A Phase 3 study evaluating mitapivat for transfusion-dependent alpha- or beta-thalassemia reached primary completion on 2024-04-11, with results showing that 30.4% of participants treated with mitapivat achieved a transfusion reduction response (TRR) compared to 12.6% on placebo. This trial investigated the efficacy and safety of mitapivat in reducing transfusion burden in this patient population.
Background
Mitapivat is being investigated for the treatment of transfusion-dependent alpha- or beta-thalassemia (α- or β-TDT). Thalassemia is a group of inherited blood disorders characterized by reduced or absent hemoglobin synthesis, leading to anemia and often requiring regular blood transfusions.
Trial design
The Phase 3 study (NCT04770779) enrolled 258 participants with transfusion-dependent alpha- or beta-thalassemia. The primary objective was to compare the effect of mitapivat versus placebo on transfusion burden in these participants. Interventions included mitapivat and placebo matching mitapivat.
Key results
The study reported several key outcomes during the double-blind period:
- For the Percentage of Participants Who Achieved Transfusion Reduction Response (TRR), mitapivat showed 30.4% compared to 12.6% for placebo. A Mantel-Haenszel analysis yielded a Common Risk Difference on Response Rate of 17.6% (95.0% CI: 8.0% to 27.2%) with a p-value of 0.0003.
- For TRR2, 13.5% of participants on mitapivat achieved the response versus 2.3% on placebo. The Common Risk Difference on Response Rate was 11.1% (95.0% CI: 5.1% to 17.0%) with a p-value of 0.0003.
- For TRR3, mitapivat demonstrated 14.6% compared to 1.1% for placebo. The Common Risk Difference on Response Rate was 13.4% (95.0% CI: 7.7% to 19.1%) with a p-value of 0.0001.
- For TRR4, 7.6% of participants on mitapivat achieved the response versus 1.1% on placebo. The Common Risk Difference on Response Rate was 6.4% (95.0% CI: 1.9% to 10.9%) with a p-value of 0.0056.
- The Percent Change From Baseline in Transfused RBC Units was a least squares mean of 10.96% (Standard Error: 2.149) for mitapivat, compared to 3.32% (Standard Error: 2.846) for placebo.
- Transfusion-Independence was achieved by 9.9% of participants receiving mitapivat, versus 1.1% for placebo.
What this means
The results from this Phase 3 study indicate that mitapivat significantly reduced transfusion burden in participants with transfusion-dependent alpha- or beta-thalassemia compared to placebo. The consistent positive outcomes across various transfusion reduction response metrics (TRR, TRR2, TRR3, TRR4), along with a notable increase in transfusion independence, suggest a potential clinical benefit for patients requiring regular blood transfusions due to thalassemia. The statistically significant p-values for the primary transfusion reduction endpoints underscore the robustness of these findings, suggesting that mitapivat could offer a new therapeutic option to decrease the need for transfusions in this patient population.
Source
The information regarding these trial results was obtained from ClinicalTrials.gov, a public database of clinical studies. The results for the study NCT04770779, titled "A Study Evaluating the Efficacy and Safety of Mitapivat in Participants With Transfusion-Dependent Alpha- or Beta-Thalassemia (α- or β-TDT)", were posted on 2024-04-11 on clinicaltrials.gov.