Targeted delivery of TLR3 agonist to tumor cells with single chain antibody fragment-conjugated nanoparticles induces type I-interferon response and apoptosis

Abstract

Application of Toll-like receptor (TLR) agonists is a promising approach to treat cancer. In particular, nucleic acid-based TLR agonists such as short ssRNA and dsRNA molecules, which activate endosomal TLRs, can be delivered to tumors by use of nanoparticle delivery systems. However, such delivery systems bear unspecific side effects and poor pharmacokinetics. To overcome these limitations we developed a system for targeted delivery of a 50 bp dsRNA TLR3 agonist (Riboxxol) to treat PSCA-positive tumor cells, which consists of neutravidin conjugated to mono-biotinylated dsRNA and to humanized mono-biotinylated anti-PSCA single chain antibody derivative scFv(h-AM1)-BAP. The assembly of the components resulted in the formation of nanoparticle-like immunoconjugates designated Rapid Inducer of Cellular Inflammation and Apoptosis (RICIA). Anti-PSCA-RICIA exclusively delivered Riboxxol to PSCA-positive tumor cells as well as subcutaneous tumors. Uptake of anti-PSCA-RICIA induced a type I-interferon response and apoptosis in HEK-Blue hTLR3/PSCA reporter cells and PSCA-positive HT1376 bladder cancer cells in vitro . No such effects were observed when using RICIA coupled to an unspecific control antibody or when using Riboxxol alone. Treatment of HT1376 xenografts in immune-deficient hosts with targeted delivery of TLR3 agonist did not induce adverse effects and only modestly inhibited tumor growth when compared to controls. These results suggest promising activation of innate immune response and apoptosis upon selective delivery of TLR3 agonists in tumor cells. Yet, further studies using syngeneic and orthotopic tumor models are needed to fully exploit the potential of RICIA immunoconjugates.

A Novel Model of Cancer Drug Resistance: Oncosomal Release of Cytotoxic and Antibody-Based Drugs

“…Indeed, macrophage-derived exosome-encapsulated paclitaxel was developed to overcome MDR in cancer cells [192]. Targeted delivery of a TLR3 agonist with single-chain antibody fragment-conjugated nanoparticles induced a type I-interferon response and apoptosis in tumor cells [193]. As these are interesting but complex aspects of the topic, we will discuss them more extensively in the future.…”

Exosome Release of Drugs: Coupling with Epithelial-Mesenchymal Transition

“…Indeed, macrophage-derived exosome-encapsulated paclitaxel was developed to overcome multidrug resistance (MDR) in cancer cells [104]. Targeted delivery of a TLR3 agonist with singlechain antibody fragment-conjugated nanoparticles induced a type I-interferon response and apoptosis in tumor cells [105].…”

RIPK1‐mediated immunogenic cell death promotes anti‐tumour immunity against soft‐tissue sarcoma

“…To test this principle, we activated Ripk1‐induced cell death in the three drug‐tolerant tumour lines (124, 133 and 136) using Riboxxol. Riboxxol is a synthetic TLR3 agonist that triggers Ripk1 activation (Lucifora et al , ; Schau et al , ) and that is well tolerated when administered systemically or via intra‐tumour injections. We found that in combination with SM, Riboxxol potently killed all three drug‐tolerant tumour lines (Fig F).…”