bluuebunny/crossref_metadata_2025 huggingface dataset:
A phase II study of GVAX colon vaccine with cyclophosphamide and pembrolizumab in patients with mismatch repair–proficient (MMR-p) advanced colorectal cancer.
Authors: Yarchoan Mark , Ferguson Anna K. , Durham Jennifer N. , Rozich Noah , Rodriguez Christina , Huang Chiung-Yu , Browner Ilene S. , De Jesus-Acosta Ana , Le Dung T. , Laheru Dan , Donehower Ross C. , Jaffee Elizabeth M. , Zheng Lei , Azad Nilofer Saba
Published: January 2019

563

Background: Mismatch repair proficient (MMRp) colorectal cancer (CRC) is refractory to single-agent programmed cell death protein 1 (PD1) inhibitors. Cancer vaccines may prime the tumor microenvironment for anti-PD1 therapy. Colon GVAX is an allogeneic, whole-cell, GM-CSF-secreting vaccine that induces T-cell immunity against tumor-associated antigens. GVAX has previously been studied in combination with low-dose cyclophosphamide (Cy) to inhibit regulatory T cells. Methods: We conducted an open label, single-arm, phase 2 study of GVAX/Cy in combination with the PD1 inhibitor pembrolizumab in patients with MMRp CRC who had received at least two prior lines of therapy in the metastatic setting. Patients received pembrolizumab plus Cy on day 1, GVAX on day 2, of a 21 day cycle through 4 cycles, and were then continued on a maintenance regimen of pembolizumab every 3 weeks with cy/GVAX given every 12 weeks. Results: Seventeen patients were enrolled. There were no objective responses, and the disease control rate was 18% by RECIST and 29% by irRC. The median progression free survival was 2.7 months and the median overall survival was 7.0 months. Biochemical responses (≥30% decline in CEA) were observed in 7/17 (41%) of patients. Two patients (12%) had grade 3/4 adverse events that were attributed to study therapy. To test the hypothesis that the induction of a humoral response against CEA protein had resulted in the observed biochemical responses, we measured patient titers of anti-CEA antibodies. Anti-CEA antibody titers increased 13 of 13 patients (100%) with available paired pre- and on-treatment research blood samples, but the change in anti-CEA antibody titers were similar among CEA responders and non-responders. Multiplex immunohistochemistry performed on pre- and post- biopsy specimens will be reported at the conference. Conclusions: GVAX/Cy plus pembrolizumab is well tolerated in advanced MMRp CRC and resulted in CEA responses but not radiographic responses. PFS and OS compare favorably to historical controls in this small cohort. CEA responses were not observed with PD1 monotherapy in MMRp CRC, suggesting GVAX can modulate the antitumor immune response. Clinical trial information: NCT02981524.
MACC1 expression as a candidate prognostic biomarker in colorectal cancer patients receiving adjuvant oxaliplatin-based therapy.
Authors: Symonds Lynn Katherine , Baker Kelsey K. , Redman Mary Weber , Koch Lisa , Carter Kelly , Yu Ming , Wirtz Ralph , Poulios Christos , Pentheroudakis George E. , Papaxoinis George , Pectasides Dimitrios G. , Kalogeras Konstantine T. , Fountzilas George , Grady William M. , Cohen Stacey
Published: January 2019

567

Background: MACC1, part of the HGF-MET pathway, drives proliferation and regulation of MET expression in vitro. In vivo, MACC1 is associated with tumor progression and studies suggest greater MACC1 expression is associated with resistance to platinum-based chemotherapy. We hypothesized that MACC1 may be a prognostic biomarker in colorectal cancer (CRC). Methods: MACC1 expression was evaluated by immunohistochemistry on tumor microarrays (N = 428). Patients were stage I-III CRC who received an oxaliplatin-based regimen (either with 5-FU (FOLFOX) or capecitabine (XELOX)) within the HeCOG 6C/08 observational study. MACC1 expression was assessed by a blinded GI pathologist using a scale ranging from 0 (no staining) to 3+ (strong expression). Each patient had at least 3 samples and the strongest result was used for the final score. MACC1 positivity was defined as ≥2+ expression and 0-1+ as MACC1-. Cox regression models were used to estimate hazard ratios (HR) for the association of MACC1 expression with patient characteristics, disease-free (DFS), and overall survival (OS). Results: 400/428 CRC tumors were evaluable: 322 (80.5%) were MACC1+ and 78 (19.5%) MACC1-. Mucinous features were less likely in MACC1+ patients (24% vs. 38%, p = 0.02). Other unfavorable features including grade, lymphovascular invasion, perineural invasion, and tumor mutational burden were not significantly different. There was no difference for stage, microsatellite instability, BRAF, KRAS, or NRASstatus between MACC1+/- cancers. There was a trend towards worse survival in MACC1+ patients regardless of treatment (DFS HR 1.55 [95% CI: 0.87, 2.76], OS HR 1.59 [95% CI 0.74, 3.4]). This difference was not statistically significant for OS (p = 0.26) or DFS (p = 0.08) even when stratified by clinicopathologic variables. Conclusions: Patients with MACC1+ CRC tumors who received adjuvant oxaliplatin-based therapy were less likely to have mucinous histology. They had a trend toward independently worse survival that was not significant when accounting for stage and clinicopathologic variables. Studies focused on the predictive role of MACC1 and oxaliplatin in stage III CRC are in progress.
Survival after secondary liver resection in metastatic colorectal cancer: A comparative analysis of the LICC trial with historical controls (CELIM, FIRE-3).
Authors: Moehler Markus Hermann , Folprecht Gunnar , Heinemann Volker , Holch Julian , Maderer Annett , Kasper Stefan , Hegewisch-Becker Susanna , Schroeder Jan , Overkamp Friedrich , Kullmann Frank , Bechstein Wolf Otto , Vöhringer Matthias , Oellinger Robert , Lordick Florian , Geissler Michael , Schulz-Abelius Armin , Linz Bernhard , Bernhard Helga , Schmidtmann Irene , Schimanski Carl Christoph
Published: January 2019

