Ascites and resistance to immune checkpoint inhibition in dMMR/MSI-H metastatic colorectal and gastric cancers

Resiquimod-loaded cationic liposomes cure mice with peritoneal carcinomatosis and induce specific anti-tumor immunity

Peritoneal carcinomatosis (PC) is characterized by a high recurrence rate and mortality following cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (HIPEC), primarily due to incomplete cancer elimination. To enhance the standard of care for PC, we developed two cationic liposomal formulations aimed at localizing a toll-like receptor agonist, resiquimod (R848), in the peritoneal cavity to activate the immune system locally to specifically eradicate residual tumor cells. These formulations effectively extended R848 retention in the peritoneum by >10-fold, resulting in up to a 2-fold increase in interferon α (IFN-α) induction in the peritoneal fluid, without increasing the plasma levels. In a CT26 colon cancer model with peritoneal metastases, these liposomal R848 formulations, when combined with oxaliplatin (OXA)-an agent used in HIPEC that induces immunogenic cell death-increased tumor infiltration of effector immune cells, including DCs, CD4, and CD8 T cells. This led to the complete elimination of PC in 60-70% of the mice, while the control mice reached humane endpoints by 30 days. The cured mice developed specific antitumor immunity, as re-challenging them with the same tumor cells did not result in tumor establishment. However, inoculation with a different tumor line led to tumor development. Additionally, exposing CT26 tumor antigens to the splenocytes isolated from the cured mice induced the expansion of CD4 and CD8 T cells and the release of IFN-γ, demonstrating long-term immune memory to the specific tumor. The anti-tumor efficacy of these liposomal R848 formulations was mediated via CD8 T cells with different levels of involvement of CD4 and B cells, and the combination with an anti-PD-1 antibody achieved a cure rate of 90%.

Clinical and Molecular Variables Associated With Early Progression to Checkpoint Inhibitors in MSI-High Metastatic Colorectal Cancer: A Retrospective Cohort Study

BACKGROUND

About one third of patients with deficient mismatch repair/microsatellite instability-high metastatic colorectal cancer (dMMR/MSI-H mCRC) experience primary resistance or early progression on immune checkpoint inhibitors (ICI), while others benefit from exceptionally long-lasting responses. In this single-centre retrospective study, we aimed to identify variables associated with improved overall survival (OS) as well as early disease progression.

METHODS

All dMMR/MSI-H mCRC patients treated with ICI between 2014 and 2022 were included. Baseline patient demographics, tumour characteristics as well response and outcome data were recorded. OS was estimated using the Kaplan-Meier method. Uni- and multivariate cox regression analysis was used to identify parameters associated with improved OS. Clinicopathological factors associated with early progression (≤ 12 months after treatment initiation) were assessed using uni- and multivariate logistic regression analysis.

RESULTS

About 84 ICI-treated dMMR/MSI-H mCRC patients were included. Progressive disease occurred in 37 (44%) patients, but only in 11 (19%) patients with disease control at 12 months. Median OS was 80 months and improved outcome was associated with a lower neutrophile-to-lymphocyte ratio (NLR) (P = .004) and the presence of immune-related adverse events (irAEs) (P = .015). Early progression was associated with poor performance status (P = .036), a higher blood CRP level (P = .033) and absence of irAEs (P = .002).

CONCLUSION

Disease progression in ICI-treated dMMR/MSI-H mCRC rarely occurs in patients experiencing disease control for at least 12 months. Performance status, presence of immune-related adverse events, CRP levels, CEA levels and NLR can be helpful to identify those patients that may benefit from ICI treatment, guiding clinicians in therapeutic decisions.

Microsatellite Instability Detection in Cancer: A Multiplex qPCR Approach that Obviates the Need for Matching Normal Samples

BACKGROUND

Microsatellite instability (MSI) indicates DNA mismatch repair deficiency in certain types of cancer, such as colorectal cancer. The current gold standard technique, PCR-capillary electrophoresis (CE), requires matching normal samples and specialized instrumentation. We developed VarTrace, a rapid and low-cost quantitative PCR (qPCR) assay, to evaluate MSI using solely the tumor sample DNA, obviating the requirement for matching normal samples.

METHODS

One hundred and one formalin-fixed paraffin-embedded (FFPE) tumor samples were tested using VarTrace and compared with the Promega OncoMate assay utilizing PCR-CE. Tumor percentage limit of detection was evaluated on contrived samples derived from clinical high MSI (MSI-H) samples. Analytical sensitivity, specificity, limit of detection, and input requirements were assessed using synthetic commercial reference standards.

RESULTS

VarTrace successfully analyzed all 101 clinical FFPE samples, demonstrating 100% sensitivity and 98% specificity compared to OncoMate. It detected MSI-H with 97% accuracy down to 10% tumor. Analytical studies using synthetic samples showed a limit of detection of 5% variant allele frequency and a limit of input of 0.5 ng.

CONCLUSIONS

This study validates VarTrace as a swift, accurate, and economical assay for MSI detection in samples with low tumor percentages without the need for matching normal DNA. VarTrace's capacity for highly sensitive MSI analysis holds potential for enhancing the efficiency of clinical work flows and broadening the availability of this test.

Management of Microsatellite Instability High (MSI-H) Gastroesophageal Adenocarcinoma

BACKGROUND

Gastroesophageal cancer is a major cause of cancer-related mortality worldwide. Treatment of both early stage and advanced disease remains highly reliant on cytotoxic chemotherapy. About 4-24% of gastroesophageal cancers are microsatellite instability high (MSI-H). The MSI-H subtype is associated with favorable prognosis, resistance to cytotoxic chemotherapy, and sensitivity to immune checkpoint inhibitors (ICI). Recent studies have demonstrated promising activity of ICIs in the MSI-H subtype, resulting in fundamental changes in the management of MSI-H gastroesophageal adenocarcinoma.

PURPOSE

In this review, we discuss the prevalence, characteristics, prognosis, and management of MSI-H gastroesophageal adenocarcinoma, with a focus on recent and ongoing studies that have changed the landscape of treatment for the MSI-H subtype. We also discuss current challenges in the management of resectable and advanced MSI-H gastroesophageal cancer, including the need for more accurate biomarkers of response to ICI therapy.

Current and Future Trends of Colorectal Cancer Treatment: Exploring Advances in Immunotherapy

Cancer of the colon and rectum (CRC) has been identified among the three most prevalent types of cancer and cancer-related deaths for both sexes. Even though significant progress in surgical and chemotherapeutic techniques has markedly improved disease-free and overall survival rates in contrast to those three decades ago, recent years have seen a stagnation in these improvements. This underscores the need for new therapies aiming to augment patient outcomes. A number of emerging strategies, such as immune checkpoint inhibitors (ICIs) and adoptive cell therapy (ACT), have exhibited promising outcomes not only in preclinical but also in clinical settings. Additionally, a thorough appreciation of the underlying biology has expanded the scope of research into potential therapeutic interventions. For instance, the pivotal role of altered telomere length in early CRC carcinogenesis, leading to chromosomal instability and telomere dysfunction, presents a promising avenue for future treatments. Thus, this review explores the advancements in CRC immunotherapy and telomere-targeted therapies, examining potential synergies and how these novel treatment modalities intersect to potentially enhance each other's efficacy, paving the way for promising future therapeutic advancements.

Specific lineage transition of tumor-associated macrophages elicits immune evasion of ascitic tumor cells in gastric cancer with peritoneal metastasis

BACKGROUND

Gastric cancer with peritoneal metastasis (PM-GC), recognized as one of the deadliest cancers. However, whether and how the tumor cell-extrinsic tumor microenvironment (TME) is involved in the therapeutic failure remains unknown. Thus, this study systematically assessed the immunosuppressive tumor microenvironment in ascites from patients with PM-GC, and its contribution to dissemination and immune evasion of ascites-disseminated tumor cells (aDTCs).

METHODS

Sixty-three ascites and 43 peripheral blood (PB) samples from 51 patients with PM-GC were included in this study. aDTCs in ascites and circulating tumor cells (CTCs) in paired PB were immunophenotypically profiled. Using single-cell RNA transcriptional sequencing (scRNA-seq), crosstalk between aDTCs and the TME features of ascites was inspected. Further studies on the mechanism underlying aDTCs-immune cells crosstalk were performed on in vitro cultured aDTCs.

RESULTS

Immune cells in ascites interact with aDTCs, prompting their immune evasion. Specifically, we found that the tumor-associated macrophages (TAMs) in ascites underwent a continuum lineage transition from cathepsinhigh (CTShigh) to complement 1qhigh (C1Qhigh) TAM. CTShigh TAM initially attracted the metastatic tumor cells to ascites, thereafter, transitioning terminally to C1Qhigh TAM to trigger overproliferation and immune escape of aDTCs. Mechanistically, we demonstrated that C1Qhigh TAMs significantly enhanced the expression of PD-L1 and NECTIN2 on aDTCs, which was driven by the activation of the C1q-mediated complement pathway.

