Study of Diagnostic Performance of [18F]CTT1057 in BCR

The current study aimed at evaluating the diagnostic performance of \[18F\]CTT1057 as a PET imaging agent for detection and localization of Prostate specific membrane antigen (PSMA) positivity in patients diagnosed of biochemical recurrence of prostate cancer (PCa), using a composite truth standard. Approximately 190 participants were to be enrolled to ensure at least 152 participants were evaluable (i.e. have both an evaluable \[18F\]CTT1057 Positron emission tomography/Computed Tomography (PET/CT) scan imaging and at least one evaluable Composite Truth Standard (CTS) assessment and had not received any prohibited systemic antineoplastic therapy before the completion of PET/CTs and CTS procedures, which were required for the calculation of the co-primary endpoints.

This was a prospective, open-label, multi center, single-arm Phase III study to evaluate the diagnostic performance of \[18F\]CTT1057 as a PET imaging agent for detection and localization of PSMA positive tumors in PCa patients diagnosed with biochemical recurrence (BCR) after initial definitive therapy with either radical prostatectomy (RP) or curative intent radiation therapy (RT), using a CTS as reference. The CTS to be used as reference were hierarchical in nature, with 3 levels of Standard of Truth (SoT) procedures, that were applied as follows: CTS Level 1: Histopathology if available for the lesion (from prospective biopsy or salvage surgery performed within 8 weeks after the \[18F\]CTT1057 PET/CT scan); OR in case that histopathology was not available for a lesion, inconclusive or negative (for biopsy only). CTS Level 2: Imaging diagnostic procedures performed on each patient as clinically indicated per SoC, which included at least a high resolution CT scan with contrast and a \[68Ga\]Ga-PSMA-11 PET/CT) performed within 8 weeks (either before or after) the \[18F\]CTT1057 PET/CT scan. Three-month follow-up imaging (from baseline) were also be used as part of the CTS level 2 in cases where it is clinically required for the diagnosis of particular lesion(s); OR if neither of the two above were feasible or deemed appropriate or they were inconclusive. CTS Level 3: 50% or greater decline in PSA following radiation therapy (as long as no concomitant androgen deprivation therapy (ADT) was given) as per Prostate Cancer Working Group 3 (PCWG3) criteria. All participants underwent 2 PET/CT scans: one with the investigational agent \[18F\]CTT1057 and another with \[68Ga\]Ga-PSMA-11 (as a component of the CTS Level 2 and for a secondary endpoint of assessment of concordance between the 2 PET/CT scans for detection of lesions). The 2 PET imaging procedures were performed at least 14 days apart, and the PET/CT scan sequence for each participant was assigned at random in a 1:1 ratio.