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3575 Background: Pts with mCRC frequently receive ≥1 sequential treatment TL. Approximately 50%-60% of pts receive second-line (L2) and 20%-30% third-line (L3) regimens in routine practice. We investigated the pts clinical/tumor characteristics and their prognostic impact across TL. Methods: Data from 37,560 pts enrolled in 48 randomized trials (34 in first (L1), 9 in L2, and 5 in L3) were analyzed. Candidate variables (VAR) measured at enrollment were sex, age, body mass index, performance status (PS), bilirubin, hemoglobin (Hb), platelets (Pl), derived white blood cells-to-absolute neutrophil counts ratio (WBC/ANC), lactate dehydrogenase (LDH), alkaline phosphatase (ALP), primary tumor location, and number and location of metastatic sites (MS). Missing data were imputed. VAR with significant value at all TL were selected to construct a prognostic score of overall survival (OS) in training set (TS, n=30,050; 80%). For each TL, the score was calculated as the sum on the estimations of the VAR’ coefficients from the common multivariate model; Cox’s model was used to define risk groups. The discrimination capability was assessed using the Harrell’s C-index. External validation was done in the validation set (VS, n=7,510; 20%). Results: A total of 26,974 pts in L1, 7,693 pts in L2 and 2,893 pts in L3 were analyzed. The following characteristics increased continuously over TL: ≥2 MS (57%, 72%, 82%), lung metastases (50%, 74%, 91%), lymph nodes metastases (51%, 61%, 80%), KRAS mutation (37%, 47%, 51%) and elevated ALP (46%, 52%, 61%). BRAF mutation decreased (9%, 7%, 5%). In L1 vs L3 trials, 70% vs 89% of patients had primary tumor resection, 10% vs 80% had at least one metastasectomy and 31% vs 78% had a late metachronous (>12 months) metastasis. 7 independent VAR were retained in the prognostic score (PS, Hb, Pl, WBC/ANC, LDH, ALP, and the number of MS); four pt groups with significantly different prognoses were defined (table). This score remained valid when excluding pts with PS 2. Third-line oral drugs (vs placebo) and subsequent line (L2/L1 or L3/L2) were effective in all prognostic groups. Conclusions: Clinical/tumor pt characteristics significantly varied over subsequent TL in patients included in randomized trials. The same prognostic model using practical clinical and biological variables can be used in all TL.[Table: see text]

Abstract Background Unplanned subgroup analyses from several studies have suggested primary tumor sidedness (PTS) as a potential prognostic and predictive parameter in metastatic colorectal cancer (mCRC). We aimed to investigate the impact of PTS on outcomes of mCRC patients. Methods PTS data of 9277 mCRC patients from 12 first-line randomized trials in the ARCAD database were pooled. Overall survival (OS) and progression-free survival (PFS) were assessed using Kaplan-Meier and Cox models adjusting for age, sex, performance status, prior radiation/chemotherapy, and stratified by treatment arm. Predictive value was tested by interaction term between PTS and treatment (cetuximab plus chemotherapy vs chemotherapy alone). All statistical tests were 2-sided. Results Compared with right-sided metastatic colorectal cancer patients (n = 2421, 26.1%), left-sided metastatic colorectal cancer patients (n = 6856, 73.9%) had better OS (median = 21.6 vs 15.9 months; adjusted hazard ratio [HRadj] = 0.71, 95% confidence interval [CI] = 0.67 to 0.76; P < .001) and PFS (median = 8.6 vs 7.5 months; HRadj = 0.80, 95% CI = 0.75 to 0.84; P < .001). Interaction between PTS and KRAS mutation was statistically significant (Pinteraction < .001); left-sidedness was associated with better prognosis among KRAS wild-type (WT) (OS HRadj = 0.59, 95% CI = 0.53 to 0.66; PFS HRadj =0.68, 95% CI = 0.61 to 0.75) but not among KRAS mutated tumors. Among KRAS-WT tumors, survival benefit from anti-EGFR was confirmed for left-sidedness (OS HRadj = 0.85, 95% CI = 0.75 to 0.97; P = .01; PFS HRadj = 0.77, 95% CI = 0.67 to 0.88; P < .001) but not for right-sidedness. Conclusions The prognostic value of PTS is restricted to the KRAS-WT population. PTS is predictive of anti-EGFR efficacy, with a statistically significant improvement of survival for left-sidedness mCRC patients. These results suggest treatment choice in mCRC should be based on both PTS and KRAS status.

