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MDxHealth Reports Case Study Suggesting Benefit of Epigenetic Test, Transperineal Mapping Biopsy

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MDxHealth this week publish the case study of a 63-year-old man whose prostate cancer was diagnosed with the help of its ConfirmMDx epigenetic test and a transperineal mapping biopsy, after five standard biopsies and an MRI failed to detect the disease.

In the paper, published this week in The Journal of Oncopathology, researchers from MDxHealth and several research institutions described the case of a man whose prostate-specific antigen levels were increasing over a period of five years, from 5.2 ng/mL in 2007 to 23.33 ng/mL in 2012. Based on his PSA levels, MDxHealth's Leander Van Neste and others conducted five transrectal ultrasound-guided biopsies, which were all unable to detect any evidence of cancer. An MRI, performed last year, also didn't show any signs of the disease.

At this point, the investigators decided to perform on the patient a transperineal mapping biopsy (TPMB), a technique that employs ultrasound and a brachytherapy template grid to garner core tissue samples at 5 mm intervals. Doctors can take multiple biopsy core samples using this procedure, depending on a man's prostate size. In the case of this patient, researchers had access to 99 biopsy core samples. Of these, nine were positive for prostate cancer; one core taken from the left side of the prostate had a Gleason score of 6; two cores from the middle and left section had Gleason scores of 7; one core from the right side had a score of 9.

Finally, researchers tested the patient with MDxHealth's CofirmMDx prostate cancer test, which detects an epigenetic "field effect" or "molecular halo" around a cancer lesion that can be present despite it appearing normal under a microscope. MDxHealth has launched the test as a tool to help urologists determine whether men without prostate cancer can avoid unnecessary biopsies if they need repeat biopsies and aggressive treatment. The company claims a negative predictive value of 90 percent for the test.

In this latest study, researchers conducted a blinded analysis to gauge how well ConfirmMDx results using TPMB samples correlated with the patient's histopathology. The epigenetic assay identified all the "significant cancer lesions" that doctors found through TPMB, the authors wrote. Additionally, ConfirmMDx also identified two regions indicative of cancer in the posterior region of the prostate that were not found by TPMB or through radical prostatectomy.

"Because the epigenetic assay uses the leftover FFPE tissue, it can be applied immediately when additional investigation is required to detect occult prostate cancer," the study authors conclude in the paper. "The coordinated use of TPMB and epigenetic tests can also be used to generate information for patient prognosis. Such assays could eventually provide objective parameters for patient management using molecular marker-guided therapy."

Standard methods, such as Gleason score, to determine prostate cancer aggressiveness can vary depending on how pathologists acquire and analyze biopsies. PSA testing is also not specific enough to be used as the sole determinant of cancer risk in prostate cancer patients. MDxHealth estimates that close to 1 million men in the US have negative prostate biopsies each year, but of these men, up to 35 percent have a neoplasm.

TPMB is more expensive than the more widely used transrectal ultrasound biopsies. But research suggests TPMB is more accurate since it samples more parts of the prostate. Transrectal ultrasound biopsies sample less than 1 percent of the prostate, have a high false-positive rate, and often require as many as 45 percent of patients to get repeat biopsies.

MDxHealth is marketing ConfirmMDx as a tool that urologists can use to more definitively determine if a man is truly at low risk for prostate cancer and can avoid unnecessary biopsies. In its latest earnings report from November 2013, MDxHealth said it had tested more than 47,000 biopsies for 4,500 patients over nine months. The company is planning to report full-year and fourth quarter results on Feb. 27.

"This [recently published] case illustrates the issue associated with false-negative biopsies, the high rate of repeat biopsies for men with clinical risk factors, and how ConfirmMDx can provide a non-invasive, cost-effective solution, to improve stratification of men at risk," Christopher Thibodeau, executive VP and chief commercial officer of MDxHealth, said.

While the latest publication shows how ConfirmMDx works with TPMB samples, the test "can be performed on residual biopsy tissue from a previous 12-core [transrectal ultrasound] biopsy, and has been extensively validated to either rule out the presence of cancer, sparing cancer-free men from unnecessary invasive procedures, or as importantly, identify men who may be harboring lethal disease," he added.

MDxHealth has been steadily building up the evidence base around its prostate cancer test, its lead commercial product. In March last year, the firm reported results from a study published in the Journal of Urology showing that MDxHealth's ConfirmMDx test could accurately identify 64 percent of the prostate cancer-free men who could safely avoid a repeat biopsy with a negative predictive value of 90 percent. The study, called MATLOC, also found that ConfirmMDX correctly identified 68 percent of men who had undetected prostate cancer when they had their last histopathologically negative biopsy. When these men had a repeat biopsy they found they had cancer that required aggressive treatment.

The list price for ConfirmMDx prostate cancer is $2,400. Transrectal ultrasound biopsies cost around $3,000. The cost for performing TPMB, after factoring in general anesthesia, operating room costs, pathology work ups, can run up to an estimated $10,000.

"The TPMB is usually covered by insurance after two previous negative TRUS biopsies, but is generally viewed as too aggressive for the vast majority of men who may not have cancer," Thibodeau said.

Meanwhile, MDxHealth in recent months has announced contracts with a number of payors and estimates that its prostate cancer test is covered for 135 million lives.

The molecular diagnostics market for prostate cancer is crowded with companies like Genomic Health and Myriad Genetics having launched different types of prognostic tests for gauging prostate cancer risk. But Thibodeau doesn't feel MDxHealth's test competes with these assays, because he said those competing tests are meant to assess the aggressiveness of prostate cancers for men already diagnosed with the disease. With ConfirmMDx, the company is targeting those who have received a negative biopsy, and aren't yet diagnosed with prostate cancer, but have warning signs of disease, such as rising PSA levels.

However, at a medical conference in January, MDxHealth did report data from a study which gauged the prognostic value of ConfirmMDx. In the study, researchers evaluated 84 prostatectomy samples with varying Gleason scores for their epigenetic status of five genes -- GSTP1, APC, RASSF1, RARB and LGALS3.

In the majority of patients in the study with Gleason scores of 6 and 7 (3+4), the epigenetic test detected low gene methylation levels. But for those with Gleason score 7 (4+3) and greater than a score of 8, the test found most had intermediate to high methylation levels. "These data provide evidence of the potential prognostic value of the epigenetic profile of selected genes to identify men with a low versus high risk for aggressive prostate cancer," the company said in a statement.

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