PSMA PET/CT alters treatment approach in 66% of patients with recurrent prostate cancer

Ur Metser, MD

The use of ¹⁸F-DCFPyL PSMA PET/CT redirected the treatment approach in 66% of patients with prostate cancer enrolled in a multicenter trial, according to findings presented during the 2020 Society of Nuclear Medicine and Molecular Imaging Virtual Annual Meeting.¹

The prospective multicenter trial included 410 men with biochemical failure following primary therapy. Standard imaging with CT and bone scintigraphy showed limited or no disease. Among the patients with negative CT and bone scan scintigraphy was negative, PSMA PET/CT detected disease in over 50% of patients. And in patients in whom limited metastases were detected, PSMA PET/CT identified additional metastatic locations in close to two-thirds of men.

Based on the new information revealed by PSMA PET/CT, the treatment strategy was changed in two-thirds of patients. The changes in patient management that occurred most frequently were a shift from observation or systemic therapy to surgery or radiation, or adding nodal-directed therapy to radiation or salvage surgery.

“The identification of extent of recurrence and specific sites of recurrence is crucial in determining the most appropriate mode of therapy for these men. Findings from this study add to the body of evidence on the utility of PSMA PET in the management of prostate cancer patients,” lead study investigator Ur Metser, MD, professor of radiology at the University of Toronto in Ontario, Canada, stated in a press release.

“At this time, PSMA PET remains investigational in North American jurisdictions. Evidence generated from this study will help in seeking regulatory approvals to make molecular imaging with ¹⁸F-DCFPyL widely available and will pave the way for clinical studies that incorporate PSMA PET as a treatment planning tool to assess ultimate impact on patient outcomes,” added Metser.

Significant research with PSMA PET is rapidly emerging in the prostate cancer field.Pivotal data for the investigational fluorinated PSMA-targeted PET imaging agent PyL™ (¹⁸F-DCFPyL) were presented during the 2020 American Society of Clinical Oncology Virtual Scientific Program. The findings came from the prospective, multicenter, open-label, phase 3 CONDOR trial, which included 208 patients with biochemical recurrence of prostate cancer. The men had received baseline imaging with standard PET, CT/MR, and/or bone scan. Baseline imaging with these modalities was considered to be “uninformative.”²

The primary end point of the trial was correct localization rate (CLR), which is “based on positive predictive value, defined as the percentage of patients with a one-to-one correspondence between localization of at least one lesion identified on PyL and a composite truth standard comprised of histopathology, conventional imaging and/or a ≥ 50% decline in PSA levels following radiation therapy.”² The study achieved this end point, with a CLR of 84.8% to 87.0% among the 3 blinded independent readers. The lower bound of the confidence intervals ranged from 77.8% to 80.4%.

The PyL results changed the treatment course for 63.9% of the patients. The most common alterations to patient management included planned treatment to observation, salvage local therapy to systemic therapy, noncurative systemic therapy to salvage local therapy, and observation to initiating therapy.

References

1. Metser U Zukotynski K, Liu W, et al. Preliminary results of a prospective, multicenter trial assessing the impact of ¹⁸F-DCFPyL-PET/CT on the management of patients with recurrent prostate cancer. Presented during Society of Nuclear Medicine and Molecular Imaging’s 2020 Virtual Annual Meeting. July 11-14, 2020. Abstract 40.

2. Progenics to Present Results from the Phase 3 CONDOR Trial of PyL™ (¹⁸F-DCFPyL) in Prostate Cancer at the American Society of Clinical Oncology 2020 Virtual Scientific Program. Published May 18, 2020. https://bit.ly/3gYDZh5. Accessed July 13, 2020.