Thioguanine versus mercaptopurine in childhood ALL.

摘要

Contemporary first-line treatment for childhood acute lymphoblastic leukaemia (ALL) is based on serial multidrug phases over 2-3 years. Appropriate therapy leads to event-free survival rates of about 80%. Phases include induction of remission, consolidation as well as re-induction to prevent emergence of a drug-resistant clone, extracompartment therapy to treat the CNS and testes, and maintenance to eradicate residual leukaemic cells.In today's Lancet, Ajay Vora and colleagues3 report on the UK Medical Research Council's randomised trial ALL97, in which they compared the toxicity and efficacy of 6-thioguanine with 6-mercaptopurine in interim maintenance and maintenance therapy of childhood ALL. The thiopurines 6-mercaptopurine and 6-thioguaninehave played an important part in leukaemia protocols. 6-mercaptopurine is used in ALL whereas 6-thioguanine is mainly used in acute myeloid leukaemia or relapsed ALL First-line treatment for childhood ALL usually includes several cycles of 6-mercaptopurine, starting as early consolidation treatment until up to 36 months after diagnosis. Vora and colleagues challenged this tradition by randomising 1498 children to receive 6-thioguanine or 6-mercaptopurine. After 6 years, event-free survival did not differ between the groups.