Genetic test for prostate radiation risk assessment launches on US market

MiraDx has announced US commercial availability of PROSTOX Standard, a clinically validated germline genetic assay designed to estimate the risk of late genitourinary (GU) toxicity following conventionally fractionated or moderately hypofractionated radiation therapy (CFRT or MHFRT) for localized prostate cancer.¹

The launch of PROSTOX Standard expands the PROSTOX portfolio of risk assessment tools for patients who are undergoing external beam radiation therapy (EBRT). The company’s existing assay, PROSTOX Ultra, assesses the risk of long-term urinary adverse effects in patients being considered for stereotactic body radiation therapy (SBRT).

“PROSTOX tests bring precision medicine to radiation oncology by shifting the focus from the tumor alone to determining the most effective treatment approach for each patient based upon their unique biology and resulting treatment risks,” said Melissa C. Stoppler, MD, Executive Vice President of Medical Affairs at MiraDx, in the news release from the company.¹ “Having information about which type of radiation each patient will tolerate best allows clinicians to better tailor radiation treatments to patients, helping them avoid future long-term [adverse] effects.”

According to the company, the PROSTOX platform evaluates inherited germline microRNA–associated genetic variants (mirSNPs) believed to influence individual response to radiation exposure. These mirSNPs are implicated in biological pathways involved in DNA damage repair, inflammation, and cellular stress responses, which may contribute to variability in radiation tolerance and risk for late toxicity.²

The newly introduced PROSTOX Standard test is intended for use in patients undergoing CFRT (37–45 fractions over 7–9 weeks) or MHFRT (20–28 fractions over 4–5 weeks). Test results are derived from a buccal swab and are reported within approximately 5 to 7 days.

Clinical data provided by the company show that PROSTOX Ultra has a negative predictive value (NPV) of 96%, positive predictive value (PPV) of 77%, sensitivity of 70%, and specificity of 95%. For PROSTOX Standard, reported performance metrics include an NPV of 93%, PPV of 75%, sensitivity of 70%, and specificity of 95%.²

“Previously, we would make decisions based on existing practice patterns at an institution, the comfort [physicians] have with their existing treatment algorithms, and patient preferences for logistics of [treatment schedules]. Now that we have the option of doing the PROSTOX test, we can add the genetic risk profile for late toxicities as another factor in deciding which regimen of radiation treatment they should receive to try to balance the risks and benefits in a new way,” added Austin Kirschner, MD, PhD, of Vanderbilt University Medical Center, Nashville, Tennessee, in an interview with Urology Times®. “This really is changing practice patterns, because we can use this to guide recommendations for which treatment schedule a patient should receive.”

Although both PROSTOX tests evaluate the risk of long-term urinary adverse effects following EBRT, MiraDx cautioned that each test evaluates genetic risk for a different radiation regimen, so results cannot be generalized. In other, words, a high-risk result with PROSTOX Standard does not imply a high-risk result with PROSTOX Ultra, and vice versa.

The company also noted, “In rare cases (less than 2% of patients), PROSTOX tests will identify that a patient has a high risk for late GU [adverse] effects with both SBRT and CFRT/MHFRT. For these patients, other interventions may be available.”

Result interpretation is performed at MiraDx’s CLIA-certified and CAP-accredited molecular diagnostics laboratory in Los Angeles, California. MiraDx also offers a financial assistance program intended to support patient access to PROSTOX testing.

REFERENCES

1. MiraDx launches new genetic test expanding radiation therapy risk assessment for prostate cancer patients. News release. MiraDx. February 24, 2026. Accessed February 24, 2026. https://miradx.com/new-genetic-test-radiation-risk-assessment-prostate-cancer/

2. PROSTOX Evidence. MiraDx. Accessed February 24, 2026. https://miradx.com/prostox/evidence/#prostox