Background
Phase III non-inferiority RCT (n=276), newly diagnosed low/intermediate-risk APL (WBC <10K) diagnosed morphologically with genetic confirmation (PML-RARA by RT-PCR or t(15;17) by FISH). PS ≤2, Cr ≤3.0, total bilirubin ≤3.0.
Interventions and follow up
Arm A: ATRA 45 mg/m2/d + arsenic trioxide (ATO) 0.15 mg/kg/d, chemotherapy-free, through induction and consolidation
Arm B: ATRA + chemotherapy (idarubicin-based AIDA protocol with mitoxantrone/idarubicin consolidation and 2-yr maintenance)
Primary endpoint: 2-year EFS (non-inferiority)
Median follow-up: 34.4 mo (primary); 40.6 mo (update)
Arm B: ATRA + chemotherapy (idarubicin-based AIDA protocol with mitoxantrone/idarubicin consolidation and 2-yr maintenance)
Primary endpoint: 2-year EFS (non-inferiority)
Median follow-up: 34.4 mo (primary); 40.6 mo (update)
Results
2-yr EFS: 97% vs 86% (A vs B), non-inferiority and superiority met
2-yr OS: 99% vs 91%, P=.02
2-yr DFS: 97% vs 90%, P=.11
Update (Platzbecker, JCO 2017) 2-yr EFS: 98.2% vs 86.0% (diff 12.2%, 95%CI 4.3-20.1, P<.001)
Update 2-yr OS: 99.2% vs 94.8%, P=.0073
2-yr OS: 99% vs 91%, P=.02
2-yr DFS: 97% vs 90%, P=.11
Update (Platzbecker, JCO 2017) 2-yr EFS: 98.2% vs 86.0% (diff 12.2%, 95%CI 4.3-20.1, P<.001)
Update 2-yr OS: 99.2% vs 94.8%, P=.0073
Adverse events
Hematologic/cytopenias: Prolonged neutropenia and thrombocytopenia significantly more frequent with chemotherapy (Arm B), P<.001.
Infections: Febrile neutropenia episodes 30 vs 75 during induction (A vs B), P<.001.
Hepatic/cardiac: Grade ≥3 LFT elevation 44% vs 3% (A vs B), P<.001; QTc prolongation 15 vs 1 patients, P<.001 (ATO arm).
Differentiation syndrome: 19% vs 16%, P=.62; severe in 10 patients (5 per group), fatal in 2 (Arm B). Prophylaxis: prednisone 0.5 mg/kg/d; if suspected, hold ATRA/ATO and give dexamethasone 10 mg BID.
Infections: Febrile neutropenia episodes 30 vs 75 during induction (A vs B), P<.001.
Hepatic/cardiac: Grade ≥3 LFT elevation 44% vs 3% (A vs B), P<.001; QTc prolongation 15 vs 1 patients, P<.001 (ATO arm).
Differentiation syndrome: 19% vs 16%, P=.62; severe in 10 patients (5 per group), fatal in 2 (Arm B). Prophylaxis: prednisone 0.5 mg/kg/d; if suspected, hold ATRA/ATO and give dexamethasone 10 mg BID.
Conclusions
ATRA+ATO was non-inferior (and on update superior) to ATRA+chemotherapy in newly diagnosed low/intermediate-risk APL, with substantially less hematologic toxicity, establishing a chemotherapy-free standard.
Key Limitations
Restricted to low/intermediate-risk APL (WBC <10K); not applicable to high-risk disease. Open-label. ATO arm requires QTc and hepatic monitoring; cumulative ATO exposure burdensome. Limited representation of older/comorbid patients.
Clinical Context
Practice-changing: ATRA+ATO is the ESMO/ELN-endorsed standard of care for newly diagnosed low/intermediate-risk APL, supporting FDA/EMA use of arsenic trioxide in frontline APL. High-risk APL typically adds gemtuzumab ozogamicin or anthracycline.