Subjects with MSI-H pancreatic cancer who have not previously received pembrolizumab. advanced pancreatic cancer PHASE IB: No prior treatment with erlotinib is allowed for pancreatic cancer patients Patients may have had prior adjuvant treatment for pancreatic cancer; the last dose of chemotherapy must have been > 4 months prior to study entry; patients with prior radiotherapy are acceptable; it must be at least 4 months since administration of radiation therapy and all signs of toxicity must have abated For patients with pancreatic cancer:\r\n* Stage I-III cytologically or histologically-proven pancreatic adenocarcinoma\r\n* Cancer confirmed to be surgically resectable, with surgery evaluation with planned resection\r\n* Patients may have prior neoadjuvant chemotherapy, but no neoadjuvant chemoradiation\r\n* No cancer chemotherapy treatment 2 weeks prior to day 2 of treatment Prior use of chemotherapy, radiotherapy, and / or investigational agents for pancreatic cancer Histological or cytological proof of pancreatic adenocarcinoma; must have locally advanced or metastatic pancreatic cancer and received at least one dose of chemotherapy (any treatment line) and may have responding, stable or progressive disease Any prior treatment for pancreatic cancer Cystic pancreatic cancer; microcystic disease may be eligible First line treatment for metastatic pancreatic cancer. Have endocrine pancreatic tumors or ampullary cancer. Any prior radiotherapy or chemotherapy for pancreatic cancer Patients who received recent chemotherapy for pancreatic cancer are eligible; patients who received chemotherapy > 5 years ago for malignancies other than pancreatic cancer are also eligible, provided that chemotherapy was completed > 5 years ago and that there is no evidence of the second malignancy at the time of study entry PRE-SCREENING: Patients with advanced metastatic pancreatic cancer who have measurable disease Had prior systemic therapy for pancreatic cancer Any known active cancer other than pancreatic primary For LY3300054 + merestinib in pancreatic cancer: Have received any type of cancer immunotherapy including the same pancreatic cancer vaccine Have received any anti-pancreatic cancer therapy (symptomatic therapies are allowed) Prior radiotherapy for pancreatic cancer Prior surgical resection of pancreatic cancer Patients with pathologically confirmed pancreatic cancer referred for image-guided radiation therapy (IGRT) Locally advanced or metastatic pancreatic cancer for the pancreatic cancer cohort Prior systemic therapy for pancreatic cancer No prior treatment (chemotherapy, biological therapy, or radiotherapy) for resectable pancreatic cancer Patients who received chemotherapy > 5 years ago for malignancies other than pancreatic cancer are eligible Prior use of radiotherapy or investigational agents for pancreatic cancer Metastatic pancreatic cancer Histologically or cytologically confirmed carcinoma of exocrine pancreatic head amenable to oncological surgical resection per findings on a pancreatic-specific computed tomography (CT) scan/MRI scan; tumors of the body that allow a surgical approach similar to pancreatic head tumors are acceptable Prior radiation therapy for pancreatic cancer Radiographic evidence of pancreatic cancer recurrence Prior abdominal radiation therapy or prior chemotherapy for pancreatic cancer Endocrine or acinar pancreatic carcinoma Resectable pancreatic cancer Metastatic pancreatic cancer based on imaging Prior surgical or medical treatment for pancreatic cancer Pancreatic cancer cohort specific criteria:\r\n* Patients must have unresectable or metastatic pancreatic cancer\r\n* Patients must have failed at least one prior line of therapy for metastatic or unresectable disease or have recurred within 6 months of completing adjuvant chemotherapy\r\n* Patients with liver metastases must have < 50% involvement of the liver Received any systemic treatment for pancreatic cancer =< 14 days prior to first dose of rucaparib No prior chemotherapy or radiation for pancreatic cancer No definitive resection of pancreatic cancer Histological or cytological proof of pancreatic adenocarcinoma; must have locally advanced or metastatic pancreatic cancer who have received at least first line chemotherapy and may have responding, stable or progressive disease Have stable metastatic pancreatic cancer after receiving 8-12 doses of FOLFIRINOX (measurable disease is not required) Patients who have had any prior therapy for pancreatic cancer Pancreatic Cancer Pancreatic Cancer Subjects with one or more prior treatments for their pancreatic cancer. Prior chemotherapy or radiation for pancreatic cancer Diarrhea, grade 1 or greater by the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI-CTCAE, version [v.] 4.0); pancreatic cancer patients with clinical evidence of pancreatic insufficiency must be taking pancreatic enzyme replacement Subjects who have had radiotherapy for pancreatic cancer Patients must have had no prior chemotherapy or radiation therapy for pancreatic cancer Resectable pancreatic cancer Prior chemotherapy, targeted therapy, immunotherapy, or any clinical trials or radiotherapy for pancreatic cancer Willing and able to provide written informed consent: voluntary agreement to participate in the study following disclosure of risks