Impact of PSMA-targeted imaging with 18F-DCFPyL-PET/CT on clinical management of patients (pts) with biochemically recurrent (BCR) prostate cancer (PCa): Results from a phase III, prospective, multicenter study (CONDOR).

Abstract

5501 Background: Current imaging modalities are inadequate for localizing and characterizing occult disease in men with BCR PCa, particularly in pts with low PSAs (<2 ng/mL). There is a need for improved diagnostic imaging to better inform treatment planning. 18F-DCFPyL (PyL) is a novel PET imaging agent that binds selectively with high affinity to PSMA, which is overexpressed in PCa cells. Methods: Men ≥18 years- with rising PSA after definitive therapy and negative or equivocal standard of care imaging (e.g., CT/MRI, bone scintigraphy) were enrolled. A single 9 mCi (333 MBq) ± 20% dose of PyL was injected, followed by PET/CT 1-2 hours later. Primary endpoint was correct localization rate (CLR), defined as percentage of pts with a 1:1 correspondence between at least one lesion identified by PyL-PET/CT and the composite standard of truth: pathology, correlative imaging, or PSA response. The trial was successful if the lower bound of the 95% confidence interval (LLCI) for CLR exceeded 20% for two of three independent, blinded central PyL-PET/CT reviewers. The secondary endpoint, impact of PyL-PET/CT on clinical management of pts was based on the treating physician’s documented clinical plans before and after PyL-PET/CT. Results: 208 men (median PSA 0.8 [0.2 - 98.4] ng/mL) underwent PyL PET/CT. The study achieved its primary endpoint: CLR of 84.8% to 87.0% among the three PyL-PET/CT readers; the LLCI for CLR by all three reviewers was >77%. Here we report the clinical impact. Based on local radiology assessment, PSMA-avid lesion(s) were identified in 69.3% (142/208) of pts. 63.9% (131/205) had a change in intended management after PyL-PET/CT, of which 78.6% (103/131) were attributable to positive PyL finding(s) and 21.4% (28/131) to negative PyL scans. Changes included: salvage local therapy to systemic therapy (n=58); observation before initiating therapy (n=49); noncurative systemic therapy to salvage local therapy (n=43); and planned treatment to observation (n=9). PyL was well tolerated with one drug-related SAE (hypersensitivity) and the most common AE being headache (n=4; 1.9%). Conclusions: PSMA-targeted PyL-PET/CT detected and localized occult disease in most men with BCR presenting with negative or equivocal conventional imaging. PyL-PET/CT led to changed management plans in the majority of pts, thus providing evidence that clinicians find PSMA PET imaging useful in men with recurrent or suspected metastatic PCa. Clinical trial information: NCT03739684 .