Clinical impact of microsatellite instability in colon cancer following adjuvant FOLFOX therapy

Biomarkers for chemotherapy and drug resistance in the mismatch repair pathway

Drugs targeting DNA repair have developed rapidly in cancer therapy, and numerous inhibitors have already been utilized in preclinical and clinical stages. To optimize the selection of patients for treatment, it is essential to discover biomarkers to anticipate chemotherapy response. The DNA mismatch repair (MMR) pathway is closely correlated with cancer susceptibility and plays an important role in the occurrence and development of cancers. Here, we give a concise introduction of the MMR genes and focus on the potential biomarkers of chemotherapeutic response and resistance. It has been clarified that the status of MMR may affect the outcome of chemotherapy. However, the specific underlying mechanisms as well as contradictory results continue to raise considerable controversy and concern. In this review, we summarize the current literature to provide a general overview.

Synchronous Recto-Sigmoid Colorectal Carcinomas With Microsatellite Instability and an Activating PIK3CA Mutation

Synchronous colorectal cancer is a rare subtype of colorectal carcinoma defined by the presence of 2 or more primary tumors simultaneously or within 6 months of initial detection. The overall impact of a synchronous presentation on prognosis is not yet clear. Surgical resection is the primary treatment. However, higher rates of local recurrence and metastasis in synchronous colorectal cancer demand greater exploration of the role of adjuvant therapy. The increased frequency of microsatellite instability observed in synchronous colorectal cancer also affects therapy selection. Similarly, activating PIK3CA mutations are regularly noted in colorectal cancer, but their role in a synchronous presentation has not yet been described. We report a case of a young patient with a synchronous recto-sigmoid colorectal carcinoma complicated by microsatellite instability and an activating PIK3CA mutation—a presentation as of yet unreported in literature. We also review the impact of these molecular events on the efficacy of several chemotherapies and targeted therapies.

Prognostic and predictive value of microsatellite instability status among patients with colorectal cancer

Objectives: Compare overall survival (OS) between microsatellite instability (MSI) high and MSI-stable and analyze the effect of chemotherapy on OS. Methods: National cancer database was queried for patients diagnosed with colorectal adenocarcinoma between 2010 and 2016. We evaluated the OS and the chemotherapy effect using Kaplan-Meier estimates and multivariate Cox regression analyses. Results: Total of 30,436 stage II patients and 30,302 stage III patients were included. In stage II with high-risk features and MSI-high, patients who received chemotherapy had better OS compared to patients who didn't receive chemotherapy. The same was found in stage II with no high-risk features and MSI-high group. Conclusion: Stage II colorectal cancer patients with high-risk features and MSI-high who received chemotherapy have better OS compared to patients who didn't receive chemotherapy.

Predictive biomarkers for 5-fluorouracil and oxaliplatin-based chemotherapy in gastric cancers via profiling of patient-derived xenografts

Gastric cancer (GC) is commonly treated by chemotherapy using 5-fluorouracil (5-FU) derivatives and platinum combination, but predictive biomarker remains lacking. We develop patient-derived xenografts (PDXs) from 31 GC patients and treat with a combination of 5-FU and oxaliplatin, to determine biomarkers associated with responsiveness. When the PDXs are defined as either responders or non-responders according to tumor volume change after treatment, the responsiveness of PDXs is significantly consistent with the respective clinical outcomes of the patients. An integrative genomic and transcriptomic analysis of PDXs reveals that pathways associated with cell-to-cell and cell-to-extracellular matrix interactions enriched among the non-responders in both cancer cells and the tumor microenvironment (TME). We develop a 30-gene prediction model to determine the responsiveness to 5-FU and oxaliplatin-based chemotherapy and confirm the significant poor survival outcomes among cases classified as non-responder-like in three independent GC cohorts. Our study may inform clinical decision-making when designing treatment strategies.

Rate of dissemination and prognosis in early and advanced stage colorectal cancer based on microsatellite instability status: systematic review and meta-analysis

INTRODUCTION

For the past two decades, microsatellite instability (MSI) has been reported as a robust clinical biomarker associated with survival advantage attributed to its immunogenicity. However, MSI is also associated with high-risk adverse pathological features (poorly differentiated, mucinous, signet cell, higher grade) and exhibits a double-edged sword phenomenon. We performed a systematic review and meta-analysis to evaluate the rate of dissemination and the prognosis of early and advanced stage colorectal cancer based on MSI status.

METHODS

A systematic literature search of original studies was performed on Ovid searching MEDLINE, Embase, Cochrane Database of Systematic Reviews, American College of Physicians ACP Journal Club, Database of Abstracts of Reviews of Effects DARE, Clinical Trials databases from inception of database to June 2019. Colorectal cancer, microsatellite instability, genomic instability and DNA mismatch repair were used as key words or MeSH terms. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline was followed. Data were pooled using a random-effects model with odds ratio (OR) as the effect size. Statistical analysis was performed using RevMan ver 5.3 Cochrane Collaboration.

RESULTS

From 5288 studies, 136 met the inclusion criteria (n = 92,035; MSI-H 11,746 (13%)). Overall, MSI-H was associated with improved OS (OR, 0.81; 95% CI 0.73-0.90), DFS (OR, 0.73; 95% CI 0.66-0.81) and DSS (OR, 0.69; 95% CI 0.52-0.90). Importantly, MSI-H had a protective effect against dissemination with a significantly lower rate of lymph node and distant metastases. By stage, the protective effect of MSI-H in terms of OS and DFS was observed clearly in stage II and stage III. Survival in stage I CRC was excellent irrespective of MSI status. In stage IV CRC, without immunotherapy, MSI-H was not associated with any survival benefit.

CONCLUSIONS

MSI-H CRC was associated with an overall survival benefit with a lower rate of dissemination. Survival benefit was clearly evident in both stage II and III CRC, but MSI-H was neither a robust prognostic marker in stage I nor stage IV CRC without immunotherapy.

A Simple, Accurate and Cost-Effective Capillary Electrophoresis Test with Computational Methods to Aid in Universal Microsatellite Instability Testing

Background: Microsatellite instability (MSI) testing is important for the classification of Lynch syndrome, as a prognostic marker and as a guide for adjuvant chemotherapy in colorectal cancer (CRC). The gold standard for determining MSI status has traditionally been fluorescent multiplex polymerase chain reaction (PCR) and capillary gel electrophoresis (CGE). However, its use in the clinical setting has diminished and has been replaced by immunohistochemical (IHC) detection of loss of mismatch repair protein expression due to practicability and cost. The aim of this study was to develop a simple, cost-effective and accurate MSI assay based on CGE. Method: After amplification of microsatellites by polymerase chain reaction (PCR) using the National Cancer Institute (NCI) panel (BAT 25, BAT26, D5S346, D2S123, D17S250) of MSI markers, parallel CGE was utilized to classify colorectal cancers as MSI-H, MSI-L and MSS using the 5200 Fragment Analyzer System. Cell lines and patient cancer specimens were tested. DNA from 56 formalin-fixed paraffin-embedded cancer specimens and matched normal tissue were extracted and CGE was performed. An automated computational algorithm for MSI status determination was also developed. Results: Using the fragment analyser, MSI status was found to be 100% concordant with the known MSI status of cell lines and was 86% and 87% concordant with immunohistochemistry (IHC) from patient cancer specimens using traditional assessment and our MSI scoring system, respectively, for MSI determination. The misclassification rate was mainly attributed to IHC, with only one (1.8%) sampling error attributed to CGE testing. CGE was also able to distinguish MSI-L from MSI-H and MSS, which is not possible with IHC. An MSI score based on total allelic variability that can accurately determine MSI status was also successfully developed. A significant reduction in cost compared with traditional fluorescent multiplex PCR and CGE was achieved with this technique. Conclusions: A simple, cost-effective and reliable method of determining MSI status and an MSI scoring system based on an automatic computational algorithm to determine MSI status, as well as degree of allelic instability in colorectal cancer, has been developed using the 5200 Fragment Analyzer System.

