Standard ‘7+3’ Induction in Newly Diagnosed Acute Myeloid Leukaemia: A Prospective Single-Centre Experience from a Resource-limited Setting

Background: Acute myeloid leukaemia (AML) is the most common acute leukaemia in adults. The standard induction regimen is the '7+3' combination of cytarabine and an anthracycline. Data on treatment outcomes from resource-limited settings remain sparse. This study aimed to describe the clinical features, laboratory parameters, and outcomes of induction chemotherapy with the 7+3 regimen in patients with newly diagnosed AML in Bangladesh. Methods: This prospective observational study was conducted at Sir Salimullah Medical College Mitford Hospital from December 2016 to November 2017. Patients aged 12-60 years with newly diagnosed AML (excluding acute promyelocytic leukaemia) who were suitable for intensive chemotherapy were enrolled. All patients received standard 7+3 induction (cytarabine 100 mg/m² continuous infusion days 1-7; daunorubicin 60 mg/m² days 1-3). Response assessment was performed on day 28 or later, following recovery of the neutrophil count to greater than 1.0 × 10⁹/L and the platelet count to greater than 100 × 10⁹/L. Results: Twenty patients were enrolled. The median age was 30.5 years (range, 16-52); 75% were younger than 40 years. The male-to-female ratio was 1.86:1. Fatigue (85%) and fever (75%) were the most common presenting symptoms. The median symptom duration before diagnosis was 6 weeks. FAB M2 was the predominant subtype (55%). On immunophenotyping, CD13 and CD33 were expressed in 90% of cases; aberrant lymphoid antigen expression occurred in 45%. Eight patients (40%) achieved CR; seven (35%) achieved partial remission. Treatment-related mortality was 20%, with 75% of deaths occurring within 10 days of chemotherapy initiation. Almost all patients (88%) achieving CR were younger than 40 years. Elevated lactate dehydrogenase (P=0.022) and FAB M2 subtype (P=0.025) were significantly associated with favourable outcomes. Minimal residual disease assessment was performed in 10 of 15 evaluable patients; 8 (80%) achieved MRD negativity. Grade 3 or higher adverse events included febrile neutropenia (100%), thrombocytopenia (100%), severe anaemia (70%), and severe bleeding (35%). Conclusions: Standard 7+3 induction achieved a CR rate of 40% with treatment-related mortality of 20% in this resource-limited setting. Results among younger patients were encouraging. The excess early mortality compared with high-income countries appears attributable to supportive care deficits, suggesting that improvements in infection control and transfusion services may enhance outcomes.