Epic Sciences, Inc. (Epic) today announced the publication of results from a multicenter prospective trial validating the biomarker AR-V7 (androgen receptor splice variant-7) as a predictor of resistance to anti-androgen therapy in men with metastatic castration-resistant prostate cancer (mCRPC). Data from the PROPHECY trial, published in the Journal of Clinical Oncology, demonstrate that detection of AR-V7 in circulating tumor cells (CTCs) in blood is predictive of whether men with mCRPC have become resistant to androgen-receptor signaling (ARS) inhibitors and have a low chance of benefit from further ARS therapy.
Many men with mCRPC live longer when treated with the potent androgen receptor (AR) pathway inhibitors enzalutamide and abiraterone, which are considered the standard of care. However, in patients previously treated with one round of AR therapy, response rates are low and progression-free survival (PFS) and overall survival (OS) times are short. Moreover, cross resistance between these agents is common, and clinical features alone are unable to identify tumors that are cross-resistant. Therefore, predictive biomarkers are urgently needed to permit physicians and patients to select the most optimal therapies.
In the paper entitled “Prospective multicenter validation of AR-V7 and hormone therapy resistance in prostate cancer: the PROPHECY study,” researchers led by Andrew J. Armstrong, M.D., ScM, FACP, Professor of Medicine, Surgery, Pharmacology and Cancer Biology; Director of Research, the Duke Cancer Institute Center for Prostate and Urologic Cancers, Divisions of Medical Oncology and Urology at Duke University, conducted this prospective, blinded clinical trial to validate the predictive significance of baseline CTC AR-V7 based on PFS as the primary endpoint, as well as OS, in 118 men with mCRPC undergoing ARS inhibitor therapy.
In the latest validation, the trial met its primary endpoint and the researchers concluded the detection of AR-V7 in CTCs by two blood-based assays, including the Epic Sciences CTC nuclear-specific AR-V7 protein assay, is independently associated with shorter PFS and OS in men with high-risk mCRPC taking either abiraterone or enzalutamide. Patients who tested AR-V7 positive had worse survival by all measures. For the Epic assay, the median PFS for AR-V7 positive versus AR-V7 negative patients was 3.1 versus 6.1 months, respectively. The median OS for AR-V7 positive versus AR-V7 negative patients was 8.4 versus 25.5 months, respectively. Additionally, no AR-V7 positive patients had a PSA or radiographic response to abiraterone or enzalutamide. The trial results indicate men with mCRPC who test positive for AR-V7 should be offered alternative, more effective treatments, such as taxane chemotherapy or a clinical trial of an investigational therapy.
The AR-V7-based test developed by Epic Sciences is now available to the estimated 50,000 men in the United States with advanced prostate cancer through Genomic Health’s commercial launch of the Oncotype DX® AR-V7 Nucleus Detect™ test and is now covered by Medicare.
“In this study, we demonstrate in a prospective, blinded manner that men with high-risk metastatic castration-resistant prostate cancer who are AR-V7 positive have little evidence of clinical benefit from abiraterone or enzalutamide, with short duration of overall and progression-free survival. Epic Sciences’ AR-V7 test may better inform the decision to pursue further ARS therapy prior to starting second line ARS treatment, rather than using these agents for a few months and then stopping if the treatment is ineffective,” said Dr. Armstrong.
Dr. Armstrong continued, “One of the unique aspects of this multicenter study was that laboratory investigators were blinded to the clinical results, and clinicians were blinded to the laboratory results, and that the definitions of a positive test for AR-V7 were defined in advance and thus prospectively validated. Having a reliable test that is associated strongly with a lack of clinical benefits to a therapy can help a patient and doctor pick a more effective therapy and not waste valuable time, resources and unnecessary toxicities from an ineffective, cross-resistant drug. Such information can enable oncologists to identify potentially life-extending treatments for these men with aggressive disease.”
Dr. Armstrong originally presented the top-line PROPHECY data in an oral presentation at the ASCO 2018 Annual Meeting.
“Demonstration in the PROPHECY trial of our AR-V7 test’s ability to predict which patients will not respond to a frequently utilized and important drug class is a tremendous achievement,” said Ryan Dittamore, Chief of Medical Innovation at Epic Sciences and co-author of the study. “This clinical evidence further supports the value of our liquid biopsy test in providing critical information for the clinical management of patients with advanced prostate cancer.”
The results from a second blinded, multi-center clinical utility study of the Epic AR-V7 test were published in JAMA Oncology in September 2018.
The PROPHECY study was supported by a grant from the Prostate Cancer Foundation and Movember as well as infrastructure support from the Department of Defense Prostate Cancer Clinical Trials Consortium (DOD PCCTC).
About the Oncotype DX® AR-V7 Nucleus Detect™ Test
Designed by Epic Sciences and based on results from multiple studies led by Memorial Sloan Kettering Cancer Center and Duke University, the Oncotype DX AR-V7 Nucleus Detect test is the first and only liquid biopsy test of its kind that can potentially prolong the lives of men with metastatic castration-resistant prostate cancer (mCRPC) by helping their physician identify the most effective treatment. Through a blood draw, the test detects AR-V7 protein in the nucleus of circulating tumor cells utilizing Epic Sciences’ No Cell Left Behind® platform to accurately identify patients who are resistant to androgen receptor (AR)-targeted therapies and who should instead switch to chemotherapy. The Oncotype DX AR-V7 Nucleus Detect test is performed by Epic Sciences at its centralized, CLIA-certified laboratory in San Diego and is offered exclusively by Genomic Health. To learn more about the Oncotype DX AR-V7 Nucleus Detest test, visit www.OncotypeIQ.com and w
About Epic Sciences
Epic Sciences, Inc. is developing novel diagnostics to personalize and advance the treatment and management of cancer. Epic Sciences’ mission is to enable the rapid and non-invasive detection of genetic and molecular changes in cancer throughout a patient’s journey. The company was founded on a powerful platform to identify and characterize rare cells, including circulating tumor cells. Epic Sciences No Cell Left Behind® technology helps match patients to therapies and monitor for drug resistance, so that the best treatment path can be chosen at every clinical decision point. Epic Sciences has partnered with Genomic Health to commercialize the Oncotype DX AR-V7 Nucleus Detect test, which helps with therapeutic decisions between taxane chemotherapy or androgen-directed therapeutics in metastatic castrate-resistant prostate cancer. Today, we partner with leading pharmaceutical companies and major cancer centers around the world. Epic Sciences’ goal is to increase the success rate of cancer drugs in clinical trials and improve patient outcomes by providing physicians real-time information to guide treatment choices. Epic Sciences is headquartered in San Diego. Further information is available on the Company’s website, www.epicsciences.com. Stay in touch on LinkedIn or on Twitter @EpicSciences.
Barbara Jacoby is an award winning blogger that has contributed her writings to multiple online publications that have touched readers worldwide.