Somatic profiling of the epidermal growth factor receptor pathway in tumors from patients with advanced colorectal cancer treated with chemotherapy ± cetuximab

Prognostic and predictive biomarkers for anti-EGFR monoclonal antibody therapy in RAS wild-type metastatic colorectal cancer: a systematic review and meta-analysis

BACKGROUND

RAS mutations affect prognosis in patients with metastatic colorectal cancer (mCRC) and have been identified as strong negative predictive markers for anti-epidermal growth factor receptor monoclonal antibody (anti-EGFR mAb) therapy, but many tumors containing wild-type RAS genes still do not respond to these therapies. Some additional biomarkers may have prognostic or predictive roles, but conclusions remain controversial.

METHODS

We performed a meta-analysis and systematic review of randomized controlled trials comparing anti-EGFR mAb therapy with alternative therapy that investigated the prognostic and predictive impact of additional biomarkers in RAS wild-type (wt) mCRC patients. Hazard ratios (HRs) and 95% confidence intervals (CIs) for progression-free survival (PFS) and overall survival (OS) and odds ratios (ORs) for objective response rate (ORR) were calculated. The prognostic value of biomarkers was investigated by separately pooling HR and OR for different treatment groups in an individual study. The predictive value was assessed by pooling study interactions between treatment effects and biomarker subgroups.

RESULTS

Thirty publications reporting on eighteen trials were selected, including a total of 13,507 patients. In prognostic analysis, BRAF mutations were associated with poorer PFS [HRs = 3.76 (2.47-5.73) and 2.69 (1.82-3.98)] and OS [HRs = 2.66 (1.95-3.65) and 2.45 (1.55-3.88)] in both the experimental and control arms; low miR-31-3p expression appeared to have longer PFS and OS. In terms of predictive effect, a lack of response to anti-EGFR therapy was observed in patients with BRAF mutant tumors (Pinteraction < 0.01 for PFS). Patients with tumors with any mutation in the KRAS/NRAS/BRAF/PIK3CA gene also showed similar results compared with all wild-type tumors (Pinteraction for PFS, OS, and ORR were < 0.01, < 0.01 and 0.01, respectively). While low miR-31-3p expression could predict PFS (Pinteraction = 0.01) and OS (Pinteraction = 0.04) benefit. The prognostic and predictive value regarding PIK3CA mutations, PTEN mutations or deletions, EGFR, EREG/AREG, HER2, HER3, and HER4 expression remains uncertain.

CONCLUSIONS

In RAS wt mCRC patients receiving EGFR-targeted therapy, BRAF mutation is a powerful prognostic and therapy-predictive biomarker, with no effect found for PIK3CA mutation, PTEN mutation or deletion, but the combined biomarker KRAS/NRAS/BRAF/PIK3CA mutations predict resistance to anti-EGFR therapy. Low miR-31-3p expression may have positive prognostic and therapy predictive effects. Evidence on the prognostic and predictive roles of EGFR and its ligands, and HER2/3/4 is insufficient.

Predictive Genetic Biomarkers for the Development of Peritoneal Metastases in Colorectal Cancer

Metastatic colorectal cancer (CRC) is a common cause of cancer-related mortality, of which peritoneal metastases (PMs) have the worse outcome. Metastasis-specific markers may help predict the spread of tumor cells and select patients for preventive strategies. This exploratory pilot study aimed to gain more insight into genetic alterations in primary CRC tumors, which might be a predictive factor for the development of PM. Forty patients with T3 stage CRC were retrospectively divided in three groups: without metachronous metastases during 5-year follow-up (M0, n = 20), with metachronous liver metastases (LM, n = 10) and with metachronous PM (PM, n = 10). Patients with synchronous metastases were excluded. Primary formalin-fixed paraffin-embedded tumor samples were analyzed via comprehensive genome sequencing (TSO500 analysis) to identify DNA alterations and RNA fusion transcripts in 523 genes and 55 genes, respectively. Thirty-eight samples were included for final analysis. Four M0 tumors and one PM tumor were microsatellite instable. BRAF mutations were uniquely identified in three microsatellite-stable (MSS) PM tumors (37.5%, p = 0.010). RNA analysis showed an additional FAM198A-RAF1 fusion in one PM sample. BRAF p.V600E mutations were only present in PM patients with MSS tumors. Greater attention should be paid to BRAF-mutated tumors in relation to the development of metachronous PM.

Prognostic biomarkers in metastatic colorectal cancer: delta prognostic nutritional index, delta neutrophil to lymphocyte ratio, and delta platelet to lymphocyte ratio

BACKGROUND

The aim of this study is to determine the prognostic value of the prognostic nutritional index (PNI), the neutrophil to lymphocyte ratio (NLR), and the platelet to lymphocyte ratio (PLR) and their dynamic changes on survival outcomes in metastatic colorectal cancers (mCRC).

METHODS

The data of 199 patients with mCRC were retrospectively analyzed. To evaluate the temporal relation between the PNI, NLR, and PLR values and survival, pre-chemotherapy PNI, NLR, and PLR levels were assessed from peripheral blood cell counts on admission; post-chemotherapy PNI, NLR, and PLR levels were assessed with follow-up blood cell counts within two weeks after chemotherapy; and the difference between pre-chemotherapy PNI, NLR, and PLR levels and post-chemotherapy PNI, NLR, and PLR levels was evaluated as delta PNI, delta NLR, and delta PLR.

RESULTS

The median PNI, PLR, and NLR were 39.01, 150.2 and 2.53 before chemotherapy and 38.2, 146.6, and 3.31 after chemotherapy, respectively. The median OS was 23.7 months (95%CI:17.8-29.7) and 28.9 months (95%CI:24.8-33.08) for pre-chemotherapy PNI level < 39.01 vs. PNI level ≥ 39.01, respectively(p = 0.035) The positive delta PNI was significantly higher for OS than the negative delta PNI(p < 0.009). Delta PLR and delta NLR were not significant for OS and PFS(p > 0.05 for all).

CONCLUSIONS

The results of this study clearly show that the negative delta PNI to be an independent predictor of poor OS and poor PFS in patients with colon cancer who received first line treatment. In addition, delta NLR and delta PLR were shown not to predict survival outcomes.

DNA and RNA Alterations Associated with Colorectal Peritoneal Metastases: A Systematic Review

BACKGROUND

As colorectal cancer (CRC) patients with peritoneal metastases (PM) have a poor prognosis, new treatment options are currently being investigated for CRC patients. Specific biomarkers in the primary tumor could serve as a prediction tool to estimate the risk of distant metastatic spread. This would help identify patients eligible for early treatment.

AIM

To give an overview of previously studied DNA and RNA alterations in the primary tumor correlated to colorectal PM and investigate which gene mutations should be further studied.

METHODS

A systematic review of all published studies reporting genomic analyses on the primary tissue of CRC tumors in relation to PM was undertaken according to PRISMA guidelines.

RESULTS

Overall, 32 studies with 18,906 patients were included. BRAF mutations were analyzed in 17 articles, of which 10 found a significant association with PM. For all other reported genes, no association with PM was found. Two analyses with broader cancer panels did not reveal any new biomarkers.

CONCLUSION

An association of specific biomarkers in the primary tumors of CRC patients with metastatic spread into peritoneum could not be proven. The role of BRAF mutations should be further investigated. In addition, studies searching for potential novel biomarkers are still required.

Development and validation of a nomogram for predicting metachronous peritoneal metastasis in colorectal cancer: A retrospective study

BACKGROUND

Peritoneal metastasis (PM) after primary surgery for colorectal cancer (CRC) has the worst prognosis. Prediction and early detection of metachronous PM (m-PM) have an important role in improving postoperative prognosis of CRC. However, commonly used imaging methods have limited sensitivity to detect PM early. We aimed to establish a nomogram model to evaluate the individual probability of m-PM to facilitate early interventions for high-risk patients.

AIM

To establish and validate a nomogram model for predicting the occurrence of m-PM in CRC within 3 years after surgery.

METHODS

We used the clinical data of 878 patients at the Second Hospital of Jilin University, between January 1, 2014 and January 31, 2019. The patients were randomly divided into training and validation cohorts at a ratio of 2:1. The least absolute shrinkage and selection operator (LASSO) regression was performed to identify the variables with nonzero coefficients to predict the risk of m-PM. Multivariate logistic regression was used to verify the selected variables and to develop the predictive nomogram model. Harrell’s concordance index, receiver operating characteristic curve, Brier score, and decision curve analysis (DCA) were used to evaluate discrimination, distinctiveness, validity, and clinical utility of this nomogram model. The model was verified internally using bootstrapping method and verified externally using validation cohort.

RESULTS

LASSO regression analysis identified six potential risk factors with nonzero coefficients. Multivariate logistic regression confirmed the risk factors to be independent. Based on the results of two regression analyses, a nomogram model was established. The nomogram included six predictors: Tumor site, histological type, pathological T stage, carbohydrate antigen 125, v-raf murine sarcoma viral oncogene homolog B mutation and microsatellite instability status. The model achieved good predictive accuracy on both the training and validation datasets. The C-index, area under the curve, and Brier scores were 0.796, 0.796 [95% confidence interval (CI) 0.735-0.856], and 0.081 for the training cohort and 0.782, 0.782 (95%CI 0.690-0.874), and 0.089 for the validation cohort, respectively. DCA showed that when the threshold probability was between 0.01 and 0.90, using this model to predict m-PM achieved a net clinical benefit.

