Fulcrum Therapeutics shares plunge after halting sickle-cell drug over FDA safety concerns

Tuesday 02 June 2026 - 10:58

Shares of Fulcrum Therapeutics fell sharply by 50% in premarket trading after the company announced it was discontinuing development of its experimental sickle-cell disease treatment due to safety concerns raised by the U.S. Food and Drug Administration (FDA).

The decision centers on the oral drug pociredir, which was being developed to treat sickle-cell disease, a genetic blood disorder that can cause severe pain, anemia, organ damage, and reduced life expectancy. The FDA reportedly raised concerns about a potential cancer risk linked to the drug’s mechanism of action.

Following these regulatory concerns, the company also stated it would explore strategic alternatives, including a possible sale or merger.

Sickle-cell disease drug development has faced multiple setbacks in recent years. In 2024, Pfizer withdrew its approved treatment Oxbryta and halted related studies due to safety issues, highlighting broader challenges in the field.

Pociredir was designed to increase fetal hemoglobin levels by targeting the PRC2 protein complex, which normally suppresses its production. However, concerns emerged that drugs acting on this pathway could be associated with secondary blood cancers, prompting increased regulatory caution.

The FDA’s feedback also followed broader industry concerns, including the global withdrawal of Ipsen’s cancer therapy Tazverik earlier this year over similar safety risks.

The announcement has raised uncertainty around the future of Fulcrum’s pipeline and reflects growing scrutiny of novel therapies targeting complex genetic pathways.