Outcomes of Chemotherapy for Microsatellite Instable-High Metastatic Colorectal Cancers

Precision Medicine in the Era of Genetic Testing: Microsatellite Instability Evolved

The recognized importance of microsatellite instability (MSI) in cancer has evolved considerably in the past 30 years. From its beginnings as a molecular predictor for Lynch syndrome, MSI first transitioned to a universal screening test in all colorectal and endometrial cancers, substantially increasing the identification of patients with Lynch syndrome among cancer patients. More recently, MSI has been shown to be a powerful biomarker of response to immune checkpoint blockade therapy across a diversity of tumor types, and in 2017 was granted Food and Drug Administration approval as the first tumor histology-agnostic biomarker for a cancer therapy. Focusing on colorectal cancer specifically, immune checkpoint blockade therapy has been shown to be highly effective in the treatment of both MSI-high (MSI-H) colon and rectal cancer, with data increasingly suggesting an early role for immune checkpoint blockade therapy in MSI-H colorectal tumors in the neoadjuvant setting, with the potential to avoid more toxic and morbid approaches using traditional chemotherapy, radiation therapy, and surgery. The success of MSI as an immune checkpoint blockade target has inspired ongoing vigorous research to identify new similar targets for immune checkpoint blockade therapy that may help to one day expand the reach of this revolutionary cancer therapy to a wider swath of patients and indications.

Comparative effectiveness of immunotherapy and chemotherapy in patients with metastatic colorectal cancer stratified by microsatellite instability status

BACKGROUND

Immunotherapy have demonstrated promising outcomes in patients with high microsatellite instability (MSI) (MSI-H) metastatic colorectal cancer. However, the comparative effectiveness of Immunotherapy and chemotherapy for patients with low MSI (MSI-L), and microsatellite stable (MSS) metastatic colorectal cancer remains unclear.

AIM

To investigate immunotherapy vs chemotherapy for treatment of MSI-L/MSS metastatic colorectal cancer, and to evaluate the success of immunotherapy against chemotherapy in managing MSI-H metastatic colorectal cancer during a follow-up of 50 months.

METHODS

We conducted a retrospective cohort study using the National Cancer Database (NCDB) to evaluate the overall survival (OS) of patients with metastatic colorectal cancer treated with immunotherapy or chemotherapy. The study population was stratified by MSI status (MSI-H, MSI-L, and MSS). Multivariable Cox proportional hazard models were used to assess the association between treatment modality and OS, adjusting for potential confounders.

RESULTS

A total of 21951 patients with metastatic colorectal cancer were included in the analysis, of which 2358 were MSI-H, and 19593 were MSI-L/MSS. In the MSI-H cohort, immunotherapy treatment (n = 142) was associated with a significantly improved median OS compared to chemotherapy (n = 860). After adjusting for potential confounders, immunotherapy treatment remained significantly associated with better OS in the MSI-H cohort [adjusted hazard ratio (aHR): 0.57, 95% confidence interval (95%CI): 0.43-0.77, P < 0.001]. In the MSS cohort, no significant difference in median OS was observed between immunotherapy treatment and chemotherapy (aHR: 0.94, 95%CI: 0.69-1.29, P = 0.715).

CONCLUSION

In this population-based study using the NCDB, immunotherapy treatment was associated with significantly improved OS compared to chemotherapy in patients with MSI-H metastatic colorectal cancer, but not in those with MSI-L/MSS metastatic colorectal cancer. Further studies are warranted to determine the optimal therapeutic approach for patients with MSI-L/MSS metastatic colorectal cancer.

Efficacy and safety of natural killer cells injection combined with XELOX chemotherapy in postoperative patients with stage III colorectal cancer in China: a prospective randomised controlled clinical trial study protocol

BACKGROUND

Colorectal cancer (CRC) is the second most frequently diagnosed cancer and the fifth leading cause of cancer-related death in China. However, resistance to multiple chemotherapeutics after surgery leads to failure of the main therapy to CRC. Natural killer (NK) cells are innate cytotoxic lymphocytes that exhibit strong cytotoxic activity against tumour cells. NK cell-based therapy, either alone or in combination with chemotherapy, has achieved favourable results and holds promise for addressing recurrence and metastasis in CRC patients after surgery.

