A case of T-cell acute lymphoblastic leukemia in an NUDT15-variant patient who developed severe myelosuppression caused by 6-mercaptopurine during maintenance therapy

Abstract

We experienced treating a 12-year-old boy who developed severe myelosuppression caused by 6-mercaptopurine (6-MP) during maintenance therapy of T-cell acute lymphoblastic leukemia. We were able to continue his chemotherapy by reducing the 6-MP dose. We suspected a relationship between his severe myelosuppression and the enzymes involved in 6-mercaptopurine metabolism, but his gene alleles that have been reported to be related to 6-MP metabolism, such as TPMT, ITPA, MTHFR, and ABCC4, were of the wild type. However, we detected a heterozygous variant in NUDT15, which was reported to be associated with 6-MP intolerance.