Niraparib and Dostarlimab for the Treatment of Germline or Somatic BRCA1/2 and PALB2 Mutated Metastatic Pancreatic Cancer

Inclusion Criteria: * Presence of either a germline deleterious mutation or somatic deleterious mutation in any one of the genes in our proposed gene-panel as determined by any of the commercially available or institutional testing platforms. Note: The somatic mutation could be either on a tissue-based test or the circulating tumor DNA (ctDNA)-based assay. The 6 genes that would determine eligibility would be: BRCA1/2, PALB2, BARD1, RAD51c, RAD51d * Provide written informed consent * Histological/cytological confirmation of diagnosis of metastatic pancreatic ductal adenocarcinoma * At least one but no more than two prior lines of systemic therapy for metastatic disease (maintenance therapy is not considered a line of treatment) * Note: Patients who have not had any prior chemotherapy can refuse chemotherapy and be considered eligible. This refusal and their reason for refusal would have to be documented * Received a platinum agent as part of first or second line treatment (unless contraindicated) * Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 * Serum creatinine =\< 1.5 x upper limit of normal (ULN) or estimated glomerular filtration rate (eGFR) \>= 60 mL/min using the Cockcroft-Gault Equation (=\< 14 days prior to registration) * Hemoglobin \>= 9.0 g/dL (=\< 14 days prior to registration) * Absolute neutrophil count \>= 1500/uL (=\< 14 days prior to registration:) * Platelets \>= 100 x 10\^9/L (=\< 14 days prior to registration) * Total bilirubin…