UNITED ~~STATESSECURITIES AND EXCHANGE COMMISSIONWASHINGTON, D.C. 20549~~STATES

~~FORM~~SECURITIES ~~8-K~~AND EXCHANGE COMMISSION

~~CURRENT~~WASHINGTON, ~~REPORT~~D.C. 20549

~~Pursuant~~FORM ~~to Section 13 or 15(d) of the Securities Exchange Act of 1934~~8-K

~~Date~~CURRENT ~~of Report (Date of earliest event reported): October 31, 2025~~REPORT

~~LANTHEUS~~Pursuant ~~HOLDINGS,~~to ~~INC.~~Section 13 or 15(d)

~~(Exact name~~ of ~~Registrant~~the asSecurities ~~Specified~~Exchange inAct ~~Its~~of ~~Charter)~~1934

Delaware	001-36569	35-2318913
(State or Other Jurisdictionof Incorporation)	(Commission File Number)	(IRS EmployerIdentification No.)
201 Burlington RoadSouth Building
Bedford, Massachusetts		01730
(Address of Principal Executive Offices)		(Zip Code)

Date of Report (Date of earliest event reported): November 6, 2025

~~Registrant’s~~ ~~Telephone~~LANTHEUS ~~Number~~HOLDINGS, ~~Including~~INC. ~~Area Code: (978) 671-8001~~

~~Not~~(Exact ~~Applicable~~name of Registrant as Specified in Its Charter)

(Former Name or Former Address, if Changed Since Last Report)

Delaware

001-36569

35-2318913

(State or Other Jurisdiction

of Incorporation)

(Commission

File Number)

(IRS Employer

Identification No.)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:


201 Burlington Road South Building
Bedford, Massachusetts		01730
(Address of Principal Executive Offices)		(Zip Code)

~~☐Written~~Registrant’s ~~communications~~Telephone ~~pursuant~~Number, toIncluding ~~Rule~~Area ~~425~~Code: ~~under the Securities Act~~ (~~17 CFR 230.425~~978) 671-8001

~~☐Soliciting~~(Former ~~material~~Name ~~pursuant~~or toFormer ~~Rule~~Address, ~~14a-12~~if ~~under~~Changed ~~the~~Since ~~Exchange~~Last ~~Act (17 CFR 240.14a-12~~Report)

~~☐Pre~~Check the appropriate box below if the Form 8-~~commencement~~K ~~communications~~filing ~~pursuant~~is intended to ~~Rule~~simultaneously ~~14d-2(b)~~satisfy ~~under~~the filing obligation of the ~~Exchange~~registrant ~~Act~~under ~~(17~~any ~~CFR~~of ~~240.14d-2(b))~~the following provisions:

☐~~Pre-commencement~~ Written communications pursuant to Rule ~~13e-4(c)~~425 under the ~~Exchange~~Securities Act (17 CFR ~~240~~230.~~13e-4(c~~425))

~~Securities~~☐ ~~registered~~Soliciting material pursuant to ~~Section~~Rule 14a-12~~(b)~~ ofunder the Exchange Act: (17 CFR 240.14a-12)

Title of each class		TradingSymbol(s)		Name of each exchange on which registered
Common stock, par value $0.01 per share		LNTH		The Nasdaq Global Market

☐	Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

~~Indicate~~☐ byPre-commencement ~~check~~communications ~~mark~~pursuant ~~whether~~to ~~the registrant is an emerging growth company as defined in~~ Rule ~~405 of the Securities Act of 1933~~ 13e-4(~~§ 230.405 of this chapter~~c) orunder ~~Rule 12b-2 of~~ the ~~Securities~~ Exchange Act of(17 ~~1934~~CFR (§ 240.~~12b~~13e-~~2 of this chapter~~4(c). )

~~Emerging~~Securities ~~growth~~registered ~~company~~pursuant ☐to Section 12(b) of the Act:

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. ☐

Title of each class

Trading

Symbol(s)

Name of each exchange

on which registered

Common stock, par value $0.01 per share

LNTH

The Nasdaq Global Market

~~Item~~Indicate 2by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.02405 ~~Results~~of this chapter) or Rule 12b-2 of ~~Operations~~the ~~and~~Securities ~~Financial~~Exchange ~~Condition~~Act of 1934 (§ 240.12b-2 of this chapter).

