Definition

A hydrogel carrier-based, sustained intra-tumoral release formulation of resiquimod, a Toll-like receptor (TLR) 7/8 agonist and an imidazoquinolinamine, with potential immunostimulating and antineoplastic activities. Upon intra-tumoral administration, resiquimod binds to TLR7 and 8, which are found mainly on dendritic cells (DCs), macrophages, and B lymphocytes, and activates the TLR signaling pathway, which results in the induction of the nuclear translocation of transcription activator nuclear factor kappa-B (NF-kB) and activation of other transcription factors. Subsequently, NF-kB-dependent gene expression is induced and cytokine production increases, especially interferon-alpha (INF-a), which results in the enhancement of T-helper 1 (Th1) immune responses. Activation of DCs also results in the activation of cytotoxic T-lymphocyte (CTL) and B-lymphocyte immune responses. This may cause tumor cell lysis. TLR7 and 8, members of the TLR family, play fundamental roles in the activation of the immune system.