From Functional Group and Metabolite Analysis to Rational Design: Discovery of BXY-14 as a Highly Potent TLR2 Agonist
Hongbin Jia1, Wei Ma1, Yang Gong2
1State Key Laboratory of Natural Product Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, P.R. China.
Abstract:
TLR2 bridges innate and adaptive immunity, with agonists showing promise in vaccines and cancer therapy. In this study, we found natural product CaLGL-1, which functions as a "quiescent agonist" of TLR2, with its immunostimulatory potential masked by a labile acetal group. In an oxidative environment, CaLGL-1 is converted into potent TLR2 agonist. Inspired by this phenomenon, we rationally designed BXY-14, a derivative exhibiting cross-species TLR2 agonist activity. This compound demonstrates exceptional potency (THP-1 cells, EC50 = 2.2 nM; mBMDCs, EC50 = 1.8 nM), and functions as a superior vaccine adjuvant, eliciting stronger antibody responses than Diprovocim. Additionally, in murine models, BXY-14 markedly downregulated intratumoral PD-L1 expression and demonstrated synergistic efficacy with the anti-PD-L1 monoclonal antibody atezolizumab, resulting in significantly prolonged overall survival. Together, this work establishes metabolically gated immunity and delivers a translational TLR2 agonist bridging bacterial metabolite chemistry with immunotherapy.
Insights
Researchers discovered BXY-14, a potent Toll-like receptor 2 (TLR2) agonist. This compound acts as a superior vaccine adjuvant and enhances cancer immunotherapy by downregulating PD-L1, prolonging survival in mice.
Area of Science:
- Immunology
- Medicinal Chemistry
- Pharmacology
Background:
- Toll-like receptor 2 (TLR2) plays a crucial role in bridging innate and adaptive immunity.
- TLR2 agonists hold significant potential for vaccine development and cancer immunotherapy.
Purpose of the Study:
- To identify and design novel TLR2 agonists with enhanced immunostimulatory properties.
- To evaluate the efficacy of the designed compound as a vaccine adjuvant and in cancer immunotherapy.
Main Methods:
- Identification of natural product CaLGL-1 as a quiescent TLR2 agonist.
- Rational design and synthesis of BXY-14, a potent cross-species TLR2 agonist derivative.
- Assessment of BXY-14's potency in THP-1 cells and murine dendritic cells (mBMDCs).
- Evaluation of BXY-14 as a vaccine adjuvant in comparison to Diprovocim.
- Investigation of BXY-14's efficacy in combination with atezolizumab in murine cancer models.
Main Results:
- CaLGL-1 is converted to a potent TLR2 agonist in oxidative environments.
- BXY-14 exhibits exceptional potency (EC50 = 2.2 nM in THP-1 cells, 1.8 nM in mBMDCs).
- BXY-14 elicits superior antibody responses compared to Diprovocim when used as a vaccine adjuvant.
- BXY-14 significantly downregulates intratumoral PD-L1 expression in murine models.
- Combination therapy with BXY-14 and atezolizumab results in synergistic efficacy and prolonged overall survival.
Conclusions:
- Metabolically gated immunity is established as a novel immunological concept.
- BXY-14 is a potent, translationally relevant TLR2 agonist with dual applications in vaccine adjuvant and cancer immunotherapy.
- This work bridges bacterial metabolite chemistry with immunotherapy, offering new therapeutic strategies.
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