The Italian Rare Pancreatic Exocrine Cancer Initiative

Clinical and Genomic Characterization of Pancreatic Ductal Adenocarcinoma with Signet-Ring/Poorly Cohesive Cells

Signet-ring cell (SRC)/poorly cohesive cell carcinoma is an aggressive variant of pancreatic ductal adenocarcinoma (PDAC). This study aimed to clarify its clinicopathologic and molecular profiles based on a multi-institutional cohort of 20 cases. The molecular profiles were investigated using DNA and RNA sequencing. The clinicopathologic parameters and molecular alterations were analyzed based on survival indices and using a validation/comparative cohort of 480 conventional PDAC patients. The primary findings were as follows: (1) clinicopathologic features: SRC carcinomas are highly aggressive neoplasms with poor prognosis, and the lungs are elective metastatic sites; (2) survival analysis: a higher SRC component was indicative of poorer prognosis. In particular, the most clinically significant threshold of SRC was 80%, showing statistically significant differences in both disease-specific and disease-free survival; (3) genomic profiles: SRC carcinomas are similar to conventional PDAC with the most common alterations affecting the classic PDAC drivers KRAS (70% of cases), TP53 (55%), SMAD4 (25%), and CDKN2A (20%). EGFR alterations, RET::CCDC6 fusion gene, and microsatellite instability (3 different cases, 1 alteration per case) represent novel targets for precision oncology. The occurrence of SMAD4 mutations was associated with poorer prognosis; (4) pancreatic SRC carcinomas are genetically different from gastric SRC carcinomas: CDH1, the classic driver gene of gastric SRC carcinoma, is not altered in pancreatic SRC carcinoma; (5) transcriptome analysis: the cases clustered into 2 groups, one classical/exocrine-like, and the other squamous-like; and (6) SRC carcinoma-derived organoids can be successfully generated, and their cultures preserve the histologic and molecular features of parental SRC carcinoma. Although pancreatic SRC carcinoma shares similarities with conventional PDAC regarding the most important genetic drivers, it also exhibits important differences. A personalized approach for patients with this tumor type should consider the clinical relevance of histologic determination of the SRC component and the presence of potentially actionable molecular targets.

Pancreatic Adenosquamous Carcinoma: A Rare Pathological Subtype of Pancreatic Cancer

Pancreatic adenosquamous carcinoma (PASC) is a rare pathological subtype of pancreatic cancer (PC), with a worse prognosis than pancreatic ductal adenocarcinoma (PDAC). Due to its rarity, our knowledge of PASC and its biological characteristics are limited. In this review, we provide an overview of the histogenesis, genetic features, diagnosis, treatment, and prognosis of PASC, as well as pancreatic squamous cell carcinoma (PSCC). The information provided here may help to clarify our understanding of PASC and provide useful avenues for further research on this disease.

Genomic characterization of undifferentiated sarcomatoid carcinoma of the pancreas

Undifferentiated sarcomatoid carcinoma (USC) of the pancreas is a rare but especially aggressive variant of pancreatic ductal adenocarcinoma (PDAC), composed of at least 80% of sarcomatoid cells. This study aimed to elucidate its clinicopathological and molecular features. The study cohort included 10 patients with pancreatic USC. Clinicopathological parameters were determined for each patient. The molecular profile was investigated using next-generation sequencing (NGS). Histologically, all tumors were hypercellular neoplasms with spindle-shaped or sarcomatoid cells. All patients showed vascular and perineural invasion. Most patients had a poor prognosis. NGS showed important similarities with conventional PDAC, including frequent alterations in the classic PDAC drivers, KRAS (100% of cases), TP53 (90%), and CDKN2A (60%). There were also some important distinctions from conventional PDAC: 1) SMAD4, a typical PDAC driver gene, was mutated in only one case (10%); 2) Another distinctive molecular feature was the recurrent KRAS amplification (30% of cases), which is very rare in conventional PDAC. It has been previously reported in another subtype of pancreatic undifferentiated carcinoma, the rhabdoid variant, and may be a key event leading to the acquisition of an undifferentiated phenotype in a subgroup of cases; 3) Lastly, in two different cases, we detected two potentially actionable targets, not belonging to the typical PDAC molecular landscape, such as MCL1 amplification and POLQ mutation. Our study sheds light on this rare tumor type, which shows aggressive biological behavior and few druggable alterations. The most distinctive molecular features of pancreatic USC are the paucity of SMAD4 alterations and recurrent KRAS amplification.

