AN OPEN-LABEL, MULTICENTER CLINICAL TRIAL WITH NIVOLUMAB (BMS-936558) MONOTHERAPY IN SUBJECTS WITH ADVANCED OR METASTATIC SQUAMOUS CELL (SQ) NON-SMALL CELL LUNG CANCER (NSCLC) WHO HAVE RECEIVED AT LEAST ONE PRIOR SYSTEMIC REGIMEN FOR THE TREATMENT OF STAGE IIIB/IV SQNSCLC: