A patient-reported outcome measure (PROM) to capture patients' experiences with immuno-oncology therapy (IO)-induced cytokine release syndrome (CRS): The IO-induced CRS patient diary.

11129 Background: IO-inducedCRS has various signs and symptoms that impact different aspects of patients’ lives. While the frequency and severity of IO-induced CRS events underscore the benefit–risk profile and tolerability of IO therapies, patients’ perceptions are critical for measuring the impact of these events on their lives. In this qualitative research study, we developed a novel PROM to track the onset, resolution, and impact of IO-induced CRS events in clinical trials. Methods: Clinician insights and patient interviews were used to identify common IO-induced CRS signs, symptoms, and impacts. Patient-reportable symptoms and impacts were prioritized to form the basis of the IO-induced CRS Patient Diary. The PROM was tested in cognitive debriefing (CD) interviews with 3 clinicians and 3 waves of CD interviews with patients on IO (5 per wave; N = 15). Changes were made to the PROM between each wave to ensure relevance and improve interpretation and usability. Results: After a literature review, qualitative research with 9 clinical experts, and concept-elicitation interviews with 14 patients on IO (3 on CAR-T, 11 on non-CAR-T therapy), 37 patient-reportable signs and symptoms and 7 clinical signs (non–patient reportable) associated with IO-induced CRS were listed. Patients’ concept descriptions and clinicians’ concept priorities were examined, and 12 symptoms and 4 impacts across 5 domains (emotional, physical, social, activities of daily living, and financial) were included in the final diary. The IO-induced CRS Patient Diary—an electronic PROM—has three versions for use at different points in a clinical trial. The “baseline” version is completed before initial IO administration; patients report the incidence and severity of 12 symptoms and their impact on overall health (recall period: the past week). The “day of treatment” version, completed the evening of the treatment day, asks the same questions, plus about symptom manageability (recall period: since receiving the study medication on that day). The “subsequent days” version is the same as the “day of treatment” version, but also asks about impact on regular daily activities, need to rest, and amount of worry caused by CRS (recall period: past 24 hours). It may be completed daily depending on the study design or set of outcomes. Conclusions: The IO-induced CRS Patient Diary, the first of its kind, was developed in line with best practices and is content-valid for the intended use: to capture patients’ experiences with IO-induced CRS events in clinical trials. Understanding these impacts will inform the benefit–risk profile and tolerability of IO therapies. This PROM may also have value in clinical practice, for which additional validation would be needed. Future work will aim to assess its psychometric performance in clinical trials.