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Beam Therapeutics announced that new research highlighting the company's internal efforts to develop improved transplant conditioning regimens for patients with sickle cell disease undergoing hematopoietic stem cell transplantation will be presented today, June 27, 2022, at 4:00 p.m. CEST at the Federation of American Societies for Experimental Biology Genome Engineering Conference by Nicole Gaudelli, Ph.D., director, head of gene editing at Beam. The conference is being held from June 26-30, 2022, in Lisbon, Portugal. New antibody-based conditioning agents have shown promise in targeting CD117, an optimal conditioning target for eliminating HSCs, but such antibodies generally cannot discriminate between host and transplanted cells, and therefore are designed with short half-life or dosed at low concentrations well before transplant. To potentially solve for this and other safety concerns associated with current conditioning regimens, Beam scientists developed ESCAPE, whereby an edit-antibody pair targeting CD117 was designed to enable edited HSCs to function normally but escape the binding of the conditioning antibody. This strategy is intended to allow the conditioning antibody to continue clearing older unedited host cells while selectively allowing new edited cells to proliferate in the body during engraftment. The findings show that in vitro the ESCAPE antibodies bound to wild-type CD117, blocked binding of its ligand and led to depletion of unedited cells, while enriching for edited cells which were generally not bound by the antibody. High levels of editing efficiency were demonstrated with both a single CD117 edit and simultaneous CD117 and BEAM-101 edits. Beam has also developed a CD117 editing strategy with greater than 75% editing efficiency that is also compatible with an edit to correct the sickle mutation and generate HbG-Makassar, Beam's strategy with its BEAM-102 program. Relative to a control, ESCAPE reduced cell viability of unedited cells while maintaining CD117 edited cells in vitro, suggesting utility as a conditioning agent with a selective advantage to edited HSCs post-transplant.