This protocol targets patients with acute promyelocytic leukemia presenting with a white blood cell count above 10,000/ml — the threshold that defines high-risk APL. In the ATRA-era risk-stratification framework, this WBC level places patients in the category with the least favourable relapse-free survival, distinct from low/intermediate-risk APL.
The preceding induction step used all-trans retinoic acid (ATRA), arsenic trioxide (ATO), and an anthracycline. Its goals included hematologic normalization, molecular clearance of PML-RARA by the end of induction, resolution of bleeding symptoms, and stabilisation of coagulation parameters.
When these endpoints — in particular full molecular remission — have not been durably confirmed, or the patient has been successfully induced and now requires the next structured treatment phase, consolidation is the indicated next step.
For high-risk patients successfully induced with ATRA/ATO and an anthracycline, a specific combination consolidation strategy is available — one that involves ATRA/ATO-based therapy. The complete regimen, eligibility criteria, and supporting measures are detailed in the full protocol.
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.
It is now known that low/intermediate-risk patients achieve excellent outcomes with chemotherapy-free ATRA/ATO-based consolidation following ATRA/ATO-based induction, and that high-risk patients who are successfully induced with ATRA/ATO with an anthracycline can be consolidated with ATRA/ATO with the omission of chemotherapy.
The question remains, however, whether maintenance benefits high-risk patients induced with ATRA/ATO/anthracycline and consolidated with ATRA/ATO who are PML-RARα-negative by PCR at the end of consolidation.
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