CRC Tumors Research Articles

Circ_0044556 Promotes the Progression of Colorectal Cancer via the miR-665-Dependent Expression Regulation of Diaphanous Homolog 1.

Cancer progression can be regulated by noncoding circular RNAs. A recent study has indicated that circ_0044556 facilitated the progression of colorectal cancer. This research was performed to explore the regulatory mechanism of circ_0044556 in CRC. Circ_0044556, miR-665 and Diaphanous Homolog 1 levels were detected by the quantitative real-time polymerase chain reaction. Cell proliferation analysis was performed by cell counting kit-8 assay and Edu assay. Cell cycle progression was assessed using flow cytometry. The protein examination was conducted using western blot. Transwell assay was used to analyze cell migration and invasion. Dual-luciferase reporter assay was performed to validate the interaction between targets. In vivo research was implemented by xenograft tumor assay. Circ_0044556 was upregulated in colorectal cancer samples and cells. Silencing circ_0044556 inhibited cell proliferation, cell cycle progression, migration, invasion, and epithelial-mesenchymal transition in CRC cells. Circ_0044556 could directly target miR-665 and the function of circ_0044556 was associated with the regulation of miR-665. In addition, Diaphanous Homolog 1 was a target gene for miR-665 and the anti-tumor role of miR-665 in colorectal cancer was dependent on the downregulation of Diaphanous Homolog 1. Diaphanous Homolog 1 level was regulated by circ_0044556 via sponging miR-665 in CRC cells. In vivo assay suggested that circ_0044556 promoted CRC tumor growth by regulating the miR-665 and Diaphanous Homolog 1 levels. Our findings manifested that circ_0044556 functioned as an oncogenic circRNA in colorectal cancer by mediating the miR-665/Diaphanous Homolog 1 axis, elucidating the molecular mechanism of circ_0044556 in CRC progression.

SLC34A2 promotes cancer proliferation and cell cycle progression by targeting TMPRSS3 in colorectal cancer

Solute carrier family 34 member 2 (SLC34A2), a family member of sodium-driven phosphate cotransporters, has been reported to facilitate cell proliferation and tumor growth. However, the functional mechanism by which SLC34A2 promotes cell growth and cell cycle progression remains poorly understood. Here, we reported that SLC34A2 was overexpressed in CRC by analysis of TCGA and GEO datasets. A total of 45 differentially expressed genes (DEGs) were identified from comparing SLC34A2-high or –low groups and functional enrichment analysis of these DEGs demonstrated that cell cycle pathway was enriched. Interestingly, we found a positive correlation between TMPRSS3 (transmembrane serine protease 3) and SLC34A2, which was confirmed by RT-qPCR and western blotting. Furthermore, TMPRSS3 was also upregulated in CRC tumor tissues compared to normal tissues. Patients with high TMPRSS3 expression had poor prognosis. Functionally, TMPRSS3 deficiency inhibited cell proliferation and colony formation in CRC cells. TMPRSS3 overexpression in SLC34A2-deficient cells antagonized siSLC34A2-mediated cell cycle inhibition by promoting cyclin E, cyclin A protein expression. Based on these results, our study suggests that SLC34A2 promotes cancer proliferation and cell cycle progression by targeting TMPRSS3 in colorectal cancer cells.

Sanguisorba officinalis L. suppresses 5-fluorouracil-sensitive and-resistant colorectal cancer growth and metastasis via inhibition of the Wnt/β-catenin pathway

BackgroundColorectal cancer (CRC) is a widespread cancer with high morbidity and mortality. Chemoresistance and metastasis are the current challenges for CRC treatment. Sanguisorba officinalis Linn. (called DiYu in Chinese, DY) is a traditional Chinese medicine (TCM) whose root is long used as medicinal part. In our previous study, the aqueous extract of DY could inhibit the Wnt/β-catenin pathway and showed great antitumor effect against CRC. The Wnt/β-catenin pathway is involved in CRC chemoresistance and metastasis. However, there is little study on the antitumor and antimetastatic effects of DY on resistant CRC cells. The aim of this study is to explore the effect of aqueous extract of DY on the growth and metastasis of 5-fluorouracil (5-FU) sensitive and resistant CRC, and to elucidate the underlying molecular mechanism. MethodologyIn this study, cell viability, cell colony formation and apoptosis analyses were performed to verify the in vitro antitumor effect of DY on 5-FU-sensitive and -resistant CRC cells. Next, transwell assays were used to test the inhibition activity of DY on CRC migration and invasion. Western Blotting assays were carried out to identify the molecular mechanism underlying the efficacy of DY extract. Xenograft CRC nude mice model and tumor metastasis model were used to confirm the in vivo antitumor and antimetastatic effects of DY. ResultsDY inhibited cell proliferation and apoptosis via the upregulation of Bax, cleaved-caspase3 and cleaved-PARP proteins and downregulation of Bcl-2 protein. DY also inhibited cell migration and invasion via the downregulation of N-cadherin, vimentin and snail proteins and upregulation of E-cadherin protein, demonstrating that DY suppressed cell metastasis by reversing epithelial-to-mesenchymal transition (EMT) procession. Moreover, the protein expression levels of β-catenin in whole cell, cytoplasm and nucleus were decreased after DY treatment. Taken together, DY suppressed CRC cell growth and metastasis via inhibition of the Wnt pathway. Additionally, DY also demonstrated effective antitumor and anti-metastasis activities in vivo. ConclusionsIn conclusion, DY suppressed the growth and metastasis of 5-FU-sensitive and -resistant CRC via inhibition of the Wnt pathway, which indicated that DY could be a potential drug to treat CRC patients and improve clinic outcome.

