Citations

3618 Background: Current prognostic tools and staging systems in CC use relatively few patient (pt) characteristics; including additional covariates may improve prediction. Using the large ACCENT database, we constructed clinically based NGs for OS and TTR in stage III CC that better separate pts into risk groups compared to AJCC v7 staging. Methods: 15,936 stage III pts accrued to phase III clinical trials since 1989 were used to construct Cox models for TTR and OS. Variables included age, sex, race, BMI, performance status, tumor grade, tumor stage, ratio of positive lymph nodes to nodes examined, number/location of primary tumors (any multiple versus single left, right, or transverse), and treatment (5FU variations vs. 5FU with oxaliplatin or irinotecan). Missing data (<18%) were imputed, continuous variables modeled with splines, and clinically relevant pairwise interactions included if p < 0.001. Final models were internally validated via bootstrapping for corrected calibration and C-indices for survival data. NG-defined risk tertiles were compared to AJCC v7 stage III for observed 3-year (yr) TTR and 5-yr OS for a subset of 7400 pts with complete data. Results: All variables were statistically and clinically significant for OS; age and race did not predict TTR. No meaningful interactions existed. NGs for OS and TTR were well calibrated and associated with C-indices of 0.66 and 0.65, respectively, vs. 0.58 and 0.59 for AJCC. NG risk tertiles were better separated than AJCC groups, (3-yr TTR, 5-yr OS below), with fewer mid-risk NG pts. Removing treatment from NGs did not affect performance (C=0.66 for OS and 0.65 for TTR). Conclusions: The proposed ACCENT NGs are internally valid and have the potential to aid prognostication, decision-making, and patient/physician communication in pts with stage III CC. [Table: see text]

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]

3514 Background: In the CORRECT phase III trial, the multikinase inhibitor regorafenib (REG) demonstrated significant improvement in overall survival (OS) and progression-free survival (PFS) vs placebo (Pla) in patients with metastatic colorectal cancer (mCRC) whose disease had progressed on other standard therapies. An exploratory biomarker subanalysis was conducted to identify protein biomarkers with potential predictive or prognostic value. Methods: Fifteen proteins of interest, many of which are involved in angiogenesis, were quantified by multiplex immunoassay or ELISA in baseline plasma samples collected at study entry from 80% (611/760) of patients. Potential predictive and prognostic effects were evaluated. Results: The biomarker subpopulation was representative of the overall study population in terms of OS and PFS. Using OS as the clinical endpoint, Tie-1 was the only protein whose level demonstrated significant correlation with efficacy (low protein group: REG/Pla, HR 0.87; high protein group, HR 0.56; interaction, p=0.035). Using PFS as the clinical endpoint, von Willebrand factor (VWF) was the only protein whose level demonstrated significant correlation with efficacy (low protein group: REG/Pla, HR 0.39; high protein group, HR 0.60; interaction, p=0.02). Following correction for multiple testing, neither Tie-1 nor VWF data retained statistical significance. Baseline levels of IL-8 and placental growth factor (PlGF) were found to have prognostic value for OS (IL-8: high/low protein levels, HR 3.48, p<0.001; PIGF: HR 1.81, p=0.002). IL-8 was also prognostic for PFS (high/low protein levels: HR 1.63, p<0.001). Conclusions: None of the plasma proteins examined showed significant predictive value for REG efficacy after multiple testing correction. The association between baseline levels of Tie-1/VWF and REG efficacy may be a hypothesis to be tested in further trials. Clinical trial information: NCT01103323.

