• Rachael F Grace, Christian Rose, D Mark Layton, Frédéric Galactéros, Wilma Barcellini, D Holmes Morton, Eduard J van Beers, Hassan Yaish, Yaddanapudi Ravindranath, Kevin H M Kuo, Sujit Sheth, Janet L Kwiatkowski, Ann J Barbier, Susan Bodie, Bruce Silver, Lei Hua, Charles Kung, Peter Hawkins, Marie-Hélène Jouvin, Chris Bowden, and Bertil Glader.
• From the Dana-Farber/Boston Children's Cancer and Blood Disorders Center and Harvard Medical School, Boston (R.F.G.), and Agios Pharmaceuticals, Cambridge (A.J.B., S.B., L.H., C.K., P.H., M.-H.J., C.B.) - all in Massachusetts; Hôpital Saint Vincent de Paul, Lille (C.R.), and Unité des Maladies Génétiques du Globule Rouge, Centre Hospitalier Universitaire Henri Mondor, Créteil (F.G.) - both in France; Hammersmith Hospital, Imperial College Healthcare NHS Trust, London (D.M.L.); Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan (W.B.); Central Pennsylvania Clinic, Belleville (D.H.M.), and Children's Hospital of Philadelphia and Perelman School of Medicine of the University of Pennsylvania, Philadelphia (J.L.K.); Van Creveldkliniek, University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands (E.J.B.); University of Utah, Salt Lake City (H.Y.); Wayne State University School of Medicine, Children's Hospital of Michigan, Detroit (Y.R.); University of Toronto, Toronto (K.H.M.K.); Weill Cornell Medical College, New York (S.S.); Bruce A. Silver Clinical Science and Development, Dunkirk, MD (B.S.); and Stanford University School of Medicine, Palo Alto, CA (B.G.).
• N. Engl. J. Med. 2019 Sep 5; 381 (10): 933-944.

BackgroundPyruvate kinase deficiency is caused by mutations in PKLR and leads to congenital hemolytic anemia. Mitapivat is an oral, small-molecule allosteric activator of pyruvate kinase in red cells.MethodsIn this uncontrolled, phase 2 study, we evaluated the safety and efficacy of mitapivat in 52 adults with pyruvate kinase deficiency who were not receiving red-cell transfusions. The patients were randomly assigned to receive either 50 mg or 300 mg of mitapivat twice daily for a 24-week core period; eligible patients could continue treatment in an ongoing extension phase.ResultsCommon adverse events, including headache and insomnia, occurred at the time of drug initiation and were transient; 92% of the episodes of headache and 47% of the episodes of insomnia resolved within 7 days. The most common serious adverse events, hemolytic anemia and pharyngitis, each occurred in 2 patients (4%). A total of 26 patients (50%) had an increase of more than 1.0 g per deciliter in the hemoglobin level. Among these patients, the mean maximum increase was 3.4 g per deciliter (range, 1.1 to 5.8), and the median time until the first increase of more than 1.0 g per deciliter was 10 days (range, 7 to 187); 20 patients (77%) had an increase of more than 1.0 g per deciliter in the hemoglobin level at more than 50% of visits during the core study period, with improvement in markers of hemolysis. The response was sustained in all 19 patients remaining in the extension phase, with a median follow-up of 29 months (range, 22 to 35). Hemoglobin responses were observed only in patients who had at least one missense PKLR mutation and were associated with the red-cell pyruvate kinase protein level at baseline.ConclusionsThe administration of mitapivat was associated with a rapid increase in the hemoglobin level in 50% of adults with pyruvate kinase deficiency, with a sustained response during a median follow-up of 29 months during the extension phase. Adverse effects were mainly low-grade and transient. (Funded by Agios Pharmaceuticals; ClinicalTrials.gov number, NCT02476916.).Copyright © 2019 Massachusetts Medical Society.

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