Molecular Response to Treatment of Chronic Myeloid Leukemia at University Teaching Hospital of Kigali, Rwanda: One-Arm Open Label Prospective Observational Study.

Background: Chronic myeloid leukemia (CML) is among most common chronic hematological neoplasms marked by proliferation of granulocytes. Since 2001, the introduction of tyrosine kinase inhibitors (TKI), especially imatinib, the outcomes for patients with CML has improved significantly, and life expectancy is now almost the same as that of general population in developed countries. However, this is not the case in the developing world owing to the limited access to TKI. In Rwanda only imatinib is available and molecular response assessment is limited. This study describes the molecular responses of patients with CML treated with imatinib in Rwanda. Methods: This one-arm, open-label, prospective cohort study recruited 31 patients with CML who had been on imatinib for ≥ three months. Patients were followed-up for 12 months. Clinical features and laboratory results at the time of diagnosis were retrieved from hospitals' records. Clinical re-assessment, full blood count, and BCR::ABL1 testing were done at the time of recruitment. Data analysis was performed using SPSS 28. Results: Using European LeukemiaNet BCR::ABL1 thresholds depending on time on imatinib; optimal, warning and failure (=resistance to imatinib) response categories were found in 38.7%; 16.1% and 45.2% respectively. The 12-month survival rate was 93.5% (n=29/31), all deaths (2/31) occurred in treatment failure group. Patients with late presentation (white blood cell counts >100x10 Conclusion: Although the 1-year survival rate was good for patients with CML treated with imatinib, the molecular response was generally poor. This may be due to late presentation and poor adherence to imatinib which needs further investigations. To improve the survival of patients with CML in Rwanda, access to all available lines of TKI and better follow-up should be considered.