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e13016 Background: Whole-genome sequencing (WGS) of formalin-fixed, paraffin-embedded (FFPE) samples could enable novel insights from archival sample collections, yet robust FFPE WGS is challenged by fragmented DNA, uneven genomic coverage & sequencing artifacts attributed to FFPE fixation. We report our proprietary extraction & library preparation methodology (SeqPlus) with high quality, uniform WGS sequencing performance comparable to that from fresh-frozen samples. Methods: We analyzed 20 paired esophageal carcinoma (EC) samples i.e., primary tumors & matched germline samples to assess SeqPlus performance on 10-15-year-old FFPE tissues, measure variant concordance between WGS and a high-depth sequencing panel (269 genes, 400x coverage) & identify novel genomic features. Results: At a targeted 70x WGS tumor sequencing depth, 93% of the genome was covered by ³ 20 reads, 99% of bases had 10x coverage & average duplicate reads were 31%. We noted similar transition/transversion ratios & mutational spectra as from fresh-frozen EC specimens, suggesting that extraction & library preparation contributes to prior FFPE artifacts. Concordance of tumor-specific SNVs & indels derived from WGS & targeted panel was high at 86%. All 76 targeted panel-detected variants above the WGS limit of detection (mutant allele frequency [MAF] > 10%) were detected by WGS, 2 variants (2 tumors) were detected only by WGS, and 12 variants at MAF ≤ 6% (9 tumors) were only detected by the targeted panel. Tumor WGS yielded SNV, indels & CNV findings beyond variants detected by targeted sequencing. WGS enabled detection of 10.4 putative cancer variants per tumor compared to 12 variants per patient from frozen specimens and a median of 7 (up to 16) cancer-associated variants in genes outside the targeted panel. WGS copy number analysis revealed CCND1, EGFR, TP63, and SOX2amplification, CDKN2A/B deletion and additional unrecognized genomic aberrations. Conclusions: Our study reinforces the utility of high-quality, uniform WGS sequencing of archival FFPE cancer samples with SeqPlus and unlocks the potential for massive-scale retrospective genomic analysis of archived pathology samples with associated clinical & outcomes data.

Purpose Panitumumab, a fully human anti–epidermal growth factor receptor (EGFR) monoclonal antibody that improves progression-free survival (PFS), is approved as monotherapy for patients with chemotherapy-refractory metastatic colorectal cancer (mCRC). The Panitumumab Randomized Trial in Combination With Chemotherapy for Metastatic Colorectal Cancer to Determine Efficacy (PRIME) was designed to evaluate the efficacy and safety of panitumumab plus infusional fluorouracil, leucovorin, and oxaliplatin (FOLFOX4) versus FOLFOX4 alone as initial treatment for mCRC. Patients and Methods In this multicenter, phase III trial, patients with no prior chemotherapy for mCRC, Eastern Cooperative Oncology Group performance status of 0 to 2, and available tissue for biomarker testing were randomly assigned 1:1 to receive panitumumab-FOLFOX4 versus FOLFOX4. The primary end point was PFS; overall survival (OS) was a secondary end point. Results were prospectively analyzed on an intent-to-treat basis by tumor KRAS status. Results KRAS results were available for 93% of the 1,183 patients randomly assigned. In the wild-type (WT) KRAS stratum, panitumumab-FOLFOX4 significantly improved PFS compared with FOLFOX4 (median PFS, 9.6 v 8.0 months, respectively; hazard ratio [HR], 0.80; 95% CI, 0.66 to 0.97; P = .02). A nonsignificant increase in OS was also observed for panitumumab-FOLFOX4 versus FOLFOX4 (median OS, 23.9 v 19.7 months, respectively; HR, 0.83; 95% CI, 0.67 to 1.02; P = .072). In the mutant KRAS stratum, PFS was significantly reduced in the panitumumab-FOLFOX4 arm versus the FOLFOX4 arm (HR, 1.29; 95% CI, 1.04 to 1.62; P = .02), and median OS was 15.5 months versus 19.3 months, respectively (HR, 1.24; 95% CI, 0.98 to 1.57; P = .068). Adverse event rates were generally comparable across arms with the exception of toxicities known to be associated with anti-EGFR therapy. Conclusion This study demonstrated that panitumumab-FOLFOX4 was well tolerated and significantly improved PFS in patients with WT KRAS tumors and underscores the importance of KRAS testing for patients with mCRC.

