On December 7, 2020 Magenta Therapeutics (NASDAQ: MGTA), a clinical-stage biotechnology company developing novel medicines to bring the curative power of stem cell transplant to more patients, reported final clinical results from its earlier completed Phase 1 clinical trial as well as development updates for its MGTA-145 stem cell mobilization therapy, including commencement of enrollment in a Phase 2 clinical trial in multiple myeloma, and its plans for a Phase 2 clinical trial in allogeneic stem cell transplant for patients with acute myeloid leukemia (AML), acute lymphocytic leukemia (ALL) and myelodysplastic syndrome (MDS). The company also previously announced a clinical collaboration with bluebird bio to evaluate MGTA-145 for mobilizing and collecting stem cells in adults and adolescents with sickle cell disease (SCD). Additional preclinical results were also presented at the 62nd American Society of Hematology (ASH) (Free ASH Whitepaper) Annual Meeting and Exposition, taking place virtually from December 5-8, 2020, on the Magenta conditioning platform, including MGTA-117 program, which is a targeted antibody-drug conjugate (ADC) to prepare patients for stem cell transplant.

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MGTA-145 Advancement to Phase 2 Development in Blood Cancers

The company announced that enrollment has started and is ongoing in a Phase 2 clinical trial of MGTA-145, used in combination with plerixafor, to mobilize and collect stem cells for autologous stem cell transplantation of multiple myeloma patients at Stanford University. Magenta expects that this trial will provide patient-level data on stem cell mobilization and collection, characteristics of the mobilized graft and engraftment in patients with multiple myeloma.

Additionally, through a collaboration with the National Marrow Donor Program/Be The Match, a global leader in facilitating allogeneic hematopoietic stem cell transplantation, Magenta plans to initiate a Phase 2 clinical trial in early 2021 using MGTA-145 to mobilize and collect stem cells from allogeneic donors for transplant in patients with AML, ALL and MDS. Allogeneic stem cell transplant provides a potentially curative therapeutic option for patients with these diseases. This clinical trial will evaluate stem cell mobilization, collection, cell quality, engraftment and the potential for reduced Graft-versus-Host Disease (GvHD), which is of particular importance in the allogeneic transplant setting.

MGTA-145 in Sickle Cell Disease

Magenta Therapeutics recently announced an exclusive clinical collaboration with bluebird bio to evaluate the utility of MGTA-145, in combination with plerixafor, for the mobilization and collection of stem cells in adults and adolescents with SCD.

The data from this clinical trial could provide proof-of-concept for MGTA-145, in combination with plerixafor, as the preferred mobilization regimen for patients with SCD. bluebird bio’s experience with plerixafor as a mobilization agent in SCD aligns with Magenta’s combination therapy approach, utilizing MGTA-145 plus plerixafor with potential for safe, rapid and reliable mobilization of sufficient quantities of high-quality stem cells to improve outcomes associated with stem cell transplantation.

MGTA-145 Presentations at ASH (Free ASH Whitepaper)

Magenta presented final clinical data from its MGTA-145 stem cell mobilization Phase 1 clinical trial in healthy volunteers at the ASH (Free ASH Whitepaper) Annual Meeting. All primary and secondary endpoints were met in the study completed earlier this year.

The results demonstrate that a single dose of MGTA-145, in combination with plerixafor, rapidly and reliably mobilized high numbers of stem cells in a single day without the need for G-CSF for potential use in diseases that can benefit from autologous and/or allogeneic stem cell transplantation. The additional data also offer further confirmation that MGTA-145, in combination with plerixafor, was well tolerated and provides a rapid and reliable method to obtain large numbers of hematopoietic stem cells. Transplant of these cells in preclinical models resulted in enhanced, durable engraftment, in addition to highly immunosuppressive properties, leading to reduced GvHD.

"Results from this study provide a robust dataset and proof of concept that MGTA-145, in combination with plerixafor, provides rapid and robust mobilization of stem cells and that these cells have better engraftment potential, are able to be gene modified and engraft and reduce GvHD in preclinical models compared to cells mobilized with other available agents. The data reinforce the availability of compelling opportunities for development in both the autologous and allogeneic transplant settings," said John Davis Jr., M.D., M.P.H., M.S., Head of Research & Development and Chief Medical Officer, Magenta Therapeutics.

The data were presented by Steven M. Devine, MD, Chief Medical Officer of the National Marrow Donor Program/Be The Match and Associate Scientific Director of the CIBMTR (Center for International Blood and Marrow Transplant Research).

Conditioning Program (MGTA-117 and CD45-ADC) Presentations at ASH (Free ASH Whitepaper)

Magenta also provided updates on its conditioning platform at the ASH (Free ASH Whitepaper) Annual Meeting, including MGTA-117 and CD45-ADC programs. Preclinical data from a study of MGTA-117 demonstrate that it is an effective, potent conditioning agent for transplant with anti-leukemic activity, significantly decreasing tumor burdens, leading to delayed tumor growth and increased median survival rates in animal models of AML. Ongoing GLP toxicology and GMP manufacturing progress continue to be supportive of advancing MGTA-117 towards an IND filing in AML and MDS.

Additionally, preclinical data from a study of Magenta’s CD45-ADC, a CD45-targeted conditioning agent designed to remove the cells that cause autoimmune diseases to enable curative immune reset, demonstrated the ability to achieve successful outcomes as a single agent in the most challenging disease model through fully mismatched allogeneic hematopoietic stem cell transplant, where only radiation or combinations of toxic chemotherapies are available, potentially providing patients the option of a reduced toxicity conditioning regimen. The company continues to evaluate this program preclinically.

About MGTA-145

MGTA-145 is being developed in combination with plerixafor to harness complementary chemokine mechanisms to mobilize hematopoietic stem cells for collection and transplantation. This new combination has the potential to be the preferred mobilization regimen for rapid and reliable mobilization and collection of hematopoietic stem cells to improve outcomes in autologous and allogeneic stem cell transplantation, which can rebuild a healthy immune system for patients with blood cancers, genetic diseases and autoimmune disorders.

MGTA-145 has the potential to replace the current standard of care for patients and allogeneic donors who currently rely on the use of granulocyte-colony stimulating factor (G-CSF) alone or in combination with plerixafor, which can take up to five days or longer to mobilize sufficient numbers of stem cells, often resulting in significant bone pain and other side effects. (Press release, Magenta Therapeutics, DEC 7, 2020, View Source [SID1234572302])