Mehmet Toner wants cancer doctors to be able to see what he can see.
Most oncologists rely on imaging tools like CT scans, and perhaps only a single biopsy, to learn what they can about patients’ tumors and the biological traits of their cancer cells. Toner, a biomedical engineering specialist, says he can track the evolving nature of an individual’s cancer cells in real time—as they mutate or respond to treatment—by capturing the tumor cells that have broken loose to circulate in the patient’s blood.
Toner’s work with colleagues at the Massachusetts General Hospital Center for Engineering in Medicine recently stirred up renewed interest in the potential of circulating tumor cells for a range of uses. They could be a future focus of routine diagnostic tests, a guide to the development of personalized cancer drugs, and a research tool that could unveil the mysteries of metastasis.
Toner’s window on cancer comes from a microfluidics-based system called the CTC-iChip that he and his team developed at Massachusetts General in a three-way collaboration with Veridex of Raritan, NJ, a diagnostics division of Johnson & Johnson, and Veridex’s affiliate Janssen Research & Development. The device plucks out the very few circulating tumor cells, or CTCs, from among the billions of other cells floating in the blood.
Those tumor cells could give doctors and clinical trial investigators a series of status updates over the course of a patient’s diagnosis and treatment, Toner says. CTC testing could provide information about the changing genetics of tumor cells to steer the use of cancer therapies that are targeted at specific mutations. And this could be done without additional invasive biopsies, Toner says.
“Doing multiple solid tumor biopsies is very difficult,” says Toner, director of the BioMicroElectroMechanical Systems Resource Center at Massachusetts General’s Center for Engineering in Medicine. “This will be what we call a liquid biopsy.”
The theoretical promise of CTC testing has captivated researchers and science buffs as well as profit-seeking venture capital firms. The CTC-iChip drew a flurry of media coverage after Toner’s team published early study results on the system in Science Translational Medicine during the annual meeting of the American Association for Cancer Research (AACR) that ran through April 10.
But as the AACR meeting wrapped up, a prominent venture firm partner who had invested in a CTC testing startup, Bruce Booth of Cambridge, MA-based Atlas Venture, said in a rueful blog post that the technology may not be ripe for commercial success for another five to 10 years. Booth said his firm’s portfolio company, Waltham, MA-based On-Q-ity, is folding up and selling the last of its intellectual property assets this month—his first total write-off in nine years in the venture capital business.
Booth still thinks he was right about the eventual promise of CTC testing—but not the market timing. It would have taken On-Q-ity years of expensive research to prove that a promising benchtop assay could be a marketable product used by doctors in clinical practice, he concluded.
“The capture and characterization of CTCs will be an important part of oncology care in the next decade. This I’m fairly sure of, and all the news from AACR earlier this week about ‘liquid biopsies‘ supports this premise,” Booth wrote. “But the reality is it’s a research-stage story right now, and in diagnostics (unlike drugs) it’s hard to get paid for research-stage stories.”
Mehmet Toner, however, is hoping that doctors will have his team’s CTC-iChip in their hands before very many years pass. His most fervent goal is to see the CTC test used as a sentinel assay to detect cancer very early, before tumor masses appear in imaging tests—by which point it may be too late for a cure. The device was developed in a joint effort with Veridex, which currently has the only FDA-approved in vitro diagnostic assay for CTC capture and counting. Veridex has the right to acquire the CTC-iChip and commercialize it.
“They really know the territory,” Toner says. “They’re the right partner.”
Veridex’s studies indicate that its CTC testing system already on the market, CellSearch, can help doctors predict the long-term survival prospects of patients in three major cancer types by tracking the total counts of circulating tumor cells at intervals before and after treatment.
The company launched its collaboration with the Massachusetts General team in January of 2011 to go further than merely enumerating the captured tumor cells. Greater diagnostic power could come from