CONCLUSIONS

For the first time, we identified an immunosuppressive macrophage transition from CTShigh to C1Qhigh TAM in ascites from patients with PM-GC. This may contribute to developing potential TAM-targeted immunotherapies for PM-GC.

Discovery of WRN inhibitor HRO761 with synthetic lethality in MSI cancers

The Werner syndrome RecQ helicase WRN was identified as a synthetic lethal target in cancer cells with microsatellite instability (MSI) by several genetic screens1-6. Despite advances in treatment with immune checkpoint inhibitors7-10, there is an unmet need in the treatment of MSI cancers11-14. Here we report the structural, biochemical, cellular and pharmacological characterization of the clinical-stage WRN helicase inhibitor HRO761, which was identified through an innovative hit-finding and lead-optimization strategy. HRO761 is a potent, selective, allosteric WRN inhibitor that binds at the interface of the D1 and D2 helicase domains, locking WRN in an inactive conformation. Pharmacological inhibition by HRO761 recapitulated the phenotype observed by WRN genetic suppression, leading to DNA damage and inhibition of tumour cell growth selectively in MSI cells in a p53-independent manner. Moreover, HRO761 led to WRN degradation in MSI cells but not in microsatellite-stable cells. Oral treatment with HRO761 resulted in dose-dependent in vivo DNA damage induction and tumour growth inhibition in MSI cell- and patient-derived xenograft models. These findings represent preclinical pharmacological validation of WRN as a therapeutic target in MSI cancers. A clinical trial with HRO761 (NCT05838768) is ongoing to assess the safety, tolerability and preliminary anti-tumour activity in patients with MSI colorectal cancer and other MSI solid tumours.

Chemoproteomic discovery of a covalent allosteric inhibitor of WRN helicase

WRN helicase is a promising target for treatment of cancers with microsatellite instability (MSI) due to its essential role in resolving deleterious non-canonical DNA structures that accumulate in cells with faulty mismatch repair mechanisms1-5. Currently there are no approved drugs directly targeting human DNA or RNA helicases, in part owing to the challenging nature of developing potent and selective compounds to this class of proteins. Here we describe the chemoproteomics-enabled discovery of a clinical-stage, covalent allosteric inhibitor of WRN, VVD-133214. This compound selectively engages a cysteine (C727) located in a region of the helicase domain subject to interdomain movement during DNA unwinding. VVD-133214 binds WRN protein cooperatively with nucleotide and stabilizes compact conformations lacking the dynamic flexibility necessary for proper helicase function, resulting in widespread double-stranded DNA breaks, nuclear swelling and cell death in MSI-high (MSI-H), but not in microsatellite-stable, cells. The compound was well tolerated in mice and led to robust tumour regression in multiple MSI-H colorectal cancer cell lines and patient-derived xenograft models. Our work shows an allosteric approach for inhibition of WRN function that circumvents competition from an endogenous ATP cofactor in cancer cells, and designates VVD-133214 as a promising drug candidate for patients with MSI-H cancers.

A multicenter study evaluating efficacy of immune checkpoint inhibitors in advanced non-colorectal digestive cancers with microsatellite instability

BACKGROUND

One randomized phase III trial comparing chemotherapy (CT) with immune checkpoint inhibitors (ICI) has demonstrated significant efficacy of ICI in deficient DNA mismatch repair system/microsatellite instability-high (dMMR/MSI-H) metastatic colorectal cancer. However, few studies have compared ICI with CT in other advanced dMMR/MSI-H digestive tumors.

METHODS

In this multicenter study, we included patients with advanced dMMR/MSI-H non-colorectal digestive tumors treated with chemotherapy and/or ICIs. Patients were divided retrospectively into two groups, a CT group and an immunotherapy (IO) group. The primary endpoint was progression-free survival (PFS). A propensity score approach using the inverse probability of treatment weighting (IPTW) method was applied to deal with potential differences between the two groups.

RESULTS

133 patients (45.1/27.1/27.8% with gastric/small bowel/other carcinomas) were included. The majority of patients received ICI in 1st (29.1%) or 2nd line (44.4%). The 24-month PFS rates were 7.9% in the CT group and 71.2% in the IO group. Using the IPTW method, IO treatment was associated with better PFS (HR=0.227; 95% CI 0.147-0.351; p < 0.0001). The overall response rate was 26.3% in the CT group versus 60.7% in the IO group (p < 0.001) with prolonged duration of disease control in the IO group (p < 0.001). In multivariable analysis, predictive factors of PFS for patients treated with IO were good performance status, absence of liver metastasis and prior primary tumor resection, whereas no association was found for the site of the primary tumor.

CONCLUSIONS

In the absence of randomized trials, our study highlights the superior efficacy of ICI compared with standard-of-care therapy in patients with unresectable or metastatic dMMR/MSI-H non-colorectal digestive cancer, regardless of tumor type, with acceptable toxicity.

Primary resistance to immunotherapy in patients with a dMMR/MSI metastatic gastrointestinal cancer: who is at risk? An AGEO real-world study

BACKGROUND

The outstanding efficacy of immunotherapy in metastatic dMMR/MSI gastro-intestinal (GI) cancers has led to a rapid increase in the number of patients treated. However, 20-30% of patients experience primary resistance to immune checkpoint inhibitors (ICIPR) and need better characterization.

METHODS

This AGEO real-world study retrospectively analyzed the efficacy and safety of ICIs and identified clinical variables associated with ICIPR in patients with metastatic dMMR/MSI GI cancers treated with immunotherapy between 2015 and 2022.

RESULTS

399 patients were included, 284 with colorectal cancer (CRC) and 115 with non-CRC, mostly treated by an anti-PD(L)1 (88.0%). PFS at 24 months was 55.8% (95CI [50.8-61.2]) and OS at 48 months was 59.1% (95CI [53.0-65.9]). ORR was 51.0%, and 25.1% of patients were ICIPR. There was no statistical difference in ORR, DCR, PFS, or OS between CRC and non-CRC groups. In multivariable analysis, ICIPR was associated with ECOG-PS ≥ 2 (OR = 3.36), liver metastases (OR = 2.19), peritoneal metastases (OR = 2.00), ≥1 previous line of treatment (OR = 1.83), and age≤50 years old (OR = 1.76).

CONCLUSION

These five clinical factors associated with primary resistance to ICIs should be considered by physicians to guide treatment choice in GI dMMR/MSI metastatic cancer patients.

The Efficacy and Safety of Nivolumab Plus mFOLFOX6 in Gastric Cancer with Severe Peritoneal Metastasis

(1) Background: Nivolumab plus chemotherapy is established as a first-line treatment for advanced gastric cancer (AGC). While mFOLFOX6 is commonly used for AGC with severe peritoneal metastasis, the efficacy of nivolumab combined with it remains uncertain. We evaluated the outcomes of nivolumab plus mFOLFOX6 for AGC with severe peritoneal metastasis in clinical practice. (2) Methods: This multicenter retrospective study was conducted between December 2021 and June 2023. We investigated AGC patients with massive ascites or inadequate oral intake due to severe peritoneal metastasis and who received nivolumab plus mFOLFOX6. (3) Results: Among 106 patients treated with nivolumab plus chemotherapy, 21 (19.8%) had severe peritoneal metastasis, with 14 receiving nivolumab plus mFOLFOX6. The median progression-free survival was 7.4 months (95%CI 1.9-10.1), and the median overall survival was 10.7 months (95%CI 5.3-NA), with four patients (28.5%) surviving more than 12 months. Improved ascites and oral intake were observed in 6/14 patients (42.8%) and 10/11 patients (90.9%), respectively. The major grade 3 or more adverse events included leukopenia (28.5%) and neutropenia (21.4%), with no severe immune-related adverse events reported. (4) Conclusions: The safety and moderate efficacy of nivolumab plus mFOLFOX6 were suggested even in AGC patients with severe peritoneal metastasis.

Deficient mismatch repair/microsatellite unstable colorectal cancer: therapeutic advances and questions

The microsatellite instability (MSI) phenotype is related to a deficiency of the DNA mismatch repair (dMMR) system and is observed in 5% of metastatic colorectal cancers (mCRCs). MSI/dMMR phenotype testing should be routine for all CRCs regardless of stage. Two complementary techniques with a high concordance (90-97%) allow us to determine the MSI/dMMR status of a tumor: immunohistochemistry and polymerase chain reaction. Since 2020 and the results of the phase III KEYNOTE 177 trial, pembrolizumab [anti-programmed cell death protein 1 (PD1)] is the new standard of care in first-line MSI/dMMR mCRC. To date, no combination of chemtotherapy ± targeted therapy with immune checkpoint inhibitors (ICIs) has been validated in the management of MSI/dMMR mCRC, and it is not known whether this combination would be beneficial. It is also unclear whether dual therapy with two ICIs is more effective than monotherapy. Several phase III trials are ongoing to answer these questions. Despite a high response rate and long-term benefit of a first line by anti-PD1, 30-50% of patients with MSI/dMMR mCRC experience an early or secondary progression. There are currently no validated predictive biomarkers of anti-PD1 ± anti-cytotoxic T lymphocyte antigen-4 resistance in patients with MSI/dMMR mCRC. In case of early progression on ICIs, the first two questions to consider are the possibility of pseudoprogression and the correct diagnosis of MSI/dMMR status. To date, there are no data on the use of adjuvant ICIs for MSI/dMMR resected colon cancers. By contrast, data are accumulating regarding the efficacy of neoadjuvant ICIs, with at least two-thirds of patients in the different trials in pathological complete response, making it possible to envisage 'Watch and wait' strategies in future.

