NEW YORK – As startup NanoPin Technologies ramps up sales of its blood-based test for difficult-to-detect tuberculosis cases, the firm is also paving the way for a multiplex TB and HIV test that could help healthcare providers identify and manage treatment of patients with the two coinfections.
NanoPin CEO Thomas Tombler said the firm is ready to accept samples at its CLIA-certified lab in New Orleans for the NanoDetect-TB test to detect active Mycobacterium tuberculosis infections that would be missed by the sputum-based tests typically used for TB diagnosis. The test is the firm's first product to go to market.
"We have an ultra-sensitive method to detect active tuberculosis with a value proposition including early detection and the ability to detect it in basically anybody, and that means whether it's an adult with pulmonary tuberculosis or an infant with tuberculosis in the brain," he said.
Children and people coinfected with HIV can have difficulty producing sputum, and patients with extrapulmonary TB infections may not have the bacteria in their lungs. Tombler said NanoDetect-TB also allows detection of active TB potentially weeks to months earlier than other methods, with the greatest gap identified in a study of infant patients.
The TB assay is also the foundation for the firm's in-development NanoDetect-TB/HIV multiplex assay for simultaneous detection of HIV and TB with quantitation of viral and bacterial loads. Patients with HIV are at higher risk of TB infection, which is the leading cause of death among people with HIV, according to the World Health Organization. Developing new biomarker-based TB tests that use non-sputum samples has been a long-term priority for public health officials, according to a WHO report.
Tombler said simultaneous quantitative testing for both HIV and TB can help healthcare providers monitor HIV patients for TB coinfections as well as monitor treatment of patients with confirmed coinfections in case the therapy administered for one pathogen leads to surging levels of the other. While he said the market already has good tests for HIV infection, the company sees an advantage in using its test for repeated testing to monitor patients following an HIV diagnosis.
NanoPin's tests are liquid chromatography-tandem mass spectrometry-based assays that use proprietary monoclonal antibodies to quantify peptides derived from HIV-1 p24 and M. tuberculosis 10-kDa culture filtrate protein in trypsin-digested serum or plasma. The firm inked a deal in 2020 with Thermo Fisher Scientific for the collaborative development of LC-MS workflows for blood-based infectious disease detection, and NanoPin performs its tests today on Thermo Fisher's Altis MD mass spectrometer.
Tony Hu, chair of biotechnology innovation at Tulane University and cofounder of NanoPin with Tombler in 2017, said the trypsin digestion process used in the assays allows detection of HIV and TB antigens that are bound by antibodies and would be undetected in blood by other antigen tests. The tests also incorporate a species-specific peptide for TB detection, which avoids the false positives that can occur in antigen tests that identify biomarkers that are shared with other mycobacteria, he said.
NanoPin published in 2021 results of a study that indicated that, among HIV-infected infants, the company's quantitative test for M. tuberculosis CFP-10 virulence factor had 100 percent sensitivity for culture-confirmed TB and 84 percent sensitivity for unconfirmed but suspected TB, and it performed with 93 percent specificity in HIV-positive patients. The test was able to detect the only culture-confirmed TB case in an HIV-negative patient and had 75 percent sensitivity for patients with suspected TB. The test also performed with 96 percent specificity in HIV-negative patients. In 2021, the firm also received a $2 million Small Business Innovation Research grant from the National Institutes of Health.
Last month, an international team of researchers led by Hu published in the journal Clinical Chemistry the results of a study using cryopreserved plasma samples from 23 adults in Kenya with active TB and 11 asymptomatic contacts, 13 children from southern Africa with TB and HIV coinfection and four controls with perinatal HIV-1 exposure but no HIV or TB infections, and serial plasma samples from five patients with acute HIV infection. The authors wrote that the test identified HIV infections in adults with 86 percent sensitivity and in children with 89 percent sensitivity, while it identified TB in adults with 100 percent sensitivity and children with 89 percent sensitivity. The researchers said the test performed with 100 percent specificity for HIV and TB in adults and children.
Hu said NanoPin has started recruitment for follow-up studies through a multisite clinical trial of the assay in collaboration with healthcare providers in Houston, Miami, New York City, and New Orleans.
According to the Clinical Chemistry study authors, the test is needed because acid-fast bacilli smear and culture tests, as well as Cepheid's Xpert MTB/RIF assay for detection of TB and rifampin resistance-associated mutations, can have low sensitivity to samples from patients with HIV/TB coinfection. Hu said those sputum-based methods remain the gold standard for TB detection. Cepheid did not respond to a request for comment, but the WHO recommends nucleic acid amplification or biomarker-based testing to confirm TB infections such as the use of tests from Cepheid, MolBio Diagnostics, Eiken Chemical, Becton Dickinson, Bruker/Hain Lifescience, Roche, and Abbott.
