PML‐RARA transcript levels at the end of induction therapy are associated with prognosis in non‐high‐risk acute promyelocytic leukaemia with all‐trans retinoic acid plus arsenic in front‐line therapy: long‐term follow‐up of a single‐centre cohort study

Summary Despite the high cure probability for acute promyelocytic leukaemia (APL), a minority of patients will relapse and the risk factors for relapse are unclear. We retrospectively analysed 212 patients who were diagnosed with non‐high‐risk APL and received all‐trans retinoic acid (ATRA) plus arsenic as front‐line therapy at Peking University Institute of Hematology from February 2014 to December 2018. A total of 176 patients (83%) received oral arsenic (realgar‐indigo naturalis formula) plus ATRA, 36 patients (17%) received arsenic trioxide plus ATRA and 203 patients were evaluable for relapse. After a median (range) follow‐up of 53·6 (24·3–85·4) months, two patients had molecular relapse and eight had haematological relapse. A promyelocytic leukaemia/retinoic acid receptor alpha (PML‐RARA) transcript level of ≥6·5% at the end of induction therapy was associated with relapse (P = 0·031). The 5‐year cumulative incidence of relapse, event‐free survival and overall survival were 5·5%, 92·3% and 96·3% respectively. In conclusion, the present long‐term follow‐up study further confirmed the high cure probability of ATRA plus oral arsenic as front‐line therapy for non‐high‐risk APL and showed that the PML‐RARA transcript level at the end of induction therapy was associated with relapse.