it as a deferred royalty obligation on our condensed consolidated balance sheets.

As of March 31, 2026, we have made $147.1 million in payments to HCRx. The effective interest rate as of March 31, 2026 was approximately 16%. We have incurred debt issuance costs totaling $2.8 million which have been netted against the debt and are being amortized over the estimated term of the debt using the effective interest method, adjusted on a prospective basis for changes in the underlying assumptions and inputs.

The carrying value of the deferred royalty obligation as of both March 31, 2026 and December 31, 2025 was $72.3 million, which includes the carrying amount of the debt and unamortized debt issuance costs. The carrying value of the deferred royalty obligation approximated fair value as of March 31, 2026 and December 31, 2025 because the obligation is measured using our current estimates of future payments over the life of the arrangement, which are considered Level 3 inputs.

11. Common Share Warrants

In December 2022, we issued to certain institutional investors, in a private placement offering of securities, warrants to purchase up to 635,703 shares of common stock at an exercise price of $95.37 per share (the “2022 Warrants”). The 2022 Warrants are exercisable through December 7, 2027.

In connection with the exchange of the 2025 Notes for the 2029 Notes in May 2024 described in further detail in Note 10, “Long-Term Obligations”, we issued 2024 Warrants to purchase 3,068,417 shares of our common stock at an exercise price of $16.50 per share. In October 2025, we reduced the exercise price from $16.50 per share to $6.64 per share, subject to customary antidilution adjustments. The 2024 Warrants are exercisable through May 13, 2029. If the closing price of our common stock exceeds two times the then current exercise price of the warrants, which is currently equal to $33.00, for 20 trading days during any 30 consecutive trading day period, we can require the holder to exercise the 2024 Warrants. The 2024 Warrants were classified as a long-term liability in our condensed consolidated balance sheets because they did not meet the criteria for equity classification and are measured at fair value at the end of each reporting period as further described in Note 5, “Fair Value Measurements”.

In October 2025, we issued warrants (the “2025 Placement Warrants”) to purchase 1,317,771 shares of common stock. The 2025 Placement Warrants have an exercise price of $6.64 per share, subject to customary anti-dilution adjustments, and are exercisable until the date that is the first to occur of (i) thirty (30) days following the public announcement by the Company of

Table of Contents

the topline data results from the Phase 3 XPORT-EC-042 clinical trial of selinexor in patients with endometrial cancer or (ii) October 10, 2028.

In October 2025, we issued warrants (the “2025 Warrants”) to purchase 4,600,587 shares of common stock at an exercise price of $6.64 per share, subject to customary antidilution adjustments, of which: (i) 2,502,151 were issued to holders of the 2025 Notes as partial consideration for the exchange of the 2025 Notes, (ii) 1,882,530 were issued to certain holders of our long-term obligations described in Note 10, “Long-Term Obligations” to pay various fees incurred in connection with the debt modifications that occurred in October 2025, and (iii) 215,906 were issued to a financial advisor in connection with the debt modifications that occurred in October 2025. The 2025 Warrants are exercisable through October 10, 2030.

In October 2025, we issued warrants (“Pre-Funded Warrants”) to purchase 2,913,136 shares of common stock at an exercise price of $0.0001 per share to certain holders of our long-term obligations described in Note 10, “Long-Term Obligations”, of which: (i) 1,404,087 Pre-Funded Warrants were issued in lieu of common stock and as partial consideration for the exchange of the 2025 Notes, (ii) 552,164 Pre-Funded Warrants were issued in lieu of common stock and as partial consideration for the exchange of the 2029 Notes, and (iii) 956,885 Pre-Funded Warrants were issued in lieu of common stock to pay various fees incurred in connection with the debt modifications that occurred in October 2025. The Pre-Funded Warrants do not expire.

In March 2026, we issued the 2026 Warrants to purchase 4,421,518 shares of common stock with an exercise price of $10.00 per share which are exercisable until thirty (30) days following the public announcement by the Company of the topline data results from the Phase 3 XPORT-EC-042 clinical trial of selinexor in patients with endometrial cancer. In March 2026, we also issued Pre-Funded Warrants to purchase up to 3,391,164 shares of common stock at an exercise price of $0.0001 per share which do not expire.

