The Immune Biology of Microsatellite-Unstable Cancer

The usefulness of comprehensive genome profiling test in screening of Lynch syndrome independent of the conventional clinical screening or microsatellite instability tests

Lynch syndrome (LS) is a hereditary cancer predisposition syndrome caused by germline pathogenic variants of DNA mismatch repair (MMR) genes. To diagnose LS, the microsatellite instability (MSI) test or immunohistochemistry of MMR enzymes is used as a conventional clinical screening method for all patients with colorectal and endometrial cancers. Recently, patients with advanced-stage cancers have undergone comprehensive genomic profiling (CGP), which is useful not only for the detection of molecularly targeted personalized therapies, but also for the screening of hereditary cancer syndromes by determining presumed germline pathogenic variants (PGPVs). Between January 2020 and April 2024, 1583 patients underwent CGP at our institute. PGPVs in MMR genes were detected in 19 patients. Although one patient died prior to the disclosure of the results and eight patients declined confirmatory genetic testing, the remaining ten patients underwent confirmatory genetic tests, of whom six were found to have a hereditary origin. Two additional patients were diagnosed with LS using tumor-normal paired CGP. Eventually, a total of eight patients were diagnosed with LS. Herein, we describe two patients with microsatellite-stable cancer who could not be diagnosed using conventional clinical screening or MSI testing. Furthermore, we showed that pathogenic variants of MMR genes do not always correlate with high MSI prediction scores in several cancer types in The Cancer Genome Atlas (TCGA) dataset analysis. These findings highlight the usefulness of CGP as a screening tool to identify individuals with possible LS, especially when conventional criteria and MSI/MMR testing fail.

Discovery and validation of frameshift-derived neopeptides in Lynch syndrome: paving the way for novel cancer prevention strategies

BACKGROUND

Lynch syndrome (LS), caused by germline pathogenic variants in the mismatch repair genes, leads to high rates of frameshift-derived neopeptide (FSDN) expression due to microsatellite instability (MSI). While colorectal cancer (CRC) prevention is effective, most LS-related tumors lack such strategies. Cancer vaccines targeting FSDNs offer a promising approach for immune interception in LS. This study aimed to identify and validate LS-related FSDNs to develop vaccines for cancer prevention.

METHODS

We identified LS-related coding MS mutations and predicted FSDN with high coverage on common Human Leukocyte Antigen (HLA)-I and II alleles. We validated FSDN-associated mutations in colorectal adenomas (CrAD), endometrial cancers (EC), and CRC samples from patients with LS, non-LS tumors, and cell lines. Immunogenicity was assessed through interferon (IFN)-γ enzyme-linked immunospot and flow cytometry analysis of tissue-infiltrating lymphocytes (TILs) from LS carriers.

RESULTS

We prioritized 53 HLA-I and 45 HLA-II FSDNs in MSI tumors using in silico predictions. Validation revealed 86.7% of FSDN-associated mutations present in LS-CRC samples, with a median of 7.67 (6.5-9) mutations in CrADs and 6.02 (2-10) in CRCs. Sequencing of CrAD and EC samples showed 95% and 77.5% of predicted FSDN-associated mutations, respectively. MSI cancer cell lines transcribed 69.8% of FSDNs. Immunogenicity assays showed that 71% of potential FSDNs elicited IFN-γ responses, with a median of 7.37 (1-10.75) HLA-I and 6 (2-5.75) HLA-II FSDNs per patient. After prioritizing 24 FSDN, in a cohort of 19 LS-derived samples (4 CrAD and 15 normal mucosa), 52% (10/19) demonstrated T-cell reactivity to an HLA-I neoantigen pool. CD8+CD137+ activation markers increased significantly (p=0.037) over time and peptide-specific cells were detected by pentamer staining.

CONCLUSIONS

Our predicted FSDN set has optimal coverage among LS carriers and can induce IFN-γ inflammatory responses in LS-derived TILs, offering an opportunity for vaccine development.

Genetic immune escape in cancer: timing and implications for treatment

Genetic immune escape (GIE) alterations pose a significant challenge in cancer by enabling tumors to evade immune detection. These alterations, which can vary significantly across cancer types, may often arise early in clonal evolution and contribute to malignant transformation. As tumors evolve, GIE alterations are positively selected, allowing immune-resistant clones to proliferate. In addition to genetic changes, the tumor microenvironment (TME) and non-genetic factors such as inflammation, smoking, and environmental exposures play crucial roles in promoting immune evasion. Understanding the timing and mechanisms of GIE, alongside microenvironmental influences, is crucial for improving early detection and developing more effective therapeutic interventions. This review highlights the implications of GIE in cancer development and immunotherapy resistance, and emphasizes the need for integrative approaches.

Integrative analysis of bulk and single-cell sequencing reveals TNFSF9 as a potential regulator in microsatellite instability stomach adenocarcinoma

BACKGROUND

Stomach adenocarcinoma (STAD) with microsatellite instability (MSI) is associated with a better prognosis compared to Non-MSI. This study aims to elucidate the differences in the tumor microenvironment (TME) of MSI and explore its underlying mechanisms in STAD.

METHODS

TME differences between MSI and Non-MSI were analyzed using single-cell RNA sequencing (MSI = 7, Non-MSI = 19) and bulk RNA sequencing (MSI = 39, Non-MSI = 198). Differentially expressed genes (DEGs) were used to identify enriched pathways and hub genes. TNFSF9 expression was validated by immunohistochemistry (IHC) on 23 STAD sections (MSI = 13, Non-MSI = 10) and confirmed in tumor epithelial cells using SNU-1 (MSI) and AGS (Non-MSI) cell lines through quantitative polymerase chain reaction (qPCR) and Western blot (WB).

RESULTS

The results showed MSI was significantly associated with a better prognosis (P < 0.05). Within the TME, MSI was associated with a higher abundance of antigen-presenting cells, including M1 macrophages (40.1% vs. 27.9%) and activated dendritic cells (22.1% vs. 10.5%), as well as pro-inflammatory Th1-like CD4⁺ T cells (15% vs. 11%). However, MSI also showed an increase in exhausted T cells, indicating a complex immune landscape. Signaling pathway and cell communication analyses revealed an enrichment of cytokine-related pathways in MSI. Hub gene analysis revealed that TNFSF9 was predominantly expressed in stromal cells and partially in tumor epithelial cells in MSI, with its upregulation further confirmed through IHC, qPCR, and WB. Correlation analysis demonstrated a positive relationship between TNFSF9 expression and the abundance of M1 macrophages.

CONCLUSIONS

These findings provide new insights into the TME of MSI in STAD, emphasizing the significant role of TNFSF9 in shaping MSI-specific TME, enhancing immunotherapy efficacy, and improving patient survival.

Enhancing Colorectal Cancer Treatment Through VEGF/VEGFR Inhibitors and Immunotherapy

OPINION STATEMENT

Colorectal cancer, ranking as the third most prevalent malignancy globally, substantially benefits from both immunotherapy and VEGF/VEGFR inhibitors. Nevertheless, the use of monotherapy proves inadequate in effectively tackling the heterogeneity of tumors and the intricacies of their microenvironment, frequently leading to drug resistance and immune evasion. This situation underscores the pressing need for innovative strategies aimed at augmenting the effectiveness and durability of treatments. Clinical research demonstrates that the combination of VEGF/VEGFR inhibitors (primarily including VEGF/VEGFR-targeted drugs and multi-kinase inhibitors) with immune checkpoint inhibitors creates a synergistic effect in the treatment of colorectal cancer. Our analysis explores how VEGF/VEGFR inhibitors recalibrate the tumor microenvironment, modulate immune cell functions, and influence the expression of immune checkpoints and cytokines. Furthermore, we critically evaluate the preclinical and clinical feasibility of these combined therapeutic approaches. Despite the potential for toxicity, the significant benefits and prospective applications of these strategies warrant thorough exploration. Exploring the synergistic mechanisms of these combined treatments has the potential to inaugurate a new paradigm in oncology, enabling more personalized and efficacious treatment modalities. Additionally, the synergy between VEGF/VEGFR inhibitors and nascent immunotherapies emerges as a promising field of inquiry.

Generation of frameshift-mutated TGFβR2-specific T cells in healthy subjects following administration with cancer vaccine candidate FMPV-1/GM-CSF in a phase 1 study

FMPV-1 is a component of FMPV-3, an investigational cancer-specific vaccine and being developed to activate anti-cancer T cell responses targeting frameshift mutations of MSI-H cancers. FMPV-1 is designed to activate T cell responses against transforming growth factor β receptor 2 (TGFβR2) frameshift mutation. Microsatellite instability high (MSI-H) gastrointestinal cancers frequently harbour TGFβR2 frameshift mutations. This first-in-human, phase 1, single centre, open-label study included 16 healthy male subjects who received FMPV-1 (0.15 mg/injection) plus granulocyte-macrophage colony-stimulating factor (GM-CSF) (0.03 mg/injection) as two separate, co-located, injections on Days 1, 8, 15, 29 and 43. All subjects were followed to Day 365. A FMPV-1-specific delayed type hypersensitivity (DTH) skin reactivity test was performed with FMPV-1 (without GM-CSF) on Days 1, 29 and 43 with assessment after 2 days. All subjects were DTH negative at baseline, 8/16 were positive on Day 31 and 15/16 were positive on Day 45. Furthermore, the FMPV-1/GM-CSF induced frameshift mutant TGFβR2-specific T cells after the short vaccination period, and specific T cells were still detectable after 6 and 12 months indicating induction of frameshift mutant TGFβR2-specific T memory cells. Adverse events were limited to mild injection site reactions with no evidence of related systemic signs or symptoms. No other clinically important changes to vital signs, electrocardiograms, haematological, coagulation or laboratory measures related to treatment were observed. FMPV-1/GM-CSF was well tolerated and generated vaccine-specific T cell immune responses in healthy subjects. These findings support clinical studies in patients with, or at risk of, cancers carrying TGFβR2 frameshift mutations.Clinical trial identification: ClinicalTrials.gov: NCT05238558. EudraCT: 2020-004363-80.

