Outcomes of patients (pts) with metastatic colorectal cancer (mCRC) participating in phase I clinical trials: The Sarah Cannon Research Institute UK experience.

142 Background: In the last decade immunotherapy, BRAF inhibitors (inh) and trifluridine-tipiracil became new standard of care (SoC) options for selected mCRC pts through the drug development pathway. In this study we aimed to evaluate clinical characteristics and outcomes of pts with mCRC participating in phase I trials. Methods: Electronic medical records from 10/2011 to 07/2022 were reviewed; pts who received at least one dose of trial drug were included. Data were analysed with descriptive statistic. Results: 81 (100%) pts were identified; 38 (47%) female; median age: 59 (range 31-80); 31 pts (38%) - right sided; 35 (44%) - RASmut, 29 (36%) - BRAFmut, 16 (20%) - RAS/BRAFw; MSI-H status was detected in 11 pts. Eleven pts participated in >1 trial, for a total of 96 cases. Median follow-up was 7 months (m); overall response rate was 6.8%, mPFS: 2.9 m, mOS 18.8 m. Age<50 (P=0,02), low lymphocyte/monocyte ratio (LMR ≤2.8) (P=0.02), in-situ primary tumour (P<0.001), no adjuvant therapy (P=0,001), right sided tumour (P=0,02) were independently associated with shorter OS (univariate analysis); the last three variables remained significant in multivariate analysis. Outcomes according to 4 drug classes and others (chemotherapy-based +/- targeted agents) are shown. Conclusions: Phase 1 trials offer a reasonable therapeutic approach for pts with mCRC and early access to drugs with potential to become SoC in future. [Table: see text]