Genetic Variants in DNA Repair Pathways as Potential Biomarkers in Predicting Treatment Outcome of Intraperitoneal Chemotherapy in Patients With Colorectal Peritoneal Metastasis: A Systematic Review

Background

The introduction of cytoreductive surgery (CRS) followed by hyperthermic intraperitoneal chemotherapy (HIPEC) with either oxaliplatin or mitomycin C for patients with colorectal peritoneal metastasis (CPM) has resulted in a major increase in overall survival. Nonetheless, despite critical patient selection, the majority of patients will develop recurrent disease within one year following CRS + HIPEC. Therefore, improvement of patient and treatment selection is needed and may be achieved by the incorporation of genetic biomarkers. This systematic review aims to provide an overview of genetic biomarkers in the DNA repair pathway that are potentially predictive for treatment outcome of patients with colorectal peritoneal metastases treated with CRS + HIPEC with oxaliplatin or mitomycin C.

Methods

A systematic review was conducted according to the PRISMA guidelines. Given the limited number of genetic association studies of intraperitoneal mitomycin C and oxaliplatin in patients with CPM, we expanded the review and extrapolated the data from biomarker studies conducted in colorectal cancer patients treated with systemic mitomycin C– and oxaliplatin-based chemotherapy.

Results

In total, 43 papers were included in this review. No study reported potential pharmacogenomic biomarkers in patients with colorectal cancer undergoing mitomycin C–based chemotherapy. For oxaliplatin-based chemotherapy, a total of 26 genetic biomarkers within 14 genes were identified that were significantly associated with treatment outcome. The most promising genetic biomarkers were ERCC1 rs11615, XPC rs1043953, XPD rs13181, XPG rs17655, MNAT rs3783819/rs973063/rs4151330, MMR status, ATM protein expression, HIC1 tandem repeat D17S5, and PIN1 rs2233678.

Conclusion

Several genetic biomarkers have proven predictive value for the treatment outcome of systemically administered oxaliplatin. By extrapolation, these genetic biomarkers may also be predictive for the efficacy of intraperitoneal oxaliplatin. This should be the subject of further investigation.

Finding the hot spot: identifying immune sensitive gastrointestinal tumors

Although researchers have been trying to harness the immune system for over 100 years, the advent of immune checkpoint blockers (ICB) marks an era of significant clinical outcomes in various metastatic solid tumors, characterized by complete and durable responses. ICBs are monoclonal antibodies that target either of a pair of transmembrane molecules in tumors or T-cells involved in immune evasion. Currently 2 ICBs targeting the checkpoint program death 1 (PD-1), nivolumab and pembrolizumab, and one cytotoxic lymphocyte antigen-4 (CTLA-4) inhibitor (ipilimumab) are approved in gastrointestinal malignancies. We review herein the current evidence on predictive biomarkers for ICB response in gastrointestinal tumors. A review of literature based on the National Cancer Institute list of FDA-approved drugs for neoplasms and FDA-approved therapies at the FDA website was performed. An initial literature review was based on the American Association for Clinical Research meeting 2019, the American Society of Clinical Oncology meeting 2019 and the European Society of Medical Oncology 2019 proceedings. A systematic search of PubMed was performed involving MeSH browser terms such as biomarkers, immunotherapy, gastrointestinal diseases and neoplasms. When appropriate, American and British terms were used in the search. The most relevant predictor of response to ICBs is microsatellite instability (MSI) and the data is strongest for colorectal cancer. At least 3 prospective trials show evidence of PD-L1 as a predictive biomarker for ICB response in gastroesophageal malignancies. At least one prospective trial has described tumor mutational burden high (TMB-H), independent of MSI, as predictive of response in anal and biliary tract carcinomas. DNA Polymerase Epsilon (POLE) or delta (POL-D) mutations have been implicated in a subset of MSS colorectal cancer with TMB-H but this biomarker requires prospective validation. There is evolving data based on retrospective observations that gene alterations predicting acquired resistance and hyper-progression. Ongoing clinical research is assessing the role of the human microbiome and RNA-editing complex mutations as predictive biomarkers of response to ICBs. MSI has the strongest predictive power among current biomarkers for ICB response in gastrointestinal cancers. Data continue to accumulate from ongoing clinical trials and new biomarkers are emerging from pre-clinical studies, suggesting that drug combinations targeting pathways complimentary to the PD-1/PD-L1 axis inhibition will define a robust field of clinical research.

Adjuvant Chemotherapy in Microsatellite Instability-High Gastric Cancer

PURPOSE

Microsatellite instability (MSI) status may affect the efficacy of adjuvant chemotherapy in gastric cancer. In this study, the clinical characteristics of MSI-high (MSI-H) gastric cancer and the predictive value of MSI-H for adjuvant chemotherapy in large cohorts of gastric cancer patients were evaluated.

MATERIAL AND METHODS

This study consisted of two cohorts. Cohort 1 included gastric cancer patients who received curative resection with pathologic stage IB-IIIC. Cohort 2 included patients with MSI-H gastric cancer who received curative resection with pathologic stage II/III. MSI was examined using two mononucleotide markers and three dinucleotide markers.

RESULTS

Of 359 patients (cohort 1), 41 patients (11.4%) had MSI-H. MSI-H tumors were more frequently identified in older patients (p < 0.001), other histology than poorly cohesive, signet ring cell type (p=0.005), intestinal type (p=0.028), lower third tumor location (p=0.005), and absent perineural invasion (p=0.027). MSI-H status has a tendency of better disease-free survival (DFS) and overall survival (OS) in multivariable analyses (hazard ratio [HR], 0.4; p=0.059 and HR, 0.4; p=0.063, respectively). In the analysis of 162 MSI-H patients (cohort 2), adjuvant chemotherapy showed a significant benefit with respect to longer DFS and OS (p=0.047 and p=0.043, respectively). In multivariable analysis, adjuvant chemotherapy improved DFS (HR, 0.4; p=0.040).

CONCLUSION

MSI-H gastric cancer had distinct clinicopathologic findings. Even in MSI-H gastric cancer of retrospective cohort, adjuvant chemotherapy could show a survival benefit, which was in contrast to previous prospective studies and should be investigated in a further prospective trial.

Adjuvant chemotherapy in resected colon cancer: When, how and how long?

The benefit of adjuvant chemotherapy has been clearly established in the adjuvant setting for node-positive colon cancer. A number of trials in the adjuvant setting have analyzed the efficacy of multiple-agent combinations, including irinotecan, oxaliplatin, bevacizumab and cetuximab. Only oxaliplatin added to fluorouracil/capecitabine has been shown to be superior beyond a fluropyrimidine alone in the adjuvant setting. As such, standard treatment options include fluorouracil (FU) or capecitabine with or without oxaliplatin. However, oxaliplatin is associated with cumulative dose-dependent neurotoxicity, characterized by distal or perioral paresthesias or dysesthesias; for this reason, in this review we discuss the results of the International Duration Evaluation of Adjuvant Chemotherapy (IDEA) trial. The IDEA trail is the largest prospective clinical trial ever conducted in colorectal cancer, wherein patients were treated with either 3 months or 6 months of adjuvant chemotherapy. In the era of cancer gene expression-based subtyping, the Colorectal Cancer Subtyping Consortium has proposed a four-subgroup molecular classification system for colorectal cancer, consisting of CMS1 (immune), CMS2 (canonical), CMS3 (metabolic) and CMS4 (mesenchymal). In this review, we present and analyze the available data on efficacy and toxicity of the combination regimen approved for treatment of resected colon cancer, and discuss the questions of when, how and how long we need to treat such patients.

Adjuvant chemotherapy in stage II-III operated colon cancer patients from a nontrial cohort in a low colon cancer prevalence country with predominant use of modified CAPOX

BACKGROUND

Data regarding the practice of adjuvant chemotherapy, specifically with modified CAPOX, and survival outcomes in operated colon cancer patients from a nontrial cohort in a lower-middle income and low prevalence nation like India is scarce.