CONCLUSION

We have established and validated a nomogram model to predict m-PM in patients undergoing curative surgery, which shows good discrimination and high accuracy.

DEPDC1B promotes colorectal cancer via facilitating cell proliferation and migration while inhibiting apoptosis

Colorectal cancer (CRC) is a common malignant tumor with strong invasiveness. Given the reported involvement of DEP domain-containing protein 1B (DEPDC1B) in the progression of some cancers, its role in CRC was explored in this study. DEPDC1B expression in CRC was assessed based on database and tissue microarray (TMA). In addition, the knockdown and overexpression of DEPDC1B in CRC cell lines were constructed using small hairpin RNA (shRNA) interference. The biological function of DEPDC1B in CRC was evaluated in vitro and in vivo through loss/gain-of-function assays. The results demonstrated that DEPDC1B was highly expressed in CRC. Furthermore, DEPDC1B had the ability to promote CRC proliferation and migration coupled by cell apoptosis. In vivo results showed that DEPDC1B knockdown significantly inhibited the growth of xenograft tumors. Additionally, the results of antibody array indicated increased apoptosis-promoting proteins and decreased apoptosis-inhibiting proteins in DEPDC1B-knockdown CRC cells. In conclusion, DEPDC1B played a key driver role in CRC progression, and inhibition of its expression may be a potential target for precision medicine in CRC.

Stage-dependent prognostic shift in mismatch repair-deficient tumors: Assessing patient outcomes in stage II and III colon cancer

Introduction

Deficient mismatch repair (dMMR) or high microsatellite instability (MSI-H) is associated with an improved prognosis in colon cancer stage II but poor prognosis in stage IV colon cancer. The clinical significance of dMMR in colon cancer stage III is not established.

Methods

Tissue microarrays (TMAs) from 544 patients with colon cancer stage II and III with clinicopathological and survival data were stained for mismatch repair (MMR) proteins, CD3, CD8, and programmed death ligand-1 (PD-L1), and programmed death ligand- 1 (PD-L1). Patient outcomes were reviewed.

Results

In stage III colon cancer, dMMR was a marker of poor disease-free survival (DFS) (Kaplan–Meier, mean survival in months: dMMR: 28.76 (95% CI 18.46–39.05) vs. pMMR 40.91 (37.20–44.63), p=0.014, multivariate Cox regression: hazard ratio (HR) 4.17 (95% CI 2.02–8.61), p<0.001). In stage II colon cancer, there was a tendency toward improved DFS for dMMR patients (dMMR: 57.14 (95% CI 54.66–59.62) vs. pMMR 53.54 (95% CI 51.48–55.60), p=0.015, multivariate Cox regression HR 0.24 (95% CI 0.06-1.04), p=0.057). CD3, CD8, and PD-L1 expression was not associated with prognosis of dMMR patients. Multivariate Cox regression analysis showed a significant interaction between the MMR phenotype and stage (p=0.001).

Conclusion

dMMR is associated with an improved prognosis in stage II colon cancer but is no longer associated with a favorable prognosis in stage III colon cancer.

Microsatellite Instability: From the Implementation of the Detection to a Prognostic and Predictive Role in Cancers

Microsatellite instability (MSI) has been identified in several tumors arising from either germline or somatic aberration. The presence of MSI in cancer predicts the sensitivity to immune checkpoint inhibitors (ICIs), particularly PD1/PD-L1 inhibitors. To date, the predictive role of MSI is currently used in the selection of colorectal cancer patients for immunotherapy; moreover, the expansion of clinical trials into other cancer types may elucidate the predictive value of MSI for non-colorectal tumors. In clinical practice, several assays are used for MSI testing, including immunohistochemistry (IHC), polymerase chain reaction (PCR) and next-generation sequencing (NGS). In this review, we provide an overview of MSI in various cancer types, highlighting its potential predictive/prognostic role and the clinical trials performed. Finally, we focus on the comparison data between the different assays used to detect MSI in clinical practice.

A Systematic Review and Meta-analysis on the Occurrence of Biomarker Mutation in Colorectal Cancer among the Asian Population

Globally, colorectal carcinoma (CRC) is the third most common cancer and the third major cause of cancer-related death in both sexes. KRAS and BRAF mutations are almost mutually exclusively involved in the pathogenesis of CRC. Both are major culprits in treatment failure and poor prognosis for CRC. Method. A systematic review and meta-analysis of various research was done following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. This trial is registered with PROSPERO CRD42021256452. The initial search included 646 articles; after the removal of noneligible studies, a total of 88 studies was finally selected. Data analysis was carried out using OpenMeta Analyst and Comprehensive Meta-Analysis 3.0 (CMA 3.0) software to investigate the prevalence of KRAS and BRAF mutations among patients with CRC in Asia. Results. The meta-analysis comprises of 25,525 sample sizes from Asia with most being male 15,743/25525 (61.7%). Overall prevalence of KRAS mutations was (59/88) 36.3% (95% CI: 34.5-38.2) with I² = 85.54% (P value < 0.001). In 43/59 studies, frequency of KRAS mutations was majorly in codon 12 (76.6% (95% CI: 74.2–78.0)) and less in codon 13 (21.0% (95% CI: 19.1-23.0)). Overall prevalence of BRAF mutations was 5.6% (95% CI: 3.9-8.0) with I² = 94.00% (P value < 0.001). When stratified according to location, a higher prevalence was observed in Indonesia (71.8%) while Pakistan has the lowest (13.5%). Conclusion. Total prevalence of KRAS and BRAF mutations in CRC was 36.6% and 5.6%, respectively, and the results conformed with several published studies on KRAS and BRAF mutations.

Risk Factors for Synchronous Peritoneal Metastases in Colorectal Cancer: A Systematic Review and Meta-Analysis

Background

Early detection of synchronous colorectal peritoneal metastases (CPMs) is difficult due to the absence of typical symptoms and the low accuracy of imaging examinations. Increasing the knowledge of the risk factors for synchronous CPM may be essential for early diagnosis and improving their management. This study aimed to identify the risk factors for synchronous CPM.

Method

The study was registered at PROSPERO (CRD42020198548). The PubMed, Embase and Cochrane Library databases were searched for studies comparing the clinicopathological and molecular features between patients with or without synchronous CPM. The pooled data were assessed by a random-effects model.

Results

Twenty-five studies were included. A synchronous CPM was positively associated with female sex (OR 1.299; 1.118 to 1.509; P = 0.001), PROK1/PROKR2-positivity (OR 2.244; 1.031 to 4.884; P = 0.042), right-sided colon cancer (OR 2.468; 2.050 to 2.970; P < 0.001), poorly differentiated grade (OR 2.560; 1.537 to 4.265; P < 0.001), BRAF mutation (OR 2.586; 1.674 to 3.994; P < 0.001), mucinous adenocarcinoma (OR 3.565; 2.095 to 6.064; P < 0.001), signet-ring cell carcinoma (OR 4.480; 1.836 to 10.933; P = 0.001), N1-2 (OR 5.665; 3.628 to 8.848; P < 0.001), T4 (OR 12.331; 7.734 to 19.660; P < 0.001) and elevated serum CA19-9 (OR 12.868; 5.196 to 31.867; P < 0.001).

Conclusions

These evidence-based risk factors are indicators that could predict the presence of synchronous CPMs and can improve their management.

Systematic Review Registration

www.crd.york.ac.uk/prospero, identifier: CRD42020198548.

The impact of molecular and mismatch repair status on the survival outcomes of surgically treated patients with colorectal peritoneal metastases

BACKGROUND

Stratification of patients with colorectal peritoneal metastases (CRPM) using RAS/BRAF mutational status may refine patient selection for cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC). This study aimed to analyse the association of RAS/BRAF status and their variants, with clinicopathological variables and survival outcomes in patients who have undergone CRS ± HIPEC.

METHODS

A single centre, peritonectomy database was interrogated for patients with CRPM who underwent peritonectomy procedures between 2010 and 2020.

RESULTS

During the study period, 174 patients were included. Molecular status was obtained on 169 patients, with 68 (40.5%) KRAS, 25 (14.8%) BRAF and 6 (3.6%) NRAS mutations detected. Patients with BRAF mutations were more likely to be mismatch repair deficient (dMMR) (BRAF 20%, KRAS 4.4%, wild type 8.6%, p = 0.015). Most common BRAF and KRAS variants were, V600E (80%) and G12D (39.7%), respectively. BRAF V600E was independently associated with worse overall (median: 28 months, multivariate: HR 2.29, p = 0.026) and disease-free survival (median: 8 months, multivariate: HR 1.8, p = 0.047). KRAS G12V was a strong prognostic factor associated with disease-free survival (median: 9 months, HR 2.63, p = 0.016). dMMR patients (14/161, 8.7%) exhibited worse median overall survival compared to those with proficient MMR (dMMR 27 months, pMMR 29 months p = 0.025).

CONCLUSION

This study highlights the importance of molecular analysis in CRPM stratification. BRAF V600E mutations predict poor outcomes post CRS and HIPEC and may help refine patient selection for this procedure. Molecular analysis should be performed preoperatively to characterise prognosis and guide perioperative therapeutic options.

