Hecht, J. Randolph

101 Background: Colorectal cancer (CRC) incidence and mortality have decreased since the 1970s, but the incidence in young adults (20-49 years, named early-onset CRC, eoCRC) has been increasing. eoCRC patients with metastatic disease are treated with the same standard regimens as late-onset CRC (loCRC, age ≥ 50 years) although detailed response data for eoCRC are largely missing. Methods: Individual patient data on 7,604 subjects with metastatic eoCRC from 11 first line randomized bevacizumab studies between 2000 and 2012 in the ARCAD advanced colorectal cancer database were pooled. The distributions of demographics, clinicopathological features, biomarkers, and outcome data were summarized by age groups. Progression-free survival (PFS) and overall survival (OS) were assessed by Kaplan-Meier curves and Cox models stratified by treatment arms within studies, adjusting for potential confounders. Predictive value of age group was evaluated by testing interaction effect between treatment and age variables. Results: Female eoCRC are more commonly seen compared to loCRC (46.8% vs. 38.7%, p<0.0001). Patients with eoCRC (n=1,289) were significantly more likely to have had prior metastasectomy (17.5% vs. 13.5%, p=0.043) and lung metastatic disease (67% vs. 59.8%, p<0.001), but less likely to have distant lymph node metastatic disease (58.8 vs. 62.9%, p=0.036) or KRAS mutation (29.2% vs. 34.4%, p=0.042) compared to those with loCRC (n=6,315). eoCRC and loCRC patients had similar distributions according to PS, primary tumor sidedness, prior primary tumor resection, liver involvement, peritoneal involvement, number of metastatic sites, NRAS and BRAF. Age of disease onset was not a statistically significant prognostic factor for PFS in univariate and multivariate analysis (seen in table). Bevacizumab in addition to chemo improved PFS in eoCRC population (9.9 vs. 6.8 months, HR = 0.66, p<0.001), which was similar to the findings in loCRC population (9.4 vs. 7.3 months, HR= 0.73, p<0.001, interaction p=0.54). By multivariate analysis, a greater improvement in PFS was noted for the addition of bevacizumab in eoCRC relative to LoCRC patients (HR = 0.62 vs. HR = 0.82). Conclusions: Treatment naive eoCRC patients with metastatic disease derive similar benefit from bevacizumab relative to their average age counterparts.[Table: see text]

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]

This selection from the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for Colon Cancer focuses on systemic therapy options for the treatment of metastatic colorectal cancer (mCRC), because important updates have recently been made to this section. These updates include recommendations for first-line use of checkpoint inhibitors for mCRC, that is deficient mismatch repair/microsatellite instability-high, recommendations related to the use of biosimilars, and expanded recommendations for biomarker testing. The systemic therapy recommendations now include targeted therapy options for patients with mCRC that is HER2-amplified, or BRAF V600E mutation–positive. Treatment and management of nonmetastatic or resectable/ablatable metastatic disease are discussed in the complete version of the NCCN Guidelines for Colon Cancer available at NCCN.org . Additional topics covered in the complete version include risk assessment, staging, pathology, posttreatment surveillance, and survivorship.

4054 Background: In treatment trials of patients with metastatic colorectal cancer (mCRC), KRAS mutation status of tumor samples has been retrospectively demonstrated to be predictive of treatment benefit. Historically, clinical trials have not required tissue samples to be tested for KRAS mutation status as a condition of enrollment. Therefore, KRAS analyses have been based on available tissue samples representing only a portion of patients retrospectively analyzed for KRAS status and correlated with treatment end- points. Methods: A weighted analysis of pooled data was performed using six recently presented or published clinical trials of targeted therapy in mCRC which tested for the association of KRAS status with Progression Free Survival (PFS). The goal of the analysis was to determine whether there is a significant difference in PFS between the intention to treat (ITT) population and KRAS population in both the treatment and control arms. Results: The total ITT population of the pooled studies is 3864, and for the total KRAS population, 2295; a 59.4% retrieval rate (range 28–92%) for tissue samples available for KRAS analysis. The weighted Δ PFS across all arms between the ITT population and the KRAS population was 0.2 months with a range of 0–0.7 months. Of the 12 subgroups (6 control and 6 treatment arms), five had no difference in PFS between ITT and KRAS evaluable populations at all, and two additional subgroups demonstrated a difference PFS of only 0.1 months. The two studies with the lowest tissue retrieval rates (28% and 45%) had the largest Δ PFS. Conclusions: There is no meaningful difference in the PFS between the ITT and KRAS populations based on our analysis of pooled data. The difference in PFS was greatest in the two studies with the lowest rate of retrieval of tissue samples for KRAS testing. As such, subgroup analysis is better able to estimate and reflect the ITT population if a higher percentage of samples is able to be obtained. Further, our results suggest that there is not an inherent systemic bias influencing any potentially observed differences in PFS. Tissue samples should be required for all patients entering a clinical trial to avoid this issue and to make retrospective analysis more valid. [Table: see text]

