CRISPR-edited stem cells shield healthy blood cells during cancer treatment

Researchers genetically modified donor stem cells using CRISPR to remove the CD33 protein, potentially enabling safer, more effective treatments for aggressive blood cancers without destroying healthy transplanted cells. A 30-patient trial showed the edited cells successfully engrafted and withstood a CD33-targeted cancer drug. The phase 1/2 multicenter trial, led by Washington University School of Medicine in St. Louis and published in Nature Medicine, enrolled adults with acute myeloid leukemia or myelodysplastic syndrome. All patients achieved engraftment by day 28, with blood cell recovery times similar to standard transplants. Nineteen patients received the maintenance drug gemtuzumab ozogamicin, maintaining blood counts across doses. The strategy addresses a key limitation of CAR-T therapy, which struggles against these cancers because shared proteins on healthy cells cause collateral damage. Side effects resembled standard transplants, with seven deaths from cancer progression or transplant complications. Researchers hope to combine the edited transplants with CD33-targeted immunotherapies, noting a separate case where a patient achieved remission over a year after CAR-T treatment.