Goldberg, Richard M.

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]

3523 Background: The association of KRAS or BRAFV600E mutations with prognosis in colon cancers has been inconsistent. Since primary tumor site may influence outcome, we analyzed KRAS and BRAFV600E stratified by tumor site in resected stage III colon cancers from a randomized adjuvant trial of mFOLFOX6 + cetuximab chemotherapy (N= 2,686) where no survival difference by treatment was found. Methods: 2,580 tumors were analyzed for mutations in BRAFV600E (exon 15) or KRAS (codons 12, 13), and for deficient DNA mismatch repair (dMMR). Cox models were used, adjusting for mutation status, age, sex, treatment, T-stage, histologic grade, nodal status, tumor site, and MMR. After study initiation, eligibility was restricted to patients (pts) with KRAS wild-type (WT) tumors. At a median follow-up 4.1 yrs, 83% of pts are alive. Results: KRAS and BRAFV600E mutations were detected in 716 (28%) and 346 (14%) tumors, respectively; dMMR was found in 314 (12%). Proximal (to splenic flexure) tumors (50%) were associated with older age and were more likely to be high grade (33 vs 18%), T-stage3,4 (88 vs 82%), mutated for KRAS (33 vs 23%) or BRAFV600E (23 vs 4%), and dMMR (21 vs 3%)[all p <0.02]. Pts with distal vs proximal tumors showed improved disease-free survival (DFS)[ HR 0.7, 95% CI (0.6-0.9); p<0.01 unadjusted for KRAS or BRAF;]. Mutant KRAS [HR=1.5 (1.2-1.7); p<.0001] or mutant BRAF [HR=1.4 (1.1-1.7); p=0.02] were each independently associated with worse DFS. The KRAS and tumor site interaction was significant (unadjusted pinteraction=0.02; adjusted pinteraction=0.07), with poorer DFS among distal tumors having mutant KRAS [HR 1.7 (1.3-2.2); p<.0001]. No interaction was observed for BRAFV600E and tumor site, despite worse DFS for mutant BRAFV600E among proximal tumors [HR 1.3 (1-1.8); p=0.04]. Conclusions: The adverse prognostic impact of KRAS, but not BRAFV600E, mutations was confined to the distal colon. This finding underscores the importance of tumor site in the interpretation of the prognostic impact of KRAS status, and motivates similar analyses in pts with advanced disease.

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.

3510 Background: Prediction of 5-FU-related adverse events (5FU-AEs) continues to be problematic. Pharmacogenetic studies on the rate-limiting enzyme in 5-FU metabolism, dihydropyrimidine dehydrogenase (DPD), suggest a link between three variants and both decreased enzyme activity and increased toxicity: c.1905+1 G>A (DPYD*2A; rs3918290), c.1679 T>G (I560S; DPYD*13; rs55886062), and c.2846A>T (D949V; rs67376798). Since the adverse impact of DPYD variants on 5-FU toxicity remains controversial, we determined associations between the three known DPYD variants and 5FU-AEs in stage III CC patients receiving FOLFOX or FOLFIRI (+ cetuximab) after curative resection. Methods: 2886 patients were genotyped by multiplexed single-base extension assays using the IPLEX Gold Kit and analyzed on the Sequenom MassARRAY system. Grade 3+ AEs were recorded per CTCAE v3. Fisher’s exact test, unequal variance two-sample t-test, and Wilcoxon rank sum test were used to compare categorical variables, continuous variables, and counts between patients with wild-type and mutant status. Logistic regressions were used to assess univariate and multivariate associations. Results: Patients displayed the following characteristics: male gender 53.2%, median age 58 [19-86], proficient DNA mismatch repair status 88.6%, PS-0 76.6%, + irinotecan 8.1%, and + cetuximab 45.9%. A total of 27 (0.9%), 4 (0.1%), and 32 (1.1%) patients carried the DPYD*2A, I560S, and D949V variants, respectively. Analysis identified significant associations between DPYD*2A and D949V variants and toxicity, with grade 3+ 5FU-AEs identified in 22 DPYD*2A carriers (OR=11.9, 95% CI 4.0-32.7, p<0.0001) and 22 D949V carriers (OR=5.5, 95% CI 2.5-12.1, p< 0.0001). No interaction effect was found between DPYD*2Aand D949V on grade 3+ 5FU-AEs (p = 0.98), nor on overall grade 3+ AEs (p = 0.97). No significant association was identified between I560S and grade 3+ 5FU-AEs. Conclusions: In the largest study to date, statistically significant associations were found between DPYD*2A and D949V variants and increased incidence of grade 3+ 5FU-AEs, suggesting utility in 5-FU toxicity prediction.

