Tumor-Infiltrating Lymphocytes in Colorectal Cancer: The Fundamental Indication and Application on Immunotherapy

The clinical success of immunotherapy has revolutionized the treatment of cancer patients, bringing renewed attention to tumor-infiltrating lymphocytes (TILs) of various cancer types. Immune checkpoint blockade is effective in patients with mismatched repair defects and high microsatellite instability (dMMR-MSI-H) in metastatic colorectal cancer (CRC), leading the FDA to accelerate the approval of two programmed cell death 1 (PD-1) blocking antibodies, pembrolizumab and nivolumab, for treatment of dMMR-MSI-H cancers. In contrast, patients with proficient mismatch repair and low levels of microsatellite stability or microsatellite instability (pMMR-MSI-L/MSS) typically have low tumor-infiltrating lymphocytes and have shown unsatisfied responses to the immune checkpoint inhibitor. Different TILs environments reflect different responses to immunotherapy, highlighting the complexity of the underlying tumor-immune interaction. Profiling of TILs fundamental Indication would shed light on the mechanisms of cancer-immune evasion, thus providing opportunities for the development of novel therapeutic strategies. In this review, we summarize phenotypic diversities of TILs and their connections with prognosis in CRC and provide insights into the subsets-specific nature of TILs with different MSI status. We also discuss current clinical immunotherapy approaches based on TILs as well as promising directions for future expansion, and highlight existing clinical data supporting its use.

Brief family history questionnaire to screen for Lynch syndrome in women with newly diagnosed non-serous, non-mucinous ovarian cancers

ObjectivesWhile ovarian cancer is the third most common Lynch syndrome-associated cancer in women, there is no established screening strategy to identify Lynch syndrome in this population. The objective of this study was to assess whether the 4-item brief Family History Questionnaire can be used as a screening tool to identify women with ovarian cancer at risk of Lynch syndrome.MethodsIn this prospective cohort study, participants with newly diagnosed non-serous, non-mucinous ovarian cancer completed the brief Family History Questionnaire, extended Family History Questionnaire, and had tumors assessed with immunohistochemistry for mismatch repair proteins, MLH1 methylation, and microsatellite instability testing. All underwent universal germline testing for Lynch syndrome. Performance characteristics were compared between the brief Family History Questionnaire, extended Family History Questionnaire, immunohistochemistry±MLH1 methylation, and microsatellite instability testing.ResultsOf 215 participants, 169 (79%) were evaluable with both the brief Family History Questionnaire and germline mutation status; 12 of these 169 were confirmed to have Lynch syndrome (7%). 10 of 12 patients (83%) with Lynch syndrome were correctly identified by the brief Family History Questionnaire, compared with 6 of 11 (55%) by the extended Family History Questionnaire, 11 of 13 (85%) by immunohistochemistry±MLH1 methylation, and 9 of 11 (82%) by microsatellite instability testing. The sensitivity, specificity, positive predictive values, and negative predictive values of the brief Family History Questionnaire were 83%, 65%, 15%, and 98%, respectively. A combined approach with immunohistochemistry and the brief Family History Questionnaire correctly identified all 12 patients with Lynch syndrome. The brief Family History Questionnaire was more sensitive than the extended Family History Questionnaire and took <10 min for each patient to complete.ConclusionsThe brief Family History Questionnaire alone or combined with immunohistochemistry may serve as an adequate screening strategy, especially in centers without access to universal tumor testing.

ABCC9 Is Downregulated and Prone to Microsatellite Instability on ABCC9tetra in Canine Breast Cancer

