NEW YORK – With the launch of its at-home sample collection kit, University of Michigan spinout Lynx Dx aims to expand the reach of its urine-based test to help determine which patients likely have clinically significant prostate cancer and should undergo biopsies.
Lynx Dx Chief Medical Officer Spencer Heaton said that the launch last week of the Lynx Dx MyProstateScore 2.0 (MPS2) test kit, allowing the test to be used in a patient's home, was years in the making. Though it has been available as a laboratory-developed test since February 2023, the assay previously had to be performed in combination with a digital rectal examination. Discomfort with that procedure among both patients and providers had limited uptake of the test, he said.
Patients still need to undergo a prostate-specific antigen (PSA) blood test prior to the use of MPS2. However, Heaton said that clinicians can now order the test kit to a patient's home based on the results of the PSA test rather require another visit to perform the MPS2 assay.
Reducing the number of office visits can improve testing access for patients who live in rural areas where there are no practicing urologists as well as among patients who have long wait times to see specialists, he said. He also noted that samples shipped using the collection kit are shelf stable, which further adds to the convenience of the kit. The sample is shipped to Lynx Dx's lab in Michigan for PCR-based testing.
PSA tests can help to identify prostate cancers, but they lack specificity. PSA levels fluctuate, and benign conditions such as inflammation or enlargement of the prostate can also cause elevated PSA levels.
About 25 percent of patients who undergo biopsy due to an elevated PSA level will receive a diagnosis of prostate cancer, according to the National Cancer Institute.
MPS2 is used to detect clinically significant high-grade cancers and differentiate them from slow-growing or indolent cancers that are unlikely to cause symptoms or become life-threatening. It is used in patients with elevated PSA levels to determine a patient's risk of cancer with a Gleason score of 7 or higher or a Grade Group of 2 or higher.
The test has 18 genetic targets, comprised of the SCHLAP1, APOC1, NKAIN1, and B3GNT6 genes that are associated with high-grade prostate cancer, 13 other markers of prostate cancer, and one reference gene.
Heaton noted that the results can be reported to urologists by themselves or analyzed in combination with other risk factors such as patient age and race.
The assay is one in a slate of tests to help determine whether patients with elevated PSA scores are at risk of prostate cancer, including Bio-Teche's urine-based ExoDx Prostate Test, which is also available with an at-home sample collection kit. Bio-Techne's Exosome Diagnostics business launched its collection kit in April 2020.
Arul Chinnaiyan, founder of Lynx Dx and professor of pathology and urology at the University of Michigan, said that recently published study results show that MPS2's performance is equivalent when it is performed with urine samples that are collected following digital rectal examination or urine samples that are collected and analyzed without the exam.
Heaton and Chinnaiyan are among the authors of an article that was published last month in the Journal of Urology on the performance of MPS2 when the biomarker-based results were used alone, in combination with clinical factors such as a patient's age and race, or in combination with clinical factors as well as imaging-based prostate volume measurement. The researchers performed the test ahead of prostate biopsy on patients who had an elevated PSA or abnormal digital rectal examination results but no prior prostate cancer diagnosis. Among 266 patients in the study, 103 were confirmed to have Grade Group 2 or higher cancer.
The authors wrote that the test identified Grade Group 2 or higher cancers with an area under the curve of 71 percent with biomarkers alone, and it had a negative predictive value of 93 percent. According to them, the results could have been used to avoid 36 percent of unnecessary biopsies.
When other clinical factors were analyzed along with biomarker-based results, the test performance improved by a statistically insignificant amount, to an AUC of 74 percent, the authors said. The performance improved to an AUC of 77 percent with the combined use of biomarkers, clinical factors, and prostate volume measurement, while the NPV increased to 95 percent, and the test could have been used to avoid 42 percent of unnecessary biopsies.
The authors wrote that MPS2's biomarker-based results alone were in line with previously reported results from the ExoDx Prostate IntelliScore test. Bio-Teche did not respond to a request for comment.
Andrew Vickers, attending research methodologist at Memorial Sloan Kettering Cancer Center, said that he has advocated for using methods such as biomarker-based tests and MRI to reduce overdiagnosis and overtreatment by determining whether patients with high PSA scores should undergo biopsies. He helped to develop Opko's US Food and Drug Administration-approved blood-based 4KScore prostate cancer test that uses four prostate-specific kallikrein biomarkers along with patient clinical information to determine the presence of aggressive cancers and aid decisions whether to perform biopsies.
Vickers said that many blood- and urine-based tests are available to help determine which patients with high PSA scores should have biopsies, although he noted that urine-based tests have generally been unpopular because they have required the use of digital rectal examination procedures to force biomarkers from the prostate into urine.
Chinnaiyan said that Lynx Dx has increased the sample size used in MPS2 when it is used with home-collected samples to compensate for the absence of digital rectal examination. MPS2 is performed on 2-3 milliliters of urine when it is used with a home-collected sample compared to about 100 microliters when the test follows digital rectal examination, he said.
As for the convenience of MPS2, Vickers said that a single blood sample can be used for both PSA testing and blood-based follow-up tests. However, he noted that urologists seem to seldom perform such testing from the same sample.
Heaton said that Lynx Dx's sales team is going office to office to tell urologists about the test, and the firm has received boosts from well-received publications. The firm has also been frequenting conferences that are attended by urologists and working in concert with patient advocacy organizations to increase awareness about the test, he noted.
MPS2 is covered by Medicare at $760 per test, and the company has in recent quarters secured expanded coverage by regional and national private insurers. The company is focused for now on expansion in the US although he noted that the firm has received some inquiries from healthcare providers outside the US.
Chinnaiyan said that further studies of MPS2 are underway, including a clinical study on the use of the test to monitor patients with low-grade prostate cancers and predict progression to high-grade cancer. The company is also studying the utility of the test when it is performed by a primary care physician rather than a urologist.