In a study sponsored by Epic Sciences, San Diego, in partnership with Memorial Sloan Kettering Cancer Center, researchers have demonstrated that a liquid biopsy blood test may be used before treatment is initiated in clinical trials to find patients who are likely to benefit from therapies targeting prostate-specific membrane antigen.1

Epic Sciences Figure 1 Blood sample collection

To detect the presence of PSMA-positive CTCs in patients with metastatic prostate cancer, blood samples are shipped to Epic Science’s lab in San Diego within 48 hours of the patient’s blood draw.

Developed by Epic Sciences, the blood test looks on the surface of circulating tumor cells (CTCs) for a specific protein, called prostate-specific membrane antigen (PSMA), which is highly expressed in prostate cancer. In the study, the presence of PSMA-positive CTCs in patients with metastatic prostate cancer was related to the patient’s therapeutic response and clinical outcomes after treatment with an antibody-drug conjugate (ADC) targeting PSMA-positive prostate cancer cells.

The study found that expression of the PSMA protein on CTCs was heterogeneous; meaning that every patient who had PSMA-positive CTCs also had populations of PSMA-negative CTCs. Epic previously reported that PSMA heterogeneity, as detected by Epic’s CTC analysis, provided clinical insight to varying therapy responses and outcomes among metastatic prostate cancer patients. For these patients, multiple PSMA-targeted therapeutics are being developed, and ADCs represent an emerging drug class that may be more effective with fewer side effects. ADCs are designed to deliver cytotoxic payloads directly to tumor cells by targeting proteins differentially expressed on cancer cells.

Epic’s digital pathology software analyzes the image files for a multitude of immunofluorescent and morphological features on an estimated three millions cells per slide.

Epic’s digital pathology software analyzes the image files for a multitude of immunofluorescent and morphological features on an estimated three million cells per slide.

“While clinical responses to PSMA-targeted therapies are being observed, the success of these targeted ADC drugs in the clinic will likely depend on biomarkers to better understand target antigen expression, target-drug engagement, and therapeutic response,” says Ryan Dittamore, chief of medical innovation at Epic Sciences and coauthor of the study. “The data suggest that identifying PSMA-positive circulating tumor cells and analyzing CTC heterogeneity can greatly aid drug development through proper patient selection.”

The cost of developing a new, targeted cancer drug is estimated to exceed $2 billion, in part because of low success rates and expensive, lengthy clinical development cycles.The increase in development costs translates to increased drug prices. Newly approved targeted cancer drugs are costing more than $10,000 per month, and the costs are growing at approximately 9% per year.3


Ryan Dittamore, Epic Sciences.

“We desperately need ways to improve and accelerate the clinical development of cancer drugs,” says Dittamore. “The potential for a blood test to help select patients for therapy, and then also aid as an early response measure, is an important advancement to drug development and has potential to improve outcomes and reduce cost.”

Epic currently partners with 65 biopharma partners and 40 academic institutes, and is involved in more than 250 clinical studies. Epic has developed more than 40 unique assays for the characterization of drug targets using the company’s unique blood-testing platform.


  1. Autio KA, Dreicer R, Anderson J, et al. Safety and efficacy of BIND-014, a docetaxel nanoparticle targeting prostate-specific membrane antigen for patients with metastatic castration-resistant prostate cancer: a phase 2 clinical trial. JAMA Oncol. 2018;4(10):1344–1351; doi: 10.1001/jamaoncol.2018.2168.
  1. DiMasi JA, Grabowski HG, Hansen RW, et al. Innovation in the pharmaceutical industry: new estimates of R&D costs. J Health Econ. 2016;47:20–33; doi: 10.1016/jhealeco.2016.01.012.
  1. Savage P, Mahmoud S, Patel Y, Kantarjian H. Cancer drugs: an international comparison of postlicensing price inflation. J Oncol Pract. 2017;13(6):e538–e542; doi: 10.1200/jop.2016.014431.

Featured image: A circulating tumor cell found using Oncotype DX AR-V7 nucleus detect by Epic Sciences.