Researchers have found that shifting from the original to a generic form of imatinib in treatment of chronic myeloid leukemia (CML) does not appear to compromise safety or efficacy. The results were recently reported in Cancer Medicine.

In this retrospective, observational study, records from the University of Texas MD Anderson Cancer Center were examined for patients who began treatment with the original form of imatinib between the years of 2000 and 2017.

Records were included for patients (N=38) with CML in the chronic phase who had undergone a switch from the original to a federally approved generic form of imatinib during the study period. Patient responses were compared from before and after the switch to the generic.

The median time on a generic form of imatinib was 19.4 months (range, 3.4 to 46.3 months). All patients reportedly showed complete cytogenetic response prior to shifting to generic imatinib, with 95% achieving major molecular response while receiving the original form of imatinib, and 74% showing a molecular response with a 4.5-log reduction.

The investigators reported that after changing to a generic, 89% of patients showed a stable molecular response, with improved responses for 8%, and a poorer response for 3%.

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A total of 39% of the patients experienced adverse events (AEs) that either newly appeared or became worse following the change to a generic form of imatinib. Most commonly, these AEs included muscle cramps in 21% of patients, nausea in 18%, and diarrhea in 16%. The authors reported that no grade 3 or 4 AEs occurred.

“Our results, albeit observational in nature, suggest that a switch from original imatinib to generic imatinib maintains efficacy and preserves safety,” wrote the investigators in their report. They noted that the study’s results are potentially not applicable to generic formulations available outside of the United States.

Reference

Abou Dalle I, Kantarjian H, Burger J, et al. Efficacy and safety of generic imatinib after switching from original imatinib in patients treated for chronic myeloid leukemia in the United States. [published online September 10, 2019]. Cancer Med. doi: 10.1002/cam4.2545