Real-world clinical efficacy of epidermal growth factor receptor inhibitors (EGFRi) in patients with early-onset (eo), metastatic colorectal cancer (mCRC).

Abstract

36 Background: The incidence of eo CRC (age of onset: <50 years) is rising globally, although specific reasons remain unknown. In a prior study using the ARCAD database, the addition of EGFRi to chemotherapy (chemo) significantly improved progression-free survival (PFS) in late-onset (lo) KRAS wild-type (wt) left-sided mCRC patients (pts); however, no such effect was observed in eo mCRC pts (Jin Z et al., 2022). Methods: This retrospective study used the nationwide Flatiron Health electronic health record-derived de-identified database of adult patients diagnosed with mCRC on/after January 1, 2013 with data cut-off on June 30, 2023. The cohort included pts with RAS/BRAF wt and left-sided primary tumors who were treated with first-line (1L) chemo+EGFRi, chemo+bevacizumab (bev), or chemo alone. Associations of disease onset and 1L therapy with real-world overall survival and time to next treatment (rwOS, rwTTNT) were assessed using Kaplan-Meier methods and hazard models adjusted for clinical confounders including year of metastatic diagnosis, group stage at initial diagnosis, site of disease, gender, race/ethnicity, and ECOG performance status. Results: Among 895 left-sided RAS/BRAF wt mCRC pts, 216 and 679 pts had eo and lo mCRC, respectively. In pts treated with chemo+EGFRi vs chemo alone, the adjusted hazard ratio (HR) (95% CI) of rwTTNT was 0.93 (0.56-1.53) and 0.77 (0.58-1.02) for eo and lo pts, respectively; the adjusted HR (95% CI) of rwOS was 0.96 (0.51-1.83) and 0.78 (0.57-1.07) in eo and lo pts, respectively. In pts treated with chemo+bev vs chemo alone, the adjusted HR (95% CI) of rwTTNT was 1.00 (0.62-1.60) and 0.75 (0.58-0.97) for eo and lo pts, respectively; the adjusted HR (95% CI) of rwOS was 0.97 (0.54-1.75) and 0.78 (0.58-1.03) in eo and lo pts, respectively. Conclusions: Adding EGFRi to chemotherapy suggested potential improvements in rwTTNT and rwOS in lo pts but not in eo pts, similar to findings from the prior ARCAD database study. Such differences in outcomes, similarly observed in pts treated with chemo+bev, underscore the need for tailored therapeutic strategies. Given the wide confidence intervals in this study, future research with larger patient cohorts or longer follow-up may yield more precise estimates of these differences. [Table: see text]