The therapeutic advantage of the association of ATRA + Arsenic Trioxide is more favorable and manageable as compared to ATRA + chemotherapy. Nevertheless, at present, there is not enough information on the incidence of long-term side effects.

This study, as well as other similar studies conducted around Europe, will focus on following patients treated with this therapy on a long-term basis.

Once all studies in Europe will be concluded, all data will be analyzed together.

Considering the clear therapeutic advantage associated with ATRA+ATO combination therapy and the more favorable and overall manageable safety profile compared to ATRA+chemotherapy, the benefits of the combination in the first-line indication do appear to overweigh the risks.

However, no information regarding the actual adverse event (AE) incidence and the long-term toxicity of ATRA+ATO is available at present and therefore, as a postmarketing commitment, TEVA (the Company holding the Marketing Authorisation of Trisenox® (Arsenic trioxide)) is setting up a long-term safety cohort study of Trisenox in newly diagnosed low- to intermediate-risk APL patients retrospectively analyzing data from APL disease registries all around Europe.

As a result, this observational study is part of the retrospective PASS Study (A Post-Authorisation Long-Term Retrospective Safety Cohort Study of Arsenic Trioxide in First Line Low-to Intermediate-Risk Acute Promyelocytic Leukaemia Patients) that will use data from multinational APL disease registries in Europe. The present study will focus on Italian patients.

Inclusion Criteria:

• APL diagnosis based on cytological criteria and confirmed by the presence of the (15;17) translocation and/or the presence of the PML/RARA rearrangement (with the determination of the breakpoint subtype).
• Newly diagnosed low- to intermediate-risk APL (white blood cells [WBC] count ≤10x103/µL)
• First line treatment with ATRA+ATO
• Aged 18 years or above
• Signed informed consent, if applicable

Exclusion Criteria:

• High risk APL (WBC count > 10x103/µL)
• APL relapse

The Source Population for the study is patients included in existing multinational disease registries for APL in Europe. APL registries collect real-world data on APL demographics and provide information on disease characteristics, treatment patterns and long-term effects. Participating physicians are not subject to any instructions with regard to the diagnosis and therapy of their patients. All patient treatment is carried out within routine clinical practice at the discretion of the physician and according to existing treatment guidelines.

Data will be extracted from the registries for all patients meeting the above inclusion and exclusion criteria to provide the study population.