INCMGA00012 in Patients With Previously Treated Unresectable or Metastatic Adenosquamous Pancreatic or Ampullary Cancer

Inclusion Criteria:

* Age ≥18 years.
* Have histologically or cytologically - proven adenosquamous carcinoma of the pancreas or ampulla.
* Has unresectable or metastatic measurable disease.
* Has received (or been intolerant to or ineligible for) at least 1 prior line of cytotoxic chemotherapy and received no more than 2 prior systemic treatments.
* Presence of at least one lesion with measurable disease.
* Accept to have a tumor biopsy of an accessible lesion at baseline and on treatment.
* Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1.
* If HIV-positive, then all of the following criteria must also be met: cluster of differentiation (CD) 4+ count ≥ 350/μL, undetectable viral load, and receiving highly active antiretroviral therapy.
* Life expectancy of greater than 3 months.
* Patients must have adequate organ and marrow function defined by study-specified laboratory tests prior to initial study drug.
* Woman of childbearing potential must have a negative pregnancy test and follow contraceptive guidelines as defined per protocol.
* Men must use acceptable form of birth control while on study.
* Ability to understand and willingness to sign a written informed consent document.

Exclusion Criteria

* Known history or evidence of brain metastases.
* Has had chemotherapy, radiation, or biological cancer therapy within 14 days prior to the first dose of study drug.
* Has received an investigational agent or used an investigational device within 28 days of the first dose of study drug.
* Expected to require any other form of systemic or localized antineoplastic therapy while on study.
* Has had major surgery within 28 days of dosing of investigational agent, excluding minor procedures.
* Has received a live vaccine within 28 days prior to the first dose of study drug.
* Prior treatment with immunotherapy agents (including, anti-PD-1, anti-PD-L1, anti-PD-L2, anti-CTLA4, anti-OX40 and LAG-3 antibodies)
* Have used any systemic steroids within 14 days of study treatment.
* Hypersensitivity reaction to any monoclonal antibody.
* Evidence of clinical or radiographic ascites.
* Have clinically significant and/or malignant pleural effusion.
* Uncontrolled intercurrent illness including, but not limited to, uncontrolled infection, symptomatic congestive heart failure, unstable angina, cardiac arrhythmia, metastatic cancer, or psychiatric illness/social situations that would limit compliance with study requirements.
* History of autoimmune disease requiring systemic immunosuppression within the last 2 years.
* Presence of any tissue or organ allograft, regardless of need for immunosuppression, including corneal allograft. Patients with a history of allogeneic hematopoeitic stem cell transplant will be excluded.
* All toxicities attributed to prior anti-cancer therapy other than alopecia and fatigue must have resolved to a grade 1 or baseline before administration of study drug.
* Infection with Hepatitis A, B or C.
* Patient has a pulse oximetry of \<92% on room air.
* Patient is on supplemental home oxygen.
* Has an unhealed surgical wound or ulcer, or a bone fracture considered non-healing.
* Patient has clinically significant heart disease.
* Patient is, at the time of signing informed consent, a regular user (including "recreational use") of any illicit drugs or other substance abuse.
* Unwilling or unable to follow the study schedule for any reason.
* Patient has history of non-infectious pneumonitis.
* Serum albumin level less than 2.8 g/dL.