Cytosolic DNA composition is determined by genomic instability mechanism and regulates dendritic cell-mediated anti-tumor immunity

Patients with colorectal cancers (CRCs) that have microsatellite instability (MSI) (MSI CRCs) face a better prognosis than those with the more common chromosomal instability (CIN) subtype (CIN CRCs) due to improved T cell-mediated anti-tumor immune responses. Previous investigations identified the cytosolic DNA (cyDNA) sensor STING as necessary for chemokine-mediated T cell recruitment in MSI CRCs. Here, we find that cyDNA from MSI CRC cells is inherently more capable of inducing STING activation and improves cytotoxic T cell activation by dendritic cells (DCs). Sequencing indicates that MSI cyDNA is enriched in microsatellites, which, upon DC uptake, induce anti-tumor immunity in a manner consistent with clinical MSI CRCs. DNA-damaging therapies also modulate cyDNA stimulation capacity, with radiation inducing larger cyDNA sizes and increased mitochondrial DNA content. Identifying highly stimulatory endogenous cyDNAs such as those in MSI CRCs will allow for optimized development of DNA-based STING agonist therapies to improve the responses of CIN CRCs with CIN to immunotherapies.

Efficacy and safety of PD-1/PD-L1 inhibitors in advanced or recurrent endometrial cancer: a meta-analysis with trial sequential analysis of randomized controlled trials

Background

The combination of programmed cell death 1 (PD-1)/programmed death ligand 1 (PD-L1) inhibitors with chemotherapy (CT) is currently under evaluation as a first-line treatment for advanced or recurrent endometrial cancer (EC). This study sought to assess the efficacy and safety of this therapeutic combination in patients with advanced or recurrent EC.

Methods

We performed an exhaustive review of randomized controlled trials (RCTs) up to September 25, 2024, examining the efficacy and safety of combining PD-1/PD-L1 inhibitors with CT versus CT alone (or plus placebo) in advanced or recurrent EC. Efficacy was measured by progression-free survival (PFS) and overall survival (OS), while safety was assessed by the incidence of any grade or grade ≥ 3 adverse events (AEs). We calculated hazard ratios (HRs) for PFS and OS, as well as risk ratios (RRs) for AEs, each accompanied by 95% confidence intervals (CIs). To evaluate heterogeneity, we employed Cochran's Q test, I2 statistics, and 95% prediction intervals (PIs). Trial sequential analysis (TSA) was conducted using R Version 4.3.1, STATA Version 12.0, and TSA Version 0.9.5.10 Beta software.

Results

Our analysis incorporated 6 studies, encompassing a total of 2,954 patients. The combination of PD-1/PD-L1 inhibitors with CT significantly improved PFS (HR = 0.617, 95% CI: 0.506-0.752; 95% PI: 0.334-1.140) and OS (HR = 0.774, 95% CI: 0.664-0.902; 95% PI: 0.553-1.083) compared to CT alone (or plus placebo) in the overall population. Subgroup analysis based on mismatch repair (MMR) status revealed pronounced benefits in PFS and OS for patients with deficient MMR (dMMR) (PFS: HR = 0.344, 95% CI: 0.269-0.438; 95% PI: 0.231-0.510; OS: HR = 0.371, 95% CI: 0.245-0.562; 95% PI: 0.025-5.461) compared to those with proficient MMR (pMMR) (PFS: HR = 0.772, 95% CI: 0.627-0.950; 95% PI: 0.394-1.512; OS: HR = 0.996, 95% CI: 0.692-1.435; 95% PI: 0.021-47.662). Although there was no observed difference in the incidence of any grades AEs (RR = 0.994, 95% CI: 0.982-1.006; 95% PI: 0.978-1.009), the risk of grade ≥ 3 AEs was elevated in the group receiving PD-1/PD-L1 inhibitors in combination with CT (RR = 1.132, 95% CI: 1.023-1.252; 95% PI: 0.836-1.532).

Conclusion

The combination of PD-1/PD-L1 inhibitors with CT significantly improved PFS and OS in advanced or recurrent EC patients, with particularly pronounced benefits observed in those with dMMR. Clinicians can tailor treatment strategies according to individual patient characteristics to optimize therapeutic outcomes, while remaining alert to the possibility of AEs in clinical practice.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42024595455.

Immune checkpoint inhibitors for patients with mismatch repair deficient or microsatellite instability-high advanced cancers: a meta-analysis of phase I-III clinical trials

BACKGROUND

Mismatch repair deficient (dMMR) and microsatellite instability-high (MSI-H) cancers are associated with an increased number of somatic mutations, which can render tumors more susceptible to immune checkpoint blockade. However, a comprehensive evaluation of the efficacy profile of immune checkpoint inhibitors in this patient population across multiple cancer types is lacking. This study aims to address this knowledge gap by synthesizing data from phase I-III clinical trials.

METHODS

A systematic search was conducted in PubMed, Embase, the Cochrane Central Register of Controlled Trials, and Google Scholar from inception until June 2024. Eligible studies included randomized controlled trials (RCTs), nonrandomized comparative studies, and single-arm trials investigating immune checkpoint inhibitors in patients with dMMR/MSI-H advanced cancers. The primary outcome was objective response rate (ORR), and the secondary outcomes included disease control rate (DCR), 1-year, 2-year, and 3-year overall survival (OS) and progression-free survival (PFS) rates. Subgroup analyses were conducted for the primary outcome stratified by major study characteristics.

RESULTS

Of the 10 802 identified studies, 19 trials in 25 studies totaling 2052 participants met the inclusion criteria and were included in the meta-analysis. The pooled ORR was 41.7% (95% CI, 35.7-47.7%). The pooled DCR was 68.9% (95% CI, 62.2-75.7%). The pooled 12-month, 24-month, and 36-month OS rates were 29.1% (95% CI, 19.9-38.3%), 35.8% (95% CI, 23.6-48.0%), and 35.8% (95% CI, 23.6-48.0%), respectively. The pooled 12-month, 24-month, and 36-month PFS rates were 46.4% (95% CI, 39.1-53.8%), 67.0% (95% CI, 55.2-78.8%), and 63.1% (95% CI, 37.3-88.9%), respectively.

CONCLUSIONS

The study establishes the therapeutic potential of immune checkpoint inhibitors in dMMR/MSI-H advanced cancers, highlighting the importance of MSI status in this context. Further, head-to-head comparisons are needed to conclusively determine MSI's predictive power relative to proficient mismatch repair/microsatellite stable (pMMR/MSS) tumors.

Efficacy and safety of dostarlimab in combination with chemotherapy in patients with dMMR/MSI-H primary advanced or recurrent endometrial cancer in a phase 3, randomized, placebo-controlled trial (ENGOT-EN6-NSGO/GOG-3031/RUBY)

OBJECTIVES

Part 1 of the RUBY trial (NCT03981796) demonstrated improved survival in patients with primary advanced or recurrent endometrial cancer (EC) treated with dostarlimab plus carboplatin-paclitaxel versus placebo plus carboplatin-paclitaxel. Here, we examine additional efficacy and safety data from patients with mismatch repair deficient/microsatellite instability-high (dMMR/MSI-H) EC in the RUBY trial.

METHODS

Patients were randomized 1:1 to dostarlimab 500 mg or placebo plus carboplatin-paclitaxel every 3 weeks for 6 cycles followed by dostarlimab or placebo every 6 weeks for up to 3 years. In the dMMR/MSI-H population of RUBY Part 1, analysis of progression-free survival by investigator assessment compared with blinded independent central review, sensitivity analyses of the source-verified population compared with the randomized population, and analysis of safety in this population were completed.

RESULTS

In total, 118 patients with dMMR/MSI-H were enrolled in the RUBY trial (53, dostarlimab arm; 65, placebo arm). At the first interim analysis, a 72% reduction in the risk of progression or death (P < 0.0001) was seen with dostarlimab plus carboplatin-paclitaxel by investigator assessment per Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST v1.1), which was consistent with blinded independent central review per RECIST v1.1. Likewise, sensitivity analyses of the source-verified dMMR/MSI-H population compared with the randomized dMMR/MSI-H population were consistent for progression-free survival and overall survival. Safety results seen in the dMMR/MSI-H population were similar to those previously reported for the overall population.

CONCLUSIONS

All primary and secondary efficacy assessments demonstrate the consistent benefit of dostarlimab plus carboplatin-paclitaxel. The improvements seen in survival and the manageable safety profile support the favorable benefit-risk profile for dostarlimab plus carboplatin-paclitaxel in patients with dMMR/MSI-H primary advanced or recurrent EC.

Emerging discoveries on the role of TRIM14: from diseases to immune regulation

TRIM14 is an important member of the TRIM family and is widely expressed in a variety of tissues. Like other members of the TRIM family, TRIM14 is also involved in ubiquitination modifications. TRIM14 was initially reported as an interferon-stimulated gene (ISG). In recent years, many studies have focused on the regulatory role of TRIM14 in signaling pathways such as the PI3K/Akt, NF-κB, and cGAS/STING pathways and revealed its mechanism of action in a variety of pathophysiological processes, and the regulation of TRIM14 has attracted the interest of many researchers as a new direction for the treatment of various diseases. However, there are no reviews on the role of TRIM14 in diseases. In this paper, we will describe the structure of TRIM14, review its role in cancer, cardiovascular disease, cervical spondylosis, inflammation and antiviral immunity, and provide an outlook on future research directions.

