MSS Colorectal Cancer Research Articles

SHR-8068 combined with adebrelimab and bevacizumab in the treatment of refractory advanced colorectal cancer: study protocol for a single-arm, phase Ib/II study.

The third-line treatment for refractory colorectal cancer (CRC) has limited efficacy. This study aimed to evaluate the safety and efficacy of SHR-8068 (an anti-CTLA-4 antibody), combined with adebrelimab (an anti-PD-L1 antibody), and bevacizumab in refractory non-microsatellite instability-high (MSI-H) or proficient mismatch repair (pMMR) CRC. This study is a prospective, open-label, single-center phase Ib/II clinical trial. Patients with pathologically confirmed pMMR/non-MSI-H metastatic colorectal adenocarcinoma who have failed ≥2 lines prior standard systemic treatments will be enrolled (n=36). The Ib phase will evaluate two dosing regimens of SHR-8068 in combination therapy (n=9 each dosage): SHR-8068 (1 mg per kilogram, every six weeks, intravenously) or SHR-8068 (4 mg per kilogram, every twelve weeks, intravenously) combined with adebrelimab (1200 mg, every three weeks, intravenously) and bevacizumab (7.5 mg per kilogram, every three weeks, intravenously). The efficacy and adverse events (AEs) of these regimens will be assessed to determine the recommended phase II dose (RP2D) of SHR-8068. Those of RP2D group from the phase Ib will be included in the phase II. The study will go to include 18 additional patients according to the one-sample log-rank test design in the phase II. The primary endpoint of the Ib phase is safety, with secondary endpoints including the objective response rate (ORR), progression-free survival (PFS), overall survival (OS), disease control rate (DCR), and quality of life (QOL). The primary endpoint for phase II was PFS, with secondary endpoints including ORR, OS, DCR, safety, and QOL. Identifying biomarkers to predict the efficacy of this regimen is the exploratory study endpoint. This proof-of-concept study would provide safety and efficacy signals of this novel combination treatment for the MSS CRCs in the late-line setting. And it may offer new insights on the clinical application of dual immunotherapy combined with anti-angiogenic therapy in the MSS CRC.

Integrative analysis of the immunological significances of guanylate binding protein family genes in microsatellite stability colorectal cancer

BackgroundMicrosatellite stability (MSS) colorectal cancer (CRC) has poor sensitivity to immunotherapy and its underlying mechanisms are still unclear. Guanylate binding proteins (GBPs) are a family of GTPase involving innate immune responses by providing defense against invading microbes and pathogens. However, the immunological significances of GBPs in MSS CRC remain unknown. MethodsWe utilized bioinformatic tools to comprehensively analysis the expression pattern, clinical relevance, prognostic value, biological function, and immunoregulation effect of distinct GBP members in MSS CRC. ResultsThe expression of all seven GBPs in MSS samples are remarkably decreased compared to microsatellite instability-high (MSI-H) samples. Among them, GBP1/2/4/5 are obviously correlated with distant metastasis status. High expression of GBP1/4/5/6 was remarkably related to favorable overall survival (OS) and progression-free survival (PFS) in CRC patients with MSS tumor. Subsequent enrichment analysis revealed that Interferon-gamma (IFN-γ) and NOD-like receptor signaling are the most relevant functions. Besides, the expression patterns of GBPs are remarkably associated with several tumor infiltrated immune cells (e.g. regulatory T cells, CD4+ T cells, and macrophages) and diverse immunoregulatory molecules (e.g. immune checkpoint biomarkers (ICBs) and major histocompatibility complex (MHC) molecules). Moreover, high GBP1/2/4/5 expression predicted better immunotherapy responsiveness in immunotherapy cohorts. ConclusionThese findings might provide novel insights for the identification of therapeutic targets and potential prognostic biomarkers of GBP family in CRC with MSS samples.

The impact of metformin on clinical outcomes of metastatic colorectal cancer with known molecular profile treated with cytotoxic chemotherapy or immune checkpoint inhibitor.