MATERIALS AND METHODS

Patients who underwent upfront curative resection for colon cancer from January 2013 to December 2016 were analyzed for baseline variables and outcomes.

RESULTS

A total of 491 patients underwent curative resection in the predefined time period. The median age of the patients was 53 years (range: 17-87). Patients with Stage I, Stage II, and Stage III disease comprised 7.9%, 44.8%, and 45.4% of the entire cohort, respectively. Patients with Stage I cancer were observed. Adjuvant chemotherapy was planned for 384 patients (78.2%), with the doublet regimens (capecitabine-oxaliplatin, or 5-fluorouracil-oxaliplatin) being used commonly (77.6%). Common toxicities were Hand-foot syndrome (Grade 2/3 - 21.4%) and peripheral neuropathy (Grade 2/3 - 20.1%). About 85% of patients receiving monotherapy (capecitabine or 5 fluorouracil) and 81.2% of patients receiving doublet chemotherapy (mCAPOX or modified FOLFOX-7) completed their planned adjuvant treatment. With a median follow-up of 22 months, estimated 3 years event-free survival was 86%, and overall survival (OS) was 93.6%. Stage, younger age (<50 years), underlying cardiovascular abnormalities, need for dose reductions and noncompletion of planned chemotherapy predicted for inferior estimated 3-year OS on multivariate analysis.

CONCLUSIONS

Adjuvant chemotherapy especially with modified CAPOX appears well tolerated in the Indian population and early survival outcomes appear to be comparable to published literature.

Molecular and Immunohistochemical Markers with Prognostic and Predictive Significance in Liver Metastases from Colorectal Carcinoma

Despite the significant recent achievements in the diagnosis and treatment of colorectal cancer (CRC), the prognosis of these patients has currently plateaued. During the past few years, the opportunity to consider multiple treatment modalities (including surgery and other locoregional treatments, systemic therapy, and targeted therapy) led to the research of novel prognostic and predictive biomarkers in CRC liver metastases (CRCLM) patients. In this review, we seek to describe the current state of knowledge of CRCLM biomarkers and to outline impending clinical perspectives, in particular focusing on the cutting-edge tools available for their characterization.

Expending Role of Microsatellite Instability in Diagnosis and Treatment of Colorectal Cancers

Background

Colorectal carcinomas with high-frequency microsatellite instability (MSI-H) account for 15% of all colorectal cancers, including 12% of sporadic cases and 3% of cancers associated with Lynch syndrome (also known as hereditary nonpolyposis colorectal cancer syndrome, HNPCC). Lynch syndrome is an autosomal dominant hereditary cancer syndrome, caused by germline mutations in mismatch repair genes, including MLH1, MSH2, MSH6 and PMS2.

Methods

Published articles from peer-reviewed journals were obtained from PubMed, Google Scholar and Clinicaltrials.gov. Based on the recent research data, we provide an update on the MSI testing, along with the evolving role of MSI in diagnosis, prognosis and treatment of colorectal cancers.

Results

Studies have led to significant advances in the molecular pathogenesis and clinicopathological characteristics of MSI-H colorectal cancers. Emerging evidence suggests that colorectal cancers with MSI-H show different outcome and treatment response from those with microsatellite stable (MSS) tumors. Therefore, MSI testing is essential not only in the genetic context, but it may also have important prognostic and predictive value of response to chemotherapy and immunotherapy.

Conclusions

Many experts and professional authorities have recommended a universal MSI testing in all individuals newly diagnosed with colorectal cancers.

Molecular Landscape and Treatment Options for Patients with Metastatic Colorectal Cancer

Over the last 20 years, median survival for patients with metastatic colorectal cancer (CRC) has remarkably improved from about 12 to over 30 months, mainly because of the development of new agents and patient selection using predictive biomarkers. However, the identification of the most effective treatment for an individual patient is still a challenge. Molecular profiling of CRC has made great progress, but it is limited by tumor heterogeneity and absence of driver mutation. However, RAS, BRAF, and microsatellite instability are validated biomarker recommended by NCCN and ESMO. In this review, we discuss recent advances and future developments.

Microsatellite Instability was not Associated with Survival in Stage III Colon Cancer Treated with Adjuvant Chemotherapy of Oxaliplatin and Infusional 5-Fluorouracil and Leucovorin (FOLFOX)

BACKGROUND

The impact of microsatellite instability (MSI) on survival in stage III colon cancer treated with adjuvant 5-fluorouracil-oxaliplatin combination (FOLFOX) chemotherapy is not clear. We evaluated the association between MSI and survival in this population.

METHODS

We analyzed 598 patients with curatively resected stage III colon cancer treated with adjuvant FOLFOX chemotherapy. We determined MSI status using polymerase chain reaction amplification; tumors were classified as high MSI (MSI-H, ≥2 unstable markers), low MSI (MSI-L, 1 unstable marker), or microsatellite stable (MSS, no unstable marker).

RESULTS

Of 598 patients, 8.4% showed MSI-H. Tumors classified as MSI-H were more commonly located in the ascending colon (54.0 vs. 27.7%, p < 0.0001) and had poorly differentiated features (32.0 vs. 8.0%, p < 0.0001). After the median follow-up of 52.8 months, 5-year disease-free (DFS) and overall survival (OS) rates were 77.0 and 85.9%, respectively. In univariate analysis, pathologic T4 (pT4) and pathologic N2 (pN2) was associated with reduced DFS (p < 0.0001 and p < 0.0001, respectively) and OS (p = 0.002 and p = 0.001, respectively), whereas MSI status did not affect either DFS (p = 0.114) or OS (p = 0.525). In patients with pN2 tumors; however, MSI-H was associated with better survival compared with MSS/MSI-L; DFS and OS in patients with MSI-H/pN2 were comparable to those in patients with pN1 tumors.

CONCLUSIONS

In patients with stage III colon cancer treated with adjuvant FOLFOX, pT4 and pN2 was associated with reduced survival, but MSI status alone did not affect survival.

Clinical course and outcome of patients with high-level microsatellite instability cancers in a real-life setting: a retrospective analysis

BACKGROUND

The prognostic and predictive significance of the high-level microsatellite instability (MSI-H) phenotype in various malignancies is unclear. We describe the characteristics, clinical course, and outcomes of patients with MSI-H malignancies treated in a real-life hospital setting.

PATIENTS AND METHODS

A retrospective analysis of MSI-H cancer patient files was conducted. We analyzed the genetic data, clinical characteristics, and oncological treatments, including chemotherapy and surgical interventions.

RESULTS

Clinical data of 73 MSI-H cancer patients were available. Mean age at diagnosis of first malignancy was 52.3 years. Eight patients (11%) had more than four malignancies each. Most patients (76%) had colorectal cancer (CRC). Seventeen patients (23%) had only extracolonic malignancies. Eighteen women (36%) had gynecological malignancy. Nine women (18%) had breast cancer. Mean follow-up was 8.5 years. Five-year overall survival and disease-free survival of all MSI-H cancer patients from first malignancy were 86% and 74.6%, respectively. Five-year overall survival rates of stage 2, 3, and 4 MSI-H CRC patients were 89.5%, 58.4%, and 22.9%, respectively.

CONCLUSION

Although the overall prognosis of MSI-H cancer patients is favorable, this advantage may not be maintained in advanced MSI-H CRC patients.