Immune checkpoints signature-based risk stratification for prognosis of patients with gastric cancer

Until now, few researches have comprehensive explored the role of immune checkpoints (ICIs) and tumor microenvironment (TME) in gastric cancer (GC) patients based on the genomic data. RNA-sequence data and clinical information were obtained from The Cancer Genome Atlas Stomach Adenocarcinoma (TCGA-STAD) database, GSE84437 and GSE84433. Univariate Cox analysis identified 60 ICIs with prognostic values, and these genes were then subjected to NMF cluster analysis and the GC samples (n = 804) were classified into two distinct subtypes (Cluster 1: n = 583; Cluster 2: n = 221). The Kaplan-Meier curves for OS analysis indicated that C1 predicted a poorer prognosis. The C2 subtype illustrated a relatively better prognosis and characteristics of "hot tumors," including high immune score, overexpression of immune checkpoint molecules, and enriched tumor-infiltrated immune cells, indicating that the NMF clustering in GC was robust and stable. Regarding the patient's heterogeneity, an ICI-score was constructed to quantify the ICI patterns in individual patients. Moreover, the study found that the low ICI-score group contained mostly MSI-low events, and the high ICI-score group contained predominantly MSI-high events. In addition, the ICI-score groups had good responsiveness to CTLA4 and PD-1 based on The Cancer Immunome Atlas (TCIA) database. Our research firstly constructed ICIs signature, as well as identified some hub genes in GC patients.

Biomarkers and experimental models for cancer immunology investigation

The rapid advancement of tumor immunotherapies poses challenges for the tools used in cancer immunology research, highlighting the need for highly effective biomarkers and reproducible experimental models. Current immunotherapy biomarkers encompass surface protein markers such as PD-L1, genetic features such as microsatellite instability, tumor-infiltrating lymphocytes, and biomarkers in liquid biopsy such as circulating tumor DNAs. Experimental models, ranging from 3D in vitro cultures (spheroids, submerged models, air-liquid interface models, organ-on-a-chips) to advanced 3D bioprinting techniques, have emerged as valuable platforms for cancer immunology investigations and immunotherapy biomarker research. By preserving native immune components or coculturing with exogenous immune cells, these models replicate the tumor microenvironment in vitro. Animal models like syngeneic models, genetically engineered models, and patient-derived xenografts provide opportunities to study in vivo tumor-immune interactions. Humanized animal models further enable the simulation of the human-specific tumor microenvironment. Here, we provide a comprehensive overview of the advantages, limitations, and prospects of different biomarkers and experimental models, specifically focusing on the role of biomarkers in predicting immunotherapy outcomes and the ability of experimental models to replicate the tumor microenvironment. By integrating cutting-edge biomarkers and experimental models, this review serves as a valuable resource for accessing the forefront of cancer immunology investigation.

Patient-derived exosomes facilitate therapeutic targeting of oncogenic MET in advanced gastric cancer

Gastric cancer (GC) with peritoneal metastases and malignant ascites continues to have poor prognosis. Exosomes mediate intercellular communication during cancer progression and promote therapeutic resistance. Here, we report the significance of exosomes derived from malignant ascites (EXOAscites) in cancer progression and use modified exosomes as resources for cancer therapy. EXOAscites from patients with GC stimulated invasiveness and angiogenesis in an ex vivo three-dimensional autologous tumor spheroid microfluidic system. EXOAscites concentration increased invasiveness, and blockade of their secretion suppressed tumor progression. In MET-amplified GC, EXOAscites contain abundant MET; their selective delivery to tumor cells enhanced angiogenesis and invasiveness. Exosomal MET depletion substantially reduced invasiveness; an additive therapeutic effect was induced when combined with MET and/or VEGFR2 inhibition in a patient-derived MET-amplified GC model. Allogeneic MET-harboring exosome delivery induced invasion and angiogenesis in a MET non-amplified GC model. MET-amplified patient tissues showed higher exosome concentration than their adjacent normal tissues. Manipulating exosome content and production may be a promising complementary strategy against GC.

Of mice and lymphoid aggregates: modeling tertiary lymphoid structures in cancer

Tertiary lymphoid structures (TLS) are lymph node-like aggregates that can form in association with chronic inflammation or cancer. Mature TLS are organized into B and T cell zones, and are not encapsulated but include all cell types necessary for eliciting an adaptive immune response. TLS have been observed in various cancer types and are generally associated with a positive prognosis as well as increased sensitivity to cancer immunotherapy. However, a comprehensive understanding of the roles of TLS in eliciting anti-tumor immunity as well as the mechanisms involved in their formation and function is still lacking. Further studies in orthotopic, immunocompetent cancer models are necessary to evaluate the influence of TLS on cancer therapies, and to develop new treatments that promote their formation in cancer. Here, we review key insights obtained from functional murine studies, discuss appropriate models that can be used to study cancer-associated TLS, and suggest guidelines on how to identify TLS and distinguish them from other antigen-presenting niches.

Tumor-agnostic drug development in dMMR/MSI-H solid tumors

Mismatch repair deficiency (dMMR) or microsatellite instability-high (MSI-H) represents a distinct phenotype among solid tumors characterized by frequent frameshift mutations resulting in the generation of neoantigens that are highly immunogenic. Seminal studies identified that dMMR/MSI-H tumors are exquisitely sensitive to immune checkpoint inhibitors, which has dramatically improved outcomes for patients harboring dMMR/MSI-H tumors. Nevertheless, many patients develop resistance to single-agent immune checkpoint blockade, prompting the need for improved therapeutic options for this patient population. In this review, we highlight key studies examining the efficacy of PD1 inhibitors in the metastatic and neoadjuvant setting for patients with dMMR/MSI-H tumors, describe resistance mechanisms to immune checkpoint blockade, and discuss novel treatment approaches that are currently under investigation for dMMR/MSI-H tumors.

Avelumab vs Standard Second-Line Chemotherapy in Patients With Metastatic Colorectal Cancer and Microsatellite Instability: A Randomized Clinical Trial

Importance

Only 1 randomized clinical trial has shown the superiority of immune checkpoint inhibitors in patients with deficient mismatch repair and/or microsatellite instability (dMMR/MSI) metastatic colorectal cancer (mCRC) in the first-line setting.

Objectives

To determine whether avelumab (an anti-programmed cell death ligand 1 antibody) improves progression-free survival (PFS) compared with standard second-line chemotherapy in patients with dMMR/MSI mCRC.

Design, Setting, and Participants

The SAMCO-PRODIGE 54 trial is a national open-label phase 2 randomized clinical trial that was conducted from April 24, 2018, to April 29, 2021, at 49 French sites. Patients with dMMR/MSI mCRC who experienced progression while receiving standard first-line therapy were included in the analysis.

Interventions

Patients were randomized to receive standard second-line therapy or avelumab every 2 weeks until progression, unacceptable toxic effects, or patient refusal.

Main Outcome and Measures

The primary end point was PFS according to RECIST (Response Evaluation Criteria in Solid Tumours), version 1.1, evaluated by investigators in patients with mCRC and confirmed dMMR and MSI status who received at least 1 dose of treatment (modified intention-to-treat [mITT] population).

Results

A total of 122 patients were enrolled in the mITT population. Median age was 66 (IQR, 56-76) years, 65 patients (53.3%) were women, 100 (82.0%) had a right-sided tumor, and 52 (42.6%) had BRAF V600E-mutated tumors. There was no difference in patients and tumor characteristics between treatment groups. No new safety concerns in either group were detected, with fewer treatment-related adverse events of at least grade 3 in the avelumab group than in the chemotherapy group (20 [31.7%] vs 34 [53.1%]; P = .02). After a median follow-up of 33.3 (95% CI, 28.3-34.8) months, avelumab was superior to chemotherapy with or without targeted agents with respect to PFS (15 [24.6%] vs 5 [8.2%] among patients without progression; P = .03). Rates of PFS rates at 12 months were 31.2% (95% CI, 20.1%-42.9%) and 19.4% (95% CI, 10.6%-30.2%) in the avelumab and control groups, respectively, and 27.4% (95% CI, 16.8%-39.0%) and 9.1% (95% CI, 3.2%-18.8%) at 18 months. Objective response rates were similar in both groups (18 [29.5%] vs 16 [26.2%]; P = .45). Among patients with disease control, 18 (75.7%) in the avelumab group compared with 9 (19.1%) in the control group had ongoing disease control at 18 months.

