“The study supported a toxicity profile that was worse with generic imatinib compared [with] brand-name, and that’s a frustrating result, given that it hasn’t lived up to expectations for decreasing cost like some providers and patients would’ve hoped,” said Stephen Medlin, DO, of Aurora Cancer Care in Milwaukee, Wisconsin, in an interview with Cancer Therapy Advisor.

“At the same time,” he added, “going back to brand-name imatinib feels like going in the wrong direction. Intolerance caused many of the switches, but it wasn’t unbearably high. I don’t think the study changes a treatment algorithm that starts with generic imatinib.”

His thoughts were echoed by a leader in the field of CML treatment who feels that much of this conversation around generic imatinib is “noise driven by drug companies that own certain patents.”

“In my view, generic imatinib is as safe and as effective [as brand-name imatinib],” said Hagop Kantarjian, MD, chair of the department of leukemia at the MD Anderson Cancer Center, in an interview. “At MD Anderson, we use generic imatinib frontline. It should be frontline therapy on all newly diagnosed patients with CML.”

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The authors wrote that “BI users were censored upon switching to GI, because this switch was required by insurers and thus did not represent nonpersistence.” But this explanation does not address BI users that could have the potential to become nonadherent in the future as a result of the costs associated with the branded product. It was unclear how the cost differences of the medications could impact patient adherence in the long term.

The study does not appear to discuss patient blinding, so it’s unclear if all patients taking GI knew that they were not given the branded version of imatinib. The authors explained this potential participant bias in the following way: “While it could be argued that some patients had a predetermined notion to stop taking GI and therefore reported intolerance, the switching from GI still reflects real-world choices made by patients.”

In addition, the authors noted that they did not stratify GI users by manufacturer, which they recognized was a limitation — and very few patients actually did actually discontinue use of a GI medication overall, which the authors wrote “decreased the precision around this secondary analysis.”

For his part, Dr Klil-Drori stressed the differences between the American and Canadian health care systems in deciding to prescribe and to reimburse these drugs, stating, “I’d love to see a similar study come from the United States — where the cost and the picture is different — that reflects [patients’] own experiences with generic imatinib availability.”

References

  1. Klil-Drori AI, Yin H, Azoulay L, et al. Persistence with generic imatinib for chronic myeloid leukemia: a matched cohort study. [published online January 10, 2019]. Haematologica. doi: 10.3324/haematol.2018.211235
  2. Eliasson L, Clifford S, Barber N, Marin D. Exploring chronic myeloid leukemia patients’ reasons for not adhering to the oral anticancer drug imatinib as prescribed. Leuk Res. 2011;35(5):626-630.
  3. Verbrugghe M, Duprez V, Beeckman D, et al. Factors influencing adherence in cancer patients taking oral tyrosine kinase inhibitors: a qualitative study. Cancer Nurs. 2016;39(2):153-162.