68Ga-FAPI PET imaging monitors response to combined TGF-βR inhibition and immunotherapy in metastatic colorectal cancer

To date, anticancer immunotherapy has presented some clinical benefits to most of advanced mismatch repair deficient (dMMR)/microsatellite instability-high (MSI-H) colorectal cancer (CRC) patients. In addition to MSI status, we aimed to reveal the potential predictive value of adenomatous polyposis coli (APC) gene mutations in CRC patients. A total of 238 Chinese CRC patients was retrospectively identified and analyzed for clinical features and gene alternations in APC-mutant type (MT) and APC-wild-type (WT) groups. Clinical responses were then evaluated from the public TCGA database and MSKCC immunotherapy database. Although programmed cell death ligand 1 (PD-L1) level, MSI status, loss of heterogeneity at the human leukocyte antigen (HLA LOH), and tumor neoantigen burden (TNB) level were not statistically different between the APC-MT group and APC-WT group, tumor mutation burden (TMB) level was significantly higher in APC-MT patients (P < 0.05). Furthermore, comutation analysis for APC mutations revealed co-occurring genomic alterations of PCDHB7 and exclusive mutations of CTNNB1, BRAF, AFF3, and SNX25 (P < 0.05). Besides, overall survival from MSKCC-CRC cohort was longer in the APC-WT group than in the APC-MT group (HR 2.26 (95% CI 1.05–4.88), P < 0.05). Furthermore, most of patients in the APC-WT group were detected as high-grade immune subtypes (C2–C4) comparing with those in the APC-MT group. In addition, the percentages of NK T cells, Treg cells, and fibroblasts cells were higher in APC-WT patients than in APC-MT patients (P < 0.05). In summary, APC mutations might be associated with poor outcomes for immunotherapy in CRC patients regardless of MSI status. This study suggested APC gene mutations might be a potential predictor for immunotherapy in CRC.

Phase I Clinical Trial of Autologous Ascites-derived Exosomes Combined With GM-CSF for Colorectal Cancer

Metastatic colorectal cancer (mCRC) is a heterogeneous disease. We reviewed the current clinical trials on immunotherapy in metastatic colorectal cancer with high microsatellite instability and microsatellite stability. Owing to the advances in immunotherapy, its use has gradually expanded from second- and third-line therapies to first-line, early neoadjuvant, and adjuvant therapies. Based on current research results, immunotherapy has shown very good results in dMMR/MSI-H patients, whether it is neoadjuvant therapy for operable patients or first-line or multi-line therapy for advanced patients. KEYNOTE 016 study also showed that patients with MSS were basically ineffective in single immunotherapy. Moreover, immunotherapy for colorectal cancer may also require identification of new biomarkers.

Potential role of the intratumoral microbiota in colorectal cancer immunotherapy

Introduction: Numerous studies have reported that tumor progression and invasiveness are determined not only by the malignant cancer cells themselves but also by the surrounding tumor microenvironment, including cancer-associated fibroblasts (CAFs). Although CAFs are implicated in tumor progression, their total depletion of CAFs has been demonstrated to induce more aggressive tumors, indicating that different CAF subpopulations have opposing tumor-promoting or tumor-inhibitory roles. Unfortunately, specific markers to target these subsets of CAFs are lacking. Expression of the immune checkpoint CD70 is normally tightly regulated and limited to cells of the lymphoid lineage only. Instead, tumors hijack CD70 to facilitate immune evasion by increasing the amount of suppressive regulatory T cells (Tregs), inducing T cell apoptosis and skewing T cells towards T cell exhaustion. Recently, a lot of clinical successes have been generated by the blockade of immune checkpoints. However, in colorectal cancer (CRC) the efficacy remains limited to a small subset of patients with mismatch repair-deficient (MSI) tumors which might be caused by the intense dialogue between stroma and malignant cells. Therefore, we have explored the expression patterns of the immune checkpoint molecule CD70 in CRC, with a particular focus on CAFs. Methods: The prognostic value of CD70 was analyzed by immunohistochemistry on 51 CRC specimens. In addition, the relationship with Tregs and microsatellite instability was explored. Furthermore, primary CAF cell lines were successfully cultured from 20 different primary resection specimens. These cell lines were used to study the effect of CD70 on the tumor microenvironment in vitro. Results: We revealed expression of CD70, not just on the malignant cells but on the majority of CAFs in invasive CRC specimens. Thereby, CD70-expression was significantly correlated with negative clinicopathological parameters such as metastasis (P=0.007), differentiation (P=0.053) and advanced stage (P=0.001). Moreover, CD70-positive CAFs proved to be a poor prognostic marker by univariate as well as multivariate analysis. We have also detected a significant association between elevated Treg amounts and CD70-expressing CAFs (P=0.012). In vitro data on the effects of CD70 on CRC behavior and immune escape are currently being analyzed. Conclusion: We have identified a new targetable CAF subpopulation, marked by the expression of CD70 and equipped with strong tumor-promoting properties. Thereby, we have found evidence of a potential cross talk between CD70+ CAFs and Treg, paving the way towards immune escape. The lack of association of CD70 expression and MSI-status, which highlights the potential of this target in CRC subsets that do not benefit from immune checkpoint blockade. We believe that targeting CD70 holds great potential in CRC, especially in light of the limited immunotherapeutic options available. Citation Format: Julie Jacobs, Vanessa Deschoolmeester, Karen Zwaenepoel, Christophe Hermans, Christian Rolfo, Marc Peeters, Filip Lardon, Vasiliki Siozopoulou, Evelien Smits, Patrick Pauwels. Blocking CD70+ cancer associated fibroblasts: Are we paving the way towards immunotherapy in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 958. doi:10.1158/1538-7445.AM2017-958

