Blood Tests Predict Effectiveness of Hormonal Therapies
A multi-institutional group of clinical researchers, led by the Duke Cancer Institute’s Andrew Armstrong, MD, McS, FACP, published a new report this month in the Journal of Clinical Oncology [NOTE: Link to publication will be available at 4 p.m.], that describes results from the PROPHECY study, which prospectively compared two blood tests to assess how well they predicted the effectiveness of hormonal therapy in men with metastatic prostate cancer.
The blood tests, which are called “liquid biopsies,” detect androgen receptor splice variant-7 (AR-V7) in circulating prostate cancer cells. The circulating tumor cell (CTC) tests are simple, non-invasive blood draws, and provide results in just a few days, identifying cells that shed from the tumor or metastasis into circulation.
The PROPHECY study, presented at the American Society of Clinical Oncology Annual Meeting in 2018, was a multicenter, prospective study of 118 men across five medical centers with metastatic prostate cancer who had disease progression despite hormonal therapy and who were starting abiraterone acetate or enzalutamide treatment. It compared two current assays in a blinded fashion, in which investigators were blinded to the CTC results and laboratories were blinded to the clinical results. The two tests are called the EPIC AR-V7 Nuclear Protein CTC assay (now called the Oncotype DX® AR-V7 Nucleus Detect™ test), and the Johns Hopkins AR-V7 Adnatest assay. Both tests measure AR-V7 in different ways using either protein or mRNA, and neither has yet been approved by the FDA.
“We have therapies to treat recurrent, metastatic prostate cancer, but they don’t work on everyone, and cross-resistance between newer hormonal therapies is a major emerging problem in our field,” explained Armstrong. “It’s important to know which men are more likely to benefit from further hormonal therapies as well as to identify those men with little chance of benefiting in order to rapidly provide alternative, more effective therapies and or to develop new therapies for these men.”