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): June 17, 2026
SPERO THERAPEUTICS, INC.
(Exact name of registrant as specified in its charter)
| Delaware | 001-38266 | 46-4590683 | ||
| (State or other jurisdiction of incorporation) | (Commission File Number) | (I.R.S. Employer Identification No.) |
| 675 Massachusetts Avenue, 14th Floor | ||
| 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 | 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 7.01 | Regulation FD Disclosure |
On June 17, 2026, Spero Therapeutics, Inc. (the “Company”) issued a press release announcing that the U.S. Food and Drug Administration (“FDA”) has granted approval for Utebzi (tebipenem pivoxil), an oral antibiotic for the treatment of complicated urinary tract infections (“cUTIs”), including pyelonephritis, caused by certain susceptible pathogens in adult patients who have limited or no alternative oral treatment option.
The full text of the press release issued in connection with the announcement is furnished as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated into this Item 7.01 by reference.
The information in this Item 7.01 and Exhibit 99.1, is intended to be furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section or sections 11 and 12(a)(2) of the Securities Act of 1933, as amended (the “Securities Act”), nor shall it be deemed incorporated by reference in any filing under the Securities Act or the Exchange Act, except as expressly set forth by specific reference in such filing.
| Item 8.01 | Other Events. |
On June 17, 2026, the Company issued a press release announcing that the FDA has granted approval for Utebzi (tebipenem pivoxil), an oral antibiotic for the treatment of cUTIs, including pyelonephritis, caused by certain susceptible pathogens in adult patients who have limited or no alternative oral treatment option. This is the first and only oral carbapenem antibiotic approved for these patients. This approval is a result of GSK’s development and exclusive global licensing agreement (excluding select Asian territories) with the Company. FDA approval was received in advance of FDA-assigned Prescription Drug User Fee Act (“PDUFA”) date of June 18, 2026.
| Item 9.01 | Financial Statements and Exhibits |
| (d) | Exhibits |
| Exhibit No. | Description | |
| 99.1 | Press release issued by Spero Therapeutics, Inc. on June 17, 2026 | |
| 104 | Cover Page Interactive Data File (embedded within the Inline XBRL document and incorporated as Exhibit 101) | |
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: June 22, 2026 | SPERO THERAPEUTICS, INC. | |||||
| By: | /s/ Esther Rajavelu | |||||
| Esther Rajavelu | ||||||
| Chief Executive Officer, Chief Financial Officer and Chief Business Officer | ||||||