The ATOM-Seq sequence capture panel can accurately predict microsatellite instability status in formalin-fixed tumour samples, alongside routine gene mutation testing.

Microsatellite instability (MSI) occurs across a number of cancers and is associated with different clinical characteristics when compared to microsatellite stable (MSS) cancers. As MSI cancers have different characteristics, routine MSI testing is now recommended for a number of cancer types including colorectal cancer (CRC). Using gene panels for sequencing of known cancer mutations is routinely performed to guide treatment decisions. By adding a number of MSI regions to a small gene panel, the efficacy of simultaneous MSI detection in a series of CRCs was tested. Tumour DNA from formalin-fixed, paraffin-embedded (FFPE) tumours was sequenced using a 23-gene panel kit (ATOM-Seq) provided by GeneFirst. The mismatch repair (MMR) status was obtained for each patient from their routine pathology reports, and compared to MSI predictions from the sequencing data. By testing 29 microsatellite regions in 335 samples the MSI status was correctly classified in 314/319 samples (98.4% concordance), with sixteen failures. By reducing the number of regions in silico, comparable performance could be reached with as few as eight MSI marker positions. This test represents a quick, and accurate means of determining MSI status in FFPE CRC samples, as part of a routine gene mutation assay, and can easily be incorporated into a research or diagnostic setting. This could replace separate mutation and MSI tests with no loss of accuracy, thus improving testing efficiency.

The diagnostic value of histogram analysis of DWI and DKI for the mismatch repair status of rectal adenocarcinoma.

Objectives: To compare the diagnostic value of histogram analysis derived from diffusion weighted imaging (DWI) and diffusion kurtosis imaging (DKI) in differentiating the mismatch repair (MMR) status of rectal adenocarcinoma. Methods: DWI and DKI were performed in 124 patients with rectal adenocarcinoma, which were divided into deficient mismatch repair (dMMR) group and proficient mismatch repair (pMMR) group. The patients' general clinical information, pathology and image characteristics were compared. The histogram analysis of apparent diffusion coefficient (ADC), diffusion kurtosis (K) and diffusion coefficient (D)derived from DWI and DKI at b values of 1000 and 2000 s/mm2 were calculated. The diagnostic efficacy of quantitative parameters for MMR in rectal adenocarcinoma was compared. Results: The mean, 50th, 75th and 90th in ADC quantitative parameters of dMMR group were lower when the b value was 2000 s/mm2 (all P < 0.05). With b value of 1000 s/mm2, the 10th, 25th, and 50th in the dMMR group were lower, and the skewness was higher (all P < 0.05). D values (10th, 25th and 50th) derived from DKI quantitative parameters were lower in the dMMR group. The K values (75th, 90th and Kskewness) were higher in the dMMR group, while Kkurtosis was lower (all P < 0.05). The results of multivariate logistic regression analysis showed that ADC75th(b = 2000 s/mm2), ADCskewness (b = 1000 s/mm2) and Kskewness were the statistical significant parameters (P = 0.014, 0.036 and 0.002, respectively), and the AUC values were 0.713, 0.818 and 0.835, respectively. Conclusion: Histogram analysis derived from DWI and DKI can be good predictor of MMR. Kskewness is the strongest independent factor for predicting MMR.

Diabetes mellitus complications associated with recurrence of stage I endometrioid endometrial cancer: A single-center retrospective study.

