UPDATE: April 4, 2019: Myriad Genetics said it expanded its collaboration with AstraZeneca and Merck. Its BRACAnalysis CDx diagnostic will be used to find germline BRCA mutations in men with certain prostate cancers in a Phase 3 study. If the results are positive, Myriad said it will file a supplementary premarket approval application for the product as a companion diagnostic to Lynparza for such patients.

Dive Brief:

• Myriad Genetics' BRACAnalysis CDx test has supported another successful Phase 3 clinical trial of AstraZeneca and Merck & Co.'s PARP inhibitor Lynparza.

• Researchers used the companion diagnostic to identify metastatic pancreatic cancer patients with deleterious germline BRCA mutations.

• Myriad plans to file a supplementary Premarket Approval (sPMA) with FDA to expand use of its test into a new indication.

Dive Insight:

Since entering into a collaboration with AstraZeneca in 2007, Myriad has supported each step in the development of Lynparza, the first FDA-approved PARP inhibitor. As BRCA mutation status appears to be critical to the efficacy of PARP inhibitors, AstraZeneca needs to select its clinical trial participants carefully to maximize its studies' chances of success. The Myriad test helps facilitate patient selection.  

In the latest trial, AstraZeneca and Merck wanted to identify patients with germline BRCA-mutated metastatic adenocarcinoma of the pancreas who had stable disease or better following treatment with platinum-based chemotherapy. BRCA status was either determined prior to enrollment in the trial or using Myriad's companion diagnostic once a patient was put forward for the study.

The 154-subject POLO trial showed that, in patients with the genetic marker identified by Myriad, Lynparza is better than placebo at controlling pancreatic cancer in a first-line, maintenance therapy setting. If the data lead to the approval of Lynparza in the indication, the findings could expand use of both the PARP inhibitor and Myriad's companion diagnostic.  

"The results of the POLO trial strongly support use of the BRACAnalysis CDx test to help inform treatment decisions in the metastatic pancreatic cancer setting and will expand the patient population who can benefit from BRCA testing," Myriad CMO Johnathan Lancaster said in a statement.  

A successful sPMA in the new indication would continue the steady expansion of use of Myriad's companion diagnostic since it was first cleared late in 2014. That original approval covered use of the test to identify ovarian cancer patients eligible for fourth-line treatment.

Since then, Myriad has received approvals to use the BRCA test in identification of breast cancer patients and ovarian cancer patients eligible for second or first-line treatment with Lynparza. In parallel, Myriad has supported the emergence of rivals to Lynparza, including Pfizer's Talzenna and Tesaro's Zejula.

Myriad reports its companion diagnostic sales as part of its hereditary cancer business, making it hard to tell how well the test is performing commercially. But in the most recent quarter, the wider hereditary cancer business returned to growth and Myriad CEO Mark Capone said the companion diagnostic unit "does continue to ramp up."