e15580 Background: Colorectal cancer (CRC) is the third most common cancer in the US, with a dismal 5-year OS of 13% in mCRC. Concomitant metformin with chemotherapy or immune checkpoint inhibitors (ICIs) revealed improved outcomes in various cancers. Metformin's anti-cancer effects stem its effects on cancer metabolism, cell cycle modulation, cancer stem cells, gut microbiota, immunomodulatory properties. The aim of this retrospective study was to study the impact of concomitant metformin use with the type of systemic therapy (chemotherapy or ICIs) in CRC. Methods: CRC tumors were analyzed by NGS of DNA (592-gene) and RNA (whole transcriptome) at Caris Life Sciences. MSS was assessed by NGS, with MSI-H and MSS patients subcategorized by concomitant metformin use with ICI or with chemotherapy, respectively. Real-world OS, derived from insurance claims data, was calculated from the time of CRC sample collection to the last contact. Hazard ratio (HR) was calculated using the Cox proportional hazards model, with p values calculated using the log-rank test. Results: The study cohort included 31,083 CRC cases (male: female = 1.2, age: 80% > = 50 years). Common molecular alterations included TP53 (73.6%), APC (77.6%), KRAS (47.4%), CTNNB1 (2.0%), and HER2 amplification (1.7%). 1,503 patients were MSI-H (4.83%), 21,330 as MSS (68.6%), and 8,250 indeterminate. MSI-H patients receiving concurrent ICI/metformin had similar OS (52.7 vs. 55.4 months, HR = 0.78, 95% CI: 0.41 – 1.51, p = 0.462). Conversely, OS was increased in MSS patients on concomitant chemotherapy and metformin (38.1 vs 31.1 months, HR = 0.77, 95% CI: 0.69 – 0.86, p < 0.00001). In comparing real-world OS between left-sided and right-sided colorectal cancer (CRC), regardless of metformin use, multivariate analysis incorporating molecular alterations revealed longer OS for left-sided MSS CRC compared to right-sided (HR = 0.80, 95% CI: 0.76 – 0.84, p < 0.00001). However, further improvement in OS was associated with concurrent metformin use in both right-sided and left-sided tumors. Conclusions: In this retrospective analysis of real-world clinical outcomes, patients receiving concomitant metformin and cytotoxic chemotherapy had improved clinical outcomes in MSS CRC compared to those not on concurrent metformin. However, the concurrent use of metformin with ICIs in MSI-H CRC did not show an impact on clinical outcomes given low sample size. These results add to the existing body of literature on the potential benefits of metformin in the context of MSS CRC and underscore the importance of a prospective controlled study of concurrent metformin use with systemic chemotherapy in metastatic CRC. Limitations of this study involves the potential inclusion of cases with prior metformin use, small sample size, retrospective analyses, and the lack of control for the patients with type II DM.

128P Real-world survival outcomes in MSS colorectal cancer(CRC) patients based on mesothelin(MSLN) expression

128P Real-world survival outcomes in MSS colorectal cancer(CRC) patients based on mesothelin(MSLN) expression

51P Phase II dose expansion study of DSP107, a first-in-class fusion protein targeting CD47 and 4-1BB, in combination with atezolizumab in patients with advanced MSS colorectal cancer

51P Phase II dose expansion study of DSP107, a first-in-class fusion protein targeting CD47 and 4-1BB, in combination with atezolizumab in patients with advanced MSS colorectal cancer

Prognosis and immunotherapy efficacy in dMMR&MSS colorectal cancer patients and an MSI status predicting model.

The inconsistency between mismatch repair (MMR) protein immunohistochemistry (IHC) and microsatellite instability PCR (MSI-PCR) methods has been widely reported. We aim to investigate the prognosis and the effect of immunotherapy in dMMR by IHC but MSS by MSI-PCR (dMMR&MSS) colorectal cancer (CRC) patients. A microsatellite instability (MSI) predicting model was established to help find dMMR&MSS patients. MMR and MSI states were detected by the IHC and MSI-PCR in 1622 CRC patients (ZS6Y-1 cohort). Logistic regression analysis was used to screen clinical features to construct an MSI-predicting nomogram. We propose a new nomogram-based assay to find patients with dMMR&MSS, in which the MSI-PCR assay only detects dMMR patients with MSS predictive results. We applied the new strategy to a random cohort of 248 CRC patients (ZS6Y-2 cohort). The consistency of MMR IHC and MSI-PCR in the ZS6Y-1 cohort was 95.7% (1553/1622). Both pMMR&MSS and dMMR&MSS groups experienced significantly shorter overall survival (OS) than those in dMMR by IHC and MSI-H by MSI-PCR (dMMR&MSI-H) group (hazard ratio [HR] = 2.429, 95% confidence interval [CI]: 1.89-3.116, p < .01; HR = 21.96, 95% CI: 7.24-66.61, p < .01). The dMMR&MSS group experienced shorter OS than the pMMR&MSS group, but the difference did not reach significance (log rank test, p = .0686). In the immunotherapy group, the progression-free survival of dMMR&MSS patients was significantly shorter than that of dMMR&MSI-H patients (HR = 13.83, 95% CI: 1.508-126.8, p < .05). The ZS6Y-MSI-Pre nomogram (C-index = 0.816, 95% CI: 0.792-0.841, already online) found 66% (2/3) dMMR&MSS patients in the ZS6Y-2 cohort. There are significant differences in OS and immunotherapy effect between dMMR&MSI-H and dMMR&MSS patients. Our prediction model provides an economical way to screen dMMR&MSS patients.