3501 Background: Cumulative neurotoxicity commonly leads to early discontinuation of oxaliplatin-based therapy. In a relatively small, prematurely-discontinued, randomized study, IV CaMg was associated with reduced oxaliplatin-induced sNT (Grothey, JCO, 2011). N08CB was designed to definitively test whether IV CaMg significantly decreases cumulative oxaliplatin-related sNT. Methods: 353 pts with colon cancer undergoing adjuvant therapy with FOLFOX were randomized to 3 arms: IV CaMg (1g calcium gluconate, 1g magnesium sulfate) before and after oxaliplatin vs PL before and after vs CaMg before and PL after. The primary endpoint was cumulative sNT repeatedly measured by the sensory subscale of the EORTC QLQ-CIPN20. Secondary endpoints, using CTCAE 4.0 and an oxaliplatin specific neurotoxicity scale, were also assessed. Acute neuropathy data were also collected for 5 days following each oxaliplatin dose. The area under the curve (AUC) of the sensory subscale during the treatment cycles was used as summary measures for comparison. The Wilcoxon rank-sum tests were conducted for each treatment versus placebo arm, at 2.5%, adjusting for multiplicity using Bonferroni’s approach. Results: CaMg did not reduce cumulative sNT. Primary and secondary analyses data are summarized in the Table. In addition, there were no significant differences between arms regarding oxaliplatin administered doses or chemotherapy discontinuation rates. Also, there were no substantial differences in acute neuropathy scores or side-effects between study arms. Conclusions: This study does not demonstrate any activity of IV CaMg as a neuroprotectant against oxaliplatin-induced neurotoxicity. Clinical trial information: NCT01099449. [Table: see text]

e14564 Background: Recent long-term clinical trial follow-up suggests that adding Ox to a fluoropyrimidine (FP) may provide less benefit in adjuvant CC than originally believed (Tournigand JCO 2012). In addition, emerging data on tissue biomarkers such as microsatellite mismatch repair (MMR) and the 12-gene Recurrence Score (RS) suggest these assays may be helpful in better defining treatment benefit, and a new report provides evidence that RS may specifically predict the value of Ox (O'Connell ASCO 2012). In view of these developments we sought to document current use of adjuvant chemotherapy and physician perceptions about these decisions. Methods: U.S.-based oncologists were recruited to complete a survey and contribute treatment data for their last three patients (pts) with stage II disease and last pt with a stage III tumor. Results: 25 gastrointestinal cancer clinical investigators and 77 practicing oncologists participated, providing data from a total of 408 cases (92% treated since 2011). Findings from the two groups are similar and are presented in aggregate. A median of 9 and 15 pts annually were evaluated with Stage II and III tumors, respectively. Clinicians stated that they require a median of a 5% absolute reduction in relapse rate to use a FP alone and an additional 5% reduction to add Ox. Ox/FP was administered to 95 of 102 pts with stage III tumors (93%) and 85 of 306 pts with stage II disease (28%), particularly to those under age 70 or with T4 tumors (Table). MMR was evaluated in 127 pts (42%) with stage II and 20 pts (20%) with stage III disease. RS was obtained for 46 pts (15%) with stage II tumors, but only 2 pts (2%) with stage III. Conclusions: Adjuvant Ox is employed widely in spite of the fact that it may provide less benefit than many oncologists report requiring to initiate its use. However, several recent research developments may be laying the groundwork for a change in this treatment practice. [Table: see text]

TPS3634 Background: Vascular endothelial growth factor (VEGF) and the VEGF receptor-2 (VEGFR-2) regulate angiogenesis and are overexpressed in CRC. RAM is a fully human IgG1 monoclonal antibody that inhibits binding of VEGF ligands to VEGFR-2 and inhibits VEGFR-2 activation and signaling. In a preclinical study, antiangiogenic and antitumor effects were observed when DC101, an antibody that targets murine VEGFR-2, was administered to mice bearing human colon cancer xenografts. Antitumor activity for RAM has been demonstrated in a Ph I study in pts with solid tumors over a wide range of RAM dose levels and in a Ph II study with RAM + mFOLFOX-6 as 1st-line therapy in pts with mCRC. Methods: This ongoing, randomized, double-blind, placebo-controlled Ph III study includes mCRC pts with measurable or nonmeasurable disease and ECOG performance status of 0-1 who have experienced disease progression during or within 6 months following 1st-line therapy with BEV, OXALI, and any FP. Randomization is stratified by geographic region, KRAS status, and time to progression after initiation of 1st-line therapy. Pts are randomized 1:1 to either RAM 8 mg/kg or PL every 14 days. Pts in both arms receive FOLFIRI (irinotecan: 180 mg/m2, folinic acid: 400 mg/m2, 5-fluorouracil: 400 mg/m2 bolus followed by 2400 mg/m2 continuous infusion over 46-48 hours). The primary endpoint is overall survival (OS). The sample-size estimate assumes 85% power to detect at least a 2.5-month median OS difference (HR = 0.8) between treatment arms with a 1-sided alpha of 0.025. Secondary endpoints include progression-free survival, tumor response, safety, pharmacokinetics, immunogenicity, and correlations between biomarkers and clinical outcome. CRC tissue and blood collection is mandatory for biomarker analyses. As of 05 January 2012, 238 of 1050 planned pts have been enrolled from 100 sites in North America, South America, Europe, Asia, and Australia.

