“Immune checkpoint molecule” is a general term for the multiple molecules (proteins) that help maintain the body’s immune homeostasis1 by activating or suppressing the immune function. Immune checkpoint molecules are known to be involved in autoimmune diseases2 and cancer immune escape.3
Recent years have seen the establishment of cancer immunotherapy as a new cancer treatment method. In this method, antibodies that combine with immune checkpoint molecules are administered to cancer patients and that inhibit the immunosuppressive function to reactivate immunity. As this approach is recognized to be effective for various types of cancer, many pharmaceutical companies are developing therapeutic drugs. In 2018, Tasuku Honjo, distinguished professor at the Kyoto University Institute for Advanced Studies, and Dr. James P. Allison of the MD Anderson Cancer Center at the University of Texas received the Nobel Prize in Physiology or Medicine by proposing the use of immune checkpoint molecules in cancer treatment.
Cancer immunotherapy has been shown to produce strong therapeutic results in patients who have not seen therapeutic results with conventional anticancer drugs. However, the advance selection of patients likely to experience drug efficacy has been difficult. Also, various immune-related adverse events can occur, so a search had been underway for a biomarker to predict therapeutic results and the presence of adverse events.
When studying the body’s immune function to connect diagnosis and prognostic testing for cancer and autoimmune diseases, Professor Honjo noted that some of the immune checkpoint molecules (PD-1, PD-L1 and CTLA-4) normally present on the cell surface membrane were present in the blood as soluble immune checkpoint molecules (sPD-1, sPD-L1 and sCTLA-4). Many researchers had sought to verify a relationship between cancer and immune disease and soluble immune checkpoint molecules present in the blood, but accurately measuring such molecules had been difficult because of the small quantities present. Since 2013, Professor Honjo and Sysmex have been conducting joint research to create a highly sensitive method for measuring soluble immune checkpoint molecules in the blood that placed a small burden on patients and allowed the immune status to be determined simply.
The two parties have developed fully automated method for measuring soluble immune checkpoint molecules that uses the HI-1000, an automated, highly sensitive immunoassay system for research applications. This measurement method uses chemiluminescence enzyme immunoassay (CLEIA) as its measurement principle. Fully automating the measurement method allows the measurement of soluble immune checkpoint molecules to be conducted in 17 minutes (100 tests/hour) and achieves high levels of sensitivity and reproducibility.4
In September 2019, Sysmex began providing assay services for research using this measurement method.
As the measurement method can be used in cancer immunotherapy and as a new method for diagnosing autoimmune diseases, and has the potential to help realize personalized medicine, the two parties will promote R&D with a view toward commercialization, contributing to advances in healthcare.