4029 Background: The clearance of 5-FU differs significantly between men (M) and women (W). Adjuvant chemotherapy (CT) for CRC has a higher toxicity in W. The impact of sex on efficacy and toxicity in first-line trials of metastatic CRC (mCRC) is unknown. Methods: We analyzed patient (pt) and tumor characteristics, toxicities (nausea (AE1), vomiting (AE2), diarrhea, neutropenia (AE3)) and efficacy (overall survival (OS), progression-free survival (PFS)) according to sex in the following treatment groups: A: CT alone, B: CT + bevacizumab, C: CT + EGFR-antibodies, with subgroup analyses in the CT alone group for single-agent, doublets and triplets, as well as irinotecan- and oxaliplatin-based regimens. Pts from trials with treatments still used today and all relevant data available were eligible. OS and PFS were assessed using Kaplan-Meier and Cox models adjusted for primary tumor location and performance status (PS). Results: We included 28 trials with 18.399 pts (11.352 M and 7.047 W). W were younger (61 vs. 63 years), had more often a PS of 1 (49 vs 45%), BRAF mutations (10 vs. 7%), right-sided tumors (42 vs. 35%) and less often rectal tumors (26 vs. 32%). Significant differences in toxicity are reported in table. Rates of diarrhea were similar. There was no sex disparity in OS in the predefined subgroups except for pts receiving triplets where OS was better in M (HRadj=1.39 (1.05 - 1.85)). Median (interquartile range) OS in months for M and W was 16.7 (9.2-27.4) and 16.2 (8.9-27.2) in group 1, 21.9 (12.7-37.5) and 22.3 (12.9 – 39.0) in group 2, and 26.8 (14.6-45.3) and 24.8 (12.3-49.2) in group 3. HRsadj (W vs M) (95% CI), p values for OS were 1.02 (0.96-1.09), .557, 0.92 (0.83-1.03), .142, 0.99 (0.85-1.14), .866. Conclusions: M and W with mCRC differ significantly regarding patient and tumor characteristics. The significant higher toxicity in W does not translate in a higher treatment efficacy. Apart from known sex differences in pharmacokinetics of 5-FU, differences in pharmacodynamics must be postulated. [Table: see text]

Abstract Background Carcinoembryonic antigen (CEA) levels are used in conjunction with imaging to monitor response to systemic therapy in metastatic colorectal cancer (mCRC). We sought to identify a threshold for CEA change from baseline to predict progressive disease (PD) in mCRC patients receiving first-line therapy. Methods Patients from trials collected in the ARCAD database were included if baseline CEA was at least 10 ng/mL and repeat CEA was available within 14 days of first restaging scan. Optimal cutoffs for CEA change were identified by receiver operating characteristic analysis. Prediction performance of cutoffs was evaluated by sensitivity, specificity, and negative predictive value. Analyses were conducted by treatment class: chemotherapy alone, chemotherapy with anti-VEGF antibody, and chemotherapy with anti-EGFR antibody. Results A total of 2643 mCRC patients treated with systemic therapy were included. Median percent change of CEA from baseline to first restaging for patients with complete response, partial response, or stable disease (non-PD) and PD was −53.1% and +23.6% for chemotherapy alone (n = 957) and −71.7% and −45.3% for chemotherapy with anti-VEGF antibody (n = 1355). The optimal area under the curve cutoff for differentiating PD from non-PD on first restaging was −7.5% for chemotherapy alone and −62.0% for chemotherapy with anti-VEGF antibody; chemotherapy alone, adjusted odds ratio = 6.51 (95% CI = 3.31 to 12.83, P &lt; .001), chemotherapy with anti-VEGF antibody, adjusted odds ratio = 3.45 (95% CI = 1.93 to 6.18, P &lt; .001). A 99% negative predictive value clinical cutoff for prediction of non-PD would avoid CT scan at first restaging in 21.0% of chemotherapy alone and 16.2% of chemotherapy with anti-VEGF antibody–treated patients. Among patients with stable disease on first restaging, those with decreased CEA from baseline had statistically significantly improved progression-free and overall survival. Conclusions Change in CEA from baseline to first restaging can accurately predict non-progression and correlates with long-term outcomes in patients receiving systemic chemotherapy.

