Bacterial biomarker

A method for identifying and treating a subject that will respond to therapy with an immune checkpoint inhibitor comprising determining the abundance of bacteria from at least 9 different species in a biological sample from said subject that comprises gut flora wherein said bacteria comprise a 16S rDNA sequence selected from SEQ ID NOs:

• 1 to 15 or a sequence having at least 98.7% sequence identity with a nucleic acid sequence selected from SEQ ID NOs:
• 1 to 15 wherein said abundance is indicative of a response of a subject to therapy with an anti-PD-1 antibody or an anti-PD-L1 antibody;
• and
• administering to the subject an immune checkpoint inhibitor therapy if the subject is identified as a subject that will respond to therapy with an anti-PD-1 antibody or an anti-PD-L1 antibody, thereby treating the subject;
• wherein the subject is a cancer patient and the cancer is selected from melanoma, urothelial cancer, breast cancer, non-small cell lung cancer, lymphoma, renal cancer, colorectal cancer, cancer of the esophagus, cancer of the head and neck or gastric cancer.