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  • van Beers EJ
  • Al-Samkari H
  • Grace RF
  • Barcellini W
  • Glenthøj A
  • et al.
Blood Adv. 2024 May 28;8(10):2433-2441 doi: 10.1182/bloodadvances.2023011743.
POPULATION:

Adults with pyruvate kinase deficiency not regularly transfused, enrolled in the phase 3 ACTIVATE clinical trial and long term extension (LTE) (n= 80).

INTERVENTION:

Mitapivat throughout ACTIVATE/LTE baseline to week (W) 96 (mitapivat-to-mitapivat M/M arm, n= 40).

COMPARISON:

Switched from placebo (baseline to W24) to mitapivat W24 to 96 (placebo-to-mitapivat P/M arm, n= 40).

OUTCOME:

Changes from baseline in markers of iron overload and erythropoiesis were assessed to W96. Improvements in hepcidin (mean [95% confidence interval (CI)] 4770.0 ng/L [-1532.3, 11,072.3]), erythroferrone (-9834.9 ng/L [-14,328.4, -5341.3]), soluble transferrin receptor (-56.0 nmol/L [-84.8, -27.2]), and erythropoietin (-32.85 IU/L [-54.65, -11.06]) were observed in the M/M arm from baseline to W24, sustained to W96. No improvements were observed in the P/M arm to W24; however, upon transitioning to mitapivat, improvements similar to the M/M arm were seen. Mean (95% CI) changes from baseline in liver iron concentration by magnetic resonance imaging at W96 were -2.0 mg Fe/g dry weight (dw) (-4.8, -0.8; M/M arm) and -1.8 mg Fe/g dw (-4.4, 0.80; P/M arm).

Pyruvate kinase (PK) deficiency is a rare, hereditary disease characterized by chronic hemolytic anemia. Iron overload is a common complication regardless of age, genotype, or transfusion history. Mitapivat, an oral, allosteric PK activator, improves anemia and hemolysis in adult patients with PK deficiency. Mitapivat's impact on iron overload and ineffective erythropoiesis was evaluated in adults with PK deficiency who were not regularly transfused in the phase 3 ACTIVATE trial and long-term extension (LTE) (#NCT03548220/#NCT03853798). Patients in the LTE received mitapivat throughout ACTIVATE/LTE (baseline to week 96; mitapivat-to-mitapivat [M/M] arm) or switched from placebo (baseline to week 24) to mitapivat (week 24 to week 96; placebo-to-mitapivat [P/M] arm). Changes from baseline in markers of iron overload and erythropoiesis were assessed to week 96. Improvements in hepcidin (mean, 4770.0 ng/L; 95% confidence interval [CI], -1532.3 to 11 072.3), erythroferrone (mean, -9834.9 ng/L; 95% CI, -14 328.4 to -5341.3), soluble transferrin receptor (mean, -56.0 nmol/L; 95% CI, -84.8 to -27.2), and erythropoietin (mean, -32.85 IU/L; 95% CI, -54.65 to -11.06) were observed in the M/M arm (n = 40) from baseline to week 24, sustained to week 96. No improvements were observed in the P/M arm (n = 40) to week 24; however, upon transitioning to mitapivat, improvements similar to those observed in the M/M arm were seen. Mean changes from baseline in liver iron concentration by magnetic resonance imaging at week 96 in the M/M arm and the P/M arm were -2.0 mg Fe/g dry weight (dw; 95% CI, -4.8 to -0.8) and -1.8 mg Fe/g dw (95% CI, -4.4 to 0.80), respectively. Mitapivat is the first disease-modifying pharmacotherapy shown to have beneficial effects on iron overload and ineffective erythropoiesis in patients with PK deficiency. This trial was registered at www.ClinicalTrials.gov as #NCT03548220 (ACTIVATE) and #NCT03853798 (LTE).