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magenta THERAPEUTICS Exhibit 99.1 Magenta Therapeutics Reports Second Quarter Financial Results and Recent Program Highlights - Progress in addressing the FDA's recommendations regarding bioassay and dose escalations to clear the current clinical hold on the company's Investigational New Drug Application to initiate MGTA - 117 Phase 1/2 clinical trial - - Enrollment complete for Phase 2 clinical trial evaluating MGTA - 145 plus plerixafor in patients with multiple myeloma ; final clinical data expected in Q4 2021 - - Plans to initiate Phase 2 clinical trial of MGTA - 145 plus plerixafor for mobilization and collection of stem cells in patients with sickle cell disease in Q4 2021 - - Ended Q2 2021 with approximately $ 207.8 million in cash , cash equivalents and marketable securities , and updates guidance that cash reserves are expected to fund the company's operating plan into Q3 2023 - Cambridge , MA - August 5 , 2021 – Magenta Therapeutics , Inc. ( Nasdaq : MGTA ) , a clinical - stage biotechnology company developing novel medicines to bring the curative power of stem cell transplants to more patients , today reported financial results for the second quarter ended June 30 , 2021 , and recent program highlights . " The Magenta team has been hard at work prioritizing the advancement of our program portfolio , now with multiple clinical trials underway , including the two Phase 2 clinical trials of MGTA - 145 . We plan to initiate a Phase 1/2 trial of MGTA - 117 in patients with Acute Myeloid Leukemia ( AML ) and Myelodysplastic Syndromes ( MDS ) , assuming we are successful in resolving the clinical hold on our Investigational New Drug ( IND ) Application , and we also plan to initiate a Phase 2 clinical trial of MGTA - 145 plus plerixafor for mobilization and collection of stem cells in patients with sickle cell disease , " said Jason Gardner , D.Phil . , President and Chief Executive Officer , Magenta Therapeutics . " We remain laser - focused on developing transformative mobilization and conditioning treatments for the many patients who stand to benefit . "