CTLA4 and cancer: reported a modest 13% response rate in a phase I study of SBRT (dose varied by anatomic site) to two to four metastases followed by pembrolizumab in heavily pretreated patients with a variety of primary cancers [18], while Hammers, et al. reported an encouraging response rate of 56% in patients with metastatic clear cell renal cell carcinoma receiving dual anti-PD-1/cytotoxic T-lymphocyte-associated protein 4 with nivolumab/ipilimumab and concurrent, higher dose SBRT (10Gyx5) to only one or two metastases [19].