By Tony Fong
NEW YORK (GenomeWeb News) – While the buzz around human papillomavirus testing has centered on DNA-based testing, a startup firm is looking to carve out a place in the market with protein-based tests that it says offer a critical advantage over DNA tests.
Based in San Jose, Calif., OncoHealth has developed a test that measures the expression levels of two oncoproteins, E6 and E7, that when expressed at high levels may be predictive of patients with HPV who could progress to cervical cancer. In the coming months the firm anticipates launching its test on an ELISA format, but longer-term it plans to move the test onto an automated platform.
The company will be entering an already crowded field and one of the hottest markets in molecular diagnostics, with companies such as Qiagen, Gen-Probe, Hologic, and Roche offering DNA tests for HPV. In the US alone, the HPV molecular testing market is estimated at $300 million.
According to OncoHealth Co-founder and CEO Winnie Wan, DNA-based HPV tests "are in general very sensitive," but because of their low specificity, they have limited use in predicting which patients with HPV will develop cervical cancer.
In a retrospective study published earlier this year in the Journal of Clinical Microbiology, researchers found that for atyptical squamous intraepithelial lesions, DNA-based HPV tests have a specificity of 29 percent. For low-grade squamous intraepithelial lesions, specificity was even lower at 13 percent, and for high-grade squamous intraepithelial lesions, specificity was 4 percent.
OncoHealth's advantage, Wan said, is that its test has higher specificity — though she declined to provide figures — making it a better tool for determining which HPV patient has true disease that can benefit from immediate intervention.
HPV DNA testing made the news recently when the US Preventive Services Task Force recommended against DNA-based HPV tests, either alone or in combination with a Pap test, for women younger than 30 years of age as a screen for cervical cancer because of a high false-positive rate.
"Evidence from good- and fair-quality observational studies indicates that HPV testing generally has a higher sensitivity but lower specificity (i.e., more false-positive tests) than cytology in the detection of CIN2+ and CIN3+," the panel said in its recommendation.
For women 30 years of age and older, the jury is still out, it added. "Evidence supports the use of [liquid-based cytology] or conventional cytology for cervical cancer screening, but more complete evidence is needed before HPV-enhanced primary screening is widely adopted for women aged 30 years and older."
In an e-mail to GenomeWeb Daily News, Svea Lübcke, a spokeswoman for Qiagen, the leading player in the DNA HPV test space, said that "clinical sensitivity is right now far more relevant than specificity," and that the company's Hybrid Capture Technology is about 30 percent to 45 percent more sensitive than cytology-based testing.
Lübcke pointed to a study published last year that showed that in follow up of atypical squamous cells of undetermined significance, the Hybrid Capture Technology is more specific than cytology or colposcopy.
"Overall, specificity of HPV testing increases in women at the age of 30 years and older," Lübcke said. "This is why primary HPV testing is recommended in this age group only."
Rather than testing for DNA, OncoHealth's test targets the E6 and E7 oncoproteins, which because they are "responsible for the suppression of apoptosis in the host," can provide prognostic information and predict progression to cervical cancer, Wan told GWDN in a recent interview.
Being able to predict the progression of HPV to cervical cancer is important because while HPV is a common infection, a relatively low percentage of HPV cases turn to cervical cancer. In the US alone, about 20 million people have HPV, and about 6 million new cases are diagnosed each year, according to the Centers for Disease Control and Prevention.
Usually, the virus clears by itself, but when it doesn't the danger for women is that it will metamorphose into cervical cancer. This year about 13,000 new cases of cervical cancer will be diagnosed, the National Cancer Institute said.
Research into which HPV cases may progress to cervical cancer has focused on strains of the virus collectively known as high-risk HPV, or HR-HPV. Certain HPV types, such as 16 and 18, are highly associated with cervical cancer, but according to Wan less than 30 percent of women with these HPV types actually progress to cancer.
"The whole approach of identifying high-risk HPV is useful for saying who may be at increased risk, but it's not very useful in identifying true disease since most HPV infections will self-resolve," Wan said. "So we basically steer away from distinguishing between high-risk or low-risk [virus], but rather focus on two critical oncoproteins that play significant roles in disease progression."
A small number of firms including InCellDx and Gen-Probe also have tests that are based on E6 and E7, but instead of the proteins they are based on the E6 and E7 messenger RNA.
