Arsenic trioxide (As2O3) improves survival of patients with acute promyelocytic leukemia (APL) when delivered immediately after induction therapy, according to a new study from researchers with Cancer and Leukemia Group B (Blood. November 11, 2010. Epub ahead of print).
Although arsenic is used as an effective treatment for patients with relapsed APL, this is the first study to confirm its benefit as consolidation treatment for patients in first remission. Powell and colleagues randomized 481 patients to an induction regimen of tretinoin/cytarabine/daunorubicin, followed by two courses of the consolidation regimen of tretinoin/daunorubicin, or to the same induction and consolidation regimen plus two 25-day courses of As2O3 consolidation immediately after induction. After consolidation, patients were randomly assigned to 1 year of maintenance therapy with either tretinoin alone or in combination with methotrexate and mercaptopurine.
“For this study, we used arsenic as an early ‘consolidation therapy’ after the initial standard treatment to essentially, as one of our first patients described, ‘seal the deal’ the first time around. Not only did the leukemia rarely return in the patients who received the arsenic, those patients also lived longer,” said Bayard L. Powell, MD, a principal investigator and lead author on the study in the accompanying press release.
Of the 90% of patients on each arm who achieved remission and were eligible to receive their assigned consolidation therapy, event-free survival was significantly better for patients assigned to the As2O3 arm (80% vs 63% at 3 years; P < .0001). Survival was also better in the As2O3 arm (86% vs 81% at 3 years; P = .059), as was disease-free survival (90% vs 70% at 3 years; P <.0001).