Identification of ferroptosis-associated tumor antigens as the potential targets to prevent head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSC) represents nearly 90% of all head and neck tumors. The current treatment modality for HNSC patients primarily involves surgical intervention and radiotherapy, but its therapeutic efficacy remains limited. The mRNA vaccine based on tumor antigens seems promising for cancer treatment. Ferroptosis, a novel form of cell death, is linked to tumor progression and cancer immunotherapy. Nevertheless, the effectiveness of ferroptosis-associated tumor antigens in treating HNSC remains uncertain. In this study, we identified three ferroptosis-associated tumor antigens, namely caveolin1 (CAV1), ferritin heavy chain (FTH1), and solute carrier 3A2 (SLC3A2), as being overexpressed and mutated based on data obtained from The Cancer Genome Atlas and Gene Expression Omnibus databases. These antigens were strongly associated with poor prognosis and infiltration of antigen-presenting cells in HNSC. We further identified two ferroptosis subtypes (FS1 and FS2) with distinct molecular, cellular, and clinical properties to identify antigen-sensitive individuals. Our findings indicate that FS1 exhibits an immune "hot" phenotype, whereas FS2 displays an immune "cold" phenotype. Additionally, differential expression of immunogenic cell death modulators and immune checkpoints was observed between these two immune subtypes. Further exploration of the HNSC's immune landscape revealed significant heterogeneity among individual patients. Our findings suggest that CAV1, FTH1, and SLC3A2 are potential targets to prevent HNSC in FS2 patients. Overall, our research reveals the potential of ferroptosis-associated mRNA vaccines for HNSC and identifies an effective patient population for vaccine treatment.

MSH6-proficient crypt foci in MSH6 constitutional mismatch repair deficiency: reversion of a frameshifted coding microsatellite to its wild-type sequence

The discovery of "mismatch repair deficient (MMRd)-crypt foci" in non-neoplastic intestinal mucosa in Lynch syndrome (LS) has significantly enhanced our understanding of how tumors and tumor immunity form and evolve in LS. In this study, we report the frequent presence of "mismatch repair proficient (MMRp)-crypt foci" in both non-neoplastic and neoplastic intestinal mucosa in a patient with constitutional MMR deficiency (CMMRD), who carried a germline MSH6 pathogenic variant (c.3261dupC) in trans with an MSH6 likely pathogenic variant (c.3724_3726del) and whose tissues were otherwise deficient in MMR globally. The MMRp-crypts occurred at a rate of 1.1/100 crypts in non-neoplastic intestinal mucosa and were readily discernible in adenomas > 1 cm. Sequencing analysis revealed normalization of the MSH6c.3261dupC variant in MMRp-adenoma crypts, indicating reverse frameshifting of the exon 5 C8 microsatellite. Interestingly but not surprisingly, the MMRp-adenoma crypts remained microsatellite-instability-high (MSI-H), and shared oncogenic APC mutations with the background MMRd-adenoma. Contrasting with MSH6-CMMRD, no PMS2-CMMRD individuals (0/5) harbored MMRp-crypts. In conclusion, our study documents distinct MMRp-crypts in MSH6-CMMRD, a phenomenon in keeping with MSH6 being a frequent target of MSI-H due to its coding microsatellite and suggesting that MSH6-CMMRD can potentially serve as a unique model system to further our understanding of MSH6's role in MSI-H tumor formation and evolution. Our findings also bear diagnostic implications; when using MMR immunohistochemistry as an ancillary tool in detecting CMMRD, awareness of these MMRp crypts can help avoid diagnostic pitfalls.

Tumour mutational burden: clinical utility, challenges and emerging improvements

Tumour mutational burden (TMB), defined as the total number of somatic non-synonymous mutations present within the cancer genome, varies across and within cancer types. A first wave of retrospective and prospective research identified TMB as a predictive biomarker of response to immune-checkpoint inhibitors and culminated in the disease-agnostic approval of pembrolizumab for patients with TMB-high tumours based on data from the Keynote-158 trial. Although the applicability of outcomes from this trial to all cancer types and the optimal thresholds for TMB are yet to be ascertained, research into TMB is advancing along three principal avenues: enhancement of TMB assessments through rigorous quality control measures within the laboratory process, including the mitigation of confounding factors such as limited panel scope and low tumour purity; refinement of the traditional TMB framework through the incorporation of innovative concepts such as clonal, persistent or HLA-corrected TMB, tumour neoantigen load and mutational signatures; and integration of TMB with established and emerging biomarkers such as PD-L1 expression, microsatellite instability, immune gene expression profiles and the tumour immune contexture. Given its pivotal functions in both the pathogenesis of cancer and the ability of the immune system to recognize tumours, a profound comprehension of the foundational principles and the continued evolution of TMB are of paramount relevance for the field of oncology.

Analysis of Concordance Between Next-Generation Sequencing Assessment of Microsatellite Instability and Immunohistochemistry-Mismatch Repair From Solid Tumors

PURPOSE

The new CAP guideline published in August 2022 recommends using immunohistochemistry (IHC) to test for mismatch repair defects in gastroesophageal (GE), small bowel (SB), or endometrial carcinoma (EC) cancers over next-generation sequencing assessment of microsatellite instability (NGS-MSI) for immune checkpoint inhibitor (ICI) therapy eligibility and states there is a preference to use IHC over NGS-MSI in colorectal carcinoma (CRC).

METHODS

We assessed the concordance of NGS-MSI and IHC-MMR from a very large cohort across the spectrum of solid tumors.

RESULTS

Of the over 190,000 samples with both NGS-MSI and IHC-MMR about 1,160 were initially flagged as discordant. Of those samples initially flagged as discordant, 50.9% remained discordant after being reviewed by an additional pathologist. This resulted in a final discordance rate of 0.31% (590/191,767). Among CRC, GE, SB and EC, 55.4% of mismatch repair proficient/MSI high (MMRp/MSI-H) tumors had at least one somatic pathogenic mutation in an MMR gene or POLE. Mismatch repair deficient/microsatellite stable (MMRd/MSS) tumors had a significantly lower rate of high tumor mutational burden than MMRp/MSI-H tumors. Across all solid tumors, MMRd/MSI-H tumors had significantly longer overall survival (OS; hazard ratio [HR], 1.47, P < .001) and post-ICI survival (HR, 1.82, P < .001) as compared with MMRp/MSS tumors. The OS for the MMRd/MSS group was slightly worse compared to the MMRp/MSI-H tumors, but this difference was not statistically significant (HR, 0.73, P = .058), with a similar pattern when looking at post-ICI survival (HR, 0.43, P = .155).

CONCLUSION

This study demonstrates that NGS-MSI is noninferior to IHC-MMR and can identify MSI-H tumors that IHC-MMR is unable to detect and conversely IHC-MMR can identify MMRd tumors that NGS-MSI misses.

Differentially expressed circular RNA profiles and comprehensive analysis of circRNA-miRNA-mRNA regulatory network in microsatellite instability-high endometrial cancer

The clinical benefit of anti-programmed cell death protein 1 (PD-1)-based immunotherapy among patients with microsatellite instable (MSI) endometrial cancer (EC) precedes that of microsatellite stable (MSS) EC, the mechanisms of which have not been fully understood. Circular RNAs (circRNAs) were reported to modulate immune evasion in several types of malignancies, while their roles in the immune regulation in EC remain largely unknown. Here, we conducted circRNA array analysis and mRNA-Sequencing of 10 MSI EC samples and 10 MSS EC samples and identified 1083 differentially expressed circRNAs (DE-circRNAs) and 864 differentially expressed mRNAs, based on which we constructed a circRNA-miRNA-mRNA comprehensive network consisting of 35 DE-circRNAs, 56 predicted miRNAs and 24 differentially expressed mRNAs. Finally, we confirmed hsa_circ_0058230 being positively correlated with CD8+ T cells infiltration, suggesting that it might take a part in anti-tumor immunity in EC.

The evolving landscape of tissue-agnostic therapies in precision oncology

Tumor-agnostic therapies represent a paradigm shift in oncology by altering the traditional means of characterizing tumors based on their origin or location. Instead, they zero in on specific genetic anomalies responsible for fueling malignant growth. The watershed moment for tumor-agnostic therapies arrived in 2017, with the US Food and Drug Administration's historic approval of pembrolizumab, an immune checkpoint inhibitor. This milestone marked the marriage of genomics and immunology fields, as an immunotherapeutic agent gained approval based on genomic biomarkers, specifically, microsatellite instability-high or mismatch repair deficiency (dMMR). Subsequently, the approval of NTRK inhibitors, designed to combat NTRK gene fusions prevalent in various tumor types, including pediatric cancers and adult solid tumors, further underscored the potential of tumor-agnostic therapies. The US Food and Drug Administration approvals of targeted therapies (BRAF V600E, RET fusion), immunotherapies (tumor mutational burden ≥10 mutations per megabase, dMMR) and an antibody-drug conjugate (Her2-positive-immunohistochemistry 3+ expression) with pan-cancer efficacy have continued, offering newfound hope to patients grappling with advanced solid tumors that harbor particular biomarkers. In this comprehensive review, the authors delve into the expansive landscape of tissue-agnostic targets and drugs, shedding light on the rationale underpinning this approach, the hurdles it faces, presently approved therapies, voices from the patient advocacy perspective, and the tantalizing prospects on the horizon. This is a welcome advance in oncology that transcends the boundaries of histology and location to provide personalized options.

