SEAMARK: phase II study of first-line encorafenib and cetuximab plus pembrolizumab for MSI-H/dMMR BRAFV600E-mutant mCRC

Patients with both BRAF V600E mutations and microsatellite instability-high (MSI-H)/mismatch repair-deficient (dMMR) metastatic colorectal cancer (mCRC) have poor prognosis. Currently, there are no specifically targeted first-line treatment options indicated for patients with mCRC whose tumors harbor both molecular aberrations. Pembrolizumab is a checkpoint inhibitor approved for the treatment of MSI-H/dMMR mCRC, and the BRAF inhibitor encorafenib, in combination with cetuximab, is approved for previously treated BRAF V600E-mutant mCRC. Combination of pembrolizumab with encorafenib and cetuximab may synergistically enhance antitumor activity in patients with BRAF V600E-mutant, MSI-H/dMMR mCRC. SEAMARK is a randomized phase II study comparing the efficacy of the combination of pembrolizumab with encorafenib and cetuximab versus pembrolizumab alone in patients with previously untreated BRAF V600E-mutant, MSI-H/dMMR mCRC.

Pancreatic cancer biomarkers: A pathway to advance in personalized treatment selection

Pancreatic cancer is one of the tumors with the worst prognosis, and unlike other cancers, few advances have been made in recent years. The only curative option is surgery, but only 15-20% of patients are candidates, with a high risk of relapse. In advanced pancreatic cancer there are few first-line treatment options and no validated biomarkers for better treatment selection. The development of targeted therapies in pancreatic cancer is increasingly feasible due to tumor-agnostic treatments, such as PARP inhibitors in patients with BRCA1, BRCA2 or PALB2 alterations or immunotherapies in patients with high microsatellite instability/tumor mutational burden. In addition, other therapeutic molecules have been developed for patients with KRAS G12C mutation or fusions in NTRK or NRG1. Consequently, there has been a growing interest in biomarkers that may help guide targeted therapy in pancreatic cancer. Therefore, this review aims to offer an updated perspective on biomarkers with therapeutic potential in pancreatic cancer.

Pembrolizumab in patients from China with microsatellite instability-high/mismatch repair deficient tumors: KEYNOTE-158

Aim: To evaluate pembrolizumab in patients of Chinese descent with microsatellite instability-high (MSI-H)/deficient mismatch repair (dMMR) tumors enrolled in KEYNOTE-158 (Cohort L). Methods: Patients with MSI-H/dMMR advanced tumors received pembrolizumab 200 mg IV Q3W. Primary end point was overall response rate (ORR). Secondary end points were duration of response (DOR), progression-free survival (PFS) and overall survival (OS). Results: 24 patients were enrolled (20 were evaluable for efficacy). With median follow-up of 12.4 months, the ORR was 70%. DOR, PFS and OS were all not reached. A total of 19 (79%) patients had a treatment-related adverse event (AE; grade ≥3 in 4 [17%]), and 8 (33%) had an immune-mediated AE (grade ≥3 in (4 [17%]). Conclusion: Pembrolizumab provided meaningful and durable responses with manageable safety. These results are consistent with those reported for the global trial.

Clinical evidence for efficacy of pembrolizumab in MSI-H and TMB-H advanced solid tumor: results from three cancer centers in China

BACKGROUND

Pembrolizumab has been indicated in the treatment of solid tumors with high frequency microsatellite instability (MSI-H) or high tumor mutational burden (TMB-H); however, real-world data on the effectiveness of pembrolizumab with or without chemotherapy in this molecular subset remain limited. Our retrospective study evaluated the clinical efficacy and safety of pembrolizumab in treating advanced solid tumors with either MSI-H or TMB-H.

METHODS

This retrospective study analyzed data from 116 patients with MSI-H or TMB-H advanced solid cancers who received pembrolizumab with or without chemotherapy regardless of treatment setting. We analyzed objective response rate (ORR) and progression-free survival (PFS).

RESULTS

The top three cancer types were colorectal (48.6% MSI-H, 6.5% TMB-H), lung (15.4% MSI-H, 84.4% TMB-H), and gastric (15.4% MSI-H, 5.1% TMB-H). The ORR with pembrolizumab was 52.6%, including complete response (CR) observed in 8.6% (n = 10) of cases and partial responses (PR) in 43.9% (n = 51). Of the 93 patients who received first-line pembrolizumab, 52 patients achieved objective response (10 CR, 42 PR), with a median PFS of 14.0 months (95% confidence intervals [CI] 6.6-21.4). Of the 23 who received subsequent-line pembrolizumab, the ORR was 39.1%, disease control rate was 91.3%, and median PFS was 5.7 months (95% CI 3.9-7.5). Treatment-related adverse events were observed in 32 patients (27.6%), with no reported treatment-related fatal adverse events.

CONCLUSION

Our study provides real-world evidence on the clinical effectiveness of pembrolizumab with or without chemotherapy in the treatment of patients with MSI-H and TMB-H advanced solid cancers.

Immunotherapy in mismatch repair-deficient metastatic colorectal cancer - Outcome and novel predictive markers

BACKGROUND

This study aims to assess predictive markers for response to immunotherapy in dMMR/MSI-H metastatic colorectal cancer (mCRC) patients.

MATERIALS AND METHODS

A study using two prospective cohorts from MD Anderson Cancer Center and Sheba Medical Center of consecutive patients with dMMR/MSI-H mCRC that were treated with immunotherapy between 2014-2022. Primary outcome was progression-free survival (PFS) and secondary outcome was overall response rate (ORR). Evaluated predictors included ECOG-PS score, RAS/BRAF status, single-agent versus doublet immunotherapy, metastatic sites, disease burden, and CEA levels prior to treatment initiation. Kaplan-Meier analysis and Cox proportional hazard regression model were used to analyze the effect of exposure variables on PFS.

RESULTS

The study included 153 patients. Median follow-up time was 26 months (IQR 11-48). Median PFS was 51.6 months (95%CI 38.1-NR) and ORR was 58.1%. In a univariate analysis, male sex was associated with worse PFS with a HR of 1.67 (95% CI 1.00-2.79); Right-sided tumors were associated with improved PFS with a HR of 0.56 (95% CI 0.32-0.97); Liver or lung metastasis were associated with worse PFS with HRs of 2.35 (95%CI 1.43-3.88) and 2.30 (95%CI 1.31-4.04), respectively; ECOG-PS score ≥ 2, CEA levels ˃5 μg/L prior to treatment initiation and ≥ 3 metastatic sites were associated with worse PFS with HRs of 2.09 (95%CI 0.98-4.47), 2.23 (95%CI 1.30-3.81) and 3.11 (95%CI 1.61-6.03), respectively. Liver or lung metastasis remained significant in a multivariable model.

CONCLUSIONS

Extent of disease (worse PFS with high CEA, poor ECOG-PS and ≥3 metastatic sites) and disease location (worse PFS with liver or lung metastasis and left sided tumor) were associated with immunotherapy outcome in dMMR/MSI-H mCRC.

Case report: Target and immunotherapy of a lung adenocarcinoma with enteric differentiation, EGFR mutation, and high microsatellite instability

Background

Pulmonary enteric adenocarcinoma (PEAC) is a rare histological subtype of non-small-cell lung cancer (NSCLC) with a predominant (>50%) enteric differentiation component. The frequency of high microsatellite instability (MSI-H) is very low in lung cancer. EGFR tyrosine kinase inhibitors and immunotherapy are standard treatment for NSCLC patients, but their effectiveness in lung adenocarcinoma with pulmonary enteric differentiation is unknown.

Case presentation

This report describes a 66-year-old man who was initially diagnosed with metastatic lung adenocarcinoma with EGFR mutation based on pleural fluid. A lung biopsy was obtained after 17 months of first-line icotinib treatment. Histological analysis of biopsy samples and endoscopic examination resulted in a diagnosis of adenocarcinoma with enteric differentiation. Next-generation sequencing of 1,021 genes showed EGFR E19del, T790M, and MSI-H, while immunohistochemical assay showed proficient expression of mismatch repair (MMR) proteins. Consequently, the patient was treated with osimertinib and had a progression-free survival (PFS) of 3 months. His treatment was changed to chemotherapy with/without bevacizumab for 6.5 months. Then, the patient was treated with one cycle of camrelizumab monotherapy and camrelizumab plus chemotherapy, respectively. The tumor continued to grow, and the patient suffered pneumonia, pulmonary fungal infections, and increased hemoptysis. He received gefitinib and everolimus and died 2 months later and had an overall survival of 30 months.

