Effect of Combined Immune Checkpoint Inhibition vs Best Supportive Care Alone in Patients With Advanced Colorectal Cancer: The Canadian Cancer Trials Group CO.26 Study

A pilot trial of vaccination with Carcinoembryonic antigen and Her2/neu peptides in advanced colorectal cancer

Checkpoint-blockade therapy (CBT) is approved for select colorectal cancer (CRC) patents, but additional immunotherapeutic options are needed. We hypothesized that vaccination with carcinoembryonic antigen (CEA) and Her2/neu (Her2) peptides would be immunogenic and well tolerated by participants with advanced CRC. A pilot clinical trial (NCT00091286) was conducted in HLA-A2⁺ or -A3⁺ Stage IIIC-IV CRC patients. Participants were vaccinated weekly with CEA and Her2 peptides plus tetanus peptide and GM-CSF emulsified in Montanide ISA-51 adjuvant for 3 weeks. Adverse events (AEs) were recorded per NIH Common Terminology Criteria for Adverse Events version 3. Immunogenicity was evaluated by interferon-gamma ELISpot assay of in vitro sensitized peripheral blood mononuclear cells and lymphocytes from the sentinel immunized node. Eleven participants were enrolled and treated; one was retrospectively found to be ineligible due to HLA type. All 11 participants were included in AEs and survival analyses, and the 10 eligible participants were evaluated for immunogenicity. All participants reported AEs: 82% were Grade 1-2, most commonly fatigue or injection site reactions. Two participants (18%) experienced treatment-related dose-limiting Grade 3 AEs; both were self-limiting. Immune responses to Her2 or CEA peptides were detected in 70% of participants. Median overall survival (OS) was 16 months; among those enrolled with no evidence of disease (n = 3), median OS was not reached after 10 years of follow-up. These data demonstrate that vaccination with CEA or Her2 peptides is well tolerated and immunogenic. Further study is warranted to assess potential clinical benefits of vaccination in advanced CRC either alone or in combination with CBT.

Monoclonal Antibodies to CTLA-4 with Focus on Ipilimumab

The immune checkpoint cytotoxic T lymphocyte-associated antigen 4 (CTLA-4 or CD152) is a negative regulator of T-cell-mediated immune responses which plays a critical role in suppressing autoimmunity and maintaining immune homeostasis. Because of its inhibitory activity on T cells, CTLA-4 has been investigated as a drug target to induce immunostimulation, blocking the interaction with its ligands. The antitumor effects mediated by CTLA-4 blockade have been attributed to a sustained active immune response against cancer cells, due to the release of a brake on T cell activation. Ipilimumab (Yervoy, Bristol-Myers Squibb) is a fully human anti-CTLA-4 IgG1κ monoclonal antibody (mAb) that represents the first immune checkpoint inhibitor approved as monotherapy by FDA and EMA in 2011 for the treatment of unresectable/metastatic melanoma. In 2015, FDA also granted approval to ipilimumab monotherapy as adjuvant treatment of stage III melanoma to reduce the risk of tumour recurrence. The subsequent approved indications of ipilimumab for metastatic melanoma, regardless of BRAF mutational status, and other advanced/metastatic solid tumours always involve its use in association with the anti-programmed cell death protein 1 (PD-1) mAb nivolumab. Currently, ipilimumab is evaluated in ongoing clinical trials for refractory/advanced solid tumours mainly in combination with additional immunostimulating agents.

The Effects of Differentially-Expressed Homeobox Family Genes on the Prognosis and HOXC6 on Immune Microenvironment Orchestration in Colorectal Cancer

Background

The homeobox (HOX) gene family encodes highly conserved transcription factors, that play important roles in the morphogenesis and embryonic development of vertebrates. Mammals have four similar HOX gene clusters, HOXA, HOXB, HOXC, and HOXD, which are located on chromosomes 7, 17,12 and 2 and consist of 38 genes. Some of these genes were found to be significantly related to a variety of tumors; however, it remains unknown whether abnormal expression of the HOX gene family affects prognosis and the tumor microenvironment (TME) reshaping in colorectal cancer (CRC). Therefore, we conducted this systematic exploration to provide additional information for the above questions.

Methods

RNA sequencing data from The Cancer Genome Atlas (TCGA) and mRNA expression data from Gene Expression Omnibus (GEO) combined with online tumor analysis databases (UALCAN, TIMER, PrognoScan) were utilized to explore the relationship among abnormal expression of HOX family genes, prognosis and the tumor immune microenvironment in CRC.

Results

1. Differential expression and prognosis analysis: 24 genes were significantly differentially expressed in CRC compared to adjacent normal tissues, and seven upregulated genes were significantly associated with poor survival. Among these seven genes, univariate and multivariate Cox regression analysis revealed that only high expression of HOXC6 significantly contributed to poor prognosis; 2. The influence of overexpressed HOXC6 on the pathway and TME: High HOXC6 expression was significantly related to the cytokine pathway and expression of T cell attraction chemokines, the infiltration ratio of immune cells, expression of immune checkpoint markers, tumor mutation burden (TMB) scores and microsatellite instability-high (MSI-H) scores; 3. Stratified analysis based on stages: In stage IV, HOXC6 overexpression had no significant impact on TMB, MSI-H, infiltration ratio of immune cells and response prediction of immune checkpoint blockers (ICBs), which contributed to significantly poor overall survival (OS).

Conclusion

Seven differentially expressed HOX family genes had significantly worse prognoses. Among them, overexpressed HOXC6 contributed the most to poor OS. High expression of HOXC6 was significantly associated with high immunogenicity in nonmetastatic CRC. Further research on HOXC6 is therefore worthwhile to provide potential alternatives in CRC immunotherapy.

Immune Checkpoint Inhibitors in Mismatch Repair Proficient/Microsatellite Stable Metastatic Colorectal Cancer Patients: Insights from the AtezoTRIBE and MAYA Trials

Simple Summary

Immune-checkpoint inhibitors (ICI) show modest activity and efficacy in microsatellite stable (MSS) metastatic colorectal cancer (mCRC) patients harbouring a proficient mismatch repair system (pMMR). Recently, two phase 2 trials -AtezoTRIBE and MAYA- have challenged this dogma through the administration of an intense first-line chemotherapy backbone consisting of FOLFOXIRI/bevacizumab in patients unselected for their microsatellite status, and immune priming with temozolomide in chemorefractory pMMR/MSS patients with silencing of O6-methylguanine-DNA methyltransferase (MGMT), respectively, reporting promising results. We here present the founding biological rationale of these two studies and their main findings. At the same time, we stress their strengths and drawbacks and open questions still to be address in future clinical investigations.

Abstract

In metastatic colorectal cancer (mCRC), remarkable advances have been achieved with immune checkpoint inhibitors (ICIs) targeting PD-1/PD-L1 and CTLA-4, only in a small subset of tumours (4–5%), harbouring a deficient mismatch repair system (dMMR)/microsatellite instability–high (MSI-H) or mutations in the catalytic subunit of polymerase epsilon (POLE). Within this framework, several combination strategies have been investigated to sensitize proficient mismatch repair (pMMR)/microsatellite stable (MSS) mCRC to ICIs, with disappointing results so far. However, at the last ESMO meeting, two phase II trials AtezoTRIBE and MAYA provided promising results in this field. In the comparative AtezoTRIBE trial, the addition of atezolizumab to FOLFOXIRI (5-fluoruracil, oxaliplatin and irinotecan) and bevacizumab led to a significant advantage in terms of progression free survival (PFS) in a population of untreated mCRC patients, not selected according to MMR/MSI status. In the single-arm MAYA trial, immune priming with temozolomide in pMMR/MSS chemo-resistant mCRC patients with silencing of O6-methylguanine-DNA methyltransferase (MGMT) allowed reporting signals of sensitivity to the subsequent therapy with nivolumab and a low dose of ipilimumab in some patients. Here, we discuss the rationale, results, criticisms and research perspectives opened by these two studies.

Combined Treatment with Immunotherapy-Based Strategies for MSS Metastatic Colorectal Cancer

In recent years, deepening knowledge of the complex interactions between the immune system and cancer cells has led to the advent of effective immunotherapies that have revolutionized the therapeutic paradigm of several cancer types. However, colorectal cancer (CRC) is one of the tumor types in which immunotherapy has proven less effective. While there is solid clinical evidence for the therapeutic role of immune checkpoint inhibitors in mismatch repair-deficient (dMMR) and in highly microsatellite instable (MSI-H) metastatic CRC (mCRC), blockade of CTLA-4 or PD-L1/PD-1 as monotherapy has not conferred any major clinical benefit to patients with MMR-proficient (pMMR) or microsatellite stable (MSS) mCRC, reflecting 95% of the CRC population. There thus remains a high unmet medical need for the development of novel immunotherapy approaches for the vast majority of patients with pMMR or MSS/MSI-low (MSI-L) mCRC. Defining the molecular mechanisms for immunogenicity in mCRC and mediating immune resistance in MSS mCRC is needed to develop predictive biomarkers and effective therapeutic combination strategies. Here we review available clinical data from combinatorial therapeutic approaches using immunotherapy-based strategies for MSS mCRC.