Purpose Panitumumab is a fully human anti–epidermal growth factor receptor (EGFR) monoclonal antibody that improves progression-free survival (PFS) in chemotherapy-refractory metastatic colorectal cancer (mCRC). This trial evaluated the efficacy and safety of panitumumab plus fluorouracil, leucovorin, and irinotecan (FOLFIRI) compared with FOLFIRI alone after failure of initial treatment for mCRC by tumor KRAS status. Patients and Methods Patients with mCRC, one prior chemotherapy regimen for mCRC, Eastern Cooperative Oncology Group performance status 0 to 2, and available tumor tissue for biomarker testing were randomly assigned 1:1 to panitumumab 6.0 mg/kg plus FOLFIRI versus FOLFIRI every 2 weeks. The coprimary end points of PFS and overall survival (OS) were independently tested and prospectively analyzed by KRAS status. Results From June 2006 to March 2008, 1,186 patients were randomly assigned 1:1 and received treatment. KRAS status was available for 91% of patients: 597 (55%) with wild-type (WT) KRAS tumors, and 486 (45%) with mutant (MT) KRAS tumors. In the WT KRAS subpopulation, when panitumumab was added to chemotherapy, a significant improvement in PFS was observed (hazard ratio [HR] = 0.73; 95% CI, 0.59 to 0.90; P = .004); median PFS was 5.9 months for panitumumab-FOLFIRI versus 3.9 months for FOLFIRI. A nonsignificant trend toward increased OS was observed; median OS was 14.5 months versus 12.5 months, respectively (HR = 0.85, 95% CI, 0.70 to 1.04; P = .12); response rate was improved to 35% versus 10% with the addition of panitumumab. In patients with MT KRAS, there was no difference in efficacy. Adverse event rates were generally comparable across arms with the exception of known toxicities associated with anti-EGFR therapy. Conclusion Panitumumab plus FOLFIRI significantly improved PFS and is well-tolerated as second-line treatment in patients with WT KRAS mCRC.

3536 Background: Biomarker analyses have shown that patients (pts) with RASwild-type (WT) mCRC can achieve overall survival (OS) benefits with first-line pmab plus chemotherapy. Other biomarkers ma...

731 Background: Biomarker analyses have shown that patients (pts) with RAS wild-type (WT) mCRC can achieve overall survival (OS) benefits with first-line pmab plus chemotherapy. Other biomarkers may exist that could optimize pt selection. Epidermal growth factor receptor ligand (eg AREG) levels have been correlated with OS during anti-EGFR therapy. Here we investigate the relationship between AREG expression and treatment outcome in a single-arm first-line mCRC study of pmab + FOLFIRI. Methods: Qualified reverse transcription quantitative polymerase chain reaction (RT-qPCR) assays were used to measure AREG RNA expression in archival formalin-fixed, paraffin embedded tumor samples from mCRC pts in two pmab trials (STEPP and 314). The STEPP analysis was used to establish a cut-off point in AREG expression that identified the best responders. This cut-off was applied prospectively to samples previously analyzed for KRAS in the 314 trial. Using the KRASMT subgroup as a non-responding comparator, Cox proportional hazards (PH) models were used to evaluate AREG expression levels as a continuous covariate. Decision curves were used to estimate the progression-free survival (PFS) hazard ratio (HR) with increasing levels of baseline AREG expression. Results: In the 314 trial 100 pts had evaluable AREG levels. Among 50 KRAS WT pts, high AREG expression was associated with objective response (OR) (Table). The high AREG group had better PFS HRs (KRAS WT/KRAS MT: 0.30 [95% CI, 0.12–0.75]) compared with the low AREG group (PFS HR 0.49 [95% CI 0.21–1.1]). There was a significant biomarker-by-AREG expression interaction in the Cox PH model (p=0.03). Conclusions: Treatment decision curves based on the PH model suggest that most KRAS WT patients express AREG at levels where treatment benefit is predicted. Future analysis of samples from a RASWT population may provide further insights. Clinical trial information: NCT00508404. [Table: see text]