The 2025 Placement Warrants, 2025 Warrants, and Pre-Funded Warrants met the criteria for equity classification and were recorded to additional paid-in capital within stockholders’ deficit. The 2026 Warrants were classified as a current liability in our condensed consolidated balance sheets because they did not meet the criteria for equity classification and are measured at fair value at the end of each reporting period as further described in Note 5, “Fair Value Measurements”.

The 2024 Warrants, 2025 Placement Warrants, 2025 Warrants, 2026 Warrants, and Pre-Funded Warrants cannot be exercised if such an exercise results in the holder (together with its affiliates) to own more than 4.99% (for the 2024 Warrants, 2025 Placement Warrants, 2025 Warrants, and Pre-Funded Warrants issued in 2025) or 9.99% (for the 2026 Warrants and Pre-Funded Warrants issued in 2026) of our common stock outstanding on the date of receipt. These percentages are subject to increase or decrease at the election of the holder, but cannot exceed 19.99% of our common stock outstanding on the date of receipt.

The holders of the 2024 Warrants, 2025 Warrants, and 2026 Warrants may elect to receive pre-funded warrants with respect to any common stock that would otherwise be issuable but for the foregoing ownership limitations. These pre-funded warrants will have an exercise price of $0.0001 per share and will not expire.

The following is a summary of activity related to our common stock warrants:


	2022 Warrants		2024 Warrants		2025 Placement Warrants		2025 Warrants		2026 Warrants		Pre-Funded Warrants		Total
Outstanding as of December 31, 2025		635,703		3,068,417		1,317,771		4,600,587		—		614,380		10,236,858
Issued		—		—		—		—		4,421,518		3,391,164		7,812,682
Outstanding as of March 31, 2026		635,703		3,068,417		1,317,771		4,600,587		4,421,518		4,005,544		18,049,540
Exercise price as of March 31, 2026	$	95.37	$	6.64	$	6.64	$	6.64	$	10.00	$	—

Table of Contents

Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations.

The following discussion and analysis of our financial condition and results of operations is meant to provide material information relevant to an assessment of the financial condition and results of operations of our company, including an evaluation of the amounts and uncertainties of cash flows from operations and from outside resources, so as to allow investors to better view our company from management’s perspective. You should read the following discussion and analysis of our financial condition and results of operations together with our financial statements and related notes appearing elsewhere in this quarterly report and the audited financial information and the notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2025, as filed with the Securities and Exchange Commission (“SEC”) on February 13, 2026 (“Annual Report”).

FORWARD-LOOKING STATEMENTS

This Quarterly Report on Form 10-Q, contains forward-looking statements regarding the expectations of Karyopharm Therapeutics Inc., herein referred to as “Karyopharm,” the “Company,” “we,” or “our,” with respect to the possible achievement of discovery and development milestones, our future discovery and development efforts, including regulatory submissions and approvals, potential inclusion of selinexor in combination with ruxolitinib in relevant compendia, our commercialization efforts, our partnerships and collaborations with third parties, our future operating results and financial position, our ability to continue as a going concern, our business strategy, and other objectives for future operations. We often use words such as “anticipate,” “believe,” “estimate,” “expect,” “intend,” “may,” “plan,” “predict,” “project,” “target,” “potential,” “will,” “would,” “could,” “should,” “continue,” and other words and terms of similar meaning to help identify forward-looking statements, although not all forward-looking statements contain these identifying words. You also can identify these forward-looking statements by the fact that they do not relate strictly to historical or current facts. There are a number of important risks and uncertainties that could cause actual results or events to differ materially from those indicated by forward-looking statements. These risks and uncertainties include, but are not limited to, those described in Part II, Item 1A - Risk Factors of this Quarterly Report on Form 10-Q. As a result of these and other factors, we may not actually achieve the plans, intentions, expectations or results disclosed in our forward-looking statements, and you should not place undue reliance on our forward-looking statements. Our forward-looking statements do not reflect the potential impact of any future acquisitions, mergers, dispositions, joint ventures or investments we may make. We do not assume any obligation to update any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by law.

References to XPOVIO® (selinexor) also refer to NEXPOVIO® (selinexor) when discussing its approval and commercialization in certain countries or territories outside of the U.S.

