Study of Efficacy and Safety of NIS793 (With and Without Spartalizumab) in Combination With SOC Chemotherapy in First-line Metastatic Pancreatic Ductal Adenocarcinoma (mPDAC)

1. Previous radiotherapy, surgery (with exception of placement of biliary stent, which is allowed), chemotherapy or any other investigational therapy for the treatment of metastatic pancreatic cancer. Participants having received previous chemotherapy in the adjuvant setting. 2. Participants amenable to potentially curative resection. 3. Participants with a diagnosis of pancreatic neuroendocrine tumors (NETs), acinar, or islet cell tumors. 4. Having out of range laboratory values as pre-defined in the protocol. 5. Participants with MSI-H pancreatic adenocarcinoma. 6. Presence of symptomatic CNS metastases, or CNS metastases that require local CNS directed therapy (such as radiotherapy or surgery), or increasing doses of corticosteroids 2 weeks prior to study entry. 7. History of severe hypersensitivity reactions to any ingredient of study drug(s) and other mAbs and/or their excipients. 8. The participant exhibits any of the events outlined in the contra-indications or special warnings and precautions sections of gemcitabine and nab-paclitaxel as per locally approved labels. 9. Impaired cardiac function or clinically significant cardiac disease. 10. Known history of testing positive HIV infection. 11. Active HBV or HCV infection. Participants whose disease is controlled under antiviral therapy should not be excluded. 12. History of or current interstitial lung disease or pneumonitis grade ≥ 2