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The Role of Biosimilars in Oncology: A Physician’s Perspective

Sixth Issue 2013 series: Conquering the Cancer Care Continuum

In April 2011, the National Comprehensive Cancer Network (NCCN) convened a summit of key stakeholders regarding the issues surrounding biosimilars in oncology care. The working group subsequently published a sentinel white paper outlining the regulatory, scientific, and patient safety issues surrounding the development and expansion of biosimilars in oncology care.1 A fundamental rationale for figuring out the biosimilars issues relates to costs. Of the nearly 200 agents listed in the NCCN compendium in 2011, 15% were classified as biologics,1 and this number is continuing to grow each year. Of the top 20 anticancer drugs in terms of expenditures in 2010 (not including supportive care medications), 5 (25%) were biologics (bevacizumab, rituximab, trastuzumab, cetuximab, and panitumumab), but they led to 55% of the total costs.2

Beth Faiman and Steve Stricker both focus on filgrastim in their very well-written and thought-provoking articles. Filgrastim, a growth factor stimulant, is a key supportive medication in the care of many oncology patients. Usage varies by disease type, chemotherapy regimen used (ie, febrile neutropenia potential), and stage of disease. The considerations for accepting filgrastim biosimilars are similar to many of the issues surrounding antineoplastic biosimilars. As discussed in the previous articles, biosimilars are “similar but not identical.” When considering use of biosimilars that are not identical to the original drug, we would like to say they are equal in efficacy. However, demonstrating true equivalence in clinical research is a near-impossible task, but clearly, as providers, we want to be sure that substituting one drug for another drug leads to nearly equivalent drugs, accepting that some small margin of difference is likely inevitable. And while this is certainly important with supportive medications like filgrastim, it may be an even higher concern with antineoplastic therapies.

At the NCCN 16th Annual Conference in March 2011, 277 conference attendees were surveyed on their knowledge of biosimilars.1 Approximately 50% of these were physicians, 25% nurses, 14% pharmacists, and 11% other. Only 4 questions were asked of respondents, but the answers were telling. Fifty-four percent were not familiar or only slightly familiar with the recent developments in biosimilars (ie, the recent legislation outlining an abbreviated approval pathway). The group most familiar with the changes was pharmacists, and the group least familiar was nurses, with physicians in the middle. Interest in prescribing biosimilars was high (>60% had high and moderate interest). Multiple data pieces were very or somewhat impor­tant to respondents, with >80% indicating the importance of studies showing chemical/physical similarities, studies showing pharmacokinetic similarities, inclusion in compendium, data on cost differences, understanding of payer decisions and requirements, and colleague and/or expert opinions. For each top-used biologic available at the time, approximately 20% of respondents would immediately use the biosimilar if available today, ~60% would require review and discussion prior to using, and 5% to 8% would not use the biosimilar if available today.

This last question may raise some of the most telling issues related to this subject. Sixty percent of respondents required further review of a biosimilar prior to using. The question is what data would they want? What data would be compelling? Efficacy alone? Safety? Costs? These are key questions to understand in how these biosimilars will be incorporated into clinical practice. I think also telling is that 5% to 8% of providers will not use the biosimilar despite being approved and available. Why? This issue is raised by Steve Stricker in his article – one presumes it is primarily driven by concerns for efficacy and safety, although some providers are also considering the potential lower reimbursement and margin for biosimilars. This latter point remains an issue in oncology (as well as other fields of medicine) that requires further scrutiny as attempts are made to bring down healthcare costs.

In summary, I think many of us assumed that when drugs like filgrastim and rituximab (as 2 examples) entered the market 22 and 15 years ago, respectively, generics would come down the pike just as we have seen for traditional chemotherapies. However, as discussed in this issue of Conquering the Cancer Care Continuum, issues around biosimilars are many and complex in nature. However, all stakeholders involved realize that we cannot ignore the issue anymore. Biosimilars are essential to continuing to provide high-quality, cost-effective, and compassionate care to our patients.


  1. Zelenetz AD, Ahmed I, Braud EL, et al. NCCN Biosimilars White Paper: regulatory, scientific, and patient safety perspectives. J Natl Compr Canc Netw. 2011;9(suppl 4):S1-S22.
  2. Doloresco F, Fominaya C, Schumock GT, et al. Projecting future drug expenditures: 2011. Am J Health Syst Pharm. 2011;68:921-932.

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