Pharmacogenetics of 6-mercaptopurine in a black Zimbabwean cohort treated for acute lymphoblastic leukaemia

Background: 6-mercaptopurine usage is associated with myelotoxicity and increased risk in patients carrying metabolism-related genetic variations. This study aimed to determine the frequency of candidate gene polymorphisms and their association with 6-mercaptopurine intolerance. Methods: A total of 41 patients on acute lymphoblastic leukaemia treatment were genotyped for TPMT and NUDT15 (rs116855232) alleles, and their association with dose intensity was analyzed. Results: The defective TPMT*3C allele frequency was 9.8%. The median maintenance dose intensity for TPMT*1/*3C participants was considerably lower (47%) when compared with the TPMT*1/*1 wild-type (77%), although not statistically significant. Conclusion: This is the first pharmacogenetics study carried out in a black Zimbabwean leukemia patient cohort. The high defective TPMT*3C (9.8%) allele frequency points to the potential utility of pharmacogenetics testing for safe usage of 6-mercaptopurine in this population.