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. The FDA-approved BCG for non-muscle invasive bladder cancer is a highly related strategy of Coley's Toxin.