520 Background: Global mCRC treatment guidelines for EGFR inhibitors require prior confirmation of wild-type RAS status (KRAS exons 2, 3, 4 and NRAS 2, 3, 4). The aim of this study was to estimate the prevalence of RAS mutations among mCRC patients by country, demographic characteristics, and clinical risk factors. A secondary aim was to estimate BRAF and KRASexon 2 mutation prevalence. Methods: Data from 5 published Amgen-sponsored randomized clinical trials (RCTs) were merged in a retrospective pooled analysis. There were 3 phase III, 1 phase II, and 1 phase Ib/II studies. For 4 out of 5 RCTs, RAStesting was conducted in a U.S. laboratory (Transgenomic Inc.) using Sanger sequencing on DNA extracted from tumor samples. For the remaining trial, a combination of next-generation sequencing and Sanger sequencing was used. Results: A total of 3,196 patients from 36 countries were included. The overall unadjusted prevalence of RAS mutations among mCRC subjects was 55.9% (95% CI, 53.9%, 57.9%); KRAS exon 2 mutation prevalence was 42.6% (40.7%, 44.5%). The prevalence by exon is given in the table below. BRAFmutation prevalence was 8.1% (6.7%, 9.6%). There were no statistically significant differences in RAS mutation prevalence by gender, age, or clinical factors such as performance status, tumour site, biopsy origin, or metastasis characteristics. Statistically significant differences in RAS mutation prevalence estimates were observed by country and by region with rates for Central West Europe being significantly lower than Eastern Europe (49.4% [44.4%, 54.3%] and 61.5%; [55.3%; 67.4%] respectively). Statistically significant RASmutation prevalence differences were observed between studies which could be due to varying patient characteristics. Conclusions: By merging data from RCTs, the analysis provides robust estimates of RASmutation prevalence. Studies using observational data are needed to confirm these findings. [Table: see text]

694 Background: Pmab, R, and G are fully human monoclonal antibodies that target EGFR, HGF, and IGF-1R, respectively. In part 2 of this 3-part study in previously treated pts with wild-type (WT) KRAS mCRC, pmab+R met the pre-specified criterion for improvement in objective response rate (ORR) whereas pmab+G did not. We report an exploratory analysis of the treatment effect of pmab, R, and G in pts with activating RAS mutations beyond KRAS exon 2. Methods: Part 2 was a phase II, randomized, double-blinded trial of pmab+R or pmab+G vs. pmab+placebo, administered Q2W until disease progression or intolerance. The primary endpoint was ORR. Secondary endpoints included overall survival (OS), progression-free survival (PFS), and safety. Mutations in KRAS exon 3 (codons 59/61) and exon 4 (codons 117/146); NRAS exon 2 (codons 12/13), exon 3 (codons 59/61), and exon 4 (codons 117/146); and BRAF exon 15 (codon 600) were detected by bidirectional Sanger sequencing. Results: Of 142 pts randomized, 92 (65%) were evaluable for RAS. Of 92 evaluable pts, 79 (86%) were WT RAS (WT in KRAS and NRAS exons 2, 3, and 4) and 13 (14%) had RAS mutations beyond KRAS exon 2 (mutant in any KRAS exon 3 or 4 or NRAS exon 2, 3, or 4). None of the pts with RAS mutations had an objective response (Table). Of 93 pts evaluable for BRAF, 7 (8%) had V600E mutations (all 7 were WT RAS). Two pts with BRAF V600E tumors had a partial response and were in the pmab+R arm (n=3). No new safety signals were identified. Conclusions: In this small, retrospective study, ORR, PFS and OS were similar between the arms of R or G plus pmab vs pmab alone in pts with WT RAS mCRC tumors. Our findings indicate that RAS mutations beyond KRAS exon 2 impact ORR, PFS, and OS. Clinical trial information: NCT00788957. [Table: see text]

3568 Background: Previously, extended RAS analysis from this study showed a trend toward improvements in HR on OS and PFS with pmab + FOLFIRI vs FOLFIRI in WT RAS group vs WT KRAS exon 2 group. Her...

4048 Background: Estimates of the frequency of genomic alterations in MET and HER2 in gastric cancer vary widely, but alterations in MET are generally less common than alterations in HER2. We exami...

