A study analyzing patients with acute lymphoblastic leukemia (ALL) and non-Hodgkin lymphoma (NHL) treated with CD19 CAR T cells found that a high abundance of obligate anaerobes such as Ruminococcus, Bacteroides, Faecalibacterium, and Akkermansia was associated with a complete response at day 100 [253]. Here, CD19 is linked to non-Hodgkin lymphoma.