Magenta inks deal with Heidelberg to add new ADCs to its transplant palette

The two companies will combine Magenta’s stem cell expertise with Heidelberg’s ATAC platform to develop ADCs loaded with a toxin (amanitin) against four undisclosed cellular targets. (rawpixel via Unsplash)

Magenta Therapeutics’ mission to expand the use of bone marrow transplant therapy has a new ally, with German biotech Heidelberg Pharma joining the cause.

The Cambridge, Massachusetts, biotech says it will work with Heidelberg to develop antibody-drug conjugates (ADCs) that could be used to prepare patients to receive hematopoietic stem cell transplants (HSCT) without exposing them to the highly toxic chemotherapy-based conditioning regimens used at the moment.

Conditioning is the removal of a patient's own stem cells to make way for the new ones delivered via HSCT, and Magenta wants to see if deleting specific cell populations can do the job without taking out the entire bone marrow—which can be life-threatening.

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Magenta—which was one of our 2017 Fierce15 companies—is already working on conditioning ADCs, reporting preclinical data on its lead C-KIT/CD117-depleting agent last year. But the new agreement with Heidelberg expands its position in the category.

Specifically, the two companies will combine Magenta’s stem cell expertise with Heidelberg’s ATAC platform to develop ADCs loaded with a toxin (amanitin) against four undisclosed cellular targets. Magenta has an option to license global development and commercialization rights to each of the product candidates.

If it does so—and all reach the market and meet sales targets—Heidelberg could be in line for $334 million in milestone payments.

“There is a significant need for targeted conditioning regimens for bone marrow transplant, and this is a key area of focus for Magenta,” said Magenta’s chief scientific officer Michael Cooke.

“Amanitin is one of the promising toxins we are exploring in our targeted conditioning programs, and our partnership with Heidelberg … will allow us to fully evaluate the potential of this payload.”

Magenta also has programs focused on expanding stem cells outside the body and thereby increasing the dose that can be delivered during a transplant, headed by ex-Novartis drug MGTA-456 in early-stage clinical development, as well as mobilizing stem cells from the bone marrow to the blood and handling post-transplant complications.