OBJECTIVE: Identifying clinical features that are associated with recurrence of endometrioid endometrial carcinoma (EEC) in patients with diabetes mellitus (DM). METHODS: A single-center retrospective cohort study was performed on patients with a diagnosis of both DM and Stage I EEC. Clinical and pathologic features were analyzed in relation to 5-year progression free survival (PFS). Kaplan-Meier Curves and Cox proportional hazard ratios were utilized to assess effect on 5-year PFS. RESULTS: A total of 539 patients were included, with biopsy proven recurrence in 86 (18 %), and 456 (82 %) with no evidence of recurrence. Age, BMI, HgbA1c, metformin use, number of antihyperglycemic medications, use of adjuvant radiation, and surgical approach were not associated with differences in PFS. Presence of end-organ complications associated with diabetes was correlated with worse PFS (HR 1.78, 95 % CI 1.1-2.9, P = 0.02), and specifically diabetic neuropathy was associated with higher rates of recurrence (HR 3.6, 95 % CI 2.1-6.2, P < 0.01). In this cohort, PFS was independently associated with extent of myoinvasion (HR 2.33, 95 % CI 1.4-3.7, P < 0.01) as well as both microsatellite instability (HR 3.43, 95 % CI 1.8-6.6, P < 0.01), and no specific molecular profile (HR 0.3, 95 % CI 0.2-0.6, P < 0.01) molecular subtypes. CONCLUSIONS: In patients with DM and EEC, extent of myoinvasion and TCGA molecular subtype correlated with worse PFS. Control of DM as evidenced by HgbA1c, BMI, and use of antihyperglycemic medications did not correlate with PFS in our cohort of patients with Stage I EEC, while the presence of diabetic neuropathy was associated with a higher risk of recurrence. These results highlight importance of evaluating diabetes severity and molecular subtype in endometrial cancer patients.

Single-cell AI-based detection and prognostic and predictive value of DNA mismatch repair deficiency in colorectal cancer.

Testing for DNA mismatch repair deficiency (MMRd) is recommended for all colorectal cancers (CRCs). Automating this would enable precision medicine, particularly if providing information on etiology not captured by deep learning (DL) methods. We present AIMMeR, an AI-based method for determination of mismatch repair (MMR) protein expression at a single-cell level in routine pathology samples. AIMMeR shows an area under the receiver-operator curve (AUROC) of 0.98, and specificity of ≥75% at 98% sensitivity against pathologist ground truth in stage II/III in two trial cohorts, with positive predictive value of ≥98% for the commonest pattern of somatic MMRd. Lower agreement with microsatellite instability (MSI) testing (AUROC 0.86) reflects discordance between MMR and MSI PCR rather than AIMMeR misclassification. Analysis of the SCOT trial confirms MMRd prognostic value in oxaliplatin-treated patients; while MMRd does not predict differential benefit of chemotherapy duration, it correlates with difference in relapse by regimen (PInteraction = 0.04). AIMMeR may help reduce pathologist workload and streamline diagnostics in CRC.

Amphicrine carcinoma of the right colon, a report of a case and review of literature.

Mixed neuroendocrine and non-neuroendocrine neoplasms, recently recognized in the WHO classification as (MiNEN), are rare tumors of the gastrointestinal tract. These tumors are composed of two distinct cellular components; a well- or poorly differentiated neuroendocrine tumor and a non-neuroendocrine tumor, usually in the form of an adenocarcinoma, either admixed with or adjacent to one another. A rarer phenotype is a tumor in which the endocrine and epithelial cell features occur within the same cell; i.e. amphicrine carcinoma. Herein, we report the case of an 80-year-old female patient who presented with melena, and who, on biopsy was diagnosed as amphicrine carcinoma that was mismatch repair deficient (MMRd) with loss of MLH1/PMS2 nuclear expression by immunohistochemistry. The histological and immunohistochemical findings of this rare entity are presented with review of pertinent literature.

Glioma oncogenesis in the Constitutional mismatch repair deficiency (CMMRD) syndrome.

