Citations

3526 Background: Prior observational studies have suggested that smoking is associated with poorer overall survival after colon cancer (CC) diagnosis. Using data from N0147, a phase III randomized adjuvant trial of patients with stage III CC, we assessed the relationship between smoking status and cancer outcomes (disease-free survival (DFS) and time to recurrence (TTR)), accounting for possible heterogeneity by patient and tumor characteristics. Methods: Patients completed a risk factor questionnaire at baseline prior to randomization to FOLFOX or FOLFOX+cetuximab (N=1968). Information was collected on smoking and other lifestyle factors, including alcohol consumption, body mass index (BMI), and physical activity. Multivariate Cox models assessed the association between smoking history and the primary trial outcome of DFS, as well TTR, adjusting for other lifestyle and clinical factors. The median follow-up was 3.5 years. Results: Overall, 52% of patients were former or current smokers. Compared to never smokers, ever smokers experienced significantly shorter DFS [3-year DFS: 70% vs 74%, hazard ratio (HR)=1.21, 95% confidence interval (CI): 1.02-1.42]. This association persisted after adjusting for age, sex, tumor subsite, number of nodes involved, T-stage, mismatch repair deficiency, BRAF mutation status, performance score, physical activity, BMI, and alcohol consumption (HR=1.23, 95% CI: 1.02-1.49). There was significant interaction in this association by BRAF mutation status (p=0.02): smoking was associated with shorter DFS in BRAF wildtype CC patients (HR=1.25, 95% CI: 1.04-1.51) but not in BRAF mutant CC patients (HR=0.72, 95% CI: 0.47-1.10). Patterns of association with smoking, overall and by BRAF status, were identical in analyses of TTR. Conclusions: Overall, smoking was significantly associated with shorter DFS and TTR in CC patients. These adverse relationships were most evident in patients with BRAF wildtype CC.

3639 Background: The first phase of the multi-center prospectively specified retrospective study Validating Indicators To Associate Recurrence (VITAR), assessing the relationship between GCC gene expression in formalin fixed (FFPE) LNs and time to recurrence (TTR) in stage II CC pts not treated with adjuvant chemotherapy (Sargent, Annals Surg Onc 2011), showed promising initial results. Here we report a validation set of 463 new stage II CC pts. Methods: GCC mRNA was quantified by RT-qPCR using FFPE LNs from untreated T3N0 CC pts diagnosed from 1999-2008 with at least 12 LNs examined , blinded to clinical outcomes. Patients were classified by GCC LN ratio (LNR) (high risk: LNR > 0.1; low risk: LNR ≤ 0.1), with LNR defined as ratio of GCC positive to GCC informative LNs. Cox regression models tested the relationship between GCC and the primary endpoint of TTR, adjusted for age, tumor grade, number of LN examined pathologically, and lymphovascular invasion. Mismatch repair (MMR) status was also assessed. All primary analyses and cut-points were pre-specified. Results: 46pts (10%) recurred (rec), median follow-up was 65 months, median LNs examined was 20, and 42% (195/463) were classified high risk. Overall, TTR was not significantly associated with binary GCC LNR risk class (HR=1.47, p=.208) or DFS (HR= 1.39, p=.097). One site’s (n=97) tissue grossing method precluded appropriate LN assessment with existing GCC qualification methods. Excluding this site resulted in a TTR HR=1.91, p=0.051 (multivariate). In a post-hocanalysis excluding this site and using a 3-level GCC risk group of high (LNR > 0.20), intermediate (0.10 < LNR < 0.20) and low (LNR < 0.10), high risk group pts had a 5-yr rec risk of 22% versus 8% in low risk (HR 2.72, p=0.006). MMR status was not significantly associated with TTR (multivariate p=0.30). Conclusions: GCC status is a promising prognostic factor in appropriately staged stage II CC pts not treated with adjuvant therapy independent of traditional histopathology risk factors, but GCC determination must be performed with methodology adapted to the tissue procurement and fixation technique. Outcome associations were strengthened when considering a 3-level GCC categorization.

