Myriad Genetics, Inc. (NASDAQ: MYGN) has announced results from a new study that demonstrated the ability of the myRisk™ Hereditary Cancer test to detect 105 percent more mutations in cancer causing genes than conventional BRCA testing alone. The Company also presented two key studies in triple negative breast cancer (TNBC) that show the myChoice™ HRD test accurately predicted response to platinum-based therapy in patients with early-stage TNBC and that the BRACAnalysis® molecular diagnostic test significantly predicted response to platinum-based drugs in patients with metastatic TNBC. Results from these studies were presented at the 2014 San Antonio Breast Cancer Symposium (SABCS).
Myriad myRisk™ Hereditary Cancer Improved Detection of Mutations by 105 Percent
An analysis of 17,142 patients with breast cancer showed 9.5 percent of females (n=1,608) were positive for at least one deleterious or suspected deleterious gene mutation. The myRisk Hereditary Cancer test found BRCA1 and BRCA2 comprised 49 percent of the identified mutations, and 51 percent of the mutations were in other genes, representing a 105 percent increase in mutation detection over BRCA testing alone. Many of these newly identified mutations were in other breast cancer genes such as: PALB2, CHEK2, ATM and NBN. Additionally, less than 1 percent of patients had a mutation in a gene not associated with breast cancer, reducing any concerns about unanticipated results.
“Our myRisk Hereditary Cancer test is making a major scientific contribution to our understanding of hereditary cancer risk and more importantly to patient care,” said Richard Wenstrup, M.D., chief medical officer, Myriad Genetic Laboratories. “We believe panel testing provides valuable information and guidance both for the management of the patient and the patient’s family members.”
Myriad myChoice™ HRD Predicted Response in Early TNBC
In this study, researchers at Dana-Farber Cancer Institute and several other leading cancer research institutions validated the use of the myChoice HRD test in the neoadjuvant setting with TNBC. myChoice HRD is the first and only comprehensive companion diagnostic test to detect a DNA scar in tumor that is indicative of a dysfunctional DNA repair pathway. The study results demonstrated that 52 percent of patients with a deficiency defined by myChoice HRD responded to platinum-based treatment compared to only 10 percent of patients with intact HRD (P=0.001). Importantly, 28 percent of patients in the deficient HRD group had a pathologic complete response compared to none in the intact HRD group.
myChoice HRD may assist in selecting the best chemotherapy for TNBC patients before they have surgery when there is the greatest opportunity to affect a positive outcome. Patients with a deficient HRD status are likely to respond to platinum-based therapies, while patients with an intact HRD state are unlikely to respond and could be spared the added toxicity associated with these medicines.
Myriad intends to make myChoice HRD available as part of an early-access program for patients with TNBC receiving platinum-based therapy in the neoadjuvant setting in the next calendar year. The Company also has several ongoing collaborations with pharmaceutical companies to evaluate myChoice HRD as a companion diagnostic for other agents such as PARP inhibitors and in other tumor types beyond breast cancer.
BRACAnalysis® Predicted Response in Metastatic TNBC
Researchers at the UK-based Institute for Cancer Research evaluated the use of companion diagnostic assays to evaluate 310 patients with metastatic TNBC to identify which patients would respond to carboplatin or docetaxel. A key finding from this analysis is that BRACAnalysis showed that 68 percent of patients with a germline BRCA mutation had an objective response to treatment with carboplatin, compared to only 33 percent of patients who received docetaxel (P=0.03). Importantly, there was no difference between carboplatin and docetaxel in patients without a germline BRCA mutation.
Additional analysis is underway to evaluate the ability for tumor BRACAnalysis to further broaden the number of metastatic TNBC patients who could benefit from carboplatin therapy. The Company also has several ongoing research collaborations with pharmaceutical companies to evaluate BRACAnalysis as a companion diagnostic for PARP inhibitors and is currently supporting 13 Phase 3 clinical trials in three cancer types and various treatment settings.
“These results are important because metastatic TNBC is difficult to treat, and physicians need tests to better select which patients are likely to respond to a platinum drug. We are rapidly developing companion diagnostic tests to help target therapies for patients across the spectrum of TNBC,” said Wenstrup. “The studies presented at SABCS answer important clinical questions about which patients with TNBC will respond to platinum-based therapies in both early and advanced stages and which patients are unlikely to respond.”