The evolving role of microsatellite instability in colorectal cancer: A review

Microsatellite instability (MSI) is a molecular marker of a deficient mismatch repair (MMR) system and occurs in approximately 15% of colorectal cancers (CRCs), more frequently in early than late-stage of disease. While in sporadic cases (about two-thirds of MSI-H CRCs) MMR deficiency is caused by an epigenetic inactivation of MLH1 gene, the remainder are associated with Lynch syndrome, that is linked to a germ-line mutation of one of the MMR genes (MLH1, MSH2, MSH6, PMS2). MSI-H colorectal cancers have distinct clinical and pathological features such as proximal location, early-stage (predominantly stage II), poor differentiation, mucinous histology and association with BRAF mutations. In early-stage CRC, MSI can select a group of tumors with a better prognosis, while in metastatic disease it seems to confer a negative prognosis. Although with conflicting results, a large amount of preclinical and clinical evidence suggests a possible resistance to 5-FU in these tumors. The higher mutational load in MSI-H CRC can elicit an endogenous immune anti-tumor response, counterbalanced by the expression of immune inhibitory signals, such as PD-1 or PD-L1, that resist tumor elimination. Based on these considerations, MSI-H CRCs seem to be particularly responsive to immunotherapy, such as anti-PD-1, opening a new era in the treatment landscape for patients with metastatic CRC.

Microsatellite instability testing and its role in the management of colorectal cancer

Opinion statement: TNM stage remains the key determinant of patient prognosis after surgical resection of colorectal cancer (CRC), and informs treatment decisions. However, there is considerable stage-independent variability in clinical outcome that is likely due to molecular heterogeneity. This variability underscores the need for robust prognostic and predictive biomarkers to guide therapeutic decision-making including the use of adjuvant chemotherapy. Although the majority of CRCs develop via a chromosomal instability pathway, approximately 12-15 % have deficient DNA mismatch repair (dMMR) which is characterized in the tumor by microsatellite instability (MSI). Tumors with the dMMR/MSI develop from a germline mutation in an MMR gene (MLH1, MSH2, MSH6, PMS2), i.e., Lynch syndrome, or more commonly from epigenetic inactivation of MLH1 MMR gene. CRCs with dMMR/MSI status have a distinct phenotype that includes predilection for the proximal colon, poor differentiation, and abundant tumor-infiltrating lymphocytes. Consistent data indicate that these tumors have a better stage-adjusted survival compared to proficient MMR or microsatellite stable (MSS) tumors and may respond differently to 5-fluorouracil-based adjuvant chemotherapy. To increase the identification of dMMR/MSI patients in clinical practice that includes those with Lynch syndrome, it is recommended that all resected CRCs to be analyzed for MMR status. Available data indicate that patients with stage II dMMR CRCs have an excellent prognosis and do not benefit from 5-fluorouracil (FU)-based adjuvant chemotherapy which supports their recommended management by surgery alone. In contrast, the benefit of standard adjuvant chemotherapy with the FOLFOX regiment in stage III dMMR CRC patients awaits further study and therefore, all patients should be treated with standard adjuvant FOLFOX.

Prognostic factors in sporadic colon cancer with high-level microsatellite instability

BACKGROUND

The microsatellite instability-high (MSI-H) phenotype of colon cancer has a good prognosis and limited response to chemotherapy. We aimed to investigate prognostic factors and oncologic outcomes in patients with MSI-H sporadic colon cancer.

METHODS

A total of 329 patients with MSI-H sporadic colon cancer who underwent radical surgery from January 2004 to December 2012 at a single institution were included. We analyzed prognostic factors and oncologic outcomes according to chemotherapy in these patients compared with patients with MSI-low/microsatellite stable colon cancer.

RESULTS

Among the 329 patients, 174 were male and 155 were female. The median age was 59 years. The population consisted of 220 patients with stage II, 97 with stage III, and 12 with stage IV disease. Old age and advanced stage were independent poor prognostic factors of overall survival (OS; P = .014 and P = .040, respectively) and advanced stage and presence of perineural invasion were independent poor prognostic factors of disease-free survival (DFS; P = .004 and P = .001, respectively). In addition, a greater number of poor prognostic factors were associated with worse survival (P < .001). Patients with stage II disease showed no differences in OS and DFS according to receiving or not receiving chemotherapy (P = .140 and P = .694, respectively).

CONCLUSION

Old age, advanced stage, and presence of perineural invasion were independent and poor prognostic factors in patients with MSI-H sporadic colon cancer. Survival rates of MSI-H colon cancer patients with stage II disease were not improved by adjuvant chemotherapy.

Implications of mismatch repair-deficient status on management of early stage colorectal cancer

For primary colorectal cancers (CRCs), tumor stage has been the best predictor of survival after resection and the key determinant of patient management. However, considerable stage-independent variability in clinical outcome is observed that is likely due to molecular heterogeneity. This is particularly important in early stage CRCs where patients can be cured by surgery alone and only a proportion derives benefit from adjuvant chemotherapy. Thus, the identification of molecular prognostic markers to supplement conventional pathologic staging systems has the potential to guide patient management and influence outcomes. CRC is a heterogeneous disease with molecular phenotypes reflecting distinct forms of genetic instability. The chromosomal instability pathway (CIN) is the most common phenotype, accounting for 85% of all sporadic CRCs. Alternatively, the microsatellite instability (MSI) phenotype represents ~15% of all CRCs and is caused by deficient DNA mismatch repair (MMR) as a consequence of germline mutations in MMR genes or, more commonly, epigenetic silencing of the MLH1 gene with frequent mutations in the BRAF oncogene. MSI tumors have distinct phenotypic features and are consistently associated with a better stage-adjusted prognosis compared with microsatellite stable (MSS) tumors. Among non-metastatic CRCs, the difference in prognosis between MSI and MSS tumors is larger for stage II than stage III patients. On the other hand, the predictive impact of MMR status for adjuvant chemotherapy remains a contentious issue in that most studies demonstrate a lack of benefit for 5-fluorouracil (5-FU)-based adjuvant chemotherapy in stage II MSI-H CRCs, whereas it remains unclear in MSI-H stage III tumors. Here, we describe the molecular aspects of the MMR system and discuss the implications of MMR-deficient/MSI-H status in the clinical management of patients with early stage CRC.

Chemotherapy for Stage II Colon Cancer

The adjuvant treatment of patients with stage II colon cancer is an area of controversy in medical oncology. Adjuvant chemotherapy aims to eradicate micrometastatic disease present at the time of surgery, preventing the development of distant metastatic disease and thereby curing those patients of their cancer. National and international guidelines for the adjuvant treatment of stage II colon cancer recommend a range of treatment options from observation to chemotherapy with single-agent or combination regimens, depending on the presence or absence of high-risk features (poorly differentiated histology, presence of lymphovascular invasion, presence of perineural invasion, report of < 12 lymph nodes, bowel obstruction, localized perforation, or positive margins). In the one prospective study designed to address the role of adjuvant chemotherapy in stage II colon cancer, a small but statistically significant benefit in overall survival was seen for those patients who received adjuvant chemotherapy; however, multiple meta-analyses and retrospective subgroup analyses have called these findings into question. Though there may be a role for adjuvant chemotherapy in the treatment of patients with stage II colon cancer, its incremental benefit is small, at best, and comes with the risks of real and rarely fatal complications of chemotherapy.

The 1,2-Diaminocyclohexane Carrier Ligand in Oxaliplatin Induces p53-Dependent Transcriptional Repression of Factors Involved in Thymidylate Biosynthesis

Platinum-based chemotherapeutic drugs are widely used as components of combination chemotherapy in the treatment of cancer. One such drug, oxaliplatin, exerts a synergistic effect against advanced colorectal cancer in combination with 5-fluorouracil (5-FU) and leucovorin. In the p53-proficient colorectal cancer cell line HCT116, oxaliplatin represses the expression of deoxyuridine triphosphatase (dUTPase), a ubiquitous pyrophosphatase that catalyzes the hydrolysis of dUTP to dUMP and inhibits dUTP-mediated cytotoxicity. However, the underlying mechanism of this activity has not been completely elucidated, and it remains unclear whether factors other than downregulation of dUTPase contribute to the synergistic effect of 5-FU and oxaliplatin. In this study, we found that oxaliplatin and dachplatin, platinum-based drugs containing the 1,2-diaminocyclohexane (DACH) carrier ligand, repressed the expression of nuclear isoform of dUTPase (DUT-N), whereas cisplatin and carboplatin did not. Oxaliplatin induced early p53 accumulation, upregulation of primary miR-34a transcript expression, and subsequent downregulation of E2F3 and E2F1. Nutlin-3a, which activates p53 nongenotoxically, had similar effects. Introduction of miR-34a mimic also repressed E2F1 and DUT-N expression, indicating that this miRNA plays a causative role. In addition to DUT-N, oxaliplatin repressed, in a p53-dependent manner, the expression of genes encoding enzymes involved in thymidylate biosynthesis. Consequently, oxaliplatin significantly decreased the level of dTTP in the dNTP pool in a p53-dependent manner. These data indicate that the DACH carrier ligand in oxaliplatin triggers signaling via the p53-miR-34a-E2F axis, leading to transcriptional regulation that ultimately results in accumulation of dUTP and reduced dTTP biosynthesis, potentially enhancing 5-FU cytotoxicity.

