Disparity of treatment-related adverse events and outcome in patients with early-onset metastatic colorectal cancer (mCRC).

Abstract

6560 Background: While the incidence of newly diagnosed early-onset mCRC has been increasing, disparity of treatment-related adverse events (AE) and outcomes of this patient population has been inadequately studied with inconclusive findings. We aimed to evaluate such age-related disparity and explore potential underlying causes. Methods: We used individual patient data from 3 clinical trials in Project Data Sphere where 756 and 467 patients with mCRC received first-line FOLFOX in study 1 (NCT 00305188, NCT00272051) and study 2 (NCT00364013), respectively. Clinical NGS data of 763 patients with mCRC from prospectively maintained Moffitt Clinical Genomics Database were used to assess genomic alterations. Patients were categorized into 3 age groups: <50, 50-65, and >65 years. Continuous and categorical variables were compared with t test and χ2 test, respectively. Kaplan-Meier method and log-rank test were used for survival analysis. Benjamini-Hochberg procedure was used to adjust for multiple comparisons. Results: Among 1986 patients included, 341 (17.2%) in the <50 group, 912 (45.9%) in the 50-65 group, 733 (36.9%) in the >65 group had similar baseline characteristics. Outcomes: Patients in the <50 group had shorter median OS compared to the 50-65 (15.5 vs 20.5 month, p=0.003) and >65 groups (15.5 vs 20.8 months, p=0.004) and shorter median PFS compared to the 50-65 (8.1 vs 9.4 month, p=0.039) and >65 groups (8.1 vs 8.6 months, p=0.07) in study 1. Findings were confirmed in study 2. Toxicity: Compared to other age groups, the <50 group had a higher incidence of severe (grade≥3) abdominal pain (8.4% vs 3.4%, p=0.01), severe anemia (6.1% vs 1.2%, p=0.001), nausea/vomiting (69.3% vs 58.8%, p=0.02), but lower incidence of severe diarrhea (6.1% vs 10.8%, p=0.02), severe neutropenia (25.7% vs 44.2%, p<0.001), and severe fatigue (4.5% vs 7.3%, p=0.02). The <50 group had earlier onset of nausea/vomiting (1.0 vs 2.3 weeks, p=0.01), mucositis (3.6 vs 5.4 weeks, p=0.05), and neutropenia (8.0 vs 9.0 weeks, p=0.04), and shorter duration of mucositis (0.6 vs 0.9 weeks, p=0.006). Outcomes + toxicity: In the <50 group, abdominal pain was associated with worse OS (HR 1.6, p=0.01). In contrast, fatigue (HR 0.66, p=0.03) and mucositis (HR 0.67, p=0.046) were associated with better OS. Neuropathy was associated with better PFS (HR 0.61, p=0.009). Genomics: Our NGS data showed that the <50 group had more ERBB2 amplification (10.5% vs 4.0%, p=0.04) and a trend of more TP53 mutations (80.2% vs 72.0%, p=0.07). These findings were confirmed in an independent mCRC cohort (n=471, MSK, Gastroenterology 2020). Conclusions: Patients with early-onset mCRC had worse outcome and unique treatment-related AE patterns. Distinct genomic profiles could explain some of the disparities. Our findings might improve a personalized management approach in patient selection for chemotherapy, counseling and AE monitoring.