Every 8-K that Spero Therapeuti (SPRO) has filed with the SEC in the last 24 months is listed below, newest first, and each one links through to the document itself with the summary and the scores our analysis gives it.
A 8-K covers material events a company has to report between its quarterly reports, so if you follow SPRO and want that one kind of document rather than the whole filing history, this is the page to keep. The company's other filings, of every form, are on the full SPRO filings page.
Spero Therapeutics, Inc. (SPRO) entered into an Open Market Sale Agreement with Jefferies LLC on August 28, 2026, establishing an at-the-market equity program. Once its new Form S-3 universal shelf registration statement for up to $300,000,000 of securities is declared effective, the company may sell up to $100,000,000 of common stock through Jefferies under this agreement.
Sales, if any, will be made as at-the-market offerings, with Jefferies earning up to 3.0% of aggregate gross proceeds as sales agent. On the same date, Spero terminated its prior Cantor Fitzgerald Controlled Equity Offering Sales Agreement, which had allowed up to $75,000,000 of sales; no shares were sold under that program in 2024 or 2025 and no termination penalties were incurred.
Spero Therapeutics reported second quarter 2026 results and provided a business update. The company highlighted three key milestones: U.S. FDA approval of Utebzi (tebipenem pivoxil), advancement of its new immunology program SP001 toward Phase 2, and a $105 million non-recourse, non-dilutive royalty financing.
For the quarter ended June 30, 2026, Spero reported no revenues, compared with $14.2 million in total revenues in the same quarter of 2025, reflecting the absence of prior grant and related-party collaboration revenue. Operating expenses were $9.9 million, versus $16.6 million a year earlier, driven by lower research and development spending.
Net loss for the quarter was $9.6 million (basic and diluted net loss per share of $0.16), compared with a net loss of $1.7 million (per share $0.03) in the prior-year quarter. As of June 30, 2026, cash and cash equivalents totaled $50.8 million, up from $40.3 million at December 31, 2025. Total assets were $52.8 million and stockholders’ equity was $44.2 million. The company continues to position SP001, a third-generation Fc-silent anti-CD40L monoclonal antibody, for development in IgG4-related and other immune-mediated diseases.
Spero Therapeutics entered an exclusive license with Innovent Biologics for SP001, a third-generation Fc-silent anti-CD40L monoclonal antibody. Spero receives a worldwide license outside mainland China, Hong Kong, Macau and Taiwan and grants Innovent exclusive rights in that territory. Spero will pay Innovent a $35.0 million upfront fee, up to approximately $1.05 billion in development, regulatory and commercial milestones, and tiered royalties on net sales, and has agreed to file a U.S. IND for a Licensed Product within 12 months and use commercially reasonable efforts to develop and commercialize at least one indication in major markets.
On July 8, 2026, Spero also completed a non-recourse royalty financing tied to tebipenem HBr (Utebzi) economics under its GSK license. A special-purpose subsidiary issued senior secured notes with $105,000,000 aggregate principal, a 10% annual interest rate and nine-year maturity, subject to a $3,150,000 original issue discount, payable primarily from GSK milestone and royalty payments. A related agreement sold 65% of GSK milestone and royalty proceeds arising after repayment of the notes for $1,575,000, with Spero retaining 35%. The company estimates that net proceeds from this royalty financing, together with existing cash and cash equivalents, will fund operations into the second half of 2029.
SP001 (IBI355) has completed two Phase 1 studies in healthy volunteers and a Phase 1b multiple-ascending-dose trial in Sjögren’s disease, showing a generally benign safety profile and signals of disease-activity improvement. Spero currently expects to initiate a Phase 2 trial in IgG4-related disease in the second quarter of 2027, while Innovent plans a Phase 2 trial in Sjögren’s disease in China by early 2027, with potential expansion of SP001 into additional autoimmune and inflammatory indications.
Spero Therapeutics, Inc. held its 2026 annual meeting of stockholders, where stockholders approved a new 2026 Stock Incentive Plan covering up to 12,895,866 shares of common stock. This plan will be used for future equity awards to employees, directors, and other service providers.
Stockholders also approved an amendment to the Amended and Restated Certificate of Incorporation to increase authorized common stock from 120,000,000 shares to 240,000,000 shares, expanding the capacity for future issuances. A quorum of 41,061,190 shares, or about 70.91% of the 57,901,493 shares outstanding as of April 24, 2026, was present, and director nominees and other proposals received the required support.
