TESARO and Myriad Expand Collaboration with New CDx Pair

The new collaboration will utilize the Myriad Genetics (Salt Lake City, UT, USA, and Zurich, Switzerland) companion diagnostic (CDx) “myChoice HRD” test to identify tumors with a homologous recombination deficiency (HRD). Under the terms of the agreement, TESARO, Inc. (Waltham, MA, USA) will use the test to enrich the target population for potential responders to niraparib. Myriad will provide testing services and pursue necessary regulatory approvals in support of TESARO's development of niraparib (a potent poly-(ADP-ribose)-polymerase inhibitor).

"We are excited to be expanding our collaboration with TESARO," said Jerry Lanchbury, PhD, chief scientific officer at Myriad, "myChoice HRD utilizes three proprietary measures to assess the genomic scar associated with the loss of DNA repair and has been shown in multiple clinical studies to be the most comprehensive predictor of tumor response to DNA-damaging agents such as niraparib."

Many cancer patients may be candidates for treatment with DNA-damaging agents. Myriad's proprietary myChoice HRD detects DNA scars indicative of a tumor that has lost the ability to repair double-stranded DNA breaks—resulting in increased susceptibility to DNA-damaging drugs. High HRD scores reflective of DNA-repair deficiencies are prevalent in all known breast cancer subtypes and most other major cancers. In previously published data, Myriad showed that the myChoice HRD test predicted drug-response to platinum therapy in triple-negative breast cancer patients.

"Myriad's myChoice HRD diagnostic test identifies inherent biology of the tumor and differentiates tumors with homologous repair deficiencies from those without such deficiencies," said Mary Lynne Hedley, PhD, president and COO of TESARO, "Niraparib sensitivity in patient-derived xenograft models is associated with HRD status as defined by the myChoice HRD test." New data, demonstrating that the myChoice HRD test score is predictive of niraparib sensitivity in patient-derived xenograft models of ovarian cancer, have now presented by Mayo Clinic Prof. Paul Haluska, Jr, MD, PhD, at the 26th EORTC-NCI-AACR Symposium on Molecular Targets and Cancer Therapeutics (Barcelona, Spain).

In the xenograft study, patient-derived xenografts were created from more than 100 high-grade serious ovarian cancer tumor samples. HRD testing was performed on each sample using myChoice HRD to define HRD status, detect BRCA-1 and -2 mutations, and identify hypermethylation of BRCA genes. Approximately half of these models were HRD positive and are being evaluated for sensitivity to niraparib in vivo. Preliminary data from treated models indicate all models that responded to niraparib treatment had an HRD score above the predetermined cutoff value and included both BRCA mutant and BRCA wild type tumors. Evaluation of niraparib sensitivity across the full set of selected models is ongoing. These initial results indicate that identifying patients with homologous recombination deficiencies using myChoice HRD may help to identify patients who are most likely to respond to treatment with niraparib.

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