Pattern of chronic myeloid leukemia in the imatinib era in a Sub-Saharan African setting

Abstract

Chronic myeloid leukemia (CML) is an orphan disease in Africa because of the inaccessibility to specific treatment and the high cost of diagnosis and monitoring patients. The aim of this study was to report CML treatment response in a developing country in the tyrosine kinase inhibitor era. We conducted a longitudinal study of our cohort of CML patients. Socio-demographic, diagnosis, therapeutic, and treatment response parameters were studied. Sokal score, disease phase at diagnosis, delay from diagnosis to treatment, and treatment response were analyzed for their impact on survival. Fifty-five patients with a diagnosis of CML and who received treatment with imatinib for a minimum of 3months were included in this study. Median follow-up was 170 patient-years. The sex ratio (M/F) was 1.62 and median age at diagnosis was 42years. At diagnosis, 85.5% of the patients were in chronic phase (CP), 12.7% in accelerated phase (AP), and 1.8% in blast crisis (BC). Sokal risk score distribution was as follows: low risk 29.8%, intermediate risk 38.3%, and high risk 31.9%. Median time from first symptoms to first medical visit was 6.2months and median time from first medical visit to cytogenetic and or molecular confirmation was 12.4months. Mean delay time from first medical visit to imatinib initiation was 12.5months (95% CI 6.3-18.7). The complete hematologic response (CHR) at 3months, the major cytogenetic response (MCR) at 12months, and the major molecular response (MMR) at 24months were respectively 82.4, 75, and 25%. The 2-year overall survival rate was 81%. Advanced phase at the diagnosis, discontinuation of imatinib therapy over 15% of the time, lack of CHR at 3months, lack of MCR at 12months, and progression of the disease during imatinib therapy were associated with a risk of death (p ≤ 0.05). Our data confirm the improved prognosis of CML treated with imatinib in the setting of a developing country. However, response rates are lower than in developed countries, and additional efforts should be made to facilitate early diagnosis and improve access to TKI, treatment compliance, and regular molecular monitoring of patients.