1557 Background: Peripheral neuropathy (PN), a common and intrusive side effect of chemotherapy in clinical trials, has been assessed via the clinician-rated common terminology criteria for adverse events (CTCAE) and/or patient-reported outcome (PRO) measures (Morton, ASCO, 2005). We assessed the relative sensitivity of CTCAE and PRO measures for evaluating interventions for preventing and ameliorating CIPN. Methods: Data from285 patients in two prevention trials (N05C3, N04C7) and 432 patients from three intervention trials (N00C3, N01C3, N06CA) were analyzed separately. CTCAE version 3.0 item for neuropathy was compared to 2 NCCTG numerical analogue CIPN items, 6 EORTC CIPN20 individual items, 2 McGill Pain Questionnaire items, and one Brief Pain Inventory item. The sample size provided over 80% power to detect a true Spearman rank correlation of 0.15 assessed the relationship between CTCAE and PRO measures. Results: Results from both the prevention and treatment trials were similar in terms of the relationship between the CTCAE and PRO measures. No correlation coefficients between the CTCAE and any of the PRO items at baseline were above 0.35, with the majority around 0.2. Higher scores for the numbness items were observed than for the CTCAE in 47% of the patients at baseline and 39% during treatment in the treatment trials. Many patients had severe numbness PRO scores but mild CTCAE scores (12%) at baseline and (8%) during treatment in the treatment trials. Results for the numbness and tingling PRO measures were redundant. The correlations of the CTCAE with pain were weak, all below 0.35 at baseline with differences as much as 29 points on average on a 0-100 transformed scale. Conclusions: The CTCAE and PRO measures of PN measure different constructs. The CTCAE includes both functional and ADL/motor aspects which may or may not be related to the singular constructs of pain, numbness, tingling, or adjectival characteristics of pain assessed by the PRO measures. The two measures cannot be used in place of each other.

6520 Background: We previously reported that alternative cutpoints and alternate categorical metrics to RECIST standards provided no meaningful improvement in OS prediction. Here, we sought to identify and validate continuous, longitudinal TM-based metrics for predicting OS. Methods: Data from 13 trials (1739 patients with sufficient imaging-based measurements from breast, lung or colon cancer) were randomly split (60:40) into training and validation datasets and landmarked at 12-weeks (w). Multiple candidate metrics that capture tumor curve trajectory were considered: first slope (or % change) from baseline to 6 w, last slope (or % change) from 6 w to 12 w, and indicator of increase (<5% (includes no increase or a decrease) vs. ≥5%) from the prior assessment (baseline to 6 w, 6 w to 12 w). Multivariable Cox models stratified by study and number of baseline target lesions (<3 vs. >3) and adjusted for baseline tumor burden (ratio of the sum of lesions/number of lesions) were fit for each tumor type. Predictive ability was assessed via concordance (c)-index (0.5: no association to 1.0: perfect association), and hazard ratios/p-values (HR/p). Results: Patients whose tumor size increased by at least 5% from the prior assessment, as well as whose tumors showed a positive slope (or % change) from 6 to 12 w (indicating tumor growth) had worse OS. The first slope (or % change) metric was less consistent, with an initial decrease in slope suggesting worse OS in some cases. Predictive ability of these metrics varied across tumor type with poorest prediction in Breast (Table). Conclusions: Continuous TM-based metrics performed no better than categorical RECIST metrics for OS prediction. [Table: see text]