OnEmerging ~~November~~growth 6,company 2025, Lantheus Holdings, Inc. (the “Company”) announced via press release its financial results as of and for the three and nine months ended September 30, 2025. A copy of that press release is being furnished as Exhibit 99.1 and is hereby incorporated by reference. ☐

~~The~~If ~~information~~an ~~furnished~~emerging ~~pursuant~~growth ~~to this Item 2.02~~company, ~~including~~indicate ~~Exhibit~~by ~~99.1,~~check ~~shall~~mark ~~not~~if bethe ~~deemed~~registrant ~~“filed”~~has ~~for~~elected ~~purposes~~not ofto ~~Section~~use ~~18 of~~ the ~~Securities~~extended ~~Exchange~~transition ~~Act~~period offor ~~1934,~~complying aswith ~~amended~~any ~~(the~~new ~~“Exchange Act”),~~ or ~~otherwise~~revised ~~subject~~financial toaccounting ~~the~~standards ~~liabilities~~provided ~~under~~pursuant ~~that Section and shall not be deemed~~ to ~~be incorporated by reference into any filing of the Company under the Securities Act of 1933, as amended~~ Section 13(~~the “Securities Act”~~a), orof the Exchange Act~~, except as shall be expressly set forth by specific reference in such filing~~. ☐

Item 5.02

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers

OnEffective ~~November~~as of November 6, 2025, ~~the~~and ~~Company~~in connection with his previously announced ~~that~~retirement, ~~Brian~~Lantheus ~~Markison~~Holdings, Inc. (the “Company’s”) ~~Chief~~entered ~~Executive~~into ~~Officer~~a ~~and~~consulting aagreement ~~member~~with ofBrian Markison, the Company’s ~~board~~Chief ofExecutive ~~directors~~Officer (the “~~Board~~Consulting Agreement”), ~~notified~~for ~~the~~consulting ~~Board~~services onthat ~~November~~will 2commence on January 1, ~~2025~~2026, ~~that~~pursuant to which he will ~~retire~~serve ~~from~~as an advisor to the Company ~~effective~~from ~~December~~January 1, 2026 through March 31, ~~2025~~2026, (with the ~~“Effective~~parties ~~Date”)~~having the option to extend the consulting period. In ~~connection~~Effective ~~with~~as ~~his~~of ~~retirement~~November 6, ~~and~~2025, inMr. Markison ~~accordance~~also ~~with~~entered ~~the~~into ~~terms~~a ofretirement ~~his~~and ~~employment~~separation agreement (the “Retirement Agreement”) with the Company~~, Mr~~. ~~Markison~~Pursuant ~~will~~to ~~also~~the ~~resign~~Retirement ~~from~~Agreement, the ~~Board~~Company onwill ~~the~~continue ~~Effective~~payment ~~Date.~~ of Mr. Markison’s ~~decision~~base tosalary ~~retire~~through ~~from~~December 31, ~~all~~2025 ~~positions~~(the ~~held~~“Retirement atDate”) ~~the~~and ~~Company~~within is60 ~~not~~days ~~related~~of tothe ~~any~~Retirement ~~disagreement~~Date ~~with~~will ~~the~~pay ~~Company~~him ona ~~any~~lump ~~matter~~sum ~~relating~~amount equal to ~~its~~his ~~operations,~~earned ~~policies,~~annual orcash ~~practices. Mr.~~bonus ~~Markison~~in ~~has~~respect ~~agreed~~of to2025, ~~serve~~if asany, abased ~~strategic~~on ~~advisor~~actual toCompany performance as determined in the ~~Company~~ordinary ~~through~~course atand ~~least~~consistent ~~March~~with ~~31,~~past ~~2026~~practice.

~~The~~Pursuant ~~Company~~to ~~has~~the ~~also~~Consulting ~~announced that Mary Anne Heino~~Agreement, ~~the~~subject ~~Chair~~to ofcontinued ~~the~~compliance ~~Board,~~with ~~has~~customary ~~been~~restrictive ~~appointed~~covenants ~~Executive~~in ~~Chair~~favor of the Company ~~effective on November 7~~, ~~2025~~Mr. Markinson ~~(the “Appointment Date”) and~~ will ~~serve~~receive asan ~~the~~advisory ~~Company’s~~fee ~~principal~~in ~~executive~~an ~~officer~~amount asequal ofto ~~the Appointment Date. In addition~~$83,333 ~~the~~per ~~Board appointed Ms~~month. ~~Heino~~Pursuant asto the ~~Company’s~~Retirement ~~Interim Chief Executive Officer effective on January 1~~Agreement, ~~2026. Ms.~~his ~~Heino,~~outstanding ~~65,~~equity ~~has~~awards ~~served~~will ascontinue ato ~~member~~vest ofthrough the ~~Board~~Retirement ~~since~~Date ~~August~~and, ~~2015~~thereafter, ~~and~~will ~~became~~be ~~the~~subject ~~Chair~~to of the ~~Board~~retirement ~~and~~features aas ~~member~~set offorth ~~the Science and Technology Committee~~ in ~~March~~each ~~2024. She~~such ~~previously~~award, ~~served~~as described in the ~~following roles at the~~ Company~~: Chief~~’s ~~Executive~~definitive ~~Officer~~proxy ~~from~~statement ~~August~~on ~~2015~~Schedule ~~until~~14A ~~March~~filed 1,with ~~2024;~~the ~~President~~United ~~from~~States ~~August~~Securities ~~2015 until March 2023; Chief Operating Officer from March 2015 until August 2015;~~ and ~~Chief~~Exchange ~~Commercial~~Commission ~~Officer~~on ~~from April 2013 (when she joined the Company) until~~ March 21, ~~2015~~2025.

