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Rare disease pyruvate kinase deficiency received first approved disease-modifying therapy.
The US Food and Drug Administration has announced the approval of mitapivat (Pyrukynd) tablets as treatment for hemolytic anemia in adults with pyruvate kinase (PK) deficiency. The oral PK activator, developed by Agios Pharmaceuticals, is the first approved disease-modifying therapy for this disease.
The approval was based on data from ACTIVATE and ACTIVATE-T Phase 3 Studies and supported treatment regardless of transfusion status.
Pyruvate kinase deficiency is a rare disease, occurring in approximately 3-9 cases per 1 million people. The inherited disorder causes premature red blood cell destruction which leads to anemia.
Symptoms often experienced by patients with PK deficiency include fatigue, unusually pale skin, jaundice, shortness of breath, and a fast heart rate. Additionally, patients can develop more severe symptoms such as an enlarged spleen, a surplus of iron in the blood from repeated blood transfusions, and gallstones.
The effectiveness of the drug was evaluated in 2 studies. The randomized, double-blind, placebo-controlled clinical study included 80 adults with pyruvate kinase deficiency who didn't receive blood transfusions. The single-arm study examined 27 adults with PK deficiency who did receive regular blood transfusions.
Patients in both studies were treated with up to 50 mg of mitapivat orally twice a day following an initial dose adjustment period. In the randomized study, patients received the treatment for an average of 24 weeks and for about 40 weeks in the single-arm study.
The effectiveness of mitapivat in the randomized study was determined by a hemoglobin response. By the end of the study, a hemoglobin response was observed in 40% of the patients who received mitapivat compared with no patients in the placebo group.
The single-arm study evaluated the efficacy and safety of mitapivat by utilizing a dose escalation period for up to 16 weeks and eventually following with a fixed dose period for an additional 24 weeks.
A reduction in transfusion burden, defined as a reduction of at least 33% of red blood cell units transfused during the last 24 weeks of treatment. This was compared to the historical transfusion burden on the individual patient, as standardized to 24 weeks.
Of the patients who received mitapivat, 33% met the goal reduction in transfusion burden. This included 22% of patients who didn't require tranfusions during the final 24 weeks of treatment.