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]

10019 Background: Colon cancers with microsatellite instability (MSI) display resistance to 5-fluorouracil (5-FU), and in vitro resistance can be reversed by restoring DNA mismatch repair proficiency. 5-FU inhibits the thymidylate synthase (TS) enzyme and TS may predict clinical outcome after 5-FU-based chemotherapy. To define molecular predictors of prognosis, we analyzed TS, p53, chromosome 17p allelic imbalance (AI), and patient survival stratified by MSI status. Methods: Primary colon carcinomas from patients enrolled in five 5-FU-based adjuvant therapy trials were analyzed for MSI and 17p AI using 11 microsatellite markers (MSI-H: ≥ 30% of the loci demonstrating instability). For 17p AI, markers included D17S261 and TP53 at or near the p53 locus. Expression of DNA mismatch repair (hMLH1, PharMingen; hMSH2; Oncogene), TS (TS106, Zymed), and p53 (D07, Novacastra) proteins were analyzed by immunohistochemistry. Correlations between markers and associations with overall survival (OS) were determined. Patients were censored at 5 years for DFS and at 8 years post study randomization for overall survival (OS) data. Results: Of 320 Dukes’ stage B2 and C cancers studied, 60 of 320 (19%) were MSI-H. TS expression variables (intensity, extent, weighted score) were similar in MSI-H and MSI stable/low frequency (MSS/MSI-L) cancers; similar results were found using DNA mismatch repair (dMMR) proteins. MSI-H tumors had lower stage (p= 0.0007), fewer metastatic lymph nodes (p= 0.004), and improved OS (vs. MSS/MSI-L tumors; p= 0.01). Loss of dMMR proteins was also associated with better OS (p= 0.006). None of the TS variables were prognostic for OS. Histologic grade (p= 0.0008) and nodal status (p= 0.0002) were associated with OS in contrast to 17p LOH or p53. Only MSI status or dMMR, histologic grade, and tumor stage were independent markers for OS. Conclusions: MSI-H tumors show earlier stage at presentation and better stage-adjusted survival rates. MSI status and TS expression were unrelated and TS was not prognostic, suggesting that TS levels cannot explain therapeutic resistance to 5-FU reported in MSI-H colon cancers. [Table: see text]

3517 Background: The combination of oxaliplatin, fluorouracil, and leucovorin is effective in many patients with colon cancer treated in either the advanced or adjuvant disease setting. To better identify the risks & benefits of this regimen for elderly patients we compared safety & efficacy data for the FOLFOX4 regimen (oxaliplatin plus fluorouracil/leucovorin administered bimonthly) in patients over & under 70 years of age. Methods: We conducted a retrospective analysis of 3742 patients (614 aged ≥ 70) with colorectal cancer enrolled in four clinical trials using the same FOLFOX4 regimen as adjuvant therapy, or as first- or second-line therapy in advanced disease. Endpoints included grade ≥ 3 adverse events, response rate (RR) (in studies of advanced disease), progression (metastatic)/relapse free (adjuvant) survival (P/RFS), overall survival (OS), and dose intensity. Results: Age ≥ 70 was associated with slightly higher rates of neutropenia and thrombocytopenia but no other grade ≥ 3 adverse events (see table). There was no difference in 60-day mortality (1.1% vs 2.3%, p=0.20). We observed no significant difference in any measure of therapeutic impact of FOLFOX based on age, including P/RFS, OS, response rate, or dose intensity (see table). Conclusions: The FOLFOX4 regimen maintains its efficacy/safety ratio in elderly patients with colorectal cancer, and was administered per protocol at similar drug doses compared to the younger patients enrolled on these trials. Age alone should not be a factor limiting the use of FOLFOX4 provided patients are carefully evaluated and monitored. This analysis was supported by Sanofi-Aventis [Table: see text] [Table: see text]

3516 Background: A previous report noted that patients (pts) in the phase III study of IFL ± BV who received BV had significantly longer PFS and OS regardless of whether or not they responded according to RECIST criteria (Mass et al, ASCO 2005). It is unclear if this phenomenon is specific to the addition of a biologic to chemotherapy (CT) or a more general benefit from improved therapy since it has been suggested that stable as well as responding disease is beneficial for pts. We repeated the analysis of Mass et al on pts enrolled in N9741, a study which established the superiority of FOLFOX over IFL and contained no biologic compound. Methods: For this retrospective analysis, pts were defined as ‘responders‘ or ‘nonresponders‘ according to whether criteria for complete or partial response (by RECIST -AVF2107g or WHO criteria -N9741) were either achieved (responders) or not achieved (nonresponders). PFS and OS were estimated from Kaplan-Meier curves; hazard ratios (HR) for progression and death in each subgroup were estimated by Cox regression. Results: In both trials, response was associated with superior outcome. However, statistically significant improvements in PFS and OS were observed in both responders and non-responders treated with either IFL + BV or FOLFOX versus IFL, and the magnitude of improvement was similar regardless of response ( Table ). Conclusions: Analysis of two large recent mCRC phase III trials clearly demonstrate that pts who do not achieve a response according to traditional criteria still have significant benefit from the superior regimen, with a similar magnitude of benefit for responders and non-responders, regardless if the regimen called for CT alone or included the antiangiogenic biologic BV. These data support the conclusion that PFS and the percentage of pts experiencing tumor control may more accurately reflect pt benefit than does response rate in phase III trials in mCRC. [Table: see text] [Table: see text]