571

Background: Metastatic colorectal cancer (mCRC) patients (pts) with liver-limited disease (LLD) have a chance of long-term overall survival (OS) and potential cure after complete hepatic metastasectomy. The appropriate postoperative treatment strategy is still controversial. L-BLP25 as antigen-specific cancer vaccine targeting mucin 1 (MUC1) was recently evaluated as adjuvant therapy in mCRC pts after R0/R1 LLD resection (LICC trial, NCT01462513). Here we compared the LICC surveillance program and efficacy results for secondarily resected LLD pts versus historical controls, i.e. the CELIM trial (Folprecht et al, Ann Oncol 2014) of potentially resectable LLD mCRC pts and a FIRE-3-LLD subgroup (Holch et al, Int J Cancer 2018). Methods: LICC, CELIM and FIRE-3-LLD subgroup pts with stage IV mCRC limited to liver metastases who underwent hepatic resection (R0 or R1) were compared regarding pts characteristics, surveillance and efficacy outcome. LICC pts received adjuvant L-BLP25 or placebo after secondary LLD resection as 8 weekly doses, followed by 6 week maintenance intervals and tight surveillance until recurrence or a maximum of 2 years. Results: In LICC, 41/121 pts (33.9%) were secondarily resected, and R0 resection was achieved in 31 pts (75.6%). In CELIM, 36/106 pts (34%) with primary unresectable LLD were secondarily R0 resected. In FIRE-3-LLD, secondary resection was feasible for 29/133 pts (21.8%). After R0 resection, median recurrence free survival (mRFS) was 8.9 months in LICC, 9.9 months in CELIM and 11.5/12.4 months in FIRE-3-LLD in either treatment arm. In the LICC trial, median overall survival (mOS) in secondarily resected pts was 65.1 months, with 38.3 months for the R1 and is not yet reached for the R0 subgroup. In CELIM, mOS was 53.9 months for R0 resected pts. In FIRE-3-LLD, after secondary resection mOS was 56.2 months. Median age was about 5 years less in LICC. Further details will be presented. Conclusions: Secondary resected pts of LICC, CELIM and FIRE-3 showed impressive median OS with better OS for LICC and a younger patient cohort. The established tight LICC surveillance program after surgery might have had a positive impact on survival. Clinical trial information: LICC: NCT01462513; FIRE-3: NCT00433927; CELIM: NCT00153998.
Integrated profiling the patterns of pathologic response to neoadjuvant chemoradiation and the genomic-based radiation sensitivity in rectal cancer.
Authors: Yuan Zhigang , Ahmed Kamran A. , Naqvi Syeda Mahrukh Hussnain , Schell Michael J. , Felder Seth , Sanchez Julian , Dessureault Sophie , Imanirad Iman , Kim Richard D. , Torres-Roca Javier , Hoffe Sarah E. , Frakes Jessica
Published: January 2019

573

Background: Given the lack of biomarkers to predict a pathologic complete response (pCR) after neoadjuvant chemoradiation (NACRT) for rectal cancer, selection for non-operative management (NOM) mandates complete clinical response. We have previously developed/validated a model to assess genomic-based tumor radiosensitivity: the radiosensitivity index (RSI), which formulates a clinically actionable model to calculate genomic-adjusted radiation dose (GARD). We determined the profiles of RSI and GARD for rectal cancer and correlated these findings with the pathologic response patterns. Methods: One hundred seventeen rectal cancer patients treated from 2009 to 2018 with NACRT were assessed for the tumor regression grade (TRG) (0 = pCR; 1 = moderate response; 2 = partial response; 3 = poor response). RSI was analyzed in an independent tissue cohort of 113 resected rectal cancer samples. GARD was derived as described before, which shows a high GARD value indicated a superior therapeutic effect of radiation. Results: Median follow-up from completion of NACRT was 26 months. The primary tumor stages were 7% T2, 84% T3, and 9% T4. The majority of patients (82%) received concurrent 5-FU or Capecitabine and (83%) received RT dose of 50.4 Gy (range 45-56 Gy). Median time from end of NACRT to surgery was 61 days (range 36-105 days). The patterns of pathological response were TRG 0 (n = 24; 21%), 1 (n = 62; 53%), 2 (n = 25; 21%), and 3 (n = 6; 5%), suggesting heterogeneous sensitivity to treatment with similar tumor stage and treatment regimens. The median RSI for the tissue cohort was 0.46 (range 0.19-0.81) with 37% of the samples considered radiosensitive based on prior data. GARD values ranged from 5.17 to 41.79 (median 19.24), suggesting heterogeneous RT therapeutic effects. Conclusions: The findings from the clinical cohort were consistent with the tissue cohort showing significant heterogeneity in the individual tumor radiosensitivity and GARD-based RT therapeutic effects. With the development of GARD-based prospective trials, we anticipate more biology-based customized RT dosing which could optimize patient selection for NOM and individualize the most appropriate dose for each patient.
Oncogenic alterations detected by droplet digital PCR in patients with metastatic colorectal cancer resistant to cetuximab.
Authors: Liu Rujiao , Chen Zhi-Yu , Guo Weijian , Zhu Xiaodong , Huang Mingzhu , Zhang Wen , Zhao Xiaoying , Qiu Lixin , Zhang Xiaowei , Zhang Zhe , Wang Chenchen , Li Wenhua
Published: January 2019