65 Identification of frequently presented non-mutated tumor-specific immunogens for the development of both off-the-shelf and personalized vaccines without need for tumor biopsy

BackgroundVaccines have little chance of destroying heterogeneous tumor cells since they rarely induce polyclonal T-cell responses against the tumor. The main challenge is the accurate identification of tumor targets recognizable by T cells. Presently, 6–8% of neoepitopes selected based on the patients‘ tumor biopsies are confirmed as real T cell targets.1 2. To overcome this limitation, we developed a computational platform called Personal Antigen Selection Calculator (PASCal) that identifies frequently presented immunogenic peptide sequences built on HLA-genetics and tumor profile of thousands of real individuals.3 Here we show the performance of PASCal for the identification of both shared and personalized tumor targets in metastatic colorectal cancer (mCRC) and breast cancer subjects.MethodsExpression frequency of the tumor-specific antigens (TSAs) ranked in PASCal’s database (based on 7,548 CRC specimen) was compared to the RNA-sequencing data of CRC tumors obtained from TCGA. Using PASCal, 12 shared PEPIs (epitopes restricted to at least 3 HLA class I alleles of a subject from an in silico cohort) derived from 7 TSAs were selected as frequent targets (calculated probability: average 2.5 [95%CI 2.4–2.8] TSAs/patient). Spontaneous immune responses against each of the twelve 9mer peptides were determined by ELISpot using PBMCs of 10 mCRC subjects who participated in the OBERTO-101 study.4 PEPIs selected for a breast cancer subject based on her HLA genotype were also tested.ResultsEach of the 106 tumors analyzed expressed at least 13, average 15 of the 20 top-ranked TSAs in PASCal’s database confirming their prevalence in CRC. 7/10 subjects had spontaneous CD8+ T-cell responses against at least one peptide selected with PASCal. Each peptide (12/12) was recognized by at least one patient. Patients‘ T-cells reacted with average 3.6/12 (30%) peptides confirming the expression of average 2.8 [95%CI 1.0–4.6] TSAs (n=10). After HLA-matching, among the subjects for whom we could select at least 4 PEPIs (average 5) from the list of 12 peptides (n=6), average 2.5 (50%) peptides were positive. Of the 12 PEPIs selected with PASCal for a breast cancer subject, we detected spontaneous T-cell responses against 9 PEPIs, indicating that at least 75% of the selected peptides were present in the subject’s tumor and were recognized by T-cells.ConclusionsPASCal platform accommodates both tumor- and patient heterogeneity and identifies non-mutated tumor targets that may trigger polyclonal cytotoxic T-cell responses. It is a rapid tool for the design of both off-the-shelf and personalized cancer vaccines negating the need for tumor biopsy.ReferencesWells DK, van Buuren MM, Dang KK, et al. Key parameters of tumor epitope immunogenicity revealed through a consortium approach improve neoantigen prediction. Cell 2020:183(3):818–34.e13.Bulik-Sullivan B, Busby J, Palmer CD, et al. Deep learning using tumor HLA peptide mass spectrometry datasets improves neoantigen identification. Nat Biotech 2018:37:55–63.Somogyi E, Csiszovszki Z, Lorincz O, et al. 1181PDPersonal antigen selection calculator (PASCal) for the design of personal cancer vaccines. Annal Oncol 2019:30(Supplement_5):v480-v81.Hubbard J, Cremolini C, Graham R, et al. P329 PolyPEPI1018 off-the shelf vaccine as add-on to maintenance therapy achieved durable treatment responses in patients with microsatellite-stable metastatic colorectal cancer patients (MSS mCRC). J ImmunoTher Cancer 2019:7(1):282.

APC and TP53 Mutations Predict Cetuximab Sensitivity across Consensus Molecular Subtypes.

Simple SummaryColorectal cancer (CRC) is a major cause of cancer deaths. Cetuximab is an FDA-approved, underutilized therapeutic targeting the epidermal growth factor receptor (EGFR) in metastatic CRC. To date, despite selection of patients with wild-type RAS, it is still difficult to identify patients who may benefit from EGFR inhibitor (e.g., cetuximab) therapy. Our aim is to molecularly classify CRC patients to better identify subpopulations sensitive to EGFR targeted therapy. APC and TP53 are two major tumor suppressor genes in CRC whose mutations contribute to tumor initiation and progression and may identify cetuximab-sensitive tumors. Recently, it has been suggested that the consensus molecular subtype (CMS) classification may be used to help identify cetuximab-sensitive patients. Here, we report an analysis of multiple CRC tumor/PDX/cell line datasets using combined APC and TP53 mutations to refine the CMS classification to better predict responses to cetuximab to improve patient outcomes.Recently, it was suggested that consensus molecular subtyping (CMS) may aide in predicting response to EGFR inhibitor (cetuximab) therapies. We recently identified that APC and TP53 as two tumor suppressor genes, when mutated, may enhance cetuximab sensitivity and may represent easily measured biomarkers in tumors or blood. Our study aimed to use APC and TP53 mutations (AP) to refine the CMS classification to better predict responses to cetuximab. In total, 433 CRC tumors were classified into CMS1-4 subtypes. The cetuximab sensitivity (CTX-S) signature scores of AP vs. non-AP tumors were determined across each of the CMS classes. Tumors harboring combined AP mutations were predominantly enriched in the CMS2 class, and to a lesser degree, in the CMS4 class. On the other hand, AP mutated CRCs had significantly higher CTX-S scores compared to non-AP CRCs across all CMS classes. Similar results were also obtained in independent TCGA tumor collections (n = 531) and in PDMR PDX/PDO/PDC models (n = 477). In addition, the in vitro cetuximab growth inhibition was preferentially associated with the CMS2 cell lines harboring A/P genotypes. In conclusion, the AP mutation signature represents a convenient biomarker that refines the CMS classification to identify CRC subpopulations predicted to be sensitive to EGFR targeted therapies.

