AB801 in Combination With Chemotherapy and Immunotherapy for the Treatment of Patients With Borderline Resectable, Locally Advanced or Metastatic Cholangiocarcinoma or Pancreatic Cancer

Inclusion Criteria: * Male or female ≥ 18 years of age and willing and able to provide informed consent * Previously untreated cytologically or histologically confirmed, at least one measurable lesion via Response Evaluation Criteria in Solid Tumors (RECIST 1.1) of cholangiocarcinoma or pancreatic adenocarcinoma meeting following criteria: * Cholangiocarcinoma * Borderline resectable/locally advanced cholangiocarcinoma: to be defined as unresectable disease on evaluation by a hepatobiliary multi-disciplinary tumor board/surgeon based on tumor size/location, vascular involvement, and absence of extrahepatic metastasis. * Metastatic cholangiocarcinoma: Patients with metastatic cholangiocarcinoma patient who have not received prior systemic therapy * Pancreatic adenocarcinoma * Borderline resectable pancreatic adenocarcinoma: There are multiple definitions of borderline resectable pancreatic ductal adenocarcinoma (PDAC). For the purposes of this study, borderline resectable disease will be identified per the National Comprehensive Cancer Network (NCCN) criteria. Per this definition, borderline resectable PDAC is defined as the presence of any one or more of the following on CT: * An interface between the tumor and superior mesenteric artery (SMA) or celiac axis (CA) measuring \< 180º of the circumference of the vessel wall. * An interface between the tumor with the common hepatic artery without extension into the celiac axis or hepatic artery bifurcation allowing for safe and complete resection and reconstruction. * An interface between the primary tumor and the superior mesenteric vein or portal vein (SMV-PV) measuring ≥ 180° of the circumference of the vessel wall * Short-segment occlusion of the SMV-PV with normal vein above and below the level of obstruction that is amenable to resection and venous reconstruction * An interface between the primary tumor and the inferior vena cava (IVC) * Locally advanced pancreatic adenocarcinoma: Multiple guidelines defining locally advanced PDAC have been developed. For the purposes of this study, locally advanced PDAC cases will be identified per the definition developed by the NCCN. Per this definition, locally advanced PDAC is defined as presence of any one or more of the following on CT: * Interface between the tumor and SMA or CV measuring \> 180º of the circumference of the vessel wall or solid tumor contact with the CA and aortic involvement. * Occlusion of the SMV-PV that is not amenable to resection and venous reconstruction * Metastatic pancreatic adenocarcinoma: Patients with metastatic pancreatic adenocarcinoma who have not received prior systemic therapy * Eastern Cooperative Oncology Group (ECOG) performance status of 0-1 * Absolute neutrophil count (ANC) ≥ 1.5x10\^9/L * Platelets ≥ 100x10\^9/L * Hemoglobin ≥ 9 g/dL * Creatinine clearance (Ccr) ≥ 50 mL/min (as calculated by Modified Cockcroft-Gault formula) * Serum total bilirubin ≤ 2x upper limit of normal (ULN) or \< 3x ULN if Gilbert's syndrome * Aspartate aminotransferase (AST) (serum glutamic-oxaloacetic transaminase \[SGOT\]) and alanine aminotransferase (ALT) (serum glutamic-pyruvic transaminase \[SGPT\]) ≤ 2.5 X ULN; \< 5x ULN in patients with liver metastases * Women with no childbearing potential because of surgery or who are at least 1 year postmenopausal (ie, 12 months post last menstrual period) or with menopause confirmed by follicle-stimulating hormone testing, OR * Women of childbearing potential (defined as any female who has experienced menarche and is not permanently sterile or post-menopausal) must use an effective nonhormonal method of contraception (intrauterine device or intrauterine system; condom or occlusive cap \[diaphragm or cervical or vault caps\] with spermicidal foam or gel or film or cream or suppository; or vasectomized male partner if he is the sole partner of that participant) or practice true abstinence for the duration of the study and for up to 14 months after the last systemic treatment * Male participants must use an effective method of contraception (condom or occlusive cap \[diaphragm or cervical or vault caps\] with spermicidal foam or gel or film or cream or suppository; or vasectomy) or practice true abstinence as defined throughout the study and for up to 11 months after the systemic treatment * Immunosuppressive doses of systemic medications, such as corticosteroids or absorbed topical corticosteroids (doses \> 10 mg/day prednisone or equivalent) must be discontinued at least 2 weeks (14 days) before study treatment administration. Physiologic doses of corticosteroids (≤ 10 mg/day of prednisone or its equivalent) or short pulses of corticosteroids (≤ 3 days) may be permitted * Products with known potential to prolong the corrected QT (QTc) interval should be avoided when possible. When able will replace non-prolonging QTc acting drug when available and if medically necessary * Major surgery as defined by the Investigator must be completed at least 4 weeks before study treatment administration. Participants should have recovered from the surgical procedure prior to the first dose being administered * Adequate baseline tumor tissue sample for correlative studies Exclusion Criteria: * Previous treatment with any of planned study drugs in cholangiocarcinoma, though patients with one cycle of gemcitabine/cisplatin/durvalumab will be considered eligible * Previous treatment with any of planned study drugs in pancreatic adenocarcinoma, though patients with one cycle of FOLFIRINOX will be considered eligible * Peripheral neuropathy \> grade 2 * Known status of HIV which is not well-controlled (CD4 \< 300) at the time of study eligibility. Patients with controlled and treated HIV/hepatitis C virus (HCV) and an undetectable viral load are allowed * Untreated hepatitis B infection; Patient has known active hepatitis B virus (HBV) or hepatitis C virus (HCV), or human immunodeficien