18F-Sodium fluoride PET/CT predicts overall survival in patients with advanced genitourinary malignancies treated with cabozantinib and nivolumab with or without ipilimumab

Abstract

PurposeWe evaluated the prognostic value of 18F-sodium fluoride (NaF) PET/CT in patients with urological malignancies treated with cabozantinib and nivolumab with or without ipilimumab.MethodsWe prospectively recruited patients with advanced urological malignancies into a phase I trial of cabozantinib plus nivolumab with or without ipilimumab. NaF PET/CT scans were performed pre- and 8\xa0weeks post-treatment. We measured the total volume of fluoride avid bone (FTV) using a standardized uptake value (SUV) threshold of 10. We used Kaplan-Meier analysis to predict the overall survival (OS) of patients in terms of SUVmax, FTV, total lesion fluoride (TLF) uptake at baseline and 8\xa0weeks post-treatment, and percent change in FTV and TLF.ResultOf 111 patients who underwent NaF PET/CT, 30 had bone metastases at baseline. Four of the 30 patients survived for the duration of the study period. OS ranged from 0.23 to 34\xa0months (m) (median 6.0\xa0m). The baseline FTV of all 30 patients ranged from 9.6 to 1570\xa0ml (median 439\xa0ml). The FTV 8\xa0weeks post-treatment was 56–6296\xa0ml (median 448\xa0ml) from 19 available patients. Patients with higher TLF at baseline had shorter OS than patients with lower TLF (3.4 vs 14\xa0m; p\u2009=\u20090.022). Patients with higher SUVmax at follow-up had shorter OS than patients with lower SUVmax (5.6 vs 24\xa0m; p\u2009=\u20090.010). However, FTV and TLF 8\xa0weeks post-treatment did not show a significant difference between groups (5.6 vs 17\xa0m; p\u2009=\u20090.49), and the percent changes in FTV (12 vs 14\xa0m; p\u2009=\u20090.49) and TLF (5.6 vs 17\xa0m; p\u2009=\u20090.54) also were not significant.ConclusionHigher TLF at baseline and higher SUVmax at follow-up NaF PET/CT corresponded with shorter survival in patients with bone metastases from urological malignancies who underwent treatment. NaF PET/CT may be a useful predictor of OS in this population.