Infants with acute lymphoblastic leukemia and a germline MLL gene are highly curable with use of chemotherapy alone: results from the Japan Infant Leukemia Study Group.

Although infants with acute lymphoblastic leukemia (ALL) and a germline MLL gene have a better prognosis than comparable infants with a rearranged MLL gene, their optimal therapy is controversial. In 2 consecutive studies, conducted between 1996 and 2002, we treated 22 cases of infant ALL with germline MLL using chemotherapy alone. The 5-year event-free survival rate was 95.5% with a 95% confidence interval of 86.9 to 100%. All 21 infants with precursor B-cell ALL have been in first complete remission for 3.5 to 8.8 years. Most treatment-related toxicities were predictable and well tolerated, and neither secondary malignancies nor physical growth impairments have been observed. These results indicate that chemotherapy of the type described here is both safe and highly effective against infant precursor B-cell ALL with MLL in the germline configuration.