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.
Study sponsor and potential other locations can be found on ClinicalTrials.gov for NCT04838613.
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.
Lead OrganizationNovartis Pharmaceuticals Corporation