575

Background: Anti-EGFR therapy is the standard of care for metastatic colorectal cancer (mCRC) patients with RAS and BRAF genes wild type (wt). Secondary alterations of several genes have been identified as possibly resistant mechanisms to EGFR blockade, these including mutations of KRAS, NRAS, BRAF, MEK and EGFR ectodomain, as well as amplifications of HER2 and c-MET. In this study, we investigated alterations of these targeted genes for mCRC patients with acquired resistance to cetuximab treatment by using non-invasive droplet digital PCR (ddPCR) method within circulating DNA. Methods: We enrolled 38 RAS and BRAF wt patients, who progressed after failure of cetuximab contained regimens between Jul 2015 and Jan 2018. Plasma samples from all 38 patients were collected and detected for seven candidates (mutation of KRAS, NRAS, EGFR, BRAF, MEK, amplification of HER2, c-MET) by using ddPCR at the time of baseline, each evaluation by interval of 2 months and documented progression. All clinical parameters were collected simultaneously. Results: A total of 23 secondary alterations were found in 17 (17/38,44.7%) cetuximab resistant patients. The targeted gene alterations were detected as follows: 9 (9/23,39%) RAS mutations, 5 (22%) HER2 amplifications, 5 (22%) EGFR mutations, 2 (9%) c-MET amplifications, 1 (4%) BRAF and 1 MEK mutation. Among 17 patients, 6 patients had multiple alterations, including 2 patients with KRAS+EGFR mutations, 2 patients with HER2+c-MET co-amplifications and 2 patients with KRAS gene exon 2 and 3 multiple mutations. Primary sites were 15 left sides and 2 right sides, descending colon (12 cases) was the most common origins. Eleven patients were synchronous disease. Twelve patients received cetuximab as first line therapy, whereas 5 patients in the ≥ 2nd line setting. All of these 17 patients, plasma levels of oncogenic alterations detected by ddPCR were showed dynamic changing and good agreement with tumor responding status. Conclusions: Oncogenic alterations detected by ddPCR were found in almost half mCRC patients resistant to cetuximab. Dynamic changes of specific alteration may facilitate making decisions for selection of anti-EGFR mAb during the treatment course.
Comparison of HER2 expression by immunohistochemistry and HER2 copy number by digital PCR in tumor tissue during treatment with trastuzumab in the prospective cohort of metastatic HER2-positive gastric cancer patients.
Authors: Takahashi Naoki , Iwasa Satoru , Matsushima Tomohiro , Miyazawa Shoichi , Kumekawa Yosuke , Shimizu Satoshi , Yoshii Takako , Asayama Masako , Hara Hiroki
Published: January 2019

58

Background: Trastuzumab (Tmab) is an active molecular-targeted drug for HER2-positive gastric cancer (GC) patients. HER2 expression is known to change during the treatment of Tmab and HER2 amplification in blood is widely investigated as a new biomarker of the treatment candidate or the monitoring of HER2-target therapy. We evaluated the change of the HER2 expression by immunohistochemistory (IHC) and HER2 copy number by degital PCR during the treatment with Tmab in metastatic HER2-positive GC patients. Methods: Metastatic HER2-positive GC patients treated with Tmab were registered prospectively, and tissues were obtained by biopsy from primary lesions at the following points: (1) pre-treatment, (2) post-treatment, and (3) disease progression during chemotherapy with Tmab. Formalin-fixed paraffin-embedded tissue slides were prepared, and the expression of HER2 expression were scored by IHC and HER2 copy number were evaluated by digital-PCR. Results: Among 20 enrolled patients, HER2 expression was evaluated by IHC in all patients. HER2 copy number was evaluated by digital PCR in 15 patients. A patient was excluded because HER2 expression were not detected by re-evaluation. The median of HER2 copy number of 33 sampling points during the treatment was 6.37 (range: 2.12 - 85.8). The median of HER2 copy number of IHC 3+, IHC 2+, IHC 0-1 were 22.4 (3.37 – 85.8), 2.88 (2.65 – 3.6), 2.37 (2.12 – 3.85), respectively. High level of HER2 copy number was detected in tumor tissues of HER2 IHC 3+ compared with that of IHC≦2+. HER2 expression by IHC was disappeared after treatment of Tmab in 42% of HER2-positive patients. Among these patients, HER2 copy number at pre-treatment were relatively low (2.63 - 3.6). Conclusions: High copy number of HER2 was detected in tumor tissues with HER2 IHC3+ in HER2-positive GC patients during the treatment of Tmab. In addition, low copy number of HER2 in tumor tissues at pre-treatment may be associated with the loss of HER2 expression after treatment of Tmab. Further research by large number of patients to confirm our results is required.
KRAS mutation as a predictor for cause-specific survival in early- versus late-onset colorectal cancer: A United States population-based study.
Authors: Lin Albert Y. , Kahl Amanda R , Pan Jennifer Y. , Lo Joshua , Tung Winifred , Fisher George A. , Charlton Mary E.
Published: January 2019

580

Background: While the overall incidence rates for colorectal cancer (CRC) —the third leading cancer diagnosis in the U.S.—have been decreasing over the last several decades, incidence rates for early-onset (EO, age 20-49 years) CRC have shown an upward trend. Multiple studies have documented mutations in KRAS proto-oncogene (KRAS) as a poor prognostic factor in sporadic CRC, but its impact on EO versus late-onset (LO, age > 49 years) CRC is unclear. Methods: Surveillance, Epidemiology, and End Results (SEER) Program data were queried to identify pathologically-confirmed CRC cases tested for KRAS and diagnosed between 2010 and 2015. Demographic, histologic, and KRAS data were compared between EO and LO using Chi-square tests. Kaplan-Meier and Cox proportional hazards models were used to estimate cause-specific survival (CSS) and examine factors associated with CSS. Results: Of 202,173 CRC cases, 3,842 EO and 17,819 LO CRC cases had KRAS testing with a KRAS mutation frequency of 40% and 41%, respectively. Compared with LO tumors harboring mutated KRAS, EO tumors with KRAS mutations were more frequently found in females (52% vs. 45%, P < 0.001), left-sided (LS) or rectal cancers (62% vs. 48%, P < 0.001), stage III/IV (89% vs. 81%, P < 0.001), and grade III/IV (21% vs. 18%, P = 0.038). Compared to CSS in EO with KRAS mutation, LO with KRAS mutation was associated with worse prognosis—with an overall hazard ratio (HR) of 1.21 (95% CI, 1.15-1.27, P < 0.0001). Results [HR (95% CI)] from Cox analyses on the effects of KRAS mutation on CSS, stratified by sidedness, are shown below. Conclusions: Despite EO CRC carrying worse prognostic factors than LO CRC, it confers better CSS than LO CRC. EO CRC is distinct from LO CRC in clinical and pathological features, in addition to its response to mutant KRAS. Mutated KRAS is an independent prognostic factor in LS colon and rectal cancers among the LO, but not in the EO population. [Table: see text]
Comparison of phosphoproteomic profiles in left- and right-sided colorectal cancers.
Authors: Buffart Tineke , Beekhof Robin , van den Oord Rosanne , de Haas Richard R. , Pham Thang V. , Dekker Henk , van Grieken Nicole C.T. , Piersma Sander R. , van den Brule Adriaan , Nooijen Peet , Pruijt Hans , Jiménez Connie R. , Verheul Henk M.W.
Published: January 2019

