The FDA Just Killed a Sickle Cell Drug — in Biotech's Hottest Market

This is where the story gets painful for Fulcrum. The company argued, reasonably, that EED and EZH2 are different proteins with different biological functions. Blocking one shouldn't automatically carry the same risks as blocking the other. It's like saying that because one player on a basketball team got ejected for fouling, every player on the team should be benched.

The FDA didn't buy it.

On May 28, Fulcrum received feedback from the agency following an end-of-phase meeting. The FDA's position was blunt: any drug targeting the PRC2 complex carries equivalent malignancy risk, regardless of which specific subunit it hits. The agency pointed to both the Tazverik cancer data and pociredir's own preclinical malignancy signals (findings from animal studies that had been previously disclosed).

The verdict? Pociredir's benefit-risk profile in sickle cell disease was unacceptable. No regulatory path forward. Game over.

What This Means for Fulcrum

The math here is brutal. Pociredir was Fulcrum's only clinical-stage program. The company's other major asset, losmapimod for a rare muscular dystrophy called FSHD, had already been discontinued in 2024 after failing a Phase 3 trial.

That leaves Fulcrum with some preclinical discovery programs, zero drugs in human testing, and roughly $333 million in cash as of March 31, 2026. Before the crash, shares closed at $6.42; after hours, they were trading around $3.16 to $3.21.

Analysts had been modeling Fulcrum's value almost entirely on pociredir. Some had price targets north of $18. Those models are now worthless. The company is exploring a sale, merger, or some other strategic transaction. Translation: Fulcrum is a pile of cash looking for a purpose.

The Bigger Lesson: Unmet Need ≠ Regulatory Free Pass

This is the part that should make every sickle cell developer pay attention. The FDA has been remarkably flexible in SCD. It approved Casgevy (the first-ever CRISPR therapy) and Lyfgenia (a lentiviral gene therapy) in 2023 based on single-arm trials with just a few dozen patients. It accepted intermediate endpoints like VOC-free periods rather than demanding hard outcomes like mortality data. It even slapped a boxed warning on Lyfgenia for cancer risk and still approved it, requiring lifelong monitoring instead of pulling the plug.

That's real flexibility. But Fulcrum's case shows where the line is.

The difference comes down to benefit magnitude versus risk certainty. Casgevy and Lyfgenia offer something close to a cure: roughly 93% and 88% of patients, respectively, went VOC-free for at least a year. That kind of transformative benefit can justify accepting serious risks, especially with robust monitoring.

Pociredir, as promising as it was, hadn't yet demonstrated that level of clinical benefit in sickle cell patients (it was still in Phase 1b). And when the Tazverik withdrawal made the theoretical cancer risk feel a lot more real, the FDA recalculated the equation. Potential benefit that's still hypothetical can't outweigh a cancer risk the agency now considers a class effect.

Who Should Be Nervous?

Anyone else working on PRC2 inhibitors for non-cancer indications should be rethinking their strategy this week. The FDA's position is sweeping: it's not about EZH2 versus EED versus any other subunit. It's about the entire complex.

But the implications ripple further. The sickle cell pipeline remains one of biotech's most crowded spaces, with next-generation gene editing approaches, novel conditioning regimens, and oral disease-modifying drugs all competing for attention. Approved gene therapies like Casgevy ($2.2 million per patient) and Lyfgenia ($3.1 million per patient) serve only a narrow, highly selected sliver of the roughly 100,000 Americans living with SCD. The need for accessible, oral treatments is enormous.

Pociredir could have been one of those treatments. Instead, it's a cautionary tale.

The Takeaway

The FDA is willing to bend its usual rules for sickle cell disease. It will accept small trials, single-arm designs, and intermediate endpoints. It will approve drugs with boxed cancer warnings if the benefit is curative-level. But it will not let a drug with a class-wide malignancy concern slide through on unmet need alone.

For Fulcrum, that distinction is existential. For the rest of biotech, it's a reminder: the FDA's safety bar doesn't have a "hot market" discount.

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