Conclusion

In summary, our case describes a rare pulmonary enteric adenocarcinoma with an EGFR-activating mutation and MSI-H, responding to an EGFR tyrosine kinase inhibitor and poorly benefiting from an immune checkpoint inhibitor.

The current status and prospect of immunotherapy in colorectal cancer

Metastatic colorectal cancer (mCRC) is a heterogeneous disease. We reviewed the current clinical trials on immunotherapy in metastatic colorectal cancer with high microsatellite instability and microsatellite stability. Owing to the advances in immunotherapy, its use has gradually expanded from second- and third-line therapies to first-line, early neoadjuvant, and adjuvant therapies. Based on current research results, immunotherapy has shown very good results in dMMR/MSI-H patients, whether it is neoadjuvant therapy for operable patients or first-line or multi-line therapy for advanced patients. KEYNOTE 016 study also showed that patients with MSS were basically ineffective in single immunotherapy. Moreover, immunotherapy for colorectal cancer may also require identification of new biomarkers.

Single-cell RNA-seq reveals characteristics in tumor microenvironment of PDAC with MSI-H following neoadjuvant chemotherapy with anti-PD-1 therapy

Accumulating evidence suggests the minority of patients with advanced pancreatic ductal adenocarcinoma (PDAC) that have microsatellite instability high (MSI-H) can benefit from immune checkpoint inhibitors (ICIs). However, the effects of ICIs on the tumor microenvironment (TME) of PDAC remain elusive. We conducted single-cell RNA-seq (scRNA-seq) analysis on a residual lesion from a MSI-H PDAC patient who received a radical operation after eight cycles of neoadjuvant treatment (nab-paclitaxel/gemcitabine plus pembrolizumab). Multiple tumor subclusters were identified in residual lesion after neoadjuvant treatment, one of which was mainly composed of cells in the S and G2M phases. This subcluster also had enriched expression of MKI67 and PCNA and cell cycle-related signatures and was thus defined as a proliferating tumor subcluster. This subcluster had higher S_score, Fatty acid_score, UPR_score, and Glycolysis_score than others. We also identified characteristics of the TME after neoadjuvant treatment by comparing the excised primary tumors form nontreated PDAC and the residual lesion. The residual lesion was characterized with activated pancreatic stellate cells (PSCs) and exhausted T cells (Tex). We compared the receptor-ligand interactions between the two groups, and found that no checkpoint receptor-ligand pairs between T cells and tumor cells were identified in the residual lesion, while there were many checkpoint receptor-ligand pairs in the nontreated primary PDAC. In conclusion, our findings revealed the characteristics of residual lesion of advanced PDAC with MSI-H upon combination treatment of chemotherapy and immunotherapy, which might provide some valuable clues for solving the puzzle of ICI in PDAC.

Lung Cancer in Patients With Lynch Syndrome: Association or Coincidence?

Lynch syndrome (LS), also known as hereditary nonpolyposis colorectal cancer (HNPCC) occurs due to microsatellite instability (MSI) caused by mutations in one of the mismatch repair genes leading to deficient mismatch repair proteins (dMMR). Although lung cancer is very common there is no established association between LS and lung cancer. In this manuscript we describe a case of lung cancer in a LS patient and then summarize available literature on this topic. Sixty seven y/o female patient with history of stage I colon and urothelial cancer, meeting the Amsterdam criteria, was diagnosed with LS on genetic testing. Sixteen years after the diagnosis of colon cancer, she was found to have adenocarcinoma of the lung with Next-generation sequencing (NGS) testing revealing the presence of germline mutation in MSH2 in the tumor cells indicating the possibility of LS driven lung cancer. However, subsequent immunohistochemistry (IHC) on tumor cells indicated proficient mismatch repair genes confirming the sporadic nature of lung cancer. On review of literature, we found that the coincidental presence of lung cancer in patients with LS can sometimes be mistaken for causation and may lead to confusion. Lynch syndrome associated tumors which are microsatellite instable (MSI) can be treated effectively with immunotherapy with durable responses, however, not all tumors in patient with LS are MSI impacting the choice of therapy.

Cost-effectiveness analysis of pembrolizumab versus chemotherapy as first-line treatment for mismatch-repair-deficient (dMMR) or microsatellite-instability-high (MSI-H) advanced or metastatic colorectal cancer from the perspective of the Chinese health-care system

BACKGROUND

Pembrolizumab is superior to chemotherapy as a first-line treatment for patients with mismatch-repair-deficient (dMMR) or microsatellite-instability-high (MSI-H) advanced or metastatic colorectal cancer (CRC), with a significant long-term survival benefit according to the KEYNOTE-177 trial. The current study aimed to determine whether pembrolizumab is a cost-effective treatment for patients with dMMR/MSI-H advanced or metastatic CRC in China.

METHODS

A partitioned survival model (PSM) was developed to simulate patients with dMMR/MSI-H advanced or metastatic CRC based on progression-free survival (PFS), progressive disease (PD) and death. The model was designed using a lifetime horizon, a 6-week cycle, and a 5% discount rate. The patients in the model had metastatic dMMR/MSI-H CRC and had not previously received treatment; these characteristics were similar to those of patients in KEYNOTE-177, a phase 3, open-label randomized clinical trial. The health outcomes and utilities were based on the KEYNOTE-177 trial and published data, respectively. Costs were calculated based on local charges (2022) and published literature. A treatment was deemed cost-effective in China if the incremental cost-effectiveness ratio (ICER) value was less than U.S.$38,142.56 per quality-adjusted life-year (QALY). The robustness of the results was assessed via one-way deterministic and probabilistic sensitivity analyses.

RESULTS

Baseline analysis revealed that pembrolizumab provided an additional 2.58 QALYs (3.00 life-year) at an incremental cost of U.S.$78,286.04, resulting in an ICER of U.S.$30,330.15 per QALY, which was below the willingness-to-pay threshold of U.S.$38,142.56 per QALY. When the patient assistance program (PAP) was considered, the ICER became U.S.$1,730.67 per QALY, manifesting absolute cost-effectiveness. The results of sensitivity analyses demonstrated that pembrolizumab was cost-effective in most cases.

CONCLUSIONS

Pembrolizumab is a cost-effective first-line treatment for dMMR/MSI-H advanced or metastatic CRC patients in China, especially considering the PAP.

Double Duty: Complete Pathologic Response of Two Colonic Primaries with Mosaicism of a Novel MLH1 Mutation to Neoadjuvant Pembrolizumab

We present a fascinating case of a 57-year-old male with a novel mutation in MLH1 (MLH1:c.1288G > T, p.(Glu430*)), who presented with two synchronous colonic tumours, initially deemed unresectable, and experienced a complete pathological response on neoadjuvant pembrolizumab. Extensive genetic testing revealed post-zygotic mosaicism from the novel mutation.

Case report: Remarkable response to a novel combination of mitotane, etoposide, paraplatin, and sintilimab in a patient with metastatic adrenocortical carcinoma

Background

Adrenocortical carcinoma (ACC) is a rare malignancy with a poor prognosis and limited treatment options for metastases. However, new effective regimens are emerging for specific conditions in metastatic ACC.

Case presentation

We report a case of a 36-year-old man diagnosed with metastatic ACC who had a large left adrenal mass (158 mm × 112 mm) and multiple metastases in the liver and lungs. Genetic testing revealed a microsatellite instability-high (MSI-H) tumor, a splice mutation in MLH1, and a high tumor mutational burden (TMB). After the left adrenalectomy, he received sequential treatment with a combination of mitotane, etoposide, paraplatin (EP-M), and sintilimab. His condition has been assessed as a stable disease since the sixth cycle of the combined regimen.

Conclusion

This case highlights the remarkable response of our patient's ACC with MSI-H tumor, MLH1 spice mutation, and high TMB to treatment with a novel combination of EP-M and sintilimab. Our findings suggest a promising therapeutic option for patients with similar molecular profiles.