Metastatic colorectal carcinoma with signet-ring cells: Clinical, histological and molecular description from an Association des Gastro-Entérologues Oncologues (AGEO) French multicenter retrospective cohort

BACKGROUND

Metastatic signet-ring cell colorectal carcinoma is rare. We analyzed its clinicopathological and molecular features, prognostic factors and chemosensitivity.

METHODS

Retrospective study from 2003 to 2017 in 31 French centers, divided into three groups: curative care (G1), chemotherapy alone (G2), and best supportive care (G3).

RESULTS

Tumors were most frequently in the proximal colon (46%), T4 (71%), and poorly differentiated (86%). The predominant metastatic site was peritoneum (69%). Microsatellite instability and BRAF mutation were found in 19% and 9% (mainly right-sided) of patients and RAS mutations in 23%. Median overall survival (mOS) of the patients (n = 204) was 10.1 months (95%CI: 7.9;12.8), 45.1 for G1 (n = 38), 10.9 for G2 (n = 112), and 1.8 months for G3 (n = 54). No difference in mOS was found when comparing tumor locations, percentage of signet-ring cell contingent and microsatellite status. In G1, relapse-free survival was 14 months (95%CI: 6.5-20.9). In G2, median progression-free survival (PFS) was 4.7 months (95%CI: 3.6;5.9]) with first-line treatment. Median PFS was higher with biological agents than without (5.0 vs 3.9 months, p = 0.016).

CONCLUSIONS

mSRCC has a poor prognosis with specific location and molecular alterations resulting in low chemosensitivity. Routine microsatellite analysis should be performed because of frequent MSI-high tumors in this population.

Microsatellite and RAS/RAF Mutational Status as Prognostic Factors in Colorectal Peritoneal Metastases Treated with Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy (HIPEC)

BACKGROUND

Cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) leads to prolonged survival for selected patients with colorectal (CRC) peritoneal metastases (PM). This study aimed to analyze the prognostic role of micro-satellite (MS) status and RAS/RAF mutations for patients treated with CRS.

METHODS

Data were collected from 13 Italian centers with PM expertise within a collaborative group of the Italian Society of Surgical Oncology. Clinical and pathologic variables and KRAS/NRAS/BRAF mutational and MS status were correlated with overall survival (OS) and disease-free survival (DFS).

RESULTS

The study enrolled 437 patients treated with CRS-HIPEC. The median OS was 42.3 months [95% confidence interval (CI), 33.4-51.2 months], and the median DFS was 13.6 months (95% CI, 12.3-14.9 months). The local (peritoneal) DFS was 20.5 months (95% CI, 16.4-24.6 months). In addition to the known clinical factors, KRAS mutations (p = 0.005), BRAF mutations (p = 0.01), and MS status (p = 0.04) were related to survival. The KRAS- and BRAF-mutated patients had a shorter survival than the wild-type (WT) patients (5-year OS, 29.4% and 26.8% vs 51.5%, respectively). The patients with micro-satellite instability (MSI) had a longer survival than the patients with micro-satellite stability (MSS) (5-year OS, 58.3% vs 36.7%). The MSI/WT patients had the best prognosis. The MSS/WT and MSI/mutated patients had similar survivals, whereas the MSS/mutated patients showed the worst prognosis (5-year OS, 70.6%, 48.1%, 23.4%; p = 0.0001). In the multivariable analysis, OS was related to the Peritoneal Cancer Index [hazard ratio (HR), 1.05 per point], completeness of cytoreduction (CC) score (HR, 2.8), N status (HR, 1.6), signet-ring (HR, 2.4), MSI/WT (HR, 0.5), and MSS/WT-MSI/mutation (HR, 0.4). Similar results were obtained for DFS.

CONCLUSION

For patients affected by CRC-PM who are eligible for CRS, clinical and pathologic criteria need to be integrated with molecular features (KRAS/BRAF mutation). Micro-satellite status should be strongly considered because MSI confers a survival advantage over MSS, even for mutated patients.

Mismatch Repair Status in Patient-Derived Colorectal Cancer Organoids Does Not Affect Intrinsic Tumor Cell Sensitivity to Systemic Therapy

DNA mismatch repair deficiency (dMMR) in metastatic colorectal cancer (mCRC) is associated with poor survival and a poor response to systemic treatment. However, it is unclear whether dMMR results in a tumor cell-intrinsic state of treatment resistance, or whether alternative mechanisms play a role. To address this, we generated a cohort of MMR-proficient and -deficient Patient-Derived Organoids (PDOs) and tested their response to commonly used drugs in the treatment of mCRC, including 5-fluorouracil (5-FU), oxaliplatin, SN-38, binimetinib, encorafenib, and cetuximab. MMR status did not correlate with the response of PDOs to any of the drugs tested. In contrast, the presence of activating mutations in the KRAS and BRAF oncogenes was significantly associated with resistance to chemotherapy and sensitivity to drugs targeting oncogene-activated pathways. We conclude that mutant KRAS and BRAF impact the intrinsic sensitivity of tumor cells to chemotherapy and targeted therapy. By contrast, tumor cell-extrinsic mechanisms-for instance signals derived from the microenvironment-must underlie the association of MMR status with therapy response. Future drug screens on rationally chosen cohorts of PDOs have great potential in developing tailored therapies for specific CRC subtypes including, but not restricted to, those defined by BRAF/KRAS and MMR status.

Precision oncology in metastatic colorectal cancer - from biology to medicine

Remarkable progress has been made in the development of biomarker-driven targeted therapies for patients with multiple cancer types, including melanoma, breast and lung tumours, although precision oncology for patients with colorectal cancer (CRC) continues to lag behind. Nonetheless, the availability of patient-derived CRC models coupled with in vitro and in vivo pharmacological and functional analyses over the past decade has finally led to advances in the field. Gene-specific alterations are not the only determinants that can successfully direct the use of targeted therapy. Indeed, successful inhibition of BRAF or KRAS in metastatic CRCs driven by activating mutations in these genes requires combinations of drugs that inhibit the mutant protein while at the same time restraining adaptive resistance via CRC-specific EGFR-mediated feedback loops. The emerging paradigm is, therefore, that the intrinsic biology of CRC cells must be considered alongside the molecular profiles of individual tumours in order to successfully personalize treatment. In this Review, we outline how preclinical studies based on patient-derived models have informed the design of practice-changing clinical trials. The integration of these experiences into a common framework will reshape the future design of biology-informed clinical trials in this field.

Perspectives on Immunotherapy of Metastatic Colorectal Cancer

Colorectal cancer, especially liver metastasis, is still a challenge worldwide. Traditional treatment such as surgery, chemotherapy and radiotherapy have been difficult to be further advanced. We need to develop new treatment methods to further improve the poor prognosis of these patients. The emergence of immunotherapy has brought light to mCRC patients, especially those with dMMR. Based on several large trials, some drugs (pembrolizumab, nivolumab) have been approved by US Food and Drug Administration to treat the patients diagnosed with dMMR tumors. However, immunotherapy has reached a bottleneck for other MSS tumors, with low response rate and poor PFS and OS. Therefore, more clinical trials are underway toward mCRC patients, especially those with MSS. This review is intended to summarize the existing clinical trials to illustrate the development of immunotherapy in mCRC patients, and to provide a new thinking for the direction and experimental design of immunotherapy in the future.

Histopathological Growth Patterns and Survival After Resection of Colorectal Liver Metastasis: An External Validation Study

Background

After resection of colorectal cancer liver metastases (CRLM), 2 main histopathological growth patterns can be observed: a desmoplastic and a nondesmoplastic subtype. The desmoplastic subtype has been associated with superior survival. These findings require external validation.

Methods

An international multicenter retrospective cohort study was conducted in patients treated surgically for CRLM at 3 tertiary hospitals in the United States and the Netherlands. Determination of histopathological growth patterns was performed on hematoxylin and eosin-stained sections of resected CRLM according to international guidelines. Patients displaying a desmoplastic histopathological phenotype (only desmoplastic growth observed) were compared with patients with a nondesmoplastic phenotype (any nondesmoplastic growth observed). Cutoff analyses on the extent of nondesmoplastic growth were performed. Overall survival (OS) and disease-free survival (DFS) were estimated using Kaplan-Meier and multivariable Cox analysis. All statistical tests were 2-sided.

Results

In total 780 patients were eligible. A desmoplastic phenotype was observed in 19.1% and was associated with microsatellite instability (14.6% vs 3.6%, P = .01). Desmoplastic patients had superior 5-year OS (73.4%, 95% confidence interval [CI] = 64.1% to 84.0% vs 44.2%, 95% CI = 38.9% to 50.2%, P < .001) and DFS (32.0%, 95% CI = 22.9% to 44.7% vs 14.7%, 95% CI = 11.7% to 18.6%, P < .001) compared with their nondesmoplastic counterparts. A desmoplastic phenotype was associated with an adjusted hazard ratio for death of 0.36 (95% CI = 0.23 to 0.58) and 0.50 (95% CI = 0.37 to 0.66) for cancer recurrence. Prognosis was independent of KRAS and BRAF status. The cutoff analyses found no prognostic relationship between either OS or DFS and the extent of nondesmoplastic growth observed (all P > .1).

Conclusions

This external validation study confirms the remarkably good prognosis after surgery for CRLM in patients with a desmoplastic phenotype. The extent of nondesmoplastic growth does not affect prognosis.

