Fulcrum Therapeutics ended development of pociredir, its PRC2 inhibitor for sickle cell disease, after the FDA raised heightened concerns about risks and benefits. The company disclosed at an FDA end-of-phase meeting that emerging data tied to the PRC2 class showed unexpectedly high rates of secondary blood cancers with Ipsen’s previously marketed tazemetostat (Tazverik). Fulcrum said the FDA concluded that PRC2-targeting interventions carry equivalent malignancy risk regardless of which PRC2 subunit is inhibited, and that there was no viable regulatory path forward for pociredir. The biotech discontinued the program and began a comprehensive review of strategic alternatives. The disclosure follows Ipsen’s voluntary withdrawal of Tazverik from the market in March after adverse events emerged in the ongoing Phase Ib/III SYMPHONY-1 trial (NCT04224493). Fulcrum noted that no new safety signals had been observed in pociredir to date. For investors and the field, the decision underscores how class-related safety signals can sharply limit the development runway for epigenetic oncology and hematology targets that share common mechanisms.