Abstract Background First-line therapeutic strategies for patients with BRAFV600E-mutated (BRAFmt) metastatic colorectal cancer (mCRC) mainly rely on subgroup analyses from randomized controlled trials (RCTs). We aimed to assess the prognostic and predictive impact of BRAFmt on the efficacy of targeted therapies with first-line chemotherapy. Methods Individual patient data from first-line RCTs with BRAF and KRAS status data in the ARCAD database were pooled. Progression-free survival and overall survival (OS) were assessed using Kaplan-Meier and Cox models. Outcomes were compared between treatment groups that were concurrently randomly assigned whenever possible. Results A total of 6391 patients from 10 RCTs were included: 573 BRAFmt (9.0%), 2059 KRASmt (32.2%), and 3759 double wild type (58.8%). BRAFmt mCRC patients experienced statistically significantly poorer OS than those with KRASmt (adjusted hazard ratio [HRadj] = 1.46, 95% confidence interval [CI] = 1.30 to 1.64) and patients with double wild-type tumors (HRadj = 2.14, 95% CI = 1.94 to 2.36). Anti-EGFR agents did not improve progression-free survival or OS of BRAFmt mCRC patients, based on 4 RCTs testing chemotherapy with or without anti-epidermal growth factor receptor (anti-EGFR) (HRadj = 0.96, 95% CI = 0.71 to 1.30; and HRadj = 0.85, 95% CI = 0.66 to 1.14, respectively). Conclusions Our data suggest that the addition of anti-EGFR agents to chemotherapy is ineffective as first-line treatment for BRAFmt mCRC patients.

108 Background: Primary tumor sidedness has emerged as a prognostic and predictive biomarker for patients (pts) with metastatic colorectal cancer (mCRC). Tumor bulk has also been postulated to predict response to anti-EGFR therapy. We sought to evaluate the role of tumor bulk as a predictive biomarker to anti-EGFR therapy in pts with left- (LS) and right-sided (RS) mCRC. Methods: Data from 476 pts with mCRC enrolled across 2 first-line trials of anti-EGFR plus chemotherapy versus chemotherapy were pooled. Pts were included if there was available information on tumor sidedness and tumor bulk. All were KRAS wild-type and BRAF wild-type or unknown BRAF status. The right colon was defined as the cecum through the transverse colon, and the left colon as the splenic flexure through the rectum. Tumor bulk was the mean tumor size of target lesions at baseline, bulky defined as > 3.5 cm. Overall survival (OS) and progression-free survival (PFS) were assessed using Kaplan-Meier and Cox models adjusting for performance status (PS), platelet count, primary tumor (PT) resection, number of metastatic sites, and stratified by study. Results: Pts with bulky tumors (211, 44%) had higher PS, white blood cell and platelet counts, higher CEA, fewer sites of metastatic disease, more liver than lung metastases, and fewer had PT resection. OS and PFS medians in months (mos) are presented in the table with 95% confidence intervals (95%CIs). Bulky tumors had inferior median OS compared with non-bulky (mOS, 17.9 vs. 21.3 mos, HRadj 1.33, 95% CI 1.05-1.69, P = 0.016) although median PFS was similar (mPFS, 8.6 vs. 8.7 mos, HRadj 1.15, 95% CI 0.92-1.42, P = 0.21). Conclusions: Tumor bulk is an independent prognostic factor for OS in KRAS wild-type and BRAF wild-type or unknown BRAF status pts. Pts with non-bulky RS tumors have survival outcomes similar to pts with bulky LS tumors. Although the mPFS for pts with RS tumors treated with anti-EGFR therapy was the lowest across subgroups, this finding was not statistically significant. Further research is warranted into whether pts with bulky RS tumors benefit from anti-EGFR therapy. Clinical trial information: NCT00182715, NCT00640081. [Table: see text]

