Pancreatic ductal adenocarcinoma (PDAC) complexity, where genetic, stromal, and immunological factors all interact with each other, is responsible for the overall poor response of PDAC to chemotherapeutic agents, making this a lethal disease. The investigators hypothesize that: (i) dissection of genetic, stromal, and immunological factors on endoscopic ultrasound fine needle biopsy (EUS-FNB) tissue samples from unresectable PDAC patients' will allow to determine prognostic factors in this patient population; (ii) treatment response and acquisition of tumor chemotherapy resistance could be related to genetic heterogeneity between the primary and metastatic sites and alteration of the molecular profile under drug' selection pressure.

Inclusion Criteria:

• Patients referred to EUS with FNB for suspected pancreatic cancer unresectable or metastatic based on imaging findings
• Availability of biopsies obtained during EUS-FNB
• Histological diagnosis of pancreatic ductal adenocarcinoma of any stage
• Patients must be fit for chemotherapy administration
• They have to express their willingness to be followed up at our pancreatic high volume centers
• Age >18 and <80 years
• Able to sign informed consent

Exclusion Criteria:

• Histological diagnoses other than pancreatic ductal adenocarcinoma
• Pregnancy or lactation

This study concerns consecutive individuals with a solid pancreatic lesion who will undergo diagnostic EUS-FNB over a 3 year period. Those with a histological diagnosis of PDAC will be enrolled in the study. Enrollment will include patients with unresectable disease, which can be divided in different stages, i.e. borderline resectable, locally advanced, and metastatic.