Conclusions

The SAMCO-PRODIGE 54 phase 2 randomized clinical trial showed, in patients with dMMR/MSI mCRC, better PFS and disease control duration with avelumab over standard second-line treatment, with a favorable safety profile.

Trial Registration

ClinicalTrials.gov Identifier: NCT03186326.

Effect of liver metastasis on the efficacy of immune checkpoint inhibitors in cancer patients: a systemic review and meta-analysis

Liver metastasis is a frequent phenomenon in advanced tumor disease. Immune checkpoint inhibitors (ICIs) are a new class of therapeutics that can improve the prognosis of cancer patients. The purpose of this study is to elucidate the relationship between liver metastasis and survival outcomes of patients receiving ICIs treatment. We searched four main databases, including PubMed, EMBASE, Cochrane Library, and Web of Science. Overall survival (OS) and progression-free survival (PFS) were the survival outcomes of our concern. Hazard ratio (HR) with 95% confidence interval (CI) were used to evaluate the relationship between liver metastasis and OS/ PFS. Finally, 163 articles were included in the study. The pooled results showed that patients with liver metastasis receiving ICIs treatment had worse OS (HR=1.82, 95%CI:1.59-2.08) and PFS (HR=1.68, 95%CI:1.49-1.89) than patients without liver metastasis. The effect of liver metastasis on ICIs efficacy differed in different tumor types, and patients with urinary system tumors (renal cell carcinoma OS: HR=2.47, 95%CI:1.76-3.45; urothelial carcinoma OS: HR=2.37, 95%CI:2.03-2.76) had the worst prognosis, followed by patients with melanoma (OS: HR=2.04, 95%CI:1.68-2.49) or non-small cell lung cancer (OS: HR=1.81, 95%CI:1.72-1.91). ICIs efficacy in digestive system tumors (colorectal cancer OS: HR=1.35, 95%CI:1.07-1.71; gastric cancer/ esophagogastric cancer OS: HR=1.17, 95%CI:0.90-1.52) was less affected, and peritoneal metastasis and the number of metastases have a greater clinical significance than liver metastasis based on univariate data. For cancer patients receiving ICIs treatment, the occurrence of liver metastasis is associated with poor prognosis. Different cancer types and metastatic sites may hold a different prognostic effect on the efficacy of ICIs treatment in cancer patients.

Tumour mutational burden as a biomarker in patients with mismatch repair deficient/microsatellite instability-high metastatic colorectal cancer treated with immune checkpoint inhibitors

BACKGROUND

Immune checkpoint inhibitors (ICIs) are the standard treatment in patients with mismatch repair deficient (dMMR)/microsatellite instability-high (MSI-H) metastatic colorectal cancer (mCRC). Tumour mutational burden (TMB) is a promising biomarker for the prediction of treatment outcomes.

PATIENTS AND METHODS

We screened 203 patients with dMMR/MSI-H mCRC treated with an anti-PD-(L)1 (anti-Programmed-Death-(Ligand)1) plus or minus an anti-Cytotoxic T-Lymphocyte Antigen 4 (anti-CTLA-4) agent at three Italian Academic Centers. TMB was tested by Foundation One Next Generation Sequencing assay and correlated with clinical outcomes, in the overall population and according to ICI regimen.

RESULTS

We included 110 patients with dMMR/MSI-H mCRC. Eighty patients received anti-PD-(L)1 monotherapy and 30 received anti-CTLA-4 combinations. Median TMB was 49 mut/Mb (range: 8-251 mut/Mb). The optimal prognostic cut-off for progression-free survival (PFS) stratification was 23 mut/Mb. Patients with TMB ≤23 mut/Mb had significantly worse PFS (adjusted Hazard Ratio [aHR] = 4.26, 95% confidence interval [CI]:1.85-9.82, p = 0.001) and overall survival (OS) (aHR = 5.14, 95% CI: 1.76-14.98, p = 0.003). Using a cut-off optimised for predicting treatment outcome, anti-CTLA-4 combination was associated with a significant PFS/OS benefit versus anti-PD-(L)1 monotherapy in patients with TMB>40 mut/Mb (2-year PFS: 100.0% versus 70.7%, p = 0.002; 2-year OS: 100.0% versus 76.0%, p = 0.025), but not in those with TMB ≤40 mut/Mb (2-year PFS: 59.7% versus 68.6%, p = 0.888; 2-year OS: 80.0% versus 81.0%, p = 0.949).

CONCLUSION

Patients with dMMR/MSI-H mCRC and relatively lower TMB value displayed early disease progression when receiving ICIs, whereas patients with the highest TMB values may obtain the maximal benefit from intensified anti-CTLA-4/PD-1 combination.

Outcomes and a prognostic classifier in patients with microsatellite instability-high metastatic gastric cancer receiving PD-1 blockade

BACKGROUND

Subgroup analyses of randomized trials suggest the superiority of immune checkpoint inhibitor-based therapy over chemotherapy in patients with mismatch-repair deficient (dMMR) and/or microsatellite instability-high (MSI-high) advanced gastric or gastroesophageal junction adenocarcinoma. However, these subgroups are small and studies examining prognostic features within dMMR/MSI-high patients are lacking.

METHODS

We conducted an international cohort study at tertiary cancer centers and collected baseline clinicopathologic features of patients with dMMR/MSI-high metastatic or unresectable gastric cancer treated with anti-programmed cell death protein-1 (PD-1)-based therapies. The adjusted HRs of variables significantly associated with overall survival (OS) were used to develop a prognostic score.

RESULTS

One hundred and thirty patients were included. At a median follow-up of 25.1 months, the median progression-free survival (PFS) was 30.3 months (95% CI: 20.4 to NA) and 2-year PFS rate was 56% (95% CI: 48% to 66%). Median OS was of 62.5 months (95% CI: 28.4 to NA) and 2-year OS rate was 63% (95% CI: 55% to 73%). Among the 103 Response Evaluation Criteria in Solid Tumors-evaluable patients, objective response rate was 66% and disease control rate 87% across lines of therapy. In the multivariable models, Eastern Cooperative Oncology Group Performance Status of 1 or 2, non-resected primary tumor, presence of bone metastases and malignant ascites were independently associated with poorer PFS and OS. These four clinical variables were used to build a three-category (ie, good, intermediate, and poor risk) prognostic score. Compared with patients with good risk, patients with intermediate risk score had numerically inferior PFS and OS (2-year PFS rate: 54.3% versus 74.5%, HR 1.90, 95% CI: 0.99 to 3.66; 2-year OS rate: 66.8% versus 81.2%, HR 1.86, 95% CI: 0.87 to 3.98), whereas patients with poor risk score had significantly inferior PFS and OS (2-year PFS rate: 10.6%, HR 9.65, 95% CI: 4.67 to 19.92; 2-year OS rate: 13.3%, HR 11.93, 95% CI: 5.42 to 26.23).

CONCLUSIONS

Overall outcomes with anti-PD-1-based therapies are favorable in MSI-high gastroesophageal adenocarcinomas. However, within this overall favorable subgroup a more accurate prognostication using baseline clinical characteristics might identify patients at higher risk of rapid disease progression who may deserve intensified immunotherapy combination strategies.

Society for Immunotherapy of Cancer (SITC) clinical practice guideline on immunotherapy for the treatment of gynecologic cancer

Advanced gynecologic cancers have historically lacked effective treatment options. Recently, immune checkpoint inhibitors (ICIs) have been approved by the US Food and Drug Administration for the treatment of cervical cancer and endometrial cancer, offering durable responses for some patients. In addition, many immunotherapy strategies are under investigation for the treatment of earlier stages of disease or in other gynecologic cancers, such as ovarian cancer and rare gynecologic tumors. While the integration of ICIs into the standard of care has improved outcomes for patients, their use requires a nuanced understanding of biomarker testing, treatment selection, patient selection, response evaluation and surveillance, and patient quality of life considerations, among other topics. To address this need for guidance, the Society for Immunotherapy of Cancer (SITC) convened a multidisciplinary panel of experts to develop a clinical practice guideline. The Expert Panel drew on the published literature as well as their own clinical experience to develop evidence- and consensus-based recommendations to provide guidance to cancer care professionals treating patients with gynecologic cancer.

Co-cultures of colon cancer cells and cancer-associated fibroblasts recapitulate the aggressive features of mesenchymal-like colon cancer

Background

Poor prognosis in colon cancer is associated with a high content of cancer-associated fibroblasts (CAFs) and an immunosuppressive tumor microenvironment. The relationship between these two features is incompletely understood. Here, we aimed to generate a model system for studying the interaction between cancer cells and CAFs and their effect on immune-related cytokines and T cell proliferation.

Methods

CAFs were isolated from colon cancer liver metastases and were immortalized to prolong lifespan and improve robustness and reproducibility. Established medium and matrix compositions that support the growth of patient-derived organoids were adapted to also support CAF growth. Changes in growth pattern and cellular re-organization were assessed by confocal microscopy, live cell imaging, and immunofluorescence. Single cell RNA sequencing was used to study CAF/organoid co-culture-induced phenotypic changes in both cell types. Conditioned media were used to quantify the production of immunosuppressive factors and to assess their effect on T cell proliferation.

