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Perthera Partners With Counsyl to Offer Germline Testing of Cancer Patients


NEW YORK (GenomeWeb) – Personalized medicine firm Perthera has begun offering germline genomic testing through a partnership with genetic screening firm Counsyl.

The germline testing will determine if patients are carriers of hereditary mutations linked to cancer, allowing them to notify family members, said Emmanuel Petricoin, a Perthera co-founder and co-director of the Center for Applied Proteomics and Molecular Medicine at George Mason University. Additionally, he said, the germline data could help guide patient therapy, which is the primary purpose of the company's Precision Cancer Analysis (PCA) service.

In the case of cancer, germline genomic panel testing like Counsyl's has primarily been used to assess patients' predispositions for various cancers, perhaps most famously in the instance of the BRCA1 and BRCA2 hereditary breast and ovarian testing offered by Myriad Genetics and other firms including Counsyl.

It has been less widely used for assessing and managing patients who currently have cancer, as clinicians typically opt, when possible, to do molecular testing on the tumor tissue itself, or, when this is not possible, use various liquid biopsy approaches to detect DNA and protein shed by tumors.

Petricoin said, though, that research increasingly indicates that germline testing could provide additional information that could help not just predict a patient's risk of developing cancer but their likely response to different cancer therapies.

"What has happened is a number of the genes have moved from just being prognostic as far as risk to being predictive and actually predicting response to specific inhibitors," he said. "Depending on the number of copies, mono- or bi-allelic changes in, say, BRCA1/2, it can have dramatic effects on things like PARP inhibitor response across a population."

This week provided an example of the utility of germline testing for guiding cancer therapy as the US Food and Drug Administration said it has approved Myriad's BRACAnalysis CDs as a complementary diagnostic to help identity cancer patients with germline mutations who are most likely to benefit from treatment with Tesaro's PARP inhibitor Zejula (niraparib).

"BRCAness is a feature of multiple different tumors, and the likelihood that someone will have [it] as a feature of their tumor is certainly markedly increased if they have a germline mutation in the double-strand break repair pathway," said Harry Ostrer, a clinical geneticist and professor of pathology at Albert Einstein College of Medicine, speaking to the role of germline testing in guiding cancer therapy.

In principle, said Ostrer, who is not affiliated with Perthera, this role could extend beyond the question of BRCAness to other cancer-linked germline mutations. However, he said that relationships between other such mutations and specific drugs were less well established.

"I think there has been such a race towards looking at tumors themselves —[an attitude of] why don't we just look at the tumor and target the pathway of the tumor?" he said. "And with regard to what we know about hereditary cancers, we have a relatively discrete number of pathways that are commonly tested for."

Nonetheless, the idea that looking at germline mutations could guide cancer therapy is "a totally reasonable hypothesis," Ostrer said, noting in particular mutations linked to DNA repair. "So many drugs target damaging DNA, whether they are anti-metabolites or alkylating agents, that it is very reasonable to think about whether germline mutations in pathways that affect DNA repair are going to be enhancing the response to those drugs. But it hasn't been looked at systematically."

Perthera will offer patients Counsyl's Inherited Cancer Screen, which looks at up to 36 genes linked to hereditary cancers in men and women. Though the focus of the Perthera relationship is cancer, South San Francisco, California-based Counsyl has stepped back from the oncology space in recent months, announcing in January that it is laying off its dedicated oncology sales team, which made up around 5 percent of its employees.

The company said that it planned to focus its efforts on women's health, though it added that would continue development of its cancer test.

Petricoin said that the notion of adding germline testing began "bubbling up" as Perthera began to expand its work into cancer types like breast and ovarian where germline BRCA1/2 testing is already part of standard workups. He noted, though, that the company has also seen relatively frequent BRAC1/2 alterations in pancreatic cancer, which was until recently its main area of focus.

This, he said, suggests a role for germline testing in these patients to see if they might be eligible for PARP inhibitor trials. It could also help patients identify hereditary mutations that they would want to alert family members to.

That latter consideration was a significant driver of Perthera's decision to partner with Counsyl to offer the germline testing, Petricoin said, noting the latter company's genetic counseling offerings.

"Counsyl does the germline testing and the genetic counseling component," he said.  "So we can say, 'Hey look, we found this in your tumor.' We report it to you, and here's a genetic counselor that can talk to you about it, if you want. Or, if you'd rather not have [germline testing] done, we won't do it and will just do the somatic analysis of your tumor. It's up to you."

Perthera was launched in 2013 by Petricoin and venture capitalist Dendy Young with the aim of providing cancer patients, particularly in the community setting, the sort of molecular profiling and expert interpretation typically available at major cancer centers.

The company does not perform the assays itself but helps physicians access genomic, proteomic, and phosphoproteomic profiling services from outside providers, serving as an intermediary handling the many steps involved in obtaining and sending out patient tumor samples to molecular profiling firms and returning assay results.

In addition to the newly announced relationship with Counsyl, Perthera sources tumor genomic analyses from Foundation Medicine, proteomic data from Caris Life Sciences, and phosphoproteomic data from Theranostics Health, of which Petricoin is also a co-founder.