1:Hospital Universitario Fundación Jiménez Díaz, MAdrid, Spain; 2:Center for Definitive and Curative Medicine, Stanford University, Stanford, CA, USA; 3:Div. of Pediatric Hematology/Oncology/Stem Cell Transplant and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA; 4:Stanford Children's Hospital, Palo Alto, CA, USA; 5:Unidad de Innovación Biomédica, Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas, Madrid, Spain; 6:Centro de Investigación Biomédica en Red de Enfermedades Raras, Madrid, Spain; 7:Unidad Mixta de Terapias Avanzadas, Instituto de Investigación Sanitaria Fundación Jiménez Díaz, Madrid, Spain; 8:Hematología y Hemoterapia, Fundación para la investigación Biomédica HIUNJ, Hospital Infantil Universitario Niño Jesús, Madrid, Spain; 9:Rocket Pharmaceuticals, Inc., Cranbury, NJ, USA

Pyruvate kinase deficiency (PKD) is a rare inherited hemolytic anemia caused by mutations in the PKLR gene resulting in decreased red cell pyruvate kinase activity and impaired erythrocyte metabolism. Manifestations include anemia, reticulocytosis, splenomegaly and iron overload, and may be life-threatening. Current treatments are palliative with significant side effects. Preclinical studies in a clinically relevant PKD murine model demonstrated that infusion of gene-modified bone marrow (BM) cells may ameliorate PKD phenotype. Based on these preclinical data, a global Phase 1 clinical trial RP-L301-0119 (NCT04105166) is underway to evaluate the feasibility and safety of lentiviral mediated gene therapy. Six patients with severe PKD (defined as severe and/or transfusion-dependent anemia despite prior splenectomy) will be enrolled. Peripheral blood (PB) hematopoietic stem cells (HSCs) are transduced with PGK-coRPK-WPRE lentiviral vector (LV) and cryopreserved. Following release testing of the investigational product (RP-L301), patients receive myeloablative conditioning. RP-L301 is then thawed and infused. Patients are followed for safety assessments and efficacy parameters including PB and BM genetic correction and clinically significant improvement in anemia.

So far, two adult patients have been treated. Despite baseline hemoglobin (Hb) levels in the 7.0-7.5 g/dL range and substantial prior transfusion burden, both patients displayed normal-range hemoglobin (Hb), improved hemolysis markers, and have required no red blood cell transfusions post-engraftment. PB mononuclear cell VCNs for both patients were >2.0. No RP-L301 related serious adverse events have been observed after 18 months follow-up. In conclusion, , lentiviral gene therapy has shown to be  safe and efficacious for the treatment of PKD.