LBA387 Background: Previously, this study showed significant improvement in progression-free survival (PFS) in pmab + FOLFIRI vs FOLFIRI (HR=0.73; 95% CI: 0.59-0.90; p=0.004) and a trend toward improved overall survival (OS; HR=0.85; 95% CI: 0.70-1.04; P=0.12; Peeters et al. JCO 2010). Recently, analysis from 1st-line mCRC PRIME study showed that mutations in RAS genes (KRAS/NRAS exons 2/3/4) predicted a lack of response to pmab (Douillard et al. NEJM 2013). Methods: The primary objective was to assess the tx effect of pmab + FOLFIRI vs FOLFIRI on OS and PFS based on RAS mutation status in the primary analysis population. Bidirectional Sanger sequencing was used to detect mutations in KRAS exons 3, 4 and NRAS exons 2, 3, 4 in patients (pts) with known WT KRAS exon 2 mCRC. Results: In this prospective retrospective analysis, overall RAS ascertainment rate was 85% (n=1008/1186). 18% of the WT KRAS exon 2 pts harbored additional RAS mutations (n=107/597). Efficacy is shown (Table). Tx HR for pts with WT RAS was 0.803 (95% CI: 0.629-1.024; P=0.077) for OS and 0.695 (95% CI: 0.536-0.903; P=0.006) for PFS. Conclusions: Improvements were observed in the tx effect of pmab + FOLFIRI vs FOLFIRI on OS and PFS in the WT RAS group vs the WT KRAS exon 2 group. Pts with MT RAS mCRC are unlikely to benefit by the addition of pmab to FOLFIRI, similar to pts with MT KRAS exon 2 mCRC in this study. These findings are consistent with previously reported outcomes by RAS status and support RAS testing to determine potentially appropriate pts for pmab tx. Clinical trial information: NCT00339183. [Table: see text]

3617 Background: An exploratory biomarker analysis of the randomized, phase 3 monotherapy 20020408 study of pmab vs best supportive care (BSC) demonstrated that mutations in KRAS exon 3 and NRAS exons 2 and 3 appeared to be predictive of pmab response (Peeters et al, 2013). We expanded these results to determine whether mutations in exon 4 of the KRAS and NRAS genes are predictive for pmab treatment and to determine the treatment effect in the overall wild-type (WT) KRAS and NRAS population. Methods: Using a combination of Next Generation Sequencing, Sanger Sequencing, and WAVE-based SURVEYOR Scan Kits from Transgenomic, archival patient tumors were examined for mutations in KRAS and NRAS exon 4. These data were combined with previously presented data from KRAS and NRAS exon 2 and 3 analyses for evaluation of the comprehensive WT KRAS and NRAS subgroup. Results: 9/243 (3.7%) and 2/243 (0.8%) patient tumors with WT KRAS exon 2 status harbored a mutation in KRAS or NRAS exon 4, respectively. One tumor had mutations in both KRAS and NRAS exon 4. In the pmab arm, patients with WT KRAS and WT NRAS tumor status had an objective response rate (ORR) of 15% (11/72) whereas patients with mutant (MT) KRAS or MT NRAS tumor status had an ORR of 1% (1/95; 1 patient with MT KRAS exon 4 had a partial response). There were no responses in the BSC arm regardless of the tumor status. In this analysis set, the treatment hazard ratio (HR; pmab:BSC) for progression-free survival (PFS) in the WT KRAS and WT NRAS subgroup was 0.38 (95% CI: 0.27 - 0.56), and in the MT KRAS or MT NRAS subgroup was 0.98 (95% CI: 0.73 - 1.31). The original WT KRAS exon 2 subgroup PFS HR was 0.45 (95% CI: 0.34 - 0.59) (Amado et al, 2007). Conclusions: This exploratory analysis suggests that mutations in KRAS and NRAS exon 4 occur in a small, but meaningful percentage of patients with mCRC. Extending previous findings from this study in patients with MT KRAS and/or MT NRAS exon 2 and/or 3 tumors, patients with MT KRAS and/or MT NRAS exon 4 tumors do not appear to benefit from pmab therapy. Clinical trial information: NCT00113763.

6029 Background: PARTNER was a multicenter, randomized phase II estimation study evaluating 1stEline tx of R/M SCCHN with doc/cis ± pmab. Methods: Patients (pts) were randomized 1:1 to doc/cis with pmab (Arm 1) or doc/cis alone (Arm 2). Arm 1 received 9 mg/kg pmab on day 1 of each 21-day cycle, and all pts received 1stEline doc/cis both at 75 mg/m2 on day 1 for up to 6 cycles. In Arm 1, pts could receive pmab monotherapy upon completion of 6 cycles of doc/cis until disease progression (PD). In Arm 2, pts could receive pmab as 2ndEline monotherapy upon PD. The primary endpoint was progression-free survival (PFS); secondary endpoints included overall survival (OS), objective response rate (ORR), and safety. HPV status was determined using p16 INK IHC. No formal hypothesis was tested. Results: Baseline characteristics were balanced between arms. Of 103 pts, HPV status was evaluable in 66 (64%); 29% were HPV positive. Efficacy results are shown (Table). Worst grade 3/4 adverse events (AEs) were 73% in Arm 1 vs 56% in Arm 2. Conclusions: Median PFS was increased in both arms over historical doublet cytotoxic chemotherapy. PFS and ORR were higher in the pmab arm in the overall population, in the HPV positive (n=19) group, and in the HPV negative (n=47) group. There was an increase in grade 3/4 AEs with this regimen. The crossover design, with 57% of Arm 2 pts receiving pmab as 2ndEline monotherapy, confounds interpretation of OS. Clinical trial information: NCT00454779. [Table: see text]