Abstract CT033: Avelumab combined with regorafenib in solid tumors with tertiary lymphoid structures: A phase 2 REGOMUNE trial cohort

Abstract Background: Mature tertiary lymphoid structures (mTLS) predict improved outcome in patients treated with immune checkpoint inhibitors (ICIs). However, a significant proportion of patients with TLS-positive tumors do not respond to ICI when used as a single agent and may therefore benefit from combination therapy. The multikinase inhibitor, regorafenib, deplete regulatory T cells, an immune population associated with resistance to ICI in TLS-positive tumors. We report the results of the PD-L1 inhibitor avelumab combined with regorafenib in patients with mTLS-positive advanced solid tumors. Methods: ‘Regomune’ is an open-label, multicenter phase II study assessing the combination of avelumab (10mg/kg IV every 14 days) with regorafenib (160 mg daily for 3 weeks in a 4-week cycle) in patients with advanced mTLS-positive solid tumors. The mTLS status was centrally assessed as previously described (Vanhersecke et al Nature Cancer 2021). All patients had confirmed progressive disease at inclusion, based on a central review of imaging. The primary efficacy endpoint was a 6-month non-progression rate using RECIST v1.1 based on blinded central review. 29 assessable patients were deemed necessary, and to meet the primary endpoint, at least 8 patients needed to be progression-free at 6 months. Results: Between January 2021 and July 2022, 132 patients (5 centers) underwent mTLS screening. Of these, 55 (41.7%) were identified as mTLS+, and 38 were included in the study. The top five histological subtypes were MSS colorectal cancer (15.8%), sarcoma (13.1%), oesogastric (10.5%), biliary tract (7.9%), and pancreatic cancer (7.9%). The most frequent grade 3/4 adverse events were palmar-plantar erythrodysesthesia syndrome (23.7%), maculo-papular rash (18.4%), fatigue, and oral mucositis (7.9% each). No treatment-related deaths were reported. Of the 34 patients assessed for efficacy, 16 (47%) showed tumor shrinkage, with 9 achieving a partial response (26.7%) and 7 having stable disease (20.6%). The median duration of response was 6 months. Twelve patients (comprising various tumor types including MSS colorectal cancer, small bowel carcinomas, biliary tract cancer, sarcomas, thyroid and gynecological tumors.) were progression-free at 6 months, marking the study’s primary endpoint achievement. The median progression-free survival and overall survival were 3.6 months and 8.6 months, respectively. Spatial transcriptomics, multiplex immunofluorescence (IF) of tumor tissues, and comprehensive plasma proteomics analysis have collectively uncovered critical biomarkers that significantly determine both sensitivity and resistance to treatment. Conclusions: This is the first histology-agnostic clinical trial employing mTLS as a biomarker for patient selection for treatment with an immune checkpoint inhibitor-based regimen. Durable responses were recorded, even in cases typically resistant to immunotherapy, confirming the predictive value of mTLS. Trial Registration NCT03475953 Citation Format: Antoine Italiano, Sophie Cousin, Carine Bellera, Jean-Philippe Guegan, Jean-Philippe Metges, Antoine Adenis, Rastilav Bahleda, Philippe Cassier, Coralie Cantarel, Michele Kind, Jean Palussiere, Lucile Vanhersecke, Alban Bessede. Avelumab combined with regorafenib in solid tumors with tertiary lymphoid structures: A phase 2 REGOMUNE trial cohort [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT033.

Abstract 314: Fixative eXchange (FX)-seq reveals single nucleus transcriptional landscapes of archived clinical cancer FFPE specimens

Abstract The wide availability of FFPE tissues stored in hospitals and biobanks could potentially be an invaluable resource to gain insights for improved medical treatment towards precision medicine by combining genomic and transcriptomic data with pathological annotations and medical records. Nevertheless, the majority of current single-cell sequencing methods depend on fresh or fresh-frozen samples to generate high-quality transcriptome data due to the limited reverse transcription (RT) yields in FFPE samples. Consequently, single-cell level transcriptomic studies of FFPE samples have been a longstanding challenge. Here, we present Fixative-eXchange (FX)-seq, a highly scalable snRNA-seq method for heavily paraformaldehyde (PFA)-fixed and/or FFPE samples. We successfully analyzed a total of nearly 320k nuclei from various samples, including PFA-fixed tissue, FFPE blocks, FFPE and hematoxylin and eosin (H&amp;E)-stained sections from mouse brain and human clinical cancer specimens. In a human gastrointestinal stromal tumor (GIST) FFPE sample, we observed rare transcriptomic transitions toward increased epigenetic modifications affected by acquired resistance in response to prolonged imatinib treatment. Furthermore, in an archived human colorectal cancer (CRC) FFPE sample, spatially-contextualized FX-seq with pathologist annotation distinguishes tumor cells from epithelial progenitors along with identification of the tumor microenvironment (TME) such as cancer-associated fibroblasts (CAFs). We then proceeded to investigate transcriptional programs associated with drug resistance and lack of response in immunotherapy observed in CRC patients. With a hypothesis-driven curation, we compared transcription profiles at the single-nucleus level observed in MSS and MSI-H CRC patients from archived FFPE blocks and found distinctive transcriptional profiles from each group. Overall, FX-seq holds promise for clinical research, precision medicine, biomarker discovery, and molecular diagnosis using archived clinical FFPE specimens. Citation Format: Han-Eol Park, Yu Tak Lee, Jaewon Lee, Junsuk Lee, Hyelin Ji, Young-Lan Song, Yoon Dae Han, Hyunki Kim, Chang Ho Sohn. Fixative eXchange (FX)-seq reveals single nucleus transcriptional landscapes of archived clinical cancer FFPE specimens [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 314.