Deficient mismatch repair: Read all about it (Review)

Defects in the DNA mismatch repair (MMR) proteins, result in a phenotype called microsatellite instability (MSI), occurring in up to 15% of sporadic colorectal cancers. Approximately one quarter of colon cancers with deficient MMR (dMMR) develop as a result of an inherited predisposition syndrome, Lynch syndrome (formerly known as HNPCC). It is essential to identify patients who potentially have Lynch syndrome, as not only they, but also family members, may require screening and monitoring. Diagnostic criteria have been developed, based primarily on Western populations, and several methodologies are available to identify dMMR tumours, including immunohistochemistry and microsatellite testing. These criteria have provided evidence supporting the introduction of reflex testing. Yet, it is becoming increasingly clear that tests have a limited sensitivity and specificity and may yet be superseded by next generation sequencing. In this review, the limitations of diagnostic criteria are discussed, and current and emerging screening technologies explained. There is now useful evidence supporting the prognostic and predictive value of dMMR status in colorectal tumours, but much less is known about their value in extracolonic tumours, that may also feature in Lynch syndrome. This review assesses current literature relating to dMMR in endometrial, ovarian, gastric and melanoma cancers, which it would seem, may benefit from large-scale clinical trials in order to further close the gap in knowledge between colorectal and extracolonic tumours.

Genetics, biomarkers, hereditary cancer syndrome diagnosis, heterogeneity and treatment: a review

OPINION STATEMENT

Molecular genetic pathways that drive the phenotypic and genotypic heterogeneity of hereditary colorectal cancer also can affect response to chemotherapy and chemoprevention. These mutations also can alter patients' response to therapy. Environmental differences can affect this highly complex conundrum. We will use Lynch syndrome as a model to explore this issue. However, to begin with, after more than a century of documentation, we must ask what is meant by the eponym "Lynch syndrome". Germline mutations may act as drivers of chemoprevention and chemotherapy and therein may act positively or conversely they may have a negative effect in terms of inhibiting the inactivation of cancer-causing germline mutations. A relatively new field of hereditary cancer therapeutics has significantly impacted cancer care, from the standpoint of the sensitivity or resistance to a particular form of chemotherapy and/or chemoprevention. The question for the diagnostician and therapist must always concern what is the best possible management approach for the patient, particularly when he or she harbors a cancer-causing germline mutation, which, in this case, causes Lynch syndrome. Continued molecular genetic research might yield a more tailored effective treatment for Lynch syndrome. The ultimate goal of such hereditary oncologic research is to better understand the mutation's therapeutic task, namely, its potential to benefit the patient in terms of its treatment goal, thereby fulfilling the essence of personalized medicine. However, this goal may be exceedingly complicated. For example, in the natural clinical and molecular genetic history of hereditary forms of cancer, there will be a predominance of early-onset cancers of multiple anatomic sites. In our Lynch syndrome model, these will be most commonly colorectal, endometrial, and ovarian cancer. Attention must initially be focused upon cancer's early age of onset coupled with the tendency to multiple primary cancers so that, in the case of CRC, colonoscopic screening must be initiated by age 20-25 years and repeated every other year until age 40 years and then annually thereafter. However, screening will be of limited efficacy in the gynecologic cancers (endometrial and ovarian) so that once the family is completed, particularly by age 35-40 years, careful attention must be given to the option of prophylactic hysterectomy and bilateral salpingo-oophorectomy. Given issues of tumor heterogeneity, selected Lynch syndrome families may show an excess of urologic cancers or cancers of the small bowel, and highly targeted screening should be given serious consideration for these as well as cancers of other anatomic sites in such high-risk, cancer-prone patients.

Clinicopathologic impacts of poorly differentiated cluster-based grading system in colorectal carcinoma

Differentiation-based histologic grading of colorectal carcinoma (CRC) is widely used, but its clinical impact is limited by insufficient prognostic value, interobserver disagreement, and the difficulty of its application to CRC with specific histologic types such as mucinous and medullary carcinoma. A recently proposed novel grading system based on quantifying poorly differentiated clusters (PDCs) claims to have the advantages of reproducibility and improved prognostic value, and might apply to heterogeneous CRC. We aimed to validate the clinicopathologic significance of the PDCs-based grading system and to determine the relationship between this grading system and microsatellite instability (MSI). Two hundred and one patients who had undergone radical surgery were reviewed. Based on the number of PDCs, 85, 58, and 58 tumors were classified as grade (G) 1 (42.3%), G2 (28.9%), and G3 (28.9%), respectively. PDCs-based grade was significantly associated with T, N, and M stages; lymphovascular invasion; conventional histologic grade; and frequent tumor budding (all P <0.001). In multivariate analysis, PDCs-based grade was found to be an independent prognostic factor for disease-free survival (P = 0.022; hazard ratio, 3.709 [G2], 7.461 [G3]). G3 CRC significantly correlated with high MSI (MSI-H) compared to G1 and G2 (P = 0.002; odds ratio, 5.750). In conclusion, this novel grading would provide valuable prognostic information to a greater number of patients and would require continued verification. PDCs-based grading is feasible for CRCs with heterogeneous morphology, and we propose that the association between G3 and MSI-H be further evaluated in different histological subtypes of CRC.

Pharmacogenetics research on chemotherapy resistance in colorectal cancer over the last 20 years

During the past two decades the first sequencing of the human genome was performed showing its high degree of inter-individual differentiation, as a result of large international research projects (Human Genome Project, the 1000 Genomes Project International HapMap Project, and Programs for Genomic Applications NHLBI-PGA). This period was also a time of intensive development of molecular biology techniques and enormous knowledge growth in the biology of cancer. For clinical use in the treatment of patients with colorectal cancer (CRC), in addition to fluoropyrimidines, another two new cytostatic drugs were allowed: irinotecan and oxaliplatin. Intensive research into new treatment regimens and a new generation of drugs used in targeted therapy has also been conducted. The last 20 years was a time of numerous in vitro and in vivo studies on the molecular basis of drug resistance. One of the most important factors limiting the effectiveness of chemotherapy is the primary and secondary resistance of cancer cells. Understanding the genetic factors and mechanisms that contribute to the lack of or low sensitivity of tumour tissue to cytostatics is a key element in the currently developing trend of personalized medicine. Scientists hope to increase the percentage of positive treatment response in CRC patients due to practical applications of pharmacogenetics/pharmacogenomics. Over the past 20 years the clinical usability of different predictive markers has been tested among which only a few have been confirmed to have high application potential. This review is a synthetic presentation of drug resistance in the context of CRC patient chemotherapy. The multifactorial nature and volume of the issues involved do not allow the author to present a comprehensive study on this subject in one review.

Should mismatch repair status be determined in all stage II and III colon cancer patients?