Results

We developed a co-culture system in which colon cancer organoids and CAFs spontaneously organize into superstructures with a high capacity to contract and stiffen the extracellular matrix (ECM). CAF-produced collagen IV provided a basement membrane supporting cancer cell organization into glandular structures, reminiscent of human cancer histology. Single cell RNA sequencing analysis showed that CAFs induced a partial epithelial-to-mesenchymal-transition in a subpopulation of cancer cells, similar to what is observed in the mesenchymal-like consensus molecular subtype 4 (CMS4) colon cancer. CAFs in co-culture were characterized by high expression of ECM components, ECM-remodeling enzymes, glycolysis, hypoxia, and genes involved in immunosuppression. An expression signature derived from CAFs in co-culture identified a subpopulation of glycolytic myofibroblasts specifically residing in CMS1 and CMS4 colon cancer. Medium conditioned by co-cultures contained high levels of the immunosuppressive factors TGFβ1, VEGFA and lactate, and potently inhibited T cell proliferation.

Conclusion

Co-cultures of organoids and immortalized CAFs recapitulate the histological, biophysical, and immunosuppressive features of aggressive mesenchymal-like human CRC. The model can be used to study the mechanisms of immunosuppression and to test therapeutic strategies targeting the cross-talk between CAFs and cancer cells. It can be further modified to represent distinct colon cancer subtypes and (organ-specific) microenvironments.

Immunotherapy for Peritoneal Carcinomatosis: Challenges and Prospective Outcomes

Peritoneal metastasis, also known as peritoneal carcinomatosis (PC), is a refractory cancer that is typically resistant to conventional therapies. The typical treatment for PC is a combination of cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC). Recently, research in this area has seen significant advances, particularly in immunotherapy as an alternative therapy for PC, which is very encouraging. Catumaxomab is a trifunctional antibody intraperitoneal (IP) immunotherapy authorized in Europe that can be used to diminish malignant ascites by targeting EpCAM. Intraperitoneal (IP) immunotherapy breaks immunological tolerance to treat peritoneal illness. Increasing T-cell responses and vaccination against tumor-associated antigens are two methods of treatment. CAR-T cells, vaccine-based therapeutics, dendritic cells (DCs) in combination with pro-inflammatory cytokines and NKs, adoptive cell transfer, and immune checkpoint inhibitors are promising treatments for PC. Carcinoembryonic antigen-expressing tumors are suppressed by IP administration of CAR-T cells. This reaction was strengthened by anti-PD-L1 or anti-Gr1. When paired with CD137 co-stimulatory signaling, CAR-T cells for folate receptor cancers made it easier for T-cell tumors to find their way to and stay alive in the body.

CDX-2 expression correlates with clinical outcomes in MSI-H metastatic colorectal cancer patients receiving immune checkpoint inhibitors

Immune checkpoint inhibitors (ICIs) showed efficacy in metastatic colorectal cancer (mCRC) with mismatch-repair deficiency or high microsatellite instability (dMMR-MSI-H). Unfortunately, a patient's subgroup did not benefit from immunotherapy. Caudal-related homeobox transcription factor 2 (CDX-2) would seem to influence immunotherapy's sensitivity, promoting the chemokine (C-X-C motif) ligand 14 (CXCL14) expression. Therefore, we investigated CDX-2 role as a prognostic-predictive marker in patients with mCRC MSI-H. We retrospectively collected data from 14 MSI-H mCRC patients treated with ICIs between 2019 and 2021. The primary endpoint was the 12-month progression-free-survival (PFS) rate. The secondary endpoints were overall survival (OS), PFS, objective response rate (ORR), and disease control rate (DCR). The PFS rate at 12 months was 81% in CDX-2 positive patients vs 0% in CDX-2 negative patients (p = 0.0011). The median PFS was not reached (NR) in the CDX-2 positive group versus 2.07 months (95%CI 2.07-10.8) in CDX-2 negative patients (p = 0.0011). Median OS was NR in CDX-2-positive patients versus 2.17 months (95% Confidence Interval [CI] 2.17-18.7) in CDX2-negative patients (p = 0.026). All CDX-2-positive patients achieved a disease response, one of them a complete response. Among CDX-2-negative patients, one achieved stable disease, while the other progressed rapidly (ORR: 100% vs 0%, p = 0.0005; DCR: 100% vs 50%, p = 0.02). Twelve patients received 1st-line pembrolizumab (11 CDX-2 positive and 1 CDX-2 negative) not reaching median PFS, while two patients (1 CDX-2 positive and 1 CDX-2 negative) received 3rd-line pembrolizumab reaching a median PFS of 10.8 months (95% CI, 10.8-12.1; p = 0.036). Although our study reports results on a small population, the prognostic role of CDX-2 in CRC seems confirmed and could drive a promising predictive role in defining the population more sensitive to immunotherapy treatment. Modulating the CDX-2/CXCL14 axis in CDX-2-negative patients could help overcome primary resistance to immunotherapy.

The molecular biology of peritoneal metastatic disease

Peritoneal metastases are a common form of tumor cell dissemination in gastrointestinal malignancies. Peritoneal metastatic disease (PMD) is associated with severe morbidity and resistance to currently employed therapies. Given the distinct route of dissemination compared with distant organ metastases, and the unique microenvironment of the peritoneal cavity, specific tumor cell characteristics are needed for the development of PMD. In this review, we provide an overview of the known histopathological, genomic, and transcriptomic features of PMD. We find that cancers representing the mesenchymal subtype are strongly associated with PMD in various malignancies. Furthermore, we discuss the peritoneal niche in which the metastatic cancer cells reside, including the critical role of the peritoneal immune system. Altogether, we show that PMD should be regarded as a distinct disease entity, that requires tailored treatment strategies.

Impact of Patient Characteristics on the Outcomes of Patients with Gastrointestinal Cancers Treated with Immune Checkpoint Inhibitors

Gastrointestinal (GI) cancers are a group of malignancies that globally account for a significant portion of cancer incidence and cancer-related death. Survival outcomes for esophageal, gastric, pancreatic, and hepatobiliary cancers remain poor, but new treatment paradigms are emerging with the advent of immune checkpoint inhibitor (ICI) therapy. This review characterizes patient-related prognostic factors that influence the response to ICI therapy. We performed an analysis of the landmark randomized clinical trials in esophageal, gastric, colorectal, hepatocellular, pancreatic, and biliary tract cancers in terms of patient demographic factors. A literature review of smaller retrospective studies investigating patient-related factors was completed. The immunological bases for these associations were further explored. The key predictive factors identified include age, sex, performance status, geography, body mass index, sarcopenia, gut microbiome, various biochemical factors, and disease distribution.

Association of immune-related adverse events with the outcomes of immune checkpoint inhibitors in patients with dMMR/MSI-H metastatic colorectal cancer

BACKGROUND

Immune checkpoint inhibitors (ICIs) show a tremendous activity in microsatellite instability-high (MSI-H) metastatic colorectal cancer (mCRC), but a consistent fraction of patients does not respond. Prognostic/predictive markers are needed. Despite previous investigations in other tumor types, immune-related adverse events (irAEs) have not been well evaluated in patients with MSI-H cancers treated with ICIs.

METHODS

We conducted an international cohort study at tertiary cancer centers collecting clinic-pathological features from 331 patients with MSI-H mCRC treated with ICIs. Of note, the irAEs were summarized using a 'burden score' constructed in a way that the same score value could be obtained by cumulating many low-grade irAEs or few high-grade irAEs; as a result, the lower the burden the better. Clearly, the irAE burden is not a baseline information, thus it was modeled as a time-dependent variable in univariable and multivariable Cox models.

RESULTS

Among 331 patients, irAEs were reported in 144 (43.5%) patients. After a median follow-up time of 29.7 months, patients with higher burden of skin, endocrine and musculoskeletal irAEs (the latter two's effect was confirmed at multivariable analysis) had longer overall survival (OS), as opposed to gastrointestinal, pneumonitis, neurological, liver, renal and other irAEs, which showed an harmful effect. Similar results were observed for progression-free survival (PFS). Based on the results retrieved from organ-specific irAEs, 'aggregated' burden scores were developed to distinguish 'protective' (endocrine and musculoskeletal) and 'harmful' (gastrointestinal, pneumonitis, neurological, hepatic) irAEs showing prognostic effects on OS and PFS.

CONCLUSIONS

Our results demonstrate that not all irAEs could exert a protective effect on oncologic outcome. An easy-to-use model for ICIs toxicity (burden score of protective and harmful irAEs) may be used as surrogate marker of response.

Modeling resistance of colorectal peritoneal metastases to immune checkpoint blockade in humanized mice

BACKGROUND

The immunogenic nature of metastatic colorectal cancer (CRC) with high microsatellite instability (MSI-H) underlies their responsiveness to immune checkpoint blockade (ICB). However, resistance to ICB is commonly observed, and is associated with the presence of peritoneal-metastases and ascites formation. The mechanisms underlying this site-specific benefit of ICB are unknown.

