[Epidemiology of microsatellite instability across solid neoplasms]

Case report: Microsatellite instability determination is not always black and white in Lynch syndrome diagnosis

Introduction

Microsatellite instability (MSI) is a genetic marker that is useful in the detection and treatment of Lynch syndrome (Sd). Although conventional techniques such as immunohistochemistry (IHC) and polymerase chain reaction (PCR) are the standards for MSI detection, the advent of next-generation sequencing (NGS) has offered new possibilities, especially with circulating DNA.

Case report

We present the case of a 26-year-old patient with Lynch Sd and a BRAF-mutated metastatic colon cancer. The discordant MSI results between the conventional methods and NGS posed challenges in making treatment decisions. Subsequent NGS analysis revealed a high MSI status, leading to participation in an immunotherapy trial, with remarkable clinical response.

Conclusion

This case emphasizes the importance of comprehensive molecular profiling and strong interdisciplinary collaborations, especially in cases with ambiguous MSI results.

NLRC5 promotes endometrial carcinoma progression by regulating NF-κB pathway-mediated mismatch repair gene deficiency

The innate immune molecule NLR family CARD domain-containing 5 (NLRC5) plays a significant role in endometrial carcinoma (EC) immunosurveillance. However, NLRC5 also plays a protumor role in EC cells. Mismatch repair gene deficiency (dMMR) can enable tumors to grow faster and also can exhibit high sensitivity to immune checkpoint inhibitors. In this study, we attempted to determine whether NLRC5-mediated protumor role in EC is via the regulation of dMMR. Our findings revealed that NLRC5 promoted the proliferation, migration, and invasion abilities of EC cells and induced the dMMR status of EC in vivo and in vitro. Furthermore, the mechanism underlying NLRC5 regulated dMMR was also verified. We first found NLRC5 could suppress nuclear factor-kappaB (NF-κB) pathway in EC cells. Then we validated that the positive effect of NLRC5 in dMMR was restricted when NF-κB was activated by lipopolysaccharides in NLRC5-overexpression EC cell lines. In conclusion, our present study confirmed the novel NLRC5/NF-κB/MMR regulatory mechanism of the protumor effect of NLRC5 on EC cells, thereby suggesting that the NLRC5-mediated protumor in EC was depend on the function of MMR.

Long-term efficacy and predictors of pembrolizumab-based regimens in patients with advanced esophageal cancer in the real world

BACKGROUND

Pembrolizumab combined with chemotherapy has been proven effective as first-line therapy in patients with advanced esophageal cancer. Few trials have assessed the safety and efficacy of this treatment in patients with locally advanced disease.

AIM

To analyze long-term outcomes of pembrolizumab in locally advanced or metastatic esophageal squamous cell carcinoma (ESCC) in the real world.

METHODS

Patients with advanced ESCC admitted to our center from October 2019 to October 2021 were enrolled in this study. Clinical staging of the patients was based on the 8th edition of the American Joint Committee on Cancer TNM staging system. The patients received different treatments based on clinical stage. In brief, patients with locally advanced and resectable ESCC received neoadjuvant therapy combined with surgery. For those who were not candidates for resection, radical concurrent chemoradiotherapy plus pembrolizumab was more preferable. Patients with metastatic ESCC or who were unsuitable for radiotherapy underwent chemotherapy in combination with pembrolizumab. Long-term survival outcomes such as overall survival (OS), progression-free survival, disease-free survival, long-term adverse effects (AEs), immune maintenance therapy and predictors of immune checkpoint inhibitors (ICIs) efficacy were evaluated.