SUMMARY 

Microsatellite instability constitutes an important oncogenic molecular pathway in colon cancer (12–15%). Microsatellite instability is a molecular marker of deficient DNA mismatch repair (MMR), which occurs from somatic hypermethylation of the MLH1 promoter or less frequently as a result of germline mutations in MMR genes. The excellent prognosis of patients with stage II deficient MMR colon cancer today, makes this information mandatory in order to decide or not on adjuvant chemotherapy. MMR deficiency may also predict tumor chemoresistance to 5-fluorouracil adjuvant treatment. However, when looking at very recent data on 5-fluorouracil plus oxaliplatin-based adjuvant regimens, it seems that the benefit of this adjuvant therapy is similar between deficient and proficient MMR patients.

Prognostic Impact of Deficient DNA Mismatch Repair and Mutations in KRAS, and BRAFV600E in Patients with Lymph Node-Positive Colon Cancer

While tumor stage remains the key determinant of colorectal cancer (CRC) prognosis and treatment, there is considerable stage-independent variability in clinical outcome. Molecular markers hold promise for explaining variations in clinical behavior, and may identify patient subsets with differential efficacy and survival after adjuvant chemotherapy which is standard of care for patients with lymph node-positive, i.e., stage III, colon cancer. An increased understanding of the molecular evolution and progression of CRC has identified two major pathways of tumorigenesis that are characterized by chromosomal instability or microsatellite instability (MSI). MSI is a consequence of deficient DNA mismatch repair (MMR) that is generally due to epigenetic inactivation of MLH1 in tumors that often carry mutations in oncogenic BRAF^V600E . Activating BRAF^V600E and KRAS mutations are mutually exclusive and in this article, we review the current status of these mutations and MMR status as prognostic biomarkers in stage III colon cancers.

Molecular and prognostic heterogeneity of microsatellite-unstable colorectal cancer

Colorectal cancers (CRCs) with a high level of microsatellite instability (MSI-H) are clinicopathologically distinct tumors characterized by predominance in females, proximal colonic localization, poor differentiation, mucinous histology, tumor-infiltrating lymphocytes, a Crohn's-like lymphoid reaction and a favorable prognosis. In terms of their molecular features, MSI-H CRCs are heterogeneous tumors associated with various genetic and epigenetic alterations, including DNA mismatch repair deficiency, target microsatellite mutations, BRAF mutations, a CpG island methylator phenotype-high (CIMP-H) status, and a low level of genomic hypomethylation. The molecular heterogeneity of MSI-H CRCs also depends on ethnic differences; for example, in Eastern Asian countries, relatively low frequencies of CIMP-H and BRAF mutations have been observed in MSI-H CRCs compared to Western countries. Although the prognostic features of MSI-H CRCs include a favorable survival of patients and low benefit of adjuvant chemotherapy, there may be prognostic differences based on the molecular heterogeneity of MSI-H CRCs. Here, we have reviewed and discussed the molecular and prognostic features of MSI-H CRCs, as well as several putative prognostic or predictive molecular markers, including HSP110 expression, beta2-microglobulin mutations, myosin 1a expression, CDX2/CK20 expression, SMAD4 expression, CIMP status and LINE-1 methylation levels.

Chemotherapy of MMR-deficient colorectal cancer

Colorectal cancer (CRC) continues to rank as the third most common cancer in Western society and the second leading cause of cancer death in North America. There are at least three distinct, and relatively discreet, molecular pathways associated with this disease: chromosomal instability (CIN), microsatellite instability (MSI) and the cytosine polyguanine island methylator phenotype. Defects in the DNA mismatch repair system (MMR) account for the MSI phenotype and genotype of about 15 % of CRC. Although high frequency MSI tumors have better stage independent prognosis compared to those with CIN, MMR deficient CRC appears to be resistant to fluorouracil based treatment, but sensitive to other therapeutic regimens. This review summarises current literature on differential chemosensitivity of MMR-deficient CRC.

Is microsatellite instability really a good prognostic factor of colorectal cancer?

PURPOSE

The aim of this study was to investigate the clinicopathologic features of and the prognosis for colorectal cancers (CRCs) with microsatellite instabilities (MSIs).

METHODS

Between 2006 and 2009, genotyping was performed on 245 patients with stage II/III CRCs to establish the MSI status. The clinicopathologic differences and the prognostic value of MSI were analyzed. The median follow-up period was 38 months (range, 7-68 months).

RESULTS

Of the total 245 patients, 20 (8.2%) had MSI-high (H) and 225 (91.8%) had MSI-low (L) or stable (S) CRCs. Adjuvant chemotherapies were performed on 101 stage II (87.8%) and 107 stage III patients (82.3%). Patients with MSI-H CRCs more frequently had a family history of colon cancer (10% vs. 2.7%, P = 0.003), more frequently had a cancer located at the proximal colon (90.0% vs. 19.1%, P < 0.0001), and more often showed a mucinous phenotype or poor differentiation (35.0% vs. 7.1%, P = 0.001). Despite less frequent lymph node metastasis (25% vs. 55.6%, P = 0.01), the number of retrieved lymph nodes was higher (26.3 ± 13.1 vs. 20.7 ± 1.2, P = 0.04) in the MSI-H group. The overall survival and the disease-free survival (DFS) did not differ with respect to MSI status. However, in the stage II subgroup, the DFS for patients with MSI-H CRCs was significantly worse (72.2% vs. 90.7%, P = 0.03). The multivariate analysis performed on this subgroup revealed that MSI-H was an independent poor prognostic factor (adjusted hazard ratio, 4.0; 95% confidence interval, 1.0-15.6, P = 0.046).

CONCLUSION

MSI-H CRCs had distinct clinicopathologic features, and MSI-H was an independent poor prognostic factor in stage II CRCs. Considering the majority of stage II patients were administrated adjuvant chemotherapy, the efficacy of adjuvant chemotherapy for treating MSI CRCs might be different from that for treating MSI-L/S tumors.

Does the prognosis of colorectal mucinous carcinoma depend upon the primary tumour site? Results from two independent databases

AIMS

Mucinous adenocarcinoma (MUC) is a commonly studied histological subtype of colorectal adenocarcinoma. However, the prognostic value of MUC remains unclear, particularly in patients stratified by the primary tumour site. We aimed to analyse the prognostic value of MUC in colorectal cancer.

METHODS AND RESULTS

We utilized two independent data sets in this study: (i) the National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) data set, and (ii) the data set from a single Chinese institution (the Department of Surgical Oncology at the First Hospital of China Medical University). Patient survival was analysed using Kaplan-Meier survival curves, and comparisons were performed using the log-rank test. MUC occurred more frequently in patients who exhibited higher pT category, higher pN category, higher TNM stage, left-sided colon cancer and higher histological grade. Based on the SEER data set, MUC was an independent negative survival indicator in rectal cancer (HR 1.125, 1.056-1.199; P < 0.001). While there was no significant association in left-sided colon cancer (P > 1.000), MUC was an independent protective survival indicator in right-sided colon cancer (HR 0.925, 0.888-0.962; P < 0.001).

CONCLUSIONS

MUC was associated independently with poorer outcome for rectal cancer and was an independent protective survival indicator in right-sided colon cancer. MUC exhibited a different outcome depending on tumour position for patients with colorectal cancer.

Microsatellite instability status affects gene expression profiles in early onset colorectal cancer patients

BACKGROUND

The association between microsatellite instability (MSI) status and gene expression profiles in the early onset sporadic colorectal cancer (CRC) has not been clearly established. The aim of this study was to identify the altered gene expression patterns depending on the MSI status of early onset CRC and determine specific biomarkers that could provide novel therapeutic molecular targets in the Turkish population.

MATERIALS AND METHODS

MSI markers (BAT25, BAT26, D2S123, D5S346, and D17S250) were investigated in tumors from 36 early onset sporadic CRC patients in whom gene expression profiles were analyzed previously. The relationship between the gene expression profiles depending on MSI status was evaluated.

RESULTS

A total of 15 tumors (16.66%) were identified as having MSI and 21 tumors (58.33%) were identified as having microsatellite stability (MSS). CK20 and MAP3K8 upregulation, observed in MSS tumors, was significantly associated with lymph node metastasis, recurrence, and/or distant metastasis and a short median survival (P < 0.05). REG1A upregulation is also correlated with recurrence and/or distant metastasis and a short median survival in patients with MSI tumors (P < 0.05).