KRAS and BRAF mutations in Iranian colorectal cancer patients: A systematic review and meta-analysis

Background:

Mutations in the EGFR signaling pathway play an important role in the development of colorectal cancer (CRC). Mutations in these genes, like KRAS and BRAF, affect the treatment strategies and associated with poor prognosis and relative resistance to anti-EGFR therapies. Our aim was to conduct a systematic and meta-analysis on all studies that have been conducted on the prevalence of these gene mutations in Iranian CRC patients.

Methods:

Four science citation index databases (MEDLINE, EMBASE, Web of Science and Cochrane library) and local databases were searched up to March 2018 with related keywords. Two reviewers independently screened and extracted the data. Quality of all included studies was assessed using an adapted checklist from STROBE. A random-effect model was used to calculate the total prevalence of KRAS and BRAF mutations in CRC subjects by the event rate (ER). Meta-regression was utilized to explore heterogeneity causes.

Results:

In total, from 573 records, 23 eligible studies (2662 patients) were included for data extraction and analysis. In 18 of 23 included studies, the prevalence of KRAS mutations was 33.9% (95% CI=30.1-37.9) with I2=65.17 (p<0.001). The occurrence of KRAS mutations in codon 12 and 13 was 76.9% (95% CI = 70.4-82.3%) with I2=84.88 (p<0.001) and 23.5% (95% CI=17.9-30.3) with I2=85.85 (p<0.001), respectively. In 9 of 23 studies, the BRAF mutation rate was 3.2% (95% CI=0.003-13.6) with I2=88.61 (p<0.001).

Conclusion:

The prevalence of these mutations in CRC patients shows a significant difference in the different regions of Iran, which is probably due to environmental and racial factors.

A review of the sensitivity of metastatic colorectal cancer patients with deficient mismatch repair to standard-of-care chemotherapy and monoclonal antibodies, with recommendations for future research

In 5% of metastatic colorectal cancer (mCRC) patients, tumours display a deficient mismatch repair (dMMR) system. Immunotherapy is beneficial in dMMR mCRC patients and has recently been approved by the Food and Drug Administration for patients with unresectable or metastatic dMMR CRC. Although dMMR and proficient MMR (pMMR) CRC tumours are biologically distinct, they are commonly treated with the same chemotherapy and monoclonal antibodies. This includes dMMR mCRC patients who did not respond to immunotherapy (20-30%). However, it is unclear if these treatments are equally beneficial in dMMR mCRC. Of note, dMMR mCRC patients have a worse prognosis compared to pMMR, which may in part be caused by a lower response to treatment. To avoid unnecessary exposure to ineffective treatments and their associated toxicity, it is important to identify which systemic treatments are most beneficial in dMMR mCRC patients, thus improving their outcome. Indeed, future treatment strategies are likely to involve combinations of immunotherapy, chemotherapy and monoclonal antibodies. In this evidence-based review, we summarize clinical trials reporting treatment efficacy of different types of chemotherapy and monoclonal antibodies in dMMR mCRC patients. We also review the biological rationale behind a potential differential benefit of chemotherapy with or without monoclonal antibodies in dMMR mCRC patients. A barrier in the interpretation of preclinical results is the choice of model systems. They largely comprise traditional models, including cell lines and xenografts, rather than more representative models, such as patient-derived organoids. We provide concrete recommendations for clinical investigators and fundamental researchers to accelerate research regarding which systemic therapy is most effective in dMMR mCRC patients.

BRAF Mutation in Colorectal Cancers: From Prognostic Marker to Targetable Mutation

Simple Summary

Colorectal cancer with a mutation in an oncogene BRAF has paid much attention, as it comprises a population with dismal prognosis since two decades ago. A series of research since then has successfully changed this malignancy to be treatable with specific treatment. Here we thoroughly overviewed the basic, translational and clinical studies on colorectal cancer with BRAF mutation from a physician’s viewpoint. Accumulating lines of evidence suggest that intervention of the trunk cellular growth signal transduction pathway, namely EGFR-RAS-RAF-MEK-ERK pathway, is a clue to controlling this disease. However, it is not so straightforward. Recent studies unveil the diverse and plastic nature of this signal transduction pathway. We will introduce our endeavor to conquer this condition, based on newly arriving datasets, and discuss how we could open the door to future development of CRC treatment.

Abstract

The Raf murine sarcoma viral oncogene homolog B (BRAF) mutation is detected in 8–12% of metastatic colorectal cancers (mCRCs) and is strongly correlated with poor prognosis. The recent success of the BEACON CRC study and the development of targeted therapy have led to the determination of BRAF-mutated mCRCs as an independent category. For nearly two decades, a growing body of evidence has established the significance of the BRAF mutation in the development of CRC. Herein, we overview both basic and clinical data relevant to BRAF-mutated CRC, mainly focusing on the development of treatment strategies. This review is organized into eight sections, including clinicopathological features, molecular features, prognosis, the predictive value of anti-epidermal growth factor receptor (EGFR) therapy, resistant mechanisms for BRAF-targeting treatment, the heterogeneity of the BRAF mutation, future perspectives, and conclusions. A characterization of the canonical mitogen-activated protein kinase (MAPK) pathway is essential for controlling this malignancy, and the optimal combination of multiple interventions for treatments remains a point of debate.

Characterization of Chilean patients with sporadic colorectal cancer according to the three main carcinogenic pathways: Microsatellite instability, CpG island methylator phenotype and Chromosomal instability

Molecular classification of colorectal cancer is difficult to implement in clinical settings where hundreds of genes are involved, and resources are limited. This study aims to characterize the molecular subtypes of patients with sporadic colorectal cancer based on the three main carcinogenic pathways microsatellite instability (MSI), CpG island methylator phenotype (CIMP), and chromosomal instability (CIN) in a Chilean population. Although several reports have characterized colorectal cancer, most do not represent Latin-American populations. Our study includes 103 colorectal cancer patients who underwent surgery, without neoadjuvant treatment, in a private hospital between 2008 and 2017. MSI, CIN, and CIMP status were assessed. Frequent mutations in KRAS, BRAF, and PIK3CA genes were analyzed by Sanger sequencing, and statistical analysis was performed by Fisher's exact and/or chi-square test. Survival curves were estimated with Kaplan-Meier and log-rank test. Based on our observations, we can classify the tumors in four subgroups, Group 1: MSI-high tumors (15%) are located in the right colon, occur at older age, and 60% show a BRAF mutation; Group 2: CIN-high tumors (38%) are in the left colon, and 26% have KRAS mutations. Group 3: [MSI/CIN/CIMP]-low/negative tumors (30%) are left-sided, and 39% have KRAS mutations; Group 4: CIMP-high tumors (15%) were more frequent in men and left side colon, with 27% KRAS and 7% presented BRAF mutations. Three percent of patients could not be classified. We found that CIMP-high was associated with a worse prognosis, both in MSI-high and MSI stable patients (p = 0.0452). Group 3 (Low/negative tumors) tend to have better overall survival compared with MSI-high, CIMP-high, and CIN-high tumors. This study contributes to understanding the heterogeneity of tumors in the Chilean population being one of the few characterizations performed in Latin-America. Given the limited resources of these countries, these results allow to improve molecular characterization in Latin-American colorectal cancer populations and confirm the possibility of using the three main carcinogenic pathways to define therapeutic strategies.

[BRAF V600E-mutant colorectal cancers: Where are we?]

The BRAF^V600E mutation, observed in 8 % of colorectal cancers (CRC), introduces a particular phenotype and a poor prognosis at the localized or metastatic stage. BRAF mutant CRCs are more often localized in the right colon, poorly differentiated and mucinous. They affect an older population (more often female) and are associated with a more frequent metastatic lymph node and peritoneal evolution. The BRAF^V600E mutation is associated with a sporadic microsatellite instability (MSI) status in 20 to 40% of cases. In localized colon cancer, it does not imply any modification of the adjuvant treatment. In metastatic CRC, the first action must be the systematic search for an MSI phenotype, given its frequent association with the presence of a BRAF mutation, in order to propose immunotherapy that has been demonstrated to be very effective in MSI metastatic CRC. In non-MSI CRC, a first-line trichimiotherapy associated with bevacizumab is an option to be favored in patients in good general condition but the association with an anti-EGFR can be discussed, especially when the objective is tumor response. At the same time, surgical resection must be systematically discussed in the case of resectable hepatic metastases since the presence of a BRAF^V600E mutation is not a risk factor for recurrence and that prolonged survival may be observed after surgery. In the second or third line, the triplet encorafenib, binimetinib and cetuximab, as well as the doublet encorafenib and cetuximab are superior to the association of irinotecan plus cetuximab in terms of response and survival (phase III study BEACON) and represent a new therapeutic standard. Their use on the front line is under study.

Efficacy of Anti-EGFR in Microsatellite Instability Metastatic Colorectal Cancer Depending on Sporadic or Familial Origin

Anti-epidermal growth factor receptor (EGFR) efficacy in patients with microsatellite instability (MSI) metastatic colorectal cancer (mCRC) according to sporadic vs familial origin is unknown. We retrospectively analyzed 128 patients with MSI mCRC treated with first-line chemotherapy ± anti-EGFR. Among them, 61 and 67 patients were respectively categorized as familial and sporadic based on mismatch repair protein immunostaining, BRAF mutational status, and MLH1 promoter methylation status. We observed that addition of anti-EGFR to chemotherapy was associated with a statistically significant improvement of progression-free survival for familial (median = 5.0 vs 10.2 months, hazard ratio [HR] = 0.47, 95% confidence interval [CI] = 0.23 to 0.94; P = .03) but not for sporadic (median = 4.4 vs 5.4 months, HR = 0.80, 95% CI = 0.39 to 1.60; P = .52) MSI mCRC patients. In multivariate analysis, the survival benefit of adding anti-EGFR to chemotherapy remained statistically significant for familial MSI cases (P = .04). These findings deserve to be confirmed in a prospective study and could help decision making in MSI mCRC without access or resistant to immunotherapy.

