Another win for precision medicine: FDA approves companion diagnostic panel

After decades of research and theoretical debates, it seems precision oncology is finally falling into place, capped off with Thursday’s approval of a companion diagnostic for multiple cancer therapies.

After decades of research and theoretical debates, it seems precision oncology is finally falling into place.

At the end of May, FDA triggered a seismic shift in the field with its decision to approve a therapy based on a genetic signature, not a tissue of origin. The ruling solidified the field’s move towards the use of biomarkers to precisely target each person’s cancer, rather than blindly administering toxic agents.

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A Deep-dive Into Specialty Pharma

A specialty drug is a class of prescription medications used to treat complex, chronic or rare medical conditions. Although this classification was originally intended to define the treatment of rare, also termed “orphan” diseases, affecting fewer than 200,000 people in the US, more recently, specialty drugs have emerged as the cornerstone of treatment for chronic and complex diseases such as cancer, autoimmune conditions, diabetes, hepatitis C, and HIV/AIDS.

On Thursday, another big milestone was reached with FDA’s premarket approval (PMA) of the first companion diagnostic for multiple drugs, the Oncomine Dx Target Test. A PMA is the most stringent type of device marketing application required by FDA.

Developed by Thermo Fisher Scientific, the assay uses next-generation sequencing (NGS) to simultaneously screen for 23 cancer genes. Three of those genes are tied to three different FDA-approved therapies for non-small cell lung cancer (NSCLC).

And that’s just the beginning.

Via phone, Thermo Fisher’s President of Clinical NGS Joydeep Goswami noted that the regulatory work has already been done for further indications.

“While we presented evidence of analytical validation of all the different genes, given the initial companion drugs were all non-small cell lung cancer-related, the FDA chose to initially limit this approval to that patient group,” he said.

After all, it’s all new territory for the agency as well.

“It’s the first-ever multi-biomarker NGS, IVD [in vitro diagnostic], companion diagnostic that was ever approved. And also, I think for the FDA, for multiple drugs being approved for a companion diagnostic at the same time.”

The company intends to work with the FDA to get more genes added to the panel, more companion therapies matched, and more indications for use in different tissues. At least one other company, Foundation Medicine, is working on a multi-biomarker, multi-drug companion test.

Lung cancer is a good starting point for a number of reasons: The genes are actionable, the samples are hard to collect, and time is of the essence.

With this NGS test, the sample requirement is very small and it delivers results in a matter of days, Goswami said. That compares to the single biomarker, sequential testing techniques using PCR or IHC, which take weeks and use a large amount of sample with each test. Oncologists don’t want to go back for more.

“The cost of a lung biopsy, at the best of times, is somewhere in the $5,000-$20,000 range,” Goswami explained. “But if there are complications, which is often the case with compromised patients, it can go up to $40,000 or more.”

Perhaps more importantly, the procedure is an immense burden on already sick patients, he stated.

The companion therapies are made by Pfizer, AstraZeneca, and Novartis. The latter also received approval for its combination therapy on Thursday, in concert with the approval of the Oncomine Dx Target Test. FDA noted both in its announcement.

For Goswami, the greatest advantage of a companion diagnostic tied to multiple drugs is its ability to democratize access to precision medicine.

When FDA announced its approval of Keytruda for a biomarker, it incited a lot of debate about the number of patients that were getting their tumors sequenced. As it stands, an NSCLC patient at a top academic institution, such as Mayo Clinic, will likely get the tests required to confirm their eligibility for all the approved therapies or clinical trials. Yet these are laboratory-developed tests (LDTs), which are tied to a single clinical location.

The Oncomine Dx Target Test will be available nationwide; LabCorp’s Diagnostics and Covance Businesses, NeoGenomics Laboratories, and Cancer Genetics have all signed up as early adopters.

“I don’t see why any patient should not have access to this technology,” Goswami said.

Thermo will start discussions with payers and the Centers for Medicare and Medicaid Services now that the approval is finalized.

If the trend continues, biomarkers will become an increasingly important part of cancer treatment. But it’s not always a one-to-one equation. These mutations are often actionable in unexpected ways.

Take, for example, Merck’s flagship immunotherapy Keytruda. In an early June interview, Merck’s SVP, Head of Global Clinical Development, and CMO Roy Baynes said the company is currently taking a four-pronged approach to its diagnostics. The first is testing for PDL-1, the biomarker that the drug targets and binds. The next is testing for inflammatory signals more broadly. The third is looking for tumors that are MSI-high, the mutation tied to the landmark FDA approval. And finally, there is evidence to suggest that a broadly high tumor mutational burden correlates with a response to checkpoint inhibitors such as Keytruda.

If physicians only tested for PDL-1, they wouldn’t be maximizing the drug’s potential.

It’s a reminder that we need to cast the net as wide as possible for potential mutations, in all patients.

Photo: Nataniil, Getty Images