Geron sinks as liver risks plague another imetelstat trial

A week after the FDA put a halt to Geron's ($GERN) in-house studies of the cancer drug imetelstat over toxicity concerns, the agency stepped in on a Mayo Clinic-run trial of the same treatment, citing familiar dangers and imposing a partial clinical hold.

Under the FDA's ruling, patients in the Mayo study must demonstrate that they're getting a clinical benefit from the myelofibrosis-treating imetelstat in order to stay in the trial, Geron said, and the agency wants to see data on the rate and reversibility of liver toxicity before it's willing to fully green-light the study. The partial hold also includes a pause in patient enrollment, but Mayo already ceased signups in January for reasons other than safety, according to Geron.

Now, Mayo investigator Ayalew Tefferi plans to work diligently to satisfy the FDA and get the study back up and running, Geron said, but that may be a cold comfort for the reeling biotech. Last week's full stop on imetelstat sent Geron's shares down about 62% in a day, as worries over the drug's risk of long-term liver damage wiped away optimism tied to some promising efficacy results.

In December, Geron's shares shot up on an early peek at data from the Mayo study, in which imetelstat triggered complete remission in some myelofibrosis patients and charted an overall response rate of 41%. Amid cheers from investors and investigators alike, the company was working through a Phase II program studying the drug in multiple myeloma and thrombocythemia when the FDA clamped a full hold on imetelstat, and now it's stuck in developmental limbo with its sole prospect.

After more than two decades in drug development, Geron has never quite found its way to the finish line, and imetelstat was meant to be the star of the biotech's latest makeover. Geron slowly backed away from its ambitions in stem cells and rebranded itself as a cancer-focused outfit, but repeated failures in HER2-negative breast cancer and non-small cell lung cancer led the company to pare down imetelstat's hoped-for indications, and a Phase II failure for the brain cancer-treating GRN1005 reduced Geron's pipeline to a single candidate.

- read the release

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