Understanding the regulation of β-catenin expression and activity in colorectal cancer carcinogenesis: beyond destruction complex.

Aberrant Wnt/β-catenin signaling is central to colorectal cancer carcinogenesis. The well-known potential of targeting the canonical Wnt signaling pathway for the treatment of CRC is largely attributed to the ability of this pathway to regulate various cellular processes such as cell proliferation, metastasis, drug resistance, immune response, apoptosis, and cellular metabolism. However, with the current approach of targeting this pathway, none of the Wnt-targeted agents have been successfully implicated in clinical practice. Instead of using classical approaches to target this pathway, there is a growing need to find new and modified approaches to achieve the same. For this, a better understanding of the regulation of β-catenin, a major effector of the canonical Wnt pathway is a must. The present review addresses the importance of understanding the regulation of β-catenin beyond the destruction complex. Few recently discovered β-catenin regulators such as ZNF281, TTPAL, AGR2, ARHGAP25, TREM2, and TIPE1 showed significant potential in regulating the development of CRC through modulation of the Wnt/β-catenin signaling pathway in both in vitro and in vivo studies. Although the expression and activity of β-catenin is influenced by many protein regulators, the abovementioned proteins not only influence its expression and activation but are also directly involved in the development of CRC and various other solid tumors. Therefore, we hypothesise that focusing the current research on finding the detailed mechanism of action of these regulators may assist in providing with a better treatment approach or improve the current therapeutic regimens.

Tumor suppressive effect of scavenger receptor class A member 5 overexpression in colorectal cancer by regulating PI3K/AKT/mTOR pathway

BackgroundColorectal cancer (CRC) exhibits high risks of morbidity and mortality.ObjectiveTo investigate the effect of scavenger receptor class A member 5 (SCRAR5) on CRC and its mechanism on modulation of cancer development.MethodsThe SCRAR5 expression in four kinds of CRC cell lines (SW620, SW480, HT29, and HCT116) was measured by quantitative PCR and western blotting, respectively. The effects of SCRAR5 abnormal expression on cell proliferation, apoptosis, and migration were analyzed by CCK-8 assay, EdU assay, colony-forming assay, flow cytometry assay, Transwell assay and wound healing assay, respectively. Meanwhile, the involvements of PI3K/AKT/mTOR pathway with the role of SCRAR5 were investigated by western blotting. Afterwards, the in vivo effects of SCRAR5 abnormal expression on CRC xenograft mice were finally investigated by evaluating tumor volume, apoptosis and Ki67 expression.ResultsSCRAR5 was lowly expressed in CRC cell lines, especially SW480 cells. Up-regulation of SCRAR5 significantly promoted cell apoptosis, reduced cell proliferation and migration in SW480 cells. Notably, SCRAR5 overexpression obviously inhibited the phosphorylation levels of PI3K, AKT, and mTOR. Reversely, SCRAR5 silence exhibited promoting effects on HT29 cells. Consistently, in vivo experiments also revealed that SCRAR5 overexpression remarkably suppressed tumor volume and Ki67 expression, as well as promoted cell apoptosis.ConclusionsOverall, up-regulating of SCRAR5 obviously inhibited CRC tumor growth in vitro and in vivo, which might be related to PI3K/AKT/mTOR pathway.

Abstract CT192: Phase IIa open-label clinical study of intratumoural administration of BO-112 in combination with pembrolizumab in subjects with liver metastasis from colorectal cancer or gastric/gastro-oesophageal junction cancer