Background: Constitutional mismatch repair deficiency (CMMRD) is a cancer predisposition due to biallelic mutations in one of the mismatch repair (MMR) genes associated with early onset of cancers, especially high-grade gliomas. Our aim was to decipher the molecular specificities of these gliomas. Methods: Clinical, histopathological, and whole exome sequencing data were analyzed in 12 children with genetically proven CMMRD and a high-grade glioma. Results: PDL1 expression was present in immunohistochemistry in 50% of the samples. In 9 patients, the glioma harbored an ultra-hypermutated phenotype (104-635 coding single nucleotide variants (SNV) per Mb, median 204). Driver mutations in POLE and POLD1 exonuclease domains were described for 8 and 1 patients respectively and were always present in the mutation burst with the highest variant allele frequency (VAF). The mutational signatures were dominated by MMR-related ones and similar in the different mutation bursts of a same patient without subsequent enrichment of the mutation signatures with POL-driven ones. Median number of coding SNV with VAF above one of the driving polymerase mutation per Mb was 57 (17-191). Our findings suggest that somatic polymerase alterations does not entirely explain the ultra-hypermutant phenotype. SETD2, TP53, NF1, EPHB2, PRKDC, and DICER1 genes were frequently mutated with higher VAF than the deleterious somatic polymerase mutation. Conclusions: CMMRD-associated gliomas have a specific oncogenesis that does not involve usual pathways and mutations seen in sporadic pediatric or adult glioblastomas. Frequent alterations in other pathways such as MAPK may suggest the use of other targeted therapies along with PD1 inhibitors.

Real-world outcomes of stage II and III colorectal cancers treated by postoperative adjuvant chemotherapy based on the mismatch repair status.

PURPOSE: In Japan, immunohistochemistry for mismatch repair (MMR) proteins targeted at stage II and III colorectal cancers (CRCs) has been covered by national insurance since October, 2022. This study aimed to clarify the long-term outcomes of patients with stage II and III CRCs receiving postoperative adjuvant chemotherapy based on their MMR status. METHODS: The outcomes of 640 patients who underwent radical surgery for stage II and III CRCs were analyzed retrospectively. RESULTS: Deficient MMR (dMMR) was diagnosed in 41 (13.3%) patients with stage II and 28 (9.1%) patients with stage III CRC. The overall survival and recurrence rates were not significantly different between the patients with stage II and those with stage III CRC. The risk factors for recurrence among those with stage II CRC were tumors on the left side, T4 disease, and the presence of BRAF wild type. The recurrence rates were lower in the stage II CRC patients with sporadic dMMR than in those with suspected Lynch syndrome (LS). The first site of recurrence was more frequently the peritoneum or distant lymph node in patients with dMMR. CONCLUSIONS: Stage II CRC patients with sporadic dMMR were found to have a very good prognosis. On the other hand, peritoneal dissemination or distant lymph node metastasis tended to develop in patients with dMMR.

Clinical Insights and Potential Benefits of Stem Cell Transplantation for Constitutional Mismatch Repair Deficiency: A Case Report of Two Siblings.

Constitutional mismatch repair deficiency (CMMRD) syndrome, caused by biallelic mutations in mismatch repair genes, is one of the most aggressive hereditary cancer syndromes. This report presents the clinical course of two brothers diagnosed with CMMRD. The first patient was diagnosed with T-cell lymphoma at the age of three and a half years, a relapse, and synchronous glioblastoma at the age of seven and a half years. After treatment with chemotherapy and neurosurgery, haematopoietic stem cell transplant (HSCT) was performed. The second patient was diagnosed with mediastinal T-cell lymphoma at the age of two and a half years and a relapse at the age of four and a half years. He also received chemotherapy and underwent HSCT. Both patients exhibited café au lait macules (CALMs), a common but non-specific feature of CMMRD, often confused with neurofibromatosis type 1 (NF1) syndrome. This study highlights the phenotype of CMMRD syndrome, associated cancers, and the potential benefits of stem cell transplantation. Previous reports suggest that allogeneic HSCT might reduce subsequent haematological malignancies and increase survival.

Durable response to pembrolizumab in hepatic metastasis from colonic carcinoma with Lynch syndrome: a case report.