Clinical status and future prospects of neoadjuvant immunotherapy for localized mismatch repair-deficient cancers: a review

Frameshift mutations accumulate in cancers related to mismatch repair deficiency (dMMR), which has the potential to produce various neoantigens, representing a distinct subset of cancers that respond considerably to immunotherapy. In recent years, robust evidence has supported the first-line application of immunotherapy for patients with metastatic dMMR cancers, which provoked extensive investigations of the feasibility and efficacy of immunotherapy in up-front settings, including neoadjuvant therapy. Several completed trials with small sample sizes suggested that neoadjuvant immunotherapy can achieve an impressively high complete response rate, for the first time offering the potential of systemic therapy to cure cancer without the need for surgical resection. However, a difficult dilemma emerges: clinicians are now facing a selection between the standard of care with good evidence for proficient MMR but suboptimal for dMMR cancers and the emerging immunotherapy with promising results but only based on a limited number of patients with shorter duration of follow-up. This review aims to provide a comprehensive summary of the biological rationale and clinical status of neoadjuvant immunotherapy in patients with dMMR cancers. Furthermore, I elaborate on particular issues that must be taken into consideration for further advancement in the field.

Prophylaxis with abemaciclib delays tumorigenesis in dMMR mice by altering immune responses and reducing immunosuppressive extracellular vesicle secretion

BACKGROUND

The CDK4/6 inhibitor abemaciclib is an FDA-approved agent and induces T-cell-mediated immunity. Previously, we confirmed the therapeutic potential of abemaciclib on mismatch repair-deficient (dMMR) tumors in mice. Here, we applied a prophylactic administration/dosage setting using two preclinical mouse models of dMMR-driven cancer.

METHODS

Mlh1-/- and Msh2loxP/loxP mice received repeated prophylactic applications of abemaciclib mesylate (75 mg/kg bw, per oral) as monotherapy or were left untreated. Blood phenotyping and multiplex cytokine measurements were performed regularly. The tumor microenvironment was evaluated by immunofluorescence and Nanostring-based gene expression profiling. Numbers, size and immune composition and activity of extracellular vesicles (EVs) were studied at the endpoint.

FINDINGS

Prophylactic abemaciclib-administration delayed tumor development and significantly prolonged overall survival in both mouse strains (Mlh1-/-: 50.0 wks vs. control: 33.9 wks; Msh2loxP/loxP;TgTg(Vil1-cre: 58.4 wks vs. control 44.4 wks). In Mlh1-/- mice, pro-inflammatory cytokines (IL-2, IL-6) significantly increased, whereas IL-10 and IL-17A decreased. Circulating and splenic exhausted and regulatory T cell numbers were significantly lower in the abemaciclib groups. Deeper analysis of late-onset tumors revealed activation of the Hedgehog and Notch signaling in Mlh1-/- mice, and activation of the MAPK pathway in Msh2loxP/loxP;TgTg(Vil1-cre mice. Still, arising tumors had fewer infiltrating myeloid-derived suppressor cells (vs. control). Notably, prophylactic abemaciclib-administration prevented secretion of procoagulant EVs but triggered release of immunomodulatory EVs in Mlh1-/- mice.

INTERPRETATION

Prophylactic abemaciclib prolongs survival via global immunomodulation. Prophylactic use of abemaciclib should be considered further for individuals with inherited dMMR.

FUNDING

This work was supported by grants from the German research foundation [DFG grant number: MA5799/2-2] and the Brigitte und Dr. Konstanze Wegener-Stiftung to CM.

The Clinicopathological Features and Prognoses of Lower Uterine Segment Cancer: A Retrospective, Single-Center Cohort Study

Introduction

This study used single-center data to analyze the clinicopathological features of site-specific endometrial cancer.

Methods

Patients with endometrial carcinoma who had undergone surgery at Peking Union Medical College Hospital, China, between March 2016 and January 2022 were enrolled. Clinical information and pathological characteristics were summarized, and microsatellite status was analyzed using the immunohistochemical method. Patient prognoses were measured in terms of the rates of overall survival and progression-free survival.

Results

The mean patient age was 49 years (ranging: from 25 to 76 years old), and there was no difference in clinicopathological features between endometrioid and type II endometrial carcinoma in LUSC. The ER and PR expression ratios were 80.4% and 64.3%, respectively, in this LUSC cohort, and the MMR deficiency ratio was 33.9%, including 39.6% in endometrioid carcinoma and 15.4% in type II endometrial carcinoma. Combined MSH2&MSH6 loss was more common than combined MLH1&PMS2 being unexpressed (16.1% vs 12.5%), and dMMR patients differed significantly from the pMMR group in terms of vascular invasion (P=0.003). The combination of chemotherapy and radiotherapy did not provide a statistically significant improvement in prognosis compared to chemotherapy alone.

Conclusion

The results of this study showed that LUSC patients tended to be younger and their tumors had less expression of hormone markers. The biological behavior of both endometrioid cancer and type II EC may be similar when EC occurs in this area. Furthermore, this type of tumor also showed a higher incidence of vascular invasion, and the combination of chemotherapy and radiotherapy did not provide significant improvement. Thus, successful treatment of LUSC tumors requires aggressive surgical intervention and a more effective postoperative treatment approach.

Genetic and epigenetic instability as an underlying driver of progression and aggressive behavior in IDH-mutant astrocytoma

In recent years, the classification of adult-type diffuse gliomas has undergone a revolution, wherein specific molecular features now represent defining diagnostic criteria of IDH-wild-type glioblastomas, IDH-mutant astrocytomas, and IDH-mutant 1p/19q-codeleted oligodendrogliomas. With the introduction of the 2021 WHO CNS classification, additional molecular alterations are now integrated into the grading of these tumors, given equal weight to traditional histologic features. However, there remains a great deal of heterogeneity in patient outcome even within these established tumor subclassifications that is unexplained by currently codified molecular alterations, particularly in the IDH-mutant astrocytoma category. There is also significant intercellular genetic and epigenetic heterogeneity and plasticity with resulting phenotypic heterogeneity, making these tumors remarkably adaptable and robust, and presenting a significant barrier to the design of effective therapeutics. Herein, we review the mechanisms and consequences of genetic and epigenetic instability, including chromosomal instability (CIN), microsatellite instability (MSI)/mismatch repair (MMR) deficits, and epigenetic instability, in the underlying biology, tumorigenesis, and progression of IDH-mutant astrocytomas. We also discuss the contribution of recent high-resolution transcriptomics studies toward defining tumor heterogeneity with single-cell resolution. While intratumoral heterogeneity is a well-known feature of diffuse gliomas, the contribution of these various processes has only recently been considered as a potential driver of tumor aggressiveness. CIN has an independent, adverse effect on patient survival, similar to the effect of histologic grade and homozygous CDKN2A deletion, while MMR mutation is only associated with poor overall survival in univariate analysis but is highly correlated with higher histologic/molecular grade and other aggressive features. These forms of genomic instability, which may significantly affect the natural progression of these tumors, response to therapy, and ultimately clinical outcome for patients, are potentially measurable features which could aid in diagnosis, grading, prognosis, and development of personalized therapeutics.

Use of PSMA PET/CT to detect prostate cancer metastatic to a preexisting thyroid nodule

Prostate cancer (PCa) seldom metastasizes to the thyroid gland, and only a limited number of cases are documented in the literature. The application of a relatively recent and highly sensitive imaging technique, prostate-specific membrane antigen (PSMA) positron emission tomography-computed tomography (PET/CT), has enhanced the identification of metastatic disease. Nevertheless, as PSMA is expressed in various tissue types, the clinical importance of a PSMA-avid thyroid lesion remains largely uncertain. A minor, yet noteworthy, percentage of these lesions are ultimately determined to be malignant. Here we describe the case of a 70-year-old man with a past medical history of Lynch syndrome who presented to an outpatient oncologic clinic for management of very high risk localized PCa. He developed metastatic recurrence and his disease progressed through several lines of therapy, including immunotherapy and targeted treatments. He was found to have a new, intense PSMA uptake in an existing, previously benign thyroid nodule. Sonographic evaluation revealed changing morphology despite grossly stable size. Repeat biopsy confirmed the unusual finding of PCa metastasis to a known thyroid nodule. The shift in PSMA avidity played a pivotal role in discerning this metastatic deposit. There is a potential risk that such lesions may be inadequately acknowledged. The impact of the patient's Lynch syndrome on this presentation remains uncertain.

Immunotherapy of microsatellite stable colorectal cancer: resistance mechanisms and treatment strategies

In recent years, immunotherapy strategies based on immune checkpoint inhibitors have yielded good efficacy in colorectal cancer (CRC)especially in colorectal cancer with microsatellite instability-high. However, microsatellite-stable (MSS) CRCs account for about 85% of CRCs and are resistant to immunotherapy. Previous studies have shown that compared with MSS CRC, high microsatellite instability CRC possesses a higher frequency of mutations and can generate more neoantigens. Therefore, improving the sensitivity of immunotherapy to MSS CRC is a hot topic which is crucial for the treatment of MSS CRC. This review aims to discuss the factors contributing to MSS CRC insensitivity to immunotherapy and explored potential solutions to overcome immunotherapy resistance.