~~Ms.~~The ~~Heino~~foregoing ~~was~~description ~~not~~of ~~selected~~the asterms ~~Executive~~of ~~Chair~~the orConsulting ~~Interim~~Agreement ~~Chief~~and ~~Executive~~the ~~Officer~~Retirement ~~pursuant~~Agreement todoes ~~any~~not ~~arrangement~~purport orto ~~understanding~~be ~~between~~complete ~~her~~ and ~~any~~is ~~other~~qualified ~~person.~~in ~~There~~its ~~are~~entirety noby ~~related~~reference ~~party~~to ~~transactions between~~ the ~~Company~~text ~~and~~of ~~Ms.~~the ~~Heino,~~Consulting ~~except~~Agreement ~~that~~and ~~she previously entered into an indemnification agreement with~~ the ~~Company~~Retirement inAgreement, ~~connection~~copies ~~with her service as a member~~ of ~~the~~which ~~Board that~~ will ~~remain~~be infiled ~~effect.~~as ~~There~~an ~~are~~exhibit noto ~~family~~the ~~relationships~~Company’s ~~between~~Annual ~~Ms.~~Report ~~Heino~~on ~~and~~Form 10-K for ~~any~~the ~~director~~fiscal oryear ~~executive~~ending ~~officer~~December 31, ~~of the Company~~2025.

OnSIGNATURES October 31, 2025, Paul Blanchfield, President, notified the Company that he has accepted a role at another company and is leaving Lantheus, effective November 7, 2025. In addition, Amanda Morgan will return from leave and continue in her role as Chief Commercial Officer, reporting directly to Ms. Heino.

InPursuant connection with her appointment as Executive Chair and continuing through her tenure as Interim Chief Executive Officer, Ms. Heino will receive $83,333 per month in base salary, which reflects an annual rate of $1,000,000. She will also be eligible to ~~receive~~the arequirements ~~bonus in respect~~ of ~~fiscal~~the ~~2026~~Securities ~~with~~Exchange aAct ~~target~~ of ~~110% of her base salary~~1934, which shall be prorated based on her period of service as Interim Chief Executive Officer. In addition, Ms. Heino will be granted equity awards with an aggregate grant date fair value of $1,500,000 on November 13, 2025 (the ~~“Grant~~registrant ~~Date”). The~~has ~~equity~~duly ~~awards~~caused ~~will~~this ~~consist~~report ~~of 50% in Black-Scholes value for options~~ to ~~purchase~~be ~~the~~signed ~~Company’s common stock with an exercise price equal to the closing price of the common stock~~ on ~~the~~its ~~Grant~~behalf ~~Date~~by ~~and 50% restricted stock units, all of which will vest in full on~~ the ~~first~~undersigned ~~anniversary~~hereunto ofduly ~~the Grant Date, so long as Ms~~authorized. ~~Heino continues to provide services to the Company through such date.~~

~~Item~~LANTHEUS 7HOLDINGS, INC.01 ~~Regulation~~By: FD/s/ ~~Disclosure~~Daniel M. Niedzwiecki Name: Daniel M. Niedzwiecki Title: Chief Administrative Officer and General Counsel

OnDate: November 6 12, 2025, the Company issued a press release announcing its leadership transition plan. A copy of the press release is being furnished with this Current Report on Form 8-K as Exhibit 99.2 and is incorporated herein by reference.

The information in this Item 7.01, including Exhibit 99.2, shall not be deemed “filed” for purposes of Section 18 of the Exchange Act or otherwise subject to the liabilities under that Section and shall not be deemed to be incorporated by reference into any filing of the Company under the Securities Act or the Exchange Act, except as shall be expressly set forth by specific reference in such filing.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits

Exhibit No.		Description
99.1*		Press release of Lantheus Holdings, Inc. dated November 6, 2025, entitled “Lantheus Reports Third Quarter 2025 Financial Results and Provides Business Update”
99.2*		Press release of Lantheus Holdings, Inc. dated November 6, 2025, entitled “Lantheus Announces Leadership Transition Plan”
104		Cover Page Interactive Data File (embedded within the Inline XBRL document)

* Exhibits 99.1 and 99.2 attached hereto are being furnished and shall not be deemed “filed” for purposes of Section 18 of the Exchange Act, as amended, or otherwise subject to the liabilities of that section, nor shall such information be deemed incorporated by reference in any filing under the Securities Act or the Exchange Act, except as shall be expressly set forth by specific reference in such filing.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

LANTHEUS HOLDINGS, INC. By: /s/ Daniel M. Niedzwiecki Name: Daniel M. Niedzwiecki Title: Chief Administrative Officer and General Counsel

Date: November 6, 2025

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