Background: TET1, a DNA demethylase, is encoded by TET1 gene. At present, TET1 mutation has been reported to be associated with enhanced tumor immunogenicity and activated anti-tumor immunity across multiple cancers. However, the clinical effect of TET1 mutation on immunotherapy in colorectal cancer is little known. Methods: 876 patients with colorectal cancer were enrolled in this study. Genomic profiling of DNA was performed on formalin-fixed paraffin-embedded tumor samples by NGS with 733 cancer-related genes panel. The somatic and germline mutation data were both obtained. Benign and likely benign mutations were excluded from our analysis. Programmed death ligand-1(PD-L1) expression status was determined by immunohistochemistry, evaluated with the combined positive score (CPS) and tumor proportion score (TPS). The efficiency of immunotherapy was analyzed in a cohort of 85 patients with colorectal cancer from Morris et al. Results: 40 of 876 patients (4.75%) harbored TET1 mutations, including nonsynonymous, frameshift and stopgain mutations. Totally, 66 TET1 single nucleotide mutation were identified. Median tumor mutation burden (TMB) value with TET1 mutations was 109.2 mutations/MB, significantly higher than 6.1 mutations/MB in TET1 wild-type group (p&amp;lt;0.001). Microsatellite instability-high (MSI-H) appeared more frequently in TET1 mutations group than TET1 wild-type group (50.0% vs 5.0%, p&amp;lt;0.001). For PD-L1 TPS, compare to TET1 wild type groups, the positive rate of PD-L1 expression in TET1 mutations was higher significantly (6.7% vs 2.7%, p&amp;lt;0.001). The same thing happened with PD-L1 CPS (50.0% vs 23.3%, p&amp;lt;0.001). Possibly, TET1 mutation was a potential marker for immunotherapy. The results were validated in a clinical cohort of immunotherapy, including 85 patients with colorectal cancer. The median overall survival was non-reached in 7 patients with TET1 mutations compare to 13 months in TET1 wild-type group (HR: 0.28, 95% CI 0.11-0.69, P=0.006). Conclusions: TET1 mutation was strongly associated with higher TMB, MSI-H and PD-L1 expression and improved OS in patients receiving immune checkpoint blockade treatment, suggesting that TET1 mutation is a novel predictive biomarker for immunotherapy in colorectal cancer. Citation Format: Shaojun Yu, Ding Zhang, Shiqing Chen. TET1 mutation as potential biomarker for immune checkpoint blockade in colorectal 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 347.