PURPOSE: In patients with stage III colon cancer (CC) whose tumors demonstrate microsatellite instability (MSI), the efficacy of adjuvant fluoropyrimidine (FP) with or without oxaliplatin has not been clearly demonstrated and the prognostic value of MSI remains uncertain. MATERIALS AND METHODS: Individual patient data from the ACCENT database were used to evaluate the effect of FP with or without oxaliplatin on disease-free survival (DFS) and overall survival (OS) among patients with MSI stage III CC and the prognostic value of MSI in patients treated with FP plus oxaliplatin, by stratified Cox models adjusted for demographic and clinicopathological factors. RESULTS: MSI status was available for 5,457 patients (609 MSI, 11.2%; 4848 microsatellite stable [MSS], 88.8%) from 12 randomized clinical trials (RCTs). Oxaliplatin significantly improved OS of MSI patients from the two RCTs testing FP with or without oxaliplatin (n = 185; adjusted hazard ratio [aHR] = 0.52, 95% CI, 0.28 to 0.93). Among the 4,250 patients treated with FP plus oxaliplatin (461 MSI and 3789 MSS), MSI was associated with better OS in the N1 group compared with MSS (aHR = 0.66; 95% CI, 0.46 to 0.95) but similar survival in the N2 population (aHR = 1.13; 95% CI, 0.86 to 1.48; P interaction = .029). The main independent prognosticators of MSI patients treated with FP plus oxaliplatin were T stage (aHR = 2.09; 95% CI, 1.29 to 3.38) and N stage (aHR = 3.57; 95% CI, 2.32 to 5.48). Similar results were observed for DFS in all analyses. CONCLUSION: Adding oxaliplatin to FP improves OS and DFS in patients with MSI stage III CC. Compared with MSS, MSI patients experienced better outcomes in the N1 group but similar survival in the N2 group.

Background Current adverse event reporting practices do not document longitudinal characteristics of adverse effects, and alternative methods are not easily interpretable and have not been employed by clinical trials. Introducing time parameters in the evaluation of safety that are comprehensive yet easily interpretable could allow for a better understanding of treatment quality. In this study, we developed and applied a novel adverse event reporting method based on longitudinal adverse event changes to aid describing, summarizing, and presenting adverse event profile. We termed it the “Adverse Event Load, Onset, and Maximum Grade” method. Methods We developed two adverse event summary metrics to complement the traditional maximum grade report. Onset time indicates the time period in which the maximum grade for a specific adverse event occurred and was defined as “early” (i.e. maximum grade happened for the first time before 6 weeks) or “late” (i.e. after the 6 th week). Adverse event load indicates the overall severity of a specific adverse event over the entire treatment. Higher adverse event load indicates a worse overall experience. These metrics can be calculated for adverse events with different maximum grades, in treatments with planned changes (e.g. dosage changes), using data sets with different number of adverse event data points between treatments (e.g. treatments with longer cycle lengths may have less adverse event data points) and on data sets with different adverse event data availability (e.g. cycle basis and patient-outcome reports). We tested the utility of this method using individual patient data from two major backbone therapies (“Irinotecan” and “Oxaliplatin”) from the N9741 trial available in the Fondation ARCAD database ( fondationarcad.org ). We investigated profiles of diarrhea, neutropenia/leukopenia, and nausea/vomiting. Results Our method provided additional information compared to traditional adverse event reports. For example, for nausea/vomiting, while patients in Irinotecan had a higher risk of experiencing maximum grade 3–4 (15.6% vs 7.6%, respectively; p < 0.001), patients in both groups experienced similar severity over time (adverse effect load = 0.102 and 0.096, respectively; p = 0.26), suggesting that patients in Oxaliplatin experienced a lower-grade but more persistent nausea/vomiting. For neutropenia/leukopenia, more patients in Irinotecan experienced their maximum grade for the first time early in the treatment compared to patients in Oxaliplatin (67.9% vs 41.7%; p < 0.001), regardless of maximum grade. Longitudinal information can help compare treatments or guide clinicians on choosing appropriate interventions for low-grade but persistent adverse event or early adverse event onset. Conclusion We developed an adverse event reporting method that provides clinically relevant information about treatment toxicity by incorporating two longitudinal adverse event metrics to the traditional maximum grade approach. Future research should establish clinical benchmarks for metrics included in this adverse event reporting method.

