Magenta Therapeutics to Present Data from Across Portfolio at American Society of Gene and Cell Therapy (ASGCT) Annual Meeting

“Magenta’s pipeline continues to deliver new results and continues our progress toward our goal of allowing all patients who can benefit to receive curative stem cell gene therapy or transplant. Our ASGCT presentations demonstrate the far-reaching potential of our programs to widen availability of and improve the patient experience with stem cell gene therapy and transplant,” said John Davis Jr., M.D., M.P.H., M.S., Head of Research & Development and Chief Medical Officer, Magenta Therapeutics. “We are particularly encouraged by the new results on our first-line mobilization and conditioning medicines for patients.”

Data from MGTA-145 First-Line Stem Cell Mobilization Program:

Magenta is developing MGTA-145 as the new first-line standard of care for stem cell mobilization in a broad range of diseases, including autoimmune diseases, blood cancers and genetic diseases, such as sickle cell disease. MGTA-145, a CXCR2 agonist, works in combination with plerixafor, a CXCR4 antagonist, to rapidly and robustly mobilize stem cells for collection and transplant.

These data provide further confirmation that MGTA-145, in combination with plerixafor, enables the same-day mobilization of functional hematopoietic stem cells (HSCs) that can be gene-modified and engrafted.

Title: MGTA-145, in Combination with Plerixafor, Rapidly Mobilizes Large Numbers of HSCs in Humans That Can Be Gene Edited with CRISPR/Cas9 and Mediate Superior Engraftment to Standard-of-Care (Abstract #123)
Presenter: Kevin Goncalves, Ph.D., Magenta Therapeutics, Cambridge, Mass.
Date and Time: Tuesday, May 12, 2020 – 3:45-5:30pm

This abstract demonstrates that MGTA-145 plus plerixafor is a rapid, reliable, efficient medicine to obtain high numbers of HSCs that can be gene edited with CRISPR/Cas9 and mediate durable engraftment in preclinical models.

Title: MGTA-145/Plerixafor-Mediated HSC Mobilization and Intravenous Gene Therapy in Mice Allows for Efficient in vivo HSC Transduction and Stable Gene Marking in Peripheral Blood Cells (Abstract #810)
Presenter: Chang Li, Ph.D., Division of Medical Genetics, Department of Medicine, University of Washington
Date and Time: Wednesday, May 13, 2020 – 5:30-6:30pm

This abstract shows, for the first time, that MGTA-145 plus plerixafor can enable robust mobilization of large numbers of stem cells in animals that can be efficiently modified in vivo by gene therapy without transplant.

Data from CD117-ADC Gene Therapy Conditioning Program

Targeted, disease-modifying antibody drug conjugates (ADCs) are designed to precisely and rapidly remove disease-causing cells in the body and enable immune and blood system reset and long-term engraftment, without the need for chemotherapy or radiation. The results to be presented at ASGCT use a tool CD117-ADC molecule to demonstrate the first-ever successful transplant of gene-modified cells in non-human primates without the use of chemotherapy or radiation. Magenta has built on these results to declare its clinical candidate, MGTA-117, for targeted patient preparation for stem cell gene therapy and transplant. Magenta is on track to deliver initial clinical data on MGTA-117 in 2021.

Title: A Single Dose of Fast Half-Life CD117 Antibody Drug Conjugate Enables Hematopoietic Stem Cell-Based Gene Therapy in Nonhuman Primates (Abstract #533)
Presenter: Naoya Uchida, M.D., Ph.D., Cellular and Molecular Therapeutics Branch; National Heart, Lung, and Blood Institute; National Institutes of Health
Date and Time: Wednesday, May 13, 2020 – 3:45-5:30pm

This abstract demonstrates that a single dose of a tool CD117-ADC selectively depleted HSCs in non-human primates while sparing immune cells, which are important for recovery following transplant. A single dose of CD117-ADC in non-human primates enabled successful transplant and long-term engraftment of HSCs modified with a lentiviral vector encoding the β-globin gene, the gene that causes sickle cell disease and β-thalassemia, with none of the side effects associated with busulfan conditioning.

Additional Posters and Presentations

Title: Expansion with E478 Significantly Increases the Rate of CRISPR-Mediated Homology Directed Repair (HDR) and Improves Engraftment of Human Hematopoietic Stem Cells (Abstract #10)
Presenter: Kevin Goncalves, Ph.D., Magenta Therapeutics, Cambridge, Mass.
Date and Time: Tuesday, May 12, 2020 – 10:15am-12:00pm

Title: MGTA-456, A Cell Therapy Utilizing an Aryl Hydrocarbon Receptor Antagonist (AHRa) Culture, Promotes Expansion of CD34+CD90+Cord Blood (CB) Hematopoietic Stem Cells (HSC), Resulting in Rapid Hematopoietic Recovery, Uniform Engraftment and Better HLA Matched Grafts for Larger Recipients (Abstract #120)
Presenter: John Wagner, M.D., Executive Medical Director, Bone Marrow Transplant Program, University of Minnesota, Minneapolis, Minn.
Date and Time: Tuesday, May 12, 2020 – 3:45-5:30pm

Title: High Dose Hematopoietic Stem Cell Therapies, like MGTA-456, Enable Complete Neural, Peripheral and Skeletal Disease Cross-Correction Through Rapid and Robust Engraftment (Abstract #248)
Presenter: Sharon Hyzy, M.S., Magenta Therapeutics, Cambridge, Mass.
Date and Time: Tuesday, May 12, 2020 – 5:30-6:30pm

Title: A Phase 2 Trial of MGTA-456 Cell Therapy Demonstrates Rapid and Durable Long-Term Improvement in Disease-Specific Outcomes in Inherited Metabolic Disease (IMD) Patients (Abstract #1302)
Presenter: John Wagner, M.D., Executive Medical Director, Bone Marrow Transplant Program, University of Minnesota, Minneapolis, Minn.
Date and Time: Friday, May 15, 2020 – 8:00-9:45am

About Magenta Therapeutics
Magenta Therapeutics is a clinical-stage biotechnology company developing medicines to bring the curative power of immune system reset through stem cell transplant to more patients with autoimmune diseases, genetic diseases and blood cancers. Magenta is combining leadership in stem cell biology and biotherapeutics development with clinical and regulatory expertise, a unique business model and broad networks in the stem cell transplant world to revolutionize immune reset for more patients

Magenta is based in Cambridge, Mass. For more information, please visit www.magentatx.com.

Follow Magenta on Twitter: @magentatx.

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