3533 Background: PFS has previously been established as a surrogate for OS based on IPD from first-line mCRC trials conducted before 1999. As mCRC treatment (trt) has advanced in the last decade and OS has increased from 1 to 2 years, this surrogacy required re-examination. Methods: IPD from 16,762 pts, median age 62, 62% male, 53% ECOG PS 0 were available from 22 1st line mCRC studies conducted from 1997-2006; 12 tested targeted (anti-angiogenic and/or anti-EGFR) regimens. The relationship between PFS (first event of progression or death) and OS was evaluated at patient-, trt-arm-, and trial-levels using correlation (corr.) coefficients and R2 (closer to 1 the better) from weighted least square (WLS) regression of arm-specific survival rates and trial-specific hazard ratios (HRs), estimated using Cox and Copula bivariate models. The concordance of significance (CoS) of the treatment effects (TEs) on both endpoints was calculated. Results: 44% pts received a targeted regimen. Median PFS was 8 and OS was18 months. The corr. between PFS and OS was modest at all three levels with low CoS in TE comparisons (see Table). Analyses limited to trials testing targeted trts, non-strategy trials, or superiority trials did not improve surrogacy. Conclusions: In modern mCRC trials, where survival post-first progression exceeds time to first progression, PFS TEs do not reliably predict TEs on OS. Nonetheless, until alternative endpoints of clinical benefit can be validated, PFS remains a relevant primary endpoint for 1st line mCRC trials, as our data demonstrate that the ability for any agent to produce an OS benefit from a single line of therapy is challenging. [Table: see text]

3520 Background: EOTR has been suggested as a potential surrogate for overall survival (OS) in patients (pts) with mCRC and allows early assessment of treatment efficacy, facilitating adaptive trial design. We assessed at the individual patient level, the correlation between EOTR (complete or partial response) at 6, 8 and 12 weeks (wk), OS and progression free survival (PFS) in pts with mCRC treated with 1stline chemotherapy with or without a targeted agent as a first step in a surrogacy demonstration. Methods: IPD from 13,949 pts enrolled on 15 randomized Phase III trials in 1st line mCRC were used; 8 trials included targeted (anti-angiogenic and anti-EGFR) agents. EOTR prognostic value was assessed by landmark analyses using Cox models stratified by treatment assignment. P-values <0.01 were considered statistically significant to account for multiple comparisons. Results: Of 13,949 pts, 11,987 had sufficient response data to be included in the analysis. Median OS was 21.7 months (mo) in pts with an EOTR vs. 16.5 mo without EOTR at 6 wk (p<.0001, Hazard Ratio [HR] 0.64, 95% confidence interval [CI] 0.58-0.70, c statistic [c] 0.55). HRs were similar whether pts were treated with targeted therapies (p<.0001, HR 0.68, 95% CI 0.58-0.80, x 0.54) or non-targeted therapies (p<.0001, HR 0.61, 95% CI 0.55-0.69, x 0.55). Median PFS was 8.4 mo in pts with EOTR at 6 wk vs. 7.0 mo in pts without EOTR (p<.0001, HR 0.79, 95% CI 0.73-0.85). EOTR at 8 and 12 wks were also significantly associated with longer OS and PFS. The prognostic value of EOTR at 6, 8 and 12 wks remained significant (p<0.0001) after adjusting for age, gender, performance statusand location of metastatic disease (lung or liver). Overall tumor response (to 26 wk) however provided superior OS prediction (p<.0001, HR 0.51, 95% CI, 0.47-0.56, CS 0.61) vs. EOTR. Conclusions: Early response measured at 6, 8 or 12 wk after starting 1st line treatment was a strong and independent predictor of both OS and PFS in patient with mCRC and warrants further consideration as a potential endpoint for future trials, particularly randomized phase II trials.