COP9 signalosome complex is a prognostic biomarker and corresponds with immune infiltration in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is among the most common deadly tumors but still lacks specific biomarkers for diagnosis, prognosis, and treatment guidance. The COP9 signalosome (COPS) is an essential regulator of the ubiquitin conjugation pathway upregulated in various cancers. We evaluated the contributions of COPS subunits to HCC tumorigenesis and their utility for prognosis. We comprehensively evaluated the tumor expression pattern and tumorigenic functions of COPS subunits using The Cancer Genome Atlas (TCGA), The Human Protein Atlas and immunohistochemistry. Kaplan-Meier, Cox regression, ROC curve, and nomogram analyses were used to assess the predictive values of COPS subunits for clinical outcome. Expression levels of COPS subunits were significantly upregulated in HCC tissues, which predicted shorter overall survival (OS). Further, Cox regression analysis identified COPS5, COPS7B, and COPS9 as independent prognostic biomarkers for OS. High mutation rates were also found in COPS subunits. Functional network analysis indicated that COPS and neighboring genes regulate 'protein neddylation', 'protein deneddylation', and 'protein ubiquitination'. The COPS PPI included strong interactions with p53, CUL1/2/3/4, and JUN. Moreover, the correlations between COPS subunit expression levels and tumor immune cell infiltration rates were examined using TIMER, TISIDB, ssGSEA, and ESTIMATE packages. COPS subunits expression levels were positively correlated with specific tumor immune cell infiltration rates, immunoregulator expression levels, and microsatellite instability in HCC. Finally, knockout of COPS6 and COPS9 in HCC cells reduced while overexpression enhanced proliferation rate and metastasis capacity. Our study revealed that COPS potential biomarker for unfavorable HCC prognosis and indicators of immune infiltration, tumorigenicity, and metastasis.

Lynch Syndrome: From Multidisciplinary Management to Precision Prevention

BACKGROUND AND AIMS

Lynch syndrome (LS) is currently one of the most prevalent hereditary cancer conditions, accounting for 3% of all colorectal cancers and for up to 15% of those with DNA mismatch repair (MMR) deficiency, and it was one of the first historically identified. The understanding of the molecular carcinogenesis of LS tumors has progressed significantly in recent years. We aim to review the most recent advances in LS research and explore genotype-based approaches in surveillance, personalized cancer prevention, and treatment strategies.

METHODS

PubMed was searched to identify relevant studies, conducted up to December 2023, investigating molecular carcinogenesis in LS, surveillance strategies, cancer prevention, and treatment in LS tumors.

RESULTS

Multigene panel sequencing is becoming the benchmark in the diagnosis of LS, allowing for the detection of a pathogenic constitutional variant in one of the MMR genes. Emerging data from randomized controlled trials suggest possible preventive roles of resistant starch and/or aspirin in LS. Vaccination with immunogenic frameshift peptides appears to be a promising approach for both the treatment and prevention of LS-associated cancers, as evidenced by pre-clinical and preliminary phase 1/2a studies.

CONCLUSIONS

Although robust diagnostic algorithms, including prompt testing of tumor tissue for MMR defects and referral for genetic counselling, currently exist for suspected LS in CRC patients, the indications for LS screening in cancer-free individuals still need to be refined and standardized. Investigation into additional genetic and non-genetic factors that may explain residual rates of interval cancers, even in properly screened populations, would allow for more tailored preventive strategies.

Beyond PD(L)-1 Blockade in Microsatellite-Instable Cancers: Current Landscape of Immune Co-Inhibitory Receptor Targeting

High microsatellite instability (MSI-H) derives from genomic hypermutability due to deficient mismatch repair function. Colorectal (CRC) and endometrial cancers (EC) are the tumor types that more often present MSI-H. Anti-PD(L)-1 antibodies have been demonstrated to be agnostically effective in patients with MSI-H cancer, but 50-60% of them do not respond to single-agent treatment, highlighting the necessity of expanding their treatment opportunities. Ipilimumab (anti-CTLA4) is the only immune checkpoint inhibitor (ICI) non-targeting PD(L)-1 that has been approved so far by the FDA for MSI-H cancer, namely, CRC in combination with nivolumab. Anti-TIM3 antibody LY3321367 showed interesting clinical activity in combination with anti-PDL-1 antibody in patients with MSI-H cancer not previously treated with anti-PD(L)-1. In contrast, no clinical evidence is available for anti-LAG3, anti-TIGIT, anti-BTLA, anti-ICOS and anti-IDO1 antibodies in MSI-H cancers, but clinical trials are ongoing. Other immunotherapeutic strategies under study for MSI-H cancers include vaccines, systemic immunomodulators, STING agonists, PKM2 activators, T-cell immunotherapy, LAIR-1 immunosuppression reversal, IL5 superagonists, oncolytic viruses and IL12 partial agonists. In conclusion, several combination therapies of ICIs and novel strategies are emerging and may revolutionize the treatment paradigm of MSI-H patients in the future. A huge effort will be necessary to find reliable immune biomarkers to personalize therapeutical decisions.

Immune checkpoint inhibitors with chemotherapy for primary advanced mismatch repair-deficient endometrial cancer: A cost-effectiveness analysis

OBJECTIVE

The addition of immune checkpoint inhibitors (ICIs), pembrolizumab or dostarlimab, to paclitaxel and carboplatin (TC) has shown better response rates and survival outcomes for patients with primary advanced mismatch repair-deficient (MMRd) endometrial cancer (EC) in NRG-GY018 and RUBY, respectively. Nonetheless, the high cost of ICIs remains a major concern when implementing this strategy in the real world. This study aimed to determine the cost-effectiveness of pembrolizumab and dostarlimab with chemotherapy compared to TC for primary advanced MMRd EC.

METHODS

We developed a Markov model including 6600 patients with primary advanced MMRd EC to simulate treatment outcomes. The initial decision points in the model were treatment with pembrolizumab with TC (PEM-TC), dostarlimab with TC (DOS-TC), and TC. Model probabilities, costs, and health utility values were derived with assumptions from published literature. Effectiveness was determined as average quality-adjusted life years (QALYs) gained. The primary outcome was the incremental cost-effectiveness ratio (ICER).

RESULTS

TC was the least costly strategy, whereas PEM-TC was the most effective strategy for primary advanced MMRd EC. TC was cost-effective based on a willingness-to-pay (WTP) threshold of $100,000/QALY compared with PEM-TC (ICER, $377,718/QALY), and DOS-TC exhibited absolute dominance (ICER, $401,859/QALY). PEM-TC was cost-effective when the cost of pembrolizumab 200 mg was reduced to $4361 (61% reduction). PEM-TC was selected in 16.5% with a WTP threshold of $300,000/QALY, but in <1% with a WTP threshold range of $100,000-200,000/QALY.

CONCLUSION

PEM-TC can become cost-effective for primary advanced MMRd EC when the cost of pembrolizumab substantially decreases.

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.

FOXP3 recognizes microsatellites and bridges DNA through multimerization

FOXP3 is a transcription factor that is essential for the development of regulatory T cells, a branch of T cells that suppress excessive inflammation and autoimmunity1-5. However, the molecular mechanisms of FOXP3 remain unclear. Here we here show that FOXP3 uses the forkhead domain-a DNA-binding domain that is commonly thought to function as a monomer or dimer-to form a higher-order multimer after binding to TnG repeat microsatellites. The cryo-electron microscopy structure of FOXP3 in a complex with T3G repeats reveals a ladder-like architecture, whereby two double-stranded DNA molecules form the two 'side rails' bridged by five pairs of FOXP3 molecules, with each pair forming a 'rung'. Each FOXP3 subunit occupies TGTTTGT within the repeats in a manner that is indistinguishable from that of FOXP3 bound to the forkhead consensus motif (TGTTTAC). Mutations in the intra-rung interface impair TnG repeat recognition, DNA bridging and the cellular functions of FOXP3, all without affecting binding to the forkhead consensus motif. FOXP3 can tolerate variable inter-rung spacings, explaining its broad specificity for TnG-repeat-like sequences in vivo and in vitro. Both FOXP3 orthologues and paralogues show similar TnG repeat recognition and DNA bridging. These findings therefore reveal a mode of DNA recognition that involves transcription factor homomultimerization and DNA bridging, and further implicates microsatellites in transcriptional regulation and diseases.

Prognostic value of primary tumor location in colorectal cancer: an updated meta-analysis

The clinical, histological, and molecular differences between right-sided colon cancer (RCC) and left-sided colon cancer (RCC) have received considerable attention. Over the past decade, many articles have been published concerning the association between primary tumor location (PTL) of colorectal cancer and survival outcomes. Therefore, there is a growing need for an updated meta-analysis integrating the outcomes of recent studies to determine the prognostic role of right vs left-sidedness of PTL in patients with colorectal cancer. We conducted a comprehensive database review using PubMed, SCOPUS, and Cochrane library databases from February 2016 to March 2023 for prospective or retrospective studies reporting data on overall survival (OS) and cancer-specific survival (CSS) of RCC compared with LCC. A total of 60 cohort studies comprising 1,494,445 patients were included in the meta-analysis. We demonstrated that RCC is associated with a significantly increased risk of death compared with LCC by 25% (hazard ratio (HR), 1.25; 95% confidence interval (CI), 1.19-1.31; I2 = 78.4%; Z = 43.68). Results showed that patients with RCC have a worse OS compared with LCC only in advanced stages (Stage III: HR, 1.275; 95% CI 1.16-1.4; P = 0.0002; I2 = 85.8%; Stage IV: HR, 1.34; 95% CI 1.25-1.44; P < 0.0001; I2 = 69.2%) but not in primary stages (Stage I/II: HR, 1.275; 95% CI 1.16-1.4; P = 0.0002; I2 = 85.8%). Moreover, a meta-analysis of 13 studies including 812,644 patients revealed that there is no significant difference in CSS between RCC and LCC (HR, 1.121; 95% CI 0.97-1.3; P = 0.112). Findings from the present meta-analysis highlight the importance of PTL in clinical decision-making for patients with CRC, especially in advanced stages. We provide further evidence supporting the hypothesis that RCC and LCC are distinct disease entities that should be managed differently.

PD-1/PD-L1 inhibitors plus carboplatin and paclitaxel compared with carboplatin and paclitaxel in primary advanced or recurrent endometrial cancer: a systematic review and meta-analysis of randomized clinical trials

BACKGROUND

Paclitaxel and carboplatin is the standard chemotherapy for the treatment of advanced or recurrent endometrial cancer. However, the benefit of adding programmed cell death 1 (PD-1)/programmed death ligand 1 (PD-L1) inhibitors to chemotherapy is still unclear.

