Purpose: The microbiota is recognized as an important contributor to the efficacy of immunotherapies. The aim of this study is to analyze the role of gut microbiota and related metabolites in the response of chimeric antigen receptor (CAR) T cells for non-Hodgkin lymphoma. Experimental Design: Stool, serum, and clinical data were collected from 84 patients with non-Hodgkin lymphoma from four hospitals before CD19 CAR T-cell treatment. The microbiota was characterized through 16S rRNA gene sequencing, and serum short-chain fatty acids (SCFA) were measured using mass spectrometry. CAR T cells were exposed to butyrate; their in vitro cytotoxicity was determined, and molecular mechanisms were characterized by flow cytometry and RNA sequencing and then assessed in an in vivo model. Results: As 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, and Butyricicoccus, as having a relatively higher abundance in the microbiota of patients who responded to CAR T cells. 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-cell 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.

CRISPR is becoming an indispensable tool in biological research, revolutionizing diverse fields of medical research and biotechnology. In the last few years, several CRISPR-based genome-targeting tools have been translated for the study of hematological neoplasms. However, there is a lack of reviews focused on the wide uses of this technology in hematology. Therefore, in this review, we summarize the main CRISPR-based approaches of high throughput screenings applied to this field. Here we explain several libraries and algorithms for analysis of CRISPR screens used in hematology, accompanied by the most relevant databases. Moreover, we focus on (1) the identification of novel modulator genes of drug resistance and efficacy, which could anticipate relapses in patients and (2) new therapeutic targets and synthetic lethal interactions. We also discuss the approaches to uncover novel biomarkers of malignant transformations and immune evasion mechanisms. We explain the current literature in the most common lymphoid and myeloid neoplasms using this tool. Then, we conclude with future directions, highlighting the importance of further gene candidate validation and the integration and harmonization of the data from CRISPR screening approaches.