582

Background: Left- and right-sided colorectal cancers (CRCs) are different in terms of prognosis, treatment response and underlying molecular mechanisms. The aim of this study was to unravel the phosphoproteomic profiles of left- and right-sided primary CRCs and to identify potential drug targets for both primary tumor sites. Methods: In total phosphoproteomic profiles of 69 fresh-frozen biopsies, including 34 left-sided and 35 right-sided primary CRCs, were obtained by LC-MS/MS after cell lysis, digestion and phosphopeptide enrichment using anti-phosphotyrosine antibodies. MS/MS spectra were searched against a UniProt human reference proteome FASTA file using MaxQuant software. Fold changes between normalized intensities were calculated. Group comparison was performed using the R package Limma. P values below 0.01 and fold changes > two were considered significant and biologically relevant. Results: In total 2,840 phosphopeptides were detected in at least 5% of the samples. Of these, 36 phosphopeptides were significantly upregulated and 14 were significantly downregulated in right-sided compared to left-sided CRCs using our stringent selection criteria. Since BRAF mutations and deficient DNA mismatch repair (dMMR) were more frequently observed in right-sided CRC (p < 0.01), group comparison was repeated with MMR proficient CRCs only, resulting in 21 phosphopeptides up- and one downregulated in left- versus right-sided CRC. The identified phosphoproteins from the phosphopeptides included three FDA approved drug targets. Conclusions: Differences in phosphoproteomic profiles were detected between left- and right-sided CRCs, besides molecular differences such as BRAF mutation and MMR status. These results indicate that the molecular biology of left-and right-sided CRCs may explain their differences in clinical behavior and response to treatment.
Predicting the pathologic complete regression with hematologic markers during neoadjuvant chemoradiotherapy in the locally advanced rectal cancer.
Authors: Kim Jae-Sung , Lee Joo Ho , Song Changhoon
Published: January 2019

583

Background: The present study aimed to evaluate the hematologic markers for predicting the pathologic complete regression during and after neoadjuvant chemoradiotherapy (CRT) in patients with locally advanced rectal cancer. Methods: Total 297 patients with rectal cancer underwent neoadjuvant CRT followed by surgical resection and performed complete blood counts (CBC) serially during and after CRT. The timepoints of CBC were before CRT (pre-), three weeks after the day of starting CRT (intra-), and four weeks after CRT (post-). We calculated the platelet-to-lymphocyte ratio (PLR), neutrophil-to-lymphocyte (NLR), derived neutrophil-to-lymphocyte (dNLR) using the serial CBC test. The ratio of change in PLR (cPLR), NLR (cNLR), and dNLR (cdNLR) was calculated as the change of value/pre-value. Chi-square and T-test for univariate analysis and multivariate logistic regression were performed to identify the significant predictor for pCR. Receiver operating characteristics (ROC) analysis was used to compare the predictive values. Results: The overall rate of pCR was 15.9%. The Pre-Hb, pre-NLR, intra-PLR, intra-NLR, intra-cPLR, intra-cNLR, post-WBC, post-Hb, and post-cPLR were significantly different between patients with pCR and no pCR. In the multivariate logstic regression, pre-Hb (OR 1.456 p-value .026), intra-cPLR (OR 4.949, p-value < .001), post-WBC (OR 0.664, p-value .008), and post-PLR (OR 1.011 p-value .001) were significant predictors for pCR. In the comparison of ROCs, intra-cPLR was the most accurate predictor for pCR among the hematologic variables (AUC = 0.74, p ≤ .001). Conclusions: Change of PLR during neoadjuvant CRT is the clinically applicable and significant predictor for pCR with high negative predictive value in the patients with LRC.
The impact of sidedness of colorectal cancer in tumor immunity.
Authors: Nishi Masaaki , Shimada Mitsuo , Kashihara Hideya , Higashijima Jun , Yoshikawa Kozo , Tokunaga Takuya , Miyatani Tomohiko , Takasu Chie , Iwahashi Shoko
Published: January 2019

584

Background: Clinical and molecular characteristics are different between Right-side and left-sided colorectal cancer (CRC). The aim of this study was to clarify the significance of the correlation of the Sidedness of CRC and tumor immunity. Methods: A total of 116 patients who underwent curative colectomy for stage II/III CRC were included in this study. The expression of PD-1, PD-L1, FoxP3, TGF-b, and IDO was examined by immunohistochemistry and the relationship of sidedness to several prognostic factors was examined. Results: In clinicopathological factors, there were no significant difference between right sided and left sided CRC except for differentiation. Regarding tumor immunity, there were no significant difference in PD-1 and IDO expression. However, Fox P3 (right side 72% vs. left side 59%) and TGFβ (right side 72% vs. left side 57%) tended to be highly expressed in right side(p < 0.1). PDL1 was significantly highly expressed in right side(right side 65% vs. left side 35%, p < 0.05). In OS and DFS, the patients with right sided tumor tended to have poor prognosis compared with left side (p < 0.1). The PD-L1 positive patients of right-sided tumor had poor prognosis (p < 0.05). Conclusions: Sidedness is associated with tumor immunity in colorectal cancer.
Characterization of chemoradiation-induced changes in immune cells and targets for personalized therapy in locally advanced rectal cancer (LARC).
Authors: Fontana Elisa , Wilkins Anna , Patil Yatish , Nyamundanda Gift , Ragulan Chanthirika , Mansfield David , Kingston Jennifer , Errington-Mais Fiona , West Nicholas , Bottomley Daniel , Downs Jessica , Demaria Sandra , Harrington Kevin Joseph , Melcher Alan , Sadanandam Anguraj
Published: January 2019