METHOD

We searched PubMed, Scopus, Cochrane, and Web of Science databases for randomized controlled trials that investigated PD-1/PD-L1 inhibitors plus carboplatin and paclitaxel compared with carboplatin and paclitaxel in primary advanced or recurrent endometrial cancer. We computed hazard ratios (HRs) or risk ratios (RRs) for binary endpoints, with 95% confidence intervals (CIs). We used DerSimonian and Laird random-effect models for all endpoints. Heterogeneity was assessed using I2 statistics. R, version 4.2.3, was used for statistical analyses.

RESULTS

A total of three studies and 1,431 patients were included. Compared with carboplatin plus paclitaxel-based chemotherapy, progression-free survival (PFS) rate (HR 0.32; 95% CI 0.23-0.44; p < 0.001) and overall survival (OS) at 30 months (RR 3.13; 95% CI 1.26-7.78; p = 0.01) were significant in favor of the PD-1/PD-L1 inhibitors plus carboplatin and paclitaxel group in the mismatch repair-deficient subgroup. However, there were no significant differences in the mismatch repair-proficient subgroup for PFS (HR 0.74; 95% CI 0.50-1.08; p = 0.117) or OS at 30 months (RR 2.24; 95% CI 0.79-6.39; p = 0.13).

CONCLUSION

Immunotherapy plus carboplatin-paclitaxel increased significantly PFS and OS among patients with advanced or recurrent endometrial cancer, with a significant benefit in the mismatch repair-deficient and high microsatellite instability population.

FoxP3 recognizes microsatellites and bridges DNA through multimerization

FoxP3 is a transcription factor (TF) essential for development of regulatory T cells (Tregs), a branch of T cells that suppress excessive inflammation and autoimmunity 1-5 . Molecular mechanisms of FoxP3, however, remain elusive. We here show that FoxP3 utilizes the Forkhead domain--a DNA binding domain (DBD) that is commonly thought to function as a monomer or dimer--to form a higher-order multimer upon binding to T n G repeat microsatellites. A cryo-electron microscopy structure of FoxP3 in complex with T 3 G repeats reveals a ladder-like architecture, where two double-stranded DNA molecules form the two "side rails" bridged by five pairs of FoxP3 molecules, with each pair forming a "rung". Each FoxP3 subunit occupies TGTTTGT within the repeats in the manner indistinguishable from that of FoxP3 bound to the Forkhead consensus motif (FKHM; TGTTTAC). Mutations in the "intra-rung" interface impair T n G repeat recognition, DNA bridging and cellular functions of FoxP3, all without affecting FKHM binding. FoxP3 can tolerate variable "inter-rung" spacings, explaining its broad specificity for T n G repeat-like sequences in vivo and in vitro . Both FoxP3 orthologs and paralogs show similar T n G repeat recognition and DNA bridging. These findings thus reveal a new mode of DNA recognition that involves TF homo-multimerization and DNA bridging, and further implicates microsatellites in transcriptional regulation and diseases.

Outcomes of dostarlimab versus chemotherapy in post-platinum patients with recurrent/advanced endometrial cancer: data from the GARNET trial and the National Cancer Registration Service in England

OBJECTIVES

Immune checkpoint inhibitors have emerged as novel treatment options in patients with endometrial cancer. In this study we aimed to compare the survival outcomes of patients with recurrent or advanced endometrial cancer. These patients had received dostarlimab after platinum-based chemotherapy in the single-arm, Phase I GARNET trial. We compared them with a matched indirect real-world cohort.

METHODS

The real-world cohort was established using National Cancer Registration and Analysis Service data, with five treatment-specific real-world sub-cohorts identified. To compare clinical outcomes between the GARNET trial and real-world cohorts, we performed matching-adjusted indirect comparisons. We used prognostic variables to create matching scenarios, including scenario 1 that incorporated grade, histology, and platinum-based chemotherapy number; scenario 2 that considered histology and platinum-based chemotherapy number; and scenario 3 that included race/ethnicity, stage at diagnosis, histology, and prior surgery. Overall survival was defined as the time between the first dostarlimab dose or second-line real-world treatment and death. Adjusted hazard ratios for matching-adjusted indirect comparisons were estimated via weighted Cox proportional-hazards models. Progression-free survival, using time-to-next treatment as a proxy for real-world cohorts, was summarized descriptively.

RESULTS

Distribution of baseline characteristics that were matched was similar between the GARNET cohort (n=153) and the real-world cohort (n=999). The most common International Federation of Gynecology and Obstetrics (FIGO) stage in both cohorts was stage III/IV (n=88; 57.5% and n=778; 77.9%, respectively), with endometroid histology predominating in the GARNET cohort (n=121; 79.1%) and non-endometrioid the predominant form in the real-world cohort (n=575; 57.6%). The median overall survival for dostarlimab was longer (range 27.1-40.5 months [95% confidence interval (CI) 6.4-non-estimable and 19.4-non-estimable]) both before and after matching for all scenarios compared with the real-world cohort (10.3 months). Across all matching scenarios, patients in the GARNET cohort had a decreased risk of death, with a HR for overall survival of 0.32 (p<0.0001) before matching, as compared with the overall real-world cohort and most treatment-specific real-world cohorts. For all three scenarios, progression-free survival rates at 12 and 18 months were higher for patients on dostarlimab compared with the real-world cohort (0.48 and 0.43 respectively before matching in the GARNET cohort vs 0.28 and 0.16 respectively in the real-world cohort; using time to next treatment as proxy). The effective sample size for scenario 1 was low when compared with the other scenarios (scenario 1: n=18; scenario 2: n=62; scenario 3: n=67).

CONCLUSION

In this adjusted indirect dataset, patients with recurrent/advanced mismatch repair deficient/microsatellite instability-high endometrial cancer post-platinum-based chemotherapy who received dostarlimab in the GARNET trial had significantly improved overall survival compared with patients receiving current second-line treatment in England.

Antitumor Activity and Safety of Dostarlimab Monotherapy in Patients With Mismatch Repair Deficient Solid Tumors: A Nonrandomized Controlled Trial

Importance

Mismatch repair deficiency (dMMR) occurs in various cancers, and these tumors are attractive candidates for anti-programmed cell death 1 therapies, such as dostarlimab, a recently approved immune checkpoint inhibitor.

Objective

To assess the antitumor activity and safety of dostarlimab in patients with advanced or recurrent dMMR solid tumors.

Design, Setting, And Participants

The GARNET trial was a phase 1, open-label, single-group, multicenter study that began enrolling May 8, 2017. Participants had advanced or recurrent dMMR and microsatellite instability-high (MSI-H) or polymerase epsilon (POLE)-altered solid tumors. The data cut for this interim analysis was from November 1, 2021, with median follow-up of 27.7 months.

Interventions

Patients received 500 mg of dostarlimab intravenously every 3 weeks for 4 doses, then 1000 mg every 6 weeks until disease progression, discontinuation, or withdrawal.

Main Outcomes and Measures

The primary objective was to evaluate objective response rate and duration of response in patients with dMMR solid tumors by blinded independent central review using Response Evaluation Criteria in Solid Tumors, version 1.1.

Results

The efficacy population included 327 patients (median [range] age, 63 [24-85] years; 235 [71.9%] female; 7 [2.1%] Asian, 6 [1.8%] Black, and 206 [63.0%] White patients), with 141 patients (43.1%) with dMMR endometrial cancer, 105 patients (32.1%) with dMMR colorectal cancer, and 81 patients (24.8%) with other dMMR tumor types. All patients had at least 1 previous line of therapy. Objective response rate assessed per blinded independent central review for dMMR solid tumors was 44.0% (95% CI, 38.6% to 49.6%). Median duration of response was not reached (range, ≥1.18 to ≥47.21 months); 72.2% of responders (104 of 144) had a response lasting 12 or more months. Median progression-free survival was 6.9 months (95% CI, 4.2 to 13.6 months); probability of progression-free survival at 24 months was 40.6% (95% CI, 35.0% to 46.1%). Median overall survival was not reached (95% CI, 31.6 months to not reached). The most frequent immune-related adverse events were hypothyroidism (25 [6.9%]), alanine aminotransferase increase (21 [5.8%]), and arthralgia (17 [4.7%]). No new safety concerns were identified.

Conclusions And Relevance

In this nonrandomized controlled trial, dostarlimab was a well-tolerated treatment option with rapid, robust, and durable antitumor activity in patients with diverse dMMR solid tumors. These findings suggest that dostarlimab provides meaningful long-term benefit in a population with high unmet need.

Trial Registration

ClinicalTrials.gov Identifier: NCT02715284.

Advances in vaccine development for cancer prevention and treatment in Lynch Syndrome

Lynch Syndrome (LS) is one of the most common hereditary cancer syndromes, and is caused by mutations in one of the four DNA mismatch repair (MMR) genes, namely MLH1, MSH2, MSH6 and PMS2. Tumors developed by LS carriers display high levels of microsatellite instability, which leads to the accumulation of large numbers of mutations, among which frameshift insertion/deletions (indels) within microsatellite (MS) loci are the most common. As a result, MMR-deficient (MMRd) cells generate increased rates of tumor-specific neoantigens (neoAgs) that can be recognized by the immune system to activate cancer cell killing. In this context, LS is an ideal disease to leverage immune-interception strategies. Therefore, the identification of these neoAgs is an ongoing effort for the development of LS cancer preventive vaccines. In this review, we summarize the computational methods used for in silico neoAg prediction, including their challenges, and the experimental techniques used for in vitro validation of their immunogenicity. In addition, we outline results from past and on-going vaccine clinical trials and highlight avenues for improvement and future directions.