3515 Background: Patients with metastatic colorectal cancer (mCRC) treated with 5Fluorouracil plus leucovorin (5FU/LV) have a median life expectancy (LE) of approximately12 months. The addition of irinotecan, oxaliplatin, bevacizumab and cetuximab has increased LE significantly. Although they have been widely adopted, little is known about the financial impact of these new drugs. Methods: Using published reports and aggregate data from NCCTG 9741, we developed a Markov Model which assumes forward progression through up to three lines of therapy compared to 5FU/LV alone. Patients who do not die of toxicity (tox) transition through supportive care prior to death. State changes are based on progression and dose-limiting toxicity. Drug costs are based on Average Sales Price. No other direct or indirect costs are included. Dose modifications for toxicity are defined as 80% of standard doses. Sensitivity analyses (SA) were performed on key variables. Results: LE, total drug costs, and cost-effectiveness (CE) ratios compared to single line-5FU/LV and FOLFOX for 9 commonly used treatement sequences are presented below. SA show that results are sensitive to progression rates,drug costs and length of time on supportive care. Changes in 1st line tox rates have a greater impact on final results than changes in 2nd or 3rd line therapy tox rates. Conclusions: Using drug costs alone, this model shows sequential combination therapy including all available agents to cost $2000-$2800K/week life gained ($100-$145K/year) compared to both 5FU/LV and FOLFOX. For clarity only 9 strategies are presented, but the model presented will contain multiple sequences consisting of 1–3 lines of therapy. Refined tox data, associated costs and quality of life adjustments are needed for realistic comparisons among specific combinations. Combination therapy may have CE ratios similar to other currently accepted intensive medical interventions. These data can help inform discussions of how the cost of care impacts patients, providers, and societies. [Table: see text] [Table: see text]

3509 Background: FOLFIRI or FOLFOX are 1st-line treatments (Rx) for MCRC. Cetuximab is an IgG1 Mab that targets the epidermal growth factor receptor (EGFR) and is approved as monotherapy or in combination with irinotecan in irinotecan-refractory, EGFR + pts with MCRC. CALGB 80203 randomized untreated MCRC pts to FOLFOX or FOLFIRI ± cetuximab (independent of EGFR status.) Methods: Pts with performance status 0–1 with tumor blocks available for EGFR analysis received either irinotecan 180 mg/m2 over 1.5 hours (h) or oxaliplatin 85 mg/m2 over 2h combined with LV 400 mg/m2 over 2h and 5FU 400 mg/m2 bolus, then 46–48h CI 5FU 2400 mg/m2 q o w. Cetuximab dose: 400 mg/m2 loading dose, then 250 mg/m2 qw. Rx continued until progression or toxicity; subsequent Rx was not mandated although information was collected on such rx. Accrual goal was 2200 pts with intended 1° endpt of overall survival (OS). 80203 closed administratively in 1/05 (due to slow accrual) with 238 pts accrued. 2° endpts of response rate (RR), progression free survival (PFS), duration of R and toxicity are now able to be analyzed. Results: Accrual: FOLFIRI (A) - 61; FOLFIRI + cetuximab (B) - 59: FOLFOX (C) - 60; FOLFOX + cetuximab (D) - 58; approx median follow-up (f/u) is 12 months. RR (CR + PR, not all yet confirmed): A - 34%; B - 42%; C - 32%; D - 55%. RR was similar in the FOLFIRI or FOLFOX arms (A+B v. C+D; 38% v. 43%, p=0.44; chi-square) while C225 containing arms (B+D) v. non-C225 arms (A+C) had a superior RR (49% v. 33%; p=0.014, chi-square) It is too early to tell if there are differences in PFS, duration of response or OS. No significant differences in gr III diarrhea or any gr IV toxicities were seen. Conclusions: These results suggest that FOLFIRI and FOLFOX are similar in efficacy for pts with untreated MCRC and that adding cetuximab to either in1st-line Rx appears to increase response rates. PFS and duration of response do not appear different at this analysis. Further f/u and an analysis of prospective companion correlative studies may help to further clarify these results. [Table: see text]