Myriad Genetics, Inc. presented clinical data at the 2013 San Antonio Breast Cancer Symposium that showed the Myriad's HRD (homologous recombination deficiency) test was significantly associated with cisplatin response in patients with triple negative breast cancer.

In this research study, Myriad's HRD test provided optimal prediction of platinum response in patients with triple negative disease (p=0.0003). The HRD score predicted all of the patients that experienced a complete response after pre-surgical treatment with platinum with a sensitivity of 100 percent. Furthermore, these results showed that the HRD score not only predicted drug response in triple negative patients but the HRD score also was generalizable across all breast cancer subtypes.

"Often tumors with high rates of double-strand DNA repair deficiency are especially difficult to treat," said Jerry Lanchbury, Ph.D., Chief Scientific Officer of Myriad Genetics. "It is difficult to know or assess the status of all DNA repair mechanisms, so the HRD test measures the effect by assessing the amount of DNA damage. Our data demonstrate that Myriad's HRD test has the capacity to precisely target DNA damaging therapy to the patients who are most likely to respond. The HRD test has the potential to support the targeted use of PARPs and other drugs in tumors that exhibit DNA repair scars."

This is the second research study to show that Myriad's HRD test predicts drug response to platinum therapy in triple-negative breast cancer patients. In a prior study, 70 percent of patients with an HRD score ≥10 responded to the carboplatin-based treatment, compared to only 20 percent of patients with an HRD score < 10 (p=0.0001). Using the HRD test instead of BRCA status identified more than three times as many patients as likely responders.

Myriad has announced two commercial collaborations to further develop the HRD test. In March, the Company announced it is conducting HRD testing on patients enrolled in PharmaMar's Phase 2 study of PM1183. In Nov. 2013, Myriad announced a collaboration with BioMarin that will use the HRD test to identify tumor types that may be sensitive to BioMarin's investigational product candidate, BMN-673. The Company also has two other undisclosed collaborations to evaluate HRD as a companion diagnostic.

About Myriad's HRD Test

Myriad's proprietary HRD test detects when a tumor has lost the ability to repair double-stranded DNA breaks resulting in increased susceptibility to DNA-damaging drugs. Myriad's HRD test includes three DNA-based measures of homologous recombination deficiency including: whole genome tumor loss of heterozygosity profiles (HRD-LOH), telomeric allelic imbalance (HRD-TAI) and large-scale state transitions (HRD-LST). All three scores are highly correlated with defects in BRCA1/2 and are associated with sensitivity to platinum agents. High HRD scores are prevalent in all breast cancer subtypes and most other major cancers. It is estimated that 490,000 people in the United States who are diagnosed with cancers annually are candidates for HRD testing with the view to recommend treatment with DNA-damaging agents such as platinum and PARP inhibitors.