Subclonal accumulation of immune escape mechanisms in microsatellite instability-high colorectal cancers

BACKGROUND

Intratumor heterogeneity (ITH) in microsatellite instability-high (MSI-H) colorectal cancer (CRC) has been poorly studied. We aimed to clarify how the ITH of MSI-H CRCs is generated in cancer evolution and how immune selective pressure affects ITH.

METHODS

We reanalyzed public whole-exome sequencing data on 246 MSI-H CRCs. In addition, we performed a multi-region analysis from 6 MSI-H CRCs. To verify the process of subclonal immune escape accumulation, a novel computational model of cancer evolution under immune pressure was developed.

RESULTS

Our analysis presented the enrichment of functional genomic alterations in antigen-presentation machinery (APM). Associative analysis of neoantigens indicated the generation of immune escape mechanisms via HLA alterations. Multiregion analysis revealed the clonal acquisition of driver mutations and subclonal accumulation of APM defects in MSI-H CRCs. Examination of variant allele frequencies demonstrated that subclonal mutations tend to be subjected to selective sweep. Computational simulations of tumour progression with the interaction of immune cells successfully verified the subclonal accumulation of immune escape mutations and suggested the efficacy of early initiation of an immune checkpoint inhibitor (ICI) -based treatment.

CONCLUSIONS

Our results demonstrate the heterogeneous acquisition of immune escape mechanisms in MSI-H CRCs by Darwinian selection, providing novel insights into ICI-based treatment strategies.

Tumor Vaccines: Unleashing the Power of the Immune System to Fight Cancer

This comprehensive review delves into the rapidly evolving arena of cancer vaccines. Initially, we examine the intricate constitution of the tumor microenvironment (TME), a dynamic factor that significantly influences tumor heterogeneity. Current research trends focusing on harnessing the TME for effective tumor vaccine treatments are also discussed. We then provide a detailed overview of the current state of research concerning tumor immunity and the mechanisms of tumor vaccines, describing the complex immunological processes involved. Furthermore, we conduct an exhaustive analysis of the contemporary research landscape of tumor vaccines, with a particular focus on peptide vaccines, DNA/RNA-based vaccines, viral-vector-based vaccines, dendritic-cell-based vaccines, and whole-cell-based vaccines. We analyze and summarize these categories of tumor vaccines, highlighting their individual advantages, limitations, and the factors influencing their effectiveness. In our survey of each category, we summarize commonly used tumor vaccines, aiming to provide readers with a more comprehensive understanding of the current state of tumor vaccine research. We then delve into an innovative strategy combining cancer vaccines with other therapies. By studying the effects of combining tumor vaccines with immune checkpoint inhibitors, radiotherapy, chemotherapy, targeted therapy, and oncolytic virotherapy, we establish that this approach can enhance overall treatment efficacy and offset the limitations of single-treatment approaches, offering patients more effective treatment options. Following this, we undertake a meticulous analysis of the entire process of personalized cancer vaccines, elucidating the intricate process from design, through research and production, to clinical application, thus helping readers gain a thorough understanding of its complexities. In conclusion, our exploration of tumor vaccines in this review aims to highlight their promising potential in cancer treatment. As research in this field continues to evolve, it undeniably holds immense promise for improving cancer patient outcomes.

Colorectal Cancer Immunotherapy: State of the Art and Future Directions

Cancer immunotherapy has become an indispensable mode of treatment for a multitude of solid tumor cancers. Colorectal cancer (CRC) has been one of the many cancer types to benefit from immunotherapy, especially in advanced disease where standard treatment fails to prevent recurrence or results in poor survival. The efficacy of immunotherapy in CRC has not been without challenge, as early clinical trials observed dismal responses in unselected CRC patients treated with checkpoint inhibitors. Many studies and clinical trials have since refined immunotherapies available for CRC, solidifying immunotherapy as a powerful asset for CRC treatment. This review article examines CRC immunotherapies, from their foundation, through emerging avenues for improvement, to future directions.

TIME for Bugs: The Immune Microenvironment and Microbes in Precancer

Major advances in our understanding of the tumor immune microenvironment (TIME) in established cancer have been made, including the influence of host-intrinsic (host genomics) and -extrinsic factors (such as diet and the microbiome) on treatment response. Nonetheless, the immune and microbiome milieu across the spectrum of precancerous tissue and early neoplasia is a growing area of interest. There are emerging data describing the contribution of the immune microenvironment and microbiota on benign and premalignant tissues, with opportunities to target these factors in cancer prevention and interception. Throughout this review, we provide rationale for not only the critical need to further elucidate the premalignant immune microenvironment, but also for the utility of pharmacologic and lifestyle interventions to alter the immune microenvironment of early lesions to reverse carcinogenesis. Novel research methodologies, such as implementing spatial transcriptomics and proteomics, in combination with innovative sampling methods will advance precision targeting of the premalignant immune microenvironment. Additional studies defining the continuum of immune and microbiome evolution, which emerges in parallel with tumor development, will provide novel opportunities for cancer interception at the earliest steps in carcinogenesis.

From organ preservation to selective surgery: How immunotherapy changes colorectal surgery?

The emergence of immunotherapy has revolutionized the traditional treatment paradigm of colorectal cancer (CRC). Among them, immune checkpoint blockade has become the first-line treatment for metastatic colorectal cancer (mCRC) and has made significant progress in the treatment of locally advanced colorectal cancer (LACRC). We reviewed a series of clinical trials that have made breakthrough progress. We will emphasize the breakthrough progress in achieving organ preservation in patients with high microsatellite instability or DNA mismatch repair deficiency (MSI-H/dMMR), and based on this, we propose the concept of selective surgery, which includes selectively removing or preserving lymph nodes, with the aim of proving our idea through more research in the future.

Serum matrix metalloproteinase-7: a potential biomarker in patients with Lynch Syndrome

BACKGROUND AND AIMS

The expression of tissue and serum matrix metalloproteinase-7 (MMP-7) was shown to be elevated both in colon cancer and dysplastic lesions. We aimed to evaluate, for the first time, its role as a diagnostic marker in Lynch syndrome (LS) carriers, a hereditary syndrome with predisposition to colon cancer.

METHODS

This was a case control study. Baseline serum MMP-7 levels were determined by ELISA in 40 colon cancer patients, 62 LS-carriers and 60 healthy controls. Retrieved data from medical files included demographics, background diseases, clinical data regarding tumor characteristics and genetic data. We assessed the association of serum MMP-7 levels with different variables in the study cohort using linear regression model adjusted for potential confounders.

RESULTS

In crude analysis, serum MMP-7 levels were significantly higher in colon cancer group compared to LS-carriers and controls [median (IQR) 4.1 ng/ml (2.7-6.0), 2.3 ng/ml (1.7-3.1), 2.5 ng/ml (1.5-3.7), respectively; p value - p < 0.001) while there was no difference between the two last groups (p value = 0.583). However, after adjusting for age and gender, LS-carriers' patients had 18% higher concentrations of serum MMP-7 compared to healthy controls (p value = 0.037), while colon cancer patients had 50% higher serum MMP-7 level in comparison to healthy controls (p value < 0.001). Additionally, age was positively associated with higher serum MMP-7 levels across all study groups (r = 0.67, p value < 0.001). In contrast, no correlation was observed between serum MMP-7 and either tumor staging and gene mutation.

CONCLUSIONS

Age-adjusted serum MMP-7 levels in asymptomatic LS carriers are higher than its levels in healthy population. While in colon cancer, MMP-7 higher level probably reflects the tumor burden and may have a prognostic effect, its significance and clinical applicability as a biomarker for tumorigenesis in LS is less clear and should be elucidated.

Targeting TCF19 sensitizes MSI endometrial cancer to anti-PD-1 therapy by alleviating CD8+ T cell exhaustion via TRIM14-IFN-β axis

Immune checkpoint blockade (ICB) therapies display clinical efficacy in microsatellite instable (MSI) endometrial cancer (EC) treatment, the key mechanism of which is reversing T cell exhaustion and restoration of anti-tumor immunity. Here, we demonstrate that transcription factor 19 (TCF19), one of the most significantly differentially expressed genes between MSI and microsatellite stable (MSS) patients in The Cancer Genome Atlas (TCGA)-EC cohort, is associated with poor prognosis and immune exhaustion signature. Specifically, TCF19 is significantly elevated in MSI EC, which in turn promotes tripartite motif-containing 14 (TRIM14) transcription and correlates with hyperactive signaling of the TANK-binding kinase 1 (TBK1)-interferon regulatory factor 3 (IRF3)-interferon β (IFN-β) pathway. The TCF19-TRIM14 axis promotes tumorigenicity under non-immunological background, and the enhanced downstream secretion of IFN-β facilitates CD8+ T cell exhaustion through cell differentiation reprogramming. Finally, using humanized models, we show that a combination of TCF19 inhibition and ICB therapy demonstrates more effective anti-tumor responses. Together, our study indicates that targeting TCF19 is a potent strategy for alleviating CD8+ T cell exhaustion and synergizing with ICB in tumor treatment.

Biomarkers for immune checkpoint inhibition in sarcomas - are we close to clinical implementation?

Sarcomas are a group of diverse and complex cancers of mesenchymal origin that remains poorly understood. Recent developments in cancer immunotherapy have demonstrated a potential for better outcomes with immune checkpoint inhibition in some sarcomas compared to conventional chemotherapy. Immune checkpoint inhibitors (ICIs) are key agents in cancer immunotherapy, demonstrating improved outcomes in many tumor types. However, most patients with sarcoma do not benefit from treatment, highlighting the need for identification and development of predictive biomarkers for response to ICIs. In this review, we first discuss United States (US) Food and Drug Administration (FDA)-approved and European Medicines Agency (EMA)-approved biomarkers, as well as the limitations of their use in sarcomas. We then review eight potential predictive biomarkers and rationalize their utility in sarcomas. These include gene expression signatures (GES), circulating neutrophil-to-lymphocyte ratio (NLR), indoleamine 2,3-dioxygenase (IDO), lymphocyte activation gene 3 (LAG-3), T cell immunoglobin and mucin domain-containing protein 3 (TIM-3), TP53 mutation status, B cells, and tertiary lymphoid structures (TLS). Finally, we discuss the potential for TLS as both a predictive and prognostic biomarker for ICI response in sarcomas to be implemented in the clinic.

