Background
Phase 3, double-blind, randomized (2:1), placebo-controlled, 69 sites in 15 countries. N=207 patients >16y with sickle cell disease, anemia and recurrent pain crises. Mitapivat is an oral allosteric pyruvate kinase activator (↑ATP, ↓2,3-DPG).
Results
Interventions and follow up: Arm A: mitapivat 100 mg BID (n=138)
Arm B: placebo BID (n=69)
Primary endpoints: Hb response (≥1.0 g/dL increase in average Hb wk 24–52) and annualized rate of sickle cell pain crises
mFollow up: NR (52-wk primary assessment; OLE ongoing)
Results: Hb response: 41% (56/138) vs 3% (2/69), adjusted difference 38% (95% CI 29–47), P<.0001
Annualized pain crisis rate: 2.6 vs 3.1, P=.1213 (not met)
Arm B: placebo BID (n=69)
Primary endpoints: Hb response (≥1.0 g/dL increase in average Hb wk 24–52) and annualized rate of sickle cell pain crises
mFollow up: NR (52-wk primary assessment; OLE ongoing)
Results: Hb response: 41% (56/138) vs 3% (2/69), adjusted difference 38% (95% CI 29–47), P<.0001
Annualized pain crisis rate: 2.6 vs 3.1, P=.1213 (not met)
Adverse events
Serious AEs: 20% (28/138) vs 29% (20/69)
Treatment-related SAEs: 1 patient (1%) vs 0
Other AE details: NR
Treatment-related SAEs: 1 patient (1%) vs 0
Other AE details: NR
Conclusions
Mitapivat significantly increased Hb response vs placebo, but did not significantly reduce pain crises, so one of two co-primary endpoints was not met. Supports hemolysis modification but clinical benefit on vaso-occlusion remains unproven.
Key Limitations
Co-primary pain crisis endpoint not met; benefit rests on a laboratory surrogate (Hb). Placebo crisis rate low relative to expectations. Safety data are limited to the abstract; longer-term outcomes (organ damage, quality of life) pending OLE.
Clinical Context
Context: sickle cell therapies (hydroxyurea, L-glutamine, crizanlizumab, gene therapy); voxelotor was withdrawn globally in 2024. Mitapivat is approved for PK deficiency; regulatory status in SCD not stated here and no approval claimed.