Less correlation between mismatch repair proteins deficiency and decreased expression of HLA class I molecules in endometrial carcinoma: a different propensity from colorectal cancer

Mismatch repair protein deficiency (dMMR) is a favorable prognostic factor in colorectal cancer. It is also associated with aberrant expression of HLA class I molecules, which are required for cytotoxic T lymphocyte-mediated cancer immunotherapy. Because dMMR is frequently also found in endometrial cancers (ECs), we retrospectively investigated the expression of mismatch repair proteins and HLA class I molecules in 127 EC patients. In this study, EC patients being treated in our hospital were recruited from 2005 to 2009 and observed until December 2017. Lesion specimens were evaluated via immunohistochemistry for MSH6 and PMS2 (mismatch repair proteins) and HLA class I molecules. Expression of these molecules was statistically related to clinical and pathological factors and prognosis. dMMR was detected in 33 patients and did not correlate with the expression level of HLA class I molecules (P = 0.60). On the other hand, unexpectedly, multivariate analysis revealed that intact expression of HLA class I molecules was associated with p53 overexpression (P = 0.004). Neither dMMR nor decreased expression of HLA class I molecules were prognostic factors. These results are inconsistent with previous findings for colorectal cancer. A distinctive local tissue immune microenvironment would underlie the discrepancy in the results between EC and colorectal cancer.

Clinical Outcomes in Patients With Colon Cancer With Microsatellite Instability of Sporadic or Familial Origin Treated With Adjuvant FOLFOX With or Without Cetuximab: A Pooled Analysis of the PETACC8 and N0147 Trials

PURPOSE

The microsatellite instability (MSI) or deficient mismatch repair (dMMR) phenotype is usually regarded as a single biologic entity, given the absence of comparative analyses regarding prognosis and response to chemotherapy between sporadic and familial dMMR cancers.

PATIENTS AND METHODS

Patients with stage III colon cancers were randomly assigned to FOLFOX (leucovorin, fluorouracil, and oxaliplatin) with or without cetuximab in 2 large adjuvant phase III trials (N = 5,577). Among patients with MSI and KRAS exon 2 wild-type (WT) tumors, the prognostic and predictive impacts of sporadic versus familial dMMR cancers and BRAF V600E mutational status were determined. Multivariable Cox proportional hazards models were used to assess disease-free survival (DFS) by treatment arm, adjusting for age, sex, tumor grade, Eastern Cooperative Oncology Group performance status, pT/pN stage, and primary tumor location.

RESULTS

Among patients with MSI status with complete data for dMMR mechanism analysis (n = 354), 255 (72%) had sporadic (BRAF mutation and/or MLH1 methylation) and 99 (28%) had familial tumors (BRAF WT and unmethylated MLH1 or loss of MSH2/MSH6/PMS2 protein expression). A large proportion of dMMR sporadic tumors were mutated for BRAF (n = 200). In patients treated with FOLFOX, DFS did not differ statistically by dMMR mechanism, whereas in patients treated with FOLFOX plus cetuximab, those with sporadic tumors had worse DFS than those with familial cancers (multivariable hazard ratio, 2.69; 95% CI, 1.02 to 7.08; P = .04). Considering the predictive utility, the interaction between treatment and dMMR mechanism was significant (P = .03). Furthermore, a nonsignificant trend toward a deleterious effect of adding cetuximab to FOLFOX was observed in patients with BRAF-mutant but not BRAF WT tumors.

CONCLUSION

The addition of cetuximab to adjuvant FOLFOX was associated with shorter DFS in patients with sporadic dMMR colon cancer. Additional studies are needed to validate these results in metastatic disease.

Comprehensive analysis of colorectal cancer-risk loci and survival outcome: A prognostic role for CDH1 variants

PURPOSE

Genome-wide association studies have identified common single nucleotide polymorphisms (SNPs) at 83 loci associated with colorectal cancer (CRC) risk in European populations. Because germline variation can also influence patient outcome, we studied the relationship between these SNPs and CRC survivorship.

EXPERIMENTAL DESIGN

For the 83 risk loci, 10 lead SNPs were directly genotyped, 72 were imputed and 1 was not genotyped nor imputed, in 1948 unrelated patients with advanced CRC from the clinical trials COIN and COIN-B (oxaliplatin and fluoropyrimidine chemotherapy ± cetuximab). A Cox survival model was used for each variant, and variants classified by pathway, adjusting for known prognostic factors. We imposed a Bonferroni threshold of P = 6.6 × 10-4 for multiple testing. We carried out meta-analyses of published risk SNPs associated with survival.

RESULTS

Univariate analysis identified six SNPs associated with overall survival (OS) (P < 0.05); however, only rs9939049 in CDH1 remained significant beyond the Bonferroni threshold (Hazard Ratio [HR] 1.44, 95% Confidence Intervals [CI]: 1.21-1.71, P = 5.0 × 10-5). Fine mapping showed that rs12597188 was the most significant SNP at this locus and remained significant after adjustment for known prognostic factors beyond multiple testing thresholds (HR 1.23, 95% CI: 1.13-1.34, P = 1.9 × 10-6). rs12597188 was also associated with poor response to therapy (OR 0.61, 95% CI: 0.42-0.87, P = 6.6 × 10-3). No combinations of SNPs within pathways were more significantly associated with survival compared with single variants alone, and no other risk SNPs were associated with survival in meta-analyses.

CONCLUSIONS

The CRC susceptibility SNP rs9939049 in CDH1 influences patient survival and warrants further evaluation as a prognostic biomarker.

Biomarker-guided therapy for colorectal cancer: strength in complexity

The number of molecularly stratified treatment options available to patients with colorectal cancer (CRC) is increasing, with a parallel rise in the use of biomarkers to guide prognostication and treatment decision-making. The increase in both the number of biomarkers and their use has resulted in a progressively complex situation, evident both from the extensive interactions between biomarkers and from their sometimes complex associations with patient prognosis and treatment benefit. Current and emerging biomarkers also reflect the genomic complexity of CRC, and include a wide range of aberrations such as point mutations, amplifications, fusions and hypermutator phenotypes, in addition to global gene expression subtypes. In this Review, we provide an overview of current and emerging clinically relevant biomarkers and their role in the management of patients with CRC, illustrating the intricacies of biomarker interactions and the growing treatment opportunities created by the availability of comprehensive molecular profiling.

The Disease-Free Interval Between Resection of Primary Colorectal Malignancy and the Detection of Hepatic Metastases Predicts Disease Recurrence But Not Overall Survival

Introduction

The disease-free interval (DFI) between resection of primary colorectal cancer (CRC) and diagnosis of liver metastases is considered an important prognostic indicator; however, recent analyses in metastatic CRC found limited evidence to support this notion.

Objective

The current study aims to determine the prognostic value of the DFI in patients with resectable colorectal liver metastases (CRLM).

Methods

Patients undergoing first surgical treatment of CRLM at three academic centers in The Netherlands were eligible for inclusion. The DFI was defined as the time between resection of CRC and detection of CRLM. Baseline characteristics and Kaplan–Meier survival estimates were stratified by DFI. Cox regression analyses were performed for overall (OS) and disease-free survival (DFS), with the DFI entered as a continuous measure using a restricted cubic spline function with three knots.

Results

In total, 1374 patients were included. Patients with a shorter DFI more often had lymph node involvement of the primary, more frequently received neoadjuvant chemotherapy for CRLM, and had higher number of CRLM at diagnosis. The DFI significantly contributed to DFS prediction (p =0.002), but not for predicting OS (p =0.169). Point estimates of the hazard ratio (95% confidence interval) for a DFI of 0 versus 12 months and 0 versus 24 months were 1.284 (1.114–1.480) and 1.444 (1.180–1.766), respectively, for DFS, and 1.111 (0.928–1.330) and 1.202 (0.933–1.550), respectively, for OS.

Conclusion

The DFI is of prognostic value for predicting disease recurrence following surgical treatment of CRLM, but not for predicting OS outcomes.

Electronic supplementary material

The online version of this article (10.1245/s10434-019-07481-x) contains supplementary material, which is available to authorized users.

Impact of Tumor Site on Lymph Node Status and Survival in Colon Cancer

Objective Our objective was to explore the impact of tumor sites on lymph node (LN) status and prognosis in non-distant metastasis colon cancer after radical operation.

Methods Surveillance, epidemiology, and end results (SEER) database was used to identify 124, 836 early-stage colon cancer patients between 1988 and 2010, treated with radical surgery with a known tumor site. Seven tumor sites were defined as ascending, hepatic, cecum, transverse, descending, splenic, and sigmoid colons by the anatomical location. The associations of tumor site and LN status, including adequate (≥12) LN harvest and LN positivity, were examined with logistic regression, adjusting for multiple covariates. Relative survival was compared in a flexible parametric model.

