Tetrandrine alleviates macrophage activation syndrome after CAR-T cell therapy

Cytokine release syndrome (CRS) and secondary hemophagocytic lymphohistiocytosis (sHLH) are severe and potentially life-threatening complications after chimeric antigen receptor T (CAR-T) cell therapy, driven by excessive cytokine release from macrophages. The traditional Chinese herbal remedy d-tetrandrine (tetrandrine) exhibits anti-inflammatory properties in various diseases; however, its efficacy in mitigating CRS and sHLH remains underexplored.

To establish an in vitro CRS model, supernatants from co-cultures of CAR-T and Raji cells were used to stimulate mTHP-1 macrophages. To model CRS and lymphoma in vivo, CAR-T and Raji cells were infused into the tail vein of NCG mice. An sHLH model was established in C57BL/6 J mice through intraperitoneal administration of Poly I:C and LPS.

Results demonstrated that tetrandrine markedly reduced the secretion of IL-6 and IL-1β from macrophages, alone with IL-2, TNF-α, GM-CSF, IL-8, and IFN-γ from CAR-T cells, while preserving the cytotoxic functions exhibited by CAR-T cells. In mouse models, tetrandrine treatment effectively decreased the concentrations of mouse IL-6 and human IFN-γ in mice serum, while maintaining the therapeutic efficacy exhibited by CAR-T cells. Mechanistically, tetrandrine enhances autophagy through the restraint of the AKT/mTOR signaling pathway, which is dysregulated in macrophages during CRS. Notably, lysosomal injury observed in macrophages during CRS was ameliorated by tetrandrine, which restored lysosomal pH and increased lysosome numbers, thereby positively influencing autophagy. In the sHLH model, tetrandrine treatment extended survival and alleviated pathological features, highlighting its protective role in mitigating the adverse effects of CRS and sHLH.

This study identified tetrandrine as a promising therapeutic candidate for attenuating macrophage activation associated with CAR-T cell therapy and LPS/Poly I:C-induced stimulation. These findings underscore the potential of tetrandrine to mitigate toxicities after CAR-T cell therapy while ensuring its therapeutic efficacy.