OVERVIEW

We are a commercial-stage pharmaceutical company pioneering novel cancer therapies and dedicated to the discovery, development and commercialization of first-in-class drugs directed against nuclear export for the treatment of cancer. Our scientific expertise is based upon an understanding of the regulation of intracellular communication between the nucleus and the cytoplasm. We have discovered and are developing and commercializing novel, small molecule XPO1 inhibitor compounds that inhibit the nuclear export protein exportin 1 (“XPO1”). These compounds represent a new class of drug candidates with a novel mechanism of action that have the potential to treat a variety of diseases with high unmet medical need. Our lead asset, XPOVIO® (selinexor), was the first oral XPO1 inhibitor to receive marketing approval, receiving its initial U.S. approval from the U.S. Food and Drug Administration in July 2019, and is currently approved and marketed in the U.S. for the following indications:

•

In combination with bortezomib and dexamethasone for the treatment of adult patients with multiple myeloma who have received at least one prior therapy. Approval in this indication was based on the results from the BOSTON (Bortezomib, Selinexor and Dexamethasone) trial; and

•

In combination with dexamethasone for the treatment of adult patients with relapsed or refractory multiple myeloma who have received at least four prior therapies and whose disease is refractory to at least two proteasome inhibitors, at least two immunomodulatory agents, and an anti-CD38 monoclonal antibody. Approval in this indication was based on the results from the STORM (Selinexor Treatment of Refractory Myeloma) trial.

Our primary focus is on marketing XPOVIO in its currently approved indications as well as developing and seeking regulatory approval of selinexor as an oral agent targeting multiple high unmet need cancer indications, including our lead clinical programs in myelofibrosis and endometrial cancer and our other late-stage clinical program in multiple myeloma. Depending on the data in our Phase 3 myelofibrosis and/or endometrial cancer programs and the availability of capital resources, we plan to explore opportunities to develop our leading next-generation XPO1 inhibitor, eltanexor, in additional myeloproliferative neoplasms and TP53 wild-type tumors.

The commercialization of XPOVIO in the U.S. is currently supported by sales representatives, nurse liaisons, and a market access team, as well as KaryForward®, an extensive patient and healthcare provider support program. Our commercial efforts are also supplemented by patient support initiatives coordinated by our dedicated network of participating specialty pharmacy providers.

Table of Contents

The commercialization of XPOVIO and NEXPOVIO®(selinexor) (the brand name for selinexor in Europe and the United Kingdom) outside of the U.S. is managed by our partners in their respective territories. XPOVIO/NEXPOVIO has received regulatory approvals in various indications in more than 50 territories and countries outside the U.S. and is commercially available in a growing number of countries as our partners continue to secure reimbursement approvals.

RECENT DEVELOPMENTS

Phase 3 SENTRY Trial Topline Data Results

On March 24, 2026, we announced topline data results from our Phase 3 clinical trial to evaluate the efficacy and safety of once-weekly selinexor in combination with ruxolitinib versus placebo plus ruxolitinib in JAK2 inhibitor (“JAKi”)-naive myelofibrosis patients (the “SENTRY Trial”) in which patients were randomized 2:1 to 60 mg of selinexor once weekly plus ruxolitinib or placebo plus ruxolitinib. The ruxolitinib dose was determined based on the patients’ baseline platelet count per the drug’s prescribing information. The SENTRY Trial met the first co-primary endpoint, demonstrating statistically significant improvement in spleen volume reduction of 35% or more for patients treated with the combination of selinexor plus ruxolitinib, with rapid, deep and sustained spleen volume reduction rates seen in the combination arm, but did not meet its second co-primary endpoint in absolute total symptom score. The mean change in absolute total symptom score at week 24 relative to baseline was comparable across the two arms with similar symptom improvement relative to baseline; the difference across the two arms was not statistically significant. In addition, a promising overall survival signal was observed in the topline data, which further reinforces the relevance of XPO1 inhibition in combination with ruxolitinib in frontline myelofibrosis. Further, a greater proportion of patients on the combination arm compared to ruxolitinib alone experienced reductions in variant allele frequency, which may be indicative of an underlying effect on disease biology, raising the potential for disease modification. The combination demonstrated a manageable safety and tolerability profile consistent with the known profile of selinexor and ruxolitinib individually. No new safety signals were observed. Our key near term objectives in advancing our SENTRY program include: engagement with the U.S. Food and Drug Administration (“FDA”) to discuss the data from the SENTRY Trial and our supplemental new drug application filing plan; disclosure of additional data from the Phase 3 SENTRY Trial at an upcoming medical meeting; and potential inclusion of the combination in relevant compendia, which could occur in the second half of 2026.