In contrast to other tumor types, immunotherapy has not yet become a relevant part of the treatment landscape of unselected colorectal cancer. Beside the small subgroup of deficient mismatch repair or microsatellite instable tumors (about 5%) as a surrogate for high mutational burden and subsequently high neoantigen load and immunogenicity, inhibitors of programmed death 1 (PD-1), programmed death ligand 1 (PD-L1) and/or cytotoxic T lymphocyte-associated antigen-4 were not or only modestly effective in metastatic colorectal cancer. Thus, a variety of combination approaches with chemotherapy, targeted therapy, toll-like receptor agonists, local ablation or oncolytic viruses is currently being evaluated in different disease settings. Despite several encouraging single arm data already presented or published, available randomized data are unimpressive. Adding PD-1/PD-L1 inhibitors to fluoropyrimidines and bevacizumab maintenance showed no beneficial impact on delaying progression. In refractory disease, the combination of PD-1/PD-L1 and MEK inhibitor was not different from regorafenib, whereas a PD-1/PD-L1 and cytotoxic T lymphocyte-associated antigen-4 inhibitor combination demonstrated better overall survival compared to supportive care alone. Clinical trials in all disease settings applying different combination approaches are ongoing and may define the role of immunotherapy in colorectal cancer.

A transformer-based pathomics model using endoscopic biopsy WSIs for predicting pathological complete response to preoperative immunotherapy in colorectal cancer.

&lt;div&gt;Abstract&lt;p&gt;Despite the fact that the local immunological microenvironment shapes the prognosis of colorectal cancer, immunotherapy has shown no benefit for the vast majority of colorectal cancer patients. A better understanding of the complex immunological interplay within the microenvironment is required. In this study, we utilized wet lab migration experiments and quantitative histological data of human colorectal cancer tissue samples (&lt;i&gt;n&lt;/i&gt; = 20) including tumor cells, lymphocytes, stroma, and necrosis to generate a multiagent spatial model. The resulting data accurately reflected a wide range of situations of successful and failed immune surveillance. Validation of simulated tissue outcomes on an independent set of human colorectal cancer specimens (&lt;i&gt;n&lt;/i&gt; = 37) revealed the model recapitulated the spatial layout typically found in human tumors. Stroma slowed down tumor growth in a lymphocyte-deprived environment but promoted immune escape in a lymphocyte-enriched environment. A subgroup of tumors with less stroma and high numbers of immune cells showed high rates of tumor control. These findings were validated using data from colorectal cancer patients (&lt;i&gt;n&lt;/i&gt; = 261). Low-density stroma and high lymphocyte levels showed increased overall survival (hazard ratio 0.322, &lt;i&gt;P&lt;/i&gt; = 0.0219) as compared with high stroma and high lymphocyte levels. To guide immunotherapy in colorectal cancer, simulation of immunotherapy in preestablished tumors showed that a complex landscape with optimal stroma permeabilization and immune cell activation is able to markedly increase therapy response &lt;i&gt;in silico&lt;/i&gt;. These results can help guide the rational design of complex therapeutic interventions, which target the colorectal cancer microenvironment. &lt;i&gt;Cancer Res; 77(22); 6442–52. ©2017 AACR&lt;/i&gt;.&lt;/p&gt;&lt;/div&gt;

&lt;div&gt;Abstract&lt;p&gt;Despite the fact that the local immunological microenvironment shapes the prognosis of colorectal cancer, immunotherapy has shown no benefit for the vast majority of colorectal cancer patients. A better understanding of the complex immunological interplay within the microenvironment is required. In this study, we utilized wet lab migration experiments and quantitative histological data of human colorectal cancer tissue samples (&lt;i&gt;n&lt;/i&gt; = 20) including tumor cells, lymphocytes, stroma, and necrosis to generate a multiagent spatial model. The resulting data accurately reflected a wide range of situations of successful and failed immune surveillance. Validation of simulated tissue outcomes on an independent set of human colorectal cancer specimens (&lt;i&gt;n&lt;/i&gt; = 37) revealed the model recapitulated the spatial layout typically found in human tumors. Stroma slowed down tumor growth in a lymphocyte-deprived environment but promoted immune escape in a lymphocyte-enriched environment. A subgroup of tumors with less stroma and high numbers of immune cells showed high rates of tumor control. These findings were validated using data from colorectal cancer patients (&lt;i&gt;n&lt;/i&gt; = 261). Low-density stroma and high lymphocyte levels showed increased overall survival (hazard ratio 0.322, &lt;i&gt;P&lt;/i&gt; = 0.0219) as compared with high stroma and high lymphocyte levels. To guide immunotherapy in colorectal cancer, simulation of immunotherapy in preestablished tumors showed that a complex landscape with optimal stroma permeabilization and immune cell activation is able to markedly increase therapy response &lt;i&gt;in silico&lt;/i&gt;. These results can help guide the rational design of complex therapeutic interventions, which target the colorectal cancer microenvironment. &lt;i&gt;Cancer Res; 77(22); 6442–52. ©2017 AACR&lt;/i&gt;.&lt;/p&gt;&lt;/div&gt;