Abstract Protocol tittle: Study of BO-112 with pembrolizumab for colorectal or gastric/GEJ cancer with liver metastasis.Background: Gastric (GC), oesophagogastric junction (EGJC) and colorectal tumors (CRC) with microsatellite stability (MSS) are poorly responders to PD(L)-1 inhibition, due to low CD8+ T cell infiltration and PD-L1 expression. Therefore, modulation of the tumor microenvironment (TME) could increase disease control. In these tumors the presence of liver lesions is difficult to control because of the hepatic immune tolerance. Control of the hepatic disease could increase survival.BO-112 is a non-coding dsRNA agonist of TLR3, MDA5 and RIG-I which activates the innate and adaptative immune response, inducing apoptosis and immunogenic cell death, with a local and a systemic effect. A prior Phase I trial showed that the combination of pembrolizumab and intratumoral (IT) BO-112 has a good safety profile and encouraging activity. Study design: This is a single arm phase IIa trial to assess the efficacy of intrahepatic IT BO-112 and iv pembrolizumab in 3W cycles in patients with MSS CRC, GC or EGJ tumors. Up to 69 patients with at least one liver lesion and 2 prior lines for CRC and 1 for GC/EGJC will be enrolled. Primary endpoints: ORR and related TEAEs ≥ grade 3. Secondary endpoints: ORR (iRECIST), PFS, 6-months OS and safety. Exploratory endpoint: Changes in TME (PD-L1 expression and CD8+ T cell infiltration) from baseline to C2D1.Results: A total of 11 CRC and 7 GC/EGJC patients were enrolled since July 2020. This abstract focuses on the CRC patients´ biomarker expression. These patients had low PD-L1 CPS (combined positive score) expression and CD8+ T cell infiltration with a median value of 5 and 4%, respectively, in the TME at baseline. Following two IT BO-112 injections, an important increase in PD-L1 expression and CD8+ T cell infiltration was observed in 5 and 7 patients, respectively. PD-L1 CPS median value increased to 37.9 while CD8+ T cell infiltration median values raised to 12.9%.Conclusions: A meaningful increase in PD-L1 expression and CD8+ T cell infiltration was achieved in MSS CRC patients after one cycle of BO-112-pembrolizumab. Table 1.Baseline characteristics and TME changesBaseline characteristicsCRC N=11Demographics-Sex-Male-Female-Age (mean, range)7 (63.6%)4 (36.4%)55 (38-74)Location of primary tumor-Right colon-Left colon2 (36.4%)7 (63.6%)Presence of extrahepatic disease-No-YesLocation of the extrahepatic disease-Lungs-Lymph nodes-Ohers (bone, adrenal gland, peritoneum, pancreas)2 (18.2%)9 (81.8%)6 (54.5%)5 (45.5%)1 (9.1%)Molecular characteristics:-MMR status-MSS-KRAS-Wild type-Mutant -PD-L1-CPS <1%-CPS ≥ 1%11 (100%)4 (36.4%)7 (63.6%)1 (11.1%)10 (88.9%)Number of prior anticancer therapies-1 PACT line-2 PACT lines-3 PACT lines-4 PACT lines0(0%)6 (54.5%)3 (27.3%)2 (18.2%)Time to progression on prior treatment (months)-Mean, range-Median6.5 (1.2-27)3.2Number of the injected lesions1 (100%)Size of the injected lesión-Mean, range-Median41.6 mm (20-75) 28 mmBiomarker expression in TME (PD-L1 measured on TPS, TAIC and CPS)CRC N=9/11 (no available paired samples from 2 patients)PD-L1 CPS BaselineMean, range Median18.3 (0-80) 5T-CD8 cells infiltration BaselineMean, rangeMedian7.7%(2-25%) 4%PD-L1 CPS Week 4Mean, range Median37.9(1-90) 22T-CD8 infiltration Week 4 Mean, range Median12.9% (2 -25%) 15% Citation Format: Mariano Ponz-Sarvisé, Elena Élez, Andrés Muñoz, Marc Van den Eynde, Antonio Gaetano Rampoldi, Alain Hendlisz, Hans Prenen, Mercedes Rodríguez, María Teresa Cano, Marya Chaney, Helena Escuin, Vanesa Pons, Marisol Quintero, Andrés Cervantes. Phase IIa open-label clinical study of intratumoural administration of BO-112 in combination with pembrolizumab in subjects with liver metastasis from colorectal cancer or gastric/gastro-oesophageal junction cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT192.

Abstract 345: An integrative approach of image analysis and transcriptome profiling to explore potential predictive biomarkers for TGF-beta blockade therapy

Abstract Background: The pattern of tumor infiltrating lymphocytes (TILs) in the tumor microenvironment (TME) can be classified as immune-inflamed, -excluded and -desert and may be a critical factor for immunotherapy efficacy and disease course of solid malignancies. Recent studies have identified TGFβ activity and signaling in the TME as a determinant of cytotoxic T cell exclusion and poor response to PD-1/PD-L1 blockade. Our goal was to identify tumors with immune-excluded phenotype with high levels of TGFβ activity, as predictors of response to TGFβ inhibition in checkpoint refractory tumors to make “cold” (immune excluded and desert) tumors “hot”. We applied an integrative approach using image analysis together with gene expression profiling to quantify distribution of TILs and characterize the associated TGFβ pathway activity. Methods: A multiplex fluorescent IHC assay was developed for PanCK/CD3/CD8 by Indivumed GmbH (Germany) and applied to a collection of archival biopsies including Bladder (n=20), CRC (n=29), HNSCC (n=19), Gastric (n=18) and Ovarian (n=19) cancers. We utilized digital pathology image analysis to classify the immune phenotypes based on annotation of the images by a pathologist. Computational imaging methods were used to localize the CD3+ and CD8+ lymphocytes and discern their proximity to tumor cells. RNAseq was performed on the 29 CRC tumors to investigate the prominent biological features associated with infiltration phenotypes, as well as the correlation between these phenotypes and a TGFβ activation signature derived from TGFβ-stimulated versus naïve cancer cell lines. Results: Analysis of T cell spatial distribution in the solid tumor biopsies (N=105) revealed substantial differences in the distribution of the infiltration phenotypes by tumor type. Computational assessments achieved 100% concordance with the pathologist assessment for tumors with the inflamed and desert phenotype but just 70% concordance with the excluded phenotype. Additionally, the distribution of topographies differs between cancer types, i.e., CRC and bladder cancer tend to be immune-excluded. The TIL score was negatively correlated with TGFβ pathway activation, together with elevated TGFβ signaling activity observed in “cold” tumors. Conclusion: Our image analysis platform was able to identify these T cell topographies in TME in the five tumor types. The robust association between TGFβ gene signature and immune phenotypes further demonstrates their potential as predictive biomarkers to identify appropriate patients that may benefit from TGFβ blockade. Citation Format: Robert Pomponio, Qi Tang, Anthony Mei, Anne Caron, Bema Coulibaly, Joachim Theihaber, Maximilian Rogers-Grazado, Tun Tun Lin, Rui Wang. An integrative approach of image analysis and transcriptome profiling to explore potential predictive biomarkers for TGF-beta blockade therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 345.

