Keros Therapeutics drops cibotercept in PAH, cuts about 45% of staff

The trial and the decision

Keros Therapeutics, Inc. (Nasdaq: KROS) said on May 29, 2025 that it would discontinue all development of cibotercept in pulmonary arterial hypertension, or PAH. The company made the decision after analyzing all available safety and efficacy data from TROPOS, a Phase 2 trial of cibotercept, known as KER-012, given with background PAH therapy.

TROPOS was randomized, double-blind and placebo-controlled. Keros had halted the 3.0 mg/kg and 4.5 mg/kg arms on December 12, 2024, after pericardial effusions appeared at those doses. On January 15, 2025, it halted all dosing, including the 1.5 mg/kg and placebo arms, because of new pericardial effusion adverse events. Patients were then followed through their end-of-trial visits.

The release gives no efficacy figures. It says top-line results were shared in a presentation on the investor section of the company's website, and that more detailed findings will go to a future medical meeting. The trial's primary objective was to measure the effect of cibotercept on pulmonary hemodynamics against placebo, with exercise capacity as the key secondary objective. The release does not say how the trial performed on either measure.

Chief executive Jasbir S. Seehra said: "Additional treatment options for individuals with PAH are critically needed." Keros's annual report for 2024 had also listed cardiovascular disorders as a second use for cibotercept. The release says only that the company will evaluate other indications, if any, after its strategic review ends.

The cuts and the savings

Keros will reduce headcount by about 45%, leaving 85 full-time employees. The reduction starts after the 60-day notice period required by the Worker Adjustment and Retraining Notification Act has passed. The company expects average annualized cost savings of about $17 million.

The release says Keros "maintains a robust balance sheet," but it gives no cash balance, and the release does not say how the cuts divide among its programs. The savings figure is the only financial number in the release.

Other programs and the review

The company's most advanced candidate is elritercept, known as KER-050, a ligand trap for anemia and thrombocytopenia in lower-risk myelodysplastic syndromes and in myelofibrosis. Keros licensed it to Takeda Pharmaceuticals U.S.A. in December 2024, and the license became effective January 16, 2025, for all territories outside mainland China, Hong Kong and Macau. Keros's annual report describes a placebo-controlled Phase 3 trial in lower-risk MDS. The second program, KER-065, is being developed for Duchenne muscular dystrophy, with a Phase 1 trial in healthy adult volunteers. The release does not report results from either trial.

The Strategic Committee of the board, made up of independent and disinterested directors, has been reviewing strategic alternatives since April 10, 2025. The options it lists are a sale of the company or another business combination, continued investment in the pipeline, and a return of excess capital to stockholders. The release says the committee has outside financial and legal advisers but does not name them.

Keros says it intends to give a preliminary update on the process no later than June 9, 2025. The release also warns that the review and the workforce reduction could hurt the company's ability to retain key personnel and maintain relationships with partners and suppliers. It lists the company's limited operating history and historical losses among its risks, and says its dependence on KER-065 and elritercept is a risk too.

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