Beam presents new NHP data demonstrating proof-of-concept for ESCAPE

Beam Therapeutics (BEAM) announced new data for its Engineered Stem Cell Antibody Evasion, or ESCAPE, conditioning platform. Presented in an oral session at the 66th American Society of Hematology Annual Meeting and Exposition in San Diego, the data demonstrated that conditioning and in vivo selection with an anti-CD117 antibody enabled engraftment of base-edited hematopoietic stem cells and induced robust, durable production of fetal hemoglobin in a non-human primate model. ESCAPE is comprised of two investigational drug products: BEAM-103, an anti-CD117 monoclonal antibody that is designed to suppress and/or eliminate hematopoietic stem and progenitor cells that express CD117, and BEAM-104, a cell therapy that includes an edit to the promoter region of the HBG1/2 genes intended to elevate HbF, plus an additional edit to CD117 designed to prevent binding of BEAM-103, allowing the edited cells to function normally and evade targeting by the antibody. Together, this approach aims to provide a non-genotoxic alternative to traditional transplant myeloablative conditioning. The company intends to advance BEAM-103 and BEAM-104 for development in sickle cell disease and beta-thalassemia. Administration of the BEAM-104 edited cells to antibody-conditioned animals led to long-term engraftment. Long term engraftment of HSCs in the marrow was demonstrated by the presence of edited cells in the periphery beyond 6 months. Dosing with the BEAM-103 mAb led to rapid and near complete replacement of wild-type erythroid cells by edited cells, leading to early induction of therapeutically relevant levels of HbF. Levels of cells containing HbF reached greater than 80% post-transplant. All NHPs achieved greater than40% gamma-globin, a key constituent of HbF, post-transplant. Rapid and sustained reactivation of HbF post-transplant showed promise of therapeutic benefit in SCD patients. BEAM-103 dosing was well tolerated with no need for transfusions, antibiotics or additional supportive care. In contrast to busulfan conditioning, NHPs that received BEAM-103 demonstrated only minor decline in neutrophil counts and platelet levels, an expected outcome of the mAb targeting CD117 on wild-type hematopoietic stem and progenitor cells. The CD117 base-edit showed normal receptor function in vitro and in vivo. No changes to CD117 signaling, structure or expression were observed following editing. In NHP studies, normal hematopoietic reconstitution was observed post-transplantation.