Efficacy suboptimal with first-line generic imatinib

Clin Lymphoma Myeloma Leuk, February 2017; advance online publication

medwireNews: The efficacy of imatinib can be maintained when switching from a branded to generic formulation, but may be reduced when the generic drug is used as a first-line treatment for chronic myeloid leukemia (CML), show results of a study from Bosnia and Herzegovina.

In the study, which analyzed the long-term clinical outcomes of generic imatinib, patients received either front-line generic imatinib for newly diagnosed CML (group 1, n=27) or second-line generic imatinib following a mandated switch from first-line therapy with the branded version of the drug (group 2, n=14). They were followed-up for 36 months overall, with median durations of 16 and 36 months in groups 1 and 2, respectively.

At 3 years, patients in group 1 had an overall survival rate of 85% and a complete cytogenetic response (CCyR) rate of 81%, while just under half (48%) achieved a major molecular response (MMR) at 24 months.

In addition, 52% of group 1 patients switched from first-line generic imatinib to nilotinib due to treatment failure and side effects during the course of the study.

By comparison, 3-year overall survival was 100% in group 2, with 93% of patients retaining both CCyR and MMR after switching from branded to generic imatinib. Just one (7%) patient switched to nilotinib after losing CCyR at 12 months.

Amina Kurtovic-Kozaric (Clinical Center of the University of Sarajevo, Bosnia and Herzegovina) and co-authors of the study suggest that the better outcomes observed among the patients in group 2 were likely due to the long period of treatment with branded imatinib (median 54 months) prior to switching to generic imatinib.

“This is in line with findings that demonstrated that achieving deeper molecular response at any time positively affects maintaining the cytogenetic and molecular responses, and decreases the transformation to accelerated and/or blastic phase,” they write in Clinical Lymphoma, Myeloma and Leukemia.

The researchers conclude that “generic imatinib as second-line does not have deleterious effects on patient outcomes, and that treatment with second-line generic imatinib had comparable clinical outcomes to branded imatinib.”

But add that “first-line generic imatinib indicated suboptimal efficacy in comparison to the branded imatinib.”

By Laura Cowen, medwireNews reporter

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