METHODS

We created a novel model for spontaneous multiorgan metastasis in MSI-H CRC tumors by transplanting patient-derived organoids (PDO) into the cecum of humanized mice. Anti-programmed cell death protein-1 (PD-1) and anti-cytotoxic T-lymphocytes-associated protein 4 (CTLA-4) ICB treatment effects were analyzed in relation to the immune context of primary tumors, liver metastases, and peritoneal metastases. Immune profiling was performed by immunohistochemistry, flow cytometry and single-cell RNA sequencing. The role of B cells was assessed by antibody-mediated depletion. Immunosuppressive cytokine levels (interleukin (IL)-10, transforming growth factor (TGF)b1, TGFb2, TGFb3) were determined in ascites and serum samples by ELISA.

RESULTS

PDO-initiated primary tumors spontaneously metastasized to the liver and the peritoneum. Peritoneal-metastasis formation was accompanied by the accumulation of ascites. ICB completely cleared liver metastases and reduced primary tumor mass but had no effect on peritoneal metastases. This mimics clinical observations. After therapy discontinuation, primary tumor masses progressively decreased, but peritoneal metastases displayed unabated growth. Therapy efficacy correlated with the formation of tertiary lymphoid structures (TLS)-containing B cells and juxtaposed T cells-and with expression of an interferon-γ signature together with the B cell chemoattractant CXCL13. B cell depletion prevented liver-metastasis clearance by anti-CTLA-4 treatment. Peritoneal metastases were devoid of B cells and TLS, while the T cells in these lesions displayed a dysfunctional phenotype. Ascites samples from patients with cancer with peritoneal metastases and from the mouse model contained significantly higher levels of IL-10, TGFb1, TGFb2 and TGFb3 than serum samples.

CONCLUSIONS

By combining organoid and humanized mouse technologies, we present a novel model for spontaneous multiorgan metastasis by MSI-H CRC, in which the clinically observed organ site-dependent benefit of ICB is recapitulated. Moreover, we provide empirical evidence for a critical role for B cells in the generation of site-dependent antitumor immunity following anti-CTLA-4 treatment. High levels of immunosuppressive cytokines in ascites may underlie the observed resistance of peritoneal metastases to ICB.

The distinct clinical trajectory, metastatic sites, and immunobiology of microsatellite-instability-high cancers

Microsatellite-instability-high (MSI-H) cancers form a spectrum of solid organ tumors collectively known as Lynch Syndrome cancers, occurring not only in a subset of colorectal, endometrial, small bowel, gastric, pancreatic, and biliary tract cancers but also in prostate, breast, bladder, and thyroid cancers. Patients with Lynch Syndrome harbor germline mutations in mismatch repair genes, with a high degree of genomic instability, leading to somatic hypermutations and, therefore, oncogenesis and cancer progression. MSI-H cancers have unique clinicopathological characteristics compared to their microsatellite-stable (MSS) counterparts, marked by a higher neoantigen load, immune cell infiltration, and a marked clinical response to immune checkpoint blockade. Patients with known Lynch Syndrome may be detected early through surveillance, but some patients present with disseminated metastatic disease. The treatment landscape of MSI-H cancers, especially colorectal cancers, has undergone a paradigm shift and remains to be defined, with immune checkpoint blockade coming to the forefront of treatment strategies in the stage IV setting. We summarize in this review the clinical features of MSI-H cancers with a specific interest in the pattern of spread or recurrence, disease trajectory, and treatment strategies. We also summarize the tumor-immune landscape and genomic profile of MSI-H cancers and potential novel therapeutic strategies.

A PD-L1-targeting chimeric switch receptor enhances efficacy of CAR-T cell for pleural and peritoneal metastasis

Pleural and peritoneal metastasis accompanied by malignant pleural effusion (MPE) or malignant ascites (MA) is frequent in patients with advanced solid tumors that originate from the lung, breast, gastrointestinal tract and ovary. Regional delivery of CAR-T cells represents a new strategy to control tumor dissemination in serous cavities. However, malignant effusions constitute an immune-suppressive environment that potentially induces CAR-T cell dysfunction. Here, we demonstrated that the anti-tumor cytotoxicity of conventional 2nd-generation CAR-T cells was significantly inhibited by both the cellular and non-cellular components of MPE/MA, which was primarily attributed to impaired CAR-T cell proliferation and cytokine production in MPE/MA environment. Interestingly, we found that PD-L1 was widely expressed on freshly-isolated MPE/MA cells. Based on this feature, a novel PD-L1-targeting chimeric switch receptor (PD-L1.BB CSR) was designed, which can bind to PD-L1, switching the inhibitory signal into an additional 4-1BB signal. When co-expressed with a 2nd-generation CAR, PD-L1.BB CSR-modified CAR-T cells displayed superior fitness and enhanced functions in both culture medium and MPE/MA environment, causing rapid and durable eradication of pleural and peritoneal metastatic tumors in xenograft models. Further investigations revealed elevated expressions of T-cell activation, proliferation, and cytotoxicity-related genes, and we confirmed that PD-L1 scFv and 4-1BB intracellular domain, the two important components of PD-L1.BB CSR, were both necessary for the functional improvements of CAR-T cells. Overall, our study shed light on the clinical application of PD-L1.BB CSR-modified dual-targeting CAR-T cells. Based on this study, a phase I clinical trial was initiated in patients with pleural or peritoneal metastasis (NCT04684459).

Clinical prospects of WRN inhibition as a treatment for MSI tumours

The discovery of synthetic lethal interactions with genetic deficiencies in cancers has highlighted several candidate targets for drug development, with variable clinical success. Recent work has unveiled a promising synthetic lethal interaction between inactivation/inhibition of the WRN DNA helicase and tumours with microsatellite instability, a phenotype that arises from DNA mismatch repair deficiency. While these and further studies have highlighted the therapeutic potential of WRN inhibitors, compounds with properties suitable for clinical exploitation remain to be described. Furthermore, the complexities of MSI development and its relationship to cancer evolution pose challenges for clinical prospects. Here, we discuss possible paths of MSI tumour development, the viability of WRN inhibition as a strategy in different scenarios, and the necessary conditions to create a roadmap towards successful implementation of WRN inhibitors in the clinic.

The Optimal Therapy after Progression on Immune Checkpoint Inhibitors in MSI Metastatic Gastrointestinal Cancer Patients: A Multicenter Retrospective Cohort Study

Simple Summary

Programmed death 1 (PD1)/programmed death ligand-1 (PD-L1) inhibitor is the standard therapy for advanced microsatellite instability (MSI)/mismatch repair-deficient (dMMR) gastrointestinal cancers. However, the suitable therapy after the progression of anti-PD1/PD-L1 for MSI/dMMR gastrointestinal cancer patients was unknown, until now. Here, we conducted a retrospective study to evaluate the efficacy of anti-PD1/PD-L1 plus other drug therapy versus chemotherapy with or without targeted therapy for patients who had progressed on prior anti-PD1/PD-L1 monotherapy. Our study found that anti-PD1/PD-L1 plus other drug therapy had significantly improved the disease control rate, progression-free survival, and overall survival, along with a numerically higher objective response rate versus chemotherapy with or without targeted therapy. The promising findings of our retrospective study need to be further confirmed in prospective trials.

Abstract

Background: In microsatellite instability (MSI)/mismatch repair-deficient (dMMR) gastrointestinal cancers, the optimum therapy after the progression of immune checkpoint inhibitors (ICIs) is yet unknown. Here, we compared the efficacy of programmed death 1 (PD1)/programmed death ligand-1 (PD-L1) inhibitors plus other therapy and chemotherapy with or without targeted therapy in MSI/dMMR gastrointestinal cancer patients after progression on anti-PD1/PD-L1 monotherapy. Methods: We retrospectively recruited MSI/dMMR gastrointestinal cancer patients who had progressed on anti-PD1/PD-L1 monotherapy. Objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), overall survival (OS), and PFS ratio (PFSr) were compared between patients who received anti-PD1/PD-L1 plus other therapy (ICI-plus group) and patients who received chemotherapy with or without targeted therapy (chemo-targeted group). Results: In total, 26 and 25 patients were recruited in the ICI-plus group and chemo-targeted group, respectively. Significantly better DCR (80.8% vs. 44.0%, p = 0.007), PFS (median PFS 6.9 months vs. 3.0 months, p = 0.001), OS (median OS NR vs. 14.1 months, p = 0.043), and PFSr (2.4 vs. 0.9, p = 0.021), along with a numerically higher ORR (23.1% vs. 12.0%, p = 0.503) were observed in the ICI-plus group compared with the chemo-targeted group. Multivariate analyses identified the therapy regimen as an important prognostic factor in gastrointestinal cancers. Conclusions: Compared to conventional chemotherapy with or without targeted therapy, continuing anti-PD1/PD-L1 in combination with other treatments showed better clinical outcomes in MSI/dMMR gastrointestinal cancer patients who progressed on PD1/PD-L1 blockade, which should be validated prospectively in clinical trials.

