A Study to Evaluate the Safety and Tolerability of SX-682 in Combination with Nivolumab As a Maintenance Therapy in Patients with Metastatic Pancreatic Ductal Adenocarcinoma

Inclusion Criteria:

Written Informed Consent and HIPAA Authorization

1. Subjects must have the nature of the study explained to them

2. Subjects must be willing and able to comply with scheduled visits, treatmentschedule, laboratory tests, pharmacokinetic collections, study biopsies and otherrequirements of the study.

3. Subjects (or an acceptable proxy) must provide a signed and dated IRB/IEC approvedwritten informed consent form (ICF) in accordance with regulatory and institutionalguidelines for both the study and exploratory biomarker analysis obtained via pairedbiopsies.

4. Subjects (or an acceptable proxy) must provide a signed and dated Health InsurancePortability and Accountability Act (HIPAA) authorization.

5. The ICF and HIPAA authorization must be obtained before conduction and proceduresthat do not form a part of the subject's normal care.

6. After signing the ICF and HIPAA Authorization, subjects will be evaluated for studyeligibility during the Screening Period (no more than 28 days before study drug

administration) according to the following further inclusion/exclusion criteria:

Study Population/Inclusion Criteria

1. Male or female subjects, aged at least 18 years

2. Have histologically or cytologically confirmed metastatic pancreatic ductaladenocarcinoma

3. Completion of at least 16 weeks of first line chemotherapy without evidence ofdisease progression

4. Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1.

5. Must have measurable disease with at least 1 unidimensional measurable lesion periRECIST

6. Screening laboratory values within 14 days prior to first dose of study drug: WBC ≥ 3000/µL Neutrophils ≥ 1500/µL Platelets ≥ 100,000>µL Hemoglobin ≥ 9.0 g/dL inthe absence of blood transfusion Creatinine ≤ 1.5 mg/dL AST/ALT ≤ 2.5 x ULN forsubjects with no liver metastases

• 5 x ULN for subjects with liver metastases Bilirubin ≤ 1.5 mg/dL sa≤ 3.0 mg/dLfor subjects with Gilbert's disease INR or PT ≤ 1.5 x ULN unless receivinganticoagulation therapy aPTT or PTT ≤ 1.5 x ULN unless receivinganticoagulation therapy

7. Life expectancy of ≥ 12 weeks as judged by the treating physician.

8. Patient must consent for baseline and on treatment biopsies

9. Patients must have baseline pulse oximetry ≥ 90% on room air

Exclusion Criteria:

Target Disease Exceptions:

Active brain metastases or leptomeningeal metastases. Subjects with brain metastases are eligible if these have been treated and there is no magnetic resonance imaging (MRI- except where contraindicated, in which case a CT scan is acceptable) evidence of progression for at least 8 weeks after treatment is complete and within 28 days prior to first dose of study drug administration. An MRI is not required to rule out brain metastases or leptomeningeal metastases. There must also be no requirement for high doses of systemic corticosteroids that could result in immunosuppression (>10 mg/day prednisone equivalents) for at least 2 weeks prior to study dry administration.

Medical History and Concurrent Disease

Any serious or uncontrolled medical disorder that, in the opinion of the investigator, may increase the risk associated with study participation or study drug administration, impair the ability of the subject to receive protocol therapy, or interfere with the interpretation of study results. Specifically:

1. Subjects with active, non-infectious pneumonitis.

2. Subjects with interstitial lung disease or a history of pneumonitis that requiredoral or intravenous glucocorticoids to assist with management.

3. Subjects with clinically significant heart disease that affects normal activities.

4. Clinically significant cardiovascular/ cerebrovascular disease defined as cerebralvascular accident, stroke, carotid artery disease transient ischemic attach (< 6months prior to enrollment), myocardial infarction (<6 months prior to enrollment),unstable angina, congestive heart failure (New York Heart Association ClassificationClass >II) or serious cardiac arrhythmia.