Abstract 1040: Development of a novel RNA-based microsatellite stable predictive response signature (MSS-PRS) to identify MSS colorectal cancer (CRC) patients with a microsatellite instability-high (MSI-H) molecular phenotype

Abstract Introduction: MSI-H and mismatch repair deficient (dMMR) tumors are associated with favorable immune checkpoint inhibitor (ICI) responses (PMID: 3326454). However, up to 95% of CRC tumors are MSS/proficient MMR (pMMR) leading to poorer prognosis and treatment outcomes than MSI-H/dMMR patients (PMID: 12867608, 26028255). In MSS/pMMR metastatic CRC, multiple combination therapies are being investigated despite a lack of biomarkers to guide therapy. Therefore, we developed an RNA-based MSS-PRS with a primary objective to identify MSS tumors that have MSI-H/dMMR molecular features indicative of ICI response. Experimental Procedures: The MSS-PRS was developed using the TCGA CRC cohort (COAD; n=268). Training labels were assigned using the MSI Mantis score and mutation status from 8 genes with reported MSI association. Samples called “activated” had both a gene mutation and an MSI Mantis score &amp;gt; 0.4 (i.e., MSI-H), and samples called “non-activated” were wild type for all genes and had MSI Mantis score &amp;lt; 0.4. All other samples were designated “ambiguous” and excluded from training. Two thirds of the non-ambiguous samples were assigned to the classifier training set and all remaining samples were assigned to the test set. Using ClaNC software (PMID: 16269418) and cross-validation in the training set, a nearest centroid classifier was developed from a set of high mean, high variance candidate genes to select an optimal gene set to separate activated and non-activated groups. The classifier performance was evaluated in the test set. Results: The MSS-PRS contained 112-genes enriched for mismatched DNA binding, DNA damage repair, PD-L1, innate and adaptive immune response, cellular immunity, and cytokines. In the test set, the classifier called 44 of 46 MSI-H samples activated; of the remaining 77 samples that were MSS tumors, 38 were called activated and 39 were called not activated. Visual inspection of heat maps of tumor by MSI/MSS-PRS status and their association with TMB and CRC-related mutations suggest greater differences between MSS tumors called activated and MSI-H tumors than between MSS tumors called activated and MSS tumors called not activated. In contrast, immune marker expression profiles in MSS tumors called activated were markedly more similar to MSI-H tumors compared to MSS tumors called non-activated. Summary and Conclusions: Herein we described the development of a novel MSS-PRS that captures an MSI-H/dMMR-like molecular phenotype in a subset of patients with MSS tumors despite their lack of high TMB or overt MSI defects. Based upon these initial findings, further development of the MSS-PRS and its clinical validation as a tool to select patients with MSS tumors who may benefit from ICI-containing treatment regimens is warranted. Citation Format: Kirk Pappan, Gregory Mayhew, Jonathan Shepherd, Yuelong Guo, Kirk Beebe, Joel Eisner, Michael Milburn. Development of a novel RNA-based microsatellite stable predictive response signature (MSS-PRS) to identify MSS colorectal cancer (CRC) patients with a microsatellite instability-high (MSI-H) molecular phenotype [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1040.

Updates on immunotherapy of gastrointestinal cancers and practical challenges

Gastrointestinal (GI) cancers are the most common tumors of the digestive system, and their high morbidity and cancer-related mortality dramatically threaten the health of the population. With the researching progress of immunotherapy, its use in the treatment of GI cancers in the perioperative and advanced stages is becoming more and more important. Currently, immunotherapy has become the standard first-line treatment for MSI-H late-stage colorectal cancer, while in the first-line treatment of late-stage gastric cancer, immunotherapy combined with chemotherapy and HER2-targeted drugs (in HER2-positive patients) has also achieved significant efficacy and long-term survival benefits. Advances in immunotherapy in the neoadjuvant and adjuvant treatment and in the second- and later-line treatment of late-stage GI cancers have demonstrated its promising therapeutic potential. However, there is still an urgent need for future studies to explore more immunotherapy combination strategies for patients with GI cancers, especially with MSS colorectal cancers.

Molecular and clinical characteristics of POLE/POLD1 alterations among patients with colorectal cancer.

