Influence of time to complete remission and duration of all-trans retinoic acid therapy on the relapse risk in patients with acute promyelocytic leukemia receiving AIDA protocols

Despite the impressive results obtained with standard chemotherapy, approximately 20% of acute promyelocytic leukemia (APL) patients undergo disease relapse thereby requiring salvage therapy. Few data is available on long-term prognosis in relation to time to complete remission (CR): we reviewed 142 patients treated with AIDA protocols and we found that 42 out of 142 (29.6%) patients achieved CR after 35 days (median time, 42 days). No significant differences in presenting features, including FAB subtype, type of PML/RARA transcript and relapse risk at presentation between the two patient groups achieving CR > or <35 days were revealed, except for male sex and older age that were significantly associated with delayed CR. Rate of relapse was 31% in patients with delayed CR compared to 17% in the group of patients who achieved CR<35 days (p=0.001), with a 5-year CIR of 29.6% compared to 12% (p=0.03). APL patients with delayed CR should be more closely monitored during follow-up for early identification of relapse and prompt administration of pre-emptive salvage therapy.