Immune checkpoint inhibitors for patients with isolated peritoneal carcinomatosis from dMMR/MSI-H colorectal cancer, a BIG-RENAPE collaboration

BACKGROUND

Immunotherapy with immune checkpoint inhibitors has significantly improved the survival of patients with MSI/dMMR mCRC. These tumors are associated with a specific metastatic spread, i.e. frequent peritoneal carcinomatosis (PC) that may be treated surgically when there is no other metastatic location. We aimed at evaluating the prognosis of patients treated with immune checkpoint inhibitors for MSI/dMMR mCRC with isolated PC.

MATERIAL AND METHODS

All consecutive patients with isolated PC from MSI/dMMR mCRC, initially considered as unresectable by multidisciplinary team meeting, treated with immune checkpoint inhibitors were included in this French multicenter cohort study.

RESULTS

Among 45 patients included, we observed 11 complete responses and 10 partial responses for an overall response rate iRECIST of 46%. After a median follow-up of 24.4 months, the median progression-free survival (PFS) and overall survival (OS) were not reached. Seven of the eight patients who underwent cytoreductive surgery after treatment with anti-PD1 ± anti-CTLA-4 were in complete pathologic response.

CONCLUSION

These results demonstrate long-term benefit of immune checkpoint inhibitors for patients with isolated PC from MSI/dMMR mCRC. Such treatment appears as the best therapeutic option for patients with isolated PC from MSI/dMMR mCRC. With a majority of pathological complete responses for patients who underwent surgery for residual lesions, the value of such therapeutic strategy remains unknown.

Immune-Checkpoint Inhibitors (ICIs) in Metastatic Colorectal Cancer (mCRC) Patients beyond Microsatellite Instability

Immune-checkpoint inhibitors (ICIs) showed impressive results in terms of activity and efficacy in metastatic colorectal cancer (mCRC) patients bearing tumors with deficient mismatch repair (dMMR) or high microsatellite instability (MSI-H). Despite that microsatellite status is the major predictive biomarker for the efficacy of ICIs, a proportion of dMMR/MSI-H mCRC tumors do not achieve benefit from immunotherapy due to the primary resistance. Deeper knowledge of biological mechanisms regulating dMMR/MSI-H CRC tumors and immune response may be useful to find new predictive biomarkers of ICIs benefit and tailor the use of immunotherapy even in dMMR/MSI-H mCRC patients. Moreover, several issues are still open, such as the secondary resection of metastases and the optimal duration of ICIs therapy in dMMR/MSI-H mCRC patients. Looking beyond microsatellite status, in a future perspective, several tools (i.e., Tumor Mutational Burden and PD-L1 expression) have been investigated to clarify their possible role as predictive biomarkers. Furthermore, a small subgroup of pMMR/MSS CRC tumors with a POLE mutation of the proofreading domain is characterized by hypermutated phenotype and might derive benefit from immune checkpoint inhibition. In the present work, we aim to review the most recent literature regarding treatment with ICIs in mCRC, focusing on dMMR/MSI-H and special subgroups of CRC patients. Hence, we summarize possible future targets and the most promising predictive biomarkers.

Multi-omics analysis of the oncogenic value of copper Metabolism-Related protein COMMD2 in human cancers

BACKGROUND

The copper metabolism MURR1 domain (COMMD) protein family is involved in tumorigenicity of malignant tumors. However, as the member of COMMD, the role of COMMD2 in human tumors remains unknown.

METHODS

We used The Cancer Genome Atlas (TCGA), Genotype Tissue Expression (GTEx), Human Protein Atlas (HPA) database, Cancer Cell Line Encyclopedia (CCLE) platform, univariate Cox regression analysis, Kaplan-Meier curve, cBioPortal, UALCAN database, Sangerbox online platform, GSCA database gene set enrichment analysis (GSEA), and GeneMANIA to analyze the expression of COMMD2, its prognostic values, genomic alteration patterns, and the correlation with tumor stemness, tumor mutational burden (TMB), microsatellite instability (MSI), and immune infiltrates, drug sensitivity, and gene function enrichment in pan-cancer. qRT-PCR, CCK-8, EdU, wound healing, and transwell migration assays were performed to confirm the function of COMMD2.

RESULTS

COMMD2 was strongly expressed in most cancer types. Elevated COMMD2 expression affects the prognosis, clinicopathological stage, and molecular or immune subtypes of various tumors. Moreover, promoter hypomethylation and mutations in the COMMD2 gene may be associated with its high expression and poor survival. Additionally, we discovered that COMMD2 expression was linked to tumor stemness, TMB, MSI, immune cell infiltration, immune-checkpoint inhibitors, and drug sensitivity in pan-cancer. Furthermore, the COMMD2 gene co-expression network is constructed with GSEA analysis, displaying significant interaction of COMMD2 with E2F targets, G2-M checkpoint, and mitotic spindle in bladder cancer (BLCA). Finally, RNA interference data showed suppression of COMMD2 prevented proliferation and migration of BLCA and uterine corpus endometrial carcinoma (UCEC) cells.

CONCLUSION

Our findings shed light on the COMMD2 functions in human cancers and demonstrate that it is a promising prognostic biomarker and therapeutic target in pan-cancer.

Biomarkers in Metastatic Colorectal Cancer: Status Quo and Future Perspective

Colorectal cancer (CRC) is the third most frequent cancer worldwide, and its incidence is steadily increasing. During the last two decades, a tremendous improvement in outcome has been achieved, mainly due to the introduction of novel drugs, targeted treatment, immune checkpoint inhibitors (CPIs) and biomarker-driven patient selection. Moreover, progress in molecular diagnostics but also improvement in surgical techniques and local ablative treatments significantly contributed to this success. However, novel therapeutic approaches are needed to further improve outcome in patients diagnosed with metastatic CRC. Besides the established biomarkers for mCRC, such as microsatellite instability (MSI) or mismatch repair deficiency (dMMR), RAS/BRAF, sidedness and HER2 amplification, new biomarkers have to be identified to better select patients who derive the most benefit from a specific treatment. In this review, we provide an overview about therapeutic relevant and established biomarkers but also shed light on potential promising markers that may help us to better tailor therapy to the individual mCRC patient in the near future.

Primary and secondary immune checkpoint inhibitors resistance in colorectal cancer: Key mechanisms and ways to overcome resistance

Immune checkpoint inhibitors (ICIs) have significantly advanced colorectal cancer treatment in recent years. Antibodies that target the proteins programmed cell death-1 (PD-1), programmed cell death-1 ligand 1 (PD-L1), and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) are among the ICIs that are currently being used in clinical practice. However, in colorectal cancer, ICI's effectiveness is limited to a fraction of patients with microsatellite instability-high (MSI-H), which only accounts for about 5% of advanced cases. The tumor microenvironment and intrinsic changes in tumor cells are just a couple of the many mechanisms that play a role in ICI primary or secondary resistance. In order to advance precision medicine and broaden the population benefiting from ICI, this paper highlights the main underlying mechanisms of ICIs resistance and suggested techniques to overcome it.

Therapeutic targets and biomarkers of tumor immunotherapy: response versus non-response

Cancers are highly complex diseases that are characterized by not only the overgrowth of malignant cells but also an altered immune response. The inhibition and reprogramming of the immune system play critical roles in tumor initiation and progression. Immunotherapy aims to reactivate antitumor immune cells and overcome the immune escape mechanisms of tumors. Represented by immune checkpoint blockade and adoptive cell transfer, tumor immunotherapy has seen tremendous success in the clinic, with the capability to induce long-term regression of some tumors that are refractory to all other treatments. Among them, immune checkpoint blocking therapy, represented by PD-1/PD-L1 inhibitors (nivolumab) and CTLA-4 inhibitors (ipilimumab), has shown encouraging therapeutic effects in the treatment of various malignant tumors, such as non-small cell lung cancer (NSCLC) and melanoma. In addition, with the advent of CAR-T, CAR-M and other novel immunotherapy methods, immunotherapy has entered a new era. At present, evidence indicates that the combination of multiple immunotherapy methods may be one way to improve the therapeutic effect. However, the overall clinical response rate of tumor immunotherapy still needs improvement, which warrants the development of novel therapeutic designs as well as the discovery of biomarkers that can guide the prescription of these agents. Learning from the past success and failure of both clinical and basic research is critical for the rational design of studies in the future. In this article, we describe the efforts to manipulate the immune system against cancer and discuss different targets and cell types that can be exploited to promote the antitumor immune response.