589

Background: Neoadjuvant radio/chemoradiotherapy (CRT) is a treatment milestone for LARC. The importance of immune response in CRT efficacy is increasingly realised. However immune cell changes associated with poor responders and their modulation with immune-CRT combinations is unclear. Methods: Matched archival pre-CRT biopsies and post-CRT resection specimens from patients (pts) treated with neoadjuvant CRT were retrieved. Delta-TCD (tumor cell density, estimated using quantitative point counting on virtual tissue H&E) and k-means clustering method were used to classify pts into good, intermediate and poor responders. Baseline expression and CRT-induced changes in 770 immune-related genes (plus 30 DNA damage response genes) were evaluated using NanoString Technologies. Results: At least 70 pts treated with short/long course radiotherapy (SCRT/LCRT) and matched tissues available were identified. To date, 27 pts evaluable for deltaTCD and gene expression were clustered into good (n:10), intermediate (n:7) and poor (n:10) responders. The expression of 14% (91/636) of immune genes was significantly affected by CRT (Bonferroni t-test, q-value < 0.05) overall, with significant increase in innate immunity and decrease in adaptive immunity across all pts (CIBERSORT and SSGSEA analyses). Between good and poor responders there were 6% (39/636) and 2% (15/636) of genes significantly affected by CRT (Bonferroni t-test, q-value < 0.05), respectively. CRT-induced increased CD8+ T cells expression in poor responders compared to good responders was seen. Increased baseline expression of resistance genes (including PD-L1, IDO1 and IL2RA) were seen in poor versus good responders. Validation with quantitative multiplex-immunofluorescence (Vectra) and correlation with SCRT/LCRT and time to surgery are on-going. Conclusions: The expression of immune-related genes is significantly modified by CRT in LARC. With the caveat of small numbers, we identified differentially expressed immune targets at baseline which may justify immune-CRT combinations in neoadjuvant setting in selected pts to modulate the CRT effect and ultimately increase response.
Trifluridine/tipiracil (FTD/TPI) and regorafenib (REG) in patients with metastatic colorectal cancer (mCRC): A single institution retrospective study.
Authors: Patel Anuj K. , Ng Kimmie , Duh Mei Sheng , Barghout Victoria E. , Huynh Lynn , Yenikomshian Mihran Ara , Sharperson Camara , Brais Lauren K. , Fuchs Charles S.
Published: January 2019

592

Background: FTD/TPI and REG have both demonstrated prolonged survival in refractory mCRC patients (pts) when compared to placebo but limited comparative effectiveness data are available. This study aims to compare outcomes following initiation of FTD/TPI or REG for mCRC at a single academic cancer center. Methods: Retrospective chart reviews were conducted in all pts with mCRC who initiated FTD/TPI or REG between 2012-2017. Analyses of time from index therapy initiation to discontinuation for any reason (TTD), real-world response rates (rwRR) and disease control rates (rwDCR) were performed. Cox proportional hazards models adjusting for demographic and clinical characteristics were performed for overall survival (OS). Results: 126 FTD/TPI and 95 REG pts were included. Baseline characteristics were similar in both groups, though more pts treated with FTD/TPI had right-sided primary tumors compared to REG (30.4% vs. 25.5%, p = 0.43). Treatment patterns pre- and post-index therapy were comparable in both groups. Median observation duration for FTD/TPI and REG was 7.1 and 6.3 months, respectively. Mean TTD was 88.4 days for FTD/TPI pts and 84.2 days for REG pts (p = 0.42). Fewer pts treated with FTD/TPI discontinued due to toxicities than pts treated with REG (8.2% vs. 24.2%, p = 0.001). A higher proportion of FTD/TPI pts had no dose modifications vs. REG pts (84.0% vs. 64.1%, p < 0.001). OS was similar between the two groups (adjusted hazard ratio [HR] FTD/TPI vs. REG: 0.79, p = 0.13). FTD/TPI pts had higher rwRR (52.5% vs. 34.2%, p = 0.01) and rwDCR (64.2% vs. 46.1%, p = 0.01) than REG pts. In the subgroup of pts ≥ 65 years, mean TTD was higher in FTD/TPI pts (105.9 vs. 77.6 days, p = 0.004). Pts ≥ 65 years receiving FTD/TPI had better OS than REG pts (HR: 0.51, p = 0.03). Conclusions: In this single institution study, TTD and OS were similar between pts treated with FTD/TPI and REG. Fewer pts treated with FTD/TPI than REG discontinued due to toxicities or required dose modification. Reported responses rates were higher in FTD/TPI pts. Older pts (≥ 65 years) on FTD/TPI remained on treatment longer and had better OS than REG pts.
Biomarkers of immunotherapy response in rectal adenocarcinoma treated with neoadjuvant chemoradiotherapy.
Authors: Kaur Gurveen , Tayshetye Pritam , Jani Prashant Mukesh , Omstead Ashten N , Renz Paul , Brem Candice , Hasan Shaakir , Sandhu Ariel , Joseph Paul , Babar Laila , Zheng Ping , Zaidi Ali Hussainy , McCormick James , Kirichenko Alexander V. , Miller Stacey , Raj Moses S. , Silverman Jan F , Finley Gene Grant
Published: January 2019