Other Clinical Trial Updates

We continue to enroll JAKi-naïve myelofibrosis patients in the Phase 2 clinical trial to evaluate the safety and efficacy of selinexor as a monotherapy in patients with JAKi-naïve myelofibrosis with moderate thrombocytopenia (the “SENTRY-2 Trial”). We completed enrollment of the 60 mg cohort of the SENTRY-2 trial and began enrolling patients into the 40 mg cohort. We expect to report topline data from all patients in the 60 mg cohort with at least 24 weeks of follow-up in the second half of 2026.

We have completed enrollment of our global, Phase 3, randomized, double-blind trial evaluating selinexor as a maintenance-only therapy following systemic therapy in patients with TP53 wild-type advanced or recurrent endometrial cancer (the “XPORT-EC-042 Trial”). Approximately 220 patients enrolled in the modified intent-to-treat (“mITT”) population and 257 enrolled in the intent-to-treat population. Enrollment in the mITT population was focused on patients with either proficient mismatch repair status tumors or patients with deficient mismatch repair status tumors who are medically ineligible for checkpoint inhibitors. We expect to report topline data from this event-driven trial in mid-2026.

Patients enrolled in a randomized global Phase 3 trial sponsored by the European Myeloma Network evaluating an all-oral combination of selinexor 40 mg in combination with pomalidomide and dexamethasone versus elotuzumab, pomalidomide, and dexamethasone in patients with previously treated multiple myeloma who received an anti-CD38 in their immediate prior line of therapy (the “EMN29 Trial”). The patients enrolled in this event-driven trial continued to be followed for progression-free survival events contributing towards the primary endpoint. We expect to report topline data from the EMN29 Trial in the second half of 2026.

In March 2026, we met with the FDA regarding the Accelerated Approval of the Diffuse Large B-Cell Lymphoma (“DLBCL”) indication of XPOVIO, which was granted on June 22, 2020 for the treatment of adult patients with relapsed or refractory DLBCL, not otherwise specified, including DLBCL arising from follicular lymphoma, after at least two lines of systemic therapy. The FDA requested and we agreed to voluntarily withdraw the accelerated approval of the DLBCL indication in light of the infeasibility of completing the confirmatory trial, especially considering the evolving treatment landscape, including the availability of new therapeutic options. As a result, we expect to terminate our ongoing company-sponsored trials in this indication. This withdrawal is not due to safety concerns with the DLBCL indication and does not affect the regulatory approval of any other indications for XPOVIO.

Business and Financial Updates

Table of Contents

On February 27, 2026, we entered into the Second Amendment to Credit and Guaranty Agreement (the “Amendment”) with the lenders party thereto and Wilmington Savings Fund Society, FSB, as administrative agent and collateral agent, which amended our Credit and Guaranty Agreement, dated May 8, 2024 (as previously amended, the “Credit Agreement”). On February 27, 2026, we also entered into a Forbearance Agreement (the “Forbearance Agreement”) with (i) all the lenders under the Credit Agreement, (ii) all the holders of our 9.00% Convertible Senior Notes due 2029 (the “New 2029 Notes”) and 9.00% Convertible Senior Notes due 2028 (the “2028 Notes”), and (iii) the investor representative for the investors under our revenue interest financing agreement (collectively, the “Consenting Parties”).

The effectiveness of the Forbearance Agreement was conditioned upon, among other things, the consummation of a sale and issuance of our common stock, in one or more transactions, resulting in proceeds to us of not less than $25.0 million actually received in cash before June 10, 2026 (the “Capital Raise Trigger”). The Capital Raise Trigger was satisfied and the Forbearance Agreement became effective in March 2026 upon receipt of the proceeds from the Private Placement (as defined below). Under the Amendment and the Forbearance Agreement, we can defer certain principal and interest payments until September 2026 and the Consenting Parties agreed not to exercise certain rights and remedies with respect to specified matters, including: (i) payment-related defaults through September 30, 2026 that would result from our non-payment of the interest due on June 30, 2026 for the New 2029 Notes and 2028 Notes and (ii) any defaults that result from a requirement under the indentures of the New 2029 Notes and 2028 Notes for us to have a Minimum Liquidity Covenant Amount greater than the lesser of (i) $10.0 million plus 50% of the net cash proceeds received from certain debt and equity issuances and (ii) $25.0 million through October 10, 2026. After October 10, 2026, the minimum liquidity covenant will require minimum consolidated liquidity of $25.0 million.

