Safety and efficacy of mitapivat in sickle cell disease (RISE UP): results from the phase 2 portion of a global, double-blind, randomised, placebo-controlled trial.

Background: Sickle cell disease, a debilitating, inherited haemolytic anaemia with premature morbidity and mortality, affects millions globally. Mitapivat, a first-in-class, oral, allosteric activator of pyruvate kinase, improves red blood cell survival by increasing ATP and diminishes sickling by decreasing 2,3-diphosphoglycerate. We aimed to evaluate the efficacy and safety of mitapivat in patients with sickle cell disease.

Methods: We report results from the phase 2, 12-week, double-blind period of RISE UP, a global, phase 2/3, double-blind, randomised, placebo-controlled trial. The phase 2 part of the study was conducted at 32 clinical study sites across 13 countries. Patients aged 16 years or older with a confirmed diagnosis of sickle cell disease (any genotype), baseline haemoglobin of 5·5-10·5 g/dL (inclusive), and two to ten sickle cell pain crises within 12 months before providing informed consent, were randomly assigned 1:1:1 to receive oral mitapivat 50 mg, 100 mg, or placebo twice daily, in this portion of the study which is now complete. Randomisation was performed using a permuted-block method and concealed with an interactive response system; patients, investigators, and individuals assessing outcomes were masked to treatment assignment. Primary efficacy and safety endpoints were haemoglobin response (≥1·0 g/dL increase from baseline in average haemoglobin concentration from week 10 through week 12), and type, severity, and relationship to study drug of adverse and serious adverse events. Efficacy and safety endpoints were evaluated in the full analysis set (all randomly assigned patients) and safety analysis set (all patients who received at least one dose of study drug), respectively. This study is registered with ClinicalTrials.gov as part of an ongoing phase 2/3 study (NCT05031780).

Findings: Between Jan 19, 2022, and April 25, 2023, 79 patients were randomly assigned (51 [65%] female, 28 [35%] male; 46 [58%] Black or African American, 26 [33%] White, five [6%] multiracial, two [3%] Asian); 26 received mitapivat 50 mg, 26 received mitapivat 100 mg, and 27 received placebo, twice daily. Both treatment groups showed a statistically significant haemoglobin response rate versus placebo (12 [46%] of 26 patients in the mitapivat 50 mg group and 13 [50%] of 26 patients in the mitapivat 100 mg group, versus one [4%] of 27 patients in the placebo group; two-sided p=0·0003 and p=0·0001, respectively). Mitapivat was generally well tolerated. Serious adverse events were reported in two (8%) of 26 patients in the mitapivat 50 mg group, four (15%) of 26 patients in the mitapivat 100 mg group, and three (11%) of 27 patients in the placebo group; grade 3 or worse adverse events occurred in three (12%), five (19%), and two (7%) patients, respectively. No serious or grade 3 or worse adverse events were considered treatment related and there were no treatment-related deaths. The most common grade 3 or worse adverse events were infections and infestations, and included one patient in the placebo group with an infected skin ulcer, one patient in the mitapivat 50 mg group with meningitis and one with pelvic inflammatory disease, and one patient each with malaria, pneumonia, and tonsillitis in the mitapivat 100 mg group.

Interpretation: Mitapivat, through its dual effect of increasing ATP and decreasing 2,3-diphosphoglycerate, could provide clinical benefit to patients with sickle cell disease. These results support continued evaluation of mitapivat in the phase 3 portion of the study.

Funding: Agios Pharmaceuticals.