The Significance of International Federation of Gynecology and Obstetrics Grading in Microsatellite Instability-High and POLE-Mutant Endometrioid Endometrial Carcinoma

With the advancement of diagnostic molecular technology and the molecular classification of endometrial endometrioid carcinoma (EEC), it remains to be seen whether conventional International Federation of Gynecology and Obstetrics (FIGO) grading retains clinical significance in certain molecular subtypes of EECs. In this study, we explored the clinical significance of FIGO grading in microsatellite instability-high (MSI-H) and POLE-mutant EECs. A total of 162 cases of MSI-H EECs and 50 cases of POLE-mutant EECs were included in the analysis. Significant differences in tumor mutation burden (TMB), progression-free survival, and disease-specific survival were seen between the MSI-H and POLE-mutant cohorts. Within the MSI-H cohort, there were statistically significant differences in TMB and stage at presentation across FIGO grades, but not survival. Within the POLE-mutant cohort, there was significantly greater TMB with increasing FIGO grade, but there were no significant differences in stage or survival. In both the MSI-H and POLE-mutant cohorts, log-rank survival analysis showed no statistically significant difference in progression-free and disease-specific survival across FIGO grades. Similar findings were also seen when a binary grading system was utilized. Since FIGO grade was not associated with survival, we conclude that the intrinsic biology of these tumors, characterized by their molecular profile, may override the significance of FIGO grading.

Genomic and Immune Features in an Intrahepatic Cholangiocarcinoma Patient with Microsatellite Instability-High Suffered Rapid Acquired Resistance to PD-1 Inhibitor

Introduction

Intrahepatic cholangiocarcinoma (ICC) is a highly aggressive liver malignancy with poor prognosis. Recently, the development of immune checkpoint inhibitors (ICIs), such as programmed cell death 1 (PD-1) inhibitors, has emerged as a promising strategy in multiple tumor types, including ICC. Microsatellite instability-high (MSI-H) is an important biomarker for ICIs in solid tumors. The response rate in patients with MSI-H is significantly higher than in those with microsatellite stability/microsatellite instability-low. And approximately 80-90% of the patients with MSI-H could maintain sustained clinical benefits once they had an initial response. However, some patients could have primary resistance at the beginning, and some might have acquired resistance after long-term treatment.

Case Presentation

We present the case of an ICC patient with MSI-H who suffered rapid progression after a short-term remission with camrelizumab, a kind of PD-1 inhibitor, as second-line treatment. The patient's genomic and immune features were analyzed by next-generation sequencing and multiplex immunofluorescence staining to explore the possible mechanisms of the rapidly acquired resistance of ICIs in this MSI-H case.

Conclusion

The genomic and immunohistochemical analysis showed that TGFBR2 mutation, loss of HLA B44 supertype, carrying B62 supertype, and increased PD-L1+ cells, macrophages, and Tregs in the tumor microenvironment might be related to the nonsustain benefit of ICIs in this MSI-H patient.

Phase I study of MSB2311, a novel pH-dependent anti-PD-L1 monoclonal antibody, treating patients with advanced solid tumors and lymphoma

MSB2311 is a novel pH-dependent humanized anti-programmed death-ligand 1 (PD-L1) monoclonal antibody. This phase I study primarily aimed to determine the maximum tolerated dose (MTD)/recommended phase 2 dose level (RP2D) of MSB2311 in patients with advanced solid tumors or lymphoma. MSB2311 was intravenously administered at 3, 10, and 20 mg/kg every 3 weeks (Q3W) and 10 mg/kg every 2 weeks (Q2W) using 3 + 3 design. During expansion phase, eligible patients with either PD-L1 overexpression, Epstein-Barr Virus positive, microsatellite instability high/mismatch repair deficient, or high tumor mutation burden tumors were treated at RP2D. A total of 37 Chinese patients were treated, including 31 with solid tumors and 6 lymphoma. No dose limiting toxicity was reported and MTD was not reached. The trial was expanded at 20 mg/kg Q3W or 10 mg/kg Q2W, both of which were determined as RP2D. Most common drug-related treatment-emergent adverse events were anemia (43.2%), aspartate aminotransferase increase (27.0%), proteinuria (21.6%), alanine aminotransferase increase and hypothyroidism (18.9% each), thyroid stimulating hormone increased and hyperglycemia (16.2% each). Out of 20 efficacy evaluable patients with biomarker positive solid tumors, 6 achieved confirmed partial response with the median duration of response of 11.0 months (95% CI 7.0-11.4) and 4 had stable disease, resulting an objective response rate of 30.0% (95% CI 11.9, 54.3) and disease control rate of 50.0% (95% CI 27.2, 72.8). One partial response was also observed among 6 patients with lymphoma. MSB2311 demonstrated a manageable safety profile and promising antitumor activity in patients with advanced solid tumors and lymphomas.

Immune escape and resistance to immunotherapy in mismatch repair deficient tumors

Up to 30% of colorectal, endometrial and gastric cancers have a deficiency in mismatch repair (MMR) protein expression due to either germline or epigenetic inactivation. Patients with Lynch Syndrome who inherit an inactive MMR allele have an up to 80% risk for developing a mismatch repair deficient (MMRd) cancer. Due to an inability to repair DNA, MMRd tumors present with genomic instability in microsatellite regions (MS). Tumors with high MS instability (MSI-H) are characterized by an increased frequency of insertion/deletions (indels) that can encode novel neoantigens if they occur in coding regions. The high tumor antigen burden for MMRd cancers is accompanied by an inflamed tumor microenvironment (TME) that contributes to the clinical effectiveness of anti-PD-1 therapy in this patient population. However, between 40 and 70% of MMRd cancer patients do not respond to treatment with PD-1 blockade, suggesting that tumor-intrinsic and -extrinsic resistance mechanisms may affect the success of checkpoint blockade. Immune evasion mechanisms that occur during early tumorigenesis and persist through cancer development may provide a window into resistance pathways that limit the effectiveness of anti-PD-1 therapy. Here, we review the mechanisms of immune escape in MMRd tumors during development and checkpoint blockade treatment, including T cell dysregulation and myeloid cell-mediated immunosuppression in the TME. Finally, we discuss the development of new therapeutic approaches to tackle resistance in MMRd tumors, including cancer vaccines, therapies targeting immunosuppressive myeloid programs, and immune checkpoint combination strategies.

Case Report: Chemoimmunotherapy in microsatellite-instability-high advanced goblet cell carcinoma of the colon

Background

Mismatch repair (MMR) deficiency is a fundamental factor affecting the management treatment outcomes of colorectal cancer (CRC). MMR status can be diagnosed by both immunohistochemistry (IHC) polymerase chain reaction (PCR). Since tumors with MMR deficiency are prone to respond to immunotherapy immune checkpoint inhibitors are used to treat such tumors.

Case presentation

A 69-year-old male patient presented to an outside clinic with weight loss and abdominal pain. Radiological investigations detected a mesenteric mass of 10 cm, peritoneal implants, and mediastinal lymphadenopathy. The eventual biopsy result from the mesenteric mass was mucinous adenocarcinoma with a goblet cell pattern. Since the IHC result was unclear for deficiency in mismatch repair (dMMR) metastatic CRC (mCRC), the diagnosis was confirmed with PCR. The patient received 8 cycles of FOLFIRINOX + bevacizumab followed by FOLFOX combined with pembrolizumab. No adverse effect was reported related to immunotherapy which resulted in radiologic and metabolic regression. The patient underwent cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (HIPEC). The final pathology results revealed a pathological complete response and R0 resection. In the 6th month follow-up, no recurrence or metastasis was reported.

Conclusion

Chemotherapy and immunotherapy combination is a promising treatment modality which can also be used for mCRC. This is the index case who received chemotherapy in combination with immunotherapy for mucinous adenocarcinoma of the colon with a goblet cell pattern and had pCR.

Case report: A combined immunotherapy strategy as a promising therapy for MSI-H colorectal carcinomas with multiple HPD risk factors

Approximately 5% of advanced colorectal carcinomas (CRCs) and 12-15% of early CRCs are microsatellite instability-high (MSI-H) or mismatch repair-deficient (dMMR) tumors. Nowadays, PD-L1 inhibitors or combined CTLA4 inhibitors are the major strategies for advanced or metastatic MSI-H colorectal cancer, but some people still show drug resistance or progression. Combined immunotherapy has been shown to expand the benefit population in non-small-cell lung carcinoma (NSCLC), hepatocellular carcinoma (HCC), and other tumors while reducing the incidence of hyper-progression disease (HPD). Nevertheless, advanced CRC with MSI-H remains rare. In this article, we describe a case of an elder patient with MSI-H advanced CRC carrying MDM4 amplification and DNMT3A co-mutation who responded to sintilimab plus bevacizumab and chemotherapy as the first-line treatment without obvious immune-related toxicity. Our case provides a new treatment option for MSI-H CRC with multiple risk factors of HPD and highlights the importance of predictive biomarkers in personalized immunotherapy.

