Discouraging trial data broadside Catalyst Biosciences

Bad news sent shares in Catalyst Biosciences (Nasdaq: CBIO) cratering on Monday, as the Californian hematology specialist revealed that two patients in the ongoing FIX trial developed a neutralizing antibody after treatment with the Factor IX candidate CB-2679d.

The firm is running the Phase I/II trial through its collaborator ISU Abxis (Kosdaq: 086890) in South Korea. While Catalyst stock dropped 64%, ISU shares lost some 15% of their value.

Catalyst said that the antibodies “do not bind to wildtype FIX,” which meant that both patients could resume treatment with their prescribed intravenous FIX prophylaxis therapies. The patients did not experience any bleeds or other safety issues.