593

Background: Immunotherapy (IO) in combination with chemoradiotherapy (CRT) in the neoadjuvant treatment for locally advanced rectal adenocarcinoma (RAC) is an area of active clinical research. There are no well-defined biomarkers in RAC predicting response to neoadjuvant therapy. Increase in tumor PD-L1 expression and tumor infiltrating lymphocytes (TIL) has been observed after neoadjuvant CRT which potentially enhances response to IO. We report herein expression of PD-L1 and CD8+ TIL and other biomarkers of immune activation including CXCL9, TIM3 (HAVCR2), IDO1, IFNG, IL17RE, LAG3 and OX40 (TNFRSF4) pre and post neoadjuvant CRT in RAC. Methods: We retrospectively evaluated 38 RAC patients from 2007-2016 treated with neoadjuvant CRT using 5FU based therapy. Pre and post CRT tissue samples were stained with VENTANA PD-L1 (SP263) rabbit monoclonal antibody to quantify PD-L1 expression. CD8+ TIL were recorded over one high power field (hpf) (40x objective) in the area of densest infiltrate. Additional biomarkers CXCL9, TIM3 (HAVCR2), IDO1, IFNG, IL17RE, LAG3 and OX40 (TNFRSF4) were assayed with RT-PCR. Independent sample and paired sample t-tests were used for statistical analysis of difference in biomarker expression. Relevant clinical endpoints including local relapse, distant metastases and survival were collected. Results: Median age was 60 years (range 32–87). Median follow up was 16.7 months (range 2.6-120.1). Median duration from completion of CRT to resection was 73 days (range 44–315). PD-L1 expression increased from 10% to 23% in pre-CRT versus post-CRT patients. CD8+ TIL increased in 30/39 (83%) patients with an average increase from 66.48 to 129.20 CD8+ TIL/hpf in the pre-CRT versus post-CRT setting. Using RT-PCR, a statistically significant increase in the expression of CXCL9, IFNG and OX40 (TNFRSF4) was found pre-CRT versus post-CRT using paired samples t-test. Conclusions: Neoadjuvant CRT for RAC increased PD-L1 expression and CD8+ TIL along with an increased expression of CXCL9, IFNG and OX40 (TNFRSF4). These data suggest a novel role for IO in neoadjuvant treatment of rectal cancer. Clinical outcome data on these patients will be presented.
Guanylate cyclase C (GUCY2C) as a preventative and therapeutic target in colorectal cancers (CRCs) arising through divergent genomic pathways.
Authors: Bashir Babar , Merlino Dante , Rappaport Jeffrey , Gnass Esteban D , Palazzo Juan , Fing Yeng , Fearon Eric R , Snook Adam , Waldman Scott A
Published: January 2019

595

Background: CRCs arise through distinct mutations, including in APC pathway leading to tubular adenomas (TAs); in BRAF, with epigenetic silencing of CDX2, leading to serrated adenomas (SAs); and in the DNA mismatch repair machinery driving microsatellite instability (MSI). The APC pathway involves loss of the hormone guanylin, silencing the tumor suppressing receptor GUCY2C. Indeed, oral hormone replacement is an emerging strategy to reactivate GUCY2C and prevent CRC. Moreover, retained expression by tumors arising from TAs has established GUCY2C as a therapeutic target to prevent and treat metastatic CRC. Here, we defined the potential role of the guanylin-GUCY2C axis, and its suitability as a target, in tumors arising through the SA and MSI pathways. Methods: We compared guanylin-GUCY2C protein and mRNA expression between human TAs (n = 18), SAs (n = 15), MSI tumors (n = 7) and their matched normal adjacent tissue. Genetic mouse models of serrated and MSI tumors were used to confirm findings and elucidate mechanisms. Results: Guanylin hormone was eliminated in TAs, SAs and MSI tumors compared to their normal adjacent tissues. In contrast to the hormone, the tumor suppressing receptor GUCY2C was retained in TAs and MSI tumors. Surprisingly, GUCY2C expression was nearly eliminated in SAs reflecting loss of the transcription factor CDX2. Changes in the guanylin-GUCY2C axis in human SAs and MSI tumors were precisely recapitulated in genetic mouse models. Conclusions: Guanylin is universally lost at the earliest stages of transformation in tumors arising through divergent genomic mechanisms suggesting its utility as a biomarker of CRC initiation. These data reveal the possibility of guanylin loss silencing GUCY2C in the pathophysiology of, and oral hormone replacement to restore GUCY2C signaling to prevent, MSI tumors. Also, they highlight the potential for targeting GUCY2C to prevent and treat metastases arising from TAs and MSI tumors. In contrast, loss of GUCY2C excludes patients with SAs as candidates for GUCY2C-based prevention and therapy.
CMS-PDX: A 20-gene genomic panel to predict consensus molecular subtypes in patient-derived xenografts (PDX) of colorectal cancer.
Authors: Buechler Steven Allen , Gokmen-Polar Yesim , Badve Sunil S.
Published: January 2019

598

Background: The consensus molecular subtypes (CMS1-4) partition colorectal cancer (CRC) into subgroups with varying prognoses and treatment responses. We previously reported the ColotypeR-CMS genomic scores (4 scores defined with 5 genes each) that accurately define the CMS subtypes of primary CRC tumors. There is also a critical need to develop an epithelial cell based algorithm for CMS subtyping of PDX models. Methods: To define scores predicting CMS subtypes for PDX models, genes that both predict CMS subtypes in primary CRC tissue and that have linearly correlated expression in primary tumor and tissue-matched PDX models, were identified in GSE35144 (N = 64, Affymetrix microarray). Using the identified genes, a 20-gene CMS-PDX score was developed using multistate gene methodology. ROC curve (AUC) analysis was used to measure the ability of CMS-PDX scores to predict subtypes obtained with CMScaller (473 genes), a preclinical CMS classifier. The ability of CMS subtypes to determine cetuximab response in PDX cohorts was analyzed in GSE78806 (N = 121, Affymetrix microarray) and GSE76402 (N = 529, Illumina beadarray). Results: In GSE78806 (N = 121), CMS1-4 subtypes obtained with CMScaller were predicted by CMS-PDX scores with AUC 0.88, 0.94, 0.81, 0.86, respectively; in GSE78806 CMScaller failed to classify 32% of samples. In CRC-derived PDX models, higher values of the CMS-PDX CMS2 score were predictive of reduced tumor volume following cetuximab treatment (p = 1.7 x 10-5in GSE78806, p < 2.2 x 10-16in GSE76402, by linear regression.) In contrast, higher values of the CMS1 score were predictive of increased tumor volume (p = 3.8 x 10-5in GSE78806, p = 2.9 x 10-10in GSE76402.) Change in tumor volume was independent of the CMS-PDX CMS4 score in both PDX cohorts. Conclusions: We showed that the 20-genes CMS-PDX scores are predictive of CMS subtypes obtained with CMScaller. Moreover, CMS2, by CMS-PDX scores, was highly predictive of sensitivity to cetuximab treatment in CRC PDX models.
ColotypeR gene signature predicts response to cetuximab in colorectal cancer metastases.
Authors: Buechler Steven Allen , Gokmen-Polar Yesim , Badve Sunil S.
Published: January 2019

