A Novel Engineering Cell Therapy Platform Mimicking the Immune Thrombocytopenia‐Derived Platelets to Inhibit Cytokine Storm in Hemophagocytic Lymphohistiocytosis

Abstract

Hemophagocytic lymphohistiocytosis (HLH) is a common and highly fatal hyperinflammatory syndrome characterized by the aberrant activation of macrophages. To date, there is a lack of targeted therapies for HLH. It is validated that macrophages in HLH efficiently phagocytose anti‐CD41‐platelets (anti‐CD41‐PLTs) from immune thrombocytopenia (ITP) patients in previous research. Hence, the pathological mechanisms of ITP are mimicked and anti‐CD41‐PLTs are utilized to load the macrophage‐toxic drug VP16 to construct macrophage‐targetable engineered platelets anti‐CD41‐PLT‐VP16, which is a novel targeted therapy against HLH. Both in vitro and in vivo studies demonstrate that anti‐CD41‐PLT‐VP16 has excellent targeting and pro‐macrophage apoptotic effects. In HLH model mice, anti‐CD41‐PLT‐VP16 prevents hemophagocytosis and inhibits the cytokine storm. Mechanistic studies reveal that anti‐CD41‐PLT‐VP16 increases the cytotoxicity of VP16, facilitating precise intervention in macrophages. Furthermore, it operates as a strategic “besieger” in diminishing hyperinflammation syndrome, which can indirectly prevent the abnormal activation of T cells and NK cells and reduce the Ab‐dependent cell‐mediated cytotoxicity effect. The first platelet‐based clinical trial is ongoing. The results show that after treatment with anti‐CD41‐PLT‐VP16, HLH patients have a threefold increase in the overall response rate compared to patients receiving conventional chemotherapy. In conclusion, anti‐CD41‐PLT‐VP16 provides a general insight into hyperinflammation syndrome and offers a novel clinical therapeutic strategy for HLH.