Unlike in our group, patients in their study were mostly treated with the CTLA-4 inhibitor ipilimumab and tumor response was assessed according to RECIST, immune-related response criteria, PERCIST and EORTC criteria.12 In another study by Anderson et al., 18F-FDG-PET/CT was performed after a single dose of pembrolizumab, at a median of 7 days (range: 3–21 days) after the start of treatment. Here, CTLA4 is linked to neoplasm.