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Characterizing experiences of non-medical switching to trastuzumab biosimilars using data from internet-based surveys with US-based oncologists and breast cancer patients



To characterize current experiences with communication and decision-making practices when non-medical switching to a biosimilar trastuzumab is proposed or required by cancer center or insurer.


We developed and launched 60- and 51-item internet surveys to elicit US breast cancer patient and medical oncologist lived experiences with trastuzumab biosimilars and patient information needs and seeking practices. We recruited participants using social media and administered via REDCap in 2020-2021.


143 breast cancer patients and 33 medical oncologists completed the surveys. 63.9% patients reported having switched to a trastuzumab biosimilar and 40.8% reported receiving no prior notification about switching. 44% of patients reported learning about biosimilars primarily through self-directed learning and 41% wanting more time to discuss with oncologist. None of the oncologists reported that the decision to switch a patient to a biosimilar was initiated by them, but rather more frequently by the insurer (45.2%). About 54.8% reported not receiving any pharmaceutical manufacturer material related to the selected biosimilar. Patients and oncologists diverged in their responses to items regarding patient opportunities to ask questions, adequacy of resources, effectiveness of treatment, patient worry, and magnitude of change.


There is a need for tailored and effective patient and oncologist information and education on trastuzumab biosimilars, along with improved healthcare communication regarding switching. The discrepancy between patient-reported experiences and oncologist perceptions of the patient experience, suggests a lack of adequate information that may be a challenge not only to the uptake of trastuzumab biosimilars, but to the patient-oncologist relationship.

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