3636 Background: In the CORRECT phase III trial, the multikinase inhibitor REG demonstrated significant improvement in overall survival (OS) and progression-free survival vs placebo (Pla) in patients (pts) with mCRC whose disease progressed on other standard therapies. The most frequent REG-related grade ≥3 adverse events (AEs) of interest were hand–foot skin reaction (HFSR), fatigue, diarrhea, hypertension, and rash/desquamation. We explored whether the impact of REG in pts aged ≥65 years differed from that in younger patients. Methods: Pts with mCRC progressing following all other available therapies were randomized 2:1 to receive REG 160 mg once daily (n=505) or Pla (n=255) for the first 3 weeks of each 4-week cycle. The dose could be modified to manage AEs. The primary endpoint was OS. We report efficacy, safety, and dosing data from REG recipients by age. Results: The REG treatment group included 309 pts <65 years (307 evaluable for safety) and 196 pts ≥65 years (193 evaluable for safety). The OS hazard ratio (REG/Pla) was 0.72 (95% confidence interval [CI] 0.56–0.91) in pts <65 years and 0.86 (95% CI 0.61–1.19) in pts ≥65 years (interaction p-value = 0.405). Median OS was 6.7 vs 5 months for REG vs Pla in pts <65 years, and 6.0 vs 5.6 months, respectively, in pts ≥65 years. Most pts experienced drug-related AEs (<65 years: 93.8%; ≥65 years: 91.7%). The rates of grade ≥3 REG-related AEs of interest and dose modifications are shown in the Table. In pts <65 years vs ≥65 years, median (interquartile range [IQR]) duration of REG was 7.6 weeks (6.6–15.4) vs 7.1 weeks (5.1–17.2), median (IQR) daily REG dose was 160.0 mg (134.6–160.0) vs 160.0 mg (137.5–160.0), and median (IQR) proportion of planned REG dose was 83.3% (65.7–100.0) vs 78.6% (66.7–100.0), respectively. Conclusions: In the CORRECT trial, REG demonstrated an OS benefit in pts <65 years and ≥65 years. Safety and tolerability of REG appeared to be similar in both age subgroups. Clinical trial information: NCT01103323. [Table: see text]

3502 Background: Regorafenib (REG) is an oral multi-kinase inhibitor. The CORRECT trial was conducted to evaluate REG in patients (pts) with mCRC who had progressed after all approved standard therapies. Methods: Enrollment criteria included documented mCRC and progression during or ≤3 months after last standard therapy. Pts were randomized 2:1 to receive best supportive care plus either REG (160 mg od po, 3 wks on/1 wk off) or placebo (PL). The primary endpoint was overall survival (OS). Secondary endpoints included progression-free survival (PFS), overall response rate, disease control rate, safety and quality of life (QoL). Efficacy analyses across prespecified subgroups were evaluated using univariate Cox regression. Results: 760 pts were randomized (REG: 505; PL: 255). The OS primary endpoint was met at a preplanned interim analysis. OS and PFS were significantly improved in REG arm compared to PL arm: hazard ratio (HR) for OS 0.77 (95% CI 0.64-0.94, 1-sided p=0.0052), median OS 6.4 vs 5.0 mos; HR for PFS 0.49 (95% CI 0.42-0.58, 1-sided p<0.000001), median PFS 1.9 vs 1.7 mos. Comparable OS and PFS benefits were observed in exploratory subgroup analyses by region, age, time from diagnosis of mCRC to randomization, prior lines of treatment, and KRAS status (shown in table). The most common grade 3+ AEs related to REG were hand-foot skin reaction (16.6%), fatigue (9.6%), hypertension (7.2%), diarrhea (7.2%) and rash/desquamation (5.8%). QoL data will be presented. Conclusions: REG demonstrated statistically significant improvement in OS and PFS over PL, as well as comparable efficacy benefits across pt subgroups analyzed. [Table: see text]