METHODS AND ANALYSIS

This is a prospective, randomised controlled clinical trial to evaluate efficacy and safety of interleukin 2 activated NK cells injection combined with XELOX (capecitabine plus oxaliplatin)-based chemotherapy for postoperative CRC patients. Participants will be randomly divided into treatment group and control group, and every group includes 40 patients. The treatment group will also receive NK cells (5×109) with+XELOX-based chemotherapy, while the control group will receive only XELOX-based chemotherapy. This treatment will be repeated for eight cycles (6 months). The follow-up period lasts about 3 years, during which CEA, CA19-9, CA125, enhancement CT and colonoscopy will be conducted. The primary endpoints of this study are progression-free survival and overall survival, while the secondary endpoint is safety (number and severity of adverse events). Additionally, we aim to identify cancer stem cells in peripheral blood and predictive biomarkers (cytokines secreted by NK cells and activated markers of NK cells) that indicate patients who achieve an effective response.

ETHICS AND DISSEMINATION

The study has been approved by the Clinical Research Ethics Committee of our hospital (approval number 2023LLSC006) and the Chinese Clinical Trials. It will be conducted in accordance with the Declaration of Helsinki. Written informed consent will be obtained from all participants. The study findings will be submitted to peer-reviewed journals for publication.

TRIAL REGISTRATION NUMBER

Chinese Clinical Trials Registry (ChiCTR2300075861).

Genomic profile and clinical features of MSI-H and TMB-high pancreatic cancers: real-world data from C-CAT database

BACKGROUND

Microsatellite instability high (MSI-H) and tumor mutational burden high (TMB-high) pancreatic cancer are rare, and information is lacking. Based on the C-CAT database, we analyzed the clinical and genomic characteristics of patients with these subtypes.

METHODS

We retrospectively reviewed data on 2206 patients with unresectable pancreatic adenocarcinoma enrolled in C-CAT between July 2019 and January 2022. The clinical features, proportion of genomic variants classified as oncogenic/pathogenic in C-CAT, overall response rate (ORR), disease control rate (DCR), and time to treatment failure (TTF) of chemotherapy as first-line treatment were evaluated.

RESULTS

Numbers of patients with MSI-H and TMB-high were 7 (0.3%) and 39 (1.8%), respectively. All MSI-H patients were TMB-high. MSI-H and TMB-high patients harbored more mismatch repair genes, such as MSH2, homologous recombination-related genes, such as ATR and BRCA2, and other genes including BRAF, KMT2D, and SMARCA4. None of the 6 MSI-H patients who received chemotherapy achieved a clinical response, including 4 patients treated with gemcitabine plus nab-paclitaxel (GnP) therapy, whose DCR was significantly lower than that of microsatellite stable (MSS) patients (0 vs. 67.0%, respectively, p = 0.01). Among the TMB-high and TMB-low groups, no significant differences were shown in ORR, DCR (17.1 vs. 23.1% and 57.1 vs. 63.1%, respectively), or median TTF (25.9 vs. 28.0 weeks, respectively) of overall first-line chemotherapy.

CONCLUSIONS

MSI-H and TMB-high pancreatic cancers showed some distinct genomic and clinical features from our real-world data. These results suggest the importance of adapting optimal treatment strategies according to the genomic alterations.

Microsatellite Instability and Metastatic Colorectal Cancer - A Clinical Perspective

Approximately 4-5% of patients with metastatic colorectal cancer (mCRC) have mismatch repair deficient (dMMR)/microsatellite instability-high (MSI-H) tumours. These tumours present challenges in the clinical practice due to variant response to fluoropyrimidine-based chemotherapy and, perhaps, also non-immunologic targeted therapies. Recently, a breakthrough in the treatment of dMMR/MSI-H mCRC has been achieved with several clinical trials showing dramatic long-term benefit of immunotherapy using checkpoint inhibitors. Nevertheless, several questions remain regarding the optimisation of immunotherapy regimens and the use of biomarkers to identify populations set to derive the greatest benefit from immunotherapy. Combination regimens and/or the use of immunotherapy as a maintenance after induction non-immunologic systemic therapy may be the way forward to improve outcomes.