The Colorectal Cancer Tumor Microenvironment and Its Impact on Liver and Lung Metastasis

Simple Summary

Colorectal cancer (CRC) is the third most common cancer worldwide. Metastasis to secondary organs, such as the liver and lungs, is a key driver of CRC-related mortality. The tumor microenvironment, which consists of the primary cancer cells, as well as associated support and immune cells, significantly affects the behavior of CRC cells at the primary tumor site, as well as in metastatic lesions. In this paper, we review the role of the individual components of the tumor microenvironment on tumor progression, immune evasion, and metastasis, and we discuss the implications of these components on antitumor therapies.

Abstract

Colorectal cancer (CRC) is the third most common malignancy and the second most common cause of cancer-related mortality worldwide. A total of 20% of CRC patients present with distant metastases, most frequently to the liver and lung. In the primary tumor, as well as at each metastatic site, the cellular components of the tumor microenvironment (TME) contribute to tumor engraftment and metastasis. These include immune cells (macrophages, neutrophils, T lymphocytes, and dendritic cells) and stromal cells (cancer-associated fibroblasts and endothelial cells). In this review, we highlight how the TME influences tumor progression and invasion at the primary site and its function in fostering metastatic niches in the liver and lungs. We also discuss emerging clinical strategies to target the CRC TME.

Landscape of the oncogenic role of fatty acid synthase in human tumors

Background: Identifying a unique and common regulatory pathway that drives tumorigenesis in cancers is crucial to foster the development of effective treatments. However, a systematic analysis of fatty acid synthase across pan-cancers has not been carried out.

Methods: We investigated the oncogenic roles of fatty acid synthase in 33 cancers based on the cancer genome atlas and gene expression omnibus.

Results: Fatty acid synthase is profoundly expressed in most cancers and is an important factor in predicting the outcome of cancer patients. Further, the level of S207 phosphorylation was found to be improved in several neoplasms (e.g., colon cancer). Fatty acid synthase expression is related to tumor-infiltrating immune cells in tumors (e.g., CD8+ T-cell infiltration level in cervical squamous cell carcinoma). Moreover, hormone receptor binding- and fatty acid metabolic process-associated pathways are involved in the functional mechanisms of fatty acid synthase.

Conclusions: This study provides a complete understanding of the oncogenic role of fatty acid synthase in human tumors.

Clinical experience with CTLA-4 blockade for cancer immunotherapy: From the monospecific monoclonal antibody ipilimumab to probodies and bispecific molecules targeting the tumor microenvironment

The immune checkpoint cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) is an inhibitory regulator of T-cell mediated responses that has been investigated as target of monoclonal antibodies (mAbs) for cancer immunotherapy. The anti-CTLA-4 mAb ipilimumab represents the first immune checkpoint inhibitor that significantly improved overall survival in patients with unresectable/metastatic melanoma. The subsequent approved indications (often in the first-line setting) for melanoma and other advanced/metastatic solid tumors always require ipilimumab combination with nivolumab, an anti-programmed cell death protein 1 (PD-1) mAb. However, the improved clinical efficacy of the mAb combination is associated with increased immune-related adverse events, which might require treatment discontinuation even in responding patients. This drawback is expected to be overcome by the recent development of anti-CTLA-4 probodies proteolitycally activated in the tumor microenvironment and bispecific molecules targeting both CTLA-4 and PD-1, whose co-expression is characteristic of tumor-infiltrating T cells. These molecules would preferentially stimulate immune responses against the tumor, reducing toxicity toward normal tissues.

Circulating Tumor DNA and Minimal Residual Disease (MRD) in Solid Tumors: Current Horizons and Future Perspectives

Circulating tumor DNA (ctDNA) is cell-free DNA (cfDNA) fragment in the bloodstream that originates from malignant tumors or circulating tumor cells. Recently, ctDNA has emerged as a promising non-invasive biomarker in clinical oncology. Analysis of ctDNA opens up new avenues for individualized cancer diagnosis and therapy in various types of tumors. Evidence suggests that minimum residual disease (MRD) is closely associated with disease recurrence, thus identifying specific genetic and molecular alterations as novel MRD detection targets using ctDNA has been a research focus. MRD is considered a promising prognostic marker to identify individuals at increased risk of recurrence and who may benefit from treatment. This review summarizes the current knowledge of ctDNA and MRD in solid tumors, focusing on the potential clinical applications and challenges. We describe the current state of ctDNA detection methods and the milestones of ctDNA development and discuss how ctDNA analysis may be an alternative for tissue biopsy. Additionally, we evaluate the clinical utility of ctDNA analysis in solid tumors, such as recurrence risk assessment, monitoring response, and resistance mechanism analysis. MRD detection aids in assessing treatment response, patient prognosis, and risk of recurrence. Moreover, this review highlights current advancements in utilizing ctDNA to monitor the MRD of solid tumors such as lung cancer, breast cancer, and colon cancer. Overall, the clinical application of ctDNA-based MRD detection can assist clinical decision-making and improve patient outcomes in malignant tumors.

Radiation therapy enhances immunotherapy response in microsatellite stable colorectal and pancreatic adenocarcinoma in a phase II trial

Overcoming intrinsic resistance to immune checkpoint blockade for microsatellite stable (MSS) colorectal cancer (CRC) and pancreatic ductal adenocarcinoma (PDAC) remains challenging. We conducted a single-arm, non-randomized, phase II trial (NCT03104439) combining radiation, ipilimumab and nivolumab to treat patients with metastatic MSS CRC (n = 40) and PDAC (n = 25) with an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1. The primary endpoint was disease control rate (DCR) by intention to treat. DCRs were 25% for CRC (ten of 40; 95% confidence interval (CI), 13-41%) and 20% for PDAC (five of 25; 95% CI, 7-41%). In the per-protocol analysis, defined as receipt of radiation, DCR was 37% (ten of 27; 95% CI, 19-58%) in CRC and 29% (five of 17; 95% CI, 10-56%) in PDAC. Pretreatment biopsies revealed low tumor mutational burden for all samples but higher numbers of natural killer (NK) cells and expression of the HERVK repeat RNA in patients with disease control. This study provides proof of concept of combining radiation with immune checkpoint blockade in immunotherapy-resistant cancers.

Neoadjuvant immunotherapy in primary and metastatic colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is the second most common solid organ cancer. Traditional treatment is with surgery and chemotherapy. Immunotherapy has recently emerged as a neoadjuvant therapy that could change treatment strategy in both primary resectable and metastatic CRC.

METHODS

A literature review of PubMed with a focus on studies exploring upfront immunotherapy in operable CRC, either for primary resectable stage I-III cancers or for (potentially) operable liver metastasis.

RESULTS

Immune checkpoint blockade by the programmed cell death 1 (PD-1) receptor inhibitors nivolumab and pembrolizumab and the cytotoxic T cell-associated protein 4 (CTLA-4) inhibitor ipilimumab has shown good results in both early-stage and advanced CRC. The effects of immune checkpoint inhibitors have so far been demonstrated in small phase I/II studies and predominantly in treatment-refractory stage IV disease with defect Mismatch repair (dMMR). However, recent data from phase I/II (NICHE-1) studies suggest an upfront role for immunotherapy in operable stage I-III disease. By blocking crucial immune checkpoints, cytotoxic T cells are activated and release cytotoxic signals that initiate cancer cell destruction. The very high complete response rate in dMMR operable CRC with neoadjuvant immunotherapy with nivolumab and ipilimumab, and even partial pathological response in some patients with proficient MMR (pMMR) CRC, calls for further attention to patient selection for neoadjuvant treatment, beyond MMR status alone.

CONCLUSION

Early data on the effect of immunotherapy in CRC provide new strategic thinking of treatment options in CRC for both early-stage and advanced disease, with prospects for new trials.

Immunotherapy in colorectal cancer: current achievements and future perspective

Following dramatic success in many types of advanced solid tumors, interest in immunotherapy for the treatment of colorectal cancer (CRC) is increasingly growing. Given the compelling long-term durable remission, two programmed cell death 1 (PD-1)-blocking antibodies, pembrolizumab and nivolumab (with or without Ipilimumab), have been approved for the treatment of patients with metastatic colorectal cancer (mCRC) that is mismatch-repair-deficient and microsatellite instability-high (dMMR-MSI-H). Practice-changing results of several randomized controlled trials to move immunotherapy into the first-line treatment for MSI-H metastasis cancer and earlier stage were reported successively in the past 2 years. Besides, new intriguing advances to expand the efficacy of immunotherapy to mCRC that is mismatch-repair-proficient and low microsatellite instability (pMMR-MSI-L) demonstrated the potential benefits for the vast majority of mCRC cases. Great attention is also paid to the advances in cancer vaccines and adoptive cell therapy (ACT). In this review, we summarize the above progresses, and also highlight the current predictive biomarkers of responsiveness in immunotherapy with broad clinical utility.

Tumor Mutational Burden Predicting the Efficacy of Immune Checkpoint Inhibitors in Colorectal Cancer: A Systematic Review and Meta-Analysis

Objectives

For colorectal cancer patients, traditional biomarker deficient mismatch repair/microsatellite instability (dMMR/MSI) is an accurate predictor of immune checkpoint inhibitors (ICIs). Recent years, researchers considered tumor mutation burden (TMB) as another predictive biomarker which means the number of nonsynonymous mutations in cancer cells. Several studies have proven that TMB can evaluate the efficacy of ICI therapy in diverse types of cancer, especially in non-small cell lung cancer and melanoma. However, studies on the association between TMB and the response to ICI therapy in colorectal cancer alone are still lacking. In this study, we aim to verify the effect of TMB as a biomarker in predicting the efficacy of ICIs in colorectal cancer.

