Ito K, et al. - In 60 patients with metastatic malignant melanoma treated with ipilimumab, researchers assessed the correlation between tumor response on ¹⁸F-FDG PET/CT and prognosis. According to PERCIST5, tumor response was evaluated by the change in the sum of SULpeak (voxels with the highest average SUL [SUV normalized to lean body mass]) of up to 5 lesions. Findings revealed that tumor response according to PERCIST was related to overall survival in patients with metastatic melanoma treated with ipilimumab. Investigators suggested that the appearance of new lesions should not define progressive metabolic disease (PMD), but rather an increase in the sum of SULpeak.