Bobby Brooke Herrera, assistant professor and researcher of infectious disease diagnostics and vaccines at the Rutgers Global Health Institute, described the Tulane team's study results as a promising first step and said he would like to see further studies to validate the test. Herrera is not connected with NanoPin.
"There would need to be trials that would allow testing in real-world settings, meaning let's put an instrument in Kenya," he said, noting that many of the frozen samples used in the study were sourced from patients in Kenya.
Hu said in response that such a study would be feasible, and his collaborators at the Kenya Medical Research Institute in Nairobi have the mass spec equipment needed for such studies.
Herrera added that HIV patients who are on antiretroviral therapy are three times more likely to die during TB treatment. Making a multiplex test for HIV and TB ubiquitous in the regions that need it the most requires striking a fine balance of delivering the sensitivity required while reducing the cost, complexity, and instrument requirements of such a test, he said.
Hu said his lab has been working to reduce the cost of the HIV and TB multiplex assay and have been able to drive down the reagent cost to less than $1 per test, and he estimates it could be profitable to run the test at a price as low as $15-$20 per test.
As for the NanoDetect-TB test, Tombler said his firm plans to release pricing for the test in January and the company is in discussions with payors about potential reimbursement rates. He said the NanoDetect-TB and NanoDetect-TB/HIV tests are currently priced per project.
The Lancet Commission reported in 2021 that about 35 percent of people with tuberculosis are undiagnosed as are about 46 percent of people with HIV due to lack of access to diagnostics among almost half the global population. Following advocacy coordinated by MSF Access Campaign and Treatment Action Group to lower the price of tests, Danaher said in September it would provide Cepheid's Xpert MDT/RIF Ultra diagnostic test cartridges to the Global Fund to Fight AIDS, Tuberculosis, and Malaria and to less-developed countries at Cepheid's cost of $7.97 per test.
Cepheid also said this spring that it could expand its TB testing lineup to include a fingerstick host response test that would measure three messenger RNA genes and stratify patients as positive, high risk, low risk, or negative for TB.
Other test developers are working on low-cost tests or services for TB that augment the existing lineup. Researchers from the Karolinska Institute and partners from Rutgers University, Yale University, Stanford University, and Nanjing Agricultural University said in September that they had developed a method of creating rapid, molecular diagnostic tests at a cost of less than $5 per test, and they expect to commercialize the technology within a few years. ReadyGo Diagnostics has also partnered with Gemini Laboratories to develop a saliva-based test to rule out tuberculosis infection at an expected per-test cost of less than $5.
QuantuMDx is developing a sample preparation system that employs an electrical charge to enrich sputum samples and provide easier TB identification through visual identification or qPCR testing. BioMérieux and Oxford Nanopore Technologies are also partnering on a sequencing-based platform for TB drug resistance testing. Co-Diagnostics said earlier this year that it received a $1.3 million grant from the Bill and Melinda Gates Foundation toward development of tuberculosis tests that will run on the firm's Co-Dx PCR Home Platform.
Tombler said that while NanoPin is currently focused on a centralized testing model that uses shipments of frozen plasma or serum samples, it is also laying the groundwork for a potential submission to the US Food and Drug Administration for marketing clearance. The firm developed NanoDetect-TB as a kitted assay that it will use for clinical testing and for studies to support such a regulatory submission. Hu said the firm plans to seek 510(k) marketing clearance.
NanoPin is also working to develop partnerships in China, where Tombler sees a much larger market for diagnosis of active tuberculosis compared to the US and a potential market for upward of millions of tests per year between diagnosis and treatment monitoring.
"China, of course, is a market that is very much in need of an active tuberculosis test, and that's because the latent [TB] population in China is very high and it's not feasible to treat all the latent tuberculosis," Tombler said. "After China, we look at Southeast Asia, India, Africa, and South America."
Hu is also working on a second-generation point-of-care version that uses nanopore-based capture and detection, an easier-to-perform testing method that he and coauthors described last year in the journal Nano Today. Future generations of the test also could shift to use of CRISPR-based detection of cell-free TB DNA, a method he reported last year could detect infection with high sensitivity in HIV-infected children.
Tombler said the company is also considering expansion into veterinary applications that would use versions of the test to detect tuberculosis strains in nonhuman primates and cattle, and the firm is also developing non-tuberculosis Mycobacterium tests that could be used to help respond to an uptick in cases in cities such as Houston, Miami, San Diego, and New York.
The firm is for now working toward beginning research-use-only testing of NanoDetect-TB/HIV and form partnerships to bring in clinical samples to continue the studies needed to bring the test to market.