Abstract PS9-63: Real World Data on the Adoption of Trastuzumab Biosimilars in the Treatment of HER2-positive Breast Cancer

Abstract Background: Biosimilars for trastuzumab were introduced into the US market for the treatment of HER2-positive breast cancer in 2019, with the goal of providing the clinical benefit of the brand product at a lower price (increased value). Adoption of trastuzumab biosimilars may be affected by multiple factors, including physician confidence in biosimilar efficacy and efficacy across stages, practice reimbursement, payer medical policy/redirection. To look at the adoption of trastuzumab biosimilars in the US medical oncology community, we queried a database of submitted treatment plans for patients with breast cancer. Methods: Data from a pre-authorization platform used by multiple commercial insurance companies in the US (NantHealth Eviti) was analyzed. Cases were identified from approved treatment plans for patients with breast cancer by inclusion of brand trastuzumab or trastuzumab + hyaluronidase-oysk, or trastuzumab biosimilars. Results: As of July 1, 2020, 10,557 treatment plans trastuzumab-based therapy were submitted, 1740 (16.5%) of which used a trastuzumab biosimilar. Adoption of trastuzumab biosimilars increased over time, from 1.6% (27/1676) treatment plans in Q3-2109 to 43.3% (753/1736) in Q2-2020. No clear differences were observed between use in stage 0-IIIc disease (17.4%) vs stage IV/recurrent disease (14.5%). Using the July 1, 2020 CMS pricing for these drugs at normalized dose of 440 mg for trastuzumab/trastuzumab biosimilars or 600 mg of trastuzumab + hyaluronidase, the average cost/cycle/patient for brand therapy and biosimilar therapy is $4502 and $3618, respectfully, representing a savings of $1,374,620/cycle across the biosimilar-treated population. Additional analyses to be presented will include Q3 2020 utilization and patterns of utilization across payers with/without medical policy favoring biosimilars. Conclusions: Adoption of trastuzumab biosimilars in this commercial population has been rapid since their introduction. Use of these drugs provides a substantial opportunity for societal savings in the treatment of HER2-positive breast cancer. Citation Format: William A Flood, Tiffany Avery, Vlad Kozlovsky, Neil Margolis, Sandeep Reddy. Real world data on the adoption of trastuzumab biosimilars in the treatment of HER2-positive breast cancer [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS9-63.