Inclusion Criteria:
* Histologically or cytologically confirmed locally advanced pancreas adenocarcinoma that is considered borderline resectable or unresectable per institutional standardized criteria of unresectability or medical inoperability (NCCN guidelines 2.2021 PANC-C 1 of 2).
* Patients with locoregional adenopathy are eligible as long as all suspicious lymph nodes are deemed to be adjacent to the primary tumor as per radiation oncologist assessment.
* At least 3 months of systemic chemotherapy for this disease without progression of local or systemic disease. Newly diagnosed patients may be screened for enrollment in this study and can be enrolled once they have completed 3 months of systemic chemotherapy (and still meet all eligibility criteria) prior to the start of study treatment.
* At least 18 years of age.
* ECOG performance status ≤ 1
* Life expectancy \> 3 months
* Normal bone marrow and organ function within 21 days of randomization as defined below:
* Absolute neutrophil count ≥ 1,500/mcL
* Platelets ≥ 100,000/mcL
* Hemoglobin ≥ 9.0 g/dL
* Total bilirubin ≤ 1.5 x IULN; no prior history of Gilbert's syndrome
* AST(SGOT)/ALT(SGPT) ≤ 2.5 x IULN or ≤ 5.0 x IULN if due to liver involvement by tumor
* Creatinine clearance ≤ 1.5 x IULN or glomerular filtration rate of ≥ 60 mL/min
* INR ≤ 1.5 x IULN unless patient is receiving anticoagulant therapy as long as INR or PTT is within therapeutic range of intended use of anticoagulants
* aPTT ≤ 1.5 x IULN unless patient is receiving anticoagulant therapy as long as INR or PTT is within therapeutic range of intended use of anticoagulants
* Albumin ≥ 2.5 mg/dL
* Corrected QT interval (QTc) \< 480 ms (as calculated by the Fridericia correction formula).
* The effects of defactinib on the developing human fetus are unknown. For this reason and because radiation therapy is known to be teratogenic, women of childbearing potential and men must agree to use highly effective contraception (hormonal or barrier method of birth control, abstinence) prior to study entry and for the duration of study participation. Should a woman become pregnant or suspect she is pregnant while participating in this study, she must inform her treating physician immediately. Men treated or enrolled on this protocol must also agree to use adequate contraception prior to the study, for the duration of the study, and 120 days after completion of the study
* Ability to understand and willingness to sign an IRB approved written informed consent document
Exclusion Criteria:
* A history of other malignancy with the exception of malignancies for which all treatment was completed at least 2 years before registration and the patient has no evidence of disease.
* Clinical evident ascites or pleural effusion that requires therapeutic paracentesis or thoracentesis.
* Prior treatment with a drug of the FAK inhibitor class or with an anti-PD-1, anti-PD-L1, anti-PD-L2, anti-CD137, or anti-cytotoxic T-lymphocyte associated antigen 4 (CTLA-4) antibody (including ipilimumab or any other antibody or drug specifically targeting T-cell co-stimulation or checkpoint pathways.
* Prior anti-human antibody response (AHA or ADA).
* Currently receiving any other investigational agents or has receive any other investigational agents within 4 weeks or 5 half-lives or planned first dose of study agents.
* A history of allergic reactions attributed to compounds of similar chemical or biologic composition to defactinib or other agents used in the study.
* Has a diagnosis of immunodeficiency or is receiving chronic systemic steroid therapy or any other form of immunosuppressive therapy not routinely associated with chemotherapeutic regimen.
* Requires continued use of warfarin for anticoagulation and cannot stop warfarin or be safely switched to another anticoagulant or direct oral anticoagulant
* Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, hypertension, immunosuppression, autoimmune conditions, or underlying pulmonary disease.
* Has an active autoimmune disease requiring systemic treatment within the past 2 years (i.e. with use of disease modifying agents, corticosteroids, or immunosuppressive drugs). Replacement therapy (e.g., thyroxine, insulin, or physiologic corticosteroid replacement therapy for adrenal or pituitary insufficiency, etc.) is not considered a form of systemic treatment.
* Received a live vaccine within 30 days prior to the first study treatment. Examples of live vaccines include, but are not limited to, the following: measles, mumps, rubella, varicella/zoster (chicken pox), yellow fever, rabies, Bacillus Calmette-Guérin (BCG), and typhoid vaccine. Seasonal influenza vaccines for injection are generally killed virus vaccines and are allowed; however, intranasal influenza vaccines (e.g. FluMist) are live attenuated vaccines and are not allowed.
* Known history of hepatitis B (defined as hepatitis B surface antigen \[HBsAg\] reactive) or known active hepatitis C virus (defined as HCV RNA \[qualitative\] is detected).
* Has a history of (non-infectious) pneumonitis that required steroids or current pneumonitis.
* Has a known history of active TB (bacillus tuberculosis).
* Major surgery within 28 days prior to the first study treatment.
* Pregnant and/or breastfeeding. Women of childbearing potential must have a negative pregnancy test within 14 days of study entry.
* Patients with HIV are eligible unless their CD4+ T-cell counts are \< 350 cells/mcL or they have a history of AIDS-defining opportunistic infection within the 12 months prior to registration. Concurrent treatment with effective ART according to DHHS treatment guidelines is recommended.
* Known SARS-Cov2 infection ≤28 days prior to first dose of study therapy.
* Exposure to P-glycoprotein (P-gp) inhibitors or inducers within 14 days prior to the first dose and during the course of therapy.
* Subjects with the inability to swallow oral medications or impaired gastrointestinal absorption due to gastrectomy or active inflammatory bowel disease.
* Subjects with a history of hypersensitivity to any of the inactive ingredients (hydroxypropylmethylcellulose, mannitol, magnesium stearate) of the investigational product.