184 Background: POLE and POLD1 alterations (DNA polymerase ε and DNA polymerase δ) are key biomarkers of immune response for patients with MSS colorectal cancers (CRC). The clinical and molecular characteristics of POLE/POLD1 alterations are not yet well defined across CRCs. In this study, we investigated the clinical/molecular features of POLE and POLD1 alterations and its association with MSI-H CRC. Methods: All the patients and mutation data were selected from the cBioPortal database (https://www.cbioportal.org). All nonsynonymous mutations including missense, frameshift, nonsense, nonstop, splice site, and translation start site changes of POLE/POLD1 were considered. 21 studies were used in the analysis. 7179 data samples were obtained from 7179 patients. Tumors included were from all stages of CRCs. POLE/POLD1 mutations were from mutation tables, only protein-changing mutations were kept. MSI-H status was based on mutation data (presence of MLH1/PMS2/MSH2/MSH6 mutations). Results: Of 7179 patients with all stage CRCs, 6.1% (439) were found to harbor mutated POLE/POLD1 genes. Among those, 3446 patients had known MSI status and 14.9% (514/3446) had MSI-H disease. Notably, 3.3% patients with POLE/POLD1 mutations were found to have concurrent MSI-H disease (co-existence) and only 1.1% of patients with POLE/POLD1 mutations had MSS CRC. MSI status was unknown for 1.7% of patients with POLE/POLD mutant CRC. The mean age for patients with POLE/POLD1 + with or without MSI-H disease was 67. POLE/POLD mutations were exceedingly more common in colon than rectum regardless of MSI-H status (85% vs 15% overall and 88% vs 12% in MSI-H subgroup). No difference was seen among genders for the distribution of POLE/POLD1 mutations. Conclusions: POLE/POLD1 mutations frequently co-exist with MSI-H disease in CRC. Patients with MSS-CRC harboring POLE/POLD1 mutations represent a smaller subgroup of CRC (~1%). The incidence of POLE/POLD1 somatic mutations was more common among patients with colon cancer than those with rectal cancer.

Combining low-dose regorafenib with pembrolizumab for patients with MSI-H colorectal cancer: REGPEM-CRC-01.

TPS238 Background: Treatment for microsatellite instability-high (MSI-H)/mismatch repair deficient (MMR-D) colorectal cancer (CRC) has rapidly evolved in the last decade. The KEYNOTE 177 trial recently established pembrolizumab as a frontline therapy for patients with MSI-H CRC. However, in this study, approximately 40% of patients were noted to have disease progression within 6 months of treatment. Furthermore, an additional 10% of patients experienced acquired resistance to therapy. Therefore, there is an unmet need to improve outcomes for patients with MSI-H CRC. Preclinical studies have shown vascular endothelial growth factor (VEGF) signaling to be overactive in MSI-H compared to MSS CRC (Hansen et al. Colorectal Dis. 2011). Moreover, exploratory analysis of CALBG-80405 and PARADIGM trials showed that patients with MSI-H CRC were more likely to benefit from anti-VEGF therapy than those with MSS disease. Regorafenib, an FDA-approved agent for patients with mCRC, is a potent VEGF inhibitor with immune modulatory effects on the tumor microenvironment. We hypothesize that adding low-dose regorafenib to pembrolizumab as frontline therapy may create synergistic activity in addition to the known clinical activity of each agent in MSI-H CRC. Methods: In the lead-in arm of this prospective study, 22 patients will be enrolled. Patients will receive regorafenib 60 mg daily on days 1–14 (2 weeks on) followed by 7 days off (1 week off) in combination with pembrolizumab 200 mg in the cycle 1. In the following cycles, patients will receive regorafenib 90 mg daily for 2 weeks on 1 week off in combination with pembrolizumab 200 mg every 3 weeks. The primary outcome for the lead-in arm is overall response rate (ORR) within 12 months of treatment by RECIST 1.1. criteria. A formal one-sided hypothesis test will be conducted for futility, assuming that we will reject the null hypothesis of a target ORR only if we have strong evidence. In this study, we assume a null hypothesis that ORR is 0.60, which would reflect significant clinical improvement over the current standard of ORR = 0.43 from KEYNOTE 177. The alternative hypothesis is that ORR is less than 0.60. For the lead-in phase of the study, the emphasis is on controlling Type I error to be small, approximately 0.05. In the randomized phase of the study, patients will receive pembrolizumab monotherapy or pembrolizumab in combination with regorafenib 90 mg. The sample size for the randomized phase of trial was determined based on an assumed median of PFS of 28 months with pembrolizumab and regorafenib combination (investigational arm). The standard of care pembrolizumab monotherapy results in a median PFS of 16 months when given as a first-line therapy. We hypothesize the proposed treatment will increase median PFS to 28 months from 16 months (N=132; H0: 16 months vs., H1: 28 months; Type I error: 0.05, power 80%). Clinical trial information: NCT06006923 .