CONCLUSIONS

High expression levels of CK20 and MAP3K8 in MSS tumors and REG1A in MSI tumors correlated with a poor prognosis in CRC patients. Further studies and validations are required; these genes may provide novel therapeutic molecular targets for the development of anticancer drugs related to MSI status for early onset CRC treatment.

Individualized therapy for metastatic colorectal cancer

Systemic therapeutic efficacy is central to determining the outcome of patients with metastatic colorectal cancer (CRC). In these patients, there is a critical need for predictive biomarkers to optimize efficacy whilst minimizing toxicity. The integration of a new generation of molecularly targeted drugs into the treatment of CRC, coupled with the development of sophisticated technologies for individual tumours as well as patient molecular profiling, underlines the potential for personalized medicine. In this review, we focus on the latest progress made within the genomic and proteomic fields, concerning predictive biomarkers for individualized therapy in metastatic CRC.

Oncologic management of hereditary colorectal cancer

Colorectal cancer (CRC) is the second most common cancer in females and the third most common cancer diagnosed in males. Familial CRC comprises ~20 to 30% of all CRC cases. Lynch syndrome (LS), previously called hereditary nonpolyposis CRC (HNPCC), is the most common of the hereditary CRC syndromes. In this review, the oncological management of hereditary colorectal cancer from the medical oncologist perspective is discussed with special emphasis on Lynch syndrome. Lynch syndrome is characterized by the presence of germline mutations in the mismatch repair genes (MMR)-MSH2, MLH1, MSH6, and PMS2. The available data regarding the prognostic role of mismatch repair genes (MMR), the predictive role of MMR genes, and the implications of that in the management of patients with deficient MMR genes (dMMR/MSI-H) tumors including Lynch syndrome patients are also discussed.

Role of microsatellite instability in the management of colorectal cancers

Microsatellite instability is the consequence of a deficient mismatch repair system. It has a key role in the diagnostic strategy of Lynch syndrome, where tumours are all characterized by the presence of this phenotype. Microsatellite instability is therefore essential in the selection of colorectal cancer patients in whom a germline analysis of Mismatch Repair genes is possibly indicated. Moreover, microsatellite instability tumours are associated with a good prognosis and a resistance to fluorouracil-based adjuvant chemotherapy, which has a clinical application mainly in stage II colon cancer patients in whom adjuvant chemotherapy has a less beneficial effect than in stage III and outcome in presence of microsatellite instability is excellent. Recent data suggest that impact of microsatellite instability on benefit to fluorouracil-based adjuvant chemotherapy is dependent of the molecular mechanism involved in this genetic instability since an improved survival has been reported with adjuvant fluorouracil in microsatellite instability colorectal cancers of germline origin but not in sporadic cases. Predictive value of microsatellite instability on response to fluorouracil/oxaliplatin adjuvant chemotherapy has been less evaluated but recent studies suggest that the favorable outcome of Microsatellite instability tumours is maintained in patients receiving FOLFOX.

Prognostic implication of mucinous histology in colorectal cancer patients treated with adjuvant FOLFOX chemotherapy

BACKGROUND

There have been controversies in prognostic impact of mucinous histology on colorectal cancer, and its implication in patients treated with adjuvant 5-fluorouracil, leucovorin, and oxaliplatin (FOLFOX) is unclear.

METHODS

Stage II and III colorectal cancer patients who underwent curative resection followed by adjuvant FOLFOX were included. Patients were grouped according to the mucinous content: >50%, mucinous adenocarcinoma (MAC); <50%, adenocarcinoma with intermediated mucinous component (AIM); and without any mucinous component, non-MAC (NMA). Clinicopathological features and disease-free survival (DFS) were compared.

RESULTS

Among a total of 521 patients, 27 patients (5.2%) had MAC, 41 patients (7.9%) had AIM, and 453 patients (86.9%) had NMA. Mucinous adenocarcinoma and AIM had higher frequency of proximal location and microsatellite instability, but lower frequency of angiolymphatic invasion. Disease-free survival was significantly worse in the MAC compared with NMA (3-year DFS 57% and 86%, respectively; P<0.001) and AIM (3-year DFS 87%, P=0.01 vs MAC). Multivariate analysis revealed MAC as an independent negative prognostic factor of DFS (adjusted hazard ratio 7.96, 95% confidence interval 3.76-16.8).

CONCLUSION

Adenocarcinoma with intermediated mucinous component and MAC have distinct clinicopathological features compared with NMA. Mucinous adenocarcinoma has an adverse prognostic impact on stage II or III colorectal cancer treated with adjuvant FOLFOX.

Comparison of NCCN, NICE and Chinese Ministry of Health guidelines for diagnosis and treatment of colorectal cancer

Colorectal cancer (CRC) is one of the most common gastrointestinal malignancies in China. With the increasing in the incidence of CRC in recent years, standardization of the diagnosis and treatment of CRC has attracted more and more attention from clinicians. Over the past years, although clinicians in China mainly refer to the NCCN guideline, the NICE guideline also attracts wide attention. In addition, the Chinese Ministry of Health guideline for the diagnosis and treatment of CRC was issued on October, 2010. In this paper, we will compare and interpret the above three guidelines.

Methylation and microsatellite status and recurrence following adjuvant FOLFOX in colorectal cancer

The prognostic impact of CpG island methylator phenotype (CIMP) and microsatellite instability (MSI) on the treatment outcome of colon cancer patients receiving adjuvant 5-fluorouracil/leucovorin/oxaliplatin (FOLFOX) is unclear. We investigated CIMP and MSI status in colorectal cancer patients treated with adjuvant FOLFOX. Stages II and III sporadic colorectal cancer patients who underwent curative resection followed by adjuvant FOLFOX were included. Eight CpG island loci (CACNA1G, CRABP1, IGF2, MLH1, NEUROG1, CDKN2A (p16), RUNX3 and SOCS1) and five microsatellite markers were examined. Disease-free survival (DFS) was analyzed according to CIMP and MSI status. A total of 322 patients were included: male/female 192/130, median age 61 years (range 30-78), proximal/distal location 118/204 and Stages II/III 43/279. CIMP status was high in 25 patients (7.8%) and 21 patients (6.5%) had MSI-high tumor. CIMP/MSI status was not significantly associated with DFS: 3-year DFS 100% in CIMP(-)/MSI(+), 84% in CIMP(-)/MSI(-), 82% in CIMP(+)/MSI(-) and 75% in CIMP(+)/MSI(+) (p = 0.33). Results of exploratory analysis showed that concurrent methylation at NEUROG1 and CDKN2A (p16) was associated with shorter DFS: 3-year DFS 69% in NEUROG1(+)/CDKN2A (p16)(+) versus 87% in NEUROG1(-)/CDKN2A (p16)(-) (p = 0.006). In conclusion, concurrent methylation of NEUROG1 and CDKN2A (p16) is associated with recurrence following adjuvant FOLFOX in Stages II/III colorectal cancer.

Therapeutic implications of DNA mismatch repair in adjuvant colorectal cancer chemotherapy

SUMMARY Microsatellite instability (MSI) is a molecular marker of defective DNA mismatch repair (MMR) and constitutes an important oncogenic molecular pathway in colorectal cancer that is present in approximately 12–15% of all colorectal malignant tumors. Defective MMR status in colorectal cancer occurs as a result of germline mutations in MMR genes (less than one third of cases) or, more commonly, from somatic hypermethylation of the MLH1 promoter (more than two thirds). MMR deficiency accelerates colorectal oncogenesis by accumulation of secondary mutations in specific target genes. Patients with defective MMR tumors have distinct clinicopathologic characteristics and have been associated with a better stage-adjusted prognosis than patients with proficient MMR tumors. MMR deficiency may predict tumor chemoresistance to adjuvant 5-fluorouracil treatment. Preliminary clinical data suggested that adding oxaliplatin to 5-fluorouracil could restore the benefit of adjuvant chemotherapy in MSI patients. Further studies are needed to clarify the differential chemosensitivity of MSI patients depending on the mechanism of MMR deficiency and the adjuvant chemotherapeutic regimen used.

