Background Biologics, such as trastuzumab (Herceptin) for HER2+ breast cancer, have been revolutionary in improving survival for early stage and metastatic disease. However, their high cost increases cancer care expenses. Recent approval of trastuzumab biosimilars is promising in terms of cost savings and health benefits of access to life-saving treatment for more patients. Although clinical trials have demonstrated equivalence in efficacy and safety between biosimilars and the reference drug, multiple barriers to uptake have been identified. Ours is the first survey comparing the experiences and perspectives of oncologists and patients. Methods We developed a 60-item survey to characterize the experiences of US patients (with HER2+ breast cancer) and oncologists with trastuzumab biosimilar(s). Survey invitations were distributed via social media and data were collected using REDCap. Results From August 2020 to June 2021, 33 physicians and 143 patients (1 male) completed the survey. Average age was 49.72 years (SD = 10.95) for patients and 46.16 years (SD = 11.04) for oncologists. Respondents were (patients and oncologists, respectively) White (71%, 39%), Black (2%, 1%); and not Hispanic (71%, 82%). Over half of the patients (56%) reported having a bachelor’s degree and above and private insurance (58%). Half (55%) reported metastatic breast cancer; 85% having received treatment within the past year. About 56% reported being presented with an option to switch from biologic trastuzumab to biosimilar and 63% reported having switched. Of those who reported a switch, 40% received no prior notification. Using a scale of 0 (Disagree)-100 (Agree), we administered 13 matching questions to oncologists and patients about their experience (and perspective) with trastuzumab biosimilars. Patients reported lower ratings than oncologists, t(160) = 3.74, p = .006 (patients: M = 43.74, SD = 18.94; oncologists: M = 56.66, SD = 11.50). Smaller proportion of patients than oncologists responded positively (a score of >50) to all but 1 item (Table). About 44% of patients reported learning more about biosimilars through self-directed learning and 41% reported wanting more time to discuss with oncologist, achieving a better understanding of biosimilars (39%) and having access to printed materials (30%) and specifically, ones that are user-friendly (18%). Conclusions These findings highlight a discrepancy between patient-reported experiences and oncologist perceptions of the patient experience. Our findings suggest that lack of adequate information is a challenge not only to the uptake of trastuzumab biosimilars, but to the patient-oncologist relationship. There is a need for effective and tailored education for both oncologists and patients to facilitate communication regarding trastuzumab biosimilars, and to assure patients of safety and efficacy.

% respondents with scores of > 50 (0 (Disagree) - 100 (Agree))
Patients (n = 143)Oncologists (n = 33)
My oncologist explained a switch to biosimilar trastuzumab in a way that was easy to understand 42% 58% 
I feel/felt involved in this treatment decision to choose a biosimilar trastuzumab for me 17% 18% 
I trust my oncologist in making the right decision to choose a biosimilar trastuzumab for me 63% 67% 
I trust my insurance company in making the right decision to require biosimilar trastuzumab instead of Herceptin 9% 12% 
I trust my hospital/center in making the right decision to require biosimilar trastuzumab instead of Herceptin 41% 44% 
I was given the opportunity to ask questions about a switch to biosimilar trastuzumab 35% 59% 
I was given adequate resources on biosimilar trastuzumab to feel comfortable with a switch 18% 33% 
My cancer is/will be treated as effectively with biosimilar trastuzumab as with Herceptin 43% 79% 
I understand the reason for switching to biosimilar trastuzumab 43% 39% 
This treatment switch to biosimilar trastuzumab DOES NOT make me worried 24% 41% 
I have emotionally adjusted to this treatment switch that wasnt due to cancer progression or quality of life issues 41% 42% 
I DO NOT worry more about my treatment success since this switch to a biosimilar trastuzumab 29% 33% 
Switching to a biosimilar trastuzumab is a minor change to my cancer care 37% 67% 
Note: Presented are patient-framed questions. Oncologist questions were reframed accordingly.   
% respondents with scores of > 50 (0 (Disagree) - 100 (Agree))
Patients (n = 143)Oncologists (n = 33)
My oncologist explained a switch to biosimilar trastuzumab in a way that was easy to understand 42% 58% 
I feel/felt involved in this treatment decision to choose a biosimilar trastuzumab for me 17% 18% 
I trust my oncologist in making the right decision to choose a biosimilar trastuzumab for me 63% 67% 
I trust my insurance company in making the right decision to require biosimilar trastuzumab instead of Herceptin 9% 12% 
I trust my hospital/center in making the right decision to require biosimilar trastuzumab instead of Herceptin 41% 44% 
I was given the opportunity to ask questions about a switch to biosimilar trastuzumab 35% 59% 
I was given adequate resources on biosimilar trastuzumab to feel comfortable with a switch 18% 33% 
My cancer is/will be treated as effectively with biosimilar trastuzumab as with Herceptin 43% 79% 
I understand the reason for switching to biosimilar trastuzumab 43% 39% 
This treatment switch to biosimilar trastuzumab DOES NOT make me worried 24% 41% 
I have emotionally adjusted to this treatment switch that wasnt due to cancer progression or quality of life issues 41% 42% 
I DO NOT worry more about my treatment success since this switch to a biosimilar trastuzumab 29% 33% 
Switching to a biosimilar trastuzumab is a minor change to my cancer care 37% 67% 
Note: Presented are patient-framed questions. Oncologist questions were reframed accordingly.   

Citation Format: Elizabeth Lerner Papautsky, Martha Carlson, Maryam Lustberg. The patient-centered paradox: A US-based survey of physician- and patient-reported experiences with biosimilar trastuzumab [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-13-13.