Abstract C124: Assessment of the anticancer potential of a natural compound euphol in colorectal cancer from in vitro and in vivo mouse models

Abstract Introduction and objectives: Euphol, a tetracyclic triterpene alcohol, is the main component in the sap of the Euphorbiaceae family of plants in subtropical and tropical regions. It has been reported as a modulator of protein kinases C (PKC) activity and to possess several properties, including anti-inflammatory and, more recently, antineoplastic action. These findings further amplified the therapeutic interest in euphol for cancer prevention and treatment. In the present study, we aimed to explore the in vitro and in vivo antitumor effect of synthetic euphol on colorectal cancer (CRC) to provide insight into euphol-based therapies for cancer patients. Methods: Cytotoxicity potential of commercial synthetic euphol on CRC cell lines (HCT15, LOVO – MSI) and (SW620, HT29 – MSS) and mouse organoids derived from ApcLoxP/+-Cdx2 mice was analyzed by MTS-based viability assay using CellTiterGlo kit. The clonogenic potential of CRC cell lines was assessed following a 10-day treatment with different doses of euphol. Quantitative RT-PCR and Western blot analyses were performed to study the effects of euphol on the gene and protein expression of the PKCs isoforms in CRC cell lines and organoids. In addition, a PDX mouse model was established using a surgical sample from a CRC patient. For in vivo studies, the PDX model and ApcLoxP/+-Cdx2 mice were administered euphol or vehicle by mouth for 10 days to assess the therapeutic effect and 8 weeks to assess the preventive effect, respectively. Results: Treatment with euphol resulted in reduced cell viability in both MSS and MSI CRC cell lines, and mouse organoids, following a 72-hour exposure. Euphol also promoted the reduction of the clonogenic potential of CRC cell lines in a dose-dependent manner. Further, the PKCα, PKCβ, PKCδ, and PKCZ gene and protein expression were stimulated in euphol-treated organoids, compared to control. Notably, we observed a significant decrease in tumor volume and suppressed tumor growth after 10 days of treatment with euphol in a PDX mouse model. Euphol-treated ApcLoxP/+-Cdx2 mice for 8 weeks also showed reduced colonic polyposis compared to untreated mice. Conclusions: These results indicate that synthetic euphol has a cytotoxic potential in inhibiting cell proliferation of CRC cells in both 2D and 3D models, and in vivo models through modulation of the expression of genes involved PKC pathway, thus highlighting the therapeutic potential of euphol for CRC. Citation Format: Ana Laura Vieira Alves, Ana Carolina Martin, Krishna M Sinha, Viviane Aline Oliveira Silva, Renato José da Silva-Oliveira, Silvia A Teixeira, Denise P Guimaraes, Luis Gustavo Romagnolo, Monise Tadin Reis, Fahriye Duzagac, Eduardo Vilar, Rui Manuel Reis. Assessment of the anticancer potential of a natural compound euphol in colorectal cancer from in vitro and in vivo mouse models [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr C124.

Application of sintilimab combined with anlotinib hydrochloride in the clinical treatment of microsatellite stable colorectal cancer

BACKGROUND Microsatellite stable (MSS) colorectal cancer (CRC) is a common type of tumor with limited treatment options. Sintilimab and anlotinib hydrochloride are two extensively studied anticancer drugs. AIM To probe the clinical value of combining sintilimab with anlotinib hydrochloride in MSS CRC treatment. METHODS During the period spanning from April 2019 to April 2022, Zhejiang Provincial People’s Hospital accommodated a cohort of 92 patients diagnosed with MSS CRC who were classified into two distinct groups in our study, the observation group and the control group. The control group was administered anlotinib hydrochloride as their designated therapy, whereas the observation group received the additional treatment of sintilimab in conjunction with the therapy assigned to the control group. The administration of treatment occurred in cycles consisting of a duration of 3 wk, and the evaluation of effectiveness took place subsequent to the completion of two consecutive cycles of treatment within both groups. A comparative analysis between the two groups was conducted to assess the short-term efficacy and ascertain the incidence of adverse events transpiring throughout the duration of the treatment period. Changes in the levels of carcinoembryonic antigen, carbohydrate antigen 199 (CA199), CA125, and T cell subsets (CD4+, CD8+, CD4+/CD8+) as well as the assessment of the quality of life using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30 were compared between the two groups prior to and subsequent to therapy. Finally, a 1-year follow-up was conducted for both groups of patients, and the survival status was recorded and analyzed. RESULTS The short-term effectiveness displayed by the observation group surpassed that exhibited by the control group, with a statistically significant discrepancy (76.09% vs 50.00%), reaching a significance level denoted as P &lt; 0.05. Following the administration of treatment, the observation group manifested a considerable reduction in numerous serum indicators, which were found to be lower than the corresponding pretreatment levels within the same group as well as the post-treatment levels observed in the control group (P &lt; 0.05). Post-treatment, the T lymphocyte subset levels within the observation group demonstrated a remarkable amelioration, surpassing the corresponding pre-treatment levels observed within the same group as well as the post-treatment levels observed in the control group (P &lt; 0.05). Subsequent to the therapeutic intervention, the observation group showcased a notable amelioration in the scores associated with multiple dimensions of life quality. These scores outperformed the pretreatment scores within the same group as well as the post-treatment scores observed in the control group (P &lt; 0.05). The safety levels of drug use in the two group were comparable (19.57% vs 13.04%), and no distinct difference was observed upon comparison (P &gt; 0.05). After the completion of treatment, both groups of patients underwent a 1-year follow-up outside the hospital. Throughout this period, 1 patient within the observation group and 2 patients within the control group became untraceable and were lost to follow-up. During the follow-up period of the observation group, 12 patients died, resulting in a survival rate of 73.33% (33/45), while in the control group, 21 patients died, resulting in a survival rate of 52.27% (23/44). The implementation of Kaplan-Meier survival analysis revealed a conspicuous contrast in survival rates exhibited by the two groups (log-rank = 4.710, P = 0.030). CONCLUSION The combination of sintilimab and anlotinib hydrochloride demonstrated favorable efficacy in the treatment of MSS CRC patients, leading to improvements in patient immunity and prognosis. Additionally, it exerted inhibitory effects on the expression of carcinoembryonic antigen, CA199, and CA125.