BRCA-mutant pancreatic ductal adenocarcinoma

Despite continued research, pancreatic ductal adenocarcinoma (PDAC) remains one of the main causes of cancer death. Interest is growing in the role of the tumour suppressors breast cancer 1 (BRCA1) and BRCA2-typically associated with breast and ovarian cancer-in the pathogenesis of PDAC. Indeed, both germline and sporadic mutations in BRCA1/2 have been found to play a role in the development of PDAC. However, data regarding BRCA1/2-mutant PDAC are lacking. In this review, we aim to outline the specific landscape of BRCA-mutant PDAC, focusing on heritability, clinical features, differences between BRCA1 and 2 mutations and between germline and sporadic alterations, as well as established therapeutic strategies and those that are still under evaluation.

PD-L1 and Notch as novel biomarkers in pancreatic sarcomatoid carcinoma: a pilot study

BACKGROUND

The improved immunological understanding revealed the tumor microenvironment as an appealing driver to restore the immune response against cancer cells resulting in a paradigm shift in the oncology field. However, the complexity of the tumor milieu suggests the role of several pathways linking in immunomodulation mechanisms. Pancreatic cancer represents a model of the intricate relationship between malignant cells and their surrounding neighborhood.

RESEARCH DESIGN AND METHODS

In this study, we analyzed, retrospectively, six cases of rare pancreatic sarcomatoid carcinoma (PSC) and evaluated the expression of PD-L1 and Notch, aiming to explore new attributes in immunophenotype.

RESULTS

PD-L1 CPS ≥ 1was common in PSCs (83%) with half samples expressing PD-L1 CPS ≥ 50. Notch1 and Notch3 demonstrated a high range of expression. A direct significant correlation between PD-L1 and Notch3 overexpression (r = 0.7; p = 0.036) has been observed. Immunofluorescence studies revealed a co-localization of Notch3 and PD-L1 when both proteins were over-expressed within cytoplasmic or membranous compartments of the same cells.

CONCLUSIONS

Our data identify a unique biological characterization of this rare pancreatic histotype. These findings provide a rationale for future studies evaluating the potential crosstalk between PD-L1/PD-1 axis and Notch pathways and prompting the development of novel therapeutics strategy.

Morphologic and Molecular Landscape of Pancreatic Cancer Variants as the Basis of New Therapeutic Strategies for Precision Oncology

To date, pancreatic cancer is still one of the most lethal cancers in the world, mainly due to the lack of early diagnosis and personalized treatment strategies. In this context, the possibility and the opportunity of identifying genetic and molecular biomarkers are crucial to improve the feasibility of precision medicine. In 2019, the World Health Organization classified pancreatic ductal adenocarcinoma cancer (the most common pancreatic tumor type) into eight variants, according to specific histomorphological features. They are: colloid carcinoma, medullary carcinoma, adenosquamous carcinoma, undifferentiated carcinoma, including also rhabdoid carcinoma, undifferentiated carcinoma with osteoclast-like giant cells, hepatoid carcinoma, and signet-ring/poorly cohesive cells carcinoma. Interestingly, despite the very low incidence of these variants, innovative high throughput genomic/transcriptomic techniques allowed the investigation of both somatic and germline mutations in each specific variant, paving the way for their possible classification according also to specific alterations, along with the canonical mutations of pancreatic cancer (KRAS, TP53, CDKN2A, SMAD4). In this review, we aim to report the current evidence about genetic/molecular profiles of pancreatic cancer variants, highlighting their role in therapeutic and clinical impact.

New therapeutic targets in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is associated with poor survival. Of all newly diagnosed patients, only about 20% can benefit from a potentially curative surgical resection, the remaining 80% presenting with unresectable locally advanced (LAPC) or metastatic (MPC) disease. Currently, there are limited therapeutic options for LAPC and MPC patients. Furthermore, despite intensive research efforts to better understand the molecular bases of PDAC and the biological relevance of its tumor microenvironment, treatments still largely consist of classical cytotoxic chemotherapy agents. Several studies of genetic and epigenetic sequencing have demonstrated the existence of 4 molecular PDAC subtypes, with heterogeneous genetic characteristics and different biological behaviour: squamous, pancreatic progenitor, immunogenic and aberrantly differentiated endocrine exocrine (ADEX). These distinct subtypes derive from alterations at multiple levels. Apart from the DNA repair pathway, however, none of these has so far been validated as a clinically relevant therapeutic target. Also, PDAC is unique from an immunological perspective and many studies have recently tried to elucidate the role of intratumoral effector T-cells, RAS oncogene, immunosuppressive leukocytes and desmoplastic reaction in maintaining the immunological homeostasis of this disease. However, there still remains much to be learned about the mechanisms whereby the pancreatic immune microenvironment promotes immune escape of cancer cells. Furthermore, while therapies targeting the stroma as well as immunotherapies hold promise for the future, these are not yet standard of care. This review aims to outline the state-of-the-art of LAPC and MPC treatment, highlighting data on the target therapies failure and current ongoing clinical trials on new promising therapeutic strategies.