Artificial intelligence for detection of microsatellite instability in colorectal cancer-a multicentric analysis of a pre-screening tool for clinical application

BACKGROUND

Microsatellite instability (MSI)/mismatch repair deficiency (dMMR) is a key genetic feature which should be tested in every patient with colorectal cancer (CRC) according to medical guidelines. Artificial intelligence (AI) methods can detect MSI/dMMR directly in routine pathology slides, but the test performance has not been systematically investigated with predefined test thresholds.

METHOD

We trained and validated AI-based MSI/dMMR detectors and evaluated predefined performance metrics using nine patient cohorts of 8343 patients across different countries and ethnicities.

RESULTS

Classifiers achieved clinical-grade performance, yielding an area under the receiver operating curve (AUROC) of up to 0.96 without using any manual annotations. Subsequently, we show that the AI system can be applied as a rule-out test: by using cohort-specific thresholds, on average 52.73% of tumors in each surgical cohort [total number of MSI/dMMR = 1020, microsatellite stable (MSS)/ proficient mismatch repair (pMMR) = 7323 patients] could be identified as MSS/pMMR with a fixed sensitivity at 95%. In an additional cohort of N = 1530 (MSI/dMMR = 211, MSS/pMMR = 1319) endoscopy biopsy samples, the system achieved an AUROC of 0.89, and the cohort-specific threshold ruled out 44.12% of tumors with a fixed sensitivity at 95%. As a more robust alternative to cohort-specific thresholds, we showed that with a fixed threshold of 0.25 for all the cohorts, we can rule-out 25.51% in surgical specimens and 6.10% in biopsies.

INTERPRETATION

When applied in a clinical setting, this means that the AI system can rule out MSI/dMMR in a quarter (with global thresholds) or half of all CRC patients (with local fine-tuning), thereby reducing cost and turnaround time for molecular profiling.

Update on the role of pembrolizumab in patients with unresectable or metastatic colorectal cancer

Colorectal cancer (CRC) is the third most common cancer type in both men and women in the USA. Most patients with CRC are diagnosed as local or regional disease. However, the survival rate for those diagnosed with metastatic disease remains disappointing, despite multiple treatment options. Cancer therapies for patients with unresectable or metastatic CRC are increasingly being driven by particular biomarkers. The development of various immune checkpoint inhibitors has revolutionized cancer therapy over the last decade by harnessing the immune system in the treatment of cancer, and the role of immunotherapy continues to expand and evolve. Pembrolizumab is an anti-programmed cell death protein 1 immune checkpoint inhibitor and has become an essential part of the standard of care in the treatment regimens for multiple cancer types. This paper reviews the increasing evidence supporting and defining the role of pembrolizumab in the treatment of patients with unresectable or metastatic CRC.

Immunology of Lynch Syndrome

PURPOSE OF REVIEW

Patients with Lynch syndrome have a high probability of developing colorectal and other carcinomas. This review provides a comprehensive assessment of the immunologic aspects of Lynch syndrome pathogenesis and provides an overview of potential immune interventions for patients with Lynch syndrome polyps and Lynch syndrome-associated carcinomas.

RECENT FINDINGS

Immunogenic properties of the majority of Lynch syndrome polyps and associated cancers include microsatellite instability leading to a high mutational burden and the development of novel frameshift peptides, i.e., neoantigens. In addition, patients with Lynch syndrome develop T cell responses in the periphery and in the tumor microenvironment (TME) to tumor-associated antigens, and a proinflammatory cytokine TME has also been identified. However, Lynch syndrome lesions also possess immunosuppressive entities such as alterations in MHC class I antigen presentation, TGFβ receptor mutations, regulatory T cells, and upregulation of PD-L1 on tumor-associated lymphocytes. The rich immune microenvironment of Lynch syndrome polyps and associated carcinomas provides an opportunity to employ the spectrum of immune-mediating agents now available to induce and enhance host immune responses and/or to also reduce immunosuppressive entities. These agents can be employed in the so-called prevention trials for the treatment of patients with Lynch syndrome polyps and for trials in patients with Lynch syndrome-associated cancers.