Results The quartile number of LN examined gradually decreased from ascending to sigmoid colon cancer (P<0.001 for all patients, and T2, T3 and T4 stages). More numbers of LN examined and a higher proportion of LN positivity were retrieved in left-half colon cancer than in right-half colon cancer. Cumulative incidence of death (CID) was higher in patients with less LN examined except for the group of cecum colon cancer, but there was no significant difference between all groups (5-year CID: 18.99%~21.98% for LN count ≥ 12 and 23.01%~26.89% for LN count <12).

Conclusions LN examined and LN positivity in colon cancer were important prognostic factors. There was no significant CDI difference between groups with different tumor sites. Current guidelines for extent of resection should take this into consideration so that and unnecessary treatment may be avoided.

Consequences of a high incidence of microsatellite instability and BRAF-mutated tumors: A population-based cohort of metastatic colorectal cancer patients

Background

Immunotherapy for patients with microsatellite‐instable (MSI‐H) tumors or BRAF‐inhibitors combination treatment for BRAF‐mutated (mutBRAF) tumors in metastatic colorectal cancer (mCRC) is promising, but the frequency of these molecular changes in trial patients are low. Unselected population‐based studies of these molecular changes are warranted.

Methods

A population‐based cohort of 798 mCRC patients in Scandinavia was studied. Patient and molecular tumor characteristics, overall survival (OS) and progression‐free survival (PFS) were estimated.

Results

Here, 40/583 (7%) tumor samples were MSI‐H and 120/591 (20%) were mutBRAF; 87% of MSI‐H tumors were mutBRAF (non‐Lynch). Elderly (>75 years) had more often MSI‐H (10% vs 6%) and MSI‐H/mutBRAF (9% vs 4%) tumors. Response rate (5% vs 44%), PFS (4 vs 8 months), and OS (9 vs 18 months) after first‐line chemotherapy was all significantly lower in patients with MSI‐H compared to patients with microsatellite stable tumors. MSI‐H and mutBRAF were both independent poor prognostic predictors for OS (P = 0.049, P < 0.001) and PFS (P = 0.045, P = 0.005) after first‐line chemotherapy. Patients with MSI‐H tumors received less second‐line chemotherapy (15% vs 37%, P = 0.005).

Conclusions

In unselected mCRC patients, MSI‐H and mutBRAF cases were more common than previously reported. Patients with MSI‐H tumors had worse survival, less benefit from chemotherapy, and they differed considerably from recent third‐line immunotherapy trial patients as they were older and most had mutBRAF tumor (non‐Lynch).

Salvage treatment for recurrences after first resection of colorectal liver metastases: the impact of histopathological growth patterns

The majority of patients recur after resection of colorectal liver metastases (CRLM). Patients with CRLM displaying a desmoplastic histopathological growth pattern (dHGP) have a better prognosis and lower probability of recurrence than patients with non-dHGP CRLM. The current study evaluates the impact of HGP type on the pattern and treatment of recurrences after first resection of CRLM. A retrospective cohort study was performed, including patients with known HGP type after complete resection of CRLM. All patients were treated between 2000 and 2015. The HGP was determined on the CRLM resected at first partial hepatectomy. The prognostic value of HGPs, in terms of survival outcome, in the current patient cohort were previously published. In total 690 patients were included, of which 492 (71%) developed recurrent disease. CRLM displaying dHGP were observed in 103 patients (21%). Amongst patients with dHGP CRLM diagnosed with recurrent disease, more liver-limited recurrences were seen (43% vs. 31%, p = 0.030), whereas patients with non-dHGP more often recurred at multiple locations (34% vs. 19%, p = 0.005). Patients with dHGP CRLM were more likely to undergo curatively intended local treatment for recurrent disease (adjusted odds ratio: 2.37; 95% confidence interval (CI) [1.46-3.84]; p < 0.001) compared to patients with non-dHGP. The present study demonstrates that liver-limited disease recurrence after complete resection of CRLM is more often seen in patients with dHGP, whereas patients with non-dHGP more frequently experience multi-organ recurrence. Recurrences in patients with dHGP at first CRLM resection are more likely to be salvageable by local treatment modalities, but no prognostic impact of HGPs after salvage therapy for recurrent disease was found.

Mutation status and surgical selection

Current evidence cannot support denying metastasectomy in otherwise resectable patients solely based on their overall KRAS or BRAF mutational status. The combination of KRAS or BRAF mutational status with certain clinicopathologic characteristics has defined groups of patients who may not derive benefit from metastasectomy, but external validation is needed. The effect of certain KRAS or BRAF variants on survival may be more pronounced and therefore future studies should consider them for surgical selection.

Angiogenic desmoplastic histopathological growth pattern as a prognostic marker of good outcome in patients with colorectal liver metastases

BACKGROUND

In patients with resectable colorectal liver metastases (CRLM), distinct histopathological growth patterns (HGPs) develop at the interface between the tumour and surrounding tissue. The desmoplastic (d) HGP is characterised by angiogenesis and a peripheral fibrotic rim, whereas non-angiogenic HGPs co-opt endogenous sinusoidal hepatic vasculature. Evidence from previous studies has suggested that patients with dHGP in their CRLM have improved prognosis as compared to patients with non-desmoplastic HGPs. However, these studies were relatively small and applied arbitrary cut-off values for the determination of the predominant HGP. We have now investigated the prognostic effect of dHGP in a large cohort of patients with CRLM resected either with or without neoadjuvant chemotherapy.

METHODS

All consecutive patients undergoing a first partial hepatectomy for CRLM between 2000 and 2015 at a tertiary referral centre were considered for inclusion. HGPs were assessed in archival H&E stained slides according to recently published international consensus guidelines. The dHGP was defined as desmoplastic growth being present in 100% of the interface between the tumour and surrounding liver.

RESULTS

In total, HGPs in CRLMs from 732 patients were assessed. In the chemo-naive patient cohort (n = 367), the dHGP was present in 19% (n = 68) and the non-dHGP was present in 81% (n = 299) of patients. This dHGP subgroup was independently associated with good overall survival (OS) (HR: 0.39, p < 0.001) and progression-free survival (PFS) (HR: 0.54, p = 0.001). All patients with any CRLM with a non-dHGP had significantly reduced OS compared to those patients with 100% dHGP, regardless of the proportion of non-dHGP (all p values ≤ 0.001). In the neoadjuvantly treated patient cohort (n = 365), more patients were found to express dHGP (n = 109, 30%) (adjusted odds ratio: 2.71, p < 0.001). On univariable analysis, dHGP was associated with better OS (HR 0.66, p = 0.009) and PFS (HR 0.67, p = 0.002). However, after correction for confounding by means of multivariable analysis no significant association of dHGP with OS (HR 0.92, p = 0.623) or PFS (HR 0.76, p = 0.065) was seen.

CONCLUSIONS

The current study demonstrates that the angiogenic dHGP in CRLM resected from chemo-naive patients acts as a strong, positive prognostic marker, unmatched by any other prognosticator. This observation warrants the evaluation of the clinical utility of HGPs in prospective clinical trials.

Association of Clinicopathologic and Molecular Markers on Stage-specific Survival of Right Versus Left Colon Cancer

BACKGROUND

Previous studies have shown that variability in molecular markers correlates with poorer survival outcomes in patients with right-sided colon cancer (RCC) compared with left-sided colon cancer (LCC). However, several studies have shown conflicting results when examined stage for stage. We examined RCC and LCC to assess for differences in histopathologic features and overall survival (OS).

MATERIALS AND METHODS

The National Cancer Database was used to identify patients with RCC and LCC from 2004 to 2013. A propensity-adjusted analysis evaluating the association between the primary site and OS was performed.

RESULTS

Of the 422,443 patients identified, 54.7% had RCC and 45.3% had LCC. For all stages, the patients with RCC were older, had more poorly differentiated tumors, and had a greater degree of microsatellite instability compared with those with LCC. Patients with RCC also had more KRAS mutations than did those with LCC. RCC patients had poorer 3- and 5-year OS at all stages, especially stage 3 (62% vs. 73% and 50% vs. 62%, respectively; P < .001). The median OS was 77.5 months for LCC and 62.3 months for RCC (P < .001).

CONCLUSION

The present study is one of the largest studies demonstrating that RCC and LCC are different biologic entities. Patients with RCC had significantly greater rates of microsatellite instability for all stages, which has been previously shown to be prognostically advantageous. However, the results of the present study showed poorer OS at every disease stage for RCC compared with LCC. These factors have important implications for the further use of targeted therapies in the treatment of advanced colon cancer.

Prognostic impact of KRAS and BRAF mutations in patients who underwent simultaneous resection for initially resectable colorectal liver metastases

This study aimed to explore the prognostic impact of KRAS and BRAF mutations in patients who underwent simultaneous resection for synchronous colorectal liver metastases (SCRLMs) that were initially resectable. Clinicopathological and outcome data of 139 consecutive patients with SCRLMs who underwent resection between July 2003 and July 2013 was collected from our prospectively established SCRLM database. The KRAS and BRAF genotypes were evaluated in the primary cancer tissues by pyrosequencing. The prognostic value of KRAS and BRAF status was assessed by Kaplan-Meier and Cox regression analyses. KRAS and BRAF mutated in 28.8% and 7.2% of the patients with SCRLMs, respectively, but the genotypes did not significantly associate with any clinicopathologic characteristics. By Kaplan-Meier survival analysis, we found KRAS mutation was not significantly associated with short overall survival (OS) (P = 0.213), but was significantly correlated with short disease-free survival (DFS) (P = 0.041); BRAF mutation was significantly associated with both short OS and DFS (P = 0.001, P<0.001, respectively). Multivariate survival analysis showed KRAS mutation was an independent negative prognostic factor for DFS (P = 0.005) and BRAF mutation was an independent negative prognostic factor for OS and DFS (P = 0.001, P<0.001, respectively). KRAS and BRAF mutation similarly contributed to an adverse prognostic effect in patients who underwent simultaneous resection for SCRLMs that were initially resectable. These findings should suggest the use of KRAS and BRAF status in current practice as an important determinant for precision surgery for initially resectable SCRLMs.