Abstract 1271: In vitro and in vivo characterization of BI 1823911 - a novel KRASG12C selective small molecule inhibitor

Abstract KRASG12C mutations are predominantly found in non-small cell lung cancer (NSCLC, 13%), in colorectal cancer (CRC, 3%), and with a lower prevalence in pancreatic ductal adenocarcinoma (PDAC, 1%). The amino acid exchange at position 12 from glycine to cysteine renders RAS insensitive to GAP-catalyzed hydrolysis but not to intrinsic hydrolysis and consequently, KRASG12C is still dependent on GEF stimulation to achieve full activation. The active GTP-loaded form of KRASG12C is favored and leads to activation of downstream signaling and proliferation. A number of recent publications has shown that targeting this mutant form of KRAS, using several covalent KRASG12C inhibitors binding to the inactive GDP-KRASG12C form, leads to anti-proliferative effects and induction of apoptosis in KRASG12C mutant cancer cell lines, CDX and PDX models. Early clinical data for AMG 510 and MRTX849 revealed a response rate of 35-45% in NSCLC and of 7-17% in CRC patients. Here, we show that BI 1823911 has potent anti-proliferative activity in a panel of KRASG12C mutant cancer cell lines with higher or similar potency compared to these two most advanced compounds in clinical development. In a panel of KRASG12C NSCLC cell lines, treatment with BI 1823911 results in downregulation of MAPK pathway-responsive genes, such as DUSP6 and CCND1, and the extent of pathway modulation correlates with sensitivity. Likewise, we observe strong and sustained inactivation of the MAPK pathway at the protein level using p-ERK as a pharmacodynamic (PD) biomarker. A MIA PaCa-2 cell line-derived pancreatic cancer xenograft model was selected for extensive PK/PD/efficacy analyses in vivo. Briefly, BI 1823911 tested at 60 mg/kg showed similar anti-tumor activity compared to both competitor compounds dosed at clinically relevant exposures. Results of the ongoing in-depth PK/PD/efficacy analysis will be shared. Furthermore, BI 1823911 was tested with a daily oral dose of 60 mg/kg in a panel of NSCLC or CRC CDX or PDX mouse models and showed comparable efficacy to AMG 510 and MRTX849, respectively. Preclinical and clinical data suggest that monotherapy with a KRASG12C inhibitor will not be sufficient to achieve durable response. Combination therapy of a KRASG12C inhibitor may therefore lead to enhanced anti-tumor efficacy and may address adaptive resistance mechanisms. Therefore, we selected a panel of KRASG12C mutant cancer cell lines and tested a large set of compounds in combination with BI 1823911 to identify synergistic anti-proliferative activity. Among other MAPK and PI3K pathway inhibitors, a SOS1::KRAS inhibitor was confirmed as promising combination partner. We will show results from in vitro and in vivo combination studies in NSCLC and CRC tumor models that show deep and durable responses upon combination of BI 1823911 with SOS1::KRAS inhibitor BI 1701963 providing a strong rationale for clinical investigation of this combination. Citation Format: Fabio Savarese, Andreas Gollner, Dorothea Rudolph, Jesse Lipp, Johannes Popow, Marco H. Hofmann, Heribert Arnhof, Jörg Rinnenthal, Francesca Trapani, Michael Gmachl, Daniel Gerlach, Joachim Broeker, Peter Ettmayer, Andreas Mantoulidis, Jason Phan, Christian A. Smethurst, Matthias Treu, Alex G. Waterson, Hengyu Lu, Annette Machado, Joseph Daniele, Stephan W. Fesik, Christopher P. Vellano, Timothy P. Heffernan, Joseph R. Marszalek, Darryl B. McConnell, Mark Petronczki, Norbert Kraut, Irene C. Waizenegger. In vitro and in vivo characterization of BI 1823911 - a novel KRASG12C selective small molecule inhibitor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1271.

Suppression of HSF1 activity by wildtype p53 creates a driving force for p53 loss-of-heterozygosity

The vast majority of human tumors with p53 mutations undergo loss of the remaining wildtype p53 allele (loss-of-heterozygosity, p53LOH). p53LOH has watershed significance in promoting tumor progression. However, driving forces for p53LOH are poorly understood. Here we identify the repressive WTp53–HSF1 axis as one driver of p53LOH. We find that the WTp53 allele in AOM/DSS chemically-induced colorectal tumors (CRC) of p53R248Q/+ mice retains partial activity and represses heat-shock factor 1 (HSF1), the master regulator of the proteotoxic stress response (HSR) that is ubiquitously activated in cancer. HSR is critical for stabilizing oncogenic proteins including mutp53. WTp53-retaining CRC tumors, tumor-derived organoids and human CRC cells all suppress the tumor-promoting HSF1 program. Mechanistically, retained WTp53 activates CDKN1A/p21, causing cell cycle inhibition and suppression of E2F target MLK3. MLK3 links cell cycle with the MAPK stress pathway to activate the HSR response. In p53R248Q/+ tumors WTp53 activation by constitutive stress represses MLK3, thereby weakening the MAPK-HSF1 response necessary for tumor survival. This creates selection pressure for p53LOH which eliminates the repressive WTp53-MAPK-HSF1 axis and unleashes tumor-promoting HSF1 functions, inducing mutp53 stabilization enabling invasion.

HER2 positivity as a biomarker for poor prognosis and unresponsiveness to anti-EGFR therapy in colorectal cancer.