3576 Background: BRAF encodes a serine-threonine kinase that is a downstream effector of activated RAS. A point mutation (V600E) in BRAF occurs in a subset of colorectal cancers (CRCs) and is associated with adverse outcome and may predict non response to anti-EGFR antibodies. Detection of a BRAFV600E mutation in a CRC with microsatellite instability indicates a sporadic origin and excludes Lynch Syndrome. While BRAFV600E mutation status is determined using a DNA-based assay, antibodies against the BRAFV600E protein have recently been developed. We examined mutant BRAFV600E protein expression and its concordance with mutation status. Methods: Primary stage III colon carcinomas (50 BRAFV600E mutation carriers and 25 wild-type cases) were studied from a completed phase III adjuvant trial comparing FOLFOX +/- cetuximab (NCCTG N0147). In archival resection specimens, immunohistochemistry (IHC) was performed using a pan-BRAF antibody and a V600E mutation-specific antibody raised against an immunogenic synthetic peptide derived from the internal region of the BRAFV600E protein. BRAFV600E mutations in codon 15 were analyzed in extracted DNA using a multiplex, allele specific PCR–based assay. BRAF staining was scored independently by two pathologists blinded to mutation status. Results: In primary colon carcinomas stained with a pan-BRAF antibody, diffuse cytoplasmic staining for BRAF proteins was detected in 74 of 75 carcinomas with one case deemed non-evaluable. Using the mutation-specific BRAFV600E antibody, diffuse cytoplasmic staining was detected in 49 of 74 tumors without appreciable heterogeneity of expression. Among these 49 tumors expressing mutant BRAFV600E proteins, all (100%) were found to carry a BRAFV600E mutation according to a DNA-based assay. In contrast, absent BRAFV600E staining was observed in all 25 tumors that were found to have wild-type copies of BRAFV600E detected using a PCR-based assay. Conclusions: For the detection of mutant BRAFV600E, complete concordance was found between IHC and a DNA-based method in colon carcinomas. This finding supports the use of IHC as a simplified strategy to screen CRCs for mutant BRAFV600E proteins in routine clinical practice to inform clinical decision-making.

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.

4075 Background: EAC recurrence after surgery with curative intent is believed to carry a uniformly dismal prognosis that may discourage further therapy. To date, the post-recurrence survival of patients has not been examined in EAC. Our aim was to examine site of recurrence in relation to outcome in EAC patients after surgery. Methods: Among EAC patients (N = 796) rendered margin-free at surgery performed at Mayo Clinic, most were T3-4 and lymph node (LN)-positive; none received neoadjuvant therapy. The patient subset who had documented disease recurrence (N = 401) formed the current study population. Cox models were used to examine overall survival (OS) post-recurrence. Results: Among patients with recurrence, median time to recurrence (TTR) was 11 months. Site of recurrence included loco-regional (regional LNs, esophagogastric, anastomosis), chest, abdomen, or distant sites in 97 (27%), 144 (40%), 181 (50%), and 88 (24%) patients, respectively. Most recurrences (66%) were limited to one site. Chest-involved recurrence was significantly associated with improved OS (hazard ratio [HR] 0.78, P = .047), even after adjusting for TTR, number of recurrence sites, tumor pathology, and palliative chemotherapy. This result was confirmed when multivariate analysis was restricted to patients who had only 1 recurrence site (Table) or who had biopsy-proven recurrence (P = .080). In separate models, abdomen-involved (HR = 1.3, P = .016) or bone-involved (HR = 1.6, P= .008) recurrences were independently associated with worse OS. Conclusions: Chest-involved recurrence of EAC independently predicts for improved survival, whereas abdominal and bony sites of recurrence predict for worse outcome. Primary tumor grade and node number were durable prognosticators after recurrence. These novel data provide useful prognostic information and have the potential to influence clinical decision-making. [Table: see text]

4009 Background: HER2 expression in upper digestive cancer is reported to be heterogeneous, which substantially affects interpretation of HER2 positivity in the clinic. Yet the frequency and prognostic impact of HER2 genetic heterogeneity and polysomy 17 (poly17) are unknown in EAC. Methods: HER2 amplification (fluorescence in situ hybridization) and protein expression were examined in untreated surgical EAC specimens (N = 661) at Mayo Clinic. HER2 genetic heterogeneity was defined per ASCO/CAP as amplification (HER2/CEP17 ratio ≥ 2) in 5-50% of cancer cells; poly17 refers to ≥ 3 copies of chromosome 17. Most tumors were T3-4 (68%) or lymph node (LN)-positive (73%). Cox models were used to assess disease-specific (DSS) and overall survival (OS). Results: HER2 amplification was detected in 117 of 661 EACs (18%), of which 20 (17%) showed HER2 heterogeneity. HER2 heterogeneous tumors had a significantly higher frequency of poly17 and high tumor grade. HER2 heterogeneity by amplification vs expression were correlated. Since heterogeneity was limited to HER2-amplified tumors, survival analysis was stratified by amplification status. In multivariable analysis, only HER2 heterogeneity and metastatic LN number were prognostic (Table). Conclusions: Among HER2 amplified EACs, 17% show HER2 heterogeneity, which is associated with increased poly17 and independently predicts 2-fold higher risk of cancer-specific death. Among HER2-nonamplified cases, poly17 is independently associated with worse survival. These novel findings demonstrate aggressive subgroups in HER2-amplified and -nonamplified EACs that have important implications for HER2 analysis and evaluation of benefit from HER2 targeted therapy. [Table: see text]

