Long-term outcome of relapsed acute promyelocytic leukemia treated with oral arsenic trioxide-based reinduction and maintenance regimens: A 15-year prospective study.

<bold>Background: </bold>For patients who have acute promyelocytic leukemia (APL) in second complete remission (CR2), optimal postremission strategies remain undefined.<bold>Methods: </bold>The role of an oral arsenic trioxide (As2 O3 )-based regimen in the management of patients who had APL in CR2 was examined.<bold>Results: </bold>Seventy-three patients with APL in first relapse (R1) were studied. Oral As2 O3 -based reinduction resulted uniformly in CR2, irrespective of previous As2 O3 exposure. All patients received oral As2 O3 -based maintenance in CR2. At a median follow-up of 94 months (range, 9-205 months), 43 patients (58.9%) were still in CR2, and 49 (67.1%) had finished the planned 2-year CR2 maintenance with all-trans retinoic acid, oral As2 O3 , and ascorbic acid. Reinduction and maintenance treatments were well tolerated. Grade 1 and 2 headache occurred in 20 patients (27.4%). Hepatotoxicity, all in the form of transaminitis, occurred in 35 patients (47.9%; grade 1 and 2, n = 26; grade 3 and 4, n = 9). Three patients had self-limiting QTc prolongation. The 10-year leukemia-free survival rate was 56.8%. Thirty patients developed R2. Oral As2 O3 -based reinduction led to CR3 in 27 patients (90%). Post-CR3 strategies included autologous hematopoietic stem cell transplantation and oral As2 O3 maintenance. At a post-CR3 follow-up of 30 months (range, 3-166 months), 11 patients were still in CR3. The 5-year and 10-year overall survival rates in the R1 cohort were 79.5% and 67.3%, respectively. Prior receipt of oral As2 O3 maintenance in CR1 was the only risk factor for inferior leukemia-free survival. Central nervous system involvement occurred in 15 patients, including 5 who remained alive. Relapse during oral As2 O3 therapy was the only significant risk factor for central nervous system involvement.<bold>Conclusions: </bold>For patients with relapsed APL, As2 O3 remained effective despite repeated As2 O3 exposures. Oral As2 O3 maintenance was an effective postremission strategy for CR2. Cancer 2018;124:2316-26. © 2018 American Cancer Society. [ABSTRACT FROM AUTHOR]