Biodesix this week reported results from the first prospective clinical trial of its proteomic lung cancer test Veristrat.
Presented at the American Society of Clinical Oncology's annual meeting, the trial findings demonstrated that the test is able to identify lung cancer patients likely to respond well to treatment with Roche/Genentech's EGFR inhibitor Tarceva (erlotinib) in the second-line setting.
Led by Vanesa Gregorc, an oncologist at the University Hospital San Raffaele in Milan, Italy, the trial – titled PROSE – examined 285 advanced non-small cell lung cancer patients who were stratified by ECOG-performance status, smoking status, and blinded pre-treatment VeriStrat classification and then randomized to receive erlotinib or chemotherapy at standard doses.
The trial found that patients classified by the test as Veristrat "poor" fared significantly worse on erlotinib than chemotherapy, with the erlotinib-treated group showing median overall survival of three months compared to six months for the chemotherapy-treated group.
Patients classified as Veristrat "good," on the other hand, did equally well on either chemotherapy or erlotinib.
The choice between chemotherapy and erlotinib is a key decision facing physicians and patients in second-line lung cancer treatment, noted Jennifer Hedrick, senior director of marketing at Biodesix. The PROSE trial results indicate that Veristrat could prove useful in distinguishing between patients for whom erlotinib should and should not be an option she told ProteoMonitor.
"For Veristrat 'good' patients, you definitely have two treatment options you can choose from, and for the Veristrat 'poors,' they should get chemotherapy," Hedrick said.
Since launching Veristrat in 2009, Biodesix has performed the test on around 5,000 patients, offering the test out of its CLIA-accredited lab. Based on the company's ProTS mass spec platform, the test combines MALDI mass spectrometry with a set of algorithms to predict response to EGFR tyrosine kinase inhibitor therapy based on patients' proteomic profiles.
Biodesix has previously published a number of retrospective studies on Veristrat, but this is the first prospective trial evaluating the test and, as such, could prove key in driving physician adoption.
Indeed, Nathan Pennell, director of the Lung Cancer Medical Oncology Program at Cleveland Clinic, told ProteoMonitor this week that based on the PROSE data he would now consider ordering Veristrat for patients in his practice when warranted.
"I've been in discussions with the company about the test, and until this trial I would say that I didn't trust the [retrospective] results enough to use it in clinical practice," said Pennell, who is not affiliated with Biodesix or the PROSE study authors. "But after the study I am convinced that the test does what it says it does, which is pick patients in whom you should give second-line chemotherapy rather than second-line Tarceva."
"Their retrospective data was fairly convincing but until it had actually been shown prospectively in patients I was skeptical," he added. "But I think they have done that [now]. So I do think there will be situations where I will order the test."
Pennell noted, however, that the market for the test in second-line lung cancer would be "fairly small," observing that there is currently a split within the community regarding whether to offer erlotinib second-line or to simply treat all such patients with chemotherapy and reserve erlotinib for third-line treatment.
For physicians choosing the latter route – a group that Pennell said at the moment probably represents the majority of oncologists – Veristrat would not be of use.
Acknowledging this, Paul Beresford, Biodesix's vice president of business development and strategic marketing, suggested that one component of the company's strategy for driving adoption of Veristrat was encouraging physicians to consider erlotinib instead of chemotherapy as a second-line treatment.
He cited a recent study funded by the company that examined how Veristrat test results affected doctors' decisions regarding whether or not to treat lung cancer patients with erlotinib (PM 4/5/2013). The study surveyed 710 physicians treating NSCLC patients who ordered 2,822 tests over a period stretching from August 2011 to November 2012, finding that roughly 40 percent of them changed their patient treatment plans based on Veristrat results.
"That is very strong data speaking to the fact that a lot of doctors will actually start changing their behavior in the clinic to using erlotinib in the second line if [a patient] is a Veristrat 'good'," Beresford told ProteoMonitor.
Some recent studies, however, have suggested that chemotherapy may be superior to erlotinib as a second-line lung cancer treatment. For instance, the Docetaxel and Erlotinib Lung Cancer (DELTA) trial presented at ASCO this week found that second-line treatment of advanced non-small cell lung cancer with docetaxel offered improvement in progression-free survival compared to treatment with erlotinib.
Beresford noted, however, that while the DELTA trial showed the benefit of chemotherapy compared to erlotinib in terms of PFS in the EGFR wild-type population, this benefit didn't hold up with regard to overall survival.
"PFS is an important endpoint in second-line lung cancer," he said. "But certainly the gold standard is overall survival, especially in later lung cancer. So while certainly people are considering the results of this trial, I don't think it is borne out from an overall survival standpoint."
Howard West, an oncologist at Seattle's Swedish Cancer Institute, told ProteoMonitor, that use of PFS as an endpoint was "a real shortcoming of the [DELTA] study." However, he said, despite this, the ultimate takeaway from the study is "that you could defensibly give erlotinib because survival is the same, but it is not a preferred option."
"It basically leaves erlotinib as a defensible but sub-optimal approach for second-line patients" compared to chemotherapy, he said.
Viewed from that perspective, the Veristrat PROSE trial "was good at answering a question that isn't relevant," West said. "I just don't see it as practice changing," he added.
Yet, as Cleveland Clinic's Pennell demonstrates, while doctors who offer erlotinib as a second-line alternative to chemotherapy may be in the minority, they do exist. And, for such practices, Veristrat, bolstered by the prospective data from the PROSE study, could prove useful.
"I think the trial was very interesting, and from what I can see it was a well done design, designed to show exactly what [Biodesix] wanted to show, and they got the positive result," Pennell said. "So, it probably won't be something I do a lot, but there will be patients with which I will be using Veristrat."