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ABSTRACT: The introduction of all-trans retinoic acid combined with anthracyclines has significantly improved the outcomes for patients diagnosed with acute promyelocytic leukemia (APL), and this strategy remains the standard of care in countries in which arsenic trioxide is not affordable. However, data from national registries and real-world databases indicate that low- and middle-income countries (LMIC) still face disappointing results, mainly because of high induction mortality and suboptimal management of complications. The American Society of Hematology established the International Consortium on Acute Leukemias (ICAL) to address this challenge through international clinical networking. Here, we present the findings from the International Consortium on Acute Promyelocytic Leukemia study involving 806 patients with APL recruited from 2005 to 2020 in Brazil, Chile, Paraguay, Peru, and Uruguay. The induction mortality rate has notably decreased to 14.6% compared with the pre-ICAL rate of 32%. Multivariable logistic regression analysis revealed as factors associated with induction death: age of ≥40 years, Eastern Cooperative Oncology Group performance status score of 3, high-risk status based on the Programa Español de Tratamiento en Hematologia/Gruppo Italiano Malattie EMatologiche dell'Adulto classification, albumin level of ≤3.5 g/dL, bcr3 PML/RARA isoform, the interval between presenting symptoms to diagnosis exceeding 48 hours, and the occurrence of central nervous system and pulmonary bleeding. With a median follow-up of 53 months, the estimated 4-year overall survival rate is 81%, the 4-year disease-free survival rate is 80%, and the 4-year cumulative incidence of relapse rate is 15%. These results parallel those observed in studies conducted in high-income countries, highlighting the long-term effectiveness of developing clinical networks to improve clinical care and infrastructure in LMIC.

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Objetivo: Describir la respuesta terapéutica con un anticuerpo monoclonal anti CD20 (Rituximab), en pacientes con Trombocitopenia Inmune (PTI). Material y métodos: Estudio retrospectivo, descriptivo y observacional tipo serie de casos. Se revisaron las historias clínicas de pacientes adultos con PTI que recibieron el anticuerpo monoclonal anti CD20 (Rituximab), desde diciembre 2005 hasta diciembre 2010. Se definió respuesta: conteo plaquetario >30 mil, por lo menos duplicar el conteo plaquetario inicial y no signos de sangrado, y respuesta completa: conteo plaquetario >100 mil y no signos de sangrado. Resultados: Se evaluaron 24 cursos de tratamiento. Hubo respuesta en 18 (75%), en una media de 11,9 semanas (rango 0,7 û 37,4), la duración media de respuesta fue 16 meses (rango 3,3 û 55,3). Se mantuvo la respuesta obtenida en 12 pacientes, seguimiento promedio de 22 meses (rango 4 - 62). Se logró respuesta completa en 13/23 (60%) casos, en una media de 17 semanas (rango 0,7 û 62,3), con una duración media de respuesta completa de 10,1 meses (rango 2,3 û 25,2), 5 casos mantuvieron respuesta completa con una media de seguimiento de 20 meses (rango 8 û 29). Conclusiones: Se obtuvo una alta tasa de respuesta al tratamiento con Rituximab (hasta 75%) en casos de PTI que fallaron al menos a una línea de tratamiento.

Objective: To describe the therapeutic response of an anti CD20 monoclonal antibody (Rituximab) in patients with immune thrombocytopenia (ITT). Methods: Retrospective, descriptive and observational case series. The clinical charts of ambulatory patients with ITT who received Rituximab from December 2005 to December 2010 were reviewed. Response was defined as platelet count > 30 thousand, at least duplicate the initial platelet count and no evidence of bleeding, and complete response was defined as platelet count > 100 thousand and no evidence of bleeding. Results: 24 courses of treatment were evaluated. Response was obtained in 18 patients (75%); mean time to response was 11.9 weeks (range: 0,7 to 37.4); mean duration of response was 16 months (range: 3.3 to 55.3); 12 patients remained with the achieved response during a mean follow up of 22 months (range: 2.3 to 25.2). Complete response was obtained in 13/23 cases (60%); mean time to response was 17 weeks (range: 0.7 to 62,3); mean duration of response was 10,1 months (range: 2.3 to 25.2); 5 patients remained with complete response after a follow up of 20 months (range: 8-29). Conclusions: A high response rate was achieved with Rituximab (75%) in patients with ITT who had failed at least to one treatment.

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