Pyl Imaging Agent Accurately Detects Recurrent Prostate Cancer Lesions

Progenics Pharmaceuticals’ PyL, a new imaging agent for positron emission tomography (PET) scans, can accurately detect the location of recurrent prostate cancer lesions, according to data from the Phase 3 CONDOR clinical trial.

“There is a need for improved diagnostics for prostate cancer to replace conventional imaging tests that have limited performance characteristics, especially in men with biochemical recurrence of their disease,” said Barry Siegel, MD, CONDOR’s principal investigator at the Mallinckrodt Institute of Radiology at Washington University School of Medicine clinical site.

PyL (18F-DCFPyl) is a tracing agent composed of DCFPyL, a small molecule that specifically targets the prostate specific membrane antigen (PSMA) protein — present at high levels in prostate cancer cells — coupled with a radioactive compound labelled with fluorine 18. After PyL is injected intravenously into the patient, it travels through the blood and accumulates at prostate cancer sites, making them “light up” during PET scans. PyL has the potential to allow clinicians to detect very small lesions that are currently missed with conventional imaging methods, so can they determine if the disease has returned or spread to distant organs and adjust treatment plans accordingly.

The open-label CONDOR study (NCT03739684) evaluated whether PyL could safely, successfully, and accurately detect new prostate cancer lesions in 208 men suspected of prostate cancer relapse. These suspicions, which were based on biochemical relapse — rising levels of prostate-specific antigen (PSA), a biomarker of the disease — were accompanied by negative or ambiguous findings on conventional imaging scans.

Participants were recruited, dosed, and imaged with PyL at 14 sites in the U.S. and Canada. CONDOR’s primary goal was to assess the predictive value of PyL in detecting the right location of new cancer lesions that confirmed the disease had returned. For that, three blinded, independent researchers compared the results of PyL PET scans with those of confirmatory biopsy or surgery, conventional imaging, and/or changes in PSA levels following radiation therapy of PyL-suspected lesions, performed within 60 days after PyL imaging. The study’s secondary goal was determining the percentage of patients whose treatment plan was changed based on PyL imaging results.

Results showed that the trial met its primary goal, with PyL imaging detecting at least one posteriorly confirmed new lesion in 84.8% to 87% of the cases. This exceeded by far the 20% threshold established by the FDA “for the trial to be deemed a success,” reflecting “the impactful clinical utility of PyL imaging.”

As far as safety, the imaging agent was well-tolerated, consistent with data from the previous Phase 2/3 OSPREY clinical trial (NCT02981368). The most frequently reported adverse side effect (in 1.9% of patients) was headache, and one man had a serious immune reaction (hypersensitivity) to PyL.

“The high positive predictive value demonstrated in this study reflects the clinical utility of PSMA-targeted PET imaging agents providing actionable information to physicians to guide treatment plans and improve disease management of one of the most prevalent cancers in the U.S.,” Siegel said.

“The positive results of our Phase 3 CONDOR trial reinforce our belief in the potential of PyL to enable better physician treatment decisions and, ultimately, improve patient outcomes,” David Mims, Progenics’ interim CEO, said in a press release. The company plans to submit a new drug application for PyL to the U.S. Food and Drug Administration in the second half of this year, according to Mims.

Material cited above was received on January 13th in the Prostate Cancer News Today Weekly Digest to which I recommend a subscription.

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