To investigate the role of HER2 positivity in prognosis and unresponsiveness to anti-EGFR therapy for colorectal cancer. Patients who underwent primary CRC tumor resection were included. HER2 status of CRC was confirmed by immunohistochemistry and fluorescence in situ hybridization tests. Comparison of survival analysis between HER2 positivity and negativity was evaluated by a stratified log-rank test and summarized with the use of Kaplan-Meier and Cox proportional hazards methods. The treatment effects of cetuximab were further compared in full subgroup analyses. 1240 patients were enrolled, including 763 with stage I-III CRC and 477 with stage IV CRC. 57 (4.6%) CRC patients presented HER2 positivity in the entire cohort. The survival analysis showed that patients with HER2 positivity had significantly worse disease-free survival and overall survival in stage III and IV CRC. The multivariable analysis also confirmed that HER2 positivity was a significantly independent risk factor in stage III and IV CRC. Univariate and multivariable survival analysis showed no prognostic significance of HER2 positivity in stage I-II CRC patients. Prespecified subgroup analysis showed no favorable trends in progression-free survival and overall survival for cetuximab in the patients with HER2 positivity, KRAS/NRAS/BRAF wild-type metastatic CRC (interaction P values = 0.005 and 0.014). For stage III and IV CRC patients, HER2 positivity was confirmed as an independent prognostic risk factor. It could help predict the unresponsiveness to anti-EGFR therapy for metastatic CRC.

Verticillin A increases the BIMEL/MCL-1 ratio to overcome ABT-737-resistance in human colon cancer cells by targeting the MEK/ERK pathway

ABT-737, a small molecule BH-3 mimetic, is less effective against human colon cancers due to its resistance. Verticillin A is a natural compound, which was previously purified from verticillium-infected mushrooms. Hence, we aimed at overcoming the ABT737 resistance observed in CRC tumors by combining Verticillin A with ABT-737 and figuring out the potential mechanism. In this study, we observed that Verticillin A could sensitize colon cancer to ABT-737-induced cell death through induction of mitochondrial-dependent apoptosis. Verticillin A could significantly increase the BIMEL/MCL-1 ratio to overcome ABT737 resistance through the suppression of the MEK/ERK pathway. In addition, up-regulation of BIM protein levels to activate BAX translocation results in apoptosis induction. Altogether, our work suggested the potential application of Verticillin A as a MEK inhibitor in BH3-mimetic-based therapy.

Identification of DNA methylation biomarkers for risk of liver metastasis in early-stage colorectal cancer

BackgroundLiver metastases can occur even in CRC patients who underwent curative surgery. While evidence suggested that adjuvant chemotherapy can help to reduce the occurrence of liver metastases for certain patients, it is not a recommended routine as the side effects outweigh the potential benefits, especially in Stage II CRC patients. This study aims to construct a model for predicting liver metastasis risk using differential methylation signals in primary CRC tumors, which can facilitate the decision for adjuvant chemotherapy.MethodsFifty-nine stage I/II and IV CRC patients were enrolled. Primary tumor, adjacent normal tissue, and metastatic tumor tissues were subject to targeted bisulfite sequencing for DNA methylation. The Least Absolute Shrinkage and Selection Operator (LASSO) algorithm was used to identify potential DMRs for predicting liver metastasis of CRC.ResultsWe identified a total of 241,573 DMRs by comparing the DNA methylation profile of primary tumors of stage II patients who developed metastasis to those who were metastasis-free during the follow up period. 213 DMRs were associated with poor prognosis, among which 182 DMRS were found to be hypermethylated in the primary tumor of patients with metastases. Furthermore, by using the LASSO regression model, we identified 23 DMRs that contributed to a high probability of liver metastasis of CRC. The leave-one-out cross validation (LOOCV) was used to evaluate model predictive performance at an AUC of 0.701. In particular, 7 out of those 23 DMRs were found to be in the promoter region of genes that were previously reported prognostic biomarkers in diverse tumor types, including TNNI2, PAX8, GUF1, KLF4, EVI2B, CEP112, and long non-coding RNA AC011298. In addition, the model was also able to distinguish metastases of different sites (liver or lung) at an AUC of 0.933.ConclusionWe have identified DNA methylation biomarkers associated with the risk of cancer liver metastasis in early-stage CRC patients. A risk prediction model based on those epigenetic markers was proposed for outcome assessment.

Analysis of Copy Number Variations in Solid Tumors Using a Next Generation Sequencing Custom Panel

Somatic copy number variations (CNV; i.e., amplifications and deletions) have been implicated in the origin and development of multiple cancers and some of these aberrations are designated targets for therapies. Although FISH is still considered the gold standard for CNV detection, the increasing number of potentially druggable amplifications to be assessed makes a gene-by-gene approach time- and tissue-consuming. Here we investigated the potential of next generation sequencing (NGS) custom panels to simultaneously determine CNVs across FFPE solid tumor samples. DNA was purified from cell lines and FFPE samples and analyzed by NGS sequencing using a 20-gene custom panel in the GeneReader Platform®. CNVs were identified using an in-house algorithm based on the UMI read coverage. Retrospective validation of in-house algorithm to identify CNVs showed 97.1% concordance rate with the NGS custom panel. The prospective analysis was performed in a cohort of 243 FFPE samples from patients arriving at our hospital, which included 74 NSCLC tumors, 148 CRC tumors, and 21 other tumors. Of them, 33% presented CNVs by NGS and in 14 cases (5.9%) the CNV was the only alteration detected. We have identified CNV alterations in about one-third of our cohort, including FGFR1, CDK6, CDK4, EGFR, MET, ERBB2, BRAF, or KRAS. Our work highlights the need to include CNV testing as a part of routine NGS analysis in order to uncover clinically relevant gene amplifications that can guide the selection of therapies.

Multi-omics characterization of left-right colorectal cancer.

