Abstract
The human microbiome comprises the collection of microbiota residing on or within human tissues. It is now well-established that microbial composition impacts an individual’s health. In the cancer realm, the vast majority of microbiome studies have been focused either on the gut, or at the site of solid tumors. Few studies have assessed microbial content at the site of hematological malignancies – blood and bone marrow. Here we characterize the circulating metatranscriptome (i.e. the bacterial and viral RNA in circulation) of 411 patients with acute myeloid leukemia (AML). We find that the circulating metatranscriptome in AML differs substantially from that of healthy controls, and high metatranscriptome loads are associated with antibacterial host response. We observe that specific bacterial genera are associated with response to anti-cancer therapy and disease history, and are tied to host gene expression signatures of heme metabolism. Overall, our study represents an inferred landscape of circulating microbial RNA in AML and suggests potential for its use as a biomarker.