3511 Background: Analysis of a phase III pmab monotherapy study indicated that KRAS and NRAS mutations beyond KRAS exon 2 may be predictive of pmab efficacy (Peeters et al, 2013). Methods: The primary objective of this prospectively defined retrospective analysis of PRIME was to assess the effect of pmab + FOLFOX vs FOLFOX on overall survival (OS) in pts with mCRC based on RAS (KRAS or NRAS) or BRAF mutation status. "Gold standard" bidirectional Sanger sequencing and WAVE-based SURVEYOR Scan Kits from Transgenomic (conducted independently) were used to detect mutations in KRAS exon 3, exon 4; NRAS exon 2, exon 3, exon 4; and BRAF exon 15. Results: RAS ascertainment rate was 90%. Tx HRs for pts with WT RAS were 0.78 (95% CI, 0.62 - 0.99; p = 0.04) for OS (median gain of 5.8 months in the pmab arm) and 0.72 (95% CI, 0.58 - 0.90; p = < 0.01) for PFS. Tx HRs for WT KRAS exon 2/mutant (MT) other RAS were 1.29 (95% CI, 0.79 - 2.10; p = 0.31) for OS and 1.28 (95% CI, 0.79 - 2.07; p = 0.32) for PFS. Tx HRs for pts with WT or MT BRAF were inconsistent with a predictive biomarker (Table). Prognostic effects of the tested biomarkers will be presented. Conclusions: A statistically significant OS benefit was observed in pts with WT RAS mCRC treated with pmab + FOLFOX vs FOLFOX. Pmab is unlikely to benefit pts with any RAS mutations. In this analysis, BRAF mutation had no predictive value. Clinical trial information: NCT00364013. [Table: see text]

3631 Background: PEAK estimated the tx effect of FOLFOX6 with pmab or bev in 1st-line WT KRAS mCRC. The PRIME study showed significantly improved progression free survival (PFS) and overall survival (OS) with pmab + FOLFOX vs FOLFOX in pts with WT RAS (KRAS/NRAS exons 2, 3, 4) mCRC in a prospective-retrospective analysis (unpublished data). Methods: This prospective-retrospective analysis of PEAK was designed to assess the effect of pmab + FOLFOX6 or bev + FOLFOX6 on PFS (primary endpoint) and OS in WT RAS (KRAS/NRAS exons 2, 3, 4) mCRC. Pts were required to have WT KRAS exon 2 tumors. Bidirectional Sanger sequencing and Transgenomic SURVEYOR/WAVE analysis were independently conducted to detect mutations in KRAS exon 3 (codons 59/61), exon 4 (codons 117/146); NRAS exon 2 (codons 12/13), exon 3 (codons 59/61), exon 4 (codons 117/146); BRAF exon 15 (codon 600) in banked specimens. Results: 285 WT KRAS (exon 2) mCRC patients (pts) were randomized, 278 received tx. The current RAS ascertainment rate is 75%. Tx HRs (pmab:bev) for pts with WT RAS were 0.63 (95% CI, 0.43-0.94; p = 0.02) for PFS and 0.55 (95% CI, 0.30-1.01; p = 0.06) for OS (Table). The incidence of worst grade 3-5 adverse events was consistent with the primary analysis. Updated OS and BRAF results will be presented. Conclusions: In this 1st-line estimation study in WT RAS mCRC, PFS and OS HR favored pmab + FOLFOX6 relative to bev + FOLFOX6, suggesting that activating RAS mutations appear to be predictive for pmab tx effect. The safety profile for both arms was consistent with previously reported studies. Clinical trial information: NCT00819780. [Table: see text]

