Sarah Verhoeff

46 Chapter 3 Procedures [18F]FDG and [89Zr]Zr-DFO-girentuximab PET/CT At baseline, patients underwent whole-body [18F]FDG and [89Zr]Zr-DFO-girentuximab PET/ CT. The [18F]FDG PET/CTs were performed according to European Association of Nuclear Medicine (EANM) guidelines version 1.025. The [89Zr]Zr-DFO-girentuximab imaging procedure was harmonized between participating, EARL-accredited centers. Patients underwent [89Zr]ZrDFO-girentuximab PET/CT 4 days after intravenous (IV) injection of 37 MBq [89Zr]Zr-DFOgirentuximab (protein dose 5 mg). Details on acquisition and reconstruction protocols, conjugation, radiolabeling and quality control of [89Zr]Zr-DFO-girentuximab were described previously26. The [18F]FDG PET/CTs were assessed by local nuclear physicians according to standard clinical practice. The [89Zr]Zr-DFO-girentuximab PET/CTs were assessed by three independent nuclear physicians in a central reviewing system, to ensure reproducible lesion detection and inter-observer agreement. The medical oncologist did not have access to the PET/CT images as these results were saved outside of the Electronic Patient Dossier. The nuclear medicine physicians were allowed to communicate findings that required (local) interventions. Volumes-of-interest were defined using CT-images co-registered to the PET/CT, drawn manually on the [18F]FDG and [89Zr]Zr-DFO-girentuximab PET-images based on tracer accumulation exceeding mediastinal blood pool. Standardized uptake values (SUVmax) were measured using Inveon Research Workplace software (IRW, version 4.1). The geometric mean (gm) SUVmax values per patient were calculated for RECIST-evaluable lesions with visual tracer-uptake. The volumetric parameters metabolic tumor volume (MTV) and total lesion glycolysis (TLG) were determined for [18F]FDG PET/CT. Contrast-enhanced (ce)CT scan Patients underwent ceCT of the chest, abdomen and pelvis at baseline, at 2,4,6, 9 and 12 months and every 4 months thereafter. To explore clinical usefulness of WW, PD was adapted to ‘disease progression warranting systemic treatment’. Therefore, PD was defined according to Response Evaluation Criteria in Solid Tumors (RECIST) 1.127, except for: • an increase of >20% of sum of diameters of target lesions, not exceeding an absolute increase of 10mm; • a new lesion in lung or bones in patients with limited (<5 lesions) baseline disease located in lung and/or bones; • progression that warrants local therapy but not systemic therapy. Outcomes The primary aim was to assess the predictive value of [18F]FDG and/or [89Zr]Zr-DFO-girentuximab PET/CT to ceCT to predict time to disease progression warranting systemic treatment, also split into extremes of rapid progression (<2 months) and indolent disease (>12 months) in patients with good or intermediate prognosis mccRCC. Time to disease progression was defined as the time