Pembrolizumab and other immunotherapies have become central in treating metastatic colon cancer, particularly effective in patients with mismatch repair deficiencies. We report a case involving a man who initially underwent radical surgery for sigmoid colon cancer on April 27, 2011, followed by hepatic tumor resection on September 21, 2017. Post-surgery, he received eight cycles of adjuvant chemotherapy with the CAPEOX regimen and was regularly monitored through CT and MRI scans. On August 24, 2022, liver metastases were detected, and he was diagnosed with Lynch syndrome (LS) due to germline mutation in the MSH2 and EPCAM genes. He commenced treatment with 200mg of pembrolizumab intravenously every three weeks on September 2, 2022, and demonstrated a sustained response. However, after 17 cycles, he developed a treatment related adverse event (TRAE) of pancreatic endocrine dysfunction, leading to type 1 diabetes, managed with subcutaneous insulin injections. After 30 cycles of treatment, no evidence of disease was observed. This case underscores the significant clinical benefits of first-line pembrolizumab in managing hepatic metastasis in colonic carcinoma associated with LS, despite the occurrence of TRAEs. It raises critical questions regarding the optimal duration of immunotherapy following a complete or partial response and whether treatment should be discontinued upon the emergency of TRAEs. Continued research and forthcoming clinical trials with checkpoint inhibitors are expected to refine treatment protocols for LS-associated carcinoma.

High levels of tumor cell-intrinsic STING signaling are associated with increased infiltration of CD8+ T cells in dMMR/MSI-H gastric cancer.

Mismatch repair deficient (dMMR)/microsatellite instability-high (MSI-H) gastric cancer (GC) exhibits an immune-active tumor microenvironment (TME) compared to MMR proficient (pMMR)/microsatellite stable/Epstein-Barr virus-negative [EBV (-)] GC. The tumor cell-intrinsic cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway has been considered a key regulator of immune cell activation in the TME. However, its significance in regulating the immune-active TME in dMMR/MSI-H GC remains unclear. Here, we demonstrated that tumor cell-intrinsic cGAS-STING was highly expressed in dMMR GC compared to pMMR/EBV (-) GC. The expression of tumor cell-intrinsic STING was significantly and positively associated with the number of CD8+ tumor-infiltrating lymphocytes in GC. Analysis of TCGA datasets revealed that the expression of interferon-stimulated genes and STING downstream T-cell attracting chemokines was significantly higher in MSI-H GC compared to other subtypes of GC with EBV (-). These results suggest that tumor cell-intrinsic STING signaling plays a key role in activating immune cells in the dMMR/MSI-H GC TME and might serve as a novel biomarker predicting the efficacy of immunotherapy for GC treatment.

Integrated molecular profiling of RAS, BRAF mutations, and mismatch repair status in advanced colorectal carcinoma: insights from gender and tumor laterality.

Background: Colorectal carcinoma (CRC) is one of the most frequently diagnosed forms of cancer worldwide. The RAS (KRAS, NRAS) and BRAF genes encode proteins that are important therapeutic targets for the treatment of CRC and, together with the mismatch repair (MMR) system, are closely related to patient prognosis and survival in advanced CRC. Here we evaluate the mutational profile and the frequency of mutations in the KRAS, NRAS and BRAF genes, along with the expression of MMR in advanced CRC, at a tertiary hospital in southern Brazil. Methods: A cross-sectional retrospective study was carried out, where molecular analysis of mutations in the KRAS, NRAS and BRAF genes was carried out, as well as immunohistochemistry for MMR proteins. Results: Next-generation sequencing (NGS) analysis of 310 tumors revealed that 202 patients (65.2%) had mutations. The KRAS gene (53.2%) was the most frequently mutated in our sample, with G12D being the most frequent, representing 30.5% of the mutations in this gene. The most frequent mutation found in BRAF was V600E (n=25; 89.3%) and differed significantly in women and in the right colon in patients with MMR deficiency. Among the 283 patients tested for MMR, the rate of loss of expression was 8.8% (25/283). Conclusions: Deficiency in the MMR system is associated with the presence of the BRAF V600E mutation, tumors located in the right colon, and the female sex. In our case series, more than 60% of patients had at least one mutation in KRAS, NRAS, or BRAF. The presence of mutations in these genes is closely related to CRC prognosis and helps define the best therapeutic approach in patients with metastatic CRC.

