Grothey, Axel

675 Background: Recent retrospective analysis of CALGB/SWOG 80405 showed that left-sided colon cancers (LCC) respond differently to biological therapy compared with right-sided tumors. However, differences between rectal cancers (RC) and LCC remain undefined. Herein, we report our exploration of differences between these two groups. Methods: Individual patient data from 4182 patients (pts) with metastatic colorectal cancers, enrolled onto 8 first-line randomized trials, were pooled. Only pts with tumor locations that were clearly defined as LCC (splenic flexure to sigmoid) or RC were included in this analysis. Differences in pt characteristics and disease factors according to LCC vs. RC were identified. The prognostic effect of primary tumor location on OS and PFS was quantified via multivariable Cox proportional hazards modeling stratified by treatment arm within each study and adjusting for age, sex, performance status, and prior surgery. Results: In total, 2,479 (59%) pts with LCC and 1,703 (41%) pts with RC were identified. Pts with RC, compared with LCC, were more likely to be male (68% vs. 62%, p < 0.001), have lung metastases (mets) (56% vs. 37%, p < 0.001), and have 2 or more metastatic sites (64% vs. 60%, p < 0.02), whereas pts with LCC were more likely to have liver mets (84% vs. 76%, p < 0.001). RC had a greater frequency of KRAS mutations (41% vs. 37%, p = 0.04) than LCC but there were no differences in the frequency of BRAF mutations (5% vs. 4%, p = 0.2). In multivariable analysis, no differences in OS or PFS were observed between pts with LCC vs. RC. While risk of death did not differ by primary tumor location, across all pts with LCC or RC, those with liver mets had a 17% increased risk of death compared to those with lung mets (HR = 1.17, p = 0.03) after adjusting for effects of other variables. Forthcoming prognostic analysis of LCC vs. RC within grouped backbone treatments (e.g., FOLFOX and FOLFIRI) is underway. Conclusions: Tumors arising in the rectum may carry clinical and molecular features that are distinct from LCC. Further investigations are warranted to determine whether RC should be treated with the same chemo backbone and biological therapy as LCC.

668 Background: Ramucirumab is a human IgG1 monoclonal antibody antagonist of VEGFR-2. Overall survival (OS) and progression-free survival (PFS) in 2nd line FOLFIRI based treatment for metastatic colorectal cancer (mCRC) were improved with RAM therapy versus PBO in the RAISE trial. Recent work suggests mCRC primary tumor location is both prognostic and predictive; with improved OS and therapy-specific sensitivity observed in left (L)- vs right (R)-sided tumors. Given these findings, the RAISE trial data was subjected to post-hoc analysis to determine if sidedness influenced RAM efficacy. Methods: Primary tumor site was obtained. L-CRC was defined as the splenic flexure, descending and sigmoid colon, and rectum, while R-CRC included transverse, ascending colon and cecum. OS/PFS in L and R subgroups were analyzed via Kaplan-Meier method and unstratified log-rank test (treatments within subgroup), unstratified Cox proportional hazards model (estimate hazard ratio [HR] and 95% CI), and Wald test (treatment-by-subgroup interaction). Results: Tumor location was available for 1012/1072 (94%) patients, 699 L- and 313 R-CRC. Baseline characteristics were balanced between arms. RAM treatment enhanced L-CRC median OS by 2.5 mo (median 14.5 vs 12.0 mo) with a HR (95% CI) = 0.807 (0.675, 0.965), P = 0.019; compared to a 1.1 mo increase in median OS in R-CRC vs PBO (12.7 vs 11.6) with a HR (95% CI) = 0.971 (0.750, 1.258), P = 0.823; and, RAM enhanced L-CRC median PFS by 1.6 mo (6.0 vs 4.4 mo) and HR (95% CI) = 0.776 (0.664, 0.906), P = 0.001 compared to a 1.1 mo increase in median PFS R-CRC vs PBO (5.6 vs 4.5) with a HR (95% CI) = 0.855 (0.674, 1.084), P = 0.197. The treatment-by-subgroup interaction for both OS and PFS was not significant ( P = 0.276, 0.578, respectively). Conclusions: Despite L-CRC patients having longer OS/PFS and a seemingly stronger RAM treatment effect than R-CRC, the non-significant interaction test cannot verify sidedness as being predictive of RAM efficacy. The current study confirms ramucirumab benefits mCRC patients regardless primary tumor location. Clinical trial information: NCT01183780.