4005 Background: R is an investigational, fully human, monoclonal antibody to HGF/SF, the ligand of the MET receptor. A double-blind, P-controlled, phase 2 study randomized 121 G/EGJ cancer pts 1:1:1 to 15 mg/kg R + ECX (Arm A, n = 40), 7.5 mg/kg R + ECX (Arm B, n = 42), or P + ECX (Arm C, n = 39). OS and PFS improved with the addition of R to ECX (Iveson et al, European Multidisciplinary Cancer Congress 2011; abstr 6.504). High tumor MET levels have been associated with poor prognosis in G cancer (Nakajima et al, Cancer 1999;85:1894-1902). We explored MET pathway biomarkers to identify pts who may benefit from R. Methods: MET protein levels and gene copy numbers were measured in archival tumor samples by immunohistochemistry (IHC) and fluorescence in situ hybridization, respectively. High and low MET subgroups were defined by several predefined strategies. Total HGF and soluble MET (sMET) protein in plasma were measured by ELISA and MSD assays, respectively. Treatment and biomarker effects on OS and PFS were analyzed by Cox proportional hazard models and Kaplan-Meier estimates. Results: Tumor samples were evaluable for MET protein from 62 pts in Arms A + B and 28 pts in Arm C. Pts with METHigh tumors (> 50% tumor cells positive) in Arms A + B had improved median OS than those in Arm C (11.1 mo [80% CI: 9.2-13.3] vs 5.7 mo [80% CI: 4.5-10.4]; HR = 0.29, 95% CI: 0.11-0.76, p = 0.012). Conversely, pts with METLow tumors (≤ 50% positive) in Arms A + B had a trend toward unfavorable OS compared with those in Arm C (HR = 1.84, 95% CI: 0.78-4.34). In the chemotherapy only arm (Arm C), pts with METHigh tumors had poorer OS (HR = 3.22, 95% CI: 1.08-9.63) than pts with METLow tumors. Similar trends were seen with PFS. Predefined dichotomization schemes for tumor MET gene copy number and baseline plasma levels of total HGF or sMET did not correlate with OS or PFS. Conclusions: High MET expression by IHC may predict clinical benefit to R + ECX in G/EGJ cancer pts. High MET expression may also be associated with poor prognosis for ECX-treated pts. Further investigation is needed to confirm these findings.

2535 Background: R is an investigational, fully human monoclonal antibody to hepatocyte growth factor/scatter factor (HGF/SF), the only known MET receptor ligand. In a double-blind, placebo-controlled, phase 2 trial of 121 pts with G/EGJ cancer, R (7.5 or 15 mg/kg) + ECX showed trends for improved overall survival (OS) and progression-free survival (PFS) compared to ECX alone (placebo, P). Methods: E-R analyses were performed using pharmacokinetic (PK), biomarker, efficacy, and safety data. A population PK model was used to evaluate covariate effects (eg, demographics, ECX, and MET status) on R PK and predict individual R exposure (trough steady-state Cmin [C]). The effect of C on OS/PFS was evaluated with Kaplan-Meier estimates and Cox proportional hazards models. Covariate effects for OS/PFS were evaluated with multivariate analysis. The relationships between adverse events of interest (AEs), lab values, and C were analyzed with descriptive statistics and linear regression models. Results: R showed linear PKs that were unaffected by ECX or MET levels. Pts who received R + ECX were divided into low C (CL) and high C (CH) groups by the median C (94 µg/mL). Median PFS was 4.2, 4.5, and 6.9 months in the P, CL, and CH groups; median OS was 8.9, 9.5, and 13.3 months. Improved OS/PFS in CH and improved PFS in CH and CL groups (vs P) were seen after adjusting for baseline covariates. Pts with tumors that expressed high MET levels (METHigh: > 50% cells positive) showed greater improvement in OS in the CH vs CL group. No improvement in OS was seen in METLow pts (CH and CL groups) compared to placebo (see Table). No relationship was seen between R exposure and AEs or lab values. Conclusions: Higher R exposure was associated with improved OS/PFS in METHigh pts without increased toxicity, supporting further study of R + ECX in G/EGJ cancer. [Table: see text]

