How should childhood acute lymphoblastic leukemia relapses in low-income and middle-income countries be managed: The AHOPCA-ALL study group experience.

BACKGROUND: Children with relapsed acute lymphoblastic leukemia (ALL) in low-income and middle-income countries rarely survive. The Pediatric Hematology-Oncology Association of Central America (AHOPCA) developed the AHOPCA-ALL REC 2014 protocol to improve outcomes in resource-constrained settings without access to stem cell transplantation. METHODS: The AHOPCA-ALL REC 2014 protocol was based on a modified frontline induction phase 1A, a consolidation therapy with six modified R-blocks derived from the ALL-Berlin-Frankfurt-Munster REZ 2002 protocol and intermittent maintenance therapy. Children with B-lineage ALL were eligible after a late medullary relapse, an early or late combined relapse, or any extramedullary relapses. Those with T-lineage ALL were eligible after early and late extramedullary relapses, as were those with both B-lineage and T-lineage relapses occurring at least 3 months after therapy abandonment. RESULTS: The study population included 190 patients with T-lineage (n = 3) and B-lineage (n = 187) ALL. Of those with B-lineage ALL, 25 patients had a very early extramedullary relapse, 40 had an early relapse (32 extramedullary and 8 combined), and 125 had a late relapse (34 extramedullary, 19 combined, and 72 medullary). The main cause of treatment failure was second relapse (52.1%). The 3-year event-free survival rate (± standard error) was 25.9% ± 3.5%, and the 3-year overall survival rate was 36.7% ± 3.8%. The 3-year event-free survival rate was 47.2% ± 4.7% for late relapses. The most frequently reported toxicity was grade 3 or 4 infection. Mortality during treatment occurred in 17 patients (8.9%), in most cases because of infectious complications. CONCLUSIONS: Selected children with relapsed ALL in Central America can be cured with second-line regimens even without access to consolidation with stem cell transplantation. Children in low-income and middle-income countries who have lower risk relapses of ALL should be treated with curative intent.