PD-1 blockade combined with chemotherapy and bevacizumab in DNA mismatch repair-proficient/microsatellite stable colorectal liver metastases.

Background: Single-agent immunotherapy is less effective in patients with DNA mismatch repair-proficient/microsatellite stable (pMMR/MSS) metastatic colorectal cancer (mCRC). Whether pMMR/MSS mCRC patients benefit from combination immunotherapy remains unclear. This study aimed to evaluate the efficacy and safety of anti-programmed cell death protein 1 (PD-1) therapy combined with chemotherapy and bevacizumab in pMMR/MSS colorectal liver metastases (CRLM) patients. Methods: A total of 12 patients with pMMR/MSS CRLM treated at The Sixth Affiliated Hospital of Sun Yat-sen University were enrolled. All patients were treated with at least 4 doses of PD-1 monoclonal antibody combined with chemotherapy and bevacizumab as neoadjuvant/adjuvant therapy. Results: A total of 10 of the 12 patients received the combined therapies before primary tumor resection; the disease control rate (DCR) was 100% (10/10), and the objective response rate (ORR) was 70% (7/10). The ORR of liver metastases was 75% (9/12). Pathological complete response (pCR) was achieved in 1 primary tumor patient and 2 patients with hepatic lesions. A total of 5 patients underwent simultaneous resection of the primary tumor and liver metastases; 9 patients underwent microwave ablation for liver metastases. A total of 7 patients were assessed as having no evidence of disease (NED) with a median progression-free survival (PFS) interval of 9.2 (1.5-15.8) months after multimodality treatments for both primary and metastatic lesions. No severe immune-related adverse events (irAEs) and operational complications were observed. Conclusions: PD-1 blockade combined with chemotherapy and bevacizumab might be safe and effective for patients with pMMR/MSS CRLM. This treatment strategy might lead to better tumor regression and a higher chance of achieving NED.

Expression of Programmed Death Ligand 1 [PD-L1] and Mismatch Repair Status in Squamous Cell Carcinomas of Cervix.

Background and Objectives: To assess mismatch repair (MMR) status and programmed death-ligand 1 (PD-L1) expression in squamous cell carcinomas of the cervix and their association with clinicopathologic parameters. Material and Methods: Expression of PD-L1 and MMR status (MSH2, MSH6, MLH1, and PMS2) was assessed on 50 cases of SCCs of the cervix by immunohistochemistry. Results: 80% of tumor cells and 84% of tumor-infiltrating lymphocytes showed PD-L1 expression. 80% of cases had a combined positive score (CPS) of > 1, whereas 20% had a CPS of < 1. 94% of cases showed pMMR proteins, while 6% showed dMMR. 94% of the SCCs were HPV associated, and 6% were HPV-independent. All HPV-independent SCCs of the cervix showed PD-L1 expression, and all HPV-associated SCCs showed MMR deficiency. Between PD-L1 expression in the tumor and the grade of the tumor, a statistically significant association was noted (p = 0.022). All MMR-deficient SCCs were HPV-independent. Conclusion: This research highlighted the HPV association in cervical SCCs in the Indian population. Most of the cervical SCCs were HPV-associated. Furthermore, most of the HPV-associated SCCs were MMR stable. This study found no significant association between MMR status and PD-L1 expression in cervical SCCs.

ENGOT-en11/GOG-3053/KEYNOTE-B21: A Randomised, Double-Blind, Phase 3 Study of Pembrolizumab or Placebo Plus Adjuvant Chemotherapy With or Without Radiotherapy in Patients With Newly Diagnosed, High-Risk Endometrial Cancer.

