CONDOR: 18F-DCFPyL PET diagnoses biochemically recurrent prostate cancer
medwireNews: Positron-emission tomography (PET) using the novel prostate-specific membrane antigen (PSMA) targeted 18F-DCFPyL tracer shows “excellent diagnostic performance” in men with biochemically recurrent prostate cancer, researchers report.
Speaking at the virtual 2020 ASCO Annual Meeting, Michael Morris, from the Memorial Sloan Kettering Cancer Center in New York, USA, said that 18F-DCFPyL PET “clearly showed superiority to the standard imaging these men received as part of their local workups.”
He added that “the results demonstrated that actionable information was furnished to clinicians in order to make clinically significant decisions.”
The CONDOR trial included 208 men with rising prostate-specific antigen (PSA) levels (median 0.8 ng/mL) after definitive therapy for prostate cancer and negative or equivocal results on standard imaging such as computed tomography (CT), magnetic resonance imaging, or bone scintigraphy. They each received a single 9 mCi (333 MBq) dose of 18F-DCFPyL, followed by PET/CT 1 to 2 hours later.
The imaging results were reviewed by three readers and compared with a hierarchical gold standard of pathology, correlative imaging, or PSA response (according to which was available), which was used to calculate the correct localization rate (CLR).
Morris explained that the CLR “is essentially [a] positive predictive value with the added requirement of anatomical location matching for the lesions.”
The disease detection rate across the three readers ranged from 59.1% to 65.9%, while the CLR ranged from 84.8% to 87.0%.
And Morris pointed out that the lower limit of the 95% confidence interval for CLR “was well in excess of the 20% benchmark,” at 77.8–80.4%, indicating that the study met its primary endpoint.
Subanalyses by PSA level showed that the median CLR across the three readers ranged from 73.3% among men with a PSA below 0.5 ng/mL increasing to 96.4% among those with a PSA of 5 ng/mL or higher.
The CONDOR investigators also assessed how the 18F-DCFPyL imaging results impacted patient care. They found that 63.9% of patients had a change in intended management after their scan, with Morris stressing the importance of recognizing “the clinical significance of these changes.”
Indeed, 21.0% had their care goal changed from noncurative systemic therapy to salvage local therapy, 28.3% had a change from salvage local therapy to systemic therapy, 23.9% switched from observation to initiating therapy, and 4.4% went from planned treatment to observation.
Three patients experienced a treatment-related adverse event, including one case of hypersensitivity in a patient with a serious allergic history.
Morris concluded that CONDOR “demonstrated [the] excellent diagnostic performance of [18F-DCFPyL] PET in men with biochemically relapsed prostate cancer, even at very low PSA values.”
He added: “The CONDOR trial coupled with the OSPREY study has now established the performance characteristics of [18F-DCFPyL] across the full spectrum of prostate cancer.”
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