KRAS, NRAS and BRAF analysis of ampullary adenocarcinoma classified using CK7, CK20, MUC1 and MUC2

Ampullary Adenocarcinoma: A Review of the Mutational Landscape and Implications for Treatment

Ampullary carcinomas represent less than 1% of all gastrointestinal malignancies with an incidence of approximately 6 cases per 1 million. Histologic examination and immunohistochemistry have been traditionally used to categorize ampullary tumors into intestinal, pancreatobiliary or mixed subtypes. Intestinal-subtype tumors may exhibit improved survival versus the pancreatobiliary subtype, although studies on the prognostic value of immunomorphologic classification have been inconsistent. Genomic classifiers hold the promise of greater reliability, while providing potential targets for precision oncology. Multi-institutional collaboration will be necessary to better understand how molecular classification can guide type and sequencing of multimodality therapy.

Nab-Paclitaxel and Gemcitabine as First-Line Treatment of Metastatic Ampullary Adenocarcinoma with a Novel R-Spondin2 RNA Fusion and NTRK3 Mutation

Ampullary adenocarcinoma is a rare malignancy that lacks standard systemic treatment. We describe a case of recurrent metastatic ampullary adenocarcinoma of the pancreaticobiliary subtype treated with nanoparticle albumin-bound (nab)-paclitaxel and gemcitabine as first-line treatment. This report also highlights the molecular profile of the ampullary adenocarcinoma and circulating tumor DNA (ctDNA). This is a case of pancreaticobiliary ampullary adenocarcinoma in a 67-year-old woman who initially presented with painless jaundice. Endoscopic and imaging evaluation revealed biliary ductal dilation secondary to an ampullary mass. Pathology confirmed the diagnosis of ampullary adenocarcinoma of the pancreaticobiliary subtype. She underwent surgical resection of the tumor, followed by adjuvant chemotherapy with gemcitabine and capecitabine. The tumor subsequently recurred in the liver. She received palliative chemotherapy with nab-paclitaxel and gemcitabine, resulting in an objective tumor response for 14 months. Molecular profiling of the tumor and ctDNA revealed a novel MATN2-RSPO RNA fusion and a novel NTRK3 mutation, respectively. Our report suggests that long-term durable response can be achieved in metastatic pancreaticobiliary ampullary adenocarcinoma using nab-paclitaxel and gemcitabine. Molecular profiling of the tumor identified a novel R-Spondin2 RNA fusion and NTRK3 mutation that can be potentially targeted for treatment.

Molecular pathways in periampullary cancer: An overview

Molecular alterations in oncogenes and tumor suppressors in various signaling pathways are basis for personalized therapy in cancer. Periampullary carcinoma behaves differently from pancreatic carcinoma both in prognosis and outcome, therefore it needs special attention. Pancreatic cancer have higher incidence of nodal spread and perineural &lymphovascular invasion suggesting it biologically more aggressive tumor compared to periampullary cancer. Since PAC tumors consist of heterogenous tissue of origin, they might contain different mutations in tumor associated genes and other changes in tissue composition among different subgroups clubbed together. Significant progress has been made in understanding the molecular nature of PAC in the previous two decades, and a large number of mutations and other genetic changes have been identified as being responsible for the disease. This review article targets to collate and discuss the molecular evolution of PAC and their implication in its outcome. As per literature, mitogen-activated protein kinase (MAPK), phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K), and Wnt signaling are the most common pathways involved in PAC. Mutations in KRAS, TP53, CTNNB1, SMAD4 and APC genes were the most frequently reported. I-subtype resembles colorectal cancer while the morphology of PB-type shows close resemblance to pancreatic tumors. The frequency of driver gene mutations is higher in I-type compared to PB-type of PAC indicating I-type to be genetically more unstable. The genetic landscape of PAC obtained from WES data highlighted PI3/AKT pathway to be a primary target in I-type and RAS/RAF in PB-type.

USP8, USP48, and BRAF mutations differ in their genotype-phenotype correlation in Asian Indian patients with Cushing's disease

PURPOSE

To estimate the prevalence of USP8, USP48, and BRAF mutations in patients with Cushing's disease (CD) from the Indian subcontinent, and determine their genotype-phenotype correlation.

METHODS

We prospectively recruited 46 patients with CD who underwent surgery between September 2015 and July 2019 at our institute. Fresh frozen tumour tissue was obtained in all patients. Using Sanger sequencing, the presence of somatic USP8 mutations was documented and the frequency of USP48 and BRAF mutations in USP8 wild-type corticotroph adenomas was determined. Clinical, hormonal, and surgical data were then compared between USP8-, USP48- and BRAF-variant carriers and patients with wild-type tumours.

RESULTS

Signature USP8 mutations were detected in 17 (37%) patients. Of the 29 USP8 wild-type adenomas, 4 (13.8%) harboured USP48 mutations, one of them being a splice-site mutation that has previously not been described. BRAF mutations were not found in any of the 29 patients. Corticotroph adenomas with USP8 mutations had a higher incidence of Crooke's hyaline change than wild-type tumours (70.6 vs. 37.9%, p = 0.032). Adenomas with USP48 mutations had a higher rate of cavernous sinus invasion than their wild-type counterparts (50 vs. 4%, p = 0.042). No other significant phenotypic difference could be established between mutant and wild-type tumours.

CONCLUSIONS

The prevalence of USP8 mutations in our series of patients with CD was 37%. The prevalence of USP48 mutations in USP8 wild-type adenomas was 13.8%, including a novel splice-site mutation. BRAF mutations were not found in any USP8 wild-type tumour. USP8-mutants showed significantly more Crooke's hyaline change and USP48-mutants were more likely to demonstrate cavernous sinus invasion.

Ampullary and pancreatic adenocarcinoma-a comparative study

Background

Pancreatic ductal adenocarcinoma (PDAC) and ampullary adenocarcinoma (AAC) are 2 gastrointestinal cancers that share overlapping symptoms. Although some studies have proposed the hypothesis of differences in pathogenesis and prognosis in these 2 cancers; they remain treated similarly. The classification of AAC into three subtypes [pancreatobiliary (PB), intestinal (IT) and mixed (M)] is especially crucial for the 3 axes of patients management (diagnosis, prognosis and therapy). Some studies suggest that PB subtype pathogenesis is comparable to PDAC. The objective of this study was to conduct a comparative analysis between PDAC and AAC; notably PB subtype; via mutational status analysis of 3 oncogenes (KRAS, NRAS and BRAF) hoping to consolidate AAC biology understanding.

Methods

Nine hot spot mutation sites of KRAS, NRAS and BRAF were analysed using pyrosequencing in 39 PDAC and 21 AAC from Tunisian patients. Comparative study was performed using SPSS software.

Results

Mutations in oncogenes were detected in almost 43% of AAC, especially in PB (47%) and 95% of PDAC. KRAS was the most mutated oncogene. There were statistical significant differences between PDAC and AAC in tumor differentiation (P<0.001), perineural invasion (P<0.001), vascular emboli (P=0.001), T stage (P=0.007), N stage (P=0.001) and mutational status (P<0.001). When comparing PDAC and PB subtype, there were also significant differences in tumor size (P=0.001), tumor differentiation (P<0.001), perineural invasion (P<0.001), vascular emboli (P=0.001), T stage (P=0.033), N stage (P<0.001) and mutational status (P<0.001).

Conclusions

AAC even PB subtype is different from PDAC. We think that these different tumor types require highly individualized therapy guided by their histomolecular characteristics and that we should stop diagnosing and treating them as a unique entity.