Reprogramming tumor microenvironment via systemic delivery of TLR3 agonist and manganese nanoparticle

Area of Science:

• Immunology
• Nanotechnology
• Cancer Therapeutics

Background:

• Toll-like receptor (TLR) agonists are potent immune adjuvants but have limited direct antitumor effects.
• Activating innate immune pathways is crucial for effective cancer immunotherapy.

Purpose of the Study:

• To investigate manganese ions (Mn2+) as potentiators for TLR agonists in cancer immunotherapy.
• To develop a nanoparticle system for systemic codelivery of TLR agonists and Mn2+.
• To evaluate the therapeutic efficacy and immune mechanisms of the developed nanoparticle.

Main Methods:

• Development of a poly(inosinic:cytidylic acid)-Mn2+ coordination lipid nanoparticle (PLCMP) for systemic codelivery.
• Intratumoral and intravenous administration of PLCMP in tumor-bearing mice models.
• Assessment of immune cell activation (TLR and STING pathways), tumor-specific T cell generation, and antitumor efficacy.
• Combination therapy with anti-PD-1 (α-PD-1) and vaccination strategies using PLCMP.

Main Results:

• Mn2+ potentiated TLR agonists, enhancing TLR and STING pathway activation in innate immune cells.
• Intratumoral administration of TLR3 agonist and Mn2+ showed antitumor efficacy.
• Systemic administration of PLCMP demonstrated tumor accumulation, innate immune activation, and tumor-specific T cell generation.
• PLCMP exhibited TLR3- and STING-dependent antitumor efficacy without significant toxicity.
• Combination therapy with α-PD-1 and PLCMP vaccination resulted in long-lasting antitumor effects and robust CD8+ T cell responses.

Conclusions:

• Simultaneous activation of TLR3 and STING pathways using PLCMP is a promising strategy for cancer immunotherapy.
• PLCMP enhances innate and adaptive immune responses against tumors.
• PLCMP holds potential for both direct cancer immunotherapy and as a vaccine adjuvant for cancer prevention and treatment.