18F-DCFPyL Could Become a Key Diagnostic Tool for Biochemical Recurrence in Prostate Cancer

Andrei Iagaru, MD

¹⁸F-DCFPyL, a PET prostate specific membrane antigen (PSMA) targeting agent, demonstrated statistically significant potential in detecting biochemical recurrence in men with prostate cancer, according to a single-center study presented during the 2021 American Urological Association Annual Meeting.

“It is well known that prostate cancer is No. 1 as far as new cases in men in the United States and second only after lung cancer as far as estimated deaths for the same year. So, we need better imaging tools,” Andrei Iagaru, MD, professor of radiology-nuclear medicine, chief, Division of Nuclear Medicine and Molecular Imaging, Stanford Health Care, said during a virtual presentation at the meeting.

In total, 242 patients were prospectively enrolled with biochemical recurrence after primary definitive treatment with prostatectomy (72%), radiotherapy (28%), or both (25%).

In total, 131 patients (54%) had a Gleason score of 7.

Among those who underwent radical prostatectomy and radiation therapy, respectively, the median times to first BCR were 34 months (range, 3-240) and 48 months (range, 3-192). Mean 18F-DCFPyL activity was 343.0±25.2 MBq, and time to acquisition after administration was 77.3±13.2 minutes.

The detection rates of 18F-DCFPyL based on PSA level (ng/mL) in patients who experienced BCR were as follows: PSA <0.5, 65%; 0.5≤ PSA <1, 74%; 1≤ PSA <2, 90%; 2 ≤ PSA < 5, 93%; and PSA ≥ 5, 96%. Across all PSA levels, the detection rate was 81%. Among patients who underwent prostatectomy, the corresponding detection rates of 18F-DCFPyL by the same PSA ranges, respectively, were 65%, 73%, 90%, 96%, and 100%. Across all PSA levels the detection rate post-prostatectomy was 80%. And after radiotherapy, the corresponding detection rates were 100%, 100%, 100%, 88%, and 94%, respectively, with a detection rate of 92% across all PSA levels.

Further, researchers evaluated the detection rate of 18F-DCFPyL after prostatectomy based on PSA doubling time. After the first 3 months, 90% showed a positive scan, compared with 86% from months 3 through 6, 75% from months 6 through 12, and 61% for month 12 and beyond.

“Of course, the more aggressive the tumor, the lower the doubling time, the higher the positivity rate. And similarly, if we look at Gleason score, the more aggressive the tumor, the higher the percentage of positivity rate,” Iagaru said. “Now, whereas this positivity was just not unexpected, that number is higher in the prostate gland after radiation therapy. But then once you get into lymph nodes, and bones and other organs, the numbers are pretty similar between the 2 groups.”

Following 18F-DCFPyL PET/CT, 46% on targeted radiotherapy, 28% on androgen-deprivation therapy, 8% on surveillance, and 18% considered “other,” changed management of their disease after a positive scan, compared with 24%, 7%, and 69%, respectively, who changed treatment management after a negative scan.

“18F-DCFPyL PET/CT holds great potential to be a ‘one-stop shop’ diagnostic tool in the work-up of BCR prostate cancer to identify possible extra-pelvic oligometastases for locally targeted therapy,” the researchers concluded in their abstract.

Reference

1. Song H, Nguyen J, Moradi F, et al. Prospective Evaluation of 18F-DCFPyL PET/CT in Biochemically Recurrent Prostate Cancer: analysis of 18F-DCFPyL uptake in possible extra-pelvic oligometastases.Presented at: 2021 American Urologic Association Annual Meeting; September 10-13, 2021; Virtual. Abstract LBA02-06.