3542 Background: Right (R) vs left (L) sided colorectal cancers are clinically distinguishable based on prognosis and response to certain therapies, but as of yet, limited data have emerged to explain these differences. The science of molecular testing has evolved rapidly. Enabled by improved technologies and computing power, it is now feasible to obtain to systematic multi-omic datasets covering DNA, RNA, proteins, phospho-proteins and metabolomics on large numbers of patients. Multi-omic analysis can further define disease specific subgroups but pre-analytic quality of the tissues (ischemia time) and comparison to normal tissue controls is paramount to optimize results. Methods: Following informed consent, 450 colorectal cancer primary tumors and paired normal tissues were collected following an SOP to minimize ischemia time, and were analyzed using comprehensive genomics, transcriptomics, proteomics, phosphoproteomics, morphology and annual clinical information. Right (C18.0,2,3) and left (C18.6,7) CRC tumors, normal tissue were compared using machine learning tools to unravel the molecular mechanisms that underpin these clinically distinguishable phenotypes as well as correlating with known genomic metrics such MSI and KRAS mutation status. Results: Through leveraging the tumor and paired normal patient samples, systematic differences between left and right tumor samples were observed including specific molecular events associated with these anatomical differences. The detailed results will be presented at the meeting. Conclusions: Progress in precision medicine requires the inclusion of multi-omics which in turn requires changes to our current SOPs of tissue collection. The ability to define molecular distinctions such as between R and L colon cancer will permit the rapid discovery of clinically useful prognostic and predictive markers, dramatically adding to our fundamental understanding to colon cancer biology. Future work will focus on the discovery of novel targets and signatures, creating innovative tools that depict multi-omic results for clinicians.

Performance of Next-Generation Sequencing for the Detection of Microsatellite Instability in Colorectal Cancer With Deficient DNA Mismatch Repair

Next-generation sequencing (NGS) was recently approved by the United States Food and Drug Administration to detect microsatellite instability (MSI) arising from defective mismatch repair (dMMR) in patients with metastatic colorectal cancer (mCRC) before treatment with immune checkpoint inhibitors (ICI). In this study, we aimed to evaluate and improve the performance of NGS to identify MSI in CRC, especially dMMR mCRC treated with ICI. CRC samples used in this post hoc study were reassessed centrally for MSI and dMMR status using the reference methods of pentaplex polymerase chain reaction and immunohistochemistry. Whole-exome sequencing (WES) was used to evaluate MSISensor, the Food and Drug Administration-approved and NGS-based method for assessment of MSI. This was performed in (1) a prospective, multicenter cohort of 102 patients with mCRC (C1; 25 dMMR/MSI, 24 treated with ICI) from clinical trials NCT02840604 and NCT033501260, (2) an independent retrospective, multicenter cohort of 113 patients (C2; 25 mCRC, 88 non-mCRC, all dMMR/MSI untreated with ICI), and (3) a publicly available series of 118 patients with CRC from The Cancer Genome Atlas (C3; 51 dMMR/MSI). A new NGS-based algorithm, namely MSICare, was developed. Its performance for assessment of MSI was compared with MSISensor in C1, C2, and C3 at the exome level or after downsampling sequencing data to the MSK-IMPACT gene panel. MSICare was validated in an additional retrospective, multicenter cohort (C4) of 152 patients with new CRC (137 dMMR/MSI) enriched in tumors deficient in MSH6 (n= 35) and PMS2 (n= 9) after targeted sequencing of samples with an optimized set of microsatellite markers (MSIDIAG). At the exome level, MSISensor was highly specific but failed to diagnose MSI in 16% of MSI/dMMR mCRC from C1 (4 of 25; sensitivity, 84%; 95% confidence interval [CI], 63.9%-95.5%), 32% of mCRC (8 of 25; sensitivity, 68%; 95% CI, 46.5%-85.1%), and 9.1% of non-mCRC from C2 (8 of 88; sensitivity, 90.9%; 95% CI, 82.9%-96%), and 9.8% of CRC from C3 (5 of 51; sensitivity, 90.2%; 95% CI, 78.6%-96.7%). Misdiagnosis included 4 mCRCs treated with ICI, of which 3 showed an overall response rate without progression at this date. At the exome level, reevaluation of the MSI genomic signal using MSICare detected 100% of cases with true MSI status among C1 and C2. Further validation of MSICare was obtained in CRC tumors from C3, with 96.1% concordance for MSI status. Whereas misdiagnosis with MSISensor even increased when analyzing downsampled WES data from C1 and C2 with microsatellite markers restricted to the MSK-IMPACT gene panel (sensitivity, 72.5%; 95% CI, 64.2%-79.7%), particularly in the MSH6-deficient setting, MSICare sensitivity and specificity remained optimal (100%). Similar results were obtained with MSICare after targeted NGS of tumors from C4 with the optimized microsatellite panel MSIDIAG (sensitivity, 99.3%; 95% CI, 96%-100%; specificity, 100%). In contrast to MSISensor, the new MSICare test we propose performs at least as efficiently as the reference method, MSI polymerase chain reaction, to detect MSI in CRC regardless of the defective MMR protein under both WES and targeted NGS conditions. We suggest MSICare may rapidly become a reference method for NGS-based testing of MSI in CRC, especially in mCRC, where accurate MSI status is required before the prescription of ICI.

