Solid tumor starts in a specific organ, grow, and then metastasize. Most cancers, such as stomach, lung, colorectal, and breast cancer, fall into this category. In the case of solid cancer, surgery is performed when possible, and if not, chemotherapy (treatment using chemicals with anticancer effects) is prescribed for the palliative purpose of prolonging survival because it is difficult to have a complete cure.

Currently, research on immunotherapy is actively underway, is effective in various cancers.Since many IO therapy such as Keytruda have been developed in the recent 2-3 years, IO research has been getting considerable attention as a treatment option.

Cancers have an environment different from the surrounding tissue that of normal cells due to their genetic or metabolic peculiarities. This environment is called the tumor microenvironment, and this tumor-specific environment is one of the factors that drive resistance or refractory to chemical, radioactive, or immune anti-cancer therapies. When the concentration of adenosine is high in the tumor microenvironment, the cancer-killing ability of immune cells is severely compromised. Controlling this tumor-specific microenvironment, the effect of immune checkpoint inhibitors could be enhanced, providing a solution to unmet needs of refractory and resistance of immunotherapeutic agents.