FDA grants priority review to Agios’ mitapivat as first oral PK activator for sickle cell disease

Agios Pharmaceuticals (Nasdaq: AGIO) announced that the US FDA has granted Priority Review to its supplemental New Drug Application (sNDA) for mitapivat (Pyrukynd/Aqvesme), an oral pyruvate kinase (PK) activator, for the treatment of sickle cell disease (SCD). The Prescription Drug User Fee Act (PDUFA) goal date is November 1, 2026.

The sNDA was submitted under the FDA’s accelerated approval pathway, meaning a confirmatory trial is required to convert any initial approval to a traditional one. Priority Review shortens the target FDA review timeline from ten months to six months and is granted when a therapy may offer a significant improvement in safety or efficacy for a serious condition. The sNDA was filed following a pre-sNDA meeting in which the FDA recommended submission of a confirmatory trial proposal as a condition of pursuing accelerated approval.

The submission is based on data from the global, randomized, double-blind, placebo-controlled RISE UP Phase III trial in 207 patients aged 16 years and older with SCD, randomized 2:1 to mitapivat 100 mg twice daily or placebo for 52 weeks. As reported at the European Hematology Association 2026 congress, mitapivat demonstrated a statistically significant improvement in the primary endpoint of hemoglobin response — defined as a ≥1.0 g/dL increase from baseline in average hemoglobin from Week 24 through Week 52 — with 40.6% of patients in the mitapivat arm achieving this threshold versus 2.9% on placebo (2-sided p<0.0001). Among hemoglobin responders, mean hemoglobin concentration increased by 1.6 g/dL from baseline. The second co-primary endpoint, annualized rate of sickle cell pain crises, showed a numerical reduction with mitapivat but did not reach statistical significance. New analyses presented at EHA showed a 41.1% relative reduction in the proportion of patients requiring transfusions with mitapivat versus placebo (23.9% vs. 40.6%), and a 55.9% relative reduction in average red blood cell units transfused per patient (0.70 vs. 1.59 units). The safety profile was consistent with prior mitapivat trials, with no treatment-related deaths.

Mitapivat works by activating the pyruvate kinase R enzyme in red blood cells, increasing ATP production and lowering 2,3-diphosphoglycerate (2,3-DPG) levels. Elevated 2,3-DPG promotes the abnormal sickle conformation of hemoglobin, so reducing it decreases hemolysis and red cell sickling.

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The accelerated approval pathway requires a confirmatory trial to be underway at the time of any approval decision. The global REIGNITE Phase III trial (NCT07656415) is designed to assess the clinical benefit of mitapivat on transfusion burden in approximately 159 patients aged 12 years and older with SCD, with the proportion achieving transfusion-free status from Week 4 through Week 52 as the primary endpoint.

Research context

If approved, mitapivat would be the first oral PK activator for SCD and would enter a field where the only previously approved hemoglobin-targeting small molecule, voxelotor (Oxbryta), was voluntarily withdrawn worldwide in September 2024 following a safety imbalance. Novo Nordisk’s etavopivat, another oral PKR activator, met both co-primary endpoints — a 27% reduction in vaso-occlusive crisis rate and a 48.7% hemoglobin response rate versus 7.2% on placebo — in the Phase III HIBISCUS trial, with a regulatory submission planned for the second half of 2026. Cross-trial comparisons between mitapivat and etavopivat are limited by differences in patient populations and endpoints. The gene therapies exagamglogene autotemcel (Casgevy) and lovotibeglogene autotemcel (Lyfgenia), approved in December 2023 and now extended to patients aged 2 years and older, require myeloablative conditioning and remain largely inaccessible to the majority of patients globally. Mitapivat is already approved in the US for PK deficiency (2022) and thalassemia (2025), and Agios has also recently in-licensed cevidoplenib, a SYK inhibitor for immune thrombocytopenia, broadening its rare hematology portfolio beyond the PK activator franchise.


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