- Has had restaging imaging after initiation of immunotherapy, at least 4 weeks after pre-immunotherapy baseline imaging; computed tomography (CT) or positron emission tomography (PET)/CT of at least chest/upper abdomen must be performed within 4 weeks prior to registration; for patients with history of brain metastases, brain magnetic resonance imaging (MRI) or CT is required within 4 weeks of registration; for other patients brain MRI or CT is required within 12 weeks of registration