On March 24, 2026, we entered into a Securities Purchase Agreement with RA Capital Healthcare Fund, L.P. (“RA Capital Management”) pursuant to which we issued and sold in a private placement (the “Private Placement”): (i) 1,030,354 shares of common stock, (ii) pre-funded warrants to purchase up to 3,391,164 shares of common stock, and (iii) accompanying warrants to purchase 4,421,518 shares of common stock with an exercise price of $10.00 per share (the “2026 Warrants”) for aggregate net proceeds of $26.9 million. The 2026 Warrants are exercisable until 30 days following our public announcement of topline data results from our Phase 3 XPORT-EC-042 clinical trial of selinexor in patients with endometrial cancer and the pre-funded warrants do not expire. As of March 31, 2026, none of these warrants have been exercised.

In addition, in March 2026, we issued and sold an aggregate of 2,994,441 shares of Common Stock under our Open Market Sale AgreementSM, by and between us and Jefferies LLC, dated February 17, 2023 for total proceeds, net of sales commissions, of approximately $19.8 million.

As of March 31, 2026, we had an accumulated deficit of $1.8 billion. We had operating losses of $26.8 million and $33.3 million for the three months ended March 31, 2026 and 2025, respectively. We recognized total revenue of $35.1 million and $30.0 million for the three months ended March 31, 2026 and 2025, respectively, including $29.2 million and $21.1 million of XPOVIO net product revenue, respectively, and $5.9 million and $9.0 million of license revenue, respectively. As of March 31, 2026, we had $90.9 million in cash and cash equivalents. Based on our current business plan and current capital resources, combined with the uncertainty regarding the availability of additional funding or other strategic alternatives and considering our debt service obligations and financial covenant to maintain minimum liquidity, we have concluded that there is substantial doubt regarding our ability to continue as a going concern within one year after the date the accompanying consolidated financial statements are issued. See “Liquidity, Capital Resources, and Going Concern” below for a further discussion of our liquidity and the conditions that raise substantial doubt regarding our ability to continue as a going concern.

CRITICAL ACCOUNTING ESTIMATES

We believe that several accounting policies are important to understanding our historical and future performance. We refer to these policies as “critical” because these specific areas generally require us to make judgments and estimates about matters that are uncertain at the time we make the estimate, and different estimates - which also would have been reasonable - could have been used, which would have resulted in different financial results. There have been no changes to the critical accounting estimates we identified in Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations in our Annual Report.

Table of Contents

RESULTS OF OPERATIONS

The following table summarizes our results of operations (in thousands, except for percentages):


	For the Three Months Ended March 31,
	2026			2025			$ Change			% Change
Product revenue, net	$	29,163		$	21,054		$	8,109			39	%
License and other revenue		5,903			8,961			(3,058	)		(34	)%
Total revenue		35,066			30,015			5,051			17	%
Operating expenses:
Cost of sales		1,345			1,301			44			3	%
Research and development		33,797			34,618			(821	)		(2	)%
Selling, general and administrative		26,684			27,352			(668	)		(2	)%
Loss from operations		(26,760	)		(33,256	)		6,496			(20	)%
Other income, net		4,369			9,830			(5,461	)		(56	)%
Loss before income taxes		(22,391	)		(23,426	)		1,035			(4	)%
Income tax provision		(1	)		(36	)		35			(97	)%
Net loss	$	(22,392	)	$	(23,462	)	$	1,070			(5	)%

Product Revenue, net (in thousands, except for percentages)


	For the Three Months Ended March 31,
	2026		2025		$ Change		% Change
Product revenue, net	$	29,163	$	21,054	$	8,109		39	%

To date, our only source of product revenue has been from the U.S. sales of XPOVIO. Net product revenue for the three months ended March 31, 2026 increased by $8.1 million compared to the same period in 2025. This increase was primarily attributable to an unusually high product return reserve recorded in the prior-year period, which reduced net revenue in that period, as well as lower gross-to-net discounts, specifically a decrease in chargebacks and Medicare rebate reserve in the first quarter of 2026 compared to the first quarter of 2025.

