NEW YORK., Jul 23, 2026 /GenomeWeb/ – Based on data generated in the National Lung Screening Trial (NLST) cohort, cancer testing firm Mercy BioAnalytics believes its lung cancer early detection assay can identify cancers missed by existing low-dose computed tomography (LDCT)-based screening approaches.
While blood-based lung cancer tests have typically been seen as tools for triaging patients to LDCT screening, Mercy is looking to position its Halo lung assay as a test for detecting cancers not found by LDCT and in average-risk populations for which LDCT screening is not currently recommended.
Mercy’s Halo testing platform measures tumor-associated proteins present on the surface of extracellular vesicles (EVs). The company’s tests detect combinations of surface proteins, with, in the case of the lung cancer test, four tumor-associated proteins required to be present on an EV to trigger a positive result. Mercy detects the presence of these protein combinations using a proximity ligation assay in which antibodies to the target proteins are tagged with pieces of complementary single-stranded nucleic acids. When those antibodies bind to their targets, the complementary nucleic acids anneal and produce a nucleic acid strand that can be read out via PCR.
This month, the company and its collaborators published a paper (https://www.nature.com/articles/s41598-026-60259-6) in Nature Scientific Reports detailing the development and initial validation of its lung cancer assay.
Since the work described in the paper, Mercy has evaluated the assay in several additional cohorts, including samples collected by the NLST — a large-scale National Cancer Institute-funded trial that provided key evidence supporting the use of LDCT screening in high-risk individuals — and a collection of high-risk and average-risk individuals from the lung cancer program at Massachusetts-based healthcare provider Beth Israel Lahey Health.
In its work with the NLST cohort, Mercy looked at samples including from 48 individuals with LDCT-detected cancers and matched samples from the same individuals collected in the round of annual screening prior to the round where the cancer was found.
Important to the company’s analysis of the NLST samples is the fact that in the years following the NLST, radiologists changed the framework used to evaluate the likely malignancy of detected lung nodules from the NLST framework, which was highly sensitive but had relatively low specificity, to a framework called Lung-RADS, which was less sensitive but more specific than the NLST framework. This means that a subset of the cancers identified in the NLST would have gone undetected or been detected later when evaluated using the Lung-RADS approach used today.
This allowed the Mercy researchers to evaluate how the Halo test performed compared to the current Lung-RADS framework in detecting nodules identified as malignant in the original NLST analysis. Looking at 48 individuals who had LDCT-detected cancers and matched blood samples collected one year prior, the Mercy test identified 31 percent of lung cancers. LDCT using the Lung-RADS framework identified 8 percent. Meanwhile, in the full set of 96 samples the company used from the NLST, Mercy’s test detected 34 percent of lung cancers while the Lung-RADS framework detected 40 percent, indicating that the two approaches detected substantially different sets of cancers.
Mercy CEO Dawn Mattoon said the results suggest the company’s test could prove complementary to LDTC as opposed to primarily a triage tool.
“We absolutely see the need for alternative screening modalities in the high-risk population,” she said. The company is now working to gain access to a larger set of samples from the NLST cohort, she added.
In its evaluations of the Halo lung test, Mercy has set its specificity at 90 percent, which Mattoon said is higher than would be expected for an initial screening test meant to triage individuals for LDCT.
Business considerations are a key driver of how Mercy hopes to position the test, Mattoon said, noting that a low-specificity triage test would effectively require payors to cover two first-line screening tests.
“It’s our view that a low-specificity test that automatically reflexed into [LDCT], the coverage pathways for that paradigm is hard to see,” she said.
Under the company’s current business plan, Mercy’s initial target market for the test will be average-risk individuals, a group that does not typically qualify for LDCT-based lung cancer screening. In work with Beth Israel Lahey Health, the company showed that at 90 percent specificity, its test detected lung adenocarcinoma in average-risk patients without a history of smoking with 50 percent sensitivity, and 31 percent sensitivity for stage I and II cancers. This was comparable to the test’s performance in Lahey Health’s high-risk cohort (meaning individuals eligible for LDCT screening), where at 90 percent specificity it showed sensitivity of 45 percent for all lung adenocarcinomas and 39 percent for stage I and II cancers.
Mercy plans to launch the lung cancer test in combination with its Halo ovarian cancer test, which is currently available via an early access program. The decision to offer the tests in combination reflects the company’s reimbursement strategy. Currently, Medicare does not cover screening tests unless they have received the endorsement of the United States Preventive Services Task Force. Earlier this year, however, Congress passed a provision (https://drupal.prod.360dx.com/cancer/fda-approved-mced-tests-set-medicare-coverage-federal-spending-bill-passes) making multi-cancer early detection (MCED) tests eligible for Medicare coverage provided they have received US Food and Drug Administration approval. By combining the two tests, Mercy aims to make its assay reimbursable by Medicare as an MCED.
Christine Berg, former chief of the early detection research group at the NCI where she co-led the NLST and a member of Mercy’s clinical advisory board, said that she sees the Mercy lung test as potentially useful in former smokers who are nonetheless not eligible based on their risk profile for LDCT screening.
“I think a blood test could potentially be useful in helping identify some people who may have an early lung cancer so they could go on for further evaluation,” she said.
The test might also find a role in helping clinicians in equivocal situations where they aren’t certain if a lung nodule detected on an LDCT scan requires a biopsy or not.
Applying the test to an average-risk population will likely be more challenging, Berg said, noting that the company has seen some encouraging results with regard to this application but in a small sample set. The average-risk cohort in the Lahey study consisted of 74 controls and 27 cases.
Berg said that in the absence of some sort of risk stratification tool to help identify higher-risk patients in the average-risk population, a test like the Mercy assay would likely need specificity in the range of 99 percent. With up front risk stratification, the 90 percent specificity Mercy has been evaluating its test at could be sufficient, she said.
As required for coverage by the US Centers for Medicare and Medicaid Services , Mercy plans to take both its Halo ovarian and lung cancer tests through FDA. Mattoon said that Mercy is in the process of taking the ovarian cancer test through a modular premarket approval submission and has had the first module of its submission accepted by the agency. She added that Mercy expects FDA to require a post-market approval study for the ovarian test and that it plans to evaluate the lung assay at the same time.
“Since we’re very likely to have to do a post-market study for the ovarian cancer test, we would just have that trial do double-duty basically, and have it serve as the pre-market validation study for the multi-cancer test,” she said.