Baseline autoimmune diseases and characteristics of solid tumor patients on immune checkpoint inhibitor (ICI) therapy enrolled in a prospective study of immune-related adverse events (irAEs): SWOG S2013 (I-CHECKIT).

2600 Background: I-CHECKIT is a prospective observational study whose primary objective is to develop and independently validate a risk prediction model for the development of Common Terminology Criteria for Adverse Events (CTCAE) Grade 3 or higher non-hematological irAEs in patients with solid tumors during the first year of treatment with ICI. Methods: Any patient initiating ICI per their treating oncologist and National Comprehensive Cancer Network guidelines was eligible to participate in this study. Eligibility criteria were unrestrictive and included participants with active autoimmune disease, decreased performance status, and any stage of cancer. One important exclusion criterion was planned receipt of ICI with chemo, biological or targeted therapy. Hormonal therapy and palliative radiation were allowed. The study is close to accrual in May 2024. Here we describe baseline participant characteristics. Results: Of a total of 2084 enrolled participants, 62 were ineligible. Community based NCORP sites enrolled the majority (n= 1,181, 56%) of participants. Participants were also enrolled from SWOG Latin American sites and Veteran Affairs (VA). 31% (n=656) had skin cancer (melanoma 90%, squamous 5% and Merkel cell 2.9%), 29% (n=604) had lung cancer and 12% (n=256) had kidney cancer. 17% (n=346) received combination ICI. The median age was 69.9 years. 64% were male, 90% (n=1866) were white, 8% (n=165) Hispanic/Latino, 5% (110) black, and 1% (16) Asian. 12% had performance status (PS) 2 or greater. 67% of the participants were overweight or obese. 9% (n=180) of the participants had active autoimmune disease such as rheumatoid arthritis, Type I diabetes, hypothyroidism, psoriasis, Crohn’s, ulcerative colitis. 3% (n=54) had a history of autoimmune disease not currently requiring treatment. Conclusions: The I-CHECKIT observational study enrolled participants representative of a real-world population, as most of the participants were from community practices such as NCORP. Most participants had melanoma, resulting in a higher proportion of white participants. 9% of this population had baseline active autoimmune disease, a population excluded in initial clinical trials, highlighting the broader use of ICI in daily clinical practice. Clinical trial information: NCT04871542 . Baseline characteristics. Age All No (%) Single ICI No (%) Combo ICI No (%) Skin No (%) Lung No (%) 61-65 years 301 (14) 244 (14) 57 (16) 94 (14) 91 (15) 66+ years 1324 (64) 1119 (64) 205 (59) 372 (57) 430 (71) PS 0-1 1822 (88) 1523 (88) 299 (87) 607(93) 500(83) 2 and + 258 (12) 211 (12) 47 (14) 48 (7) 101 (17) Active Autoimmune 180 (9) 153 (9) 27 (8) 54 (8) 51 (8) Hypothyroidism 113 (9) 97 (9) 16 (8) 28 (8) 34 (8) Type I Diabetes 15 (1) 10 (1) 5 (1) 5 (1) 4 (1) Psoriasis 11 (1) 9 (1) 2 (1) 3 (0) 3 (0)