License and Other Revenue (in thousands, except for percentages)


	For the Three Months Ended March 31,
	2026		2025		$ Change			% Change
Menarini Group (“Menarini”)	$	1,828	$	8,196	$	(6,368	)		(78	)%
Antengene Therapeutics Limited (“Antengene”)		499		652		(153	)		(23	)%
Other		3,576		113		3,463		>100%
Total license and other revenue	$	5,903	$	8,961	$	(3,058	)		(34	)%

License and other revenue for the three months ended March 31, 2026 decreased by $3.1 million as compared to the three months ended March 31, 2025, primarily due to a decrease of $7.0 million of reimbursement revenue from Menarini for development-related expenses as their obligation to reimburse us expired on December 31, 2025. This decrease was partially offset by an increase in milestone-related revenue from our other partners in the three months ended March 31, 2026, primarily due to a $3.5 million milestone payment under a licensing agreement with a privately-held biotech company related to the research, development and commercialization of verdinexor for the treatment of cancer in certain animals.

We expect license and other revenue to decrease in the second quarter of 2026 as compared to the first quarter of 2026, as we do not anticipate recognizing any milestone-related revenue.

Table of Contents

Operating Expenses (in thousands, except for percentages)


	For the Three Months Ended March 31,
	2026		2025		$ Change			% Change
Cost of sales	$	1,345	$	1,301	$	44			3	%
Research and development		33,797		34,618		(821	)		(2	)%
Selling, general and administrative		26,684		27,352		(668	)		(2	)%
Total operating expenses	$	61,826	$	63,271	$	(1,445	)		(2	)%

Cost of Sales

Cost of sales for the three months ended March 31, 2026 and 2025 were relatively consistent.

Research and Development Expenses (in thousands, except for percentages)


	For the Three Months Ended March 31,
	2026		2025		$ Change			% Change
Clinical trial and related costs:
Selinexor in myelofibrosis	$	10,917	$	11,417	$	(500	)		(4	)%
Selinexor in endometrial cancer		4,590		4,226		364			9	%
Selinexor in multiple myeloma		1,809		1,925		(116	)		(6	)%
Other programs		342		578		(236	)		(41	)%
Non-program specific clinical trial and related costs		1,027		1,223		(196	)		(16	)%
Total clinical trial and related costs		18,685		19,369		(684	)		(4	)%
Unallocated costs:
Personnel		10,724		10,510		214			2	%
Consulting, professional and other		3,502		3,824		(322	)		(8	)%
Stock-based compensation		886		915		(29	)		(3	)%
Total unallocated costs		15,112		15,249		(137	)		(1	)%
Total research and development expenses	$	33,797	$	34,618	$	(821	)		(2	)%

At any one time, we have a number of ongoing clinical development programs that we are conducting independently or in collaboration with third parties. We track our external clinical trial and related costs on a program-by-program basis. Our major programs include our lead clinical programs in myelofibrosis and endometrial cancer and our other late-stage clinical program in multiple myeloma. To the extent that external clinical trial and related costs are not attributable to a major program, they are included in “Other programs” and to the extent external clinical trial and related costs cannot be allocated to a specific program, they are included in “Non-program specific clinical trial and related costs.” We also have unallocated research and development costs, which we do not track on a program-by-program basis. These costs represent expenses incurred across multiple programs or to support our general research and development operations.

Research and development expenses for the three months ended March 31, 2026 were relatively consistent as compared to the three months ended March 31, 2025. If the topline data of our trials is positive or we are able to submit a supplemental New Drug Application (“sNDA”), we expect our research and development expenses will increase, primarily due to costs associated with regulatory filings.

Selling, General and Administrative Expenses (in thousands, except for percentages)


	For the Three Months Ended March 31,
	2026		2025		$ Change	% Change
Personnel costs	$	14,168	$	14,657

Karyopharm Therapeutics Inc. 10-Q