BACKGROUND: Pembrolizumab plus chemotherapy provides clinically meaningful benefit as first-line therapy for advanced (locoregional extension and residual disease after surgery)/metastatic/recurrent pMMR and dMMR endometrial cancer (EC), with greater magnitude of benefit in the dMMR phenotype. We evaluated addition of pembrolizumab to adjuvant chemotherapy (with/without radiation therapy) among patients with newly-diagnosed, high-risk EC without any residual macroscopic disease following curative-intent surgery. METHODS: Patients with histologically confirmed high-risk (FIGO stage I/II of non-endometrioid histology or endometrioid histology with p53/TP53 abnormality, or stage III/IVA of any histology) EC following surgery with curative intent and no evidence of disease postoperatively, with no prior radiotherapy or systemic therapy. Patients were randomised to pembrolizumab 200mg or placebo Q3W for 6 cycles added to carboplatin-paclitaxel followed by pembrolizumab 400mg or placebo Q6W for 6 cycles per treatment assignment. Radiotherapy was at the investigator's discretion. Primary endpoints were investigator-assessed disease-free survival (DFS) and overall survival in the intention-to-treat population. RESULTS: 1095 patients were randomised (pembrolizumab, n=545; placebo, n=550). At this interim analysis (data cutoff, 4-March2024), 119 (22%) DFS events occurred in the pembrolizumab group and 121 (22%) occurred in the placebo group (hazard ratio, 1.02 [95% CI, 0.79‒1.32]; P=0.570). Kaplan-Meier estimates of 2-year DFS rates were 75% and 76% in the pembrolizumab and placebo groups, respectively. The hazard ratio for DFS was 0.31 (95% CI, 0.14‒0.69) in the dMMR population (n=281) and 1.20 (95% CI, 0.91‒1.57) in the pMMR population (n=814). Grade ≥3 adverse events (AEs) occurred in 386 of 543 (71%) and 348 of 549 (63%) patients in the pembrolizumab and placebo groups, respectively. No treatment-related grade 5 AEs occurred. CONCLUSION: Adjuvant pembrolizumab plus chemotherapy did not improve DFS in patients with newly-diagnosed, high-risk, all-comer EC. Preplanned subgroup analyses for stratification factors suggests pembrolizumab plus chemotherapy improved DFS in patients with dMMR tumours. Safety was manageable.

Serotonin's Role in Inflammatory Signaling Pathway Modulation for Colon Cancer Suppression.

Background Neurons can be effectively regulated by serotonin and dopamine. Their role in anti-inflammatory pathways opens new doors for therapeutic research, particularly in chemotherapeutics. The present study investigated serotonin's role in suppressing inflammation and its potential anticancer effects in KERATIN-forming tumor cell line HeLa cells (KB cells).  Methods - in vitro and in silico analysis The study delved further into the molecular mechanisms by assessing the expression levels of key markers involved in inflammation and cancer progression, such as B-cell leukemia/lymphoma 2 protein (BCl-2), tumor necrosis factor-alpha (TNF-α) and Interleukin-6 (IL-6) using Real-time reverse-transcriptase-polymerase chain reaction at concentrations below the IC50 (50 and 100 µg/ml). The binding capability of serotonin (CID 5202) with glycoform of human interleukin 6 (PDB: 7NXZ) was analyzed with the help of Schrodinger molecular suites. Results The findings showcased serotonin's potent growth inhibition in KB cells, with an IC50 value of 225±3.1µg/ml. Additionally, it demonstrated a multifaceted impact by downregulating the expression of BCl-2, TNF-α, and IL-6, pivotal factors in cancer cell survival and inflammation regulation. The docking score was - 5.65 (kcal/mol) between serotonin and glycoform of Human Interleukin 6. It is bound with ASN 143 by two hydrogen bonds. Thus, molecular docking analysis showed an efficient bounding pattern. The research findings indicate that serotonin successfully blocks NF-κB pathways in KB cells, underscoring its therapeutic promise against colon cancer and offering vital information for additional clinical investigation.  Conclusion According to the study's conclusion, serotonin has a remarkable anticancer potential by effectively blocking NF-κB B pathways in KB cells, revealing its promising potential as a therapeutic agent against colon cancer. These comprehensive findings offer significant insights into serotonin's intricate molecular interactions and its profound impact on cancer-related signaling pathways, paving the way for further exploration and potential clinical applications in cancer treatment strategies.

