Keros Therapeutics’ board of directors has authorised a ‘poison pill defence’— in response to increasing investor interest in “influencing the company’s control”.
The move comes after certain investors – including one individual holding 11.2% of Keros’s outstanding common stock as of 6 April 2025 – expressed a desire to shape the company’s strategic decisions.
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US-based Keros stated that the limited-duration stockholder rights plan is designed to protect the integrity of its ongoing strategic review process, which could include the potential sale of the company.
As a result of the announcement, Keros’s shares jumped by 13%, reaching $11.67 per share at market open. The company confirmed it has initiated a process to evaluate strategic alternatives and plans to provide updates on the process within 60 days of the 10 April announcement.
This update follows a series of challenges faced by Keros related to its cibotercept clinical programme for pulmonary arterial hypertension (PAH). In December 2024, Keros halted higher-dose cohorts from the Phase II TROPOS study (NCT05975905) after a safety review revealed concerning adverse events, including fluid buildup around the heart – a development that saw the company’s shares plunge by more than 77%.
Keros suspended the two higher-dose groups and eventually ended the study in January 2025, citing “the ongoing safety review due to new observations of pericardial effusion adverse events”.
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By GlobalDataThe candidate was positioned as a rival to MSD’s PAH drug Winrevair (sotatercept). The US Food and Drug Administration (FDA) approved Winrevair in March 2024 and it is projected to reach blockbuster status, generating up to $6.4bn in global sales by 2030, as per GlobalData, the parent company of Pharmaceutical Technology.
Keros’s lead candidate is a TGF-beta inhibitor dubbed elritercept. The candidate is being investigated in the ongoing Phase III RENEW study (NCT06499285), targeting transfusion-dependent anaemia in very low, low or intermediate-risk myelodysplastic syndrome (MDS) patients.
In December 2024, Takeda inked a deal worth up to $1.3bn with Keros to further develop, manufacture and commercialise elritercept worldwide outside of mainland China, Hong Kong and Macau. According to GlobalData’s Pharma Intelligence Center, elritercept is projected to generate up to $425m in 2030, if approved.
Keros is also advancing its pipeline with KER-065, a candidate for Duchenne muscular dystrophy (DMD), which has shown positive early-stage results. The company announced in March 2025 that KER-065 was well tolerated in Phase I trials, with evidence of activin inhibition across “tissues of interest”. Following this announcement, Keros said it plans to engage with regulatory authorities in Q3 2025, with a Phase II trial for DMD expected to begin in Q1 2026, pending regulatory feedback.