Gen-Probe claims in the package insert for its Aptima HPV assay, which was cleared by the US Food and Drug Administration in October, that the test has a specificity of 95.2 percent. Michael Watts, a spokesman for the company added in an e-mail to GWDN that that figure is relevant for the "adjunct portion of our study … But keep in mind that these are verification-adjusted estimates, and you can't compare specificity (or sensitivity) estimates across studies with different protocols and patient populations."
Regardless, according to Wan, because OncoHealth's test directly targets the oncoproteins themselves, detection of the virus is more direct and requires less expensive equipment and methods than E6/E7 mRNA tests.
Colposcopies also are used for the diagnosis of cervical cancer, but if the lesions are not taken directly from tissue that is infected, the result may come back false-negative, she said. In addition, the procedure is invasive and expensive, costing about $500.
OncoHealth's goal is not to replace colposcopies, but to identify those women who truly need the procedure.
"Our objective is to provide a test that can minimize the clinically insignificant population [that is] subjected to the invasive procedures and repeat testing," that is currently being practiced, Wan said. In the process, OncoHealth's test, called OncoHealth Direct E6/E7, should also save healthcare costs.
ELISA Today, Automation Tomorrow
While OncoHealth was launched just two years ago, its beginnings are rooted in another firm founded six years ago by Shuling Cheng called NeoDiagnostic Labs to develop biomarkers. Wan was recruited by Cheng to commercialize NeoDiagnostic's technology.
The decision to spin out OncoHealth as a separate company was made, Wan said, because doing so would make creating a financial infrastructure to focus solely on commercializing its HPV test "a lot cleaner." Today, OncoHealth has the exclusive worldwide rights to NeoDiagnostic's technology for the E6 and E7 biomarkers.
The company is currently conducting clinical studies for its test, which it plans to offer initially as an ELISA assay, and has analyzed about 3,000 patient samples.
Because of ELISAs' simplicity and lack of need for expensive equipment, such a format would make it accessible to labs not only in the US but in developing countries, increasing the potential reach of the test, Wan said. Additionally, an ELISA format would allow OncoHealth's test to be used as a screen as well as a diagnostic.
Unlike other ELISA tests, OncoHealth's test does not require the cells to be lysed or the protein to be extracted, and detection can be done in a whole cell, enabling higher specificity, she said. The company anticipates making its technology available by offering analyte specific reagents to CLIA labs so that they can develop their own tests. OncoHealth does not have its own CLIA lab.
The company also plans to pursue a CE mark so it can make its test available as an ELISA assay in Europe.
In addition to an ELISA format, OncoHealth plans to develop the HPV test in an immunohistochemistry format, an immunocytochemistry format, and as a flow cytometry-based test.
The firm has demonstrated that the E6 and E7 biomarkers can be implemented on the four different platforms, and "from a scientific standpoint, it demonstrates the robustness of the biomarkers" and OncoHealth's methods, Wan said.
As an ELISA and/or ICC test it would be used for screening and diagnostic applications, while the test would be useful for confirmation of biopsies as an IHC test. A flow cytometry format would allow for confirmation of cytology results.
In the increasingly crowded HPV/cervical cancer testing market, Wan acknowledged that getting OncoHealth heard over the din will be a challenge. The company plans first to conduct and publish large studies and to get thought leaders to adopt its product in order to gain credibility.
For screening purposes, the test would need to be transferred to an automated platform, and in order to align its tests with instruments already placed in clinical labs, OncoHealth is looking to partner with platform manufacturers to make the test available on those instruments and to help fund the clinical studies needed for regulatory approval of the tests to run on such a platform. The company is in discussions with several platform firms though Wan declined to identify them.
While OncoHealth is focused on HPV and cervical cancer, the virus also is associated with other cancers, such as anal cancer and oral cancer, whose rates of incidence are on the rise. Wan said that with some minor modifications, OncoHealth's test lends itself to diagnostics for those cancers, and she added that the company is collaborating on a study investigating anal cancer.
OncoHealth generates a small amount of revenues from selling antibodies to research labs but has depended on investments as a source of funding. Since its founding, it has raised $2.1 million, including a $1.6 million Series A round of financing earlier this year. In the spring it plans to conduct a further round to finance the commercialization of its test and continued development, Wan said.