The Potential of the Gut Microbiota and Butyrate to Enhance CAR-T Cell Therapy in Non-Hodgkin Lymphoma

Purpose: The microbiota is recognized as an important contributor to the efficacy of immunotherapies. The aim of this study is to analyse the role of gut microbiota, and related metabolites, in the response of CAR-T cells for non-Hodgkin lymphoma (NHL). Experimental Design: Stool, serum, and clinical data were collected from 84 NHL patients from four hospitals before CD19 CAR-T treatment. The microbiota was characterized through 16S rRNA gene sequencing and serum short-chain fatty acids (SCFAs) were measured using mass spectroscopy. CAR-T cells were exposed to butyrate; their in vitro cytotoxicity was determined, and molecular mechanisms were characterized by flow cytometry and RNA-seq, then assessed in an in vivo model. Results: Since we confirmed the negative impact of antibiotics on the response, we delved into the mechanisms involved. We showed that they reduce microbiota diversity, and that their composition correlates with the response. We identified SCFA-producing bacterial groups including Prevotella, Ruminococcus, or Butyricicoccus as having a relatively higher abundance in the microbiota of patients who responded to CAR-T. Analysis of butyrate levels revealed a positive correlation with survival, potentially representing a novel biomarker of response. Finally, we found that stimulation of CAR-T cells with butyrate induced phenotypic and transcriptomic changes associated with enhanced antitumor efficacy. Conclusions: Our results support the relationship between microbiota and CAR-T therapy major outcomes. Analysis of microbiota led to the identification of SCFAs, especially butyrate as a prognostic factor, and also provides the basis for considering them as chemical modifiers of CAR-T cells to improve their efficacy.