UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of The Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): ~~May 28~~June 12, 2025

SPERO THERAPEUTICS, INC.

(Exact name of registrant as specified in its charter)

Delaware	001-38266	46-4590683
(State or other jurisdictionof incorporation)	(CommissionFile Number)	(I.R.S. EmployerIdentification No.)
(State or other jurisdiction of incorporation)	(Commission File Number)	(I.R.S. Employer Identification No.)


675 Massachusetts Avenue, 14^thFloor
Cambridge, Massachusetts				02139
(Address of principal executive offices)				(Zip Code)

Registrant’s telephone number, including area code (857) 242-1600

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:

☐	Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐	Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

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

☐	Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Title of each class		TradingSymbol(s)		Name of each exchangeon which registered
Common Stock, $0.001 par value		SPRO		The Nasdaq Global Select Market

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, $0.001 par value

SPRO

The Nasdaq Global Select Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

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. ☐

Item 75.0102 ~~Regulation~~Departure FDof ~~Disclosure.~~Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers

OnAt ~~May 28,~~the 2025, Annual Meeting of Stockholders (the “Annual Meeting”) of Spero Therapeutics, Inc. (the “Company”) ~~issued~~held aon ~~press~~June 12, ~~release~~2025, ~~announcing that~~ the ~~pivotal~~Company’s ~~Phase~~stockholders 3approved ~~PIVOT-PO~~an ~~trial~~amendment ~~evaluating~~to ~~tebipenem~~the ~~HBr,~~Company’s an2017 ~~investigational~~Stock ~~oral~~Incentive ~~treatment~~Plan, ~~for~~as ~~complicated~~amended ~~urinary tract infections~~ (the “~~cUTIs~~2017 Plan”), ~~including~~to ~~pyelonephritis,~~increase ~~met~~the ~~its~~total ~~primary~~number ~~endpoint~~of ~~and~~shares ~~will~~of ~~stop~~the ~~early~~Company’s ~~for~~common ~~efficacy.~~stock Aauthorized ~~copy~~for ofissuance under the ~~press~~2017 ~~release~~Plan isby ~~furnished~~3,000,000 ~~as Exhibit 99~~shares.1 ~~herewith.~~

~~The~~A ~~information~~detailed ~~included~~summary ~~under~~of ~~this~~the ~~Item~~material ~~7.01,~~features ~~including Exhibit 99.1, shall not be deemed “filed” for purposes~~ of ~~Section 18 of~~ the ~~Securities~~2017 ~~Exchange Act of 1934~~Plan, as amended ~~(the “Exchange Act”)~~, oris ~~otherwise~~set ~~subject~~forth toin the ~~liability~~Company’s ofdefinitive ~~that~~proxy ~~section,~~statement ~~nor~~(the ~~shall~~“Proxy itStatement”) befor ~~deemed~~its ~~incorporated~~Annual byMeeting ~~reference~~filed inwith ~~any filing under~~ the Securities ~~Act~~and ofExchange ~~1933,~~Commission ason ~~amended~~April 28, ~~or the Exchange Act~~2025, ~~whether~~which ~~made~~summary ~~before~~is orincorporated ~~after~~herein ~~the date hereof, except as expressly set forth~~ by ~~specific~~ reference ~~in such filing to this Current Report on Form 8-K~~.

Item 85.0107 ~~Other~~Submission ~~Events.~~of Matters to a Vote of Stockholders

On ~~May~~June 2812, 2025, the Company ~~along~~held ~~with~~ its ~~development~~Annual ~~partner~~Meeting. ~~GSK~~Of ~~plc (“GSK”) announced that~~ the ~~pivotal Phase 3 PIVOT-PO trial evaluating tebipenem HBr~~55, ~~an investigational oral treatment for cUTIs~~910,641 ~~including~~shares ~~pyelonephritis,~~of ~~met~~common ~~its~~stock ~~primary~~issued ~~endpoint~~ and ~~will~~outstanding ~~stop~~and ~~early~~eligible ~~for~~to ~~efficacy.~~vote ~~The~~as ~~decision~~of ~~follows~~the arecord ~~recommendation~~date ~~from~~of anApril 21, ~~Independent~~2025, ~~Data~~a ~~Monitoring~~quorum ~~Committee~~of ~~(“IDMC”)~~40,015,633 ~~that~~shares, ~~completed~~or aapproximately ~~pre-specified~~71.57% ~~interim analysis~~ of ~~data~~the ~~from~~outstanding 1shares,~~690~~ ~~patients~~were ~~enrolled~~present in ~~the~~person ~~trial~~or by proxy.

