UPDATE 3-Keros halts blood pressure treatment trial on safety issues

Adds analyst comment in paragraph 8, company background in paragraph 11

By Christy Santhosh

Jan 15 (Reuters) - Keros Therapeutics KROS.O said on Wednesday it would voluntarily halt testing of an experimental blood pressure treatment due to safety concerns during a mid-stage trial, causing its shares to hit a record low.

The company was testing its therapy, cibotercept, in patients with pulmonary arterial hypertension (PAH) — a rare disease caused by a constriction of arteries in the lungs, leading to high blood pressure.

Keros said it observed excess fluid build up around the heart in patients and that it was terminating the trial early and would monitor patients who were part of the study.

Last month, the company paused the administration of higher doses of cibotercept after observing the same safety issue in patients. But it was testing a lower dose after a sign-off from an independent data monitoring committee.

Around 1,000 new cases of PAH are diagnosed each year in the U.S., according to government data.

"While we are disappointed in this new development, patient safety is always our top priority," said CEO Jasbir Seehra.

Keros still expects to present clinical data from the trial in the second quarter of 2025.

The safety observations were "possibly specific to certain groups of patients with PAH", Guggenheim analyst Vamil Divan said, adding that it does not reflect negatively on the use of such therapies as a whole for this condition.

The Massachusetts-based company was aiming to compete with Merck's PAH treatment MRK.N Winrevair — approved by the FDA in March 2024. Analysts expect Merck's treatment to become a multi-billion-dollar product for the U.S. drugmaker.

Keros is also developing a treatment for a neuromuscular condition and has an experimental blood cancer drug, elritercept, which is in late-stage development.

The company had cash and cash equivalents of $530.7 million, as of Sept. 30. Shares of Keros were down 17% and set to wipe off $85 million from its market capitalization of $505.5 million, as of last close.

(Reporting by Christy Santhosh in Bengaluru; Editing by Shilpi Majumdar)

((Christy.Santhosh@thomsonreuters.com))