Commensal Bacteria Control Cancer Response to Therapy by Modulating the Tumor Microenvironment

The Microbiota Makes for Good Therapy The gut microbiota has been implicated in the development of some cancers, such as colorectal cancer, but—given the important role our intestinal habitants play in metabolism—they may also modulate the efficacy of certain cancer therapeutics. Iida et al. (p. 967 ) evaluated the impact of the microbiota on the efficacy of an immunotherapy [CpG (the cytosine, guanosine, phosphodiester link) oligonucleotides] and oxaliplatin, a platinum compound used as a chemotherapeutic. Both therapies were reduced in efficacy in tumor-bearing mice that lacked microbiota, with the microbiota important for activating the innate immune response against the tumors. Viaud et al. (p. 971 ) found a similar effect of the microbiota on tumor-bearing mice treated with cyclophosphamide, but in this case it appeared that the microbiota promoted an adaptive immune response against the tumors.