EMB-01, a tetravalent anti-EGFR/cMET bispecific antibody, in the left-sided, RAS/BRAF wild-type, late-line metastatic colorectal cancer: Subgroup analysis of baseline characteristics and response from a phase 1/2 study.

118 Background: Left-sided RAS/BRAF wild-type metastatic colorectal cancer (mCRC) is sensitive to anti-EGFR containing regimens, however, the impact of clinicopathological features on treatment outcomes in this subgroup remains unclear. This analysis aimed to identify factors associated with EMB-01 response. Methods: In this exploratory baseline characteristics/response subgroup analysis, all patients with left-sided, RAS/BRAF wild-type mCRC and no prior fruquintinib/regorafenib/TAS-102 (favorable group) were selected from a Phase 1/2 study (NCT05176665). Baseline variables—including metastatic status, prior therapies, time from diagnosis, and genomic alterations identified via ctDNA- were collected at screening. Response was assessed by investigators per RECIST v1.1 every 6 weeks. Retrospective correlations between these factors and treatment outcomes were evaluated. Results: As of Jun 9, 2025, 29 response-evaluable mCRC patients with favorable features were included in the analysis. Median prior lines were 3, and ORR was 24.1%. Among them, 22 patients aged