and procedures required, including possibility of onset of exocrine pancreatic insufficiency with subsequent requirement for life-long pancreatic enzyme replacement Maldigestion/malabsorption syndrome pre-dating the diagnosis of pancreatic cancer. No prior treatment for pancreatic cancer Adequate pancreatic function Prior treatment with chemotherapy or radiation for pancreatic cancer or prior treatment with radiation for other diagnoses to expected pancreatic cancer treatment fields. Endocrine or acinar pancreatic carcinoma Prior treatment with any chemotherapy for metastatic disease from pancreatic cancer Diarrhea, grade 1 or greater by the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI-CTCAE, version [v.] 4.0); pancreatic cancer patients with clinical evidence of pancreatic insufficiency must be taking pancreatic enzyme replacement Metastatic Pancreatic Cancer Any prior chemotherapy or radiation for treatment of the patient’s pancreatic tumor Normal pancreatic function Part B only: Prior therapy (including investigational agents) for pancreatic cancer Prior treatment with chemotherapy or radiation for pancreatic cancer or prior treatment with radiation for other diagnoses to expected pancreatic cancer treatment fields. Any prior treatment (chemotherapy, radiation) for pancreatic cancer Prior pancreatic surgery Patient must not have received prior chemotherapy or radiation for pancreatic cancer Prior chemotherapy, immunotherapy or radiation for pancreatic cancer Any prior radiotherapy, chemotherapy, surgery, or investigational therapy for adjuvant or metastatic pancreatic cancer Any prior chemotherapy or radiation for treatment of the patient’s pancreatic tumor Prior therapy before Day 1 of Cycle 1 for the treatment of Stage IV pancreatic cancer Prior therapy before Day 1 of Cycle 1 for the treatment of Stage IV pancreatic cancer A diagnosis of pancreatic or other periampullary cancer is suspected preoperatively Known benign or indolent disease, including benign pancreatic cystic tumors or pancreatic endocrine tumors Are undergoing treatment for pancreatic cancer at Fox Chase Cancer Center (FCCC) mesothelioma, pancreatic cancer: 1-3 prior treatments Prior treatment of pancreatic cancer with chemotherapy in adjuvant setting, except those where at least 12 months have elapsed since completion of the last dose and no persistent treatment-related toxicities present Observational Arm only: patients with a pathological or clinical diagnosis of pancreatic cancer and beginning or continuing FOLFIRINOX chemotherapy Minocycline trial only: patients who have had prior treatment for pancreatic cancer within the past six months may be excluded at the discretion of the investigator Patients with prior pancreatic surgery or cancers One of the following high-risk groups\r\n* Patients will be eligible if they have 2 or more relatives with pancreatic cancer and have a first degree relationship with at least one of the relatives with pancreatic cancer\r\n** If only 2 family members are affected then both must have had pancreatic cancer and a first-degree relationship with individual screened\r\n** If there are more than 2 affected individuals on the same side of the family at least one of the individuals must have a first-degree relationship with the member being screened\r\n** Patients at least 40 years (yrs) old or 10 yrs younger than the youngest affected individual\r\n* Peutz-Jeghers syndrome (PJS) patients age > 30\r\n* Hereditary pancreatitis patients\r\n* Patients with familial atypical multiple mole melanoma syndrome (FAMMM)\r\n* Patients with BRCA2 mutation and at least one first or second degree relative with documented pancreatic cancer Pancreatic insufficiency or disease Pancreatic carcinoma: Determined unresectable by a pancreatic cancer surgeon or a multi-disciplinary or gastrointestinal oncology Tumor Board Patients who have received chemotherapy for pancreatic cancer, other than up to 4 cycles of mFOLFIRINOX as noted above GROUPS 1, 2, AND 3: Group 1: participants identified as being high-risk for familial or hereditary pancreatic cancer, and must conform to one or more of the following requirements:\r\n* Have a strong family history of pancreatic cancer; this is defined as pancreatic cancer occurring in one first- degree relative and two other relatives, or two first- degree relatives; or, \r\n* Have a known high-risk genetic syndrome (e.g., BRCA 1&2, STK11, CDNK2A, PRSS1, and MSH 2&6) HEALTHY VOLUNTEERS (Group 4): Group 4 participants must have no history of cancer, pancreatic disease, or family history of pancreatic cancer\r\n* Family history will be defined as pancreatic cancer occurring in one first-degree relative and two other relatives, or two first-degree relatives Patients with histologic or cytologic proof of pancreatic cancer, for whom the treatment plan, at the time of enrollment, is chemoradiation Any prior systemic or investigational therapy for pancreatic cancer Histological diagnosis of prostate, pancreatic or bladder cancer Undergoing pancreatic cancer resection PANCREATIC CANCER PATIENT INCLUSION CRITERIA: PANCREATIC CANCER PATIENT EXCLUSION CRITERIA: Patients who will undergo curative pancreatectomy for pancreatic adenocarcinoma, pancreatic neuroendocrine tumors, or pancreatic cysts (malignant or benign) (PCS study)