Briquilimab Combination is Safe in MDS/AML Undergoing AlloHCT

Lori Muffly, MD, associate professor of medicine at Stanford University in the Division of Blood Marrow Transplant and Cellular Therapy, discusses findings a sub-analysis of a phase 1 study (NCT04429191) investigating briquilimab (formerly known as JSP191) with low-dose total body radiation (TBI) and fludarabine in patients with myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) who are undergoing allogeneic hematopoietic stem cell transplantation (alloHCT).

According to Muffly, this novel combination regimen was safe and well-tolerated for the treatment of patients with MDS and AML undergoing alloHCT.

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0:08 | We were pleased with the fact that the pharmacokinetic data showed consistent and predictable clearance of this antibody to the point where in subsequent studies, we believe that the clearance is so predictable that real time pharmacokinetics would not be needed after dosing this agent.

0:30 | This was a safe combination. There were no significant infusion reactions, there was no briquilimab associated with severe serious adverse events, and no patients experienced graft failure. All patients had full engraftment. In terms of the efficacy, of the 12 AML patients, 9 of them entered transplant with detectable MRD and the MRD was assessed by either flow cytometry, next generation sequencing, or a combination thereof. That's a high-risk population with a median age of 70, 9 out of 12 MRD-positive at time of transplant. At the 1-year follow-up time, 67% of these patients, or 8 of 12, are alive and are MRD-negative. MRD clearance occurred in the 9 who came in positive and occurred in 6 patients with the median time of clearance of 90 days. The overall survival at 1-year was also 67%, so 8 of 12 patients were alive, and half of the patients, so 6 of the 12 were alive at 1 year without the need for ongoing immunosuppression.

1:47 | We were excited about these results. I think they confirmed that this antibody that targets hematopoietic stem cells can be given to older patients with this backbone of flu/TBI. With predictable clearance, it's very safe. There were really no adverse events with the antibody and a 67% relapse-free survival at 1 -year post-transplant. That was quite exciting for us, and the non-relapse mortality was only 8%. Only 1 patient died of transplant-related factors. The MRD clearance occurred in the majority. So, we are excited about these data and about what they say about the future of targeted conditioning in transplant.