NEW YORK (360Dx) – CellMax Life has publicized some of the first data that speaks directly to the sensitivity and specificity of its circulating tumor cell-based colorectal cancer test, which is currently only available through its lab in Taiwan, but which the company plans to now bring to the US market.
Researchers are presenting the data at the American Society for Clinical Oncology Gastrointestinal Cancers Symposium in San Francisco later this week. Funded by Taiwan's Ministry of Health, the study examined samples from 620 individuals who were either visiting the hospital for a routine colonoscopy, or who had a confirmed colorectal cancer, concluding that the CTC approach could detect colorectal cancer at an early stage, in some cases a precancerous lesions, with an overall accuracy ranging from 84 to 88 percent.
Atul Sharan, CellMax Life's co-founder and CEO, said this week that the company believes that it can reduce the price of its test below $200, and the firm has highlighted low cost, as well as ease-of-use, as drivers for what it hopes will be successful adoption as a screening tool.
The company has argued that compliance with current modes of colorectal cancer is lower than it should be, leading to cancers being detected in late stages when survival rates are poor. It is presenting the data this week as evidence that the sensitivity of its test is high enough to offer an alternative to existing stool-based assays.
In the study being presented this week, a team led by Wen-Sy Tsai, a physiatrist at Taiwan's Chang Gung Memorial Hospital, collected blood samples from 620 individuals who CellMax said were either coming to the hospital for routine colonoscopies or had confirmed colorectal cancer.
Amongst the total study population, 438 people had either adenomatous polyps (pre-cancerous growths) or early- to late-stage colorectal cancer based on the results of their colonoscopies. The remaining study participants had no signs of pre-cancerous growths or colorectal cancer and served as a control group.
Overall, 111 of the 438 positive colonoscopy cases had precancerous lesions, and the other 327 had stage I or higher cancers.
CellMax analyzed patient samples in its Taiwan clinical lab, and the researchers then compared the reports to each individual's colonoscopy result. Based on this analysis, the investigators calculated that the sensitivity of the assay ranged from 77 percent for detecting pre-cancerous lesions to 87 percent on average for stage I-IV cancers. Specificity for the test was 97 percent.
Based on the data, CellMax's test appears to outperform the sensitivity and specificity of fecal occult blood testing (FOBT), a guideline-recommended stool test for colorectal cancer screening, which has shown about 74 percent sensitivity in detecting stage I-IV cancers and about 95 percent specificity, but no more than 40 percent sensitivity in the detection of precancerous lesions.
According to Sharan, surveys of patients have reported a strong preference for blood tests over stool-based screening tests among relevant populations. Therefore, if the test's performance is accurately represented by the study results shared this week, it would offer an attractive alternative.
The CellMax test also looks to be more accurate than previously reported blood-based tests, according to the new data.
In 2016, the FDA approved Epigenomics' Epi proColon, a PCR-based test that detects methylated Septin9, a biomarker that has also been incorporated into laboratory-developed assays.
But that test has struggled to gain a foothold. The USPSTF, for example, issued an updated recommendation statement on colorectal cancer screening in late 2016, in which it warned against the test's low sensitivity. Researchers have reported up to about 68 percent sensitivity and 80 percent specificity for the assay.
Investigators who led the study of CellMax's test this week wrote in an email that Epi proColon also suffers in detecting precancers compared to later-stage disease, something that they believe distinguishes the CTC-based assay.
Aside from blood-based tests, a 77 percent sensitivity in detecting precancerous lesions also supersedes what has been reported for Exact Sciences' Cologuard, a molecular test performed on fecal samples that has already been cleared by the US Food and Drug Administration and has reimbursement from the Medicare program as well as some major commercial payors.
Cologuard offers about 92 percent sensitivity in detecting stage I-IV cancers, and 94 percent in stages I and II only. But in precancers, the company reports only 42.4 percent detection overall, or up to about 69 percent in high-grade dysplasia.
Exact Sciences' stock dropped as much as 12 percent this morning after the announcement yesterday of the CellMax data, but several Wall Street analysts quickly issued notes questioning the bearing that the results from CellMax's small study could possibly have on Exact's prospects. The company also echoed many of these same caveats in a phone call today.
For one, several analysts said, the CellMax study was small, compared to the research supporting Cologuard. And importantly, it appears to represent a very different population than the actual colorectal cancer screening population. Because of that, the results can't necessarily be extrapolated as representative of how the test would perform in clinical practice.
In CellMax's study, 70 percent of the patients had cancer or precancer. In comparison, in the DEEP-C study of Cologuard, only 6 to 8 percent of a 10,000-individual cohort had cancer or pre-cancer. Based on the fact that Cologuard itself showed higher performance in a non-screening population than it did in its more representative study, one could expect that the same might be true for CellMax's test.
Analysts also argued that Exact Sciences was only able to obtain reimbursement for Cologuard after this extensive trial, and its subsequent receipt of FDA clearance for the test.
But according to Sharan, CellMax is not planning to pursue FDA approval its own the test in the US and doesn't expect to depend on reimbursement by payors, at least not right away. Instead, the company is positioning the test as an LDT and hoping to price it at a point where customers would be willing to self-pay, a strategy it already employs in Asia.
In the meantime, the relative performance of the test compared to standard fecal analyses, other blood-based tests, or to Cologuard, is far from defined based only on the data presented this week.
Even if the CTC method cannot outperform Cologuard, there would still be a possibility that CellMax could argue that the assay has clinical utility based on the fact that more people would be willing to take a blood-based test than a fecal test. But Exact Sciences argued that its own data suggests that there is much less user hesitancy to comply with screening recommendations using its test than there is for colonoscopy.
Whereas less than half of people who are recommended to undergo a colonoscopy go on to get one within a year, more than 2/3 comply with Cologuard, the company has said.
J.P. Fielder, director of corporate communications at Exact Sciences, added today that the company has also reported about 90 percent patient satisfaction with its test.