<qa>  What is the primary endpoint of SBRT?Based on promising data from our laboratory demonstrating synergy between ablative local radiotherapy and FLT3 ligand immunotherapy in murine NSCLC models, investigators are performing a phase II study combining FLT3L immunotherapy and SBRT for patients with advanced NSCLC that has progressed following standard systemic therapy. All patients will receive daily subcutaneous injections of CDX-301 75 μgkg for 5 days, beginning on the first day of SBRT. SBRT will be delivered to a single pulmonary lesion. Depending on the size and location of the target lesion, the SBRT regimen will be 34 Gy x 1 peripheral tumors smaller than 2 cm and not adjacent to the chest wall, 18 Gy x 3 peripheral tumors not eligible for 34 Gy x 1, or 10 Gy x 5 central tumors. The primary endpoint will be progression-free survival at 4 months, defined using immune-related response criteria irRC. A total of 29 patients will be enrolled. 