Opinions of real-world clinicians regarding visceral crisis in HR+/HER2- mBC: Results from the RETRACT survey of US oncologists.

e13081 Background: In approximately 10-15% of HR+/HER2- advanced breast cancer cases, the onset or progression of disease is sudden and accompanied by a rapid decline in organ functions and general health that can threaten the patient’s life, known as visceral crisis (VC). The ABC 5 international consensus guidelines define VC as “severe organ dysfunction, as assessed by signs and symptoms, laboratory studies and rapid progression of disease.” Few published studies have evaluated the opinions of real-world clinicians on the topic of VC in metastatic breast cancer (mBC), and the RETRACT (REal-world TReatment patterns And Considerations of Toxicity in HR+/HER2- mBC) survey of clinicians assessed this topic. Methods: The survey was distributed to clinical oncologists identified using an internal database and was accessible via an online digital platform using an invitation link and individualized credentials. Responses were collected from December 2023 through April 2024. This sub-analysis descriptively summarizes the responses to 4 survey questions concerning the appropriate definition and treatment options for VC. Results: Of 146 oncologists completing the survey, 96 (66%) worked in an academic setting and 50 (34%) in a community setting. For 96/138 (70%) respondents, ≤5% of patients with HR+/HER2-mBC presented with VC , while 7/138 (5%) respondents reported a rate of > 10%. Among several definitions of VC, 89/145 (61%) respondents chose “severe organ dysfunction, as assessed by signs and symptoms, laboratory studies, and rapid progression of disease,” which is a quote of the ABC5 definition, and 27/145 (19%) chose “liver metastases with liver dysfunction, lymphangitic pulmonary disease with dyspnea, or significant cytopenias due to bone marrow infiltration,” which also aligns with the ABC5 definition. The remainder (29/145; 20%) chose other definitions that did not align with the ABC5 definition. Most respondents (73/137; 53%) identified chemotherapy followed by CDK4/6i + ET maintenance as their preferred treatment for patients with HR+/HER2- mBC with VC. In a separate question, 59/137 (43%) respondents would choose not to use CDK4/6i + ET in patients with VC. Conclusions: Most respondents use the ABC5 definition of VC, but the most preferred treatment option for patients with VC was CDK4/6i + ET as maintenance therapy following chemotherapy, a use which is not approved in the US that indicates a gap between the recommended and real-world use of this regimen. Although the phase 2 RIGHT Choice trial (NCT03839823) showed ribociclib + ET improved PFS and was more tolerable than chemotherapy in patients with investigator-assessed VC, a substantial minority prefer not to use CDK4/6i in patients with VC, demonstrating a need for education on this topic.