RESULTS

A total of 55 patients with advanced ESCC were enrolled in this retrospective, observational study. The median age was 61 years (range 44-74), with 47.3% (26/55) of the patients in stage IV and 45.5% of the patients had the tumor (25/55) located in the middle third of the esophagus. The median OS in all patients was not reached. The 12-mo OS rate among all patients was 78.8% and the 18-mo OS rate was 72.7%. 9 patients died due to tumor progression and 7 patients died due to treatment-related complications. The therapeutic effect evaluated at the interim evaluation was significantly reflected in the long-term outcome. Patients with complete response or partial response in all patients (P = 0.005) and in the chemoradiotherapy plus pembrolizumab group (P = 0.007) obtained a better prognosis than non-responders. A total of 20 patients (20/55, 36%) received immune maintenance therapy. Baseline peripheral blood biomarkers of the neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, and neutrophil-to-(leukocyte-neutrophil) ratio did not predict the efficacy of ICIs.

CONCLUSION

Pembrolizumab combined with chemotherapy or radiotherapy resulted in favorable long-term survival in patients with locally advanced or metastatic ESCC, with safe and manageable long-term AEs.

Real-world dostarlimab use in advanced/recurrent endometrial cancer in France

INTRODUCTION

In October 2020, the French Health Authority granted early access outside of the clinical trial setting for dostarlimab, a programmed death-1 inhibitor. Dostarlimab was approved by the European Medicines Agency (in April 2021) as monotherapy for patients with post-platinum mismatch repair deficient/microsatellite instability-high advanced/recurrent endometrial cancer, based on the results of the GARNET trial (NCT02715284).

METHODS

This was a real-world descriptive analysis of patients granted cohort temporary authorization of use to receive dostarlimab between November 2020 and June 2021. Physicians could complete follow-up forms at each treatment cycle to provide clinical information, safety, and efficacy data. Safety and disease progression data were also captured through pharmacovigilance reports.

RESULTS

Of 95 temporary authorization of use requests made by 80 oncologists in 59 French hospitals, 87 patients were eligible, and 80 received≥1 dose of dostarlimab. Based on treatment response assessments received (n=43), the mean (standard deviation) time from treatment initiation to response evaluation was 11 (6) weeks. The disease control rate (complete plus partial responses plus stable disease rates) was 56% (n=24/43), and the overall response rate was 35% (n=15/43); both consistent with those reported in the GARNET trial. No new safety signals were reported.

DISCUSSION

The enrolment of 80 patients in an 8-month period highlights the need for access to novel treatment regimens in France for these patients post-platinum. Prospective randomized studies are ongoing to assess the efficacy and safety of dostarlimab and other checkpoint inhibitors as first-line treatment in patients with endometrial cancer.

The Role of Immunohistochemistry Markers in Endometrial Cancer with Mismatch Repair Deficiency: A Systematic Review

The objective of this systematic review was to summarize our current knowledge of the role of immunohistochemistry (IHC) markers for identifying mismatch repair-deficient (MMRd) tumors in endometrial cancer (EC). Identification of MMRd tumors, which occur in 13% to 30% of all ECs, has become critical for patients with colorectal and endometrial cancer for therapeutic management, clinical decision making, and prognosis. This review was conducted by two authors applying the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines using the following terms: “immunohistochemistry and microsatellite instability endometrial cancer” or “immunohistochemistry and mismatch repair endometrial cancer” or “immunohistochemistry and mismatch repair deficient endometrial cancer”. Among 596 retrieved studies, 161 fulfilled the inclusion criteria. Articles were classified and presented according to their interest for the diagnosis, prognosis, and theragnostics for patients with MMRd EC. We identified 10, 18, and 96 articles using IHC expression of two, three, or four proteins of the MMR system (MLH1, MSH2, MHS6, and PMS2), respectively. MLH1 promoter methylation was analyzed in 57 articles. Thirty-four articles classified MMRd tumors with IHC markers according to their prognosis in terms of recurrence-free survival (RFS), overall survival (OS), stage, grade, and lymph node invasion. Theragnostics were studied in eight articles underlying the important concentration of PD-L1 in MMRd EC. Even though the role of IHC has been challenged, it represents the most common, robust, and cheapest method for diagnosing MMRd tumors in EC and is a valuable tool for exploring novel biotherapies and treatment modalities.

