APOLLO: ATRA plus ATO meets expectations in high-risk APL

All-trans retinoic acid (ATRA) plus arsenic trioxide (ATO) was superior to ATRA-chemotherapy for event-free survival in participants with high-risk acute promyelocytic leukaemia (APL) in the phase 3 TUD-APOLLO-064 trial.

“ATRA plus ATO is the first-line standard of care for patients with low- or intermediate-risk APL [1],” said Prof. Uwe Platzbecker (Leipzig University Hospital, Germany) [1,2]. “However, in high-risk APL, ATRA plus chemotherapy is still the standard of care and ATRA plus ATO has not yet been assessed” [1].  The phase 3 TUD-APOLLO-064 study (NCT02688140) included 133 participants with newly diagnosed high-risk APL, who were randomised 1:1 to the ATRA plus ATO or the ATRA plus chemotherapy arm. The primary endpoint was event-free survival at 2 years follow-up.

The incidence of relapse at 2 years was significantly higher in the chemotherapy arm than in the ATO arm (14.0% vs 1.6%; P=0.011). In line with that, the 2-year event-free survival rate was higher in the ATO arm than in the chemotherapy arm (88% vs 70%; P=0.02). The overall survival data was not yet mature at 2 years of follow-up but suggested an advantage for participants randomised to ATO (93% vs 87%).

“Haematologic toxicities were more prevalent in the chemotherapy arm than the ATO arm, particularly during the consolidation phase,” evaluated Prof. Platzbecker. Thrombocytopenia and grade 3 or 4 neutropaenia were almost non-existent in the ATO group during consolidation but were seen in up to 56% of the participants on chemotherapy. The occurrence of non-haematologic toxicities did not differ substantially between the 2 study arms.

ATRA plus ATO outperformed ATRA plus chemotherapy in participants with previously untreated high-risk APL in terms of event-free survival. Further analysis is awaited and will reveal whether ATRA plus ATO should be the new standard of care for this high-risk APL population.

1. Platzbecker U, et al. A randomized phase III study to compare arsenic trioxide (ATO) combined to ATRA and idarabucin versus standard ATRA and anthracycline-based chemotherapy (AIDA regimen) for patients with newly diagnosed, high-risk acute promyelocytic leukemia. S102, EHA congress 2024, 13–16 June, Madrid, Spain.
2. Lo-Coco F, et al. N Engl J Med. 2013;369:111–121.

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Posted on 12 August 2024