Results of Phase 2/3 Trial of PSMA PET Imaging Agent PyL for the Detection of Prostate Cancer Spread

Data from the phase 2/3 OSPREY 2301 Study has shown that the PSMA-targeted small molecule PET imaging agent (PyL (18F-DCFPyL) designed to better visualize prostate cancer outside of the gland demonstrated high sensitivity and reliably in detecting distant metastatic prostate cancer lesions and also a high specificity in confirming the absence of pelvic lymph nodes. 

In the study, PyL demonstrated strong positive predictive values and negative predictive value of PyL imaging in these disease settings indicate its potential high clinical utility.

Dr. Michael Morris, Associate Professor at Memorial Sloan Kettering, and a lead investigator of the trial said “these are highly encouraging results in a large, well-controlled and rigorous trial showing PyL has excellent positive and negative predictive value in assessing the distribution of disease in men with high-risk prostate cancer. Furthermore, in men intended to go to surgery, the specificity of PyL was exceedingly good. Taken together, a PyL PET avid lesion is a reliable reflection of histologically proven disease and may provide additional important information to men with prostate cancer and their doctors. That information may provide important guidance in the decision-making for their treatment.”

The trial examined the diagnostic performance of the PSMA-targeted PET imaging agent, PyL, to detect prostate cancer in pelvic lymph nodes in men with high risk locally advanced prostate cancer (Cohort A) and distant metastases in men with metastatic or recurrent (Cohort B) prostate cancer. 

The OSPREY study examined 385 men with either high-risk locally advanced prostate cancer (268) or metastatic or recurrent prostate cancer (117). The study’s co-primary endpoints were the assessment of specificity and sensitivity of PyL PET imaging in Cohort A to detect prostate cancer in pelvic lymph nodes in patients scheduled to undergo radical prostatectomy with extended pelvic lymph node dissection. Secondary endpoints for Cohort A were positive predictive value and negative predictive value.  The study also evaluated several key secondary endpoints in Cohort B, including the sensitivity and positive predictive value of PyL PET imaging in detecting metastatic prostate cancer in men where lesion biopsies (bone, soft tissues, lymph nodes other than pelvic lymph nodes) were feasible.

The investigation contrast, 18F‐DCFPyL well tolerated by the men. A total of 27 (7%) men experienced at least one treatment-related adverse event.  There were no serious adverse events related to study drug.  The most frequent drug-related events included dysgeusia (a distortion of the sense of taste)  (2.1%) and headache (2.1%).


-PyL is highly sensitive (93-99%) in reliably detecting metastatic prostate cancer lesions and highly specific (96-99%) in confirming the absence of pelvic lymph node disease-

-Study data highlights the strong positive predictive values of PyL to detect prostate cancer in pelvic lymph nodes and metastatic lesions and supports the continued development of PyL- 

-Phase 3 trial to commence by year end-