Phase I/II Study of SBRT and GC4711 for Centrally Located or Large NSCLC

1. Male or female subjects at least 18 years of age. 2. Ability to understand and the willingness to sign a written informed consent. 3. Histological or biopsy proven NSCLC. 4. ECOG performance status of 0-3. 5. Node negative (T1 to T3N0M0), centrally located (within 2cm in all directions around the proximal bronchial tree, including ultra-central tumors, abutting the bronchial tree or trachea) or large (\>1-7cm) Non-Small Cell Lung Cancer (NSCLC), judged acceptable for SBRT by the treating Investigator 6. Adequate end-organ function, based on routine clinical and laboratory workup: 1. ANC \>1,000 cells/µl, Platelets ≥ 75,000 cells/µl, Hemoglobin ≥ 7.0 g/dl 2. Serum creatinine ≤ 2 x ULN or calculated creatinine clearance ≥ 30 ml/min 3. Total bilirubin ≤ 1.5 x ULN (or direct bilirubin below the ULN), AST and ALT ≤ 2.5 x ULN 7. Males and females of must agree to use effective contraception starting prior to the first day of treatment and continuing after the last dose of GC4711/Placebo for 30 days (females) and 90 days (males).

1. Subjects with confirmed nodal and/or distant disease(including brain), according standard workup by local investigator 2. Subjects with peripheral lesions 1cm or smaller 3. Prior treatment with immunotherapy within 3 months prior to Day 1 dosing. 4. Prior intra-thoracic radiotherapy or surgery with substantial overlap to planned radiation fields as determined by the treating radiation oncologist. 5. Subjects not recovered/controlled from prior treatment-related (chemotherapy or targeted therapy) toxicities judged by treating physician. 6. Uncontrolled malignancy other than lung cancer that requires active treatment or is deemed by the treating physicians to be likely to affect the subject's survival duration. 7. History of allergic reactions attributed to compounds of similar chemical or biologic composition to GC4711. 8. Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that, in the opinion of the investigator, would limit compliance with study requirements. 9. Participation in other clinical trials actively testing new anti-cancer treatments, unless previously written approval is provided by the Sponsor. 10. Requirement for concurrent treatment with nitrates or other drugs that may, in the judgment of the treating investigator, create a risk for a precipitous decrease in blood pressure. 11. Female subjects who are pregnant or breastfeeding. 12. Any other conditions that, in the Investigator's opinion, might indicate the subject to be unsuitable for the study.