Methods

We searched the PubMed and Ovid MEDLINE databases up to May 1, 2021 and screened studies for eligibility. Thirteen studies published from 2015 to 2021 with 5062 patients were included finally. We extracted and calculated hazard ratios (HRs) and odds ratios (ORs) of overall survival (OS) and objective response rates (ORRs) and their 95% confidence intervals (95% CIs). Pooled HR and OR were evaluated to compare OS and ORR between TMB-high and TMB-low groups in colorectal cancer patients. Meanwhile, we assessed heterogeneity with the I² statistic and p-values and performed publication bias assessments, sensitivity analyses, and subgroup analyses to search the cause of heterogeneity.

Results

The TMB-high patient group had a longer OS than the TMB-low patient group (HR = 0.68, 95% CI: 0.51, 0.92, p = 0.013) among colorectal cancer patients receiving ICIs. In addition, the TMB-high patient group was superior in terms of ORR (OR = 19.25, 95% CI: 10.06, 36.82, p < 0.001) compared to the TMB-low patient group.

Conclusions

In conclusion, this meta-analysis revealed that TMB can be used as a potential predictive biomarker of colorectal cancer patients receiving ICI therapy. Nevertheless, this finding is not stable enough. Therefore, many more randomized controlled trials are needed to prove that TMB is reliable enough to be used clinically to predict the efficacy of immunotherapy in colorectal cancer. And the most relevant biomarker remains to be determined when TMB high overlaps with other biomarkers like MSI and TILs.

The Prognostic Value of ctDNA and bTMB on Immune Checkpoint Inhibitors in Human Cancer

Background

Circulating tumor DNA (ctDNA) levels and blood tumor mutation burden (bTMB) have a significant impact on the prognosis of tumor patients. However, their prognostic role in immune checkpoint inhibitors (ICIs) in cancer patients is still unclear.

Methods

We used the Review Manager software (version 5.3) to perform a meta-analysis based on the published literature to explore the prognostic value of ctDNA and bTMB in patients receiving immunotherapy. We extracted the hazard ratios (HRs) of progression-free survival (PFS) and overall survival (OS) for each included study and their respective 95% confidence intervals (CIs) and p-values for analysis.

Results

Thirteen studies were included in the meta-analysis. Higher ctDNA levels were significantly associated with shorter OS (HR = 3.35, 95%CI = 2.49–4.51, p < 0.00001) and PFS (HR = 3.28, 95%CI = 2.47–4.35, p < 0.00001). The results of ctDNA subgroup analysis showed that high posttreatment ctDNA levels significantly correlated with shorter OS in cancer patients receiving ICIs (HR = 5.09, 95%CI = 1.43–18.07, p = 0.01). Moreover, patients with ctDNA clearance had better OS (HR = 4.94, 95%CI = 2.96–8.26, p < 0.00001). Patients with high posttreatment ctDNA levels had shorter PFS (HR = 3.00, 95%CI = 2.02–4.46, p < 0.00001) and those with ctDNA clearance had longer PFS (HR = 4.61, 95%CI = 2.78–7.65, p < 0.00001). However, there was no statistically significant difference in the OS benefits between a high and a low bTMB after ICI therapy (HR = 0.68, 95%CI = 0.33–1.37, p = 0.28).

Conclusions

The host immune system and tumor burden together determine whether cancer patients can benefit from ICI therapy. Our systematic review and meta-analysis revealed for the first time that the levels of pretreatment and posttreatment ctDNA and the clearance of ctDNA can independently be used as prognostic factors for antitumor immunotherapy, while bTMB cannot. In conclusion, ctDNA levels have great potential as an assistant tool for radiological assessments to make clinical therapeutic decisions. The prognostic utility of bTMB still requires further exploration.

Integrated Profiling Identifies PLOD3 as a Potential Prognostic and Immunotherapy Relevant Biomarker in Colorectal Cancer

Procollagen-Lysine,2-Oxoglutarate 5-Dioxygenase 3 (PLOD3) is related to a variety of human diseases. However, its function in Colorectal cancer (CRC) remains uncertain. PLOD3 expression was analyzed using The Cancer Genome Atlas (TCGA) pan-cancer data. DAVID was used for enrichment analysis of PLOD3-related genes. The correlation between PLOD3 expression and immune cell infiltration was evaluated. Four expression profile datasets (GSE17536, GSE39582, GSE74602, and GSE113513) from Gene Expression Omnibus, and two proteomic datasets were used as validation cohorts for assessing the diagnostic and prognostic value of PLOD3 in CRC. What's more, we performed immunohistochemistry (IHC) staining for PLOD3 in 160 paired CRC specimens and corresponding adjacent non-tumor tissues. PLOD3 was highly expressed in many tumors including CRC. PLOD3 was upregulated in advanced stage CRCs, and high PLOD3 expression was associated with poor survival. High PLOD3 expression was associated with low levels of B cells, CD4⁺ T cells, M1 macrophages, CD8⁺ T cells, and multiple immunerelated characteristics. In addition, the high PLOD3 expression group had a higher TIDE score and a lower tumor mutation burden and microsatellite instability, indicating that patients with high PLOD3 expression may be resistant to immunotherapy. Additional datasets and IHC analysis were used to validate the diagnostic and prognostic value of PLOD3 at the mRNA and protein levels in CRC. Patients with non-response to immunotherapy showed increased PLOD3 expression in an immunotherapy treated dataset. PLOD3 is a potential biomarker for CRC diagnosis and prognosis prediction. CRCs with high PLOD3 expression may be resistant to immune checkpoint therapy.

Clinical Application of Adaptive Immune Therapy in MSS Colorectal Cancer Patients

Colorectal cancer (CRC) is one of the most common cancers worldwide. However, the treatment outcomes of immunotherapy in microsatellite-stable (MSS) CRC remain unsatisfactory. As the majority of CRC cases display a molecular MSS/mismatch repair-proficient (pMMR) profile, it is particularly meaningful to explore the clinical applications of adaptive immune therapy in MSS CRC patients. In this review, we summarized the therapeutic approaches of adoptive immune therapies, including cytokines, therapeutic cancer vaccines, adoptive T-cell therapy, and immune checkpoint inhibitors, in the treatment of MSS CRCs.

Pembrolizumab with Capox Bevacizumab in patients with microsatellite stable metastatic colorectal cancer and a high immune infiltrate: The FFCD 1703-POCHI trial

Pembrolizumab, a PD1 immune checkpoint inhibitor (ICI), was recently reported to be very effective in patients with microsatellite instable/deficient mismatch repair metastatic colorectal cancer (MSI/dMMR mCRC), unlike patients with microsatellite stable/proficient MMR (MSS/pMMR) mCRC, in whom ICIs are generally ineffective. However, about 15% of MSS/pMMR CRCs are highly infiltrated by tumour infiltrating lymphocytes. In addition, both oxaliplatin and bevacizumab have been shown to have immunomodulatory properties that may increase the efficacy of an ICI. We formulated the hypothesis that patients with MSS/pMMR mCRC with a high immune infiltrate can be sensitive to ICI plus oxalipatin and bevacizumab-based chemotherapy. POCHI is a multicenter, open-label, single-arm phase II trial to evaluate efficacy of Pembrolizumab with Capox Bevacizumab as first-line treatment of MSS/pMMR mCRC with a high immune infiltrate for which we plan to enrol 55 patients. Primary endpoint is progression-free survival (PFS) at 10 months, which is expected greater than 50%, but a 70% rate is hoped for. Main secondary objectives are overall survival, secondary resection rate and depth of response. Patients must have been resected of their primary tumour so as to evaluate two different immune scores (Immunoscore® and TuLIS) and are eligible if one score is "high". The first patient was included on April 20, 2021.

Combined CTLA-4 and PD-L1 blockade in patients with chemotherapy-naïve metastatic castration-resistant prostate cancer is associated with increased myeloid and neutrophil immune subsets in the bone microenvironment

BACKGROUND

Immune checkpoint therapy (ICT) has low response rates in patients with metastatic castration-resistant prostate cancer (mCRPC), in part due to few T cells in the tumor microenvironment (TME). Anti-cytotoxic T lymphocyte-associated protein 4 (CTLA-4) promotes intratumoral T cell infiltration but induces upregulation of PD-1 and programmed death ligand-1 (PD-L1) within the prostate TME. Combined anti-CTLA-4 plus anti-PD-1 can partly overcome this adaptive resistance and was recently shown to augment responses in patients with mCRPC with measurable disease. Although bone is the most common site of metastasis in prostate cancer, patients with bone-predominant disease are frequently excluded from trials because they lack measurable disease, which limits assessment of disease progression and tissue sampling. We therefore designed this study to investigate combined ICT in mCRPC to bone.

HYPOTHESIS

Combined anti-CTLA-4 (tremelimumab) plus anti-PD-L1 (durvalumab) is safe and well tolerated in patients with chemotherapy-naïve mCRPC to bone.

PATIENTS AND METHODS

In this single-arm pilot study, men with chemotherapy-naïve mCRPC to bone received tremelimumab (75 mg intravenous) plus durvalumab (1500 mg intravenous) every 4 weeks (up to four doses), followed by durvalumab (1500 mg intravenous) maintenance every 4 weeks (up to nine doses). The primary endpoint was incidence of adverse events. Secondary endpoints included serum prostate-specific antigen (PSA), progression-free survival (PFS), radiographic PFS (rPFS), and maximal PSA decline.

