Gleevec has been the cornerstone of CML treatment for the past 15 years. However, the introduction of a generic formulation (imatinib) has made patients and physicians uncertain about the medications that are being used, according to The CML Advocates Network, a network of CML patient organizations in over 70 countries (Geissler and colleagues. Leukemia 2016; epublished August 3, 2016).
The CML Advocates Network surveyed patient advocacy groups in 80 countries and physicians registered with the International CML Foundation about the introduction of generic imatinib. The Network then hosted a global advocacy meeting in 2014 to develop recommendations. At the time of the survey, Gleevec was available in 55 countries, Tasigna in 44 countries, Sprycel in 30 countries, Bosulif in 6 countries and Iclusig in 4 countries. By 2014, generic copies of Gleevec or Sprycel were available in 32 countries, including Canada.
One concern was that some countries permit generic formulations that are only chemically similar to the original drug; bioequivalence (i.e. comparable effects in the body) may not be a requirement for drug approval. This may explain, in part, why there have been reports of a loss of therapeutic response and more frequent side effects after switching to generic imatinib (Mattar M. Int J Hematol 2010;91:104-106. Uyanik and colleagues. Eur J Cancer Care 2015; epublished November 23, 2015).
Based on its discussions, the Network developed 5 recommendations to address the uncertainty people have about generic CML medications:
- No CML patient should be given a generic drug unless it has been shown to have reliable quality and proof of bioequivalence.
- Regulatory bodies (such as Health Canada or the FDA) should demand studies that directly compare generic and brand-name drugs to ensure that the generic has the same safety and effectiveness as the original.
- CML patients should not be switched to a generic if they have already responded optimally to the original drug and are able to tolerate it.
- If a CML patient is switched to a generic for non-medical reasons, this should not happen more than once a year. People should be monitored closely after switching to ensure that the new drug is safe and effective. If a person shows a loss of response, they must have the option of going back to the original drug or switching to another treatment.
- People who are switched to a generic should have more frequent molecular monitoring to ensure early detection of any loss of treatment response.
The group noted that the use of less expensive generics has the potential to expand the number of people who will have access to medication. However, they concluded that because of the uncertainty felt by many patients and prescribers, more data are needed to guide the switch to cheaper generics. This would help to ensure that the risks of losing treatment response or drug toxicities are minimized.