Postbiotika-vermittelte metabolische Modulation von CAR-T-Zellen zur Optimierung der Krebsimmuntherapie

Adoptive immunotherapy using chimeric antigen receptor (CAR) T cells has revolutionized the treatment of hematological malignancies. Despite huge clinical successes for cancer entities such as multiple myeloma and lymphoma, treatment of solid tumors remains challenging. Factors in the tumor microenvironment (TME) lead to improper functioning of CAR T cells. Recently, the human microbiome and its metabolites have been associated with the outcome of cellular therapies. Here, the abundance of the short-chain fatty acid (SCFA) pentanoate has been identified as a predictive marker for the outcome of CAR T cell therapy. To study the effect of pentanoate on cellular immunotherapy, we performed in-depth investigation of CAR T cells generated in the presence of pentanoate both in vitro and in vivo. Our data demonstrate that a one-time treatment with pentanoate at the beginning of the manufacturing process of murine CAR T cells leads to enhanced transduction efficiency without compromising viability. This was accompanied by a pronounced shift in functionality in regard to lytic activity and cytokine secretion upon antigen-encounter. This enhancement in functionality of pentanoate-treated CAR T cells was confirmed in two different solid tumor models and under TME mimicking conditions in vitro. Mechanistically, we demonstrated that pentanoate acts both as an HDAC class I inhibitor as well as a modulator of T cell metabolism. Comparing clinically available substances able to affect only one of the two modes of action highlighted the dual functionality of pentanoate. Metabolic tracing of isotope-labeled pentanoate revealed its incorporation in the TCA cycle via the acetyl- and succinyl-CoA entry points. Inhibition of the ATP-citrate-lyase, which links the metabolic output and histone acetylation, led to an accumulation of pentanoate-derived citrate from the succinyl-CoA route and decreased functionality of engineered T cells providing evidence of pentanoate’s unique modulatory function. Finally, these insights facilitated the establishment of an optimized manufacturing protocol to confer similar features to human CAR T cells. In summary, we show that pentanoate is a unique modulator of CAR T cells and its integration into the engineering process results in a distinct phenotypic shift granting superior functionality both in vitro and in vivo. Hereby, we introduce a novel perspective, emphasizing the critical connection between microbiome-derived metabolites and cancer immunotherapy that can be used for the improvement of T cell engineering.