The technology is a step toward personalized medicine and could help standardize breast cancer diagnosis around the world, according to researchers at Washington University School of Medicine in St. Louis, who led the test’s development.
The research team, including collaborators at the University of North Carolina, the University of Utah and the BC Cancer Agency in Canada, designed a test that categorizes breast tumors into one of four main types by looking at the expression of 50 genes. The four types are luminal A, luminal B, HER2-enriched and basal-like. Each subtype has a distinct genetic signature and requires a different treatment approach. These subtype data are then combined with a standard pathology variable to deliver a “risk of recurrence” score that predicts the likelihood of that patient’s disease returning within the next 10 years. In this way, clinicians now may be able to accurately identify those low-risk patients for whom standard hormone therapy is sufficient.
The new test removes some of the subjectivity that goes into breast cancer diagnosis, which still involves looking at the cells under a microscope and deciding on likely outcome based on visual cues on how aggressive the tumor is likely to be.
“Breast cancer diagnosis and prognosis by looking at samples under a microscope remains quite variable and subjective – often pathologists do not agree,” said oncologist Matthew J. Ellis, MB, BChir, PhD, a co-inventor of the test. Ellis also treats breast cancer patients at Siteman Cancer Center at Barnes-Jewish Hospital and Washington University. “With this test, we are moving toward a standardized diagnosis based on the genetics of the tumor. The test determines which type the patient’s cancer is most similar to. And the closer it is to a subtype called luminal A, the better the outcome.”
Patients with the luminal A subtype have a low risk of recurrence and do well with long-term anti-hormone therapy that reduces or blocks estrogen, which fuels these tumors. But the other tumor types may require more aggressive measures to prevent relapse, including chemotherapy and sometimes investigational drugs.
“This is a very important step down the road toward personalized medicine, and our approach allows us to make this test available to a global market,” said co-inventor Charles M. Perou, PhD, of the University of North Carolina at Chapel Hill.
The test, called Prosigna and manufactured by NanoString Technologies, comes with a machine and kit, so patients’ tumor samples do not have to be sent to a specific laboratory for analysis. The test is being distributed to pathology labs around the world and also is approved for use in the European Union.
The universities jointly hold a pending patent on the technology behind the Prosigna test and have licensed the technology to Bioclassifer LLC. The investigators have joint ownership of Bioclassifer LLC, which licensed the technology to NanoString Technologies. The financial interests of the investigators and their universities are managed in accordance with applicable conflict-of-interest policies and regulations.
Washington University School of Medicine’s 2,100 employed and volunteer faculty physicians also are the medical staff of Barnes-Jewish and St. Louis Children’s hospitals. The School of Medicine is one of the leading medical research, teaching and patient care institutions in the nation, currently ranked sixth in the nation by U.S. News & World Report. Through its affiliations with Barnes-Jewish and St. Louis Children’s hospitals, the School of Medicine is linked to BJC HealthCare.