4. Patients with isolated lung parenchymal recurrent/persistent NSCLC (histology as defined in eligibility criterion 1) after prior definitive surgery or radiotherapy/chemotherapy, when the lesion or lesions are suitable for SABR, are also eligible. Patients with a single metastatic focus in the lung parenchyma with no other lesions are also eligible, because this presentation is challenging to distinguish from recurrent disease. Recurrent disease can be in the same lobe or a different lobe but should not invade critical structures (esophagus, brachial plexus, major vessels, heart, spinal cord); should not involve any lymph node; and should not include any other suspicious lesions in the lung or any other locations. Any prior therapy (surgery, radiotherapy, or systemic) must have been completed at least 12 weeks before administration of the study drug.