Abstract Background Adjuvant chemotherapy is a standard treatment option for patients with stage III and high-risk stage II colon cancer. Sex is one of several factors responsible for the wide inter-patient variability in drug responses. Amalgamated data on the effect of sex on the toxicity of current standard adjuvant treatment for colorectal cancer are missing. Methods The objective of our study was to compare incidence and severity of major toxicities of fluoropyrimidine- (5FU or capecitabine) based adjuvant chemotherapy, with or without oxaliplatin, between male and female patients after curative surgery for colon cancer. Adult patients enrolled in 27 relevant randomized trials included in the ACCENT (Adjuvant Colon Cancer End Points) database, a large, multi-group, international data repository containing individual patient data, were included. Comparisons were conducted using logistic regression models (stratified by study and treatment arm) within each type of adjuvant chemotherapy (5FU, FOLFOX, capecitabine, CAPOX, and FOLFIRI). The following major toxicities were compared (grade III or IV and grade I-IV, according to National Cancer Institute Common Terminology Criteria [NCI-CTC] criteria, regardless of attribution): nausea, vomiting, nausea or vomiting, stomatitis, diarrhea, leukopenia, neutropenia, thrombocytopenia, anemia, and neuropathy (in patients treated with oxaliplatin). Results Data from 34 640 patients were analyzed. Statistically significant and clinically relevant differences in the occurrence of grade III or IV nonhematological {especially nausea (5FU: odds ratio [OR] = 2.33, 95% confidence interval [CI] = 1.90 to 2.87, P &lt; .001; FOLFOX: OR = 2.34, 95% CI = 1.76 to 3.11, P &lt; .001), vomiting (5FU: OR = 2.38, 95% CI = 1.86 to 3.04, P &lt; .001; FOLFOX: OR = 2.00, 95% CI = 1.50 to 2.66, P &lt; .001; CAPOX: OR = 2.32, 95% CI = 1.55 to 3.46, P &lt; .001), and diarrhea (5FU: OR = 1.35, 95% CI = 1.21 to 1.51, P &lt; .001; FOLFOX: OR = 1.60, 95% CI = 1.35 to 1.90, P &lt; .001; FOLFIRI: OR = 1.57, 95% CI = 1.25 to 1.97, P &lt; .001)} as well as hematological toxicities (neutropenia [5FU: OR = 1.55, 95% CI = 1.37 to 1.76, P &lt; .001; FOLFOX: OR = 1.96, 95% CI = 1.71 to 2.25, P &lt; .001; FOLFIRI: OR = 2.01, 95% CI = 1.66 to 2.43, P &lt; .001; capecitabine: OR = 4.07, 95% CI = 1.84 to 8.99, P &lt; .001] and leukopenia [5FU: OR = 1.74, 95% CI = 1.40 to 2.17, P &lt; .001; FOLFIRI: OR = 1.75, 95% CI = 1.28 to 2.40, P &lt; .001]) were observed, with women being consistently at increased risk. Conclusions Our analysis confirms that women with colon cancer receiving adjuvant fluoropyrimidine-based chemotherapy are at increased risk of toxicity. Given the known sex differences in fluoropyrimidine pharmacokinetics, sex-specific dosing of fluoropyrimidines warrants further investigation.

7009 Background: Survival outcomes of 2nd line mCRC therapy for OA are poorly understood. We evaluated the rates and survival outcomes of 2nd line therapy among OA age 70+ compared to younger adults (YA) age < 70 following progression on 1st line clinical trials. Methods: Associations between clinical characteristics of pts with available treatment data after progression on 10 of 23 1st line ARCAD trials, time to initial progression (TTiP) and 2nd line therapy were evaluated. Time to progression (TTP) and overall survival (OS) were compared between OA and YA enrolled on 2nd line trials by Cox regression, adjusting for age, sex, ECOG PS, number of metastatic sites, presence of metastasis in lung/liver/peritoneum. Results: Sixteen percent of 1st line ARCAD trial participants were age 70+ (n = 870). Data for 2nd line therapy was available for 60.6% pts (3206/5289). Each additional decade of life was associated with 11% lower odds of receiving 2nd line therapy in multivariate analysis (p = 0.0117). OA participating in 2nd line trials (7.9% age 75+ of 7921) experience similar TTP and OS to YA (mTTP: 5.1 vs. 5.2mos; mOS 11.6 vs 12.4mos, respectively). Conclusions: We did not observe a statistical difference in survival outcomes by age following 2nd line mCRC therapy. Further study is needed to examine unmeasured comorbidity and use of geriatric assessment to select OA likely to benefit from 2nd line therapy. [Table: see text]

