Phase I study of a new radiosensitizer containing hydrogen peroxide and sodium hyaluronate for topical tumor injection: a new enzyme-targeting radiosensitization treatment, Kochi Oxydol-Radiation Therapy for Unresectable Carcinomas, Type II (KORTUC II).

Using a currently employed linear accelerator, our intent was to inactivate peroxidase/catalase in tumor tissue by the application of hydrogen peroxide, which is degraded to produce oxygen, thus re-oxygenizing the tumor tissue. In this way, we can convert radioresistant tumors into radiosensitive ones. On the basis of this strategy, we previously developed a new enzyme-targeting radiosensitization treatment named KORTUC I, which remarkably enhances the radiotherapeutic effect on various types of superficially exposed and locally advanced malignant neoplasms. Based on our clinical experience using KORTUC I, we also developed a new radiosensitizer containing hydrogen peroxide and sodium hyaluronate for injection into various types of tumors that are not superficially exposed (KORTUC II; described herein). KORTUC II was approved by our local ethics committee for advanced skin cancer, including malignant melanoma, bone/soft tissue malignant neoplasms, breast cancer, and metastatic lymph nodes. A maximum of 6 ml of the agent was injected into tumor tissue one to two times per week under ultrasonographic guidance, just prior to each administration of radiation therapy. Eleven patients, including seven with breast cancer, were enrolled in the KORTUC II trial upon fully informed consent. KORTUC II was well tolerated, with a minimum of adverse effects. Nine of the 11 patients showed a complete response (CR), and no severe complications occurred in any of the 11 patients. This new enzyme-targeting radiosensitization treatment may be indicated for various types of locally advanced neoplasms, including soft tissue neoplasms and breast cancers.