A new method of detecting breast cancer has been developed that looks for an exosome biomarker for breast cancer that is found in tears. The technology was developed by a team of researchers at Kobe University and System Instruments Co., Ltd.
Currently, breast cancer is usually diagnosed using mammography, and while this method of diagnosis is accurate, the equipment required is bulky and it takes time to arrive at a diagnosis. The patient must have a mammography, then the results need to be interpreted by at least two specialists. A simple test using easy to obtain bodily fluids would not only help speed up diagnosis, the test could be conducted in a wide range of settings, and could even be self-administered in a patient’s home.
Exosomes have shown great promise for use in liquid biopsies to detect cancer. Exosomes are extracellular vesicles, which previous research has shown are involved in the development of malignant tumors and cancer metastasis. Exosomes are therefore important biomarkers for cancer and are often used in liquid biopsies. While exosomes have great promise for use in easy-to-administer, rapid, non-invasive diagnostic tests, one of the problems is exosomes require extensive preprocessing.
The new technology developed by the Kobe University researchers solves this problem. The technology, named TearExo, involves a glass chip that contains an antibody to the cancer cell exosome that recognizes the surface proteins of the exosome. A reporter molecule then fluoresces when the exosome is present. The fluorescence is detected by an automatic exosome analyzer which is used to give either a positive or negative result. The researchers report that TearExo is ultra-sensitive and can detect around 50 exosomes in a 100µL tear sample in around 10 minutes. In contrast to other exosome detection methods, there is no preprocessing required. The tear samples were collected from patients using a strip of filter paper (Schirmer test).
In the tests, the researchers found clear differences between tear samples taken from healthy patients and patients diagnosed with breast cancer. The researchers also found that after a patient has had a mastectomy, the results of the test were comparable to healthy patients.
The tests could therefore be used to diagnose patients quickly and easily, and for use during follow ups on patients who have undergone treatment to monitor progress and determine whether the treatment has been effective.
The researchers will now perform a much larger test of clinical samples to more accurately determine both the sensitivity and specificity of the test. The researchers hope to apply for a license to approve TearExo as an in vitro diagnostic test within a year.
You can read more about the study in the paper – Antibody-conjugated signaling nanocavities fabricated by dynamic molding for detecting cancers using small extracellular vesicle markers from tears – which was recently published in the Journal of the American Chemical Society DOI: 10.1021/jacs.9b13874