Treatment with tremtelectogene empogeditemcel (trem-cel), a CRISPR/Cas9 genetically modified hematopoietic stem cell therapy that does not contain CD33, showed promising results in an early-phase study of patients with acute myeloid leukemia and myelodysplastic syndromes. The researchers, led by John F. DiPersio, MD, PhD, of Washington University School of Medicine, published the findings in Nature Medicine.
The phase I/II study was conducted at 15 sites in the United States and Canada. A total of 30 adults with AML or MDS at high risk of relapse received trem-cel as well as maintenance gemtuzumab ozogamicin, a CD33-targeting antibody, post-transplant.
All patients achieved engraftment by day 28, with timeframes that were “comparable” to standard transplants.
The median survival was 14 months. Adverse events were similar to standard transplants, including anemia, low platelet count, fever, infection, and graft-versus-host disease. Seven patients died during the study, four related to disease progression and three due to transplant-related causes.
“The results of the study lay the groundwork for developing paired CD33-deleted stem cell transplant and CD33-targeted immunotherapy interventions that avoid destruction of healthy donor cells in the course of cancer treatment,” according to the researchers.
The study was supported by Vor Biopharma.
Reference
DiPersio JF, Koehne G, Shah NN, et al. CRISPR−Cas9 CD33-deleted allogeneic hematopoietic cell transplantation with gemtuzumab ozogamicin maintenance in AML: a phase 1/2 trial. Nat Med. 2026. Epub ahead of print. doi:10.1038/s41591-026-04362-1
