Adoptive immunotherapy combined with intratumoral TLR agonist delivery eradicates established melanoma in mice

Abstract

Toll-like receptor (TLR) agonists can trigger broad inflammatory responses that elicit rapid innate immunity and promote the activities of lymphocytes, which can potentially enhance adoptive immunotherapy in the tumor-bearing setting. In the present study, we found that Polyinosinic:Polycytidylic Acid [Poly(I:C)] and CpG oligodeoxynucleotide 1826 [CpG], agonists for TLR 3 and 9, respectively, potently activated adoptively transferred T cells against a murine model of established melanoma. Intratumoral injection of Poly(I:C) and CpG, combined with systemic transfer of activated pmel-1 T cells, specific for gp10025–33, led to enhanced survival and eradication of 9-day established subcutaneous B16F10 melanomas in a proportion of mice. A series of survival studies in knockout mice supported a key mechanistic pathway, whereby TLR agonists acted via host cells to enhance IFN-γ production by adoptively transferred T cells. IFN-γ, in turn, enhanced the immunogenicity of the B16F10 melanoma line, leading to increased killing by adoptively transferred T cells. Thus, this combination approach counteracted tumor escape from immunotherapy via downregulation of immunogenicity. In conclusion, TLR agonists may represent advanced adjuvants within the setting of adoptive T-cell immunotherapy of cancer and hold promise as a safe means of enhancing this approach within the clinic.

Increased Numbers of Monocyte-Derived Dendritic Cells during Successful Tumor Immunotherapy with Immune-Activating Agents

“…Yet, relatively little research has examined the effects of immunostimulatory treatments on DCs in tumors and tumor-draining LNs. CpG oligodeoxynucleotides were shown to enhance IL-12 production in tumoral DCs (32), and, together with poly I:C, they can induce the activation of DCs in dLNs (33); however, the impact of this and other treatments on DC activation, migration to dLNs, Ag presentation, and the responding DC subsets has not been determined. In our experiments, DC numbers and activation status in dLNs did not correlate with increased T cell proliferation or the antitumor effect.…”

NF-κB activation during intradermal DNA vaccination is essential for eliciting tumor protective antigen-specific CTL responses

“…Poly(I:C) and CpG were shown to be responsible for upregulation of CD40 and CD86 on pDCs enriched from tumor draining lymph nodes. 31 In the context of vaccination, it has been found that intratumoral injection of TLR3/9 ligands was responsible for reprograming the infiltrating immune cell population; significantly increasing the CD8 to Treg cell ratio and anti-tumor effects of the vaccine strategy. 32 In addition to type I IFNs, proinflammatory cytokines produced after DNA stimulation play a direct role in promoting DC maturation and T cell induction.…”

“…30 Indeed, a different situation can be observed within the tumor microenvironment, where activation of type I IFN-producing PRRs has been shown to promote potent anti-tumor effects by acting on antigen-presenting cells and subsequently on tumor-specific T cells. 31,32 Treatment of B16F10 melanoma tumors with poly(I:C) and CpG oligos, triggering TLR3 and 9 respectively, protected mice from tumor challenge together with melanoma specific T-cell transfer. Poly(I:C) and CpG were shown to be responsible for upregulation of CD40 and CD86 on pDCs enriched from tumor draining lymph nodes.…”

Chemocentric Chemoimmunotherapy: A New Concept in Melanoma Immunotherapy

“…The success of adoptive cell transfer depends on the specificity of T cells for the tumor and their ability to survive and proliferate in the environment. Notably, intratumoral injection of toll-like receptor agonists were found to enhance the potency of activated adoptive cell transfer against a murine model with established subcutaneous melanoma tumors, acting to enhance IFN-production and subsequent killing of the now more immunogenic tumor cells by adoptively transferred T cells (Amos et al, 2011). Metastatic melanoma patients have benefited in certain settings with adoptive cell transfer of tumorinfiltrating lymphocytes in combination with chemotherapeutic lymphodepletion, with an impressive objective response rate of 50-70% (Dudley & Rosenberg, 2007;Gattinoni et al, 2006;Hershkovitz et al, 2010;Khattar et al, 2009;Rosenberg et al, 2008Rosenberg et al, , 2011Rosenberg & Dudley, 2009).…”