Early results from a clinical trial of a drug intended for patients undergoing stem cell transplants showed an ability to mobilize blood cells, but without the toxicity associated with standard-of-care therapy.
Cambridge, Massachusetts-based Magenta Therapeutics said results from its Phase I study of MGTA-145 in healthy volunteers showed that, when combined with Sanofi’s stem cell mobilization drug Mozobil (plerixafor), it was able to safetly mobilize a large quantity of high-quality stem cells in a single day. The stem cells were subsequently shown to successfully engraft in humanized mice. That’s in comparison with the standard of care, granulocyte colony-stimulating factor, or G-CSF, which causes a lot of side effects and requires patients to come into the clinic daily for up to a week.
The data were presented Saturday at the American Society of Hematology’s annual meeting in Orlando, Florida, which wraps up Tuesday. Shares of Magenta were up more than 14% on the Nasdaq Monday when markets opened.
“The current standard of care for stem-cell mobilization, G-CSF, requires five or more days of injections, which is difficult for patients, donors and the healthcare system,” said presenter Dr. John DiPersio, chief of the oncology division at Washington University School of Medicine in St. Louis, in a statement. “The novel mechanism of MGTA-145 may enable single-day dosing, mobilization and collection in all donors and patients, including those with sickle cell disease or autoimmune diseases, and positions it as a promising new first-line standard of care for all transplants as well as gene therapy.”
G-CSF drugs include products like Amgen’s Neupogen (filgrastim) and Neulasta (pegfilgrastim), and biosimilars. Associated side effects include potentially fatal splenic rupture, acute respiratory distress syndrome, capillary leak syndrome and others.
In a subsequent phone interview, DiPersio said the idea is that if MGTA-145 were eventually approved, standard-risk patients with the aforementioned diseases, as well as blood cancers like multiple myeloma and eventually allogeneic stem cell transplant donors, would get MGTA-145 and Mozobil rather than G-CSF. G-CSF would nevertheless continue to have a role in the clinic. “I think G-CSF will still be around for some of these really difficult-to-mobilize patients,” he said.
For now, the data are only in healthy volunteers and animal models rather than patients. However, the data to date did show that five of six patients who received a single dose of MGTA-145 at 0.3mg/kg with Mozobil mobilized more than 20 cells per microliter in a single day, which is considered the threshold for successful mobilization. Whereas about 10% of cells mobilized with G-CSF were positive for the proteins CD34 and CD90 – which is associated with successful engraftment – the same was true of a median 33% of those mobilized with MGTA-145 and Mozobil.
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