Tumorigenesis is associated with metabolic abnormalities and genomic instability. Microsatellite mutations, including microsatellite instability (MSI) and loss of heterozygosity (LOH), are associated with the functional impairment of some tumor-related genes. To investigate the role of MSI and LOH in sporadic breast tumors in canines, 22 tumors DNA samples and their adjacent normal tissues were evaluated using polyacrylamide gel electrophoresis and silver staining for 58 microsatellites. Quantitative real-time polymerase chain reaction, promoter methylation analysis and immunohistochemical staining were used to quantify gene expression. The results revealed that a total of 14 tumors (6 benign tumors and 8 breast cancers) exhibited instability as MSI-Low tumors. Most of the microsatellite loci possessed a single occurrence of mutations. The maximum number of MSI mutations on loci was observed in tumors with a lower degree of differentiation. Among the unstable markers, FH2060 (4/22), ABCC9tetra (4/22) and SCN11A (6/22) were high-frequency mutation sites, whereas FH2060 was a high-frequency LOH site (4/22). The ABCC9tetra locus was mutated only in cancerous tissue, although it was excluded by transcription. The corresponding genes and proteins were significantly downregulated in malignant tissues, particularly in tumors with MSI. Furthermore, the promoter methylation results of the adenosine triphosphate binding cassette subfamily C member 9 (ABCC9) showed that there was a high level of methylation in breast tissues, but only one case showed a significant elevation compared with the control. In conclusion, MSI-Low or MSI-Stable is characteristic of most sporadic mammary tumors. Genes associated with tumorigenesis are more likely to develop MSI. ABCC9 protein and transcription abnormalities may be associated with ABCC9tetra instability.

HSP110 as a Diagnostic but Not a Prognostic Biomarker in Colorectal Cancer With Microsatellite Instability

Determination of microsatellite instability (MSI) using molecular test and deficient mismatch repair (dMMR) using immunohistochemistry (IHC) has major implications on colorectal cancer (CRC) management. The HSP110 T17 microsatellite has been reported to be more monomorphic than the common markers used for MSI determination. Large deletion of HSP110 T17 has been associated with efficacy of adjuvant chemotherapy in dMMR/MSI CRCs. The aim of this study was to evaluate the interest of HSP110 deletion/expression as a diagnostic tool of dMMR/MSI CRCs and a predictive tool of adjuvant chemotherapy efficacy. All patients with MSI CRC classified by molecular testing were included in this multicenter prospective cohort (n = 381). IHC of the 4 MMR proteins was carried out. HSP110 expression was carried out by IHC (n = 343), and the size of HSP110 T17 deletion was determined by PCR (n = 327). In the 293 MSI CRCs with both tests, a strong correlation was found between the expression of HSP110 protein and the size of HSP110 T17 deletion. Only 5.8% of MSI CRCs had no HSP110 T17 deletion (n = 19/327). HSP110 T17 deletion helped to re-classify 4 of the 9 pMMR/MSI discordance cases as pMMR/MSS cases. We did not observe any correlation between HSP110 expression or HSP110 T17 deletion size with time to recurrence in patients with stage II and III CRC, treated with or without adjuvant chemotherapy. HSP110 is neither a robust prognosis marker nor a predictor tool of adjuvant chemotherapy efficacy in dMMR/MSI CRC. However, HSP110 T17 is an interesting marker, which may be combined with the other pentaplex markers to identify discordant cases between MMR IHC and MSI.

Microsatellite Instability, Epstein–Barr Virus, and Programmed Cell Death Ligand 1 as Predictive Markers for Immunotherapy in Gastric Cancer

Immunotherapy benefits selected cases of gastric cancer (GC), but the correlation between biomarkers and prognosis is still unclear. Fifty-two patients with GC who underwent immunotherapy were enrolled from June 2016 to December 2020. Their clinical features and biomarkers—microsatellite instability-high (MSI-H), programmed cell death ligand 1 (PD-L1) combined positive score (CPS), and Epstein–Barr encoding region (EBER)—were analyzed. Eight patients had MSI-H, five patients had EBER, 29 patients had CPS ≥ 1, and 20 patients had no biomarker. The overall response rates (ORRs) of the MSI-H, EBER, PD-L1 CPS ≥ 1, and all-negative group were 75%, 60%, 44.8%, and 15%, respectively. Compared with that of the all-negative group, progression-free survival (PFS) was better in the MSI-H (p = 0.018), CPS ≥ 5 (p = 0.012), and CPS ≥ 10 (p = 0.006) groups, but not in the EBER (p = 0.2) and CPS ≥ 1 groups (p = 0.35). Ten patients had combined biomarkers, CPS ≥ 1 with either MSI-H or EBER. The ORRs were 66.7% for CPS ≥ 1 and MSI-H and 75% for CPS ≥ 1 and EBER. PFS was better in patients with combined biomarkers (p = 0.01). MSI-H, EBER, and CPS are useful biomarkers for predicting the efficacy of immunotherapy.

