Treatment outcomes in relapsed acute promyelocytic leukemia patients initially treated with all- trans retinoic acid and arsenic compound-based combined therapies

Contemporary combined therapies that include the use of all-trans retinoic acid (ATRA) and arsenic compounds have reduced relapse rates from ~50 to <10% in acute promyelocytic leukemia (APL) patients, however relapse treatment remains controversial. Treatment outcomes in relapsed patients with APL previously treated with combined ATRA + arsenic compound therapy were investigated. A retrospective, observational study was conducted of 25 patients with APL (male to female ratio, 17:8; mean age, 36.4±10.3 years) exhibiting first-time relapse following combined ATRA + arsenic compound therapy. These patients were subsequently treated with secondary ATRA + arsenic compound therapy, salvage chemotherapy, monoclonal antibody therapy or intrathecal chemotherapy, between January 1994 and December 2010. The overall remission rate, duration of remission and toxic effects were assessed. Patient outcomes included mortality during secondary induction therapy (6/25, 24.0%); complete recovery from central nervous system (CNS) relapse following intrathecal chemotherapy (1/25, 4.0%); complete remission following ATRA + arsenic compound therapy (10/25, 40.0%), chemotherapy (3/25, 12.0%) and targeted therapy (1/25, 4.0%); and non-remission (NR) following ATRA + arsenic compound therapy (4/25, 16%). Four (16.0%) patients were subsequently treated with allogeneic hematopoietic stem cell transplantation (allo-HSCT), two of which remained disease-free at the end of the study period and two of which succumbed to the disease. Secondary bone marrow and CNS relapse occurred in 14 (56.0%) patients and one (4.0%) patient, respectively. ATRA + arsenic compound-based combination therapy was effective in re-inducing morphological remission in relapsed patients with APL with previous exposure to ATRA + arsenic compounds, producing low molecular remission rates and high risk of secondary relapse. Furthermore, investigation of early allo-HSCT is required to determine its potential as a therapeutic option for re-inducing morphological remission in relapsed patients with APL with previous exposure to ATRA + arsenic compounds.