The ~~Phase~~following 3actions ~~PIVOT-PO~~were ~~trial~~taken met the primary endpoint of non-inferiority of tebipenem HBr compared to intravenous imipenem-cilastatin in hospitalized adult patients with cUTI, including pyelonephritis, on overall response (composite of clinical cure plus microbiological eradication) at the ~~test-of-cure~~Annual ~~visit.~~Meeting: The IDMC review did not identify any new safety concerns beyond what has been reported in other studies with tebipenem, with diarrhea and headache as the two most reported adverse events. GSK plans to work with U.S. regulatory authorities to include the data as part of a filing in the second half of 2025.

~~Forward~~1. ~~Looking~~The ~~Statements~~following nominees were reelected to serve on the Company’s board of directors as Class II directors until the Company’s 2028 annual meeting of stockholders, based on the following votes:

This Current Report on Form 8-K contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended, including, without limitation, statements regarding the timing, progress and results of the Company Phase 3 PIVOT-PO trial; the planned NDA filing for tebipenem HBr and the timing thereof. In some cases, forward-looking statements may be identified by terms such as “may,” “will,” “should,” “expect,” “plan,” “aim,” “anticipate,” “could,” “intent,” “target,” “project,” “contemplate,” “believe,” “estimate,” “predict,” “potential” or “continue,” the negative of these terms or other similar expressions. Any forward-looking statements in this press release are based on management’s current expectations and beliefs and are subject to a number of important risks, uncertainties and other factors that may cause actual results to differ materially from those indicated by such forward-looking statements, including the factors set forth in the Company’s periodic filings with the Securities and Exchange Commission. Investors are cautioned not to place undue reliance on such forward-looking statements, which speak only as of the date of this Current Report on Form 8-K. The Company undertakes no obligation to publicly update any forward-looking statement, whether as a result of new information, future events or otherwise. The forward-looking statements included in this Current Report on Form 8-K represent the Company’s views only as of the date hereof and should not be relied upon as representing its views as of any subsequent date. Except as required by law, the Company explicitly disclaims any obligation to update any forward-looking statements.


Name	Votes For	Votes Withheld	Broker Non-Votes
Frank E. Thomas	25,722,977	449,223	13,843,433
Patrick Vink, M.D.	23,247,371	2,924,829	13,843,433
Esther Rajavelu	25,678,198	494,002	13,843,433

~~Item 9~~2.01 ~~Financial~~The ~~Statements~~selection ~~and~~of ~~Exhibits~~PricewaterhouseCoopers LLP as the Company’s independent registered public accounting firm for the fiscal year ending December 31, 2025 was ratified, based on the following votes:

(d) Exhibits


Votes For	Votes Against	Votes Abstained	Broker Non-Votes
39,837,359	174,980	3,294	N/A

Exhibit No.		Description
99.1		Press release issued by Spero Therapeutics, Inc. on May 28, 2025
104		Cover Page Interactive Data File (embedded within the Inline XBRL document and incorporated as Exhibit 101)

The advisory vote of the compensation of the Company’s named executive officers, as described in the Proxy Statement, was approved, based on the following votes:


Votes For	Votes Against	Votes Abstained	Broker Non-Votes
25,178,672	638,744	354,784	13,843,433

The amendment to the 2017 Plan to increase the total number of shares of common stock authorized for issuance thereunder by 3,000,000 shares, was approved, based on the following votes:


Votes For	Votes Against	Votes Abstained	Broker Non-Votes
22,965,487	3,154,609	52,104	13,843,433

SIGNATURE

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.

Date: May 28, 2025	SPERO THERAPEUTICS, INC.
Date: June 18, 2025		SPERO THERAPEUTICS, INC.
	~~By:~~	~~/s/ Esther Rajavelu~~By:	/s/ Esther Rajavelu
		~~Esther Rajavelu~~	Esther Rajavelu
		~~Chief Executive Officer, Chief Financial Officer and Chief Business Officer~~	Chief Executive Officer, Chief Financial Officer and Chief Business Officer

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