Magenta Therapeutics announced availability of data presentations across its stem cell mobilization and targeted conditioning programs at the European Society for Blood and Marrow Transplantation (EBMT) 2021 annual meeting, held virtually March 14-17, 2021. Magenta is developing MGTA-145 plus plerixafor to harness these agents’ complementary mechanisms to mobilize hematopoietic stem cells (HSCs) for collection and transplantation, including for use with gene therapies. The ability to provide rapid, reliable, predictable and safe mobilization and collection of HSCs in stem cell transplantation could position MGTA-145 plus plerixafor to be the preferred mobilization regimen across multiple diseases due to improved patient experience and collection outcomes. Data from this Phase 1 clinical trial with healthy volunteers further underscore the potential utility of MGTA-145 plus plerixafor as an effective, single-day mobilization and collection regimen for autologous and allogeneic HSC transplant. MGTA-145 plus plerixafor rapidly mobilized large numbers of HSCs and showed durable engraftment, successful gene-modification and immunosuppressive properties by reducing Graft-versus-Host disease (GvHD) in preclinical models. This abstract is an encore presentation by the Company. Magenta is developing a platform of novel antibody-drug conjugates (ADCs) for conditioning, a step in the transplant process that currently relies on the use of systemic chemotherapy agents and radiation. Magenta’s targeted conditioning programs are designed to selectively eliminate stem cells and/or immune cells from a patient prior to stem cell transplant or gene therapy. The conditioning ADCs have the potential to reduce or eliminate the need for high dose or high intensity chemotherapy-based conditioning regimens. MGTA-117, Magenta’s most advanced conditioning program, is a CD117-targeted antibody conjugated to amanitin and intended for use in patients undergoing transplant or gene therapy. MGTA-117 is designed to deplete hematopoietic stem cells and clear space in the bone marrow prior to transplant to enable long-term engraftment and improved disease outcomes in patients. MGTA-117 has shown high selectivity, potent efficacy and tolerability in multiple preclinical studies. The Company expects to file an Investigational New Drug (IND) application for MGTA-117 in mid-2021, and, upon acceptance of the IND by the U.S. FDA, Magenta plans to initiate a Phase 1/2 clinical trial to evaluate MGTA-117 in patients with acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS), with initial safety and pharmacokinetic data available for internal assessment by Fourth Quarter 2021. These initial data are expected to be directional for the Company’s dose escalation plans.