Spero Therapeutics SEC filings document the regulatory record of a clinical-stage biopharmaceutical company focused on immunology and inflammation. The filings identify SPRO common stock as listed on the Nasdaq Global Select Market and show the company’s headquarters in Cambridge, Massachusetts.
Quarterly reports on Form 10-Q provide Spero’s financial statements and notes, including disclosures on share-based compensation plans and at-the-market offering activity when applicable. Current reports on Form 8-K have covered operating results, license agreements, FDA approval disclosures for Utebzi, equity plan approvals, charter amendments, shelf registration activity and at-the-market sale agreements.
Spero’s DEF 14A proxy statement is relevant for governance matters submitted to stockholders, including equity plan information and annual meeting voting items. Registration-related filings and prospectus materials are also important because the company has used shelf registration and at-the-market structures to describe potential securities offerings.
Director Cynthia Smith of Spero Therapeutics, Inc. received new equity compensation in the form of restricted stock units and stock options. She was granted 10,000 shares of Common Stock at a price of $0.00 per share, increasing her direct holdings to 85,000 shares. She also received a stock option for 20,000 shares of Common Stock with an exercise price of $2.15 per share, expiring on June 23, 2036.
The 10,000 RSUs will vest on June 23, 2027, provided she continues serving through that date. The 20,000-share option will also vest and become fully exercisable on June 23, 2027 under the same service condition. These awards are compensation-related grants rather than open-market purchases or sales.
Spero Therapeutics director Patrick V.J.J. Vink received new equity awards. He was granted 10,000 restricted stock units, each representing one future common share upon vesting on June 23, 2027, subject to continued service. He was also awarded options on 20,000 shares at an exercise price of $2.15 per share, vesting in full on June 23, 2027 and expiring on June 23, 2036. Following these grants, he directly owns 85,000 common shares.
Spero Therapeutics director Frank E. Thomas received new equity awards as part of his compensation. He was granted 10,000 shares of common stock in the form of restricted stock units, which vest on June 23, 2027, as long as he continues serving through that date.
He was also granted options to buy 20,000 shares of common stock at an exercise price of $2.15 per share. These options vest and become exercisable in full on June 23, 2027, subject to his continued service as a director. After the stock grant, he holds 85,000 common shares directly.
Spero Therapeutics director Scott Thomas Jackson reported new equity awards. He received 10,000 shares of common stock in the form of restricted stock units (RSUs), each representing one share upon vesting. These RSUs vest on June 23, 2027, conditioned on his continued service.
He was also granted stock options for 20,000 shares of common stock at an exercise price of $2.15 per share, expiring on June 23, 2036. These options vest and become exercisable in full on June 23, 2027, subject to continued board service. Following the RSU award, his direct common stock holdings total 85,000 shares. These are compensation-related grants, not open-market purchases or sales.
Spero Therapeutics director John C. Pottage Jr. reported equity awards consisting of both restricted stock units and stock options. He received 10,000 shares of Common Stock as restricted stock units that each convert into one share when they vest on June 23, 2027, subject to his continued service. Following this award, he directly holds 85,000 shares of common stock. He was also granted a stock option for 20,000 shares of common stock with an exercise price of $2.15 per share, expiring on June 23, 2036, which will vest and become exercisable in full on June 23, 2027 if he continues to serve as a director.
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 a smaller quarterly loss as it continued shifting its business toward the tebipenem HBr program partnered with GSK. For the three months ended March 31, 2026, total revenue was $0.3 million, down from $5.9 million a year earlier, mainly due to lower collaboration revenue from GSK as performance obligations were completed.
Research and development expense fell to $2.9 million from $13.6 million, and general and administrative expense declined to $4.9 million, reducing the net loss to $7.2 million, or $0.13 per share. Operating cash flow turned positive, providing $15.9 million, largely from collection of GSK collaboration receivables.
The company ended the quarter with $56.1 million in cash and cash equivalents and stockholders’ equity of $52.9 million. Management expects this cash to fund operations for at least 12 months from the financial statement issuance date but anticipates needing additional capital to develop any future product candidates. Spero’s prospects now largely depend on tebipenem HBr, where a Phase 3 trial met its primary endpoint and GSK’s resubmitted NDA has a PDUFA date of June 18, 2026.
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, Inc. officer Rajavelu Esther reported an automatic sale of common stock tied to tax withholding on vested restricted stock units. On May 4, 2026, 25,240 shares were sold at $2.51 per share to fund a “sell to cover” tax obligation rather than a discretionary trade. After this transaction, Esther directly owned 986,851 shares of Spero Therapeutics common stock.