The role of posttransplantation maintenance chemotherapy in improving the outcome of autotransplantation in adult acute lymphoblastic leukemia

Extending the principle of conventional acute lymphoblastic leukemia (ALL) therapy to transplantation, 77 adult patients receiving autografts in first remission after melphalan with or without total body irradiation were scheduled to receive 6-mercaptopurine (6MP), methotrexate (MTX), and vincristine-prednisone (VP) for 2 years after transplantation to reduce relapse. Seventy-one percent of patients received 6MP, 57% received MTX, and 38% received VP. Thirty patients had a relapse at 1.5 to 80 months (median, 12.5 months), 15 in the first year and 7 beyond 3 years. The cumulative incidence of relapse at 10 years was 42% (95% CI, 31%-55%). The 10-year probabilities of disease-free survival (DFS) and overall (OS) survival were 50% (95% CI, 38%-62%) and 53% (95% CI, 41%-65%), respectively. Age older than 30 years, more than 4 weeks to attain remission, and high-risk karyo-types, for example, t(9;22) or t(4;11), were adverse features contributing to the identification of 3 prognostic risk groups with 0, 1, and 2 adverse features, respectively: standard (47%), intermediate (36%), and high (17%). The 10-year cumulative incidences of relapse (20%, 48%, 85%; P < .0001) and probabilities of DFS (72%, 41%, 10%; P= .0003) were significantly different among these groups. In Cox analysis of the 71 patients alive and well 120 days after transplantation, those receiving 2 or 3 maintenance chemotherapy agents had significantly lower relapse rates and superior DFS compared with those receiving 0 or 1 agent. Our data suggest that maintenance chemotherapy improves the outcome of patients with ALL undergoing autografting. However, it is unlikely that autograft-based strategies are optimal for the high-risk group of patients who should be considered for alternative-donor allograft procedures.