Fulcrum Therapeutics scraps sickle-cell drug after FDA cancer-risk warning

Fulcrum Therapeutics was hit hard on June 2 as it abandoned pociredir, its lead sickle-cell drug, after U.S. regulators raised cancer-risk concerns that left the company with no clear path forward. The Boston-area biotech said the blow would force a broader strategic review, including a possible sale or merger, and it planned to cut costs to conserve cash. Shares plunged about 50% in premarket trading as investors absorbed the loss of the company’s most important development asset.

The decision matters far beyond one company’s pipeline. Sickle-cell disease is a painful inherited blood disorder that can cause severe anemia, organ damage and shortened life expectancy, and new treatment options remain limited despite years of drug development. Pociredir had been one of Fulcrum’s most watched programs because it was designed as an oral therapy, a format that could have offered patients a more convenient alternative to existing approaches. Instead, the drug became a reminder of how quickly a promising program can collapse when regulators see a safety signal they are not willing to overlook.

Fulcrum said the Food and Drug Administration’s objections centered on the PRC2 protein complex, a gene-regulation target that has become increasingly important in drug discovery. The company argued that pociredir’s risk profile should be viewed separately because it acts on a different sub-unit than Ipsen’s Tazverik, but regulators were not persuaded. The FDA also pointed to earlier preclinical malignancy signals tied to pociredir, reinforcing its view that drugs aimed at this biology may carry a class-wide cancer risk rather than a problem isolated to one molecule.

That interpretation is what made the setback so severe. Analysts viewed the agency’s stance as effectively treating the PRC2 complex as a class risk, which would make approval for pociredir highly unlikely even if the drug continued to show biologic activity. Fulcrum said no new safety problems had emerged in clinical trials and noted that the drug had increased fetal hemoglobin, a change that can help reduce disease severity. But the regulator’s concerns outweighed those signals, wiping out the company’s lead sickle-cell program and another potential treatment path for patients hoping for more options in a disease area still marked by deep unmet need.