Magenta Therapeutics is losing its chief medical officer and head of R&D John Davis, M.D., with his last day coming July 30.

Davis helped steer the biotechs early path as well as deals with Avrobio and base editing biotech Beam Therapeutics around its lead stem cell conditioning program, MGTA-117, and MGTA-145 as a potentially new first-line standard of care for stem cell mobilization in a broad range of diseases. His departure comes three years after he joined the company from Pfizer, where he led its early R&D.

The biotech was keen to stress in an 8-K SEC filing (but not a press release) that his departure was not related to any disagreements with the Company on any matter relating to its operations, policies, practices or any issues regarding financial disclosures, accounting or legal matters.

It will now look for a new CMO, while Davis will become an adviser to the company.

RELATED: Magenta CSO Cooke jumps to IFM Therapeutics

This isnt the first move within the R&D ranks: Magenta started 2020 by losing its chief scientific officer when Michael Cooke, Ph.D., hopped over to IFM Therapeutics. In the fall, though, it nabbed Lisa Olson, Ph.D., who previously led immunology discovery at AbbVie, as his replacement.

Conditioning is a necessary step for some gene therapies, but one that can cause side effects like nausea, hair loss and mouth sores or make patients more vulnerable to infection. Magentas platform is based on looking to improve on current methods with an antibody-drug conjugate.

MGTA0117 is made up of an anti-CD117 antibody linked to amanitin, a cell-killing toxin. It is designed to target only hematopoietic, or blood-forming, stem cells and progenitor cells.

Animal studies suggest it could clear space in bone marrow for gene-modified stem cells to take root, Magenta said. The company plans to wrap IND-enabling studies for the antibody-drug conjugate this summer.

MGTA-145, meanwhile, just finished off a midstage test earlier this month, hitting its primary endpoint in a small multiple myeloma study.

Davis' replacement will already have a lot of clinical work on their hands.

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Magenta Therapeutics' research lead Davis hits the exit for family reasons - FierceBiotech