Real-world treatment patterns and clinical outcomes for chemotherapy-based regimens in first-line MSI-H/dMMR metastatic colorectal cancer

MICRO ABSTRACT

This retrospective observational study assessed real-world treatment patterns and clinical outcomes among first-line MSI-H/dMMR metastatic colorectal cancer patients. Of 150 patients in the study cohort, 38.7% were treated with chemotherapy and 61.3% with chemotherapy + EGFR/VEGF inhibitor (EGFRi/VEGFi). Clinical outcomes were better among patients who received chemotherapy + EGFR/VEGF inhibitor than those who received chemotherapy.

INTRODUCTION

Prior to pembrolizumab approval in first-line (1L) treatment of MSI-H/dMMR metastatic colorectal cancer (mCRC), patients were managed with chemotherapy with or without an EGFRi or VEGFi, agnostic of biomarker testing or mutation status. This study assessed real-world treatment patterns and clinical outcomes among 1L MSI-H/dMMR mCRC patients treated with standard of care (SOC).

PATIENTS AND METHODS

Retrospective observational evaluation of patients ≥18 years diagnosed with stage IV MSI-H/dMMR mCRC who received community-based oncology care. Eligible patients were identified (01-Jun-2017 - 29-Feb-2020) and followed longitudinally until 31-Aug-2020/the last patient record/date of death. Descriptive statistics and Kaplan-Meier analyses were conducted.

RESULTS

Of 150 1L MSI-H/dMMR mCRC patients, 38.7% were treated with chemotherapy and 61.3% with chemotherapy + EGFRi/VEGFi. Accounting for censoring, the overall median real-world time to treatment discontinuation (95% CI) was 5.3 (4.4, 5.8) months; 3.0 (2.1, 4.4) and 6.2 (5.5, 7.6) months in the chemotherapy and chemotherapy + EGFRi/VEGFi cohorts, respectively. The combined median overall survival was 27.7 (23.2, not reached [NR]) months; 25.3 (14.5, NR) and 29.8 (23.2, NR) months in the chemotherapy and chemotherapy + EGFRi/VEGFi cohorts, respectively. The overall median real-world progression-free survival was 6.8 (5.3, 7.8) months; 4.2 (2.8, 6.1) and 7.7 (6.1, 10.2) months in the chemotherapy and chemotherapy + EGFRi/VEGFi cohorts, respectively.

CONCLUSIONS

1L MSI-H/dMMR mCRC patients receiving chemotherapy with EGFRi/VEGFi had better outcomes than those receiving only chemotherapy. An unmet need and opportunity to improve outcomes exists in this population that may be addressed by newer treatments like immunotherapies.

Perioperative Tailored Treatments for Gastric Cancer: Times Are Changing

Resectable gastric or gastroesophageal (G/GEJ) cancer is a heterogeneous disease with no defined molecularly based treatment strategy. Unfortunately, nearly half of patients experience disease recurrence despite standard treatments (neoadjuvant and/or adjuvant chemotherapy/chemoradiotherapy and surgery). In this review, we summarize the evidence of potential tailored approaches in perioperative treatment of G/GEJ cancer, with a special focus on patients with human epidermal growth factor receptor-2(HER2)-positive and microsatellite instability-high (MSI-H) tumors. In patients with resectable MSI-H G/GEJ adenocarcinoma, the ongoing INFINITY trial introduces the concept of non-operative management for patients with complete clinical-pathological-molecular response, and this could be a novel and potential practice changing strategy. Other pathways involving vascular endothelial growth factor receptor (VEGFR), fibroblast growth factor receptor (FGFR), claudin18 isoform 2 (CLDN18.2), and DNA damage repair proteins are also described, with limited evidence until now. Although tailored therapy appears to be a promising strategy for resectable G/GEJ cancer, there are several methodological issues to address: inadequate sample size for pivotal trials, underestimation of subgroup effects, and choice of primary endpoint (tumor-centered vs. patient-centered endpoints). A better optimization of G/GEJ cancer treatment allows maximizing patient outcomes. In the perioperative phase, although caution is mandatory, times are changing and tailored strategies could introduce new treatment concepts. Overall, MSI-H G/GEJ cancer patients possess the characteristics to be the subgroup that could receive the most benefit from a tailored approach.

Association of KMT2C/D loss-of-function variants with response to immune checkpoint blockades in colorectal cancer

Immune checkpoint inhibitors (ICIs) have become important treatment strategies, yet responses vary among patients and predictive biomarkers are urgently needed. Mutations in KMT2C and KMT2D lead to increased levels of genomic instability. Therefore, we aimed to examine whether KMT2C/D mutations might be a predictor of immunotherapeutic efficacy. Here, we investigated the associations of KMT2C/D loss-of-function (LOF) variants with tumor mutation burden (TMB), MSI-H, PD-L1 expression, the levels of tumor-infiltrating leukocytes (TILs), and clinical response to ICIs. It was found that KMT2C/D LOF variants were associated with higher TMB. Compared with the non-LOF group, the proportion of patients with MSI-H tumors was larger in the LOF group. PD-L1 expression was higher in the LOF group only for colorectal cancer in both the Chinese and The Cancer Genome Atlas cohorts. Importantly, KMT2C/D LOF variants were associated with decreased regulatory T cells and increased levels of CD8⁺ T cells, activated NK cells, M1 macrophages, and M2 macrophages in colorectal cancer. However, there was no significant association between KMT2C/D LOF and TILs levels in other cancer types. Consistently, the results showed that KMT2C/D LOF variants were associated with prolonged overall survival only in colorectal cancer (p = 0.0485). We also presented that patients with KMT2C/D LOF mutations exhibited a better clinical response to anti-PD-1 therapy in a Chinese colorectal cancer cohort (p = 0.002). Taken together, these results suggested that KMT2C/D LOF variants could be a useful predictor for ICIs efficacy in colorectal cancer. In addition, the predictive value of KMT2C/D LOF variants was consistent with their association with TILs levels.

Case report: Complete pathologic response with first-line immunotherapy combination in a young adult with massive liver dissemination of mismatch repair-deficient metastatic colorectal cancer: Immunological and molecular profiling

The current level of evidence for immunotherapy in previously untreated microsatellite unstable metastatic colorectal cancer is based on recent pieces of evidence of few studies that demonstrated durable response and clinical benefit, in terms of objective response rate, disease control rate, and progression-free survival in this subgroup of patients. On the basis of combinatorial immunotherapy with nivolumab plus ipilimumab, we report the exceptional case of a complete pathological response in a 21-year-old woman presenting a clinically aggressive stage IV colorectal cancer with massive nodal and liver involvement. Extensive molecular analyses based on whole genome next-generation DNA sequencing, RNA sequencing, fluorescent multiplex immunohistochemistry, and flow cytometry provided a detailed description of tumoral and immunological characteristics of this noteworthy clinical case.

Fusobacterium nucleatum load in MSI colorectal cancer subtypes

BACKGROUND

Fusobacterium nucleatum (F. nucleatum) infection may lead to colorectal cancer (CRC) development in the context of microsatellite instability (MSI). To date, however, the relationship between F. nucleatum load and MSI CRC subtypes has not been clarified.

METHODS

One hundred seventy-nine consecutive patients with CRC were enrolled in the present study. In 94 patients with MSI CRC, 32 had hereditary MSI CRC from Lynch syndrome, 62 had sporadic MSI CRC, while the remaining 85 had microsatellite stable (MSS) CRC. The association of the F. nucleatum load with each CRC subtype and the patients' clinicopathological characteristics was examined.

RESULTS

Of the 179 patients with CRC, 158 (88.3%) were F. nucleatum-positive. A high F. nucleatum load was found in 84.4% (27/32), 96.8% (60/62), and 83.5% (71/85) of the patients with hereditary MSI CRC, sporadic MSI CRC, and MSS CRC, respectively (P = 0.024). In terms of clinicopathological features, a high F. nucleatum load was significantly associated with female, right-sided CRC, BRAF V600E, CpG island methylator phenotype-positive CRC, and MSI CRC (P = 0.008, P = 0.015, P = 0.007, P = 0.006, and P < 0.001, respectively). However, the clinicopathological characteristics did not differ significantly by F. nucleatum load between hereditary and sporadic MSI CRCs without tumor depth.

CONCLUSIONS

The F. nucleatum load was higher in hereditary MSI CRC than in MSS CRC as well as sporadic MSI CRC. These findings may contribute to preventing CRC in hereditary MSI CRC through appropriate intervention.

PD-1 inhibitor in combination with fruquintinib therapy for initial unresectable colorectal cancer: A case report

BACKGROUND

PD-1 inhibitors in combination with fruquintinib have not previously been reported as neoadjuvant therapy for patients with colorectal cancer. In this case report, the combination of a PD-1 inhibitor and fruquintinib demonstrated good efficacy in patients with MSI-H colorectal cancer.