RESULTS

Twenty-six patients were treated between August 8, 2017 and March 28, 2019. Grade ≥3 treatment-related adverse events (TRAEs) occurred in 11 patients (42%), with no grade 4 or 5 events. TRAEs leading to discontinuation occurred in three patients (12%). PSA decline ≥50% occurred in three patients (12%). Six patients (24%) achieved stable disease for >6 months. At a median follow-up of 43.6 months, median rPFS was 3.7 months (95% CI: 1.9 to 5.7), and median overall survival was 28.1 months (95% CI: 14.5 to 37.3). Post-treatment evaluation of the bone microenvironment revealed transcriptional upregulation in myeloid and neutrophil immune subset signatures and increased expression of inhibitory immune checkpoints.

CONCLUSIONS

Tremelimumab plus durvalumab was safe and well tolerated in patients with chemotherapy-naïve mCRPC to bone, with potential activity in a small number of patients as measured by rPFS. Combination of CTLA-4 and PD-L1 blockade with therapies targeting the myeloid compartment or other inhibitory immune receptors may be necessary to overcome mechanisms of resistance within prostate bone microenvironment.

TRIAL REGISTRATION NUMBER

NCT03204812.

TAS-116 (Pimitespib), an Oral HSP90 Inhibitor, in Combination with Nivolumab in Patients with Colorectal Cancer and Other Solid Tumors: An Open-Label, Dose-Finding, and Expansion Phase Ib Trial (EPOC1704)

PURPOSE

This is a phase Ib trial of TAS-116, an oral HSP90 inhibitor, plus nivolumab for colorectal cancer and other solid tumors.

PATIENTS AND METHODS

Enrolled patients received TAS-116 plus nivolumab in a dose-finding part to estimate the recommended dose. Additional patients were enrolled in a dose-expansion part. TAS-116 monotherapy (orally once daily, 80-160 mg) was administered for 2 weeks followed by the combination with nivolumab (intravenously every 2 weeks, 3 mg/kg). The primary endpoint was dose-limiting toxicities (DLT). We also conducted biomarker research using paired samples from repeated blood collections and tumor biopsies.

RESULTS

A total of 44 patients with colorectal cancer (n = 29), gastric cancer (n = 8), sarcoma (n = 5), non-small cell lung cancer (n = 1), and melanoma (n = 1) were enrolled. Eleven patients had previously received immune-checkpoint inhibitors. No DLTs were observed at all dose levels, and TAS-116 160 mg was determined as recommended dose. The common grade 3 or worse treatment-related adverse events included liver transaminase increased (7%), creatinine increased (5%), and platelet count decreased (5%). Objective tumor response was observed in 6 patients, including 4 microsatellite stable (MSS) colorectal cancers, 1 microsatellite instability-high colorectal cancer, and 1 leiomyosarcoma, resulting in an objective response rate of 16% in MSS colorectal cancer without prior immune-checkpoint inhibitors. Biomarker analysis showed that TAS-116 inhibited the activity of regulatory T cells in peripheral blood mononuclear cells and tumor-infiltrating lymphocytes.

CONCLUSIONS

TAS-116 160 mg plus nivolumab had manageable safety profiles and antitumor activity, especially for MSS colorectal cancer patients.

Combination Immunotherapies to Overcome Intrinsic Resistance to Checkpoint Blockade in Microsatellite Stable Colorectal Cancer

Although immune checkpoint inhibitors (ICIs) have shown promising results in the treatment of treating various malignancies, progress has been severely limited in metastatic colorectal cancer (mCRC). ICIs are effective in a fraction of patients with microsatellite instability-high mCRC but have little clinical efficacy in patients with microsatellite stable (MSS) mCRC, which accounts for 95% of mCRC cases. MSS mCRCs are considered to have intrinsic resistance to ICI monotherapy through multiple mechanisms. (1) They are poorly immunogenic because of their low tumor mutation burden; (2) frequent activation of the WNT/β-catenin signaling pathway excludes intratumoral CD8+ T cell immunity; (3) the tumor microenvironment is immunosuppressive because of the presence of various immunosuppressive cells, including tumor-associated macrophages and regulatory T cells; and (4) frequent liver metastasis in MSS mCRC may reduce the efficacy of ICIs. To overcome these resistance mechanisms, combination approaches using various agents, including STING agonists, MEK inhibitors, VEGF/R inhibitors, WNT/β-catenin inhibitors, oncolytic viruses, and chemo/radiotherapy, are actively ongoing. Preliminary evidence of the efficacy of some has been shown in early clinical trials. This review summarizes novel combination immunotherapy strategies described in recent preclinical and clinical studies to overcome the limitations of ICI monotherapy in MSS mCRC.

Application of immune checkpoint inhibitors in colorectal cancer

Over the past decade, immunotherapy has been shown to have antitumor activity in a variety of solid tumors, such as melanoma, renal cell carcinoma, and non-small cell lung cancer, keeping a lead in a new era of tumor immunotherapy. Colorectal cancer with high microsatellite instability (MSI-H) or mismatch repair deficient (dMMR) is sensitive to immune checkpoint inhibitors (ICIs). ICIs monotherapy and ICIs combination therapy have made breakthroughs in the treatment of MSI-H/dMMR CRC. At present, a variety of ICIs have been approved for first- and post-line treatment in patients with CRC. However, MSI-H/dMMR type tumors only account for 5% of metastatic CRC, and the most CRCs were microsatellite stable (MSS) or mismatch repair proficient (pMMR). Many clinical trials are exploring effective treatments for patients with MSS/pMMR CRC, and the combination of ICIs and drugs with different mechanisms is expected to improve the efficacy of MSS/pMMR CRC patients. In the future, attention should be paid to finding the potential therapeutic markers of ICIs and the drug resistance mechanism of ICIs, so as to break through the immune tolerance of MSS/pMMR CRC patients.

Immune-Checkpoint Inhibitors for Metastatic Colorectal Cancer: A Systematic Review of Clinical Outcomes

Simple Summary

In 2018, colorectal cancer (CRC) was declared the fourth most deadly cancer worldwide. Unfortunately, a quarter of all patients are diagnosed at late stages, when curative surgery is not possible, rendering systemic therapy and/or best supportive care as the only options. To our knowledge, this is the first systematic review assessing response and survival rates in patients with mCRC treated with immune-checkpoint inhibitors (ICIs). Our study established that ICIs show potentially superior response rates in mCRC patients, though only in those with high microsatellite instability (MSI). Nivolumab + regorafenib was reported to provide encouraging response in low-MSI (MSI-L) patients; however, additional studies using cohort randomization are required. Further studies are required, particularly regarding the mechanism of resistance to ICIs in MSI-L patients.

Abstract

Background. Colorectal cancer (CRC) is the fourth most deadly cancer worldwide. Unfortunately, a quarter of the patients are diagnosed at late stages, when surgical options are limited. Targeted therapies, particularly immune-checkpoint inhibitors (ICIs), are the latest addition and have been studied herein regarding their efficacy outcomes. Methods. Clinical studies were identified through the PubMed, Scopus and Cochrane databases. Any trial that evaluated ICIs in patients with metastatic CRC (mCRC) and reported the objective response rate was deemed eligible. Data analysis was performed by employing the random-effects model in STATA v.17. Results. A total of 461 articles were identified; 13 clinical trials were included, encompassing a total cohort of 1209 patients. Our study determined that a single PD-1/PD-L1 checkpoint blockade provides durable clinical response in mCRC patients with high microsatellite instability (MSI-H). The combinatorial therapy of CTLA-4 + PD-1 inhibitors also showed high response rates in pre-treated MSI-H patients. The single-arm REGONIVO trial reported durable clinical response in patients with microsatellite stable (MSS) status. Conclusions. Our study surmises that PD-1/PD-L1 inhibitors as well as combination therapy with CTLA-4 and PD-1 inhibitors show encouraging response rates in mCRC patients, albeit exclusively in patients with cancer that are of MSI-H status. A single study suggests that nivolumab + regorafenib can reach a durable response rate in MSS patients; however, further studies in larger randomized settings are required.

Immune Checkpoint Inhibitors in Colorectal Cancer: Challenges and Future Prospects

Immunotherapy is a new pillar of cancer therapy that provides novel opportunities to treat solid tumors. In this context, the development of new drugs targeting immune checkpoints is considered a promising approach in colorectal cancer (CRC) treatment because it can be induce specific and durable anti-cancer effects. Despite many advances in the immunotherapy of CRC, there are still limitations and obstacles to successful treatment. The immunosuppressive function of the tumor microenvironment (TME) is one of the causes of poor response to treatment in CRC patients. For this reason, checkpoint-blocking antibodies have shown promising outcomes in CRC patients by blocking inhibitory immune checkpoints and enhancing immune responses against tumors. This review summarizes recent advances in immune checkpoint inhibitors (ICIs), such as CTLA-4, PD-1, PD-L1, LAG-3, and TIM-3 in CRC, and it discusses various therapeutic strategies with ICIs, including the double blockade of ICIs, combination therapy of ICIs with other immunotherapies, and conventional treatments. This review also delineates a new hopeful path in the combination of anti-PD-1/anti-PD-L1 with other ICIs such as anti-CTLA-4, anti-LAG-3, and anti-TIM-3 for CRC treatment.