Spero Therapeutics announced that the FDA has approved Utebzi (tebipenem pivoxil), an oral antibiotic for adults with complicated urinary tract infections (cUTIs), including pyelonephritis, who have limited or no alternative oral options. This is the first and only oral carbapenem antibiotic approved for these patients in the US.
The approval stems from a global development and exclusive licensing agreement with GSK and was granted ahead of the Prescription Drug User Fee Act date of June 18, 2026. Phase III PIVOT-PO data showed oral tebipenem pivoxil was non-inferior to intravenous imipenem-cilastatin, with a generally similar safety profile.
Spero Therapeutics reported first quarter 2026 results and updated progress on its tebipenem HBr antibiotic program. Revenue was $258,000, down from $5.874 million a year earlier, reflecting lower grant and collaboration revenue. Operating expenses fell sharply to $7.796 million from $20.605 million, leading to a narrower net loss of $7.203 million versus $13.866 million in 2025. Cash and cash equivalents increased to $56.129 million at March 31, 2026, compared with $40.265 million at year-end 2025, and the company estimates this will fund operations into 2028. Management highlighted continued work with GSK on tebipenem HBr for complicated urinary tract infections and noted an FDA PDUFA decision date of June 18, 2026, which could determine whether tebipenem HBr becomes the first oral carbapenem antibiotic for U.S. cUTI patients.
Spero Therapeutics reported a strong turnaround for 2025, moving from a net loss in 2024 to net income. Total revenues rose to $66.8M for the year ended December 31, 2025, up from $48.0M, driven mainly by collaboration revenue, including from its tebipenem HBr partnership with GSK.
Full-year research and development expense fell to $38.5M from $96.8M, while general and administrative costs declined modestly to $21.2M. Net income attributable to common shareholders was $8.6M for 2025 versus a $68.6M loss in 2024, and fourth quarter diluted EPS reached $0.53.
Cash, cash equivalents and marketable securities were $40.3M as of December 31, 2025, and Spero estimates this will fund operations into 2028. Operationally, the company completed the global phase 3 trial of tebipenem HBr in cUTI, resubmitted its NDA, and highlighted an FDA PDUFA decision date of June 18, 2026.
Spero Therapeutics reported two corporate updates. First, Ankit Mahadevia, MD, resigned from the Board of Directors, its Development Committee, and all officer and director roles at subsidiaries effective January 30, 2026, citing other professional commitments and no disagreements with the company or Board. The company plans to enter into a consulting agreement so he can continue supporting management.
Second, on January 20, 2026, Spero received a letter from the U.S. Securities and Exchange Commission stating the SEC has concluded its investigation and, based on information as of that date, does not intend to recommend an enforcement action against the company. The investigation had been previously disclosed in Spero’s periodic reports.
Spero Therapeutics (SPRO) furnished materials related to its third-quarter update. The company provided a press release announcing results for the quarter ended September 30, 2025 and an investor presentation, both dated November 13, 2025.
The materials are furnished, not filed, which limits their legal exposure under the Exchange Act and Securities Act. The investor presentation is available on the company’s investor relations website.
Spero Therapeutics announced it issued a press release reporting results for the third quarter ended June 30, 2025. The 8-K furnishes that press release as Exhibit 99.1, but the filing itself does not include the underlying financial figures in-line.
The company also furnished an investor presentation as Exhibit 99.2, which management intends to use in investor communications and is available on the company website. Both the press release and presentation are described as "furnished" and are not deemed "filed" for purposes of certain securities-law liabilities.
Spero Therapeutics’ Form 8-K details the voting results of its 12 June 2025 Annual Meeting. A quorum of 40,015,633 shares (71.57%) of the 55.9 million shares outstanding was present.
Board elections: Class II directors Frank E. Thomas, Patrick Vink M.D., and Esther Rajavelu were re-elected through 2028, each receiving roughly 25.7 million votes for and 0.4-2.9 million votes withheld; 13.8 million broker non-votes were recorded.
Auditor ratification: PricewaterhouseCoopers LLP was confirmed as independent auditor for FY 2025 with an overwhelming 39.8 million ‘for’ versus 175 k ‘against’.
Say-on-pay: Executive compensation received shareholder support—25.18 million ‘for’ (96.0%) against 0.64 million ‘against’.
Equity plan amendment: Shareholders approved increasing the 2017 Stock Incentive Plan by 3 million additional shares (22.97 million for / 3.15 million against). This authorizes extra equity that may dilute existing holders once issued but expands flexibility to attract and retain talent.
No financial performance data, earnings guidance, or major strategic transactions were disclosed; the filing is limited to governance and compensation matters.