CASE SUMMARY

The patient was a young man in his 30s who had MSI-H type colon cancer. The patient underwent four cycles of neoadjuvant therapy with a PD-1 inhibitor combined with fruquintinib before surgery, resulting in regression of the mass and a successful surgery.

CONCLUSION

Some patients with colorectal cancer have the MSI-H type, and the first-line chemotherapy regimen is not effective. However, PD-1 monoclonal antibody immunotherapy has a good therapeutic effect, which can be improved by combination therapy with fruquintinib. We recommend that patients with a history of colon or rectal cancer receive universal MSI testing; then, neoadjuvant therapy should be used.

Histopathologic and Genetic Features of Mismatch Repair-Deficient High-Grade Prostate Cancer

AIMS

Mismatch repair (MMR) deficiency is commonly caused by functional inactivation of MLH1, PMS2, MSH2 or MSH6. The morphologic and molecular correlates of MMR deficiency have been extensively characterized in certain tumor types such as colorectal and endometrial adenocarcinoma. In contrast, the histologic and molecular features of MMR-deficient prostate cancer remain incompletely described. In this study, we evaluated 19 MMR-deficient prostate cancers, including 11 cases without prior systemic treatment.

METHODS AND RESULTS

All treatment-naïve cases (11/11, 100%) were Grade Group 4-5 and had predominant cribriform and/or solid growth patterns. Solid components (any amount) and tumor infiltrating lymphocytes were seen in 7/11 (64%) of these cases each. In 68 MMR-proficient Grade Group 5 prostate cancers, predominant cribriform or solid growth patterns, solid components (any amount) and tumor infiltrating lymphocytes were seen at significantly lower frequencies (31/68, 46%; 9/68, 13% and 6/62, 9%, respectively; p<0.001 for all comparisons). Molecular evaluation of 19 cases demonstrated that MMR-deficiency was secondary to functional loss of MSH2/MSH6 and MLH1/PMS2 in 15 cases (79%) and 4 cases (21%), respectively. Definite or likely germline mutations were present in 4 cases (4/19, 21%). TMPRSS2::ERG rearrangements were identified in 2 cases (2/19, 11%). Recurrent cancer-relevant somatic mutations included (but were not limited to) ATM, TP53, FOXA1, RB1, BRCA2 and PTEN.

CONCLUSIONS

MMR deficiency was most commonly secondary to inactivation of MSH2/MSH6 in this study. Importantly, MMR-deficient high-grade prostatic adenocarcinomas had morphologic features that might be useful to identify selected cases for MMR IHC.

Impact of tissue-agnostic approvals for patients with sarcoma

Tissue-agnostic drug development is a major step forward in offering treatment options for rare tumors. Sarcomas are heterogeneous rare malignancies with more than 100 subtypes. Recent failure of Phase III trials, nonbiomarker-driven clinical trials, and rarity hamper developmental therapeutics in sarcomas. Since a 'one-size-fits-all' approach continues to be the standard of care, tissue-agnostic approvals assume significance in sarcomas. In this review, we focus on the clinical evidence of recent drug approvals for neurotrophic tyrosine receptor kinase (NTRK) fusion, microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR) phenotype, and tumor mutation burden-high (TMB-H) status in the context of sarcomas, and the future landscape of tissue-agnostic targets, such as rearranged during transfection (RET), fibroblast growth factor receptor (FGFR), and neuregulin-1 (NRG1).

Lynch Syndrome and MSI-H Cancers: From Mechanisms to "Off-The-Shelf" Cancer Vaccines

Defective DNA mismatch repair (dMMR) is associated with many cancer types including colon, gastric, endometrial, ovarian, hepatobiliary tract, urinary tract, brain and skin cancers. Lynch syndrome - a hereditary cause of dMMR - confers increased lifetime risk of malignancy in different organs and tissues. These Lynch syndrome pathogenic alleles are widely present in humans at a 1:320 population frequency of a single allele and associated with an up to 80% risk of developing microsatellite unstable cancer (microsatellite instability - high, or MSI-H). Advanced MSI-H tumors can be effectively treated with checkpoint inhibitors (CPI), however, that has led to response rates of only 30-60% despite their high tumor mutational burden and favorable immune gene signatures in the tumor microenvironment (TME). We and others have characterized a subset of MSI-H associated highly recurrent frameshift mutations that yield shared immunogenic neoantigens. These frameshifts might serve as targets for off-the-shelf cancer vaccine designs. In this review we discuss the current state of research around MSI-H cancer vaccine development, its application to MSI-H and Lynch syndrome cancer patients and the utility of MSI-H as a biomarker for CPI therapy. We also summarize the tumor intrinsic mechanisms underlying the high occurrence rates of certain frameshifts in MSI-H. Finally, we provide an overview of pivotal clinical trials investigating MSI-H as a biomarker for CPI therapy and MSI-H vaccines. Overall, this review aims to inform the development of novel research paradigms and therapeutics.

Cancer Therapy Guided by Mutation Tests: Current Status and Perspectives

The administration of many cancer drugs is tailored to genetic tests. Some genomic events, e.g., alterations of EGFR or BRAF oncogenes, result in the conformational change of the corresponding proteins and call for the use of mutation-specific compounds. Other genetic perturbations, e.g., HER2 amplifications, ALK translocations or MET exon 14 skipping mutations, cause overproduction of the entire protein or its kinase domain. There are multilocus assays that provide integrative characteristics of the tumor genome, such as the analysis of tumor mutation burden or deficiency of DNA repair. Treatment planning for non-small cell lung cancer requires testing for EGFR, ALK, ROS1, BRAF, MET, RET and KRAS gene alterations. Colorectal cancer patients need to undergo KRAS, NRAS, BRAF, HER2 and microsatellite instability analysis. The genomic examination of breast cancer includes testing for HER2 amplification and PIK3CA activation. Melanomas are currently subjected to BRAF and, in some instances, KIT genetic analysis. Predictive DNA assays have also been developed for thyroid cancers, cholangiocarcinomas and urinary bladder tumors. There is an increasing utilization of agnostic testing which involves the analysis of all potentially actionable genes across all tumor types. The invention of genomically tailored treatment has resulted in a spectacular improvement in disease outcomes for a significant portion of cancer patients.

Immune cells and signatures characterize tumor microenvironment and predict outcome in ovarian and endometrial cancers

Aims: We investigated immunogenomic signatures and correlated them with survival in ovarian cancer (OV) and endometrial cancer (EC). Materials & method: We used whole transcriptome sequencing data from uterine serous cancer and The Cancer Genome Atlas data of OV and EC (n = 719). Gene expression score was calculated. Population abundance of immune cells were estimated. Results: TGF-β, myeloid cells, IFN-γ, T cells, B cells and endothelial cells predicted overall survival. Whereas CD47, neutrophils and endothelial cells predicted progression-free survival. In multivariate analyses, TGF-β, CD47 and monocytic cells predicted survival in high levels of microsatellite instability (MSI-H) EC whereas high IFN-γ trended toward improved survival in the MSI-S EC. High IFN-γ/low TGF-β and high IFN-γ/low CD47 signatures predicted longer overall survival. Low TGF-β/low CD47 signature predicted longer overall survival only in the MSI-H EC. Conclusion: Our data support the role of immune markers in predicting survival in OV/EC.

Can hypoxia-inducible factor-1α overexpression discriminate human colorectal cancers with different microsatellite instability?

Clinicopathological features of high-frequency microsatellite instability (MSI-H) colorectal cancers (CRCs) are different from low-frequency MSI (MSI-L) and microsatellite stable (MSS) CRCs. The clinical features of MSI-L cases are unknown, and although the tumors usually show instability for dinucleotide markers, evaluation based on dinucleotides alone could lead to the misclassification of MSI-L or MSS as MSI-H. In this research, we investigated the usefulness of hypoxia-inducible factor-1α (HIF-1α) expression to discriminate MSI-L from MSS and MSI-H in human CRC. Tumor tissue from 94 CRC patients was used to determine the expression level of HIF-1α mRNA and HIF-1α protein using quantitative real-time PCR and immunohistochemistry analyses, respectively. The results indicated that HIF-1α mRNA and HIF-1α protein levels were upregulated in CRC patients compared with controls (P < 0.0001). Average HIF-1α expression in tissues with advanced stages and grades was also higher than that in earlier stages and grades. Expression of HIF-1α mRNA varied between CRC patients with different types of microsatellite instability (MSS, MSI-L and MSI-H). Taken together, our findings provide preliminary evidence that HIF-1α expression level in CRC tumors correlates with different MSI categories. HIF-1α expression may therefore represent a novel marker to separate the MSI-L group from the MSS and MSI-H groups.

