Coley's toxins (also called Coley's toxin, Coley's vaccine, Coley vaccine, Coley's fluid or mixed bacterial vaccine) is a mixture containing toxins filtered from killed bacteria of species Streptococcus pyogenes and Serratia marcescens, named after William Coley, a surgical oncologist at the Hospital for Special Surgery who developed the mixture in the late 19th century as a treatment for cancer. Their use in the late nineteenth and early 20th centuries represented a precursor to modern immunotherapy, although at that time their mechanism of action was not completely understood. Many important aspects of the mechanisms of action, such as that involving T-cells and NK cells, have been more recently identified. The FDA-approved BCG for non-muscle invasive bladder cancer is a highly related strategy of Coley's Toxin. History Bacterial immunotherapy for the treatment of cancer has been utilized throughout history, with the earliest cases going back to c 2600 BC. Egyptian physician Imhotep treated tumors by a poultice, followed by incision, to facilitate the development of infection in the desired location and cause regression of the tumors. In 13th century, St. Peregrine experienced spontaneous regression of tumor, after the tumor became infected. In the 18th and 19th centuries, deliberate infection of tumors was a standard treatment, whereby surgical wounds were left open to facilitate the development of infection. Throughout the time period, physicians reported successful treatment of cancer by exposing the tumor to infection including the report of French physician Dussosoy who covered an ulcerated breast carcinoma with gangrenous discharge soaked cloth, resulting in disappearance of tumor. Observations of a relationship between infection and cancer regression date back to at least the 18th century. More specifically, observations of an apparent relationship between erysipelas and remission of cancer predate Coley. For example, Anton Chekhov, in his capacity as a physician, recorded such a relationship in 1884. Coley started his investigations after the death of one of his first patients, Elizabeth Dashiell, from sarcoma. Dashiell was a close childhood friend of John D. Rockefeller, Jr., who later indicated that her death was what first motivated his subsequent funding of cancer research. Frustrated by this case, Coley's subsequent research led him to announce evidence of the apparent relationship between infection and cancer regression, which he published in 1891. His initial attempts at deliberate infection were mixed, but in 1893 he began combining Streptococcus pyogenes and Serratia marcescens, based upon research from G.H. Roger indicating that this