Nanotherapeutic approach to tackle chemotherapeutic resistance of cancer stem cells

Estimates indicate that cancer will become the leading cause of mortality worldwide in the future. Tumorigenesis is a complex process that involves self-sufficiency in signs of growth, insensitivity to anti-growth signals, prevention of apoptosis, unlimited replication, sustained angiogenesis, tissue invasion, and metastasis. Cancer stem cells (CSCs) have an important role in tumor development and resistance. Here we will approach phenotypic plasticity capacity, highly efficient DNA repair systems, anti-apoptotic machinery, sustained stemness features, interaction with the tumor microenvironment, and Notch, Wnt, and Hedgehog signaling pathways. The researches about CSCs as a target in cancer treatment has been growing. Many different options have pointed beneficial results, such as pathways and CSC-surface markers targeting. Besides its limitations, nanotherapeutics have emerged as a potential strategy in this context since they aim to improve pharmacokinetics, biodistribution, and reduce the side effects observed in traditional treatments. Nanoparticles have been studied in this field, mostly for drug delivery and a multitherapy approach. Another widely researched approaches in this area are related to heat therapy, such as photothermal therapy, photodynamic therapy and magnetic hyperthermia, besides molecular targeting. This review will contemplate the most relevant studies that have shown the effects of nanotherapeutics. In conclusion, although the studies analyzed are mostly preclinical, we believe that there is strong evidence that nanoparticles can increase the chances of a better prognosis to cancer in the future. It is also essential to transpose these findings to the clinic to confirm and better understand the role of nanotherapeutics in this context.

Immunotherapy in colorectal cancer: is the long-awaited revolution finally happening?

Immunotherapy has recently become a major treatment modality for several types of solid tumours, achieving remarkable and long-lasting remissions. In metastatic colorectal cancer patients (mCRC), immune checkpoint inhibitors (ICIs) were found to be effective as treatment for deficient mismatch repair (dMMR)/ microsatellite instability high (MSI-H) tumours and received regulatory approval for this indication. However, mCRC is a complex disease and dMMR/MSI-H tumours represent a minority of the cases; therefore, new strategies are needed to extend the benefits of immunotherapy to a larger population of patients. This review explores the immunological differences between dMMR/MSI-H and proficient mismatch repair (pMMR)/ microsatellite instability low (MSI-L) tumours, focuses on new proposed biomarkers to predict response to immunotherapy and illustrates results reported from the main clinical trials with immunotherapeutic agents in CRC, addressing the most promising approaches being currently developed.

Clinical Response to Immunotherapy Targeting Programmed Cell Death Receptor 1/Programmed Cell Death Ligand 1 in Patients With Treatment-Resistant Microsatellite Stable Colorectal Cancer With and Without Liver Metastases

IMPORTANCE

Microsatellite stable (MSS) metastatic colorectal cancer has been historically characterized as resistant to immunotherapy. Recent studies have demonstrated limited clinical activity of programmed cell death receptor 1/programmed death ligand 1 (PD-1/PD-L1) targeting in MSS metastatic colorectal cancer. The association of metastatic disease in the liver with treatment response has not been fully investigated.

OBJECTIVE

To investigate the association of liver metastases with response to PD-1/PD-L1-targeting therapy in MSS metastatic colorectal cancer.

DESIGN, SETTING, AND PARTICIPANTS

This single-center retrospective cohort study evaluated clinical responses to PD-1- or PD-L1-targeting therapy, with or without other investigational agents, in patients with MSS metastatic colorectal cancer and disease progression after standard of care therapy from January 1, 2014, to December 31, 2020.

MAIN OUTCOMES AND MEASURES

Objective response rate (ORR) and progression-free survival (PFS), measured from initiation of PD-1/PD-L1-targeting therapy.

RESULTS

Ninety-five patients with MSS metastatic colorectal cancer were identified (54 men [56.8%]; median age, 55 [interquartile range (IQR), 49-64] years). The overall ORR was 8.4% (8 of 95 patients). Eight of 41 patients without liver metastases achieved an ORR of 19.5%, and no response was observed in 54 patients with liver metastases. The disease control rate was 58.5% (24 of 41) in patients without liver metastasis and 1.9% (1 of 54) in patients with liver metastasis. Patients without liver metastases at the time of PD-1/PD-L1-targeting treatment had a superior median PFS compared with patients with liver metastases (4.0 [IQR, 2.0-7.5] vs 1.5 [IQR, 1.0-2.0] months; P < .001). In addition, median PFS was 5.5 (IQR, 2.0-11.5) months for patients without any prior or current liver involvement at the time of PD-1/PD-L1-targeting treatment initiation. Using a multivariate Cox regression model correcting for Eastern Cooperative Oncology Group status, primary tumor location, RAS and BRAF status, tumor mutation burden, and metastatic sites, liver metastases was the variable with the most significant association with faster progression after PD-1/PD-L1 treatment inhibition (hazard ratio, 7.00; 95% CI, 3.18-15.42; P < .001).

CONCLUSIONS AND RELEVANCE

Findings of this cohort study suggest that patients with MSS metastatic colorectal cancer and without liver metastases may derive clinical benefits from checkpoint inhibitors, whereas the presence of liver metastases was associated with resistance. Further prospective studies are needed to investigate PD-1/PD-L1 inhibitors in patients with MSS metastatic colorectal cancer without liver metastases.

Functionalized DMP-039 Hybrid Nanoparticle as a Novel mRNA Vector for Efficient Cancer Suicide Gene Therapy

Background

Gene therapy has emerged as a new strategy for cancer therapy. As an alternative nucleic acid material, messenger ribonucleic acid (mRNA) is being increasingly utilized in cancer gene therapy. However, unfulfilled requirements and a lack of ideal mRNA delivery vectors persist.

Methods

We developed an advanced mRNA delivery system, DMP-039, by fusing a cell-penetrating peptide, cRGD-R9, and a cationic nano-sized DMP backbone together. The DMP gene vector backbone was synthesized by the self-assembly of DOTAP lipid and mPEG-PCL polymer. Introduction of the cRGD-R9 peptide onto the DMP backbone was performed to elevate the mRNA delivery capacity, which resulted in a peptide-functionalized hybrid delivery system.

Results

The average size of the synthesized DMP-039 was 268.9 ± 12.4 nm (PDI = 0.382), with a potential of 17.4 ± 0.5 mV. The synthesized DMP-039 hybrid nanoparticles exhibited high mRNA delivery efficiency through multiple mechanisms during transmembrane transportation. By loading the encoding mRNA from the suicide gene Bim, a locally administered mBim/DMP-039 complex strongly inhibited growth in two colon cancer models. Moreover, intravenous administration of the mBim/DMP-039 complex efficiently suppressed C26 pulmonary metastatic tumor progression with high safety. The in vivo distribution, degradation, and excretion were also investigated in detail.

Conclusion

Our results suggest that the DMP-039 peptide-functionalized hybrid nanoparticle is an advanced candidate for mRNA-based suicide gene therapy.

Targeting Metastatic Colorectal Cancer with Immune Oncological Therapies

Metastatic colorectal cancer carries poor prognosis, and current therapeutic regimes convey limited improvements in survival and high rates of detrimental side effects in patients that may not stand to benefit. Immunotherapy has revolutionised cancer treatment by restoring antitumoural mechanisms. However, the efficacy in metastatic colorectal cancer, is limited. A literature search was performed using Pubmed (Medline), Web of Knowledge, and Embase. Search terms included combinations of immunotherapy and metastatic colorectal cancer, primarily focusing on clinical trials in humans. Analysis of these studies included status of MMR/MSS, presence of combination strategies, and disease control rate and median overall survival. Evidence shows that immune checkpoint inhibitors, such as anti-PD1 and anti-PD-L1, show efficacy in less than 10% of patients with microsatellite stable, MMR proficient colorectal cancer. In the small subset of patients with microsatellite unstable, MMR deficient cancers, response rates were 40-50%. Combination strategies with immunotherapy are under investigation but have not yet restored antitumoural mechanisms to permit durable disease regression. Immunotherapy provides the potential to offer additional strategies to established chemotherapeutic regimes in metastatic colorectal cancer. Further research needs to establish which adjuncts to immune checkpoint inhibition can unpick resistance, and better predict which patients are likely to respond to individualised therapies to not just improve response rates but to temper unwarranted side effects.

Personalized Therapy and Liquid Biopsy-A Focus on Colorectal Cancer

(1) Background: Resistance mechanisms represent a barrier to anti-cancer therapies. Liquid biopsies would allow obtaining additional information in order to develop targeted therapies to thwart the resistance phenomena but also to follow in time real response to treatment and be able to adapt it the most quickly possible way in case of resistance. (2) Methods: herein we summarize the different liquid biopsies which are currently under research; we then review the literature and focalize on one of their potential roles: the theranostic one and especially in the cases of colorectal cancers. (3) Results: few studies targeting liquid biopsy as a potential tool to adapt cancer treatments are present in the literature and encompass few patients. (4) Conclusions: further research is needed to prove the efficiency of LB. Indeed, it seems a promising tool to guide treatment by targeting actionable mutations with detection of resistant mutations.

Cell-based immunotherapy approaches for colorectal cancer: main achievements and challenges

Immunotherapy is becoming as a major treatment modality for multiple types of solid tumors, including subsets of colorectal cancers (CRCs). The successes with immunotherapy alone has largely been achieved in patients with advanced-stage mismatch-repair-deficient and microsatellite instability-high (dMMR-MSI-H) CRCs. However, the benefits of immunotherapy have not been demonstrated to be effective in patients with proficient mismatch repair (pMMR) CRC, who are microsatellite-stable (MSS) or have low levels of microsatellite instability (MSI-L). Here, we provide a comprehensive review on the immune microenvironment of CRC tumors and describe the rapid pace of scientific changes. We discuss the tremendous promise of cell-based immunotherapy strategies that are under preclinical studies/clinical trials or being used in therapeutic paradigms.