Microsatellite Instability and Effectiveness of Adjuvant Treatment in pT1N1 Gastric Cancer: A Multicohort Study

BACKGROUND

Microsatellite status is a prognostic biomarker in advanced gastric cancer. This retrospective study aimed to investigate the usefulness of microsatellite status in predicting prognosis and response to adjuvant treatment in pT1N1 gastric cancer.

PATIENTS AND METHODS

Among 875 patients who underwent radical gastrectomy for pT1N1 gastric cancer at two tertiary hospitals, 838 with available microsatellite instability (MSI) data were included and classified into two groups according to microsatellite status: microsatellite stable (MSS) and MSI-high (MSI-H). Recurrence-free survival rate and risk factors for tumor recurrence were analyzed.

RESULTS

Of 838 gastric cancer patients, 100 (11.9%) were MSI-H and 307 (36.6%) received adjuvant treatment. During median follow-up of 70 months, 42 (5.0%) patients experienced gastric cancer recurrence; hematogenous recurrences were the most common (45.2%). Recurrence-free survival was similar in the MSS and MSI-H groups (p = 0.27), and adjuvant treatment did not show an oncological benefit over surgery alone for pT1N1 gastric cancer (p = 0.53). On univariate analysis, age, operation period, and Lauren classification were significantly associated with tumor recurrence, while adjuvant treatment and MSI status were not associated with tumor recurrence. On multivariate analysis, MSI status was not associated with tumor recurrence, and adjuvant treatment worsened the tumor recurrence risk [hazard ratio (HR) 2.373, 95% confidence interval (CI) 1.125-5.006, p = 0.023).

CONCLUSION

MSI status may not be a prognostic factor for tumor recurrence or a predictor of response to adjuvant treatment in pT1N1 gastric cancer patients. Considering that the effect of adjuvant treatment to decrease the risk of tumor recurrence is not clear, it may not be indicated in pT1N1 patients.

Poor performance status patient with long-lasting major response to pembrolizumab in advanced non-small-cell lung cancer with coexisting POLE mutation and deficient mismatch repair pathway

Immunotherapy with immune checkpoint inhibitors (ICIs) represents a major breakthrough in lung cancer treatment. For patients with advanced non-small-cell lung cancer (NSCLC) and poor performance status (PS), the availability of sensitivity markers to immune-checkpoint inhibitors (ICI) would be useful for attending physicians and assist them in their decision-making process. Deficient mismatch repair (dMMR) can lead to high microsatellite instability (MSI-H) and coexist with mutations in polymerase proofreading (DNA polymerase Epsilon POLE and delta 1 POLD1) with a specific mutational signature. This would result in high tumor mutational burden and programmed cell death protein ligand 1 (PD-L1) overexpression. We report herein on a NSCLC case with MSI-H and POLE mutation in a patient with inaugural poor general condition, who exhibited prolonged response to anti-programmed cell death protein (PD-1) therapy. Additionally, there was a marked improvement of the patient's performance status, from PS 3 before ICI administration to PS 1 upon ICI therapy.

Comparing immunotherapies to other frequently used treatments of gastric cancer

Introduction: Although standard doublet chemotherapy represents the upfront gold standard to increase survival and improve quality of life of gastric cancer patients, overall improvements in long-term outcomes are modest and novel treatments are urgently needed. Among these, immunotherapy is an increasingly attractive option.Areas covered: A number of clinical trials have shown that checkpoint inhibitors may be of value, but many unclear issues remain controversial and should be promptly untangled. In our short review, we offer the current available data regarding immunotherapies in gastric cancers, discuss potential limits of the reported trials, compare outcomes of checkpoints inhibitor to those of standard chemotherapy or other novel treatments, and present basic principles of immune surveillance and immune escape that may be embraced in the near future with novel drug combinations.Expert opinion: Gastric cancer patients may benefit from immunotherapy, both given alone in advanced lines and upfront in combination with chemotherapy. We believe that appropriate patients' and tumor's selection are crucial issues to maximize its potential efficacy. In addition, we think that assay standardization, biomarker agreement, and translational studies will improve the benefit-to-risk ratio of these agents in the clinical practice.

Association of the Lung Immune Prognostic Index with Immunotherapy Outcomes in Mismatch Repair Deficient Tumors

Background: MSI-H/dMMR is considered the first predictive marker of efficacy for immune checkpoint inhibitors (ICIs). However, around 39% of cases are refractory and additional biomarkers are needed. We explored the prognostic value of pretreatment LIPI in MSI-H/dMMR patients treated with ICIs, including identification of fast-progressors. Methods: A multicenter retrospective study of patients with metastatic MSI-H/dMMR tumors treated with ICIs between April 2014 and May 2019 was performed. LIPI was calculated based on dNLR > 3 and LDH > upper limit of normal. LIPI groups were good (zero factors), intermediate (one factor) and poor (two factors). The primary endpoint was overall survival (OS), including the fast-progressor rate (OS < 3 months). Results: A total of 151 patients were analyzed, mainly female (59%), with median age 64 years, performance status (PS) 0 (42%), and sporadic dMMR status (68%). ICIs were administered as first or second-line for 59%. The most frequent tumor types were gastrointestinal (66%) and gynecologic (22%). LIPI groups were good (47%), intermediate (43%), and poor (10%). The median follow-up was 32 months. One-year OS rates were 81.0%, 67.1%, and 21.4% for good, intermediate, and poor-risk groups (p < 0.0001). After adjustment for tumor site, metastatic sites and PS, LIPI remained independently associated with OS (HR, poor-LIPI: 3.50, 95%CI: 1.46-8.40, p = 0.02. Overall, the fast-progressor rate was 16.0%, and 35.7% with poor-LIPI vs. 7.5% in the good-LIPI group (p = 0.02). Conclusions: LIPI identifies dMMR patients who do not benefit from ICI treatment, particularly fast-progressors. LIPI should be included as a stratification factor for future trials.

Tetranucleotide and Low Microsatellite Instability Are Inversely Associated with the CpG Island Methylator Phenotype in Colorectal Cancer

Simple Summary

A type of DNA mismatch repair defect known as “elevated microsatellite alterations at selected tetranucleotide repeats” (EMAST) is found across many different cancers. Tetranucleotide microsatellite instability, which is caused by MSH3 mismatch repair gene/protein loss-of-function, shares a molecular basis with “low microsatellite instability” (MSI-L) in colorectal cancer. Tetranucleotide microsatellite instability is also a byproduct of “high microsatellite instability” (MSI-H) that arises from deficiency of mismatch repair due to MSH2, MSH6, MLH1 or PMS2 gene alterations. MSH3-related EMAST is emerging as a biomarker of poor prognosis in colorectal cancer and needs to be clearly differentiated from MSI-H. Here, we show that tumours with non-MSI-H-related EMAST or MSI-L rarely show concordant promoter methylation of multiple marker genes. Colorectal tumours that are positive for a single (1/5) tetranucleotide repeat marker are an important subset of the EMAST spectrum.

Abstract

MSH3 gene or protein deficiency or loss-of-function in colorectal cancer can cause a DNA mismatch repair defect known as “elevated microsatellite alterations at selected tetranucleotide repeats” (EMAST). A high percentage of MSI-H tumors exhibit EMAST, while MSI-L is also linked with EMAST. However, the distribution of CpG island methylator phenotype (CIMP) within the EMAST spectrum is not known. Five tetranucleotide repeat and five MSI markers were used to classify 100 sporadic colorectal tumours for EMAST, MSI-H and MSI-L according to the number of unstable markers detected. Promoter methylation was determined using methylation-specific PCR for MSH3, MCC, CDKN2A (p16) and five CIMP marker genes. EMAST was found in 55% of sporadic colorectal carcinomas. Carcinomas with only one positive marker (EMAST-1/5, 26%) were associated with advanced tumour stage, increased lymph node metastasis, MSI-L and lack of CIMP-H. EMAST-2/5 (16%) carcinomas displayed some methylation but MSI was rare. Carcinomas with ≥3 positive EMAST markers (13%) were more likely to have a proximal colon location and be MSI-H and CIMP-H. Our study suggests that EMAST/MSI-L is a valuable prognostic and predictive marker for colorectal carcinomas that do not display the high methylation phenotype CIMP-H.