5. Prior malignancy active within the previous 3 years except for locally curablecancers that have been apparently cured, such as basal or squamous cell skin cancer,superficial bladder cancer, or carcinoma in situ of the prostate, cervix or breast.

6. Subjects with active, known or suspected autoimmune disease. Subjects with vitiligo,type I diabetes mellitus, residual hypothyroidism due to autoimmune condition onlyrequiring hormone replacement, psoriasis not requiring systemic treatment, orconditions not expected to recur in the absence of an external trigger are permittedto enroll.

7. Subjects with a condition (including organ or bone marrow transplant) requiringsystemic treatment with either corticosteroids (> 10 mg daily prednisoneequivalents) or other immunosuppressive medications. Inhaled or topical steroids,and adrenal replacement doses > 10 mg daily prednisone equivalents are permitted inthe absence of active autoimmune disease.

8. Use of other investigational drugs (drugs not marketed for any indication) ormedications at immunosuppressive doses within 28 days before study drugadministration.

9. Patients who received immunotherapy or investigational drug within 4 weeks prior toenrollment.

10. Patients who underwent major surgery within 4 weeks of enrollment (not includingdiagnostic laparoscopy)

11. History of myelodysplastic syndromes or myeloproliferative neoplasms.

12. History of or medication induced prolonged QT interval.

13. Any botanical preparation (e.g., herbal supplements or traditional Chinesemedicines) intended to treat the disease under study or provide supportive care. Useof marijuana and its derivatives for treatment of symptoms related to cancertreatment, even if obtained by medical prescription or if its use (even without amedical prescription) has been legalized locally.

Physical and Laboratory Test Findings

1. A history of Hepatitis B or C, either acute or chronic, as indicated by HBV surfaceantigen positivity, HBV core antibody positivity, or positive HCV antibody withreflex to positive HCV RNA.

2. Known history of testing positive for human immunodeficiency virus (HIV) or knownacquired immunodeficiency syndrome (AIDS).

3. Active tuberculosis (history of exposure or history of positive tuberculosis testplus presence of clinical symptoms, physical or radiographic findings).

4. EKG demonstrating a QTc interval >470 msec or patients with congenital long QTsyndrome.

Allergies and Adverse Drug Reaction

1. History of allergy to study drug components (examples: hydroxpropylmethylcellulosephthalate (hypromellose phthalate or HPMCP), microcrystalline cellulose, sodiumcroscarmellose, sodium lauryl sulfate, and silicon dioxide).

2. History of severe hypersensitivity reaction to any monoclonal antibody (Grade ≥ 3NCI-CTCAE v5).

3. History of anaphylaxis, or recent (within 5 months) history of uncontrolled asthma.

Sex and Reproductive Status/Special Populations

1. Women of childbearing potential (WOCBP) must use method(s) of contraception with afailure rate of less than 1% while on study and for 5 months after the last dose ofSX-682 or nivolumab. A WOCBP is defined as any female who has experienced menarcheand who has not undergone surgical sterilization (hysterectomy or bilateraloophorectomy) or is not postmenopausal. Menopause is defined clinically as 12 monthsof amenorrhea in a woman over age 45 in the absence of other biological orphysiological causes.

2. Women under the age of 62 with a history of being postmenopausal must have adocumented serum follicle stimulating hormone, (FSH) level > 40 mIU/mL.

3. Women must have a negative serum or urine pregnancy test (minimum sensitivity 25IU/L or equivalent units of HCG) within 24 hours prior to the start of study drug.

4. Women must not be breastfeeding.

5. Men who are sexually active with WOCBP must use any contraceptive method with afailure rate of less than 1% per year while on study and for a period at least 7months after the last dose of study drug.

6. Women who are not of childbearing potential and azoospermic men do not requirecontraception.

7. Individuals who are incarcerated, compulsory detained or otherwise considered avulnerable population