Diagnostic Performance of PSMA-Targeted 18F-DCFPyL PET/CT in Men with Biochemically Recurrent Prostate Cancer: Results from the Phase 3, Multicenter CONDOR Study

38 Background: Currently available imaging modalities are inadequate in reliably localizing or determining the extent of biochemically recurrent (BCR) prostate cancer (PCa), especially in men with low prostate-specific antigen (PSA) levels. Identifying occult disease in men with BCR is critical for treatment planning. Thus, there is a clear need for improved imaging diagnostics for patients with recurrent PCa. 18F-DCFPyL is a novel PET agent for imaging PCa that binds selectively with high affinity to the cell surface protein prostate-specific membrane antigen (PSMA). Methods: Men ≥18 years of age with a rising PSA after definitive PCa therapy and negative or equivocal imaging were enrolled. A single ~9 mCi (333 MBq) dose of 18F-DCFPyL was administered followed by PET/CT from mid-thigh through skull vertex 1-2 hours later. The primary endpoint of this study was the correct localization rate (CLR). CLR is defined as the percentage of patients with a one-to-one correspondence between localization of at least one lesion identified by 18F-DCFPyL PET/CT and a composite standard of truth (SOT). SOT was determined by two central readers and included either histopathology or another standard imaging modality (i.e., fluciclovine-PET/CT, CT/MRI, bone scan) or alternatively, by a post-treatment PSA change for irradiated lesions. The trial was deemed a success if the lower bound of the 95% confidence interval for CLR exceeded 20% for two of three independent, blinded 18F-DCFPyL PET/CT reviewers. Results: 208 men with a median baseline PSA of 0.8 ng/mL (range: 0.2 - 98.4 ng/mL) underwent 18F-DCFPyL PET/CT. A total of 59% to 66% of subjects had at least one lesion detected by 18F-DCFPyL PET/CT by the three blinded independent readers. Among these patients, CLR of 84.8%-87.0% was observed (lower bound of 95% CI: 77.8%-80.4%). A single serious adverse event (AE) was reported as related to study drug (hypersensitivity). The most common AE reported was headache in four patients (1.9%). Conclusions: 18F-DCFPyL PET/CT achieved its primary endpoint with a CLR of up to 87% in localizing recurrent PCa in men with negative or equivocal baseline imaging. These data demonstrate the strong diagnostic performance of PSMA-targeted 18F-DCFPyL PET/CT and support its use to inform treatment choices in men with recurrent PCa. ClinicalTrials.gov identifier NCT03739684

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