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Myriad to Perform BRCA Companion Dx Testing for BioMarin's PARP Inhibitor BMN 673


Originally published April 11.

Last week, just days after Myriad Genetics defended its BRCA patents before the federal circuit court of appeals in Association for Molecular Pathology et al. vs. the United States Patent and Trademark Office et al., the company announced a deal to develop a companion BRCA 1/2 test for BioMarin's PARP inhibitor BMN 673.

The agreement marks Myriad's third agreement to use its BRACAnalysis test as a companion diagnostic for a PARP inhibitor.

BioMarin is developing BMN 673 for genetically defined cancers. Myriad will apply its BRACAnalysis test in clinical trials for BioMarin to determine if patients have BRCA1 and BRCA 2 mutations and therefore should receive the PARP inhibitor.

The PARP1 enzyme and the BRCA gene work in concert to repair DNA damage, enabling the tumor to survive. However, in patients with mutations in the BRCA gene, when PARP inhibitors destroy the PARP1 enzyme, the tumor is unable to repair DNA damage and dies.

Under the agreement announced last week, Myriad will perform large rearrangement testing with its Comprehensive BRACAnalysis test to gauge the presence of germline mutations in patients prior to enrolling in the study.

According to, in January BioMarin launched a Phase I/II study for BMN 673, a single-arm, open-label trial to assess the safety, pharmacokinetics, pharmacodynamics, and preliminary efficacy of the drug in patients with advanced or recurrent solid tumors who have DNA-repair pathway deficiencies. The second part of the study will attempt to define the maximum tolerated dose and include a dose expansion phase.

Myriad entered the companion diagnostics field last year by inking separate deals with Abbott and AstraZeneca to conduct BRCA testing in clinical trials investigating PARP inhibitors (PGx Reporter 06/30/10). AstraZeneca is using the BRACAnalysis test in the development of olaparib in breast and ovarian cancer and Abbott is using the test to stratify breast cancer patients in clinical trials for veliparib.

When Sanofi-Aventis announced in January that its PARP inhibitor for triple-negative breast cancer had failed in Phase III clinical trials, it negatively affected Myriad's stock, even though Sanofi did not use BRCA testing to stratify patients in clinical trials for the drug (PGx Reporter 02/02/2011).

The latest companion diagnostics collaboration with BioMarin was seen as a positive upturn for Myriad by industry analysts.

"While we do not expect the agreement [with BioMarin] to significantly impact revenues for Myriad, we believe the uptake by biopharmaceutical companies of BRACAnalysis, as well as Myriad’s other genetic tests such as Prezeon for PTEN status, is an important, long-term growth driver for Myriad," Peter Lawson, an analyst with Mizuho Securities, wrote in a research note.

"This uptake would expand the tests from traditional diagnostic applications and into companion diagnostics and personalized medicine, actively helping to select appropriate therapies for individual patients," Lawson said.