Immunotherapy response in microsatellite stable metastatic colorectal cancer is influenced by site of metastases

BackgroundPrior studies indicate that colorectal cancer patients with liver metastases did not benefit from regorafenib, nivolumab (REGONIVO) or regorafenib, ipilimumab, nivolumab (RIN) treatments, while those without liver metastases showed significant response. This study explores the impact of metastatic sites on treatment outcomes. MethodsChemotherapy-refractory colorectal cancer patients treated with REGONIVO or RIN were evaluated, focusing on 2-month organ-specific response, ORR, PFS and OS based on metastatic sites. ResultsOf the 96 patients analyzed (58 REGONIVO, 38 RIN), liver or peritoneal metastases led to poor outcomes, with 0 % ORR, and median PFS of 2.0 and 1.5 months respectively. In contrast, lung-only metastases had an ORR of 56.3 % and a PFS of 14 months. The presence of concurrent LN or other extrahepatic metastatic disease in patients with lung metastatic disease diminished but did not prohibit responses. The 2-month response assessment revealed activity in the lungs, soft tissues, and distant lymph nodes. ConclusionsREGONIVO and RIN were most active in lung-only metastases. Liver and peritoneal metastases were resistant. Future checkpoint inhibitor trials in MSS colorectal cancer should stratify patients based on metastatic locations.

Peritumoral Immune-suppressive Mechanisms Impede Intratumoral Lymphocyte Infiltration into Colorectal Cancer Liver versus Lung Metastases.

Our results demonstrate that functional status and spatial distribution of immune cells vary significantly across different metastatic sites in MSS colorectal cancer. These findings suggest that metastatic site-dependent immune contexture may underlie discordant responses to ICI therapy in patients with MSS colorectal cancer.

Neoantigen Cancer Vaccine for Immunologically Cold Microsatellite-stable Colorectal Cancer

Immunotherapies, such as immune checkpoint inhibitors (ICIs), have revolutionized management of some cancers but have little benefit for microsatellite-stable colorectal cancer patients (MSS-CRC). This is, in part, due to the low mutations and neoantigen expression in this immunogenically "cold" MSS-CRC. Therefore, we aim to develop novel shared neoantigen-based therapeutic cancer vaccine to reinvigorate antitumor immunity and enhance the therapeutic benefit of radiotherapy in MSS-CRC. To identify novel highly expressed and shared neoantigens, we collected 40 match-paired adjacent normal and tumor tissues from MSS-CRC patients for WES-seq, RNA-seq, and liquid chromatography-MS/MS (LC-MS/MS). By incorporating these databases, we established Neoantigen Discovery and Validation (NeoDiva) system to identify a cluster of highly expressed and shared neoantigens derived from non-coding regions and evaluate its immunogenicity by HLA-A*11 transgenic mice. We then develop a neoantigen-based therapeutic cancer vaccine by an engineered adenovirus-associated virus (AAV) to evaluate its therapeutic efficacy in combination with radiotherapy in MSS-CRC animal model. We identified a cluster of highly expressed and shared neoantigens (HLA-A*11-restricted) derived from non-coding regions. The immunogenicity of these novel neoantigens was demonstrated by HLA-A*11 transgenic mice and ex vivo stimulation. Moreover, the engineered AAV-based neoantigen cancer vaccine significantly eradicates cancer cells, prevents distant metastasis, prolong survival period in combination with radiotherapy. By flow cytometry, ELISPOT and MHC-I-tetramer assay, we demonstrated the recruitment of tumor-infiltrating lymphocytes was remarkably increased and neoantigen-specific T cell response was enhanced. Moreover, these isolated neoantigen-specific T cells can recognize cancer cells and produce IFNg to kill cancer cells. Neoantigens identified by our NeoDiVa platform, via the combination of radiotherapy and a novel AAV vaccine delivery system, boosted antigen-specific T-cell function and improve tumor control of limnologically "cold" MSS colorectal cancer in vivo. We are in the process of obtaining an IND and initiating Phase I/II clinical trial to validate safety and efficacy of these exciting findings.