Despite the fact that the local immunological microenvironment shapes the prognosis of colorectal cancer, immunotherapy has shown no benefit for the vast majority of colorectal cancer patients. A better understanding of the complex immunological interplay within the microenvironment is required. In this study, we utilized wet lab migration experiments and quantitative histological data of human colorectal cancer tissue samples (n = 20) including tumor cells, lymphocytes, stroma, and necrosis to generate a multiagent spatial model. The resulting data accurately reflected a wide range of situations of successful and failed immune surveillance. Validation of simulated tissue outcomes on an independent set of human colorectal cancer specimens (n = 37) revealed the model recapitulated the spatial layout typically found in human tumors. Stroma slowed down tumor growth in a lymphocyte-deprived environment but promoted immune escape in a lymphocyte-enriched environment. A subgroup of tumors with less stroma and high numbers of immune cells showed high rates of tumor control. These findings were validated using data from colorectal cancer patients (n = 261). Low-density stroma and high lymphocyte levels showed increased overall survival (hazard ratio 0.322, P = 0.0219) as compared with high stroma and high lymphocyte levels. To guide immunotherapy in colorectal cancer, simulation of immunotherapy in preestablished tumors showed that a complex landscape with optimal stroma permeabilization and immune cell activation is able to markedly increase therapy response in silico These results can help guide the rational design of complex therapeutic interventions, which target the colorectal cancer microenvironment. Cancer Res; 77(22); 6442-52. ©2017 AACR.

e14036 Background: CRC is the third most frequent cancer in men and second in women worldwide. Recently, immune checkpoint molecules such as PD-1/PD-L1 have been identified as a possible target for immunotherapy in CRC and are increasingly being tested in clinical trials in combination with chemotherapy. However, the role of PD-L1 expression in CRC tumor cells and its interaction with other clinicopathologic factors remains elusive. In this study, we evaluated the impact of neoadjuvant chemotherapy on the fraction of PD-L1 positive CETCs and to compare its expression to the primary tumor. Methods: CETCs were determined from the blood of 20 patients suffering from CRC in different stages of the disease. The number of CETCs and their expression of PD-L1 were investigated using the maintrac method. In parallel, PD-L1 expression and tumor infiltrating lymphocytes (TILs) were assessed by immunohistochemistry on tissue biopsies. Results: PD-L1 expression could be assessed in all patients with detectable CETCs with a median of 50%. CETCs were more frequently found to be PD-L1 positive than tissue, and no correlation was observed between tissue and CETCs PD-L1 expression. Interestingly, patients with neoadjuvant chemotherapy had more positive PD-L1 CETCs compared to patients without chemotherapy (mean 66,7 vs. 35,2 p &lt; 0.05), but the total number of CETCs was significantly lower in the neoadjuvant group. Also, patients with mucinous adenocarcinoma had more PD-L1 positive CETCs compared to other histological subtypes. The number of TILs was higher in patients with lymph node metastasis and larger tumors. TILs count did not differ in patients with and without neoadjuvant chemotherapy. Conclusions: Assessment of PD-L1 expression in CETCs is feasible, and CETCs are more often positive than in tissue. PD-L1 expression on CETCs was higher in patients who received neoadjuvant chemotherapy. Further studies are necessary to validate these findings.

There is increasing evidence in a range of cancer types that the microbiome plays a direct role in modulating the anti-cancer immune response both at the gut level and systemically. Differences in the gut microbiota have been shown to correlate with differences in immunotherapy responses in a range of non-gastrointestinal tract cancers. DNA mismatch repair-deficient (dMMR) colorectal cancer (CRC) is radically different to DNA mismatch repair-proficient (pMMR) CRC in clinical phenotype and in its very good responses to immunotherapy. While this has usually been thought to be due to the high mutational burden in dMMR CRC, the gut microbiome is radically different in dMMR and pMMR CRC in terms of both composition and diversity. It is probable that differences in the gut microbiota contribute to the varied responses to immunotherapy in dMMR versus pMMR CRC. Targeting the microbiome offers a way to boost the response and increase the selection of patients who might benefit from this therapy. This paper reviews the available literature on the role of the microbiome in the response to immunotherapy in dMMR and pMMR CRC, explores the potential causal relationship and discusses future directions for study in this exciting and rapidly changing field.

