A Study of Ad-RTS-hIL-12 With Veledimex in Subjects With Breast Cancer

Inclusion Criteria: 1. Female, age ≥ 18 years 2. Histologically-confirmed, locally advanced or metastatic adenocarcinoma of the breast 3. Achievement of SD or PR after a minimum of 12 weeks of pre-study first- or second-line standard chemotherapy 4. Presence of at least 2 measurable lesions 5. Standard treatment interrupted, except if anti-HER2 therapy 6. All treatment-related or radiation-related toxicities resolved to Grade 1 or lower 7. Submission of copies of tumor measurements and scans 8. Life expectancy \> 12 weeks 9. ECOG performance status of 0 to 1 10. Adequate bone marrow function 11. Adequate liver function 12. Adequate renal function 13. Female subjects and their male partners must agree must agree to use a highly reliable method of birth control 14. Able to swallow oral medication 15. Willing to comply with study procedures Exclusion Criteria: 1. Metastatic breast cancer patients currently on hormonal therapy as first- or second-line are not permitted 2. Prior radiation therapy encompassing \> 25% of bone marrow 3. Any congenital or acquired condition leading to compromised ability to generate an immune response 4. Immunosuppressive therapy 1. Use of systemic immunosuppressive drugs 2. Requirement for continual immune suppression 5. Major surgery within 4 weeks of study treatment 6. An active, second potentially life-threatening cancer 7. Presence of brain or subdural metastases 1. Any signs and/or symptoms of brain metastases must be stable for ≥ 4 weeks 2. Radiographic stability should be determined by comparing contrast-enhanced CT or MRI scans at screening to scans obtained by the same method at least 4 weeks earlier 8. Presence or documented history of any of the following autoimmune conditions: 1. Inflammatory bowel disease 2. Rheumatoid arthritis, systemic progressive sclerosis (scleroderma), systemic lupus erythematosus, autoimmune vasculitis 3. Motor neuropathy considered of autoimmune origin 9. Presence of meningeal carcinomatosis 10. Use of any medications that induce, inhibit, or are substrates of CYP450 3A4 11. History or evidence of cardiac disease as indicated by any of the following: 1. Congestive heart failure greater than NYHA Class II 2. Unstable angina or new-onset angina (begun within the last 3 months), or myocardial infarction within the 6 months prior to enrollment 3. Cardiac ventricular arrhythmias requiring anti-arrhythmic therapy 4. Congenital long QT syndrome or taking drugs known to prolong the QT interval 12. Current use of any drugs with a known risk of causing torsades de pointes 13. Evidence or history of thromboembolic, venous, or arterial events within the past 3 months 14. Evidence or history of bleeding diathesis or coagulopathy 15. International normalized ratio (INR) and activated partial thromboplastin time (aPTT) \> 1.5 x ULN, in subject who is not therapeutically anticoagulated. 16. History of malabsorption syndrome or other condition that would interfere with enteral absorption 17. Presence of active clinically serious infection 18. Diagnosis of infection with HIV or chronic infection with hepatitis B or C 19. Any other unstable or clinically significant concurrent medical condition 20. Pregnant or breast-feeding 21. Use of any investigational, non-United States Food and Drug Administration (US FDA) approved drug 22. Participation in any other clinical trial 23. Presence of any condition which makes the patient unsuitable