551 Background: Sorafenib inhibits various pro-angiogenesis pathways including PDGFR-B, a factor associated with resistance to anti-VEGF therapy. A previous phase II trial in patients with chemorefractory metastatic CRC demonstrated a 63% disease control rate with a combination of bevacizumab (BEV) and sorafenib. This phase I trial sought to determine the MTD of BEV and sorafenib combined with standard cytotoxic therapy for advanced gastrointestinal (GI) cancers. Methods: Patients with advanced GI malignancies appropriate for irinotecan-based therapy were enrolled (14 with CRC, 3 gastroesophageal). A standard 3 + 3 design was used with 3 escalating sorafenib dose levels (DL): (1) 200 mg po daily, days 3-7, 10-14; (2) 200 mg po twice daily, days 3-6, 10-13; and (3) 200 mg po twice daily, days 3-7, 10-14. FOLFIRI: irinotecan 180 mg/m2 d1, leucovorin 400 mg/m2 d1, 5-fluorouracil (FU) bolus 400 mg/m2 d1, 5-FU infusion 2400 mg/m2d1-2 and BEV 5 mg/kg d1. 1 cycle = 14 days. Results: Seventeen pts were enrolled, median age of 56 (range 32 and 81). Two pts were replaced, as they did not complete DLT evaluation, leaving 15 evaluable pts. Four evaluable pts at DL1 and 6 pts at DL2 had no DLTs. At DL 3, the first cohort of 3 pts did not experience any DLTs. In the second cohort of 3 pts, 2 pts experienced DLTs (asymptomatic G3 hypophosphatemia, G3 dehydration and diarrhea). MTD was determined to be DL2: sorafenib 200 mg PO twice daily, days 3-6, 10-13 combined with FOLFIRI and BEV at standard doses. Of the 15 evaluable pts, 4 pts had PR, 8 pts had SD as best response, 1 pt had PD, and 2 pts discontinued treatment prior to first tumor assessment. The median number of cycles was 10 (range 1-37). Three pts with CRC had disease control > 12 months. Conclusions: The MTD of this regimen is sorafenib 200 mg PO twice daily, days 3-6,10-13 combined with standard doses of FOLFIRI and BEV. Dual VEGF inhibition combined with cytotoxic therapy may provide prolonged disease stabilization for select patients with advanced GI malignancies. Supported by CA69912 and CA15083. Clinical trial information: NCT01383343.

514 Background: Randomized trials and OCSs have demonstrated that BV treatment in 1st-line (1L), in 2L, and across multiple lines is associated with longer survival in patients (pts) with mCRC. This analysis was aimed at comparing the effectiveness of BV after 1st disease progression (PD) between male and female mCRC pts who received 1L BV-containing therapy in a real-world setting. Methods: ARIES is a large, prospective OCS that enrolled pts who received BV and chemotherapy (CT) for 1L mCRC. Post-PD effectiveness was assessed for men and women characterizing BV use by cumulative and dichotomous approaches. The primary analysis treated BV exposure as cumulative BV doses after 1st PD and post-progression overall survival (ppOS) as the time from 1st PD to death. A time-dependent Cox regression model was fitted to assess the effect of cumulative BV exposure on ppOS, while controlling for potential confounders. A dichotomous secondary analysis characterized BV exposure as receipt of CT + BV (BBP) or CT alone (No BBP) within 2 months after PD and ppOS as time from 1st PD + 2 months to death. Results: Among the 1,550 1L mCRC pts enrolled, 1,199 (532 women) had PD. In the primary analysis, hazard ratios (HRs) for ppOS decreased, on average, by 1.2% with each additional BV dose. When stratified by sex, the average risk reduction per BV dose over 15 doses was 1.8% in women and 0.7% in men. In the secondary analysis that included 331 women (BBP, 180; No BBP, 151) and 417 men (BBP, 245, No BBP, 172) who received BV ± CT within 2 months post-PD, the HRs for ppOS with BBP treatment were 0.46 (95% CI, 0.35–0.59) in women and 0.52 (95% CI, 0.41–0.67) in men. Statistical interaction tests for differences in the effectiveness of BV between men and women were negative for primary and secondary analyses (P of 0.58 and 0.77). Protocol-specified adverse events occurred in 17.8% of women and 10.2% of men in the BBP population; this difference was largely related to rates of hypertension (8.3% vs 2.4%, respectively). Conclusions: In ARIES, the effectiveness of BV after first PD was not statistically different between women and men with mCRC. Clinical trial information: NCT00388206.

