After terminating one of 2 late-stage sickle cell disease trials, Pfizer still expects FDA approval in 2026

Though Pfizer has terminated one of two phase 3 trials assessing a monoclonal antibody designed to treat sickle cell disease, the New York-based pharma still plans on securing a market approval for the asset by 2026.

Pfizer had been running a pair of trials under a program known as THRIVE to evaluate inclacumab, a P-selectin inhibitor the pharma acquired after snapping up Global Blood Therapeutics in 2022 for $5.4 billion. In a classic game of biopharma hot potato, GBT had gained the asset from Roche back in 2018.

“Recruitment of one of the two Thrive trials was terminated due to slow recruitment,” a Pfizer spokesperson told Fierce Biotech in an emailed statement.

The page for the study echoes that sentiment, citing “poor accrual and associated recruitment [sic] challenges.” Only 72 of an expected 280 patients were enrolled when the study wrapped on Nov. 24, 2023, according to the federal database.

The THRIVE trials set out to examine the safety and efficacy of inclacumab in reducing vaso-occlusive crisis experienced by patients with sickle cell disease compared to placebo. The terminated program was assessing a single dose of inclacumab, while participants in the remaining trial receive 30 mg/kg of inclacumab every 12 weeks.

The active program bears a primary readout date set for Aug. 15, 2024, according to  

The termination doesn’t impact Pfizer's plans for a potential new drug approval from the FDA in 2026, the company spokesperson said. Inclacumab has received both orphan and rare pediatric disease tags from the federal agency for sickle cell disease.   

The Pfizer trial was shuttered right before the landmark December approval of Vertex Pharmaceuticals’ and CRISPR Therapeutics’ Casgevy in the indication. The gene therapy is a long-awaited treatment for the debilitating and life-threatening condition.

Pfizer still touts a portfolio of three sickle cell assets acquired from GBT, one of which is inclacumab. Oxbryta, which snagged FDA approval in 2019, is another, while the third, a HbS polymerization inhibitor called GBT021601, is in phase 2 development. The study discontinuation won’t impact the midstage program, either, the company spokesperson said.