Long-term prognosis of childhood acute promyelocytic leukaemia with arsenic trioxide administration in induction and consolidation chemotherapy phases: a single-centre experience

Objectives The efficacy of all‐trans retinoic acid (ATRA) and arsenic trioxide (As2O3) as induction therapy for adult acute promyelocytic leukaemia (APL) has been documented in several clinical trials. However, the role of ATRA/As2O3 combination in induction and consolidation therapy in children remains unclear. Here, we report the efficacy of combined treatment with As2O3 and ATRA as induction and consolidation chemotherapy to treat newly diagnosed childhood APL. Methods From 1998 to 2011, 43 children with newly diagnosed APL received induction and consolidation chemotherapy with ATRA and As2O3 (Protocol B). Rates of complete remission (CR), event‐free survival (EFS), disease‐free survival (DFS), and overall survival (OS) and drug toxicity were compared between children treated with Protocol B and 25 others treated previously with ATRA alone as induction chemotherapy (Protocol A). Results Of 43 patients treated with Protocol B, 41 (95.4%) achieved CR (two died of intracranial haemorrhage on day 10 and 14). In contrast, only 20 (80%) of 25 patients treated with Protocol A achieved CR. Thus, the CR rate was significantly lower in patients receiving induction chemotherapy with Protocol A than in those treated with Protocol B (P = 0.045, χ2 = 6.508). Of the 41 patients who achieved CR on induction therapy with Protocol B, 40 also received consolidation therapy. Molecular relapse, but no overt morphological relapse, occurred in one patient at 25 months after diagnosis; this patient regained CR status with As2O3 treatment. With a median follow‐up period of 75 months, estimated EFS, DFS and OS rates were 92.5 ± 4.2%, 97.1 ± 2.9% and 95.3 ± 3.2%, respectively, for Protocol B. In contrast, with a median follow‐up of 127 months, the EFS, DFS and OS rates at 75 months were 70.4 ± 9.4%, 76.4 ± 9.2% and 70.4 ± 9.4%, respectively, for Protocol A. Thus, patients treated with Protocol A showed significantly lower EFS (P = 0.021) and OS (P = 0.007) rates than those treated with Protocol B. Conclusions Application of As2O3 and ATRA as induction and consolidation chemotherapy resulted in excellent outcomes and improved long‐term prognosis in children with newly diagnosed APL.