Irreversible Electroporation + Nivolumab for Patients With Metastatic Pancreatic Cancer

Inclusion Criteria: 1. Signed informed consent. 2. Histopathological confirmation of pancreatic adenocarcinoma. 3. At least one measurable primary in-situ (or locally-recurrent) or metastatic tumor must be present and, in the opinion of the investigators be amenable to IRE, and at least one additional metastatic tumor that will not undergo IRE. Both lesions must be accessible for image-guided percutaneous biopsy. 4. Age \> 18 years 5. Life expectancy greater than 3 months 6. ECOG (Eastern Cooperative Oncology Group) Performance Status (PS) 0-1 7. Patients must have normal organ and marrow function as defined below: * White blood cell count (WBC) ≥ 2 x 10⁹/L * Absolute neutrophil count (ANC) ≥ 1.5 x 10⁹/L * Hemoglobin ≥ 5,6 mmol/l * Platelet count ≥ 100 x 10⁹/L * Serum bilirubin ≤1.5 x upper limit of normal (ULN) (patients with Gilbert's Syndrome must have a total bilirubin ≤ 50 mmol/L ) * ASAT/ALAT ≤3 x ULN ( \< 5 x ULN if known liver metastasis) * PP ≥ 40 or INR ≤ 1.5 * Serum creatinine ≤ 1.5 x ULN or eGFR ≥ 40 mL/min 8. Women of childbearing potential (WOCBP) must use method(s) of contraception as indicated per protocol. 9. WOCBP must have a negative serum or urine pregnancy test (minimum sensitivity 25 IU/L or equivalent units of HCG) within 24 hours prior to the start of nivolumab. 10. Women must not be breastfeeding 11. Men who are sexually active with WOCBP must use any contraceptive method with a failure rate of less than 1% per year. 12. Men who are sexually active with WOCBP must continue contraception for 31 weeks (90 days plus the time required for nivolumab to undergo five half-lives) after the last dose of investigational drug. Exclusion Criteria: 1. Malignant ascites that is clinically detectable by physical examination or is symptomatic. 2. Prior treatment with an anti-PD-1, anti-PD-L1, anti-PD-L2, anti-CD137, or anti-CTLA-4 antibody, or any other antibody or drug specifically targeting T cell co-stimulation or checkpoint pathways 3. Radiotherapy, or major surgery within the last 2 weeks prior to entering the study 4. Any serious or uncontrolled medical disorder that, in the opinion of the investigator, may increase the risk associated with study participation or study drug administration, impair the ability of the subject to receive protocol therapy, or interfere with the interpretation of study results. 5. Patients should be excluded if they have an active, known or suspected autoimmune disease. 6. Patients should be excluded if they are positive test for hepatitis B virus surface anti-gen (HBV sAg) or hepatitis C virus ribonucleic acid (HCV antibody) indicating acute or chronic infection 7. Patients should be excluded if they have a condition requiring systemic treatment with either corticosteroids (\> 10 mg daily prednisone equivalents) or other immuno-suppressive medications within 14 days of study drug administration. Inhaled or topical steroids and adrenal replacement doses \> 10 mg daily prednisone equivalents are permitted in the absence of active autoimmune disease. 8. PD-1 inhibitors may cause hepatic toxicity which may lead to caution regarding other potentially hepatotoxic drugs. 9. Allergies and Adverse Drug Reaction * History of allergy to study drug components * History of severe hypersensitivity reaction to any monoclonal antibody 10. Patients are excluded if they have active brain metastases or leptomeningeal metastases. Subjects with brain metastases are eligible if metastases have been treated and there is no magnetic resonance imaging (MRI) evidence of progression for \[lowest minimum is 4 weeks or more\] after treatment is complete and within 28 days prior to the first dose of nivolumab administration. There must also be no requirement for immunosuppressive doses of systemic corticosteroids (\> 10 mg/day prednisone equivalents) for at least 2 weeks prior to study drug administration 11. Contraindications for IRE: * Implanted pacemaker or ICD (Implantable cardioverter defibrillator) unit. * History of epilepsy * History of cardiac arrhythmia * Recent myocardial infarction