Deficient mismatch repair/microsatellite unstable colorectal cancer: Diagnosis, prognosis and treatment

Microsatellite unstable (MSI) colorectal cancers (CRCs) are due to DNA mismatch repair (MMR) deficiency and occurs in15% of non-metastatic diseases and 5% in the metastatic setting. Nearly 30% of MSI CRCs occur in a context of constitutional mutation of the MMR system (Lynch syndrome). Others are sporadic cancers linked to a hypermethylation of the MLH-1 promoter. The pathogenic alterations of MMR genes lead to the accumulation of frequent somatic mutational events and these tumours arbour a high antigen burden and are highly infiltrated with cytotoxic T-cell lymphocytes. Microsatellite instability/DNA mismatch repair deficiency (MSI/dMMR) status has prognostic and predictive implications in non-metastatic and metastatic CRCs. The prognostic value of MSI status in non-metastatic CRCs has been studied extensively, yet the data are more limited for its predictive value in terms of adjuvant chemotherapy efficacy. In both cases (metastatic and non-metastatic settings) treatment with immune check-point inhibitors (ICIs) have shown a remarkable effectiveness in the context of MSI/dMMR status. Indeed, recent data from prospective cohorts and randomised trials have shown a dramatical improvement of survival with immunotherapy (programmed death-ligand 1 [PD-(L)1]   cytotoxic T-lymphocyte-associated antigen 4 [CTLA-4] blockage) in metastatic or non-metastatic MSI/dMMR CRC. In this review we report and discuss how and for whom to test for the MSI/dMMR phenotype, as well as the prognostic value of this phenotype and the new treatment recommendations options for this unique CRC population. Despite their efficacy, primary and secondary resistance to immune checkpoint inhibitors (ICIs) are observed in more than 50% MSI-H/dMMR CRC patients and in the future how to identify these patients and to overcome resistance will be an important challenge.

Updated Efficacy Outcomes of Anti-PD-1 Antibodies plus Multikinase Inhibitors for Patients with Advanced Gastric Cancer with or without Liver Metastases in Clinical Trials

PURPOSE

We previously reported preliminary activity of regorafenib plus nivolumab (REGONIVO) or lenvatinib plus pembrolizumab (LENPEM) in advanced gastric cancer (AGC). Meanwhile, several studies demonstrated liver metastases are less responsive to immunotherapy.

PATIENTS AND METHODS

Combined efficacy outcomes with a longer follow-up in a phase Ib trial of REGONIVO and a phase II trial of LENPEM were examined in AGC with or without liver metastases (REGONIVO plus LENPEM cohort). We also investigated the efficacy of anti-PD-1 monotherapies (anti-PD-1 monotherapy cohort). A comparison of the immune microenvironment between gastric primary tumors and liver metastases was also conducted by multiplex IHC.

RESULTS

In the REGONIVO plus LENPEM cohort, with a median follow-up of 14.0 months, objective response rate (ORR), median progression-free survival (mPFS), and median overall survival (mOS) were 46%, 7.8 months, and 15.6 months in patients with liver metastases, while 69%, 6.9 months, and 15.5 months in those without. In the anti-PD-1 monotherapy cohort, with a median follow-up of 27.6 months, ORR, mPFS, and mOS were 9%, 1.4 months, and 6.4 months in patients with liver metastases, while 22%, 2.3 months, and 9.0 months in those without. Multiplex IHC revealed liver metastases were associated with an abundance of immune-suppressive cells, such as tumor-associated macrophages and regulatory T cells, with fewer CD8+ T cells compared with gastric primary tumors.

CONCLUSIONS

Anti-PD-1 antibodies plus regorafenib or lenvatinib for AGC showed promising antitumor activity with a longer follow-up, irrespective of liver metastases status, despite a more immune-suppressive tumor microenvironment in liver metastases.

Prognostic and predictive molecular biomarkers in advanced colorectal cancer

The revolution of precision medicine has produced unprecedented seismic shifts in the treatment paradigm of advanced cancers. Among the major killers, colorectal cancer (CRC) is far behind the others. In fact, the great successes obtained in breast, NSCLC, melanoma, and genitourinary tract tumors have been observed only in fewer than 5 % metastatic colorectal cancer (mCRC): those with the mismatch repair deficiency (dMMR), a well-known predictive factor for to the outstanding efficacy of checkpoint inhibitors (CPI). The treatment of the remaining vast majority mCRC patients is still based upon only two molecular determinants: the RAS and BRAF mutational status. New promising biomarkers include HER2, tumor mutational burden (TMB) for its possible implications on CPI efficacy, and the extremely rare NTRK fusions. The Consensus Molecular Subtypes classification (CMS) is a good example of the efforts to combine different molecular features of this disease, although its relevance in clinical practice is still under investigation. In this Review, we focus on all these prognostic and predictive biomarkers, analyzing data from the most important clinical trials of the last years. We also try to rank them according to their prognostic and predictive power.

Prognostic impact of performance status on the outcomes of immune checkpoint inhibition strategies in patients with dMMR/MSI-H metastatic colorectal cancer

BACKGROUND

Immune checkpoint inhibitors yielded unprecedented outcomes in patients with mismatch repair deficient/ microsatellite instability-high (dMMR/MSI-H) metastatic colorectal cancer (mCRC), but clinical decision-making in this rapidly evolving treatment landscape is challenging. Since performance status (PS) represents a well-established prognostic factor in clinical practice, we investigated whether worse PS, overall or related to either patients' frailty or high tumour burden, could affect the outcomes in this whole patients' population and according to immune checkpoint inhibitor treatment type.

METHODS

We conducted a global study at Tertiary Cancer Centres and collected data of patients with dMMR/MSI-H mCRC treated with anti- programmed-death (ligand)-1 (PD(L)-1) monotherapy or anti-PD-1/anti- cytotoxic T-lymphocyte antigen 4 combination.

RESULTS

The cohort included 502 patients. At a median follow-up of 31.2 months, worse PFS and OS were reported in patients with patient-related PS ≥ 1 (adjusted-HRs: 1.73, 95%CI: 1.06-2.83, p = 0.004 and 2.06, 95%CI: 1.13-3.74, p = 0.001, respectively) and cancer-related PS ≥ 1 (adjusted-HRs: 1.61, 95%CI: 1.19-2.17, p = 0.004 and 1.87, 95%CI: 1.32-2.66, p = 0.001, respectively). Anti-PD-1/anti- cytotoxic T-lymphocyte antigen 4 combination did not provide significantly better survival compared to anti-PD(L)-1 monotherapy in PS 0 subgroup (PFS HR = 0.62, 95%CI: 0.37-1.02, p = 0.059; OS HR = 0.59, 95%CI: 0.32-1.11, p = 0.100) and in patient-related PS ≥ 1 (PFS HR 0.93, 95%CI: 0.31-2.83, p = 0.899; OS HR 1.22, 95%CI: 0.34-4.37, p = 0.760), but the difference was significant and clinically meaningful in the subgroup with cancer-related PS ≥ 1 (PFS HR = 0.32, 95%CI: 0.19-0.53, p < 0.001; OS HR = 0.26, 95%CI: 0.14-0.48, p < 0.001).

CONCLUSIONS

In patients with dMMR/MSI-H mCRC, an extensive evaluation of clinical variables including PS may be implemented in the therapy decision-making.

Resistance to systemic immune checkpoint inhibition in the peritoneal niche

Immune checkpoint inhibition (ICI) is an established therapeutic option for patients with deficient mismatch repair or high levels of microsatellite instability tumors. Yet, response to ICI among this group is varied, with nearly one-third of patients exhibiting primary resistance. Initial efforts in studying mechanisms of resistance to ICI have focused on intrinsic tumor factors. Host factors such as metastatic niches have unique biological properties that may mediate resistance to ICI but have been less studied date. Patients with metastatic d-MMR/MSI-H gastrointestinal cancers and peritoneal metastases (PM) who had concurrent ascites have been recently shown to have worse outcomes with ICI therapy compared with patients with PM without ascites and patients with non-PM metastases. The juxtaposition of tumors with an intrinsic sensitivity to ICI failing to respond by virtue of the presence of ascites within the peritoneum, brings to the forefront the critical role of the metastatic niche. In this commentary, we discuss mechanisms for ICI resistance that may arise from the immunoprivileged state of the peritoneal cavity, paracrine factors within malignant ascites or tumor-peritoneum interactions. An improved understanding of the peritoneal microenvironment and the use of peritoneal-directed therapies may ameliorate the modest benefit of ICIs in this unique clinical entity.

Microsatellite Instability and Metastatic Colorectal Cancer - A Clinical Perspective

Approximately 4-5% of patients with metastatic colorectal cancer (mCRC) have mismatch repair deficient (dMMR)/microsatellite instability-high (MSI-H) tumours. These tumours present challenges in the clinical practice due to variant response to fluoropyrimidine-based chemotherapy and, perhaps, also non-immunologic targeted therapies. Recently, a breakthrough in the treatment of dMMR/MSI-H mCRC has been achieved with several clinical trials showing dramatic long-term benefit of immunotherapy using checkpoint inhibitors. Nevertheless, several questions remain regarding the optimisation of immunotherapy regimens and the use of biomarkers to identify populations set to derive the greatest benefit from immunotherapy. Combination regimens and/or the use of immunotherapy as a maintenance after induction non-immunologic systemic therapy may be the way forward to improve outcomes.