BRAF p.V600E-specific immunohistochemical assessment in colorectal cancer endoscopy biopsies is consistent with the mutational profiling

BRAF-mutated colorectal adenocarcinomas: pathological heterogeneity and clinical implications

Advances in molecular biology have markedly increased our understanding of the heterogeneous molecular landscape of colorectal cancer (CRC). Up to 15% of CRCs harbor the BRAF p.V600E somatic mutation (BRAFmt), a well-established negative prognostic marker in patients with metastatic CRC (mCRC). The BEACON CRC trial set a new standard of care in patients with progressive BRAFmt cancers, consisting of the combination of encorafenib and cetuximab. On these bases, BRAF mutational testing is now recommended in patients with mCRC. However, efforts are needed to further stratify patients carrying this mutation. Here, we discuss the heterogeneous pathologic and molecular landscape of BRAFmt CRCs, focusing on the promises and pitfalls of molecular diagnostics, on novel biomarkers to improve patients' stratification and on the current diagnostic scenario for CRC. We believe that a better stratification based on histopathological features and novel molecular biomarkers should be performed to optimize patient management and therapeutic decision-making.

Current prognostic and predictive biomarkers for gastrointestinal tumors in clinical practice

The pathologist emerged in the personalized medicine era as a central actor in the definition of the most adequate diagnostic and therapeutic algorithms. In the last decade, gastrointestinal oncology has seen a significantly increased clinical request for the integration of novel prognostic and predictive biomarkers in histopathological reports. This request couples with the significant contraction of invasive sampling of the disease, thus conferring to the pathologist the role of governor for both proper pathologic characterization and customized processing of the biospecimens. This overview will focus on the most commonly adopted immunohistochemical and molecular biomarkers in the routine clinical characterization of gastrointestinal neoplasms referring to the most recent published recommendations, guidelines and expert opinions.

Tumor Mutational Burden as a Potential Biomarker for Immunotherapy in Pancreatic Cancer: Systematic Review and Still-Open Questions

Simple Summary

Tumor mutational burden (TMB) represents the number of mutations per megabase (muts/Mb) harbored by tumor cells in a given neoplasm, and can be determined with next-generation sequencing. High values are an indicator of potential response to immunotherapy. With this systematic review, we assessed its role in pancreatic ductal adenocarcinoma (PDAC). Our main findings can be summarized as: (i) high-TMB can be found in about 1% of PDAC; (ii) it is associated with mucinous/colloid and medullary histology; (iii) high-TMB PDAC frequently harbor other actionable alterations, with microsatellite instability as the most common; (iv) immunotherapy has shown promising results in high-TMB PDAC.

Abstract

Tumor mutational burden (TMB) is a numeric index that expresses the number of mutations per megabase (muts/Mb) harbored by tumor cells in a neoplasm. TMB can be determined using different approaches based on next-generation sequencing. In the case of high values, it indicates a potential response to immunotherapy. In this systematic review, we assessed the potential predictive role of high-TMB in pancreatic ductal adenocarcinoma (PDAC), as well as the histo-molecular features of high-TMB PDAC. High-TMB appeared as a rare but not-negligible molecular feature in PDAC, being present in about 1.1% of cases. This genetic condition was closely associated with mucinous/colloid and medullary histology (p < 0.01). PDAC with high-TMB frequently harbored other actionable alterations, with microsatellite instability/defective mismatch repair as the most common. Immunotherapy has shown promising results in high-TMB PDAC, but the sample size of high-TMB PDAC treated so far is quite small. This study highlights interesting peculiarities of PDAC harboring high-TMB and may represent a reliable starting point for the assessment of TMB in the clinical management of patients affected by pancreatic cancer.

Colorectal cancer with microsatellite instability: Right-sided location and signet ring cell histology are associated with nodal metastases, and extranodal extension influences disease-free survival

Colorectal cancer (CRC) with microsatellite instability (MSI) accounts for 15-18 % of all CRCs and represents the category with the best prognosis. This study aimed at determining any possible clinical/pathological features associated with a higher risk of nodal metastasization in MSI-CRC, and at defining any possible prognostic moderators in this setting. All surgically resected CRCs of the last 20 years (mono-institutional series) with a PCR-based diagnosis of MSI, with and without nodal metastasis, have been retrieved for histological review, which was performed following WHO guidelines. Furthermore, the most important prognostic moderators have been investigated with a survival analysis. The study of 33 cases of MSI-CRCs with nodal metastasis highlighted a high fidelity of histology maintenance between primary tumors and matched nodal metastases. At survival analysis, the strongest prognostic variable in MSI-CRCs with nodal metastasis was the extranodal extension (multivariate analysis, HR: 14.4, 95 %CI: 1.46-140.9, p = 0.022). Furthermore, through a comparison between nodal positive (33 cases) and nodal negative (71 cases) MSI-CRCs, right-sided location (p < 0.0001), pT4 stage (p = 0.0004) and signet-ring histology (p = 0.0089) emerged as parameters more commonly associated with nodal metastasization. These findings shed new light on the biology of MSI-CRC and can be of help for the prognostic stratification of MSI-CRC patients.

The heterogeneous clinical and pathological landscapes of metastatic Braf-mutated colorectal cancer

Colorectal cancer (CRC) is a complex and molecularly heterogeneous disease representing one of the most frequent causes of cancer-related death worldwide. About 8–15% of CRCs harbor a mutation in BRAF gene, a proto-oncogene involved in cell proliferation, differentiation and survival through the MAPK signaling cascade. The acquisition of BRAF mutation is an early event in the “serrated” CRC carcinogenetic pathway and is associated with specific and aggressive clinico-pathological and molecular features. Despite that the presence of BRAF mutation is a well-recognized negative prognostic biomarker in metastatic CRC (mCRC), a great heterogeneity in survival outcome characterizes these patients, due to the complex, and still not completely fully elucidated, interactions between the clinical, genetic and epigenetic landscape of BRAF mutations. Because of the great aggressiveness of BRAF-mutated mCRCs, only 60% of patients can receive a second-line chemotherapy; so intensive combined and tailored first-line approach could be a potentially effective strategy, but to minimize the selective pressure of resistant clones and to reduce side effects, a better stratification of patients bearing BRAF mutations is needed.

Current Tissue Molecular Markers in Colorectal Cancer: A Literature Review

BACKGROUND

Colorectal cancer (CRC) is one of the most spread neoplasia types all around the world, especially in western areas. It evolves from precancerous lesions and adenomatous polyps, through successive genetic and epigenetic mutations. Numerous risk factors intervene in its development and they are either environmental or genetic.

AIM OF THE REVIEW

Alongside common screening techniques, such as fecal screening tests, endoscopic evaluation, and CT-colonography, we have identified the most important and useful biomarkers and we have analyzed their role in the diagnosis, prevention, and prognosis of CRC.

CONCLUSION

Biomarkers can become an important tool in the diagnostic and therapeutic process for CRC. But further studies are needed to identify a noninvasive, cost-effective, and highly sensible and specific screening test for their detection and to standardize their use in clinical practice.