Precision Medicine for the Management of Therapy Refractory Colorectal Cancer

In this analysis, we examined the efficacy, feasibility, and limitations of molecular-based targeted therapies in heavily pretreated metastatic colorectal cancer (mCRC) patients after failure of all standard treatments. In this single-center, real-world retrospective analysis of our platform for precision medicine, we mapped the molecular profiles of 60 mCRC patients. Tumor samples of the patients were analyzed using next-generation sequencing panels of mutation hotspots, microsatellite instability testing, and immunohistochemistry. All profiles were reviewed by a multidisciplinary team to provide a targeted treatment recommendation after consensus discussion. In total, we detected 166 mutations in 53 patients. The five most frequently found mutations were TP53, KRAS, APC, PIK3CA, and PTEN. In 28 cases (47% of all patients), a molecularly targeted therapy could be recommended. Eventually, 12 patients (20%) received the recommended therapy. Six patients (10%) had a clinical benefit. The median time to treatment failure was 3.1 months. Our study demonstrates the feasibility and applicability of using targeted therapies in daily clinical practice for heavily pretreated mCRC patients. This could be used as a targeted treatment option in half of the patients.

Experience of mismatch repair/microsatellite instability (MMR/MSI) testing among patients with advanced/metastatic colorectal cancer in the US

Objective: We assessed knowledge and awareness of MMR/MSI testing among advanced/metastatic CRC patients in the US who had previously taken the test.Methods: A non-interventional, cross-sectional online survey was conducted among 150 US CRC patients invited through a research panel. Eligible patients had to be ≥18 years, with stage III or IV CRC (self-reported), had undergone MMR/MSI testing for CRC in past 12 months and could recall the test, and provided informed consent. Descriptive analyses were performed.Results: 81.3% of patients received MMR/MSI testing information from their doctor. Of 64.7% of patients who were a member of a patient support group, 86.6% received information from their groups. Most patients (82.7%) also searched for information on their own (internet searches). Most patients (93.5 to 96.9%) were satisfied with information received from these sources. Reasons for having testing done included increasing knowledge about their cancer (69.3%), being beneficial to determining treatment options (60.7%), and doctor recommendation (62.7%). Key barriers to testing included personal reservations regarding benefits of the test (29.3%), insurance coverage (27.3%), and out-of-pocket costs (18.7%); 45.3% reported no barriers.Conclusions: Patients were well informed about MMR/MSI testing. Increased education of testing benefits and addressing financial barriers may help to further improve testing rates.

Immunotherapy in Metastatic Colorectal Cancer: Could the Latest Developments Hold the Key to Improving Patient Survival?

Immunotherapy has considerably increased the number of anticancer agents in many tumor types including metastatic colorectal cancer (mCRC). Anti-PD-1 (programmed death 1) and cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) immune checkpoint inhibitors (ICI) have been shown to benefit the mCRC patients with mismatch repair deficiency (dMMR) or high microsatellite instability (MSI-H). However, ICI is not effective in mismatch repair proficient (pMMR) colorectal tumors, which constitute a large population of patients. Several clinical trials evaluating the efficacy of immunotherapy combined with chemotherapy, radiation therapy, or other agents are currently ongoing to extend the benefit of immunotherapy to pMMR mCRC cases. In dMMR patients, MSI testing through immunohistochemistry and/or polymerase chain reaction can be used to identify patients that will benefit from immunotherapy. Next-generation sequencing has the ability to detect MSI-H using a low amount of nucleic acids and its application in clinical practice is currently being explored. Preliminary data suggest that radiomics is capable of discriminating MSI from microsatellite stable mCRC and may play a role as an imaging biomarker in the future. Tumor mutational burden, neoantigen burden, tumor-infiltrating lymphocytes, immunoscore, and gastrointestinal microbiome are promising biomarkers that require further investigation and validation.