2594 Background: R is an investigational, fully human monoclonal antibody to hepatocyte growth factor/scatter factor (HGF/SF) that inhibits signaling though the MET receptor. In a double-blind, placebo-controlled, phase 2 trial of 121 patients with G/EGJ cancer, R (7.5 or 15 mg/kg) + ECX showed trends for improved progression-free survival (PFS) and overall survival compared to ECX alone. The combined effects of R and ECX on tumor reduction and PFS were modeled using the phase 2 data. Methods: A population pharmacokinetic (PK) model was used to estimate R PK parameters and individual R concentrations (C) over time. A tumor dynamic model was developed to characterize the combined effects of R with ECX on tumor growth and cell death and to evaluate the impact of baseline patient characteristics and lab values on model parameters. A discrete time-survival model was developed with PFS and C data to evaluate the effect of R, ECX, and the interaction between R and ECX on PFS within a given time interval. Results: R exhibited linear PKs with an estimated mean clearance of 0.216 L/d/70 kg. The tumor dynamic model suggested that R and ECX worked jointly to reduce tumor size from baseline via inhibition of the tumor growth rate constant (Kgrowth) and stimulation of the death rate of tumor cells (Kdeath). Assuming the maximal inhibition of Kgrowth is 100%, the estimated mean C that provided 50% maximal Kgrowth inhibition (EC50) was 6.71 µg/mL. The mean (SD) estimated effect of 7.5 and 15 mg/kg R on Kgrowth was 90.1% (3.8%) and 95.5% (1.9%) inhibition, respectively. None of the tested baseline factors appeared to significantly affect tumor reduction by R + ECX. In the discrete time-survival model, the R and ECX combination significantly improved PFS, and the model suggests that the magnitude of the effect of one treatment was dependent on the other. Conclusions: R and ECX appeared to work in combination to decrease tumor size and to improve PFS.

5504^ Background: SPECTRUM evaluated the safety and efficacy of pmab, a fully human monoclonal antibody against the epidermal growth factor receptor, with platinum‑based chemotherapy (CT) vs CT alone in patients (pts) with R/M SCCHN. This predefined analysis presents outcomes by tumor HPV status. Methods: All tumor samples were centrally reviewed. HPV status was determined using a validated immunohistochemistry assay to p16INK4A by an independent lab blinded to treatment assignments. Tumor samples were scored positive or negative according to prespecified criteria. Results: Of 657 enrolled pts (ITT), 443 (67%) had samples evaluable for HPV testing. Ninety‑nine (22%) tumors were HPV+ and 344 (78%) were HPV-. HPV+ rates varied by site (37% oropharynx, 19% larynx, 15% oral cavity, and 13% hypopharynx) and geographic region (44% N America, 22% W Europe, 21% Asia Pacific, 19% S America, and 18% E Europe). Demographics were generally balanced except pts with HPV+ vs HPV- tumors were more often non‑smokers (31% vs 14%), had oropharyngeal tumors (47% vs 23%), and had poorly differentiated tumors (30% vs 13%). Efficacy results are shown (Table). Adverse events were generally balanced between HPV+ and HPV- pts. Conclusions: Pts with HPV- R/M SCCHN administered pmab + CT had improved overall survival (OS) and progression‑free survival (PFS), whereas no improvement in OS or PFS was observed in pts with HPV+ tumors. [Table: see text]

3530 Background: KRAS mutation is an established biomarker for lack of response to antiepidermal growth factor receptor (EGFR) antibodies in mCRC. We used next generation sequencing to investigate ...

3500 Background: Pmab, ril, and gan are fully human monoclonal antibodies against epidermal growth factor receptor, hepatocyte growth factor, and insulin-like growth factor receptor 1, respectively. This 3-part study examined the safety and efficacy of ril or gan with pmab in pts with mCRC expressing WT KRAS. Methods: Part 2 was a phase II, randomized, double-blinded, placebo-controlled trial of pmab (6 mg/kg) + placebo (Arm 1) vs pmab + ril (10 mg/kg, Arm 2) vs pmab + gan (12 mg/kg, Arm 3), all administered Q2W until disease progression or intolerance. Pts were ≥ 18 yrs old, had ECOG PS 0/1, and prior irinotecan and/or oxaliplatin. The primary endpoint for Part 2 was objective response rate (ORR). A Bayesian approach was undertaken to determine a meaningful improvement in ORR in the combination arms. Secondary endpoints included progression-free survival (PFS) and safety (adverse events [AEs]). Biomarker analyses including c-Met expression by immunohistochemistry (IHC) on archival tumor samples were comp...

5509 Background: HGF is a hypoxia induced protein that binds to its receptor MET to regulate expression of a variety of molecules including the cytokine IL-8. Both HGF and IL-8 are associated with ...