4099 Background: Colorectal cancer (CRC) incidence and mortality has decreased since the 1970s but the incidence is increasing in young adults (age 20-49). The incidence of early onset CRC (eoCRC) will keep increasing significantly based on the trends of the SEER CRC registry data. There is limited data suggesting eoCRC may have different behaviors compared to traditional CRC (tCRC, age ≥ 50). Methods: Individual pt data of 47184 stage II/III CRC pts from 25 randomized studies in the ACCENT database were pooled. The distributions of demographics, clinicopathological features, biomarker status, and treatment-related data were summarized by age group. Overall survival (OS), disease-free survival (DFS), recurrence-free rate (RFR), and survival after recurrence (SAR) were assessed by Kaplan-Meier curves and Cox models stratified by treatment arms within studies, adjusting for stage, performance status (PS), BMI and grade. Results: Using 5% difference between age groups as clinically meaningful cutoff, eoCRC had similar gender, race, ethnicity, PS, risk group, disease sidedness and T stage as tCRC. eoCRC were less likely overweight (30 vs 36%) and more pts had ≥ 12 lymph nodes resected (63 vs 51%). eoCRC had more frequent dMMR status (18 vs 12%), less BRAF mutations (5 vs 13%), and more dMMR/BRAF wild type (WT) status (17 vs 7%). Overall, eoCRC had better OS, DFS, and SAR, with the most significant differences between the < 30 and > = 70 age groups. Similar results were observed within pMMR pts. eoCRC experienced less hematological side effects, diarrhea, and stomatitis, but had more nausea and/or vomiting. Conclusions: eoCRC have unique characteristics; although statistically significant, the clinical differences in outcomes between eoCRC and tCRC are potentially due to the difference seen in extremely young and old pts. eoCRC have a different adverse events panel compared to tCRC. [Table: see text]

4090 Background: EGFR mAbs have become incorporated into clinical practice for the management of mCRC over the last decade. KRAS and NRAS mutations are used as predictive biomarkers and BRAF V600E mutations are associated with an adverse prognosis. The observed TE within biomarker subpopulations has varied between studies. Methods: IPD from randomized trials with head-to-head comparison between EGFR mAb versus no EGFR mAb (chemotherapy alone or BSC) in mCRC, across all lines of therapy (first, second and later), were pooled. Biomarker subpopulations are defined in the table. Overall survival (OS) and progression-free survival (PFS) were compared between groups by Cox model, stratified by studies and adjusted by age, gender, and performance status. TEs were estimated by adjusted hazard ratio (HRadj) and 95% confidence interval (CI). Within each biomarker subgroup, EGFR mAb efficacy was explored according to multiple exploratory factors, including line of therapy, type of backbone chemo, gender, sidedness and site of metastasis. Interaction tests were performed. P-values < 0.01 were considered statistically significant to account for multiple comparisons. Results: 5729 pts from 8 studies with data available for ≥ 1 biomarker were analysed. PFS benefits (median 9.2 mos in EGFR mAbs, 8.0 mos in no EGFR mAbs) were confirmed in triple-WT pts, but not for OS (refer to table). No OS/PFS benefits were observed for pts with any of the MT tumors. Exploratory analyses showed a potential detrimental TE of EGFR mAbs in KRAS MT mCRC with liver metastasis (OS: HRadj 1.22, p = .003, pinteraction .0056; PFS: HRadj 1.24, p = .0009, pinteraction .0008). These results were confirmed within the subgroup of pts with all 3 biomarkers available. Conclusions: This is the largest IPD analysis to explore the predictive value of RAS/BRAF biomarkers in mCRC. Our findings demonstrate that there is no evidence of efficacy of EGFR mAbs in KRAS, BRAF and/or NRAS MT mCRC. EGFR mAbs might have a detrimental effect in KRAS MT mCRC with liver metastases. [Table: see text]