NEW YORK (GenomeWeb) – Pathway Genomics on Thursday launched the first liquid biopsy test, called CancerIntercept Detect, aimed at the early discovery of malignancies in asymptomatic people with an elevated risk of developing cancer.
Though leaders in the liquid biopsy research field have said they are still waiting for the first demonstration of a technology's ability to detect cancer in undiagnosed patients with the appropriate clinical sensitivity and without a high rate of false positives, Pathway believes its platform has the ability to meet the appropriate threshold.
However, the company has released no scientific data on its test, which interested individuals can now receive either through their own physician or by ordering directly from Pathway's website, where their medical and family history is reviewed by a company-associated physician to determine eligibility.
Ardy Arianpour, Pathway's chief commercial officer, told GenomeWeb today that the new test is based on targeted next-gen sequencing to identify the presence of 96 somatic mutations occurring in nine cancer-associated genes: BRAF, CTNNB1, EGFR, FOXL2, GNAS, KRAS, NRAS, PIK3CA, and TP53.
A sister version of the test, CancerIntercept Monitor, which is intended not for diagnosing incipient cancer, but rather for monitoring existing disease, also measures the same markers and genes.
Using these targets, Pathway claims the test is appropriate for the early detection of a variety of cancers including colorectal, breast, ovarian, and lung cancers, and melanoma, among others.
As a single test, CI Detect costs $699. But customers wishing to use the test on an ongoing basis pay $499 per test for an annual subscription, $399 with a semi-annual plan, and $299 per test if they repeat tests quarterly.
Though not precisely a direct-to-consumer model, the ability to order the test by submitting a request directly to the company clearly expands the possibilities for access beyond traditional paradigms of laboratory testing.
According to Arianpour, testing cannot be done in the total absence of physician involvement. Patients can, however, submit themselves as candidates for testing without consulting their own primary care doctor first.
"The patient needs to provide a physician contact who will be contacted in the event of a positive result," he explained. Any positive results are then released to the chosen physician. Negative results get released directly to the patient and to the primary care physician.
Arianpour was not able to define an exact cutoff point that physicians assessing cases submitted directly to the company would use to determine whether an individual should or should not be tested.
However, he said, a 45-year-old female with a germline BRCA1/2 mutation or a 50-year-old male with a lifetime history of smoking, for example, would fall into the eligible category. "A 20-year-old healthy individual without any suggestive family history or other risk factors would not be eligible, even though the individual may be worried about developing cancer," Arianpour told GenomeWeb via email.
Overall, the types of indicators of elevated risk the company considers include family history and the presence of cancer risk mutations, well-known environmental factors like smoking or exposure to radiation, and even more exceptional risk factors, for example, potential carcinogen exposure among first responders to the terrorist attacks of 9/11, Arianpour said.
Without available data on the clinical performance of Pathway's early detection test, questions remain about what distinguishes it from other offerings on the market.
Luis Diaz, a researcher at Johns Hopkins who is also associated with another company developing liquid biopsy tests, Personal Genome Diagnostics, told GenomeWeb today that being able to detect cancer early with a simple blood test is "one of the holy grails of medicine."
"However," he said, "everyone understands that getting there is not going to be trivial."
On its website, Pathway reports that depending on the amount of cell-free DNA isolated, its analysis enables the reporting of as few as two mutant DNA copies per 5-ml blood plasma.
This does not appear to be much of a departure from the metrics reported by other liquid biopsy companies, many of whom have expressed that their own technologies may not be quite ready for early cancer detection.
According to Diaz, Pathway's test doesn't appear, based on available information, to be significantly different from the assays being developed by companies like PGD, or Guardant Health, another player in the field.
"The only difference is that they are pointing it at this new indication," he said.
Much of the research in the field that has bolstered the growth of these other tests has been based on demonstration of their ability to detect circulating cancer mutations in the blood of patients who already have cancer. This in and of itself is not a representation that the same approach can sensitively detect cancer in those who have not yet been diagnosed.
Asked about research that the company has conducted and whether it has been only on patients with known cancers, or in asymptomatic patients, Arianpour said only that most work in the liquid biopsy field to date has been done in advanced cancers.
"Our test is highly sensitive. We've done various internal studies … and obviously we validated the test under CLIA … and we are working with top cancer institutions both on the hospital and academic side to publish results in the near future," he said.
But defining information on the test's clinical sensitivity and specificity, or more importantly, its false positive rate, has yet to be disclosed.
"False positives can sink any screening test," Diaz explained. "If you tell someone they have cancer and they don't, it's a bad thing, not just emotionally for the patient, but also for the medical establishment because it increases cost of medical care. It can actually be dangerous, too, because patients can be harmed by the tests that they get as a result of a positive finding."
Helmy Eltoukhy, CEO of Guardant Health, a company which markets a sequencing-based test called Guardant 360 that evaluates more than 100,000 loci in 68 genes, also highlighted the importance of knowing a test's false-negative rate in the setting of early cancer detection, where patients at higher risk are looking for a result that can ease their anxiety.
Guardant is also pursuing early detection, but Eltoukhy said that the company is working to develop a platform that will be much more sensitive and comprehensive than its current offering or other technologies now on the market.
"The way we look at it, what is needed for early detection is an MRI, [whereas] this is more like a stethoscope," he said.
Regarding the emergence of early detection testing right now, Eltoukhy said, "I think the good part of this is in empowering the patient with access to information about their healthcare and their bodies and their genomes … but obviously that has to be done in a responsible way … and an informed way in terms of what the limitations of a test are."
According to Diaz, questions about validation don't necessarily mean Pathway's launch isn't a valuable first step. "Now we just need data from thousands of patients," he said.
In the meantime though, he added, "I wouldn't want to tell an individual person what to do … but without that data it would be very tough for a physician to counsel a patient on the meaning of a negative or a positive result."