Management of relapse in acute promyelocytic leukaemia treated with up‐front arsenic trioxide‐based regimens

Summary The standard of care for patients with acute promyelocytic leukaemia (APL) relapsing after front‐line treatment with arsenic trioxide (ATO)‐based regimens remains to be defined. A total of 67 patients who relapsed after receiving ATO‐based up‐front therapy and were also salvaged using an ATO‐based regimen were evaluated. The median (range) age of patients was 28 (4–54) years. While 63/67 (94%) achieved a second molecular remission (MR) after salvage therapy, three (4·5%) died during salvage therapy. An autologous stem cell transplant (auto‐SCT) was offered to all patients who achieved MR, 35/63 (55·6%) opted for auto‐SCT the rest were administered an ATO + all‐trans retinoic acid maintenance regimen. The mean (SD) 5‐year Kaplan–Meier estimate of overall survival and event‐free survival of those who received auto‐SCT versus those who did not was 90·3 (5·3)% versus 58·6 (10·4)% (P = 0·004), and 87·1 (6·0)% versus 47·7 (10·3)% (P = 0·001) respectively. On multivariate analysis, failure to consolidate MR with an auto‐SCT was associated with a significantly increased risk of relapse [hazard ratio (HR) 4·91, 95% confidence interval (CI) 1·56–15·41; P = 0·006]. MR induction with ATO‐based regimens followed by an auto‐SCT in children and young adults with relapsed APL who were treated with front‐line ATO‐based regimens was associated with excellent long‐term survival.