467 Background: Regorafenib (REG) is an oral multikinase inhibitor that has recently demonstrated significant overall survival benefit vs placebo in the randomized phase III CORRECT study. We examined the time course of adverse events (AEs) in the CORRECT study. Methods: Regorafenib (REG) is an oral multikinase inhibitor that has recently demonstrated significant overall survival benefit vs placebo in the randomized phase III CORRECT study. We examined the time course of adverse events (AEs) in the CORRECT study. Results: The safety population comprised 753 patients (pts): REG n=500; placebo n=253. The mean treatment duration was 12.1 ± 9.7 weeks in the REG group and 7.8 ± 5.2 weeks in the placebo group. Treatment-emergent AEs occurred at any grade in 99.6% of REG pts and 96.8% of placebo pts, at grade 1/2 in 21.6% and 47.8%, respectively, at grade 3 in 56.0% and 26.5%, respectively, and at grade 4/5 in 22.0% and 22.5%, respectively. AEs occurring in ≥10% more REG than placebo pts were fatigue, hand–foot skin reaction (HFSR), anorexia, diarrhea, weight loss, voice changes, hypertension, rash/desquamation, oral mucositis, fever, hyperbilirubinemia, low platelet count. The most frequent AEs deemed to be regorafenib related were HFSR, fatigue, diarrhea, hypertension, and rash/desquamation. The frequency of these AEs over time is shown in the Table. The incidence of HFSR, fatigue, hypertension, and rash/desquamation peaked in cycle 1 and tapered to a relatively stable lower incidence over later cycles. The incidence of diarrhea remained relatively constant throughout treatment. AEs led to dose modification in 66.6% of pts in the REG group and 22.5% in the placebo group. Data on dose intensity across treatment cycles will be presented. Conclusions: In the CORRECT trial, the incidences of the most common AEs in the REG group peaked early during treatment. There appeared to be no evidence for cumulative toxicity of REG. Clinical trial information: NCT01103323. [Table: see text]

381 Background: In the CORRECT Ph3 trial, regorafenib demonstrated significant improvement in OS and PFS vs. placebo in subjects with metastatic colorectal cancer (mCRC) who had progressed on standard therapies. An exploratory biomarker substudy was conducted on samples collected from subjects enrolled in CORRECT. Methods: DNA was isolated from archival tumor tissue and fresh baseline plasma samples that were available from 239 (31%) and 503 (66%) subjects enrolled in CORRECT, respectively. Mutations in KRAS, PIK3CA and BRAF were evaluated via BEAMing technology. Results: Mutations were readily detected in DNA isolated from both tumor and plasma samples: KRAS: 59/69%; PIK3CA: 12/17% and BRAF: 1.5/3.4%. The frequency of KRAS mutation detected in tumor samples via BEAMing (59%) was identical to the frequency determined from pre-existing “historical” KRAS mutation data that was available from 96% of the subjects enrolled in the study. Concordance among the mutations detected via BEAMing in tumor vs. plasma was 76% (KRAS), 88% (PIK3CA), and 97% (BRAF). A subset of CRC which was found to be KRAS-wildtype in DNA from archival tumor, but KRAS-mutant in DNA from fresh plasma was identified and may represent subjects whose KRAS mutational status had changed during prior therapy. Correlative subgroup analyses demonstrated that regorafenib mediated a trend for clinical benefit vs. placebo in both KRAS wildtype and mutant subgroups identified by plasma BEAMing (OS: KRAS WT, HR: 0.67, 95% CI: 0.41–1.08; KRAS mutant, HR: 0.81, 95% CI: 0.61–1.09; interaction p=0.561). Similar results were noted for PIK3CA WT/mutant subgroups (OS: WT, HR: 0.75, 95% CI: 0.57–0.99; mutant, HR: 0.84, 95% CI: 0.47–1.50; interaction p=0.723). BRAF was not analysed due to the small number of BRAF-mutant samples. Conclusions: The mutational analysis of DNA isolated from fresh plasma is feasible and robust using the BEAMing platform and may better represent the mutational status of the tumor(s) that a mCRC patient harbors at the time of enrollment than does the mutational analysis of archival primary tumor tissue. Regorafenib was associated with clinical benefit (vs. placebo) in all mutational subgroups evaluated. Clinical trial information: NCT01103323.