Immune microenvironmental heterogeneity according to tumor DNA methylation phenotypes in microsatellite instability-high colorectal cancers.

The detailed association between tumor DNA methylation, including CpG island methylation, and tumor immunity is poorly understood. CpG island methylator phenotype (CIMP) is observed typically in sporadic colorectal cancers (CRCs) with microsatellite instability-high (MSI-H). Here, we investigated the differential features of the tumor immune microenvironment according to CIMP status in MSI-H CRCs. CIMP-high (CIMP-H) or CIMP-low/negative (CIMP-L/0) status was determined using MethyLight assay in 133 MSI-H CRCs. All MSI-H CRCs were subjected to digital pathology-based quantification of CD3 + /CD8 + /CD4 + /FoxP3 + /CD68 + /CD204 + /CD177 + tumor-infiltrating immune cells using whole-slide immunohistochemistry. Programmed death-ligand 1 (PD-L1) immunohistochemistry was evaluated using the tumor proportion score (TPS) and combined positive score (CPS). Representative cases were analyzed using whole-exome and RNA-sequencing. In 133 MSI-H CRCs, significantly higher densities of CD8 + tumor-infiltrating lymphocytes (TILs) were observed in CIMP-H tumors compared with CIMP-L/0 tumors. PD-L1 TPS and CPS in CIMP-H tumors were higher than in CIMP-L/0 tumors. Next-generation sequencing revealed that, compared with CIMP-L/0 tumors, CIMP-H tumors had higher fractions of CD8 + T cells/cytotoxic lymphocytes, higher cytolytic activity scores, and activated immune-mediated cell killing pathways. In contrast to CIMP-L/0 tumors, most CIMP-H tumors were identified as consensus molecular subtype 1, an immunogenic transcriptomic subtype of CRC. However, there were no differences in tumor mutational burden (TMB) between CIMP-H and CIMP-L/0 tumors in MSI-H CRCs. In conclusion, CIMP-H is associated with abundant cytotoxic CD8 + TILs and PD-L1 overexpression independent of TMB in MSI-H CRCs, suggesting that CIMP-H tumors represent a typical immune-hot subtype and are optimal candidates for immunotherapy in MSI-H tumors.

Utility of pembrolizumab for metastatic castrate resistant prostate cancer with MMR deficiency.

Molecular tumor profiling has become an important diagnostic for prostate cancer, allowing for personalized treatment regimens based on somatic and germline genetic information. We report a 67-year-old patient with metastatic castrate-resistant prostate cancer which was intermittently responsive to androgen-deprivation therapy, docetaxel, abiraterone, radium-223, Sipuleucel-T, and radiotherapy who ultimately demonstrated a remarkable and durable response to pembrolizumab. Our case report underlines the significance of early tumor molecular profiling in aggressive or atypical prostate cancer patients and exhibits the potential for a remarkable clinical response with immunotherapy in candidates with the appropriate tumor profiles.

Fusobacterium Nucleatum Promotes Microsatellite Instability in Colorectal Carcinoma Through Up-regulation of miRNA-155-5p-Targeted Inhibition of MSH6 via the TLR4/NF-κB Signaling Pathway.

Fusobacterium nucleatum (Fn) is significantly associated with poor prognosis in colorectal carcinoma (CRC), however, mechanisms of Fn in DNA mismatch repair (MMR) and microsatellite instability (MSI) in CRC have not been fully elucidated. Clinical samples are collected to analyze the relationship between Fn abundance and microsatellite stability. Tumor cells are treated with Fn to detect the expression of proteins related to toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (Myd88), mutS homolog 6 (MSH6), and nuclear factor-κB (NF-κB) signaling pathways, respectively. Combined with the prediction results from TargetScan, the regulatory role of microRNA upstream of MSH6 is demonstrated. The effect of this regulatory axis on CRC development is demonstrated using a nude mouse tumor model. Compared with microsatellite stability (MSS)-type CRC patients, MSI-type showed higher Fn abundance. Fn treatment of CRC cells activated TLR4/Myd88/NF-κB signaling pathway, transcriptionally activating miRNA-155-5p expression, thereby negatively regulating MSH6. Fn treatment accelerated the malignant progression of CRC in mice, and this process is inhibited by miRNA-155-5p antagomir. Fn in CRC upregulated miRNA-155-5p by activating TLR4/NF-κB signaling to inhibit MSH6, and this regulatory pathway may affect MSS of cancer cells.