Lynch Syndrome Biopathology and Treatment: The Potential Role of microRNAs in Clinical Practice

Lynch syndrome (LS), also known as Hereditary Non-Polyposis Colorectal Cancer (HNPCC), is an autosomal dominant cancer syndrome which causes about 2-3% of cases of colorectal carcinoma. The development of LS is due to the genetic and epigenetic inactivation of genes involved in the DNA mismatch repair (MMR) system, causing an epiphenomenon known as microsatellite instability (MSI). Despite the fact that the genetics of the vast majority of MSI-positive (MSI+) cancers can be explained, the etiology of this specific subset is still poorly understood. As a possible new mechanism, it has been recently demonstrated that the overexpression of certain microRNAs (miRNAs, miRs), such as miR-155, miR-21, miR-137, can induce MSI or modulate the expression of the genes involved in LS pathogenesis. MiRNAs are small RNA molecules that regulate gene expression at the post-transcriptional level by playing a critical role in the modulation of key oncogenic pathways. Increasing evidence of the link between MSI and miRNAs in LS prompted a deeper investigation into the miRNome involved in these diseases. In this regard, in this study, we discuss the emerging role of miRNAs as crucial players in the onset and progression of LS as well as their potential use as disease biomarkers and therapeutic targets in the current view of precision medicine.

Depicting the landscape of gut microbial-metabolic interaction and microbial-host immune heterogeneity in deficient and proficient DNA mismatch repair colorectal cancers

BACKGROUND

Accumulating evidence has indicated the role of gut microbiota in remodeling host immune signatures, but various interplays underlying colorectal cancers (CRC) with deficient DNA mismatch repair (dMMR) and proficient DNA mismatch repair (pMMR) remain poorly understood. This study aims to decipher the gut microbiome-host immune interactions between dMMR and pMMR CRC.

METHOD

We performed metagenomic sequencing and metabolomic analysis of fecal samples from a cohort encompassing 455 participants, including 21 dMMR CRC, 207 pMMR CRC, and 227 healthy controls. Among them, 50 tumor samples collected from 5 dMMR CRC and 45 pMMR CRC were conducted bulk RNA sequencing.

RESULTS

Pronounced microbiota and metabolic heterogeneity were identified with 211 dMMR-enriched species, such as Fusobacterium nucleatum and Akkermansia muciniphila, 2 dMMR-depleted species, such as Flavonifractor plautii, 13 dMMR-enriched metabolites, such as retinoic acid, and 77 dMMR-depleted metabolites, such as lactic acid, succinic acid, and 2,3-dihydroxyvaleric acid. F. plautii was enriched in pMMR CRC and it was positively associated with fatty acid degradation, which might account for the accumulation of dMMR-depleted metabolites classified as short chain organic acid (lactic acid, succinic acid, and 2,3-dihydroxyvaleric acid) in pMMR CRC. The microbial-metabolic association analysis revealed the characterization of pMMR CRC as the accumulation of lactate induced by the depletion of specific gut microbiota which was negatively associated with antitumor immune, whereas the nucleotide metabolism and peptide degradation mediated by dMMR-enriched species characterized dMMR CRC. MMR-specific metabolic landscapes were related to distinctive immune features, such as CD8+ T cells, dendritic cells and M2-like macrophages.

CONCLUSIONS

Our mutiomics results delineate a heterogeneous landscape of microbiome-host immune interactions within dMMR and pMMR CRC from aspects of bacterial communities, metabolic features, and correlation with immunocyte compartment, which infers the underlying mechanism of heterogeneous immune responses.

Biomaterial-enabled therapeutic modulation of cGAS-STING signaling for enhancing antitumor immunity

cGAS-STING signaling is a central component in the therapeutic action of most existing cancer therapies. The accumulated knowledge of tumor immunoregulatory network in recent years has spurred the development of cGAS-STING agonists for tumor treatment as an effective immunotherapeutic strategy. However, the clinical translation of these agonists is thus far unsatisfactory because of the low immunostimulatory efficacy and unrestricted side effects under clinically relevant conditions. Interestingly, the rational integration of biomaterial technology offers a promising approach to overcome these limitations for more effective and safer cGAS-STING-mediated tumor therapy. Herein, we first outline the cGAS-STING signaling axis and generally discuss its association with tumors. We then symmetrically summarize the recent progress in those biomaterial-based cGAS-STING agonism strategies to generate robust antitumor immunity, categorized by the chemical nature of those cGAS-STING stimulants and carrier substrates. Finally, a perspective is provided to discuss the existing challenges and potential opportunities in cGAS-STING modulation for tumor therapy.

Dostarlimab for Primary Advanced or Recurrent Endometrial Cancer

BACKGROUND

Dostarlimab is an immune-checkpoint inhibitor that targets the programmed cell death 1 receptor. The combination of chemotherapy and immunotherapy may have synergistic effects in the treatment of endometrial cancer.

METHODS

We conducted a phase 3, global, double-blind, randomized, placebo-controlled trial. Eligible patients with primary advanced stage III or IV or first recurrent endometrial cancer were randomly assigned in a 1:1 ratio to receive either dostarlimab (500 mg) or placebo, plus carboplatin (area under the concentration-time curve, 5 mg per milliliter per minute) and paclitaxel (175 mg per square meter of body-surface area), every 3 weeks (six cycles), followed by dostarlimab (1000 mg) or placebo every 6 weeks for up to 3 years. The primary end points were progression-free survival as assessed by the investigator according to Response Evaluation Criteria in Solid Tumors (RECIST), version 1.1, and overall survival. Safety was also assessed.

RESULTS

Of the 494 patients who underwent randomization, 118 (23.9%) had mismatch repair-deficient (dMMR), microsatellite instability-high (MSI-H) tumors. In the dMMR-MSI-H population, estimated progression-free survival at 24 months was 61.4% (95% confidence interval [CI], 46.3 to 73.4) in the dostarlimab group and 15.7% (95% CI, 7.2 to 27.0) in the placebo group (hazard ratio for progression or death, 0.28; 95% CI, 0.16 to 0.50; P<0.001). In the overall population, progression-free survival at 24 months was 36.1% (95% CI, 29.3 to 42.9) in the dostarlimab group and 18.1% (95% CI, 13.0 to 23.9) in the placebo group (hazard ratio, 0.64; 95% CI, 0.51 to 0.80; P<0.001). Overall survival at 24 months was 71.3% (95% CI, 64.5 to 77.1) with dostarlimab and 56.0% (95% CI, 48.9 to 62.5) with placebo (hazard ratio for death, 0.64; 95% CI, 0.46 to 0.87). The most common adverse events that occurred or worsened during treatment were nausea (53.9% of the patients in the dostarlimab group and 45.9% of those in the placebo group), alopecia (53.5% and 50.0%), and fatigue (51.9% and 54.5%). Severe and serious adverse events were more frequent in the dostarlimab group than in the placebo group.

CONCLUSIONS

Dostarlimab plus carboplatin-paclitaxel significantly increased progression-free survival among patients with primary advanced or recurrent endometrial cancer, with a substantial benefit in the dMMR-MSI-H population. (Funded by GSK; RUBY ClinicalTrials.gov number, NCT03981796.).

Microsatellite Instability and Immune Response: From Microenvironment Features to Therapeutic Actionability-Lessons from Colorectal Cancer

Microsatellite instability (MSI) can be found in 15-20% of all colorectal cancers (CRC) and is the key feature of a defective DNA mismatch repair (MMR) system. Currently, MSI has been established as a unique and pivotal biomarker in the diagnosis, prognosis, and treatment of CRC. MSI tumors display a strong lymphocytic activation and a shift toward a tumoral microenvironment restraining metastatic potential and ensuing in a high responsiveness to immunotherapy of MSI CRC. Indeed, neoplastic cells with an MMR defect overexpress several immune checkpoint proteins, such as programmed death-1 (PD-1) and programmed death-ligand 1(PD-L1), that can be pharmacologically targeted, allowing for the revival the cytotoxic immune response toward the tumor. This review aims to illustrate the role of MSI in the tumor biology of colorectal cancer, focusing on the immune interactions with the microenvironment and their therapeutic implications.

Genomic hallmarks and therapeutic implications of G0 cell cycle arrest in cancer

BACKGROUND

Therapy resistance in cancer is often driven by a subpopulation of cells that are temporarily arrested in a non-proliferative G0 state, which is difficult to capture and whose mutational drivers remain largely unknown.

RESULTS

We develop methodology to robustly identify this state from transcriptomic signals and characterise its prevalence and genomic constraints in solid primary tumours. We show that G0 arrest preferentially emerges in the context of more stable, less mutated genomes which maintain TP53 integrity and lack the hallmarks of DNA damage repair deficiency, while presenting increased APOBEC mutagenesis. We employ machine learning to uncover novel genomic dependencies of this process and validate the role of the centrosomal gene CEP89 as a modulator of proliferation and G0 arrest capacity. Lastly, we demonstrate that G0 arrest underlies unfavourable responses to various therapies exploiting cell cycle, kinase signalling and epigenetic mechanisms in single-cell data.

CONCLUSIONS

We propose a G0 arrest transcriptional signature that is linked with therapeutic resistance and can be used to further study and clinically track this state.