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MDx/CDx Focus: BioTheranostics Compares CancerType ID to IHC; Myriad's HRD Test


BioTheranostics Study Finds 92-Gene Classifier More Accurate than IHC in Diagnosing Metastatic Tumors

BioTheranostics has published a study that supports the clinical utility of its 92-gene molecular classifier for diagnosing metastatic cancer.

The study, published in the current issue of the Journal of Molecular Diagnostics compared the company’s CancerType ID test to immunohistochemistry in identifying the primary site in difficult-to-diagnose metastatic tumors.

Researchers from the company found that the 92-gene RT-PCR assay had "superior accuracy" compared to IHC analysis and said the results "strongly support the diagnostic utility of molecular classification in difficult-to-diagnose metastatic cancer."

The company said that the comparative effectiveness study is the first to directly compare the diagnostic accuracy of the two tumor classification techniques.

In the blinded study, conducted in collaboration with the City of Hope National Medical Center, 122 high-grade, primarily metastatic tumors considered diagnostically challenging were evaluated with either IHC or CancerType ID. Results were scored using reference diagnoses established by detailed clinical correlation.

In these samples, CancerType ID demonstrated overall accuracy of 79 percent for tumor classification versus 69 percent for IHC analysis. The company said in a statement that performance differences favoring CancerType ID "were more than 20 percent when greater than nine IHC stains were used, likely due to the poorly differentiated nature of the cancers."

The company said that the results highlight the test's "immediate clinical utility when an initial IHC panel does not lead to a definitive diagnosis, and when tumor specimen is limited and expanded IHC testing is likely to exhaust tissue that may be needed for predictive biomarker testing."

Myriad to Conduct HRD Testing for PharmaMar Clinical Study

Myriad Genetics said this week that it will conduct homologous recombination deficiency testing on patients enrolled in a phase II clinical study for an anti-tumor drug candidate under development by marine-derived drug developer PharmaMar.

Myriad will conduct HRD testing for patients in a clinical study for PharmaMar's PM1183, which induces double-stranded DNA breaks to cause cell death.

Myriad said its test can detect when tumors can no longer repair DNA damage, making them more susceptible to DNA-damaging drugs, such as PM1183. The test "directly measures the end result of the loss of the DNA repair function regardless of the genomic causation," the company said in a statement, adding that the test has demonstrated an ability to predict drug response in both ovarian cancer patients and triple-negative breast cancer patients.

The partnership with PharmaMar is the first that Myriad has publicly disclosed for the HRD test, which it has been developing as a potential companion diagnostic to determine whether patients will benefit from DNA-damaging agents such as platinum therapies and PARP inhibitors.

Myriad estimated that 490,000 Americans are diagnosed with cancers each year that are eligible for treatment with DNA-damaging classes of drugs, representing a potential market of $1 billion to $2 billion market in the US alone.