Biosimilars Expand Access and Cut Costs in HER2-Positive Cancer Treatment

Biosimilar versions of trastuzumab have rapidly gained market share in treating HER2-positive breast cancer since their introduction to the US markets, according to a study published in the Journal of Managed Care & Specialty Pharmacy.

Biosimilars are biologic drugs that closely replicate the safety and efficacy of Food and Drug Administration (FDA)-approved reference biologics, such as trastuzumab. Approved in 1998, trastuzumab revolutionized the treatment of HER2-positive cancers. However, its high cost, stemming from complex manufacturing processes, limits accessibility for many patients. Despite being approved for use in the US in 2017, utilization data on trastuzumab biosimilars are limited.

“We therefore conducted the present study to assess use patterns and characteristics of patients treated with trastuzumab biosimilars, relative to the reference and other HER2 products, in a large, geographically diverse, and commercially insured patient population in the United States,” explained Xiaodan Mai, PhD, MBBS, Harvard Pilgrim Health Care Institute and Harvard Medical School in Boston, MA, and coauthors.

The researchers conducted a retrospective, noninterventional cohort study using data from the Biologics and Biosimilars Collective Intelligence Consortium (BBCIC). They analyzed real-world utilization of trastuzumab and its biosimilars among over 16 million patients with HER2-positive cancers between 2016 and 2022. Results showed that biosimilars now account for a growing share of HER2 treatment episodes, with trastuzumab-anns alone increasing from 2% of use in 2019 to 37.5% by 2022.

The study also highlighted the demographic and clinical profiles of patients using HER2 inhibitors. The mean age of those who were treated with trastuzumab was approximately 60 years, with over 90% of episodes occurring in women. Clinical characteristics, including obesity, diabetes, and hypertension, were similar across users of reference trastuzumab and its biosimilars.

Interestingly, the study revealed that reference trastuzumab use declined sharply, from 96.3% of episodes in 2016 to just 15.8% in 2022, reflecting a broader shift toward cost-effective biosimilars. Despite these trends, gaps remain in understanding real-world outcomes and patient preferences regarding these newer therapies.

“There is a need for postmarketing safety surveillance evaluation of biosimilars as more of these products are introduced to the market,” the authors concluded. “In addition, assessment of the comparative effectiveness of these drugs would be important to inform clinical decision-making for optimal treatment selection for individual patients and represents a priority area of focus for the BBCIC.”

Reference

Mai X, Mendelsohn AB, Marshall J, et al. Utilization and patient characteristics for the trastuzumab reference and biosimilars, and other human epidermal growth factor receptor 2 inhibitors in the United States. J Manag Care Spec Pharm. 2024;30(10):1160-1166. doi:10.18553/jmcp.2024.30.10.1160