This protocol applies to patients with high-risk acute promyelocytic leukemia — defined by a white blood cell count above 10,000/ml — who completed consolidation with ATRA/ATO but did not reach the molecular remission endpoint of PML-RARA negativity by PCR.
High-risk APL is defined by WBC >10,000/ml at presentation. In the ATRA era, APL is stratified by WBC count; most clinicians place patients with WBC >10,000/ml in a high-risk category associated with a distinct relapse profile and a more intensive treatment course.
The preceding step was consolidation with ATRA/ATO (all-trans retinoic acid combined with arsenic trioxide), given to patients successfully induced with ATRA/ATO and an anthracycline. Progression to this protocol is indicated when that consolidation failed to achieve the defined molecular target: PML-RARA negative by PCR at end of consolidation.
This protocol involves a structured oral maintenance phase extending up to 2 years. The complete regimen — including specific agents, dosing, schedule, and monitoring parameters — is available in the full structured protocol below.
DOI: 10.3389/fonc.2022.1062524
In the era of ATRA, APL has been stratified into three categories of risk with regards to relapse-free survival (RFS): WBC >10,000/ml (high-risk), WBC ≤10,000 ml with platelet count ≤40,000/ml (intermediate-risk), and WBC ≤10,000/ml with platelet count >40,000/ml (low-risk).
Today, most clinicians will categorize APL within two categories, high risk (>10,000/ml) and low/intermediate risk.
Maintenance therapy including ATRA, methotrexate, and 6-mercaptopurine (6-MP) is included for high-risk patients in the widely utilized APML4 protocol and omitted for low/intermediate-risk patients.
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