Detection of Microsatellite Instability: State of the Art and Future Applications in Circulating Tumour DNA (ctDNA)

Simple Summary

Microsatellite instability (MSI) is a molecular fingerprint for defects in the mismatch repair system (dMMR) and is associated with higher risks of cancers. MSI/dMMR tumours are characterized by the accumulation of mutations throughout the genome, and particularly in microsatellite (MS) DNA repeat sequences. MSI stands as a major biomarker for familial cancer risk assessment, cancer prognosis, and therapeutic choices. Standard-of-care classification of MSI/dMMR tumours is most frequently achieved using immunohistochemistry or PCR-based assay directed against a set of five MS regions. However, novel molecular methods based on tumour tissue or plasma samples have been developed and could enter in the future trends of MSI testing. Here, we provide insights into these emerging approaches and discuss their advantages and limitations.

Abstract

Microsatellite instability (MSI) is a molecular scar resulting from a defective mismatch repair system (dMMR) and associated with various malignancies. MSI tumours are characterized by the accumulation of mutations throughout the genome and particularly clustered in highly repetitive microsatellite (MS) regions. MSI/dMMR status is routinely assessed in solid tumours for the initial screening of Lynch syndrome, the evaluation of cancer prognosis, and treatment decision-making. Currently, pentaplex PCR-based methods and MMR immunohistochemistry on tumour tissue samples are the standard diagnostic methods for MSI/dMMR. Other tissue methods such as next-generation sequencing or real-time PCR-based systems have emerged and represent viable alternatives to standard MSI testing in specific settings. The evolution of the standard molecular techniques has offered the opportunity to extend MSI determination to liquid biopsy based on the analysis of cell-free DNA (cfDNA) in plasma. This review aims at synthetizing the standard and emerging techniques used on tumour tissue samples for MSI/dMMR determination. We also provide insights into the MSI molecular techniques compatible with liquid biopsy and the potential clinical consequences for patients with solid cancers.

[Localized MSI/dMMR gastric cancer patients, perioperative immunotherapy instead of chemotherapy: The GERCOR NEONIPIGA phase II study is opened to recruitment]

INTRODUCTION

Perioperative chemotherapy is the standard strategy for localized gastric cancers. Nevertheless, this strategy seems to be inefficient, if not deleterious, for patients with tumors harboring microsatellite instability (MSI) and/or mismatch repair deficiency (dMMR), a tumor phenotype predictive for the efficacy of immune checkpoint inhibitors (ICKi).

AIM

The GERCOR NEONIPIGA single-arm phase II study (NCT04006262; EUDRACT 2018-004712-22) aims at evaluating the efficacy of a peri-operative strategy with nivolumab and ipilimumab in neoadjuvant setting, then nivolumab alone after surgery for patients with resectable MSI/dMMR gastric cancer.

MATERIAL AND METHODS

Main inclusion criteria are: gastric and oesogastric junction adenocarcinoma (GOA), T2-T4, all N stage and M0, MSI/dMMR. Patients will be treated with nivolumab 240mg Q2W, 6 infusions, and ipilimumab 1mg/kg Q6W, 2 infusions in neoadjuvant setting. Following surgery, patients with TRG 1-2-3 (Mandard tumor regression grade), acceptable tolerance of neoadjuvant treatment and postoperative ECOG performance status 0-1, will be treated with adjuvant nivolumab 480mg Q4W, 9 infusions.

RESULTS

The primary endpoint is pathological complete response rate (pCR-R). Based on a Fleming design, with α=5% and β=20%, 27 patients have to be evaluated (H0=5%; H1=20%). Secondary endpoints include disease-free survival, overall survival and safety.

CONCLUSION

This study is planned to include 32 patients to evaluate the pCR-R with the combination of nivolumab and ipilimumab in neoadjuvant setting for MSI/dMMR localized GOA. The MSI/MMR status should be systematically assessed on diagnostic biopsies of all GOA. If it meets its primary endpoint, the GERCOR NEONIPIGA study might mark a turning point in the management of localized MSI/dMMR GOA patients.