Defining the current role of immune checkpoint inhibitors in the treatment of mismatch repair-deficient/microsatellite stability-high colorectal cancer and shedding light on future approaches

Introduction: Mismatch repair deficient (MMR-D)/microsatellite instability-high (MSI-H) colorectal cancer (CRC) carries unique biologic features including high tumor mutation burden, increased amount of mutation-associated neoantigen generation, and the presence of marked tumor-infiltrating lymphocytes. Immune checkpoint inhibitor (ICI) therapy has rapidly changed the treatment algorithm of MMR-D/MSI-H CRC.Areas covered: In this review article, we discuss the recent data regarding the use of ICIs in metastatic MMR-D/MSI-H CRC patients. We also elaborated on potential biomarkers of ICI response and innovative therapeutic approaches that may prevail resistance mechanisms for the treatment of MMR-D/MSI-H colorectal cancer.Expert opinion: Pembrolizumab was recently granted approval by the FDA as first-line therapy for metastatic MMR-D/MSI-H CRC based on the results of the Keynote 177 study. The combination of nivolumab and ipilimumab will also likely be a choice for the initial therapy of MMR-D/MSI-H CRC in the near future. More therapeutic modalities with novel immunomodulatory agents as well as targeted therapy directed to immune resistance pathways are needed. The novel approaches discussed in this review article will define potential treatment options for the management of MMR-D/MSI-H CRC patients who progress on first-line ICI therapy.

General treatment for metastatic colorectal cancer: From KEYNOTE 177 study

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In the palliative treatment of metastatic colorectal cancer(mCRC), doublet chemotherapy (FOLFOX or FOLFIRI) or triplet chemotherapy (FOLFOXIRI) combined with targeted drugs (cetuximab or bevacizumab) is the main regimen. Recently, microsatellite instability-high (MSI-H)/ DNA mismatch repair deficient (dMMR) was discovered as a biomarker to distinguish immunotherapy benefited populations. In this context, recent published randomized phase III clinical trials tested the efficacy and safety of immunotherapy and traditional chemotherapy with or without targeted drugs as first-line treatment for mCRC patients with MSI-H/dMMR.

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In this manuscript, we briefly analyze this article and further discuss immune monotherapy or double immunotherapy for mCRC patients with MSI-H/dMMR, the immunotherapy for patients with BRAF V600E mutant mCRC, and the immunotherapy for mCRC patients with microsatellite stable.

In the palliative treatment of metastatic colorectal cancer (mCRC), doublet chemotherapy (FOLFOX or FOLFIRI) or triplet chemotherapy (FOLFOXIRI) combined with targeted drugs (cetuximab or bevacizumab) is the main regimen. Recently, microsatellite instability-high (MSI-H) or DNA mismatch repair deficient (dMMR) was discovered as a biomarker to distinguish immunotherapy-benefited populations. In this context, recently published randomized phase III clinical trials tested the efficacy and safety of immunotherapy and traditional chemotherapy with or without targeted drugs as first-line treatment for patients with MSI-H/dMMR mCRC.

Here, we briefly analyze this article and further discuss immune monotherapy or double immunotherapy for patients with MSI-H/dMMR mCRC, the immunotherapy for patients with BRAF V600E mutant mCRC, and the immunotherapy for patients with microsatellite stable mCRC.

Tumor-Infiltrating Lymphoid Cells in Colorectal Cancer Patients with Varying Disease Stages and Microsatellite Instability-High/Stable Tumors

Immune checkpoint inhibition is an effective anti-cancer therapeutic approach but has shown limited efficacy in treating colorectal cancer (CRC) patients. Importantly, immune constituents of the tumor microenvironment (TME) can influence therapy response and cancer progression. We investigated the expression of immune checkpoints (ICs) on lymphoid populations within the CRC TME and compared with cells from normal colon tissues using samples from 50 patients with varying disease stages. We found that the levels of B cells, T cells, and NK cells were similar, IC-expressing CD4⁺ and CD4⁺CD8⁺ double positive T cells were higher, while CD8⁺ T cells and CD4⁻CD8⁻ double negative T cells were significantly lower in CRC tumors. Notably, patients with mismatch-repair deficiency/microsatellite instability-high tumors had higher levels of IC-expressing CD4⁺ and CD8⁺ T cells than patients with proficient MMR and microsatellite stable tumors. Lastly, The Cancer Genome Atlas Colon Adenocarcinoma datasets showed associations between low expression of selective genes and poorer progression-free interval. Our findings highlight differential expression of ICs on lymphoid cells in CRC tumors in the era of cancer immunotherapy, which at present is solely approved for anti-PD-1 therapy in patients with dMMR/MSI-H tumors. Further investigations into their functionality have potentials for deciphering resistance mechanisms to IC inhibition.

Rare BRCA2 Mutation and MSI-H in Male Patient with Aggressive Stage III Colorectal Cancer, Case Report and Literature Review

Colorectal cancer is the third most common malignancy worldwide. We report the case of a 66-year-old man diagnosed with stage III B colorectal cancer who underwent radical surgery, adjuvant chemotherapy and subsequently developed hepatic metastases. Two months following metastasectomy, PET-CT scan revealed liver metastases with metabolic activity. The patient was started on FOLFIRI chemotherapy regimen in combination with cetuximab, and achieved stable partial remission 7 weeks after starting the treatment. NGS and IHC testing of the surgically removed tumor revealed MSI-H/dMMR, and NRAS/KRAS wild type status, moderate positive (30%) expression of PD-L1 protein, along with BRCA2 mutation.

Current Microsatellite Instability Testing in Management of Colorectal Cancer

Colorectal cancer (CRC) is the third most common cancer worldwide. In the past decade, mismatch repair deficiency (dMMR), manifested as microsatellite instability-high (MSI-H), has been recognized as a distinct mechanism promoting tumorigenesis in 15% of CRCs including 3% Lynch syndrome and 12% sporadic CRCs. As the molecular classifications of CRCs are continuously evolving, MSI-H CRCs appear to be the most homogeneous CRCs with distinct molecular, morphologic, and clinical features. MSI-H CRCs have dMMR causing MSI-H and genetic hypermutation but with diploid chromosomes. Morphologically, MSI-H CRCs appear as poorly differentiated or mucinous adenocarcinoma with characteristic lymphocytic infiltration. Most importantly, MSI-H CRCs have better stage-adjusted survival, do not respond well to standard 5-fluorouracil-based adjuvant chemotherapy, but do respond to immunotherapy. The United States Food and Drug Administration granted accelerated approval to immune checkpoint inhibitors, anti-programmed cell death protein-1 antibodies pembrolizumab and nivolumab, and the combination of nivolumab with anti-CTLA4 antibody ipilimumab for the second-line treatment of patients with stage IV MSI-H CRCs in 2017. There are still ongoing phase III clinical trials evaluating pembrolizumab and anti-programmed death-ligand 1 antibody atezolizumab as the first-line treatment in stage IV MSI-H CRCs and a phase I study on the combination of nivolumab and ipilimumab in patients with early stage CRC. These ongoing clinical studies on immunotherapy may lead to practice-changing results in the management of MSI-H CRCs. The National Comprehensive Cancer Network 2018 guidelines recommended MSI to be tested in all newly diagnosed CRCs. The MSI test will become increasingly vital in guiding adjuvant chemotherapy and immunotherapy in the management of CRCs.

Incidence of microsatellite instability-high hepatocellular carcinoma among Japanese patients and response to pembrolizumab

AIM

Pembrolizumab has been quickly approved in many countries for the treatment of patients with unresectable or metastatic, microsatellite instability-high (MSI-H) solid tumors, which have progressed following previous treatment and who have no satisfactory alternative treatment options. We aimed to determine the incidence of MSI-H tumors in Japanese patients with advanced hepatocellular carcinoma (HCC).

METHODS

We investigated the incidence of MSI-H tumors in 82 consecutive Japanese patients with unresectable HCC that had progressed after standard of care treatment. Using a companion diagnostic sequencing kit (polymerase chain reaction analysis of five microsatellite markers: BAT25, BAT26, NR21, NR24 and MONO27), we analyzed 49 biopsy specimens and 33 resection specimens. Responses to pembrolizumab were assessed with the modified Response Evaluation Criteria in Solid Tumors.

RESULTS

MSI-H tumors were found in only two patients (2.4%), in whom all five markers showed slight shortening. One patient had a complete response to pembrolizumab for over 10 months, and the other was a non-responder.