A multi-center phase Ib study of oxaliplatin (NSC#266046) in combination with fluorouracil and leucovorin in pediatric patients with advanced solid tumors

BACKGROUND

Platinum agents have been used for a variety of cancers, including pivotal use in pediatric tumors for many years. Oxaliplatin, a third generation platinum, has a different side effect profile and may provide improved activity in pediatric cancers.

PROCEDURE

Patients 21 years or younger with progressive or refractory malignant solid tumors, including tumors of the central nervous system were enrolled on this multi-center open label, non-randomized Phase 1 dose escalation study. The study used a standard 3 + 3 dose escalation design with 2 dose levels (85 and 100 mg/m(2) ) with an expansion cohort of 15 additional patients at the recommended dose. Patients received oxaliplatin at the assigned dose level and 5-fluorouracil (5-FU) bolus 400 mg/m(2) followed by a 46-hour 5-FU infusion of 2,400 mg/m(2) every 14 days. The leucovorin dose was fixed at 400 mg/m(2) for all cohorts.

RESULTS

Thirty-one evaluable patients were enrolled, 8 at 85 mg/m(2) and 23 at 100 mg/m(2) for a total of 121 courses. The median age was 12 years (range 2-19 years). The main toxicities were hematologic, primarily neutrophils and platelets. The most common non-hematologic toxicities were gastrointestinal. Stable disease was noted in 11 patients (54% of evaluable patients) and 1 confirmed partial response in a patient with osteosarcoma.

CONCLUSIONS

The maximum planned dose of oxaliplatin at 100 mg/m(2) per dose in combination with 5-FU and leucovorin was safe and well tolerated and in this patient population. This combination demonstrated modest activity in patients with refractory or relapsed solid tumor and warrants further study. Pediatr Blood Cancer 2013;60:230-236. © 2012 Wiley Periodicals, Inc.

Establishment, characterization and chemosensitivity of three mismatch repair deficient cell lines from sporadic and inherited colorectal carcinomas

BACKGROUND

Colorectal cancer (CRC) represents a morphologic and molecular heterogenic disease. This heterogeneity substantially impairs drug effectiveness and prognosis. The subtype of mismatch repair deficient (MMR-D) CRCs, accounting for about 15% of all cases, shows particular differential responses up to resistance towards currently approved cytostatic drugs. Pre-clinical in vitro models representing molecular features of MMR-D tumors are thus mandatory for identifying biomarkers that finally help to predict responses towards new cytostatic drugs. Here, we describe the successful establishment and characterization of three patient-derived MMR-D cell lines (HROC24, HROC87, and HROC113) along with their corresponding xenografts.

METHODOLOGY

MMR-D cell lines (HROC24, HROC87, and HROC113) were established from a total of ten clinicopathological well-defined MMR-D cases (120 CRC cases in total). Cells were comprehensively characterized by phenotype, morphology, growth kinetics, invasiveness, and molecular profile. Additionally, response to clinically relevant chemotherapeutics was examined in vitro and in vivo.

PRINCIPAL FINDINGS

Two MMR-D lines showing CIMP-H derived from sporadic CRC (HROC24: K-ras(wt), B-raf(mut), HROC87: K-ras(wt), B-raf(mut)), whereas the HROC113 cell line (K-ras(mut), B-raf(wt)) was HNPCC-associated. A diploid DNA-status could be verified by flow cytometry and SNP Array analysis. All cell lines were characterized as epithelial (EpCAM(+)) tumor cells, showing surface tumor marker expression (CEACAM(+)). MHC-class II was inducible by Interferon-γ stimulation. Growth kinetics as well as invasive potential was quite heterogeneous between individual lines. Besides, MMR-D cell lines exhibited distinct responsiveness towards chemotherapeutics, even when comparing in vitro and in vivo sensitivity.

CONCLUSIONS

These newly established and well-characterized, low-passage MMR-D cell lines provide a useful tool for future investigations on the biological characteristics of MMR-D CRCs, both of sporadic and hereditary origin. Additionally, matched patient-derived immune cells allow for comparative genetic studies.

How many diseases are colorectal cancer?

The development of personalised therapy and mechanism-targeted agents in oncology mandates the identification of the patient populations most likely to benefit from therapy. This paper discusses the increasing evidence as to the heterogeneity of the group of diseases called colorectal cancer. Differences in the aetiology and epidemiology of proximal and distal cancers are reflected in different clinical behaviour, histopathology, and molecular characteristics of these tumours. This may impact response both to standard cytotoxic therapies and mechanism-targeted agents. This disease heterogeneity leads to challenges in the design of clinical trials to assess novel therapies in the treatment of "colorectal cancer."

The proportion of tumor-stroma as a strong prognosticator for stage II and III colon cancer patients: validation in the VICTOR trial

BACKGROUND

The intra-tumor stroma percentage in colon cancer (CC) patients has previously been reported by our group as a strong independent prognostic parameter. Patients with a high stroma percentage within the primary tumor have a poor prognosis.

PATIENTS AND METHODS

Tissue samples from the most invasive part of the primary tumor of 710 patients (52% Stage II, 48% Stage III) participating in the VICTOR trial were analyzed for their tumor-stroma percentage. Stroma-high (>50%) and stroma-low (≤50%) groups were evaluated with respect to survival times.

RESULTS

Overall and disease-free survival times (OS and DFS) were significantly lower in the stroma-high group (OS P<0.0001, hazard ratio (HR)=1.96; DFS P<0.0001, HR=2.15). The 5-year OS was 69.0% versus 83.4% and DFS 58.6% versus 77.3% for stroma-high versus stroma-low patients.

CONCLUSION

This study confirms the intra-tumor stroma ratio as a prognostic factor. This parameter could be a valuable and low cost addition to the TNM status and next to current high-risk parameters such as microsatellite instability status used in routine pathology reporting. When adding the stroma-parameter to the ASCO criteria, the rate of 'undertreated' patients dropped from 5.9% to 4.3%, the 'overtreated' increased with 6.8% but the correctly classified increased with an additional 14%.

Pharmacological inhibition of Mdm2 triggers growth arrest and promotes DNA breakage in mouse colon tumors and human colon cancer cells

The p53 tumor suppressor protein performs a number of cellular functions, ranging from the induction of cell cycle arrest and apoptosis to effects on DNA repair. Modulating p53 activity with Mdm2 inhibitors is a promising approach for treating cancer; however, it is presently unclear how the in vivo application of Mdm2 inhibitors impact the myriad processes orchestrated by p53. Since approximately half of all colon cancers (predominately cancers with microsatellite instability) are p53-normal, we assessed the anticancer activity of the Mdm2 inhibitor Nutlin-3 in the mouse azoxymethane (AOM) colon cancer model, in which p53 remains wild type. Using a cell line derived from an AOM-induced tumor, we found that four daily exposures to Nutlin-3 induced persistent p53 stabilization and cell cycle arrest without significant apoptosis. A 4-day dosing schedule in vivo generated a similar response in colon tumors; growth arrest without significantly increased apoptosis. In adjacent normal colon tissue, Nutlin-3 treatment reduced both cell proliferation and apoptosis. Surprisingly, Nutlin-3 induced a transient DNA damage response in tumors but not in adjacent normal tissue. Nutlin-3 likewise induced a transient DNA damage response in human colon cancer cells in a p53-dependent manner, and enhanced DNA strand breakage and cell death induced by doxorubicin. Our findings indicate that Mdm2 inhibitors not only trigger growth arrest, but may also stimulate p53's reported ability to slow homologous recombination repair. The potential impact of Nutlin-3 on DNA repair in tumors suggests that Mdm2 inhibitors may significantly accentuate the tumoricidal actions of certain therapeutic modalities.