710 Background: In the CORRECT phase III trial (NCT01103323), the multikinase inhibitor REG significantly improved overall survival (OS) and PFS vs placebo in patients with mCRC who had disease progression after other standard therapies (HR for OS: 0.77; 1-sided p =0.0052; Grothey 2013). A post-hoc exploratory subgroup analysis was conducted to evaluate patients in the REG treatment group who had a PFS longer than 4 months (long-PFS) defined as patients who progressed, died, or discontinued treatment for other reasons after 4 months. Methods: Of the505 patients randomized to REG in CORRECT, 98 (19.4%) were classified as having a long-PFS benefit. Baseline characteristics, safety, and dosing parameters were analyzed descriptively. Results: The long-PFS subpopulation was representative of the overall study population (Table). Long-PFS patients received a median of 6 cycles of REG (1-12), 92% received ≥5 cycles, and 20% had > 8 cycles. Overall 34% of patients had dose reductions and 87% had dose interruptions. The actual mean daily dose was 139 mg and the mean percent of the planned dose was 81%. Adverse events (AE) of any grade were experienced by all long-PFS patients, and the most common grade ≥3 AEs were hand-foot skin reaction (20%), hypertension (17%), diarrhea (17%), and fatigue (16%). Conclusions: A subset of 98 (19.4%) patients treated with REG in the CORRECT study had a PFS > 4 months, confirming the clinical benefit and tolerability of REG as a treatment option for patients with mCRC. Prospective validation of these findings in conjunction with biomarker analysis from real-life clinical experience is needed. Clinical trial information: NCT01103323. [Table: see text]

702 Background: Median overall survival (OS) in mCRC has significantly improved over the past 20 yrs, but the observed range of OS in pts remains wide; a large percentage of pts have OS <1 yr or >4 yrs. ARIES was a prospective OCS conducted from 2006–2012 that evaluated outcomes in pts receiving BV + chemotherapy (CT) for mCRC in general clinical practice. The objective of this analysis is to examine clinical characteristics of pts with long vs short OS. Methods: This analysis included 1,417/1,550 first-line (1L) BV-treated mCRC pts who died or had complete follow-up on study. Long OS was defined as OS within the upper quartile of the analysis population (range 42–67 mos); short OS was defined as OS within the lower quartile (range 0.3–12 mos). Progression-free survival (PFS) was estimated using Kaplan-Meier methods. Pt and disease characteristics and treatment patterns were described using summary statistics. Results: Pt and disease characteristics are shown in the Table. Median PFS was 22.3 mos (95% CI, 19.9–23.3) vs. 4.9 mos (95% CI, 4.6–5.4), in the long-OS vs. short-OS groups. More pts with long OS received any second-line (2L) therapy (71% vs. 46%), and were exposed to 5-fluorouracil, oxaliplatin, and irinotecan throughout the course of their disease (53% vs. 32%) compared with pts with short OS. KRAS/BRAF mutation status was not collected. Conclusions: Pts with long OS had better baseline performance status, primary tumors more likely to have been resected, and were more likely to have received 2L CT. Additional analyses of detailed treatment patterns and safety are ongoing. Clinical trial information: NCT00388206. [Table: see text]