Preliminary exploration of the effects of environmental factors on the microsatellite status of BRAF-mutated colorectal cancer

BackgroundTo investigate the expression of EBV products and frequency of gallstone disease (GD) among different microsatellite status in colorectal cancer (CRC) with BRAFV600E mutation.MethodsWe collected 30 CRC patients with BRAFV600E mutation and 10 BRAF ( −) CRC patients as well as 54 healthy subjects. Tumor tissue samples were collected to detect the mutation of BRAF, KRAS, and TP53. Microsatellite status was determined by immunohistochemistry and PCR. EBER in situ hybridization was performed to detect EBV. In addition, we also collected clinical information about the patients.ResultsWe found that although EBV products were detected in CRC, there were no significant differences in the EBV distribution between the different BRAF groups. Our study demonstrated that BRAFV600E mutation and BRAFV600E with MSI were significantly more frequent in the right CRC. Furthermore, the KRAS mutation rate in the BRAF-wild-type group was proved to be significantly higher than that in the BRAF mutation group. In addition, we revealed that BRAF mutation and MSI were independent risk factors of TNM stage. The frequency of GD was higher in CRC patients than in general population, and although there was no significant difference between CRC with or without BRAFV600E mutation, the highest frequency of GD was found in MSS CRC with BRAFV600E mutation.ConclusionsEBV plays a role in CRC, but is not a determinant of different microsatellite status in CRC with BRAFV600E mutation. The frequency of GD in MSS CRC with BRAFV600E mutation is significantly higher than that in the general population.

ASCL2 induces an immune excluded microenvironment by activating cancer-associated fibroblasts in microsatellite stable colorectal cancer

Proficient mismatch repair or microsatellite stable (pMMR/MSS) colorectal cancers (CRCs) are vastly outnumbered by deficient mismatch repair or microsatellite instability-high (dMMR/MSI-H) tumors and lack a response to immune checkpoint inhibitors (ICIs). In this study, we reported two distinct expression patterns of ASCL2 in pMMR/MSS and dMMR/MSI-H CRCs. ASCL2 is overexpressed in pMMR/MSS CRCs and maintains a stemness phenotype, accompanied by a lower density of tumor-infiltrating lymphocytes (TILs) than those in dMMR/MSI CRCs. In addition, coadministration of anti-PD-L1 antibodies facilitated T cell infiltration and provoked strong antitumor immunity and tumor regression in the MC38/shASCL2 mouse CRC model. Furthermore, overexpression of ASCL2 was associated with increased TGFB levels, which stimulate local Cancer-associated fibroblasts (CAFs) activation, inducing an immune-excluded microenvironment. Consistently, mice with deletion of Ascl2 specifically in the intestine (Villin-Cre+, Ascl2flox/flox, named Ascl2 CKO) revealed fewer activated CAFs and higher proportions of infiltrating CD8+ T cells; We further intercrossed Ascl2 CKO with ApcMin/+ model suggesting that Ascl2-deficient expression in intestinal represented an immune infiltrating environment associated with a good prognosis. Together, our findings indicated ASCL2 induces an immune excluded microenvironment by activating CAFs through transcriptionally activating TGFB, and targeting ASCL2 combined with ICIs could present a therapeutic opportunity for MSS CRCs.

Identification of a Twelve-microRNA Signature with Prognostic Value in Stage II Microsatellite Stable Colon Cancer.

We aimed to identify and validate a set of miRNAs that could serve as a prognostic signature useful to determine the recurrence risk for patients with COAD. Small RNAs from tumors of 100 stage II, untreated, MSS colon cancer patients were sequenced for the discovery step. For this purpose, we built an miRNA score using an elastic net Cox regression model based on the disease-free survival status. Patients were grouped into high or low recurrence risk categories based on the median value of the score. We then validated these results in an independent sample of stage II microsatellite stable tumor tissues, with a hazard ratio of 3.24, (CI95% = 1.05-10.0) and a 10-year area under the receiver operating characteristic curve of 0.67. Functional analysis of the miRNAs present in the signature identified key pathways in cancer progression. In conclusion, the proposed signature of 12 miRNAs can contribute to improving the prediction of disease relapse in patients with stage II MSS colorectal cancer, and might be useful in deciding which patients may benefit from adjuvant chemotherapy.