The Efficacy of Generic Imatinib as First- and Second-line Therapy: 3-Year Follow-up of Patients With Chronic Myeloid Leukemia

Introduction: Generics of imatinib mesylate, the first tyrosine kinase inhibitor targeting the BCR-ABL1 fusion protein, have recently been approved in many countries as the alternative, low-cost forms for the treatment of patients with chronic myeloid leukemia (CML). The aim of this study was to evaluate the long-term clinical outcomes of patients with CML receiving first-line and second-line generic imatinib in Bosnia and Herzegovina.

Patients and methods: This was a multicenter retrospective cohort study of patients (n = 41) treated with generic imatinib in Bosnia between September 1, 2013 and August 5, 2016. Patients were categorized into 2 study groups: Group 1 (n = 27) included newly diagnosed patients with CML receiving front-line generic imatinib, and Group 2 (n = 14) consisted of patients who started with front-line Glivec and were mandated to switch to the second-line generic imatinib.

Results: The median follow-up for Group 1 (first-line generic imatinib) and Group 2 (second-line generic imatinib) was 16 and 36 months, respectively. At 36 months, the overall survival for patients in Group 1 was 85%, and the achievement of complete cytogenetic response was 81%. At 24 months, the major molecular response rate was 48%. Overall, 52% of patients switched from first-line generic imatinib to nilotinib owing to treatment failure and side-effects. In Group 2, 93% of patients sustained cytogenetic and molecular response at 3 years after the switch from branded to generic imatinib.

Conclusion: Our results lead us to conclude that generic imatinib as second-line therapy does not have deleterious effects on patient outcomes. However, first-line generic imatinib showed suboptimal efficacy compared with branded imatinib.