Abstract PO3-05-14: Practice patterns for sequential use of antibody-drug conjugate after antibody-drug conjugate in metastatic breast cancer: results from a physician survey
Authors: Abdou Yara , Bhardwaj Prarthna , Abelman Rachel , Spring Laura , Bardia Aditya , Carey Lisa , Sharma Priyanka 
Published: May 2024

Abstract
Introduction: Antibody-drug conjugates (ADCs) have become a key part of metastatic breast cancer (MBC) treatment. Trastuzumab deruxtecan (T-DXd), and Sacituzumab Govitecan (SG) are approved ADCs available for the treatment of MBC. Completed trials that led to the approval of these ADCs did not include patients who had received the other ADC as prior therapy. Little is known about the optimal sequencing of these agents and how clinicians are incorporating ADC sequencing decisions at bedside. Methods: An online survey regarding the use of sequential ADCs was distributed electronically from April 2023 to July 2023 among US clinicians who treat patients with breast cancer. The survey included eight questions assessing clinician practice settings and the use of ADC sequencing and five case-based scenarios (table 1). Descriptive statistics were used to assess survey responses. Results: 107 survey responses were received, out of which 72% were female responders and 93% were medical oncologists. The majority of responders practiced in an academic setting (83%) and reported being involved in clinical research (82%). 58% of responders have been in practice for &gt;10 years and 68% treat &gt;20 breast cancer patients per week. 87% had prescribed an ADC post-ADC for MBC. 46% of responders thought that the degree of benefit for an ADC post-ADC would be similar to the benefit noted in the pivotal ADC trials, and 54% thought that the degree of benefit with sequencing would be lower than in the pivotal trials. Regarding the case-based questions for patients with triple-negative breast cancer and HER2 low disease who had disease progression on first-line metastatic therapy, 64-71% of clinicians opted to give SG as the first ADC followed by T-DXd as the second ADC in sequence, regardless of age, PDL1 status and prior metastatic therapies. For a patient with hormone-positive (HR+), HER2 low MBC, who had received capecitabine as the first metastatic chemotherapy, 50% opted to give T-DXd as the first ADC followed by SG as the second ADC, and 40% opted to give weekly paclitaxel followed by SG as the first ADC. For a patient with HR+, HER2 low MBC who had received two prior chemotherapies for metastatic disease, 77% opted for T-DXd as the first ADC, followed by SG as the second sequential ADC. When grade 1 pneumonitis was added as a comorbidity to the case, only 16% opted to give T-DXd as the first ADC choice. Conclusion: Almost 90% of clinicians report prescribing sequential ADCs for MBC, yet there is little uniformity in how these ADCs are sequenced. More than 50% felt that the benefit of the second ADC in the sequence will be lower than the registration trials that led to the approval of the ADC in a setting of no prior ADC treatment. The optimal sequencing of ADCs remains an area of unmet need and further studies are needed to guide optimal medical decisions regarding sequential ADC-based treatment algorithms for patients with MBC.
Table 1. Case-based scenarios for ADC sequencing
Citation Format: Yara Abdou, Prarthna Bhardwaj, Rachel Abelman, Laura Spring, Aditya Bardia, Lisa Carey, Priyanka Sharma. Practice patterns for sequential use of antibody-drug conjugate after antibody-drug conjugate in metastatic breast cancer: results from a physician survey [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 PO3-05-14.