Evaluation of the efficacy of maintenance therapy for low-to-intermediate-risk acute promyelocytic leukemia in molecular remission: A retrospective single-institution study.

The prognosis of acute promyelocytic leukemia (APL) has become the most favorable among all acute myeloid leukemias, due to the efficacy of treatment with all-trans retinoic acid (ATRA). ATRA combined with anthracycline-based chemotherapy has significantly improved the long-term outcome for low-to-intermediate-risk APL patients; thus, the efficacy of maintenance therapy for patients achieving molecular complete remission (MCR) following consolidation therapy has become debatable. To evaluate the efficacy of maintenance therapy, we conducted a retrospective analysis of 11 consecutive patients with low-to-intermediate-risk APL who received induction and consolidation therapy with ATRA and anthracyclines according to the PETHEMA LPA protocols at our hospital between January, 2001 and March, 2013. All the patients achieved MCR following consolidation therapy. Of these patients, 7 were followed without maintenance therapy, including 2 patients who discontinued maintenance therapy within 2 months. With a median follow-up of 85 months, the overall survival for all the patients was 100%, while the disease-free survival estimate at 5 years with and without maintenance therapy was 100 and 85.7%, respectively; the difference was not statistically significant (P=0.45). Two patients treated with maintenance therapy later developed secondary primary malignancy. Thus, even without maintenance therapy, ATRA combined with anthracyclines exhibited significant efficacy in low-to-intermediate-risk APL patients, suggesting that maintenance therapy, which is associated with adverse events, may be dispensable for patients achieving MCR following adequate consolidation therapy.