Abstract Single centre experience of the adoption of self-administered HER2-directed therapy in patients with breast cancer Background: Programs to promote the self-administration of systemic anti-cancer therapy (SACT) offer greater convenience and shared decision making for patients with the opportunity to alleviate pressures on cancer services. Aims and Objective: The aims of this study were to quantify the uptake/acceptability of self-administration (SA) of subcutaneous trastuzumab (sc T), to evaluate safety, patients’ perception of the programme and the chair capacity released as a consequence. Methods: Patients receiving T for the treatment of HER2 +ve breast cancer were offered training in SA. The competency-based training programme, under the supervision of a chemotherapy-trained nurse, consisted of a minimum of 3 training sessions. Patients were also provided with printed and electronic material (via an App) on how to self-administer sc T, with 24/7 contact details in the event of an adverse event or device failure. Once trained and deemed competent, sc T was shipped to the patients’ home in a temperature-controlled environment, in a pre-filled syringe. All patients were assessed by telephone one day before and one day after SA using the Common Terminology Criteria for Adverse Events (CTCAE). Analysis of the total number of administrations of sc T, between February 2022 and June 2023 was conducted. A telephone survey using a validated questionnaire Self-Management Assessment scale (SMASc) was also undertaken. Results Of 46 breast cancer patients receiving single agent sc T, 32 agreed to participate in the program and were trained. 2 patients were undergoing training at data analysis. 6 patients declined and 6 were ineligible for the programme on the basis of inclusion criteria. The median age of the 32 patients that participated was 62, (range 27-77). The average distance from their home address to the cancer centre was 11.7 miles (range 3.5-27.9). 25 (78%) patients were Caucasian, 4 (13%) were Asian and 3 (9%) were of African/Caribbean origin. Patients had received an average of 10 sc injections in the hospital environment (median 5, range 1-103) before starting the training sessions. They required an average of 3 training sessions before sign-off (median 3, range 1-4). In the 32 patients studied, a total of 302 SA injections were delivered median 9 (range 1- 24) No Grade 3 or 4 CTCAE toxicities or infusion-related reactions were reported. During the 17-month period, a total of 302 hours of chair time was saved. 25 of the 32 patients responded to SMASc questionnaires utilising the six-point Likert scale. Patients reported average scores of 5.32 (median 6) and 5.56 (median 6) respectively, for questions relating to having information about their condition and sufficient training to self-administer. They felt that they had sufficient support to participate in the programme (average 5.56 median 6). 80% of the patients would recommend this programme and 88% felt they had benefited. Comments from patients themed around the value of the support provided, ease of administration and time saved. Discussion Programs such as these empower patients and carers to take a more active role in managing their condition with consequent reduced hospital attendance. Safety and acceptability for those patients who agreed to the program has been confirmed. Success of this program with sc T has enabled expansion to incorporate self-administration of Phesgo (sc trastuzumab and pertuzumab) with 31% (14/45) of the current P patient cohort enrolled onto the programme within 2 weeks of roll out and the first patients self-administering their treatment from August 2023. With the continued expansion of SACT treatments, we encourage stakeholders to consider self-administration of SACT as an option. Formulation of treatments conducive to patient self-administration is a key component to this. Citation Format: Wendy Ng, Vikash Dodhia, Amy Guppy, Stephanie Sutherland, Marlgozata Wojtas, Karen Harrold, Adisa Aolat, Tome Tapiwa, David Miles. Single centre experience of the adoption of self-administered HER2-directed therapy in patients with breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-11-01.