Testing the Future
Petricoin and Liotta, also undeterred by critics, are moving steadily forward, albeit separately from Correlogic. They’re assessing their own ovarian-cancer test in a clinical trial for women in remission, to detect return of the disease. They intend to submit the method for FDA review and to license the related technology nonexclusively to any company interested in offering it.
The two scientists are also preparing similar tests for pancreatic, lung, and prostate cancers. They envision a future in which a small blood sample, periodically drawn in the doctor’s office, will reveal a complete image of the current disease status of the entire body. “Our goal is to show that in fact you can come up with a protein pattern that can discriminate disease and for the [National Cancer Institute] to take that all the way to FDA approval,” says Petricoin.
But the first diagnostic test based on protein profiling will probably be an ovarian-cancer test from Ciphergen, the company whose machine started it all. Ciphergen is not using a pattern per se but is instead sticking with its initial, more conservative approach: using protein patterns to find markers that are then individually identified and validated for their ability to distinguish cancer from noncancer.
The company is fashioning tests that use mass spectrometry to detect these specific markers, as opposed to the overall protein pattern. Ciphergen is also working on pancreatic- and prostate cancer tests, but its ovarian-cancer test-based on three protein markers-is the most advanced. “Our goal is to commercialize the test by the end of this year or early next year,” says Gail Page, president of Ciphergen’s diagnostics division.
Whether it will open the floodgates for similar tests depends on how well it performs. But Ciphergen is committed to using protein profiling as the basis for new and better cancer diagnostics. “We believe it will be the wave of the future,” says Eric Fung, Ciphergen’s director of clinical affairs and one of the originators of the ovarian-cancer test. “There is a transition from single markers to multiple markers, andsomeday it will evolve to patterns,” he says. “It’s my personal view that we may end up there, but we’re not there yet.”
Many enterprising scientists and companies, however, are betting that patterns will be ready for use within just a few years. And they expect patterns to diagnose cancer earlier, more accurately, and more reliably than a limited set of known markers like Ciphergen’s, however well chosen. Wright, for instance, though now retired and playing an advisory role, still continues his quest for an accurate cancer test based on pattern recognition. Four decades of failure have taught him to be cautious, but he can’t hide his excitement. “It will take several years for us to know whether this can be definitely proven to be useful,” he says. Still, he adds, “It’s very exciting, highly promising.”
Tests based on protein patterns, if they work, could help to save millions of lives. But as Wright and other cancer researchers well know, they aren’t the last word in cancer diagnosis. “There’s no magic elixir,” says Petricoin. “Nothing’s going to replace a smart doctor working with a patient.”