599

Background: The consensus molecular subtypes (CMS1-4) partition primary colorectal cancer (CRC) into subgroups with distinct molecular characteristics. We previously reported a 20-genes ColotypeR-CMS signature that accurately defines CMS subtypes for primary CRC tumor samples. The utility of CMS subtyping in defining response to treatment of CRC metastases remains to be established. Here, we report the ability of ColotypeR scores to predict differential response to cetuximab among CMS subtypes in CRC metastases. Methods: The role of ColotypeR-CMS signature scores was assessed in CRC metastasis samples (GSE5851, N = 68, Affymetrix microarray) in predicting response to cetuximab. Progression-free survival (PFS) was the primary endpoint. The predictive significance of ColotypeR-CMS scores relative to KRAS mutation status was also studied using multivariate Cox proportional hazards models. Results: ColotypeR-CMS scores were computed in GSE5851 using the algorithm developed in primary tumor samples. Higher values of ColotypeR-CMS CMS2 score were significantly predictive of longer PFS (p = 5 x 10-5for the score test in Cox proportional hazards model; hazard ratio 0.20 (95%CI 0.09-0.44) in CRC metastases samples (GSE5851, N = 68) treated with cetuximab. PFS was independent of CMS1,3, 4 scores. KRAS wild type tumors had significantly longer PFS (p = 0.01; hazard ratio 0.49 (95%CI 0.28-0.86). In multivariate survival analysis, ColotypeR-CMS CMS2 score added to the significance of KRAS status (p = 0.012) and ColotypeR-CMS CMS2 score was predictive of longer PFS in KRAS wild type tumors (p = 0.009; hazard ratio 0.20 (95%CI 0.06-0.69)). Conclusions: We showed that in CRC metastasis samples, the ColotypeR CMS2 score was highly predictive of sensitivity to cetuximab treatment, while no increase in PFS was observed for higher values of CMS1, 3, 4 scores.
Quantifying the evolution of tumor architecture using serial circulating tumor DNA.
Authors: Henry Jason , Loree Jonathan M. , Strickler John H. , Raghav Kanwal Pratap Singh , Morris Van K. , Raymond Victoria M. , Lanman Richard B. , Yaeger Rona , Corcoran Ryan Bruce , Overman Michael J. , Kopetz Scott
Published: January 2019

600

Background: There is limited data regarding changes in the genomic landscape in individual patients over time as serial tissue biopsy has risk and is of uncertain clinical benefit. The advent of circulating tumor DNA (ctDNA) allows for safe and repeated molecular sampling with the potential to investigate evolution of tumor architecture over the disease course. Methods: From 5/15 to 12/17, 116 patients with metastatic CRC had between three to 12 blood specimens taken over the treatment course. Plasma was tested using targeted NGS assay (Guardant360, Guardant Health, 68 gene). To account for variations in the amount of ctDNA in serial samples, a window of evaluable allele frequency was established for each patient as the fold change between the max allele frequency (mAF) and limit of detection for serial samples with the lowest mAF. Mutations not falling within this window were excluded from analysis. Substantial treatment induced selective pressure (SP) was defined as a decrease in the mutant mAF of > 50% in patients with at least an initial mAF of 1%. Results: 116 patients with a total of 317 serial blood samples were evaluable after accounting for ctDNA variations over time. Specimens were collected a median of 12 months apart, with a median of three specimens per patient. Thirteen patients (11%) did not have any changes in mutations on serial sampling, however the remainder of patients gained an average of 1.1 mutations per time point (mut/tp), and lost 1.0 mut/tp. 31% of patients demonstrated evidence of substantial treatment-induced SP. These patients were more likely to demonstrate a change in clonal architecture of the tumor (46% greater rate than those without SP, P = 0.04), predominantly through gain of new clones. In contrast, clonal hematopoiesis alterations that may be induced by chemotherapy, such as JAK2V617F, were neither gained or lost. Conclusions: After correction for variations over time in the total amount of ctDNA in circulation, we identify numerous changes in tumor architecture with serial sampling. For the first time in colorectal cancer we demonstrate that when treatment-induced SP is applied the rate of tumor evolution is increased, demonstrating potential value of monitoring changes in tumor architecture over the disease course.
Alternative chemoradiotherapy to treat locally advanced (LA) anal carcinoma (AC) in patients (pts) with mutations in thymidylate synthase (TYMS) and dihydropyrimidine dehydrogenase (DPYD) genes: A case series.
Authors: Saif Wasif M. , Hamal Ruchi , Siddiqui Nauman Saleem , Maloney Antonia , Chen Lilian , Huber Kathryn
Published: January 2019

