ASH 2021 | Update on Phase II study of MGTA-145 + plerixafor for stem cell mobilization in multiple myeloma
Surbhi Sidana, MD, Mayo Clinic, Stanford, CA, gives an overview of the design and preliminary results of a Phase II study assessing the efficacy of MGTA-145, a novel CXCR2 agonist, in combination with plerixafor in mobilizing hematopoietic stem cells (HSCs) in transplant-eligible patients with multiple myeloma (NCT04552743). The study reported a manageable toxicity profile, with pain being the most common side effect, and 88% of patients met the primary endpoint of collecting two million CD34+ cells/kg. In addition, preliminary data show promising results in terms of engraftment success and durability. Dr Sidana explains that this new stem cell mobilization method offers several advantages in comparison to other existing strategies. This interview took place at the 63rd ASH Annual Meeting and Exposition congress in Atlanta, GA.
Transcript (edited for clarity)
So MGTA-145 is a novel drug. It’s a CXCR2 agonist. And in healthy volunteers, it has shown the potential for rapid stem cell mobilization, especially when combined with plerixafor. So we conducted this study, which is an investigator initiated trial. It’s the first study in cancer patients for stem cell mobilization. And what we did was we gave patients plerixafor in the morning, followed two hours later by MGTA-145 and started stem cell collection in patients with myeloma within 30 minutes...
So MGTA-145 is a novel drug. It’s a CXCR2 agonist. And in healthy volunteers, it has shown the potential for rapid stem cell mobilization, especially when combined with plerixafor. So we conducted this study, which is an investigator initiated trial. It’s the first study in cancer patients for stem cell mobilization. And what we did was we gave patients plerixafor in the morning, followed two hours later by MGTA-145 and started stem cell collection in patients with myeloma within 30 minutes. So this was for transplant eligible patients with myeloma. We accrued a total of 25 patients and patients could then undergo stem cell transplant per usual standard of care guidelines with melphalan based conditioning. What we found was this drug was very well tolerated. Pain was the most common side effect, which was seen in 50% of patients. And in about a third of patients, this was acute onset pain within five minutes of giving the MGTA-145 infusion and all but one patient’s pain resolved without any medication. And overall, it didn’t last more than a few minutes. So very tolerated.
And when we look at stem cell yield, so this is the first time you can give a drug and collect cells on the same day. The other drugs require you to collect cells after a few days of injections. So the median stem cell yield in these 25 patients was 5 million CD34-positive cells per kg. And so the study design was such that patients could come back for a second day of collection if they collected less than 6 million. And so what we found was the first day of collection was obviously higher than the second day for patients who needed to come back for a second day. This is consistent with prior data. 88% of patients met the primary endpoint of collecting enough cells to proceed with stem cell transplant, which is 2 million CD34-positive cells per kg. And really when these patients underwent transplant, so far we have data on 18 patients. All 18 have engrafted. And in 13 patients we have day 100 follow-up, and these patients all have durable engraftment.
So again, this is a new method to collect stem cells, which can save patients’ time. They don’t need to collect and come back for injections over multiple days. It can be easier logistically for centers and is a real advance in stem cell mobilization for patients with myeloma or other cancers as this drug is developed.
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