Effect of race/ethnicity on clinical outcomes for metastatic colorectal cancer (mCRC) patients in phase 1 trials: A dual institution experience.

3575 Background: Patients with mCRC who progress on standard of care therapies have limited therapeutic options and are associated with poor prognoses. Phase 1 trials are a valuable resource for these patients, offering novel treatment options. However, the appropriate time of consideration for phase 1 trials remains unclear. We sought to analyze the outcomes in a multi-racial cohort of patients with mCRC enrolled in prospective phase I clinical trials to describe clinical characteristics and gauge efficacy of such trials. Methods: We reviewed medical records of patients with mCRC enrolled in phase 1 trials at two institutions from 1999 to 2018 and 2021 to 2024. We collected patient demographics, key clinical characteristics, responses, and deaths. Time on study was calculated as time between first dose of study drug and decision to discontinue study. Overall survival (OS) was calculated as time between the first dose of study drug to date of death or last contact date (censored). Outcomes were analysed by Mantel–Cox test using Prism GraphPad v 10. Results: There were 283 enrollments on 66 phase I trials. Median age (range) was: 59 (29-83) years; non-Hispanic whites (NHW, 126; 44.5%), non-Hispanic blacks (NHB, 69; 24.4%), Hispanic (H, 69; 24.4%), Asian (A, 17; 6.0%), and unknown (UNK, 2; 0.7%). Median number of prior therapies was 3 (range 0-11). ECOG performance status was 0, 1, 2, and unknown, among 62 (21.9%), 181 (63.9%), 11 (3.9%), and 29 (10.2%) patients, respectively. Median number of sites of metastases was 3 (range 0-10). Sites of metastases included liver 77.0%, lung 60.1%, lymph nodes 39.9%, peritoneum 24.4%, bone 20.5%, and brain 1.8%. The primary site of cancer for patients on study was colon (84.1%), followed by rectum (11.7%), rectosigmoid (0.7%), and (simply documented as) CRC (3.5%). The median time on study was 1.8 months for all patients, with NHW 1.9 months, NHB 1.8, H 1.7, A 1.6, and UNK 7.4; p = 0.72. The OS was 8.6 months among all patients, and 7.9, 7.8, 8.8, 9.4, and 9.5 months for NHW, NHB, H, A, and UNK, respectively (p = 0.82). Response evaluable patients were n = 236; including complete response (CR, n = 2, 0.8%), partial response (PR, n = 8, 3.4%), stable disease (SD, n = 80, 33.9%), and clinical benefit rate (CBR = CR+PR+SD, n = 90) 38.1%. Conclusions: Patients with mCRC enrolled onto phase 1 trials showed CBR of 38.1% and OS of 8.6 months, which is comparable to standard third-line therapies that were available during the time period of this study, thus showing promise for their use in clinical practice. No racial/ethnic variation was observed. There was a non-significant trend towards a lower OS with increase in number of prior lines of therapy. A multivariate model will be presented.