Research Jul 4 2025 Researchers at Zhejiang University School of Medicine have identified a single point mutation in the normal PML  gene that can block the effect of arsenic trioxide, a frontline drug for acute promyelocytic leukemia. This discovery uncovers a hidden cause of treatment failure and suggests a new target for genetic screening in relapsed patients. This work addresses the urgent issue of why some patients relapse despite a therapy that otherwise greatly improves survival.