Immunotherapy focuses on selectively enhancing the host's immune response against malignant disease. It has been investigated as an important treatment modality against malignant disease for many years, but until recently its use was mostly limited to a few cancers. The advent of new immunemodulating agents in the recent past has changed the landscape for management of many solid tumors. Currently, immunotherapy offers a valuable, and in many cases, a more effective alternate to the conventional cytotoxic therapy. Colorectal cancer is a leading cause of cancer-related death. Despite progress in systemic therapy, most patients with metastatic colorectal cancer die of their disease. There is an unmet need for more effective treatments for patients with metastatic colorectal cancer. The current data support that colorectal tumors are immunoresponsive and a subset of patients with advanced disease achieve long term benefit with immunotherapy. This review aims to provide the current status of immunotherapy in patients with metastatic colorectal cancer. We researched sources published in the English language between January 2000 and August 2018 and listed within the PubMed database using combinations of the key words and reviewed the proceedings of international cancer conferences and current guidelines made by major cancer societies. In this review, we summarize the current status of research on immunotherapy in metastatic colorectal cancer and discuss various treatment modalities including checkpoint inhibitors, cancer vaccines, adoptive cell transfer, oncolytic virus therapy, and various other agents that are under investigation with a special emphasis on immune checkpoint inhibitors. Since the toxicity profile of immunotherapy is very different from conventional cytotoxic agents and could involve any organ system, we briefly review common adverse effects and their management.

Introduction: Encouraging clinical responses have been observed through various strategies designed to harness T-cells for their anti-tumor properties, including immune checkpoint inhibition, chimeric antigen receptor-expressing T-cells or bispecific molecules designed to co-engage T-cells and cancer cells. Furthermore, a positive correlation has been observed in colorectal cancer between the degree and type of T-cell infiltration and prognosis suggesting that T-cell recruitment strategies may be particularly advantageous in this type of cancer. We have developed MGD007, a Dual-Affinity Re-Targeting (DART®) protein designed to redirect T-cells to target gpA33 expressing colon cancer. MGD007 has enhanced pharmacokinetic properties via incorporation of a neonatal FcR-binding Fc domain. The gpA33 target was selected based on its ubiquitous expression in colorectal cancer including reactivity with putative cancer stem cell populations (Li 2013, AACR #3763). To enable preclinical toxicokinetics and dose optimization, MGD007 was designed to cross-react with non-human primates. Methods: MGD007 was stably expressed in CHO cells and purified to homogeneity via a standard antibody-purification platform; in vitro functional studies were performed with a range of colorectal cancer cell lines and primary human T-cells; tumor growth inhibition studies were performed in NOD-SCID mice co-implanted with Colo205 and human T-cells (1:1 E:T ratio) and treated IV with MGD007; pharmacokinetic analyses were performed in cynomolgus monkeys. Results: MGD007 displays the anticipated bispecific binding properties and mediates potent lysis of gpA33-positive - but not gpA33-negative cancer cell lines through recruitment of either human or cynomolgus monkey T-cells. Concomitant with CTL activity, both T-cell activation and expansion are observed in a gpA33-dependent manner. No cytokine activation was observed with human PBMC alone, consistent with the absence of gpA33 expression on peripheral blood cell populations. Both CD8 and CD4 T-cells mediated lysis of gpA33-expressing tumor cells, with activity accompanied by increases in granzyme levels. Xenograft studies showed tumor growth inhibition at doses as low as 4ug/kg. In cynomologus monkeys, 4 weekly doses of 200ug/kg were well tolerated, with prolonged PK consistent with that of an Fc-containing molecule. Conclusions: MGD007 displays potent activity against colorectal cancer cells consistent with a mechanism of action endowed in its design. Furthermore it displays favorable PK in cynomolgus monkeys supporting convenient dosing. Taken together, these data support further investigation of MGD007 as a potential novel therapeutic treatment for colorectal cancer. Citation Format: Paul A. Moore, Ralph Alderson, Kalpana Shah, Yinhua Yang, Steve Burke, Hua Li, Valentine Ciccarone, Ezio Bonvini, Syd Johnson. Development of MGD007, a gpA33 x CD3 bi-specific DART for T-cell immunotherapy of metastatic colorectal cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 669. doi:10.1158/1538-7445.AM2014-669