605

Background: 5-FU and mitomycin-C (MMC) with radiotherapy (RT) remain an established treatment for pts with LA (T2-4, N0-1, M0 or T1-4, N2-3, M0) AC. Genetic mutations in 2 major metabolizing enzymes for 5-FU; DPYD and TYMS have been associated with clinical response and toxicity. However their place in treatment of AC remains undetermined. Methods: We retrospectively reviewed 21 pts with LA AC treated between 2012 - 2018. All pts were treated with 5-FU 1,000mg/m2/day continuous IV infusion 1–4 and 29–32, MMC 10mg/m2 IV bolus Days 1 and 29 plus RT. Acute toxicity was recorded and discussed during weekly multidisciplinary meetings. The worst grade was scored from start of treatment until 30 days after the last fraction of radiotherapy according to the NCI-CTCAE, v4.03. Tumor response was evaluated by DRE and palpation of inguinal nodes during treatment, at the end of treatment, and radiological imaging 4–6 weeks after completion of treatment. Pts who developed ≥3 toxicities were tested for DPYD and TYMS genes (2 major polymorphisms has been associated with altered TYMS: polymorphic 28bp tandem repeat polymorphism in 5’-untranslated region (5’UTR) into TYMS sequence enhancer region (TSER) and TYMS 1494del, is a 6-base pair (bp) deletion polymorphism in 3’-UTR. Results: 6/21 ptsdeveloped severe toxicities (Caucasians; 5 females, 1 male; age range: 42 -68 yrs) consisting of grade ≥3 pancytopenia, neutropenia, thrombocytopenia, mucositis, nausea, rash and nephritis. The most common genetic mutations found in these pts included TYMS 2RG/3RC (2), 3RG/3RC (1), 2R/2R (2), TYMS 3 ' UTR del/Ins (2) and DPYD c.2864A>T heterozygous (1). Treatment was changed in 2 pts to MMC 10 mg/m2 Day 1 and 29 with cisplatin 25 mg/m2/week plus RT. These 2 pts reached pCR at 70 days and other 4 pts at 140 days. Conclusions: Molecular testing for DPYD and TYMS genes can allow us to identify pts who are most likely to respond or face severe toxicity to 5-FU. Combining radiation with MMC and cisplatin in pts with LA AC is feasible and EORTC is currently comparing this combination with MMC/5-FU in a large phase III trial.
Racial disparity in gastrointestinal cancer: Insight from national cancer database.
Authors: Singh Maharaj , Datta Samit Kumar , Papenfuss Wesley Allan , Belini Geoffrey , Chevinsky Aaron , Weese James L.
Published: January 2019

607

Background: The number of cases of cancers originating from the gastrointestinal (GI) tract and from other associated GI organs has increased 28% between the years 2004-2014. The incidence and overall survival for GI tract related cancers shows systematic racial disparity. Our goal was evaluate racial disparity for overall survival and mortality among patients with GI tract cancers. Methods: We used the national cancer database to evaluate data from 12 types of GI tract cancers (esophagus, stomach, gallbladder, intrahepatic bile duct, extrahepatic bile duct, liver, pancreas, small intestine, colon, rectosigmoid, rectum, and anal) between the years 2004-2014. The racial categories included non-Hispanic white (NHW), non-Hispanic black (NHB), Hispanic, and Other (All other races were combined into an ‘Other’ category). We used Kaplan-Meier estimator with log-rank test for comparing the survival probability among the four race categories. We also used Cox regression to find out the hazard ratio for mortality adjusting for the age, sex, and Charlson index. Results: The study population included a total of 2,044,565 patients diagnosed with one of the GI tract cancers. Of the total 55% were male, 72% NHW 12% NHB, 0.4% Hispanic, and the rest were classified as ‘other’ race (16%) which includes majority of white or black Hispanic and Asian (82%), The mean age at diagnosis of the patients was 66.8 ± 11.3 years. Overall survival was better for the Hispanic group, followed by the ‘Other’ group, NHW and NHB (P < 0.001). Adjusted for age, sex, and for Charlson index, the hazards ratio was 0.93 (95% CI, 0.90-096, p < 0.001) for Hispanic vs other, 1.15 (95% CI, 1.14-1.16, p < 0.001) for NHB vs other, 0.98 (95% CI, 0.97-0.98, p < 0.001) for NHW vs others. Mortality rate among Hispanic, NHW, NHB, and other was 46.4%, 59.4%, 59.6%, 56.7%. Conclusions: With a very large study population the survival for Hispanic patient population as well as the ‘Other’ (majority of patients were Asian) category had higher overall survival probability and low rate mortality compared to other race categories. Possible hypotheses include dietary preferences, underlying genetic profile and environmental factors. Further studies are needed to confirm the hypotheses.
CMS subtypes characterized by high TMB shows immunosuppressive microenvironment that implies resistance to immunotherapy.
Authors: Szeto Christopher , Garner Chad , Kazmierczak Kevin , Vaske Charles Joseph , Benz Stephen Charles , Reddy Sandeep K.
Published: January 2019

610

Background: Tumor mutational burden (TMB) is emerging as an important biomarker for immune checkpoint therapy (ICT) response. Yet even in the context of high TMB, ICT are likely ineffective in an immuno-suppressed microenvironment. Here we demonstrate that a well-characterized subtype of CRC, CMS2, associated with Wnt pathway activation, is immunosuppressive despite high TMB. Methods: Tumor/normal-paired DNAseq (WGS or WES) and deep RNAseq (∼200x106reads per tumor) was performed on 464 GI tumors from a commercial database. Samples were classified as high TMB if they had > 200 non-synonymous exonic mutations as previously established (Rizvi et al, 2015). Each sample was assigned to one of the colorectal Consensus Molecular subtypes (CMS) based on RNA classification. A curated panel of 109 genes that discriminate between 22 immune subsets was identified. For each of these immune signatures, a database containing 1880 unselected tumors was used to define a distribution of expression. The study samples were then scored for their deviances within such distributions. Significant enrichment was analyzed between immune subsets, CMS types, TMB status, and somatic mutational status. Results: Compared to other subtypes, CMS1 & CMS2 were significantly high-TMB (adj. p < 3.8E-4 & p < 4.7E-3 respectively). Perplexingly, CMS2 had significantly lower expression of 11 well-established checkpoint and TME markers including LAG3 and PDL1 (adj. p 1.5E-2 & 2.9E-9 respectively), while CMS1 (MSI-enriched) expresses selected TME markers more than other subtypes (PDL1 adj. p < 4.0E-6 & LAG3 adj. p < 1.0E-6). As expected, CMS2 tumors were significantly enriched for likely pathogenic variants in the Wnt-associated gene APC (adj. p < 1.3E-8). Immune-deconvolution indicated substantial exclusion of Tem cells from CMS2 tumors, in line with Wnt/b-catenin blockade of TcmàTem maturation for immunoreactivity. Conclusions: The most common subtype of CRC, CMS2 (~37%), is highly immunosuppressive despite high TMB. ICT is only effective in an immunologically active microenvironment. TMB alone as a biomarker likely is insufficient to indicate the effectiveness of immunotherapy.