Cytologic testing for mismatch repair deficiency/microsatellite instability and NTRK gene fusion is not routinely indicated in primary pancreaticobiliary carcinoma cell block material.

INTRODUCTION: Pancreaticobiliary carcinomas rarely harbor targetable genetic alterations, including microsatellite instability (MSI) or neurotrophic tyrosine receptor kinase (NTRK) gene fusions. As these malignancies are typically present at an advanced stage and have suboptimal response to chemotherapy, the discovery of an actionable genomic alteration provides an additional avenue of treatment for chemotherapy-refractory cases. MATERIALS AND METHODS: In this study, we evaluate 319 cases of pancreaticobiliary carcinoma diagnosed on fine-needle aspiration biopsy or biliary brushing for DNA mismatch repair (MMR) protein deficiency and pan-TRK overexpression by immunohistochemistry (IHC) and compare these results to MSI and NTRK gene fusion molecular testing. RESULTS AND CONCLUSION: Although we find a high concordance between MMR protein IHC and MSI molecular testing in the evaluation of MMR deficiency and between pan-TRK IHC and NTRK fusion testing by next-generation sequencing, the low prevalence of either of these genetic alterations in our cohort casts doubt on the value of screening cases of pancreaticobiliary carcinoma for MMR protein deficiency and NTRK fusions.

BRAF + EGFR +/- MEK inhibitors after immune checkpoint inhibitors in BRAF V600E mutated and deficient mismatch repair or microsatellite instability high metastatic colorectal cancer.

BACKGROUND: Immune checkpoint inhibitors (ICIs) are the guideline endorsed first choice for patients with deficient mismatch repair or microsatellite instability high (dMMR/MSI-H) mCRC, however a significant proportion experience primary or secondary resistance. BRAF V600E mutated (BRAFm) and dMMR/MSI-H mCRC can be treated with BRAF + EGFR inhibitors but specific data on the efficacy after progression to ICIs are missing. METHODS: We collected consecutive patients with BRAFm dMMR/MSI-H mCRC treated from 2017 to 2024 with a combination of BRAFi+EGFRi+/-MEKi, after disease progression on ICIs. A control cohort of BRAFm pMMR/MSS mCRC patients treated with encorafenib+cetuximab+/-binimetinib from 2nd line was used. RESULTS: dMMR/MSI-H (n = 50) BRAFm mCRC patients were more often > 70-year-old, with right-sided primary tumors, without liver but more lymphnode metastases than pMMR/MSS (n = 170). They were treated more frequently beyond 2nd line and 45 % were primary progressors to ICIs. Lower ORR (18 % versus 32 %, p = 0.09) and DCR (60 % versus 73 %, p = 0.11) was seen without reaching significance in dMMR/MSI-H as compared to pMMR/MSS patients. After a median follow-up of 14.04 months, no differences in PFS (median 5.13 versus 4.50 months, HR 0.83, 95 %CI: 0.57-1.20, p = 0.31) and OS (median 10.75 versus 9.11 months, HR 0.89, 95 %CI: 0.59-1.32, p = 0.55) were observed. CONCLUSIONS: Our results show that BRAFm dMMR/MSI-H mCRC patients benefit from BRAFi+EGFRi+/-MEKi after progression under ICIs. Despite lower ORR and DCR, the outcome is not different from that observed in pMMR/MSS BRAFm CRC and is in line with the results of the BEACON registration trial.