All-trans retinoic acid (ATRA) plus arsenic trioxide (ATO) with two initial doses of idarubicin yielded superior event-free survival (EFS) compared with the standard-of-care ATRA plus chemotherapy in patients with high-risk acute promyelocytic leukemia (APL), according to the prospective phase III APOLLO trial.
The first analysis of the study was presented by Uwe Platzbecker, MD, of the University Hospital Leipzig in Germany, at the European Hematology Association 2024 Hybrid Congress in Madrid, Spain. Dr. Platzbecker noted that the study was prematurely discontinued due to slow recruitment during the COVID-19 pandemic and expiration of the reserved study intervention.
The analysis included 68 patients treated with ATRA-ATO and 63 with the standard of care. The median white blood cell count in the entire cohort was 36×109/L (range, 10.1-489.0×109), and 39% of patients had a count over 50×109/L. Disease status was analyzed in 120 evaluable patients.
A total of 93% (n=63) of patients in the ATRA-ATO arm, compared with 91% (n=57) in the ATRA plus chemotherapy arm, achieved complete remission or complete remission with incomplete count recovery.
Early death occurred in five and seven patients in the ATRA-ATO and standard of care arms, respectively, with a recorded cause of bleed in three and four; sepsis in zero and two; thrombosis in one and one; and pulmonary failure due to leukostasis related to APL in one and zero patients, respectively.
After a median follow-up of 31 months (range, 1.7-71.5), the rates of two-year EFS were 89% versus 72% (P=.02), and the rates of two-year overall survival were 93% versus 87% (P=.33) for ATRA-ATO and standard of care, respectively.
“Further analysis of the APOLLO trial may support the implementation of this regimen as the new standard of care in patients with high-risk APL,” Dr. Platzbecker and colleagues suggested.
Reference
Platzbecker U, Adès L, Montesinos P, et al. First results of the APOLLO trial: a randomized phase III study to compare ATO combined with ATRA versus standard AIDA regimen for patients with newly diagnosed, high-risk acute promyelocytic leukemia. Abstract #S102. Presented at the European Hematology Association 2024 Hybrid Congress. June 13-16, 2024; Madrid, Spain.