Arsenic trioxide in comparison with chemotherapy and bone marrow transplantation for the treatment of relapsed acute promyelocytic leukaemia

Background: The best overall treatment strategy for patients with acute promyelocytic leukaemia (APL) in relapse with chemotherapy, bone marrow transplantation (BMT) or arsenic trioxide (As2O3) based therapy remains undefined. Patients and methods: We reviewed the clinical course and treatment outcome of 143 APL cases seen in four major hospitals in Hong Kong over a 10-year period. Results: Complete remission (CR) was attained in 113 cases (79%) with all-trans retinoic acid (ATRA) and chemotherapy. Relapse occurred at a median of 16 months in 54 cases, with a 3-year disease free survival of 56%. Post-relapse treatment was successful in 41 cases (76%), giving an actuarial 3-year overall survival (OS) of 81% from CR1. Three different protocols were used: chemotherapy alone (n = 19), allogeneic BMT (n = 14) and an As2O3-based regimen (n = 21). Chemotherapy was associated with the highest treatment-related mortality (TRM) at 53%, giving a CR2 rate of 47%. TRM was 36% for BMT. The CR2 rate for the As2O3-based regimen was 100%, with no TRM. However, 38% of As2O3 treated patients had subsequent relapses, which were further salvaged in 75% by combined As2O3 plus ATRA. The actuarial OS for the three protocols leveled off by 2 years at 82% for As2O3, 43% for BMT and 23% for chemotherapy (P = 0.0004). Conclusions: our results suggest that As2O3 may be superior to chemotherapy and BMT for the treatment of APL in relapse.