Prognostic value of the combination of microsatellite instability and BRAF mutation in colorectal cancer

Purpose

The aim of this study was to investigate the prognostic value of the combination of microsatellite instability (MSI) and BRAF V600E mutation in colorectal cancer (CRC).

Materials and methods

We compare the prognosis difference among CRC patients with four subtypes according to MSI and BRAF mutation, ie, microsatellite stable/BRAF wild type (MSS/BRAFwt), MSS/BRAF mutation (MSS/BRAFmut), MSI/BRAFwt, and MSI/BRAFmut, by pooling the previous related reports and public available data sets till December 2017 for the first time.

Results

Twenty-seven independent studies comprising 24,067 CRC patients were included. Meta-analysis suggested that, compared with MSS/BRAFwt subtype, MSS/BRAFmut was associated with shorter overall survival (OS) (N=25, HR = 2.018, 95% CI = 1.706-2.388, P=2.220E-16), while there was a trend of association of MSI/BRAFmut with OS (N=13, HR = 1.324, 95% CI = 0.938-1.868, P=1.096E-01) and no association of MSI/BRAFwt with OS (N=17, HR = 0.996, 95% CI = 0.801-1.240, P=9.761E-01). Compared with MSI/ BRAFwt subtype, MSI/BRAFmut was a poor factor for OS (N=22, HR = 1.470, 95% CI = 1.243-1.740, P=7.122E-06). Compared with MSS/BRAFmut subtype, both MSI/BRAFwt (N=11, HR = 0.560, 95% CI = 0.433-0.725, P=1.034E-05) and MSI/BRAFmut (N=16, HR = 0.741, 95% CI = 0.567-0.968, P=2.781E-02) were favorable for OS. Subgroup analysis revealed similar results in all subgroups except the subgroup of stage IV cancer, in which MSI showed poor effects on OS in BRAF wild-type patients (N=6, HR = 1.493, 95% CI = 1.187-1.879, P=6.262E-04) but not in BRAF-mutated patients (N=5, HR = 1.143, 95% CI = 0.789-1.655, P=4.839E-01). Meta-analysis regression and test of interaction revealed no interaction of MSI with BRAF mutation when evaluating the associations of MSI/BRAF mutation subtypes with OS in CRC.

Conclusion

Among the four subtypes according to MSI and BRAF mutation, MSS/BRAFmut was a poor prognostic factor, while MSS/BRAFwt and MSI/BRAFwt were comparable and favorable and MSI/BRAFmut was moderate in CRC. The combination of MSI/BRAF mutations could facilitate the planning of individualized treatment strategies and prognosis improvement in CRC.

BRAF mutant colorectal cancer: prognosis, treatment, and new perspectives

The MAPK cascade plays a crucial role in tumor cell proliferation and survival. Accumulating evidence suggests that mutations in the BRAF oncogene are not only associated with poor prognosis but also linked with less benefit when treated with anti-epidermal growth factor receptor antibodies in metastatic colorectal cancer (mCRC). Targeting this molecular aberration has thus become a matter of particular interest in mCRC drug development. In contrast to other malignances such as BRAF mutant melanoma, efficacy observed with BRAF inhibitors in monotherapy in mCRC is poor. Several mechanisms of resistance have been identified leading to the development of different treatment strategies that have shown promising activity in early clinical trials. Hence, rational combination of targeted therapies is expected to further increase the efficacy of selective BRAF inhibitors. Herein, we discuss the main clinical and molecular characteristics of BRAF mutant colorectal cancer and its translation into the clinic, with a focus on developmental therapeutics and combination strategies. In addition, we contextualize the available data with potential future approaches that include the extended access to next-generation sequencing platforms and gene expression strategies for molecular subtyping. These approaches will facilitate the identification of certain patient profiles providing more therapeutic possibilities.

Incorporating Biomarker Stratification into STAMPEDE: an Adaptive Multi-arm, Multi-stage Trial Platform

The treatment and outcomes for advanced prostate cancer have experienced significant progress over recent years. Importantly, the additional benefits of ‘up front’ chemotherapy (docetaxel) and abiraterone, over and above conventional androgen deprivation, have been separately demonstrated in the multi-arm, multi-stage (MAMS) STAMPEDE protocol, which continues recruitment to other questions. Alongside this, insights into the underlying molecular biology and, inevitably, the molecular heterogeneity of prostate cancer are opening the door to new therapeutic approaches. Incorporating this understanding and testing these hypotheses within STAMPEDE brings new challenges to the MAMS approach, but has the potential to further improve the outlook for this disease.

BRAF Mutations as Predictive Biomarker for Response to Anti-EGFR Monoclonal Antibodies

Recently, the American Society of Clinical Oncology (ASCO) and the European Society for Medical Oncology (ESMO) recommended that patients with epidermal growth factor receptor (EGFR)-expressing metastatic colorectal cancer could be treated with anti-EGFR monoclonal antibodies (mAbs) cetuximab and panitumumab only in absence of Rat-Sarcoma (RAS) mutations. In addition to the previously established biomarker Kirsten rat sarcoma viral oncogene homolog (KRAS) exon 2, cumulative evidence also shows that patients whose tumors harbor KRAS exons 3 or 4 and neuroblastoma rat-sarcoma viral oncogene homolog (NRAS) exons 2, 3, and 4 mutations are found unlikely to benefit from anti-EGFR treatment.In line with the resistance of RAS mutated (mt) tumors, treatment response in BRAFmt tumors may also be altered given their important role in the EGFR signaling pathway. However, BRAF is not recommended as predictive biomarker yet because the evidence for the impact of BRAF mutations on treatment outcome is considered insufficient.This article summarizes the evidence for the impact of BRAF mutations on treatment outcome of anti-EGFR mAbs. Based on a review of literature, eight meta-analyses were included that consistently show that patients with BRAF mutations have a lack of treatment benefit of anti-EGFR mAbs. After discussing the quality and quantity of available evidence, we conclude that evidence is stronger than suggested by ESMO and ASCO. Additionally, we highlight that the quality of evidence for BRAF is even higher than for extended RAS as a biomarker. We therefore advise ESMO and ASCO to reconsider BRAF status as a predictive biomarker for response.

IMPLICATIONS FOR PRACTICE

In metastatic colorectal cancer (mCRC), therapy with anti-epidermal growth factor receptor (EGFR) monoclonal antibodies cetuximab and panitumumab is indicated in absence of RAS mutations. Cumulative evidence shows that patients with BRAF mutations, who comprise 10% of the mCRC population, do not benefit from anti-EGFR-antibody treatment. Although guidelines state that evidence for BRAF as a predictive marker is insufficient, we highlight that the quality and quantity of evidence is higher than suggested. We therefore encourage the use of BRAF as a predictive marker in order to exclude patients from therapy for whom limited treatment benefit is expected.

Investigating the poor outcomes of BRAF-mutant advanced colorectal cancer: analysis from 2530 patients in randomised clinical trials

Background

To improve strategies for the treatment of BRAF-mutant advanced colorectal cancer (aCRC) patients, we examined individual data from patients treated with chemotherapy alone in three randomised trials to identify points on the treatment pathway where outcomes differ from BRAF wild-types.

Patients and methods

2530 aCRC patients were assessed from three randomised trials. End-points were progression-free survival, response rate, disease control rate, post-progression survival (P-PS) and overall survival. Treatments included first-line oxaliplatin/fluorouracil (OxFU) and second-line irinotecan. Clinicians were unaware of BRAF-status.

Results

231 patients (9.1%) had BRAF-mutant tumours. BRAF-mutation conferred significantly worse survival independent of associated clinicopathological factors known to be prognostic. Compared with wild-type, BRAF-mutant patients treated with first-line OxFU had similar DCR (59.2% versus 72%; adjusted OR = 0.76, P = 0.24) and PFS (5.7 versus 6.3 months; adjusted HR = 1.14, P = 0.26). Following progression on first-line chemotherapy, BRAF-mutant patients had a markedly shorter P-PS (4.2 versus 9.2 months, adjusted HR = 1.69, P < 0.001). Fewer BRAF-mutant patients received second-line treatment (33% versus 51%, P < 0.001), but BRAF-mutation was not associated with inferior second-line outcomes (RR adjusted OR = 0.56, P = 0.45; PFS adjusted HR = 1.01, P = 0.93). Significant clinical heterogeneity within the BRAF-mutant population was observed: a proportion (24.3%) had good first-line PFS and P-PS (both >6 months; OS = 24.0 months); however, 36.5% progressed rapidly through first-line chemotherapy and thereafter, with OS = 4.7 months.

Conclusions

BRAF-mutant aCRC confers a markedly worse prognosis independent of associated clinicopathological features. Chemotherapy provides meaningful improvements in outcome throughout treatment lines. Post-progression survival is markedly worse and vigilance is required to ensure appropriate delivery of treatment after first-line progression.