CONCLUSIONS

MSI-H tumor status was found in only two of 82 (2.4%) Japanese patients with advanced HCC, one of whom had a complete response to pembrolizumab. Thus, MSI status should be assessed in patients with HCC who progress after standard of care treatment.

The Role of Anti-Angiogenics in Pre-Treated Metastatic BRAF-Mutant Colorectal Cancer: A Pooled Analysis

Background. FOLFOXIRI plus Bevacizumab is one of the most frequently used first-line treatments for patients with BRAF-mutant colorectal cancer (CRC), while second-line treatment requires extensive further research. In this pooled analysis, we evaluate the impact of anti-angiogenics in patients with pre-treated BRAF-mutant CRC. Methods. We monitored patients in randomized, controlled studies who had advanced CRC and were undergoing second-line chemotherapy in addition to utilizing Bevacizumab, Ramucirumab or Aflibercept treatments. These data were pooled together with the data and results of BRAF-mutant patients enrolled in two phase III trials (TRIBE and TRIBE-2 study), who had been treated with second-line treatment both with or without Bevacizumab. Overall survival (OS), in relation to BRAF mutational status, was the primary focus. Results. Pooled analysis included 129 patients. Anti-angiogenics were found to have a significant advantage over the placebo in terms of OS (HR 0.50, 95%CI 0.29-0.85) (p = 0.01). Conclusions. Our pooled analysis confirms the efficacy of anti-angiogenics in pre-treated BRAF-mutant CRC, establishing the combination of chemotherapy plus Bevacizumab or Ramucirumab or Aflibercept as a valid treatment option.

The Clinicopathological Features and Genetic Mutations in Gastric Cancer Patients According to EMAST and MSI Status

Background: There has been no report regarding the clinicopathological features and genetic mutations regarding elevated microsatellite alterations at selected tetranucleotide repeats (EMAST) in gastric cancer (GC). Methods: The correlation among EMAST status, microsatellite instability (MSI) status, mutations of common GC-related genes and 16 DNA repair-associated genes, and the clinicopathological features were analyzed. Results: Among the 360 GC patients enrolled, there were 76 (21.1%) with EMAST+ tumors and 284 with EMAST− tumors, and 59 (16.4%) were MSI-high (MSI-H) tumors, and 301 were microsatellite stable (MSS) tumors. Patients with EMAST+ tumors exhibited an earlier pathological T category and had more genetic mutations in the PI3K/AKT pathway, ARID1A and DNA repair-associated genes than those with EMAST− tumors. Patients with MSI-H tumors have more genetic mutations in the PI3K/AKT pathway and DNA repair-associated genes than those with MSS tumors. In the subgroup analysis for MSI-H GC, EMAST+ tumors were associated with earlier pathological T and N categories, earlier TNM stages, higher frequency of DNA-repair-associated genetic mutations, and a better survival rate than EMAST− tumors. Conclusions:PI3K/AKT pathway mutations may play an important role in EMAST+ and/or MSI-H GC. EMAST+/MSI-H tumors seem to represent a different subtype of gastric cancer from EMAST−/MSI-H tumors.

Clinical Development of Immunotherapy for Deficient Mismatch Repair Colorectal Cancer

Colorectal cancer (CRC) is the second most common cause of cancer-related death in the United States. Despite excellent prognosis for early stage disease, 5-year survival rates in metastatic disease remain low. A small subset of CRC is defined by a deficiency in mismatch repair (dMMR) resulting in high levels of microsatellite instability and are responsive to immunotherapy. Immune checkpoint inhibitors (ICIs) targeting the programmed death 1 (PD-1)/programmed death ligand 1 axis and cytotoxic T-lymphocyte antigen 4 have been explored and show robust clinical outcomes with prolonged progression-free survivals in nonrandomized single-arm clinical trials. On the basis of these data, single-agent therapy with pembrolizumab and nivolumab and combination therapy with nivolumab/ipilimumab have been approved by the US Food and Drug Administration for metastatic CRC that has progressed after treatment with fluoropyrimidine, oxaliplatin, and irinotecan. Ongoing clinical trials are exploring the use of these agents in earlier lines of therapy such as first-line metastatic therapy and adjuvant therapy for stage III CRC. However, resistance to ICIs does occur in a subset of patients and ongoing clinical trials are exploring novel approaches in these PD-1-refractory patients. The aim of this review is to outline the development and decision-making of ICIs in the treatment of dMMR CRC and to discuss ongoing clinical trials in this therapeutic space.

Pancytopenia And Limbic Encephalopathy Complicating Immunotherapy For Clear Cell Endometrial Cancer With Microsatellite Instability-High (MSI-H)

Background

Clear cell carcinoma of the endometrium (CCE) has a tendency to occur in a mismatch repair protein deficient molecular background. Treatment with immunotherapy can predict a favorable response.

Case presentation

We are presenting a 53-year-old female, diagnosed with CCE 17 years ago, who was treated initially with hysterectomy and left salpingo-oophorectomy, who relapsed a few months later, and was then treated with left pelvic mass excision and sigmoidectomy. Recently, the disease recurred as a retroperitoneal lymphadenopathy, which was resected but then relapsed locally, spread to the lungs, and progressed further after three lines of chemotherapy. On pathological review of the tumor, it was found to harbor loss of nuclear expression of MLH-1 and PMS-2. Based on a strong predictor of response to immunotherapy, pembrolizumab was tried. However, within a few days of the single dose of pembrolizumab, immune thrombocytopenia followed by pancytopenia, recurrent seizures, visual hallucination, and cerebellar signs consistent with limbic encephalitis developed, which were not responding to steroid and intravenous immunoglobulin.

Conclusion

We are presenting a case of a CCE with deficient mismatch repair that developed two autoimmune side effects, pancytopenia and limbic encephalitis, within a few days of a single injection of pembrolizumab.

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Precision medicine for metastatic colorectal cancer: an evolving era

Introduction: Metastatic colorectal cancer (CRC) remains a dilemma for cancer researchers with an increasing incidence in the younger patient population. Until the last decade, limited therapeutic options were available for metastatic CRC patients leading to relatively poor clinical outcomes.Areas covered: With advances in genome sequencing technology and reductions in the cost of next-generation sequencing, molecular profiling has become more accessible for cancer researchers and clinical investigators, which has furthered our understanding of the molecular behavior of CRC. This progress has recently translated into significant advances in molecular-based therapeutics and led to the development of new target-specific agents in metastatic CRC patients. In this review article, we extensively elaborate on genomic alterations seen in CRC patients including, but not limited to, EGFR, MMR, BRAF, HER2, NTRKs, FGFR, BRCA1/2, PALB2, POLE, and POLD1 genes, all of which are potentially actionable by either an FDA-approved agent or in a clinical trial setting.Expert opinion: We strongly recommend molecular profiling in metastatic CRC patients during the early course of their disease, as this may provide therapeutic and prognostic information that can guide clinicians to practice precision medicine. Patients with potentially actionable genes should be considered for targeting agents based on molecular alterations.

Japan Society of Clinical Oncology provisional clinical opinion for the diagnosis and use of immunotherapy in patients with deficient DNA mismatch repair tumors, cooperated by Japanese Society of Medical Oncology, First Edition

Background

Novel therapeutic agents have improved survival outcomes in patients with advanced solid tumors. In parallel, the development of predictive biomarkers to identify patients who are likely to benefit from a certain treatment has also contributed to the improvement of survival. Recently, clinical trials have reported the efficacy of immune checkpoint inhibitors in the treatment of mismatch repair-deficient (dMMR) advanced solid tumors. In Japan, a PD-1 inhibitor for dMMR advanced solid tumors, regardless of the primary tumor site, has been approved. However, there are some issues related to administering immune checkpoint inhibitors in the clinical practice setting, making it necessary to develop the guidelines.

Methods

Clinical questions (CQs) regarding medical care were formulated for patients with dMMR advanced solid tumors, and evidence to the CQs was collected by manual search to prepare recommendations. Then, the committee members voted to determine the level of each recommendation considering the strength of evidence, expected risks and benefits to patients, and other factors.

Results

The current guideline, which we consider a provisional clinical opinion at this point, describes the 11 requirements to be considered in terms of patients for whom dMMR testing is recommended, the timing and methods of dMMR testing, and clinical care systems required to perform dMMR testing properly and to administer immune checkpoint inhibitors safely.

Conclusion

This provisional clinical opinion proposes the requirements for performing dMMR testing properly to select patients who are likely to benefit from immune checkpoint inhibitors and administering them safely.

Electronic supplementary material

The online version of this article (10.1007/s10147-019-01498-8) contains supplementary material, which is available to authorized users.