Cedars-Sinai Health System had a 55% biosimilar substitution rate for its reference bevacizumab, rituximab, and trastuzumab agents prior to January 2021. At the American Society of Community Oncologists 2022 annual meeting, a poster presentation detailed a project to increase the health system’s biosimilar substitution rate substantially across its medical center and affiliated practice sites.
None of these biosimilars, of course, are designated as interchangeable by the Food and Drug Administration, and automatic substitution is therefore not possible. The pharmacy team at Cedars-Sinai decided to leverage the electronic health record (EHR) system to encourage prescribers to utilize the available oncology biosimilars (as chosen by the system’s oncology Pharmacy & Therapeutics Committee). The EHR presented clinical pathway information for the individual cancers and included comparative medication cost for the preferred biosimilar versus the reference biologic. The physician could still prescribe the reference product through an opt-out process.
The goals for the project were to achieve a biosimilar substitution rate of 80% at the medical center and a rate of 75% at its three affiliated sites. Five hundred thirty-five patients with cancer who used regimens containing bevacizumab, rituximab, or trastuzumab (culled from 811 patients in total) throughout 2021 were included in the analysis. This included 267 patients treated at the medical center, and 52–158 patients treated at the affiliated practices.
The researchers found an overall biosimilar substitution rate of 83% (a 51% improvement over the baseline 55% rate). The medical center had an 85% substitution rate and the affiliated sites had a biosimilar substitution rate of 81%. Across all practice sites, rituximab was substituted in 90% of eligible patients, followed by trastuzumab (87%), and bevacizumab (72%). They reported that one affiliated practice (n=52) had a bevacizumab substitution rate of only 33%.
When physicians opted out of prescribing the biosimilar, they were asked to provide reasons for preferring the reference agent. The most common reasons cited in the 92 patients given either Avastin®, Rituxan®, or Herceptin® were off-label indication (35%), differences in patient assistance programs (17%), differences in payer formulary coverage (15%), and clinician’s personal preference (12%).
The pharmacists estimated savings of an average of 23% based on wholesale acquisition costs (WAC) , or $1.2 million per month to the health system. They did not offer savings calculations based on other than a WAC basis, which does not reflect true costs.
