Prostate cancer imaging agent meets one of two study endpoints
- A positron emission tomography imaging agent developed by Progenics Pharmaceuticals to improve prostate cancer detection met one of two primary endpoints in a Phase 2/3 clinical trial and will continue to be studied in a Phase 3 trial that will launch by year-end, the company said.
- The prostate specific membrane antigen (PSMA)-targeted imaging agent, called PyL, showed a high specificity to detect prostate cancer in pelvic lymph nodes, to meet one co-primary endpoint. Results for a sensitivity measure did not meet the second primary endpoint. Overall, however, the study showed strong positive predictive value and supports continued development, the New York-based company said.
- Progenics said it has discussed its Phase 3 trial design with FDA and will use PPV parameters in biochemical recurrent prostate cancer patients as this basis for the study’s primary endpoint.
The Phase 2/3 study is Progenics' second clinical trial for a prostate cancer imaging agent to show mixed results in as many months. In September, the company announced its PSMA-targeted 1404 imaging agent met a primary endpoint for specificity but missed a primary goal measuring sensitivity in a Phase 3 clinical trial. Progenics said it would review the data before determining the development path for the 1404 agent going forward.
With PyL, however, Progenics appears more confident of a successful Phase 3 outcome. Vivien Wong, the company's executive vice president of development, said both positive and negative predictive values are increasingly considered more relevant indicators of clinical utility.
Jefferies analyst Biren Amin, in a research report, said PPV was the primary endpoint in the study that formed the basis for FDA's approval of Axumin, developed by U.K.-based Blue Earth Diagnostics, for use in PET imaging of recurrent prostate cancer patients. Axumin generated sales of about $50 million in its first full year of launch, ended in March 2018, Amin said.
The Osprey study looked at PyL’s ability to detect prostate cancer in the pelvic lymph nodes of patients with high-risk, locally advanced prostate cancer and to detect distant metastases in patients with metastatic or recurrent prostate cancer. A total of 385 patients were studied.
The two primary endpoints focused on the first group of patients, with localized pelvic disease. High specificity of 96-99% among three blinded independent readers exceeded the target of 80% in this group. On the second primary endpoint, the lower end of the sensitivity rate of 31-42% missed the 40% goal. PPV was for pelvic lymph node detection was 78-91%, while negative predictive value was 81-84%.
Among metastatic patients in the second cohort, sensitivity of 93-99% and PPV of 81-88% were seen.
PyL showed high sensitivity in detecting distant metastatic prostate cancer lesions and high specificity in confirming the absence of pelvic lymph node disease, the company emphasized.
"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," Michael Morris, associate professor at Memorial Sloan Kettering and a lead investigator of the trial, said in a press release.