1.
Mitapivat improves ineffective erythropoiesis and iron overload in adult patients with pyruvate kinase deficiency
van Beers, E. J., Al-Samkari, H., Grace, R. F., Barcellini, W., Glenthøj, A., DiBacco, M., Wind-Rotolo, M., Xu, R., Beynon, V., Patel, P., et al
Blood advances. 2024
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Editor's Choice
Abstract
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 [W] 96; mitapivat-to-mitapivat [M/M] arm) or switched from placebo (baseline to W24) to mitapivat (W24 to 96; placebo-to-mitapivat [P/M] arm). 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 (n=40) from baseline to W24, sustained to W96. No improvements were observed in the P/M arm (n=40) 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 (LIC) by magnetic resonance imaging (MRI) 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). Mitapivat is the first disease-modifying pharmacotherapy shown to have beneficial effects on iron overload and ineffective erythropoiesis in patients with PK deficiency.
PICO Summary
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).
2.
Red cell transfusion thresholds in outpatients with myelodysplastic syndromes: Combined results from two randomized controlled feasibility studies
Buckstein, R., Callum, J., Prica, A., Bowen, D., Wells, R. A., Leber, B., Heddle, N., Chodirker, L., Cheung, M., Mozessohn, L., et al
American journal of hematology. 2023
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Editor's Choice
PICO Summary
Population
Red blood cell, transfusion dependent patients with myelodysplastic syndromes enrolled in two feasibility trials: REDDS in United Kingdom, Australia and New Zealand, and RBC-Enhance in Canada (n= 66).
Intervention
Liberal transfusion strategy (maintain Hb 110-125 g/L), (n= 33).
Comparison
Restrictive transfusion strategy (maintain Hb 85-100 g/L), (n= 33).
Outcome
The transfusion strategy was applied for 12 weeks. In total, 232 and 471 units of red blood cells were transfused in the restrictive and liberal arms, respectively. Patients in the liberal arm had more complete blood count tests (13.8 vs. 10.3), a mean of 3.1 ± 2.9 more transfusion visits, and a mean of 6.3 ± 5.9 extra units of blood. Overall, the authors of this combined analysis of two feasibility trials, observed less variability in Hb levels in the liberal arm with patients reporting clinically important improvements pre- and post-transfusion (compared with baseline) in selected symptom and functional domains. However, many patients in both transfusion arms experienced stability or declines in their scores.