Association Between Microsatellite Instability and 18F-FDG PET/CT Data in Colorectal Cancer Patients

Aim: Our aim in this study was to evaluate the relationship between microsatellite instability (MSI) status and 18F-FDG PET/CT data in patients with colorectal cancer.Materials and Methods: Our study included 74 patients who underwent PET/CT in preoperative staging with the diagnosis of colorectal cancer and then underwent surgical resection. In the immunohistochemical examination, nuclear staining was considered positive for all antibodies. Normal colon mucosa and lymphocytes in tissue were used as an internal positive control group. The absence of nuclear staining in tumor cells was considered "loss" in "Mismatch Repair Gen" proteins. MSI status of patients was divided into 3 groups according to the occurrence of MLH1, PMS2, MSH2, MSH6 gene proteins, and also the number of MSI genes. It is defined as a high frequency of microsatellite instability (MSI-H) when two or more of the five markers in the tumor DNA were positive. If only one marker was positive, the tumor is termed as low frequency of MSI (MSI-L). And MSS is determined when all of the five markers were negative. Results: While MSI was not detected in 56 of the patients (75.7%), MSI was detected in 18 patients (24.3%). 4 patients (5.4%) had MSH-L, while 14 patients (18.9%) had MSH-H. In the analysis made considering all 3 groups, there was no statistically significant relationship between MSI status and SUVmax (p=0.835). Liver metastases were present in 11 (36.7%) of 30 patients who were metastatic at the time of diagnosis. Distant metastasis incidence was lower in 18F-FDG PET/CT in patients with MSI-H (p=0.010). In addition, a significant correlation was found between the presence of liver metastases and MSI, and liver metastasis was not observed in any of the 14 patients with MSI-H (p=0.041).Conclusion: Although not statistically significant, SUVmax values were found to be higher in patients with MSI-H. In addition, metastasis rates were found to be lower in patients with microsatellite instability in accordance with the literature data.

Microsatellite Instability as a Maker of Prognosis: a Systematic Review and Meta-analysis of Endometrioid Endometrial Cancer Survival Data

Introduction To investigate whether microsatellite instability (MSI) is an important prognostic biomarker for endometrioid endometrial cancer (EEC).Methods The PubMed, EMBASE and the Cochrane Cooperative Library databases were searched from inception to July 2021. Overall survival, disease-free survival, progression-free survival, EEC-specific survival, recurrence-free survival and the recurrence rate were pooled to analyze the correlation between MSI and EEC. In addition, Egger’s regression analysis and Begg’s test were used to detect publication bias.Results 17 studies met the inclusion criteria and were included in our meta-analysis with a sample size of 4723, and the included patients with endometrioid cancer (EC) all were EEC. The pooled hazard ratios (HR) in patients with EEC shown that MSI was significantly associated with shorter overall survival [HR=1.37, 95% confidence interval (CI) (1.00-1.86), p=0.048, I2=60.6%], shorter disease-free survival [HR=1.99, 95% CI (1.31-3.01), p=0.000, I2=67.2%], shorter EEC-specific survival [HR=2.07, 95% CI (1.35-3.18), p=0.001, I2=31.6%] and a higher recurrence rate [Odds ratios (OR)=2.72, 95% CI (1.56-4.76), p=0.000, I2=0.0%]. In the early-stage EEC subgroup, MSI was significantly associated with shorter overall survival [HR=1.47, 95% CI (1.11-1.95), p=0.07], shorter disease-free survival [HR=4.17, 95% CI (2.37-7.41), p=0.000], and shorter progression-free survival [HR=2.41, 95% CI (1.05-5.54), p=0.039]. No significant heterogeneity was observed in overall survival (I2=20.9%), disease-free survival (I2=0.0%), or progression-free survival (I2=0.0%) in patients with early-stage EEC. Meanwhile, publication bias was not observed, and the p-value for Egger’s test of overall survival, disease-free survival, and EEC-specific survival were p=0.131, p=0.068 and p=0.987, respectively.Conclusion MSI is likely an important biomarker for poor prognosis in patients with EEC, and this correlation is even more certain in patients with early-stage EEC.