Microsatellite Instability as a Predictor of Outcomes in Colorectal Cancer in the Era of Immune-Checkpoint Inhibitors

The microsatellite instable phenotype resulting from errors in DNA mismatch repair proteins accounts for as far as 15 to 20% of non-hereditary colon cancers but is scarce in rectal cancer. It has been shown that the increased existence of tumor-specific neoantigens in hypermutated tumors is correlated with higher tumor-infiltrating lymphocytes (TILs) and overexpression of immune checkpoint receptors and ligands, mainly PD-1 and PD-L1. In particular, the data gained up to now gives evidence that neoantigen recognition constitutes a dominant component in the course of immunotherapies. This review's primary objective is to describe current approvals and summarize present knowledge about the outcomes of immuno-oncology treatment of microsatellite instable colorectal cancer (CRC). The secondary objective is to give a narrative report about testing methodologies, prognostics, and the predictive value of microsatellite instability. For this purpose, a literature review was performed, focusing on published clinical trial results, ongoing clinical trials and timelines, testing methods, and prognostic and predictive value of MSI. Following four recent FDA approvals of immunotherapy of MSI-high CRC, further work should be warranted by pathology societies towards standardization and rising concordance and reproducibility across the IHC/MSI testing landscape in order to facilitate professionals to offer better survival options for patients with CRC.

The Emergence of Immune-checkpoint Inhibitors in Colorectal Cancer Therapy

Immunotherapy has revolutionized the treatment landscape in a number of solid tumors. In colorectal cancer, evidence suggests that microsatellite high (MSI-H) tumors are the most responsive to immune checkpoint blockade due to increased neo-antigen load and a favorable tumor microenvironment. Indeed, Pembrolizumab now represents a first-line option in such patients. However, MSI-H tumors represent the minority and a proportion of patients' progress despite initially responding. Trials are investigating different immunotherapy combinatorial strategies to enhance immune response in less immunogenic colorectal tumors. Such strategies include dual immune checkpoint blockade, combining immune checkpoint inhibitors with other treatment modalities such as radiotherapy, chemotherapy or other biological or targeted agents. Moreover, there is an increasing drive to identify biomarkers to better select patients most likely to respond to immunotherapy and understand intrinsic and acquired resistance mechanisms. Apart from MSI-H tumors, there is a strong rationale to suggest that tumors with alterations in DNA polymerase epsilon and DNA polymerase delta are also likely to respond to immunotherapy and trials in this subpopulation are underway. Other strategies such as priming O6-methylguanineDNA methyltransferase silenced tumors with alkylating agents to make them receptive to immune checkpoint blockade are also being investigated. Here we discuss different colorectal subpopulations together with their likelihood of response to immune checkpoint blockade and strategies to overcome barriers to a successful clinical outcome. We summarize evidence from published clinical trials and provide an overview of trials in progress whilst discussing newer immunotherapy strategies such as adoptive cell therapies and cancer vaccines.

ctDNA Clearance and Radiographic Resolution of Disease in Response to Dual Checkpoint Inhibition in Metastatic Microsatellite Stable Colorectal Cancer with a High Tumor Mutation Burden

Immunotherapy (IO) has increasingly been demonstrated to provide therapeutic benefit to patients with metastatic colorectal cancer (mCRC). However, only a subset of mCRC tumors respond to IO. Monitoring response with tumor biomarkers like carcinoembryonic antigen (CEA) has been challenging in patients with microsatellite stable (MSS) mCRC due to low expression of CEA (CEA/lo). Noninvasive blood-based biomarkers such as circulating tumor DNA (ctDNA) can inform early treatment response and augment radiographic monitoring. We describe a case study of a patient with chemotherapy-refractory CEA/lo MSS mCRC, with metastatic disease present in a cardiophrenic lymph node. The patient was given 2 cycles of combination IO (ipilimumab/nivolumab). Response was monitored by ctDNA using a multiplex PCR next-generation sequencing assay, CEA, and CT scan. After IO administration, ctDNA levels rapidly declined, becoming undetectable. This was concurrent with radiographic resolution of the lymph node metastasis. Serial monitoring of CEA during this same period was uninformative, with no significant changes observed. Significant decline in ctDNA identified metastatic response to IO in a patient with CEA/lo, MSS mCRC and was concurrently validated by CT scan. This case study provides evidence that ctDNA can be used as a prospective surrogate for radiographic tumor response.

Perspectives on Immunotherapy of Metastatic Colorectal Cancer

Colorectal cancer, especially liver metastasis, is still a challenge worldwide. Traditional treatment such as surgery, chemotherapy and radiotherapy have been difficult to be further advanced. We need to develop new treatment methods to further improve the poor prognosis of these patients. The emergence of immunotherapy has brought light to mCRC patients, especially those with dMMR. Based on several large trials, some drugs (pembrolizumab, nivolumab) have been approved by US Food and Drug Administration to treat the patients diagnosed with dMMR tumors. However, immunotherapy has reached a bottleneck for other MSS tumors, with low response rate and poor PFS and OS. Therefore, more clinical trials are underway toward mCRC patients, especially those with MSS. This review is intended to summarize the existing clinical trials to illustrate the development of immunotherapy in mCRC patients, and to provide a new thinking for the direction and experimental design of immunotherapy in the future.

Immunotherapy in colorectal cancer

The immune tumor microenvironment (TME) of colorectal cancer (CRC) is a crucial contributor to disease biology, making it an important target for therapeutic intervention. The diversity of immune cell populations within various subsets of CRC has led to the discovery that immune characterization of the TME has both prognostic and predictive value for patients. The convergence of improved molecular and cellular characterization of CRC along with the widespread use of immunotherapy in solid tumors has led to a revolution in the approach to clinical care. Monoclonal antibodies (mAbs) which target key immune checkpoints, such as programmed death-1 (PD-1) and cytotoxic T-lymphocyte antigen 4 (CTLA-4), have demonstrated remarkable clinical activity in microsatellite instability-high (MSI-H) CRCs and are now used in routine practice. The observation that MSI-H cancers are highly infiltrated with immune cells and carry a high neoantigen load led to the successful targeting of these cancers with immunotherapy. More recently, the Food and Drug Administration (FDA) approved a PD-1 inhibitor for microsatellite stable (MSS) cancers with high tumor mutation burden. However, the anti-tumor activity of immunotherapy is rare in the majority of CRC. While immune cell characterization does provide prognostic value in these patients, these observations have not yet led to therapeutic interventions. By delineating factors that predict efficacy, resistance, and therapeutic targets, ongoing research will inform the development of effective combination strategies for the vast majority of MSS CRC and immunotherapy-resistant MSI-H cancers.

High PHD Finger Protein 19 (PHF19) expression predicts poor prognosis in colorectal cancer: a retrospective study

Background

Colorectal cancer (CRC) is the third most common cancer all around the world, and it seriously threats human health. PHF19 has been proved to be closely related to the prognosis of patients in a variety of malignant tumors, but the effect of PHF19 on the prognosis evaluation of CRC patients has not been confirmed.

Methods

In our study, we used GEO, TCGA database and IHC to verify the PHF19 expression in CRC samples. Survival analysis of PHF19 based on TCGA, GEO series, and our own CRC sample were performed. Cox regression was performed to reveal the relationship between PHF19 and prognosis. Co-expression was performed to find genes related to PHF19 expression. GO/KEGG enrichment analysis and GSEA analysis were used to confirm the most relevant signal pathway to PHF19. Next, cell experiments were performed to verify the effect of PHF19 on the proliferation, invasion and metastasis of CRC. Then, Western blot was used to verify the protein expression of the above two phenotypes. Finally, tumor formation experiments in nude mice were used to verify the role of PHF19 of tumor proliferation in vivo.

Results

We found that PHF19 was significantly over-expressed in tumors compared with normal tissues. Kaplan–Meier (K–M) analysis indicated that high PHF19 in CRC associated with poor overall survival (OS) in CRC patients. Clinical correlation analysis showed that high expression of PHF19 was closely related to t umor progression in CRC patients, especially infiltration and metastasis. Bioinformatics revealed that PHF19 might affect tumor malignant phenotype by regulating the cell cycle in CRC. CCK-8 and clonal formation experiment showed that the proliferative ability of tumor cells was promoted. Flow cytometry showed that the cell cycle accelerated the transition from G1 to S phase. Western blot found that Cyclin D1, CDK4, and CDK6 expression were up-regulated. Transwell and wound-healing experiment found that invasive and migratory abilities was promoted after the over-expression of PHF19. Western blot showed that the expression of key proteins of Epithelial-Mesenchymal Transition (EMT) changed. Tumor formation experiments in nude mice showed that overexpression of PHF19 could promote tumor proliferation in vivo.

Conclusion

Our research proved that PHF19 could be an independent prognostic factor for CRC, PHF19 promoted the proliferative ability and the invasion and metastasis of CRC by up-regulating the expression of key molecules related to cell cycle and EMT pathway in vitro, promoting tumor proliferation in vivo.

