Researchers at Washington University School of Medicine used CRISPR gene editing to delete the CD33 protein from donor stem cells before transplanting them into patients with high-risk acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). Because AML cells also carry CD33, removing it from healthy donor cells lets doctors hit the cancer with a CD33-targeted drug afterward without wiping out the new blood-forming system.
In the phase 1/2 trial across 15 sites in the US and Canada, all 30 adult patients achieved successful engraftment by day 28, with platelet counts recovering in an average of 16 days. Nineteen patients went on to receive the CD33-targeted maintenance drug gemtuzumab ozogamicin. Average survival in the trial was just over 14 months, with seven deaths recorded (four from cancer progression, three from transplant-related complications).
In a related case, one patient with relapsed high-risk AML who later received a CD33-targeted CAR-T therapy achieved complete remission and has remained cancer-free for more than a year. The team, led by Dr. John F. DiPersio, published the results in Nature Medicine.