735 Background: In the phase III CORRECT study, regorafenib significantly improved overall survival and progression-free survival (PFS) vs placebo in patients with treatment-refractory mCRC. CONSIGN (NCT01538680) was a large phase IIIb study that included 2872 patients from 25 countries; it was designed to provide continued access to regorafenib for patients with mCRC who failed standard therapy and to further characterize the safety of regorafenib. In CONSIGN, adverse events (AEs) and PFS were consistent with those reported in phase III studies. We present a retrospective subgroup analysis of patients enrolled in CONSIGN in the USA. Methods: Patients with mCRC who progressed on standard therapies and had an ECOG PS 0─1 received regorafenib 160 mg QD for the first 3 weeks of each 4-week cycle. Treatment was continued until disease progression, death, or unacceptable toxicity. The primary endpoint was safety. PFS (per investigator) was the only efficacy variable assessed. Results: A total of 364 patients in the USA were assigned to treatment (all evaluable for safety). The median age was 60 years; 38% and 62% had ECOG PS 0 and 1, respectively. KRAS mutation was present in 59%, KRAS wt in 38%; 74% had ≥ 3 prior regimens for metastatic disease. Median duration of treatment was 2.3 months (range: 0–30). Median PFS (95% CI) was 2.3 (2.0–2.6) months (2.1 months KRAS wt; 2.3 months KRAS mutant). NCI-CTCAE v4.0 grade ≥ 3 AEs occurred in 81% of patients and were considered drug-related in 53% (Table). Grade ≥ 3 hepatobiliary disorders occurred in 2%. Grade ≥ 3 treatment-emergent laboratory toxicities included bilirubin (9%), AST (6%), and ALT (3%). Conclusions: In patients from the USA enrolled in CONSIGN, the safety profile of regorafenib was consistent with that of the overall population and the known safety profile of regorafenib in mCRC. Median PFS was in the range of that reported in phase III trials. Clinical trial information: NCT01538680. [Table: see text]

656 Background: Patients (pts) with peritoneal metastases from CRC (pmCRC) have reduced OS compared to mCRC pts without peritoneal involvement. Here we further investigated the impact of number and location of metastases among pts receiving first-line systemic chemotherapy. Methods: Individual patient data were available on 9,265 pts (median age 64; 63% male; 93% ECOG PS 0-1; 68% colon primary tumor; brain metastases excluded) enrolled onto 12 first-line randomized trials (4 tested targeted regimens). Stratified multivariable Cox models were used to assess the associations with overall survival (OS); adjusted hazard ratios (HRadj) and 95% confidence intervals are reported (CI). Results: There were 7,963 (86%) pts with non-pmCRC (3,904 with one disease site; 4,059 with ≥2 disease sites), 191 (2%) pts with isolated pmCRC, and 1,111 (12%) non-isolated pmCRC. These groups were similar in age, race, and use of targeted chemotherapy. Compared to non-pmCRC, pts with pmCRC were more likely to be female (41% vs. 36%, p<.001), have colon primary tumors (85% vs. 67%, p<.0001), and have PS2 (10% vs. 6%, p<.0001). Compared to isolated pmCRC, pts with solitary non-peritoneal sites (both M1a) had significantly better OS (HRadj=0.78; CI, 0.64-0.94, p=.009) while pts with ≥2 non-peritoneal sites had similar OS (HRadj=1.06; CI 0.88-1.28, p=.535). OS of pts with pmCRC with a single other disease site (n=446) was similar to isolated pmCRC (HRadj=1.13; CI 0.91-1.40, p=.28), but those with pmCRC + ≥2 additional disease sites (n=665) had shortest survival (HRadj=1.44; CI 1.17-1.77, p<.001). A combination of peritoneal and liver metastases (n=821; HRadj=1.37, CI 1.12-1.67, p=.002) was associated with poorer survival compared with isolated pmCRC; but combination with extrahepatic sites (n=290; HRadj=1.15, CI 0.91-1.45, p=.25) was not. Conclusions: pmCRC pts have significantly worse survival than those with other solitary site mCRC. Among those with multiple disease sites, poorer survival is a function of increased number of metastatic sites and peritoneal involvement, which indicates prognostic heterogeneities among M1b pts.