61892 Systemic TLR3-targeting Combinatorial Chemokine Modulation Sensitizes Murine Tumors to PD-1 Blockade

ABSTRACT IMPACT: This work will lead to improved efficacy of immunotherapy directly impacting the survival of patients with hard to treat cancers. OBJECTIVES/GOALS: Immune checkpoint inhibitors (ICI) are most effective against ‘hot’ tumors highly infiltrated with cytotoxic T lymphocytes (CTLs) but have not worked well in poorly infiltrated ‘cold’ tumors. Thus, we are working to achieve a pretreatment regimen that will create a favorable immune profile allowing more effective ?PD-1 therapy. METHODS/STUDY POPULATION: BALB/c or C57BL/6 mice were inoculated with CRC murine cells CT26 or MC38, respectively. Mice were inoculated by two injection types: subcutaneous (SC), for systemic therapy, or intraperitoneal (IP), for local therapy. Tumor-bearing mice were given a two dose course of CKM consisting of IFN-? and rintatolimod via IP injection. Following CKM administration, mice were treated with three doses of ?PD-1 via IP injection. Mice were monitored for the kinetics of tumor growth and survival following treatment. The tumor microenvironment of treated mice was analyzed for production of chemokines, inflammatory cytokines and immune cell infiltration. RESULTS/ANTICIPATED RESULTS: CKM consisting of combination IFN-? and rintatolimod, but neither monotherapy alone, sensitized murine CRC tumors to subsequent ?PD-1 treatment. In both CT26 and MC38 tumor-bearing mice, tumor growth was hindered by CKM plus ?PD-1 treatment, independently on the route of treatment (local or systemic). Mice which experienced complete tumor regression were protected from re-challenge with a dose of tumor cells double that of the initial inoculation. Sensitizing tumors to ?PD-1 did not require intratumoral CKM administration and was observed with systemic application at distant sites. In accordance with these observations we expect that systemic CKM will induce strong increases of total and tumor-specific CTL counts in the tumor tissues as measured by both PCR and flow cytometry. DISCUSSION/SIGNIFICANCE OF FINDINGS: CKM sensitizing cold tumors to ?PD-1 indicates that intratumoral CTLs are an important factor dictating therapeutic effectiveness, independent of other factors such as tumor mutational load. The benefit of the sequential short-term CKM followed by routine ?PD-1 make this strategy feasible for rapid inclusion of into routine immunotherapy plans.

Recent Advances in Our Knowledge of mCRC Tumor Biology and Genetics: A Focus on Targeted Therapy Development.

Metastatic colorectal cancer (mCRC) remains a highly lethal malignancy although considerable progress has resulted from characterizing molecular alterations such as RAS mutation status and extent of microsatellite instability (MSI) to guide optimal use of available therapies. The availability of gene expression profiling, next generation sequencing technologies, proteomics analysis and other technologies provides high resolution information on individual tumors, including metastatic lesions to better define intra-tumor and inter-tumor heterogeneity. Recent literature applying this information to further customize personalized therapies is reviewed. Current biomarker-based stratification used to select optimal therapy that is personalized to the mutation profile of individual tumors is described. Recent literature using whole exome sequencing of metastatic lesions and primary CRC tumors and other advanced technologies to more fully elucidate the tumor biology specific to mCRC sub-types and to develop more precise therapies that improve outcomes is also reviewed.

SGNTUC-019: Phase II basket study of tucatinib (TUC) and trastuzumab (Tras) in previously treated solid tumors with HER2 alterations: Urothelial cancer cohort (trial in progress).

TPS499 Background: Tucatinib (TUC), a highly selective HER2-directed TKI recently approved for HER2 overexpressed/amplified (HER2+) metastatic breast cancer, is being developed as a novel therapy for patients (pts) with metastatic CRC, gastric cancer, and other GI tumors. In xenograft models of HER2+ and HER2-mutated (HER2-mut) tumors, dual targeting of HER2 with TUC and trastuzumab (Tras) showed superior activity to either agent alone. Despite the development of several new therapies for metastatic urothelial cancer, response durations generally remain short and the great majority of pts succumb to the disease, highlighting the need for therapeutic approaches. Given that 20-30% of urothelial cancers have molecular alterations of the ErbB family, TUC in combination with Tras warrants further evaluation in this population. The SGNTUC-019 basket study is evaluating TUC in combination with Tras in pts with HER2+ or HER2-mut solid tumors, including a cohort of pts with locally advanced or metastatic (LAUM) urothelial cancer. Methods: SGNTUC-019 (NCT04579380) is a multi-cohort, open-label, international phase II study evaluating pts with previously treated solid tumors displaying HER2 overexpression/amplification or activating mutations. Eligible pts must have HER2+ or HER2-mut LAUM solid tumors, with progression on or after the last systemic therapy for advanced disease. Pts must be ≥18 years old, with ECOG PS ≤1, adequate hepatic, hematological, renal, coagulatory, and cardiac function, and no prior exposure to HER2-directed therapy. For eligibility, HER2 alterations can be demonstrated by HER2 overexpression/amplification in tumor tissue by prior IHC/ISH (IHC 3+/signal ratio ≥2.0 or gene copy number >6), or by HER2 amplification/mutation in a prior or on-study NGS assay of ctDNA or prior tissue NGS assay. The HER2 overexpression/amplification urothelial cancer cohort will enroll 12 RECIST 1.1 response-evaluable pts. If ≥2 responses are observed, the cohort will be expanded to a total of 30 pts. Pts with HER2-mut urothelial cancer will be enrolled in a cohort of 30 pts for all solid tumor types except breast cancer and non-squamous NSCLC. If justified, a separate cohort for HER2-mut urothelial cancer may be opened. The primary objective is antitumor activity in each cohort, with confirmed ORR as primary endpoint, and disease control rate, duration of response, PFS, and OS as secondary endpoints. Pts will receive TUC 300 mg orally twice daily and Tras 8 mg/kg IV on Cycle 1 Day 1 and 6 mg/kg q21 days from Cycle 2 Day 1. Disease assessments per RECIST 1.1 will occur q6 weeks for 24 weeks, then q12 weeks. Trough concentrations of TUC will be evaluated in all pts in Cycles 2-6, with a peak concentration sampled in Cycle 3. Quality of life will be evaluated q2 cycle using EQ-5D-5L. Sites will open in the US, EU, and Asia; enrollment is anticipated to begin in Dec 2020. Clinical trial information: NCT04579380.