Primary tumor site and anti-EGFR monoclonal antibody benefit in metastatic colorectal cancer: a meta-analysis

AIM

This meta-analysis aimed to document the impact of primary tumor site on anti-EGFR monoclonal antibody (mAb) benefit in metastatic colorectal cancer.

MATERIALS & METHODS

Tumors with metastatic left-sided colorectal cancer (LCC) were compared with tumors with metastatic right-sided colon cancer (RCC) with respect to anti-EGFR mAb objective response rate (ORR), overall survival (OS) and progression-free survival (PFS) benefit.

RESULTS

Comparing LCC with RCC, LCC was found to have significantly superior anti-EGFR mAb ORR (p < 0.00001), OS (p < 0.00001) and PFS (p < 0.00001) benefit. Additionally, anti-EGFR mAb therapy significantly improved both OS and PFS for LCC compared with no anti-EGFR mAb therapy, but not for RCC. The test of interaction was also apparent for OS (p = 0.0002) and PFS (p = 0.0002).

CONCLUSION

This meta-analysis demonstrated that LCC had markedly superior anti-EGFR mAb treatment benefit compared with RCC.

Molecular spectrum of KRAS, NRAS, BRAF, PIK3CA, TP53, and APC somatic gene mutations in Arab patients with colorectal cancer: determination of frequency and distribution pattern

BACKGROUND

The frequency rates of mutations such as KRAS, NRAS, BRAF, and PIK3CA in colorectal cancer (CRC) differ among populations. The aim of this study was to assess mutation frequencies in the Arab population and determine their correlations with certain clinicopathological features.

METHODS

Arab patients from the Arab Gulf region and a population of age- and sex-matched Western patients with CRC whose tumors were evaluated with next-generation sequencing (NGS) were identified and retrospectively reviewed. The mutation rates of KRAS, NRAS, BRAF, PIK3CA, TP53, and APC were recorded, along with clinicopathological features. Other somatic mutation and their rates were also identified. Fisher's exact test was used to determine the association between mutation status and clinical features.

RESULTS

A total of 198 cases were identified; 99 Arab patients and 99 Western patients. Fifty-two point seven percent of Arab patients had stage IV disease at initial presentation, 74.2% had left-sided tumors. Eighty-nine point two percent had tubular adenocarcinoma and 10.8% had mucinous adenocarcinoma. The prevalence rates of KRAS, NRAS, BRAF, PIK3CA, TP53, APC, SMAD, FBXW7 mutations in Arab population were 44.4%, 4%, 4%, 13.1%, 52.5%, 27.3%, 2% and 3% respectively. Compared to 48.4%, 4%, 4%, 12.1%, 47.5%, 24.2%, 11.1% and 0% respectively in matched Western population. Associations between these mutations and patient clinicopathological features were not statistically significant.

CONCLUSIONS

This is the first study to report comprehensive hotspot mutations using NGS in Arab patients with CRC. The frequency of KRAS, NRAS, BRAF, TP53, APC and PIK3CA mutations were similar to reported frequencies in Western population except SMAD4 that had a lower frequency and higher frequency of FBXW7 mutation.

BRAF and NRAS Locus-Specific Variants Have Different Outcomes on Survival to Colorectal Cancer

Purpose: Somatic mutation status at KRAS, BRAF, and NRAS is associated with prognosis in patients with advanced colorectal cancer (aCRC); however, it remains unclear whether there are intralocus, variant-specific differences in survival and other clinicopathologic parameters.Experimental Design: We profiled 2,157 aCRCs for somatic mutations in KRAS, BRAF, and NRAS and determined microsatellite instability status. We sought inter- and intralocus correlations between mutations and variant-specific associations with survival and clinicopathology.Results:KRAS mutations were rarely found together and those in codons 12 and 13 conferred poor prognosis [hazard ratio (HR), 1.44; 95% confidence interval (CI), 1.28-1.61; P = 6.4 × 10^-10 and HR, 1.53; 95% CI, 1.26-1.86; P = 1.5 × 10^-05, respectively]. For BRAF, more c.1781A>G (p.D594G) CRCs carried RAS mutations [14% (3/21)] compared with c.1799T>A (p.V600E) CRCs [1% (2/178), P = 9.0 × 10^-03]. c.1799T>A (p.V600E) was associated with poor prognosis (HR, 2.60; 95% CI, 2.06-3.28; P = 1.0 × 10^-15), whereas c.1781A>G (p.D594G) was not (HR, 1.30; 95% CI, 0.73-2.31; P = 0.37); this intralocus difference was significant (P = 0.04). More c.1799T>A (p.V600E) colorectal cancers were found in the right colon [47% (47/100)], compared with c.1781A>G (p.D594G) colorectal cancers [7% (1/15), P = 3.7 × 10^-03]. For NRAS, 5% (3/60) of codon 61 mutant colorectal cancers had KRAS mutations compared with 44% (10/23) of codons 12 and 13 mutant colorectal cancers (P = 7.9 × 10^-05). Codon 61 mutations conferred poor prognosis (HR, 1.47; 95% CI, 1.09-1.99; P = 0.01), whereas codons 12 and 13 mutations did not (HR, 1.29; 95% CI, 0.64-2.58; P = 0.48).Conclusions: Our data show considerable intralocus variation in the outcomes of mutations in BRAF and NRAS These data need to be considered in patient management and personalized cancer therapy. Clin Cancer Res; 23(11); 2742-9. ©2016 AACR.

New Therapeutic Opportunities Based on DNA Mismatch Repair and BRAF Status in Metastatic Colorectal Cancer

Recently, colorectal cancer (CRC) subtyping consortium identified four consensus molecular subtypes (CMS1-4). CMS1 is enriched for deficient mismatch repair (dMMR) and BRAF (V600E) tumors. Intriguingly, this subtype has better relapse-free survival but worse overall survival after relapse compared with the other subtypes. Growing evidence is accumulating on the benefit of specific therapeutic strategies such as immune checkpoint inhibition therapy in dMMR tumors and mitogen-activated protein kinase (MAPK) pathway targeted therapy in tumors harboring BRAF (V600E) mutation. After reviewing dMMR prognostic value, immune checkpoints as major targets for dMMR carcinomas will be highlighted. Following, BRAF (V600E) prognostic impact will be reviewed and therapeutic strategies with the combination of cytotoxic agents and especially the combinations of BRAF and MAPK inhibitors will be discussed.

Molecular pathological epidemiology of colorectal cancer in Chinese patients with KRAS and BRAF mutations

An investigation of interactive effects of exogenous and endogenous factors and tumor molecular changes can lead to a better understanding of tumor molecular signatures in colorectal cancer. We here report a molecular pathological epidemiology study in a large cohort of 945 colorectal cancer patients. Mutations of KRAS (36.6%) and BRAF (3.46%) were nearly mutually exclusive. KRAS-mutated tumors were more common in female patients (odds ratio [OR] = 1.68; P = 0.0001) and never smokers (OR = 1.60; P = 0.001). Whereas BRAF-mutated tumors demonstrated no discrepancy in aspects of gender and smoking status compared with wild-type tumors. In addition, tumors with BRAF or KRAS mutations were in correlation with elevated serum level of carbohydrate antigen (CA19-9) and carcinoma embryonic antigen (CEA) and the combination of serum biomarkers and molecular mutation status may enhance the more precise risk stratification of CRC patients. Further studies are needed to define the mechanism brought about by the aforementioned epidemiologic and clinicopathologic characteristics that may help optimize cancer prevention and precision therapy.

Role of targeted therapy in metastatic colorectal cancer

Colorectal cancer (CRC) is a significant cause of cancer-related morbidity and mortality all over the world. Improvements of cytotoxic and biologic agents have prolonged the survival in metastatic CRC (mCRC), with a median overall survival of approximately 2 years and more in the past two decades. The biologic agents that have proven clinical benefits in mCRC mainly target vascular endothelial growth factor (VEGF) and epidermal growth factor receptor (EGFR). In particular, bevacizumab targeting VEGF and cetuximab and panitumumab targeting EGFR have demonstrated significant survival benefits in combination with cytotoxic chemotherapy in the first-line, second-line, or salvage setting. Aflibercept, ramucirumab, and regorafenib are also used in second-line or salvage therapy. Recent retrospective analyses have shown that KRAS or NRAS mutations were negative predictive markers for anti-EGFR therapy. Based on the evidence from large randomized clinical trials, personalized therapy is necessary for patients with mCRC according to their tumor biology and characteristics. The aim of this paper was to summarize the results of the major randomized clinical trials and highlight the benefits of the molecular targeted agents in patients with mCRC.

Differences in prognosis and molecular biological features between left- and right-sided colon cancer

Apart from differences in epidemiologic, pathologic and symptomatic features, the natural prognosis, therapeutic prognosis, as well as survival after relapse also show great differences between left- and right-sided colon cancer. Those differences in prognosis are noticed to be dependent on tumor stage and also thought to be due to the variant genetic background and molecular biological features. In this review, we summarize the differences in prognosis and molecular biological features between left- and right-sided colon cancer, and discuss the possible connections between clinical and molecular differences. Taking into account the impact that location and differentially expressed molecules may have on prognosis, clinicians could have a more accurate estimate on the prognosis of colon cancer patients.