(UroToday.com) The 2022 GU ASCO Annual meeting included a urothelial carcinoma session highlighting work from Dr. Nicholas Simon and colleagues presenting results assessing the association of FDG PET/CT and NaF PET/CT with survival outcomes in patients with metastatic genitourinary malignancies treated with cabozantinib + nivolumab +/- ipilimumab. FDG PET/CT is widely used to assess for tumor burden, and NaF PET/CT is increasingly being used to assess osseous lesions. The aim of this study was to determine the association of functional imaging parameters obtained on FDG PET/CT and NaF PET/CT with OS for patients with metastatic genitourinary malignancies treated on a phase I study with cabozantinib + nivolumab +/- ipilimumab.
Patients on this phase I study underwent sequential (1-hour apart) FDG PET/CT and NaF PET/CT imaging at baseline and at first-restaging (8 weeks follow up). Scan semi-quantitative parameters measures included: maximum standardized uptake value (SUVmax), metabolic tumor volume, and total lesion glycolysis for FDG and metabolic tumor volume for NaF. Total lesion number was captured for all scans. The association of imaging parameters and survival was determined with Kaplan-Meier curves. Baseline values and percent change values were calculated.
There were 81 patients included in the analysis, including 957 FDG PET/CT and 414 NaF PET/CT lesions. Among these patients, 67 (83%) were males and the median age was 63 (range 25-86); Histologically, 30 patients had urothelial carcinoma, 15 clear cell renal cell carcinoma, 9 germ cell tumors, 8 urachal/adenocarcinoma, 8 prostate cancer, 3 penile cancer, 3 squamous cell carcinoma, 3 renal medullary carcinoma, and 2 small cell (1 bladder, 1 prostate). All 81 had a baseline FDG PET scan, 78 patients received baseline NaF PET scans; 66 received both FDG PET and NaF PET baseline and follow up scans. Among the 957 total lesions detected on FDG PET across all histologies, this included 87 patients with metastasis to the (9%), 252 to the lung (26%), 152 to the bone (16%), 411 to the lymph node (43%), and 55 to other visceral metastases (6%):
The strongest association for OS was:
- Low vs high baseline FDG metabolic tumor volume: 31 vs 11 months, p = 0.0002
- Total lesion glycolysis: 30 vs 11 months, p = 0.0004
- Lesion number: 49 vs 15 months, p = 0.0005
- SUVmax: 25 vs 12 months, p = 0.025
- FDG lesion number decrease or no change vs increase: 24 vs 12 months, p = 0.0068
- Low vs high baseline NaF metabolic tumor volume: 26 vs 16 months, p = 0.007
- Lesion number: 26 vs 16 months, p = 0.007)
A multivariable Cox analysis demonstrated that baseline FDG metabolic tumor volume (HR 2.87, 95% CI 1.62-5.08) and FDG lesion number percent change (HR 2.71, 95% CI 1.40-5.24) were jointly associated with OS.
Dr. Simon concluded his presentation of the association of FDG PET/CT and NaF PET/CT with survival outcomes in patients with metastatic genitourinary malignancies treated with cabozantinib + nivolumab +/- ipilimumab with the following take-home messages:
- More aggressive histologies were shown to have higher values for the volumetric and semi-quantitative parameters
- Baseline functional imaging parameters and percent change seen on follow imaging with FDG PET and NaF PET are prognostic in metastatic genitourinary patients treated with cabozantinib + nivolumab +/- ipilimumab
- Future directions include examining the relationship between circulating biomarkers (CTCs and ctDNA) and functional imaging parameters to better predict outcome
Co-Authors: Katherine Lei, Nicholas Peter Verdini, Jeffrey Lin, Andy Vega, Scot Anthony Niglio, Amir Mortazavi, Sumanta K. Pal, Jeffrey Kempf, Murray Becker, Michael V. Knopp, Chadwick Wright, Alex Jung, Peter L. Choyke, Seth M. Steinberg, Esther Mena, Liza Lindenberg, Andrea B. Apolo
Written by: Zachary Klaassen, MD, MSc – Urologic Oncologist, Assistant Professor of Urology, Georgia Cancer Center, Augusta University/Medical College of Georgia, @zklaassen_md on Twitter during the 2022 American Society of Clinical Oncology Genitourinary (ASCO GU) Cancers Symposium, Thursday Feb 17 – Saturday Feb 19, 2022