Molecular and Radiological Features of Microsatellite Stable Colorectal Cancer Cases With Dramatic Responses to Immunotherapy

BACKGROUND/AIM

The majority of colorectal cancer (CRC) cases, which are microsatellite stable (MSS) and do not harbor mismatch repair deficiency/microsatellite instability, are resistant to immunotherapy. Identification of patients with exceptional responses in MSS CRC and predictive biomarkers is an unmet need that needs to be addressed.

CASE REPORT

We report three cases of MSS CRC with durable clinical benefit from immunotherapy with anti-PD-1 checkpoint inhibitors. Two cases bear a POLE P286R mutation, which has been associated with lack of immunotherapy response in MSS CRC. Two cases bear alterations in Ataxia-Telangiectasia Mutated (ATM) which may contribute to observed responses, including interaction with a co-administered intratumoral stimulator of interferon genes (STING) pathway agonist in one patient.

CONCLUSION

Novel DNA damage repair alterations, including mutations in ATM, can provide insight into additional mechanisms by which genomic alterations can sensitize MSS CRC to diverse immunotherapies.

Targeting MSS colorectal cancer with immunotherapy: are we turning the corner?

INTRODUCTION

Immunotherapy with checkpoint inhibition has shown potent antitumor activity in patients with microsatellite instability (MSI) metastatic cancer. Microsatellite stable (MSS) colorectal cancer has long been considered resistant to immunotherapy.

AREAS COVERED

In this review, we provide an overview of current progress on strategies to overcome the resistance to immunotherapy in MSS colorectal cancer.

EXPERT OPINION

Emerging evidence suggest that combination of immune modulators such as regorafenib may improve the responsiveness of MSS colorectal cancer to checkpoint blockade. In addition, signs of clinical activity have also been observed in other combination strategies, such as the combination of checkpoint blockade with Stat3 inhibitor, or bispecific T-cell engagers. Nevertheless, predictive biomarkers that can identify patients who may benefit from immunotherapy are key for its implementation in clinical setting. Metastatic disease sites may predict for the response or resistance to checkpoint blockade, with liver metastases emerging as a strong predictive biomarker of lack of benefit from PD-1 targeting, even with combination therapies. Additional efforts are required to study the mechanism of resistance and to develop novel therapeutic strategies to overcome immune resistance.

ABBREVIATIONS

CEA: carcinoembryonic antigen; CR: complete response; CTLA-4: cytotoxic T-lymphocyte-associated protein 4; DCR: disease control rate; MSI-H: microsatellite instability-high; MSS: Microsatellite stable (MSS); OS: overall survival; PD-1: programmed cell death protein 1; PD-L1: programmed death-ligand receptor 1; PR: partial response; PFS: progression-free survival; SD: stable disease; TMB: tumor mutation burden; VEGFR: vascular endothelial growth factor receptor.

Immune Checkpoint Blockade in Lower Gastrointestinal Cancers: A Systematic Review

BACKGROUND

Limited therapy options exist for patients with treatment-refractory metastatic colorectal or anal cancers, prompting investigation into alternative therapies. Immunotherapy in the form of immune checkpoint blockade is one such emerging treatment that has demonstrated promising results in other tumour streams.x This review aims to assess the current use of immune checkpoint blockade in patients with lower gastrointestinal tumours.

PATIENTS AND METHODS

Embase, Medline and Cochrane databases were searched for included studies. Clinical trials published in English and utilising immune checkpoint blockade for primary tumours situated in the lower gastrointestinal tract were included. Databases were searched for studies reporting on at least one of overall survival, progression-free survival or response to therapy.

RESULTS

In total, 972 abstracts were screened, with 10 studies included in the final review. Eight trials (833 patients) assessed immune checkpoint blockade in the setting of colorectal cancers. These included pembrolizumab, nivolumab, durvalumab, atezolizumab, tremelimumab and ipilimumab. A total of 20 patients across all studies achieved a complete response, and 111 patients achieved a partial response to treatment. Two trials (62 patients) assessed immune checkpoint blockade in anal cancer, utilising nivolumab and pembrolizumab. Two patients across both studies achieved a complete response, and 11 patients achieved a partial response.

CONCLUSIONS

A number of patients with advanced lower gastrointestinal tumours achieved a complete response to treatment for what would otherwise be considered palliative disease. Presented data have highlighted that particular patients may benefit from first-line or combination immunotherapy, and thus, further investigation is warranted to individualise treatment.

Rectosigmoid-Junction Squamous Cell Carcinoma With pMMR/MSS Achieved a Partial Response Following PD-1 Blockade Combined With Chemotherapy: A Case Report

Colorectal squamous cell carcinoma (SCC) is extremely rare and associated with a poor prognosis. And the pMMR/MSS colorectal cancer is related to a limited response to programmed death ligand-1 (PD-1) blockade monotherapy. However, the clinical activity of PD-1 blockade monotherapy or combination therapy in colorectal SCC is unknown. One patient with rectosigmoid-junction SCC was treated with PD-1 blockade combined with chemotherapy. After 3 months of PD-1 blockade and chemotherapy, the computed tomography imaging showed that this patient achieved a partial response. The next generation sequencing and immunohistochemistry analysis showed that the patient had tumors with proficient mismatch repair (pMMR) and microsatellite stability (MSS), strong PD-L1 expression, and tumor mutational burden-high (TMB-High), respectively. This case suggests that PD-1 blockade combined with chemotherapy might be an effective therapy for colorectal SCC with pMMR/MSS status. Moreover, the PD-L1 expression and TMB might be the potential predictors of PD-1 blockade response for colorectal SCC patients.

Targeting cholesterol biosynthesis promotes anti-tumor immunity by inhibiting long noncoding RNA SNHG29-mediated YAP activation

Anti-tumor immunity through checkpoint inhibitors, specifically anti-programmed death 1 (PD-1)/programmed death ligand 1 (PD-L1) interaction, is a promising approach for cancer therapy. However, as early clinical trials indicate that colorectal cancers (CRCs) do not respond well to immune-checkpoint therapies, new effective immunotherapy approaches to CRC warrant further study. Simvastatin is an inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A (CoA) reductase (HMGCR), the rate-limiting enzyme of the mevalonate (MVA) pathway for the cholesterol biosynthesis. However, little is known about the functions of simvastatin in the regulation of immune checkpoints or long noncoding RNA (lncRNA)-mediated immunoregulation in cancer. Here, we found that simvastatin inhibited PD-L1 expression and promoted anti-tumor immunity via suppressing the expression of lncRNA SNHG29. Interestingly, SNHG29 interacted with YAP and inhibited phosphorylation and ubiquitination-mediated protein degradation of YAP, thereby facilitating downregulation of PD-L1 transcriptionally. Patient-derived tumor xenograft (PDX) models and the clinicopathological analysis in samples from CRC patients further supported the role of the lncRNA SNHG29-mediated PD-L1 signaling axis in tumor microenvironment reprogramming. Collectively, our study uncovers simvastatin as a potential therapeutic drug for immunotherapy in CRC, which suppresses lncRNA SNHG29-mediated YAP activation and promotes anti-tumor immunity by inhibiting PD-L1 expression.

Are Molecular Alterations Linked to Genetic Instability Worth to Be Included as Biomarkers for Directing or Excluding Melanoma Patients to Immunotherapy?

The improvement of the immunotherapeutic potential in most human cancers, including melanoma, requires the identification of increasingly detailed molecular features underlying the tumor immune responsiveness and acting as disease-associated biomarkers. In recent past years, the complexity of the immune landscape in cancer tissues is being steadily unveiled with a progressive better understanding of the plethora of actors playing in such a scenario, resulting in histopathology diversification, distinct molecular subtypes, and biological heterogeneity. Actually, it is widely recognized that the intracellular patterns of alterations in driver genes and loci may also concur to interfere with the homeostasis of the tumor microenvironment components, deeply affecting the immune response against the tumor. Among others, the different events linked to genetic instability—aneuploidy/somatic copy number alteration (SCNA) or microsatellite instability (MSI)—may exhibit opposite behaviors in terms of immune exclusion or responsiveness. In this review, we focused on both prevalence and impact of such different types of genetic instability in melanoma in order to evaluate whether their use as biomarkers in an integrated analysis of the molecular profile of such a malignancy may allow defining any potential predictive value for response/resistance to immunotherapy.

Combining anti-cytotoxic T-lymphocyte antigen 4 (CTLA-4) and -programmed cell death protein 1 (PD-1) agents for cancer immunotherapy

Introduction: Cytotoxic T-lymphocyte antigen 4 (CTLA-4) and programmed cell death protein 1 (PD-1) represent inhibitory immune checkpoints. Combination immune checkpoint inhibitor (ICI) therapy with anti-CTLA-4 plus anti-PD-1 antibodies in preclinical models demonstrated greater anti-tumor effect than therapy with either antibody alone. Based upon this anti-tumor effect, anti-CTLA-4 plus anti-PD-1 antibodies have since been tested in a patients, across tumor types, with advanced malignancies.Areas covered: Herein we describe the biologic rationale for combining anti-CTLA-4 plus anti-PD-1 antibodies, the early studies which established different treatment schedules of the ICI combination in melanoma, the definitive studies which established the role for anti-CTLA-4 plus anti-PD-1 antibodies in patients with advanced malignancies and the toxicity profiles of these agents. We also discuss several experimental disease settings where combined CTLA-4 and PD-1 blockade is being explored.Expert opinion: We anticipate that combination therapy with anti-CTLA-4 plus anti-PD-1 antibodies will become a treatment standard for patients with cancers both responsive and unresponsive to single agent ICI therapy. Given the toxicity profile, we expect that most patients will be treated with lower doses of anti-CTLA-4 and full doses of anti-PD-1 antibodies, however, there may be instances in which a higher dose of anti-CTLA-4 is preferred.

