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magenta THERAPEUTICS Exhibit 99.1 Magenta Therapeutics Reports Third Quarter Financial Results and Program Highlights ― Positive topline clinical data from all patients in an investigator - initiated Phase 2 clinical trial evaluating stem cell mobilization and transplant engraftment using MGTA - 145 plus plerixafor in patients with multiple myeloma will be presented as a poster at the 2021 American Society of Hematology ( ASH ) Annual Meeting on December 13 , 2021 - - MGTA - 117 targeted conditioning program clinical trial start - up activities are ongoing after clearance of Investigational New Drug ( IND ) Application ; Phase 1/2 trial expected to open in December 2021 — ― Ended Q3 2021 with approximately $ 192.6 million in cash , cash equivalents and marketable securities , and the company maintains guidance that cash reserves are expected to fund the operating plan into Q3 2023 - Cambridge , MA – November 4 , 2021 – Magenta Therapeutics , Inc. ( Nasdaq : MGTA ) , a clinical - stage biotechnology company developing novel medicines designed to bring the curative power of stem cell transplants to more patients , today reported financial results for the third quarter ended September 30 , 2021 , and recent program highlights . " We are pleased with our recent execution across the portfolio as we look to continue to allocate our capital efficiently to our value - creating opportunities , " said Jason Gardner , D.Phil . , President and Chief Executive Officer , Magenta Therapeutics . " In mid - September , we cleared the IND process for the MGTA - 117 targeted conditioning program and are now conducting the clinical trial start - up activities with the continued expectation of opening the trial this year . The MGTA - 145 stem cell mobilization program also continues to advance with a fully enrolled investigator - initiated trial in multiple myeloma patients , a Phase 2 clinical trial in allogeneic transplant and the expected start of a Phase 2 clinical trial evaluating mobilization and collection of stem cells from patients with sickle cell disease . "