3564 Background: Lethal-7 (let-7) microRNA has been shown to inhibit colon cancer cell proliferation by inducing KRAS downregulation after binding to specific sites in the 3’- UTR. Recent studies identified a KRAS 3’-UTR polymorphism in the let-7 complimentary site (LCS6) that has been shown to weaken let-7 binding and alter KRAS expression. Carriers of the LCS6 G-allele showed worse survival in metastatic colorectal cancer from prior studies of limited sample size. In the current study, we evaluated the LCS6 variant in 2,834 Stage III colon cancer patients and its association with disease-free survival (DFS), KRAS mutation status, and other clinicopathological features. Methods: In the NCCTG phase III trial (N0147), the LCS6 variant was assayed in germline DNA extracted from whole blood using RT-PCR. Extracted tumor DNA was analyzed for KRAS exon 2 mutations. Chi-squared and two-sample t test were used to compare baseline factors and KRAS mutation status between patients defined by LCS6 variant status. Log-rank tests and multivariate Cox models assessed the unadjusted and adjusted associations between LCS6 status and DFS, respectively. Results: We identified 432 (15.2%) patients heterozygous or homozygous for the LCS6 G-allele and 2402 (84.8%) patients homozygous for the LCS6 T-allele. G-allele carriers were significantly more frequent in Caucasians than other races (Chi-Squared Test, p<0.0001). No associations were found between the LCS6 genotype and T stage, positive lymph node number, tumor differentiation, or primary tumor location (all p>0.2). Moreover, the LCS6 genotype was not associated with DFS (hazard ratio = 0.93, p=0.49) even after combining LCS6 genotype with KRAS mutation status. Conclusions: We report the largest association study investigating the LCS6 polymorphism and colon cancer outcome. There is no significant evidence that the germline LCS6 genotype was associated with DFS in stage III colon cancer patients. Additional studies are needed to determine if LCS6 genotype differs between tumor and germline DNA which may further clarify its prognostic value.

PURPOSE The Fast Healthcare Interoperability Resources (FHIR) is emerging as a next-generation standards framework developed by HL7 for exchanging electronic health care data. The modeling capability of FHIR in standardizing cancer data has been gaining increasing attention by the cancer research informatics community. However, few studies have been conducted to examine the capability of FHIR in electronic data capture (EDC) applications for effective cancer clinical trials. The objective of this study was to design, develop, and evaluate an FHIR-based method that enables the automation of the case report forms (CRFs) population for cancer clinical trials using real-world electronic health records (EHRs). MATERIALS AND METHODS We developed an FHIR-based computational pipeline of EDC with a case study for modeling colorectal cancer trials. We first leveraged an existing FHIR-based cancer profile to represent EHR data of patients with colorectal cancer, and then we used the FHIR Questionnaire and QuestionnaireResponse resources to represent the CRFs and their data population. To test the accuracy of and overall quality of the computational pipeline, we used synoptic reports of 287 Mayo Clinic patients with colorectal cancer from 2013 to 2019 with standard measures of precision, recall, and F1 score. RESULTS Using the computational pipeline, a total of 1,037 synoptic reports were successfully converted as the instances of the FHIR-based cancer profile. The average accuracy for converting all data elements (excluding tumor perforation) of the cancer profile was 0.99, using 200 randomly selected records. The average F1 score for populating nine questions of the CRFs in a real-world colorectal cancer trial was 0.95, using 100 randomly selected records. CONCLUSION We demonstrated that it is feasible to populate CRFs with EHR data in an automated manner with satisfactory performance. The outcome of the study provides helpful insight into future directions in implementing FHIR-based EDC applications for modern cancer clinical trials.

PURPOSE The microsatellite instability (MSI) or deficient mismatch repair (dMMR) phenotype is usually regarded as a single biologic entity, given the absence of comparative analyses regarding prognosis and response to chemotherapy between sporadic and familial dMMR cancers. PATIENTS AND METHODS Patients with stage III colon cancers were randomly assigned to FOLFOX (leucovorin, fluorouracil, and oxaliplatin) with or without cetuximab in 2 large adjuvant phase III trials (N = 5,577). Among patients with MSI and KRAS exon 2 wild-type (WT) tumors, the prognostic and predictive impacts of sporadic versus familial dMMR cancers and BRAF V600E mutational status were determined. Multivariable Cox proportional hazards models were used to assess disease-free survival (DFS) by treatment arm, adjusting for age, sex, tumor grade, Eastern Cooperative Oncology Group performance status, pT/pN stage, and primary tumor location. RESULTS Among patients with MSI status with complete data for dMMR mechanism analysis (n = 354), 255 (72%) had sporadic ( BRAF mutation and/or MLH1 methylation) and 99 (28%) had familial tumors ( BRAF WT and unmethylated MLH1 or loss of MSH2/MSH6/PMS2 protein expression). A large proportion of dMMR sporadic tumors were mutated for BRAF (n = 200). In patients treated with FOLFOX, DFS did not differ statistically by dMMR mechanism, whereas in patients treated with FOLFOX plus cetuximab, those with sporadic tumors had worse DFS than those with familial cancers (multivariable hazard ratio, 2.69; 95% CI, 1.02 to 7.08; P = .04). Considering the predictive utility, the interaction between treatment and dMMR mechanism was significant ( P = .03). Furthermore, a nonsignificant trend toward a deleterious effect of adding cetuximab to FOLFOX was observed in patients with BRAF-mutant but not BRAF WT tumors. CONCLUSION The addition of cetuximab to adjuvant FOLFOX was associated with shorter DFS in patients with sporadic dMMR colon cancer. Additional studies are needed to validate these results in metastatic disease.