Neoantigen-Targeted Vaccine Combined With Anti-PD-1 Antibody for Patients With Stage IV MMR-p Colon and Pancreatic Ductal Cancer

Inclusion Criteria:

* Age ≥18 years.
* Have histologically or cytologically - proven cancer of the pancreas or colon.
* Have tumor lesions amenable to repeated biopsy, and patient's acceptance to have a tumor biopsy of an accessible lesion at baseline and on treatment if the lesion can be biopsied with acceptable clinical risk (as judged by the investigator).
* Measurable disease as per RECIST 1.1.
* Have sufficient and accessible tissue for NGS and immune-phenotyping.
* Have not received any prior systemic therapy in the metastatic setting for PDA or CRC. Patients who have received adjuvant chemotherapy \>12 months prior to the diagnosis of metastatic disease may be eligible.
* ECOG performance status 0.
* Life expectancy of greater than 6 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:

* Is a candidate for definitive surgical resection.
* Is unwilling or unable to undergo standard of care therapy.
* Known history or evidence of brain metastases and/or leptomeningeal spread.
* Prior treatment with immunotherapy agents (including, anti-PD-1, anti-PD-L1, anti-PD-L2, anti-CTLA4, etc.).
* Receiving active immunosuppressive agents or chronic use of systemic corticosteroids within 14 days of vaccine treatment.
* Has active autoimmune disease that has required systemic treatment in the past 5 years, or a documented history of clinically severe autoimmune disease, or a syndrome that requires systemic steroids or immunosuppressive agents.
* Known history or concurrent interstitial lung disease.
* Has a pulse oximetry \< 95% on room air.
* Requires the use of home oxygen.
* Infection with HIV or hepatitis B or C.
* 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.
* Has been diagnosed with another cancer or myeloproliferative disorder within the past 5 year.
* Has had surgery within 28 days of dosing of investigational agent, excluding minor procedures (dental work, skin biopsy, etc.), celiac plexus block, and biliary stent placement.
* Has received any non-oncology live vaccine therapy used for prevention of infectious diseases within 28 days of study treatment.
* If at the time of signing informed consent, a regular user (including "recreational use") of any illicit drugs or other substance abuse (including alcohol) that could potentially interfere with adherence to study procedures or requirements.
* Any other sound medical, psychiatric, and/or social reason as determined by the Investigator.
* Unwilling or unable to follow the study schedule for any reason.
* Are pregnant or breastfeeding.
* Any radiological or clinical pleural effusions or ascites.
* Any peritoneal involvement by the tumor.
* History of malignant small bowel obstruction.
* On parenteral nutrition.
* Any liver metastasis greater than 3 cm or greater than 5 liver metastases.
* Known or suspected hypersensitivity to Hiltonol.