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

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 center dot 6 (24 center dot 3-85 center dot 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 center dot 5% at the end of induction therapy was associated with relapse (P = 0 center dot 031). The 5-year cumulative incidence of relapse, event-free survival and overall survival were 5 center dot 5%, 92 center dot 3% and 96 center dot 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.