Immune Checkpoint Inhibition as a Strategy in the Neoadjuvant Treatment of Locally Advanced Rectal Cancer

The treatment of locally advanced rectal cancer (LARC) has seen major advances over the past 3 decades, with multimodality treatment now standard of care. Combining surgical resection with radiotherapy and/or chemotherapy can reduce local recurrence from around 20% to approximately 5%. Despite improvements in local control, distant recurrence and subsequent survival rates have not changed. Immune checkpoint inhibitors have improved patient outcomes in several solid tumor types in the neoadjuvant, adjuvant, and advanced disease setting; however, in colorectal cancer, most clinical trials have been performed in the metastatic setting and the benefits confined to microsatellite instability-high tumors. In this article, we review the current preclinical and clinical evidence for using immune checkpoint inhibition in the treatment of LARC and discuss the rationale for specifically exploring the use of this therapy in the neoadjuvant setting. We summarize and discuss relevant clinical trials that are currently in setup and recruiting to test this treatment strategy and reflect on unanswered questions that still need to be addressed within future research efforts.

Checkpoint Inhibitor-Induced Colitis-A Clinical Overview of Incidence, Prognostic Implications and Extension of Current Treatment Options

In recent years, anti-tumor immunotherapies have witnessed a major breakthrough with the emergence of immune checkpoint inhibitors (ICIs). However, the use of ICIs has also brought an era of a certain class of adverse events that differ from those of classical chemotherapies and are more reminiscent of autoimmune diseases. This article focuses exclusively on colitis as an irAE with emphasis on vulnerable patient groups, the prognostic significance of colitis, treatment, and new therapeutic approaches that may be applicable. Colitis itself is associated with a favorable oncological outcome of the underlying disease but is as well the most common irAE leading to discontinuation of therapy. Especially in vulnerable patient groups such as IBD patients and elderly patients, colitis occurs more frequently as a side effect. It is precisely in these two patient groups that side effects more often lead to discontinuation of therapy. Therefore, in addition to the current therapy of colitis through immunosuppression, the focus should also be on new forms of therapy of severe colitis, such as fecal transplantation or ileostomy creation.

Efficacy and side effects of immune checkpoint inhibitors in the treatment of colorectal cancer

Colorectal cancers (CRCs) remain one of the most common and challenging neoplasia in the Western world. The response rate of immunotherapeutic treatment approaches in a subset of advanced CRCs is remarkable and has sustainably changed treatment regimens. Unfortunately, currently available immunotherapeutics only displayed significant antitumoral activity - in terms of progression free survival (PFS) and objective response rate (ORR) - in microsatellite instability-high (MSI-H)/DNA mismatch repair deficient (dMMR) CRCs. Subsequently, these remarkable results had led to the US Food and Drug Administration's approval of both immune checkpoint inhibitors (ICIs) pembrolizumab and nivolumab in the treatment of advanced MSI-H/dMMR CRCs. However, in microsatellite stable (MSS)/DNA mismatch repair proficient (pMMR) CRCs, ICIs have clearly failed to meet their expectations and are therefore not considered effective. As the vast majority of CRCs display a molecular MSS/pMMR profile, current treatment approaches endeavor to improve tumor immunogenicity that consecutively leads to increased proinflammatory cytokine levels as well as tumor infiltrating T-cells, which in turn may be targeted by various immunotherapeutic agents. Therefore, ongoing studies are investigating novel synergistic therapy modalities and approaches to overcome a "cold" to "hot" tumor conversion in MSS/pMMR CRCs. In this review, we summarize the efficacy and possible immune-related adverse events as well as novel therapeutic approaches of ICIs in the treatment of MSI-H/dMMR and MSS/pMMR CRCs.

TOX Acts as a Tumor Suppressor by Inhibiting mTOR Signaling in Colorectal Cancer

The treatment and prognosis of advanced colorectal cancer (CRC) remain a challenging clinical research focus. Here, we describe a new CRC tumor suppressor and potential therapeutic target: thymocyte selection associated high mobility group box (TOX) protein. The expression of TOX was lower in CRC than para-CRC. With the increase of tumor stage, TOX expression decreased, indicating the presence of TOX relates to better overall survival (OS). TOX suppressed the mechanistic target of rapamycin kinase (mTOR) signaling to inhibit cell proliferation, migration, invasion, and change the epithelial-mesenchymal transition (EMT) process. In addition, TOX promoted apoptosis. As tumor mutation burden and tumor microenvironment play vital roles in the occurrence and development of tumors, we analyzed the TOX expression in the immune microenvironment of CRC. The high TOX expression was negatively correlated with TumorPurity. Moreover, it was positively related to ImmuneScore, StromalScore, microsatellite instability (MSI) status, and Consensus Molecular Subtypes (CMS) 3 typing. Based on gene set enrichment analysis (GSEA), the reduced expression of TOX activated mTOR. We found rapamycin, a mTOR inhibitor, partly inhibited cell proliferation, invasion, and migration in shTOX HCT116 cells. Lastly, TOX suppressed tumorigenesis and lung metastasis of CRC in vivo. Rapamycin alone or combined with PD1 inhibitor is more effective than PD1 inhibitor alone in a tumor model. Taken together, these findings highlight the tumor-suppressive role of TOX in CRC, especially in MSI CRC, and provide valuable information that rapamycin alone or combined with PD1 inhibitor has therapeutic potential in CRC.

Long Non-coding RNA LINC02474 Affects Metastasis and Apoptosis of Colorectal Cancer by Inhibiting the Expression of GZMB

Background

Colorectal cancer (CRC) is one of the most frequently diagnosed malignancies. Metastasis is the main event that impedes the therapeutic effect on CRC, and its underlying mechanisms remain largely unclear. LINC02474 is a novel long noncoding RNA (lncRNA) associated with metastasis of CRC, while little is known about how LINC02474 regulates these malignant characteristics.

Methods

Expressions of LINC02474 and granzyme B (GZMB) were assessed by quantitative real-time polymerase chain reaction (qRT-PCR) or Western blotting analysis. Cell metastasis was detected by transwell assay and metastatic nude mouse model, and apoptosis was determined by Western blotting analysis and flow cytometry. Besides, the interaction between LINC02474 and GZMB was detected by dual-luciferase reporter assays.

Results

The expression of LINC02474 was significantly up-regulated in CRC tissues. Moreover, depletion of LINC02474 damaged the metastatic abilities of CRC cells in vivo and in vitro while boosting apoptosis. Besides, up-regulation of LINC02474 could promote migration and invasion, while apoptosis was inhibited in CRC cells. Besides, down-regulation of LINC02474 promoted the expression of GZMB, and interference of GZMB could increase the metastatic abilities of CRC cells while reducing apoptosis. Furthermore, LINC02474 was related to the transcriptional repression of GZMB in CRC cells determined by the dual-luciferase reporter assay.

Conclusions

The findings revealed that a novel lncRNA, LINC02474, as an oncogene, could promote metastasis, but limit apoptosis partly by impeding GZMB expression in CRC. Besides, LINC02474 had the potential to be used as a biomarker in the prognosis of CRC.

Pilot Clinical Trial of Perioperative Durvalumab and Tremelimumab in the Treatment of Resectable Colorectal Cancer Liver Metastases

PURPOSE

Despite the prognostic importance of immune infiltrate in colorectal cancer, immunotherapy has demonstrated limited clinical activity in refractory metastatic proficient mismatch-repair (pMMR) colorectal cancer. This study explores combining anti-CTLA-4 and an anti-PD-L1 therapy in the preoperative management of resectable colorectal cancer liver metastases with the intent to improve immune responses in this disease setting.

PATIENTS AND METHODS

Patients with resectable colorectal cancer liver-only metastases received one dose of tremelimumab and durvalumab preoperatively followed by single-agent durvalumab postoperatively. Primary objectives were to determine feasibility and safety.

RESULTS

A total of 24 patients were enrolled between November 2016 and November 2019. Twenty-three patients received treatment [21 pMMR and 2 deficient mismatch-repair (dMMR)] and subsequently 17 (74%; 95% CI: 53%-88%) underwent surgical resection. Grade 3/4 treatment-related immune toxicity and postoperative grade 3/4 toxicity were seen in 5/23 (22%; 95% CI: 10%-44%) and 2/17 (12%; 95% CI: 2%-38%) patients. The median relapse-free survival (RFS) was 9.7 (95% CI: 8.1-17.8) months, and overall survival was 24.5 (95% CI: 16.5-28.4) months. Four patients demonstrated complete pathologic response, two dMMR patients and two POLE mutation patients. Pre- and post-tumor tissue analysis by flow cytometry, immunofluorescence, and RNA sequencing revealed similar levels of T-cell infiltration, but did demonstrate evidence of CD8⁺ and CD4⁺ activation posttreatment. An increase in B-cell transcriptome signature and B-cell density was present in posttreatment samples from patients with prolonged RFS.

CONCLUSIONS

This study demonstrates the safety of neoadjuvant combination tremelimumab and durvalumab prior to colorectal cancer liver resection. Evidence for T- and B-cell activation following this therapy was seen in pMMR metastatic colorectal cancer.