Manipulating the Click Reactivity of Dibenzoazacyclooctynes: From Azide Click Component to Caged Acylation Reagent by Silver Catalysis.

Strain-promoted azide-alkyne cycloaddition using dibenzoazacyclooctyne (DBCO) is widely applied in copper-free bioorthogonal reactions. Reported here is the efficient acid-promoted rearrangement and silver-catalyzed amidation of DBCO, which alters its click reactivity robustly. In the switched click reaction, DBCO, as a caged acylation reagent, enables rapid peptide/protein modification after decaging facilitated by silver catalysts, rendering site-specific conjugation of an IgG antibody by a Fc-targeting peptide.

Design and synthesis of novel dual-cyclic RGD peptides for αvß3 integrin targeting.

The specific binding of RGD cyclic peptide with integrin αvß3 attracts great research interest for tumor-targeting drug delivery. Herein, we designed and synthesized a series of dual-ring RGD-peptide derivatives as a drug carrier for αvß3 targeting. Three novel peptides showed excellent cell adhesion inhibition effect, in which, P3 exhibited 7-fold enhancement in IC50 compared with cyclo(RGDfK). Drug-loaded cytotoxicity experiment and imaging experiment indicated that such dual-cyclic RGD peptides have good tumor targeting effects. This work provides a new strategy for the design of novel RGD peptides.

Carbohydrate Strengthens the Immunotherapeutic Effect of Small-Molecule PD-L1 Inhibitors.

PD-1/PD-L1 checkpoint blockade has demonstrated great success in cancer immunotherapy. Small-molecule PD-L1 inhibitors also attract significant research interests but remain challenging in the efficacy and safety. Carbohydrate moiety and carbohydrate-binding proteins (lectins) play important roles in immune modulation including antigen recognition and presenting. Herein, we reported a novel strategy to strengthen the immunotherapeutic effect of small-molecule PD-L1 inhibitors by introducing sugar motifs, which may utilize the carbohydrate-mediated immune enhancement for cancer treatment. The data revealed that glycoside compounds containing mannose or N-acetylglucosamine exhibited the best results in IFN-γ secretion. Moreover, compared to the nonglycosylated compounds, glycosides C3 and C15 demonstrated significant lower cytotoxicity and effective in vivo antitumor potency in the CT26 and melanoma B16-F10 tumor models with good tolerance. Notably, tumor-infiltrating lymphocyte (TIL) analysis validated increased CD3+, CD4+, CD8+, and granzyme B+ T cells after glycoside treatments. This work presents a new concept to improve the immunotherapy.