Posttranslational remodeling micelle reverses cell-surface and exosomal PD-L1 immunosuppression in tumors resistant...

Area of Science:

• Oncology
• Immunotherapy
• Nanotechnology

Background:

• Resistance to programmed cell death-ligand 1 (PD-L1) antibody therapy is a significant clinical challenge.
• Sustained PD-L1 replenishment on cell surfaces and exosomes contributes to therapy resistance.
• Posttranslational modifications (PTMs) of PD-L1, like palmitoylation, are critical for its stability and distribution.

Purpose of the Study:

• To investigate the role of PD-L1 palmitoylation in therapy resistance.
• To develop a novel therapeutic strategy targeting PD-L1 PTMs and chemotherapy delivery.
• To evaluate the efficacy of a combined approach in overcoming PD-L1 antibody resistance in melanoma.

Main Methods:

• Disruption of PD-L1 palmitoylation using 2-bromopalmitate (2-BP).
• Fabrication of an amphiphilic, tumor microenvironment (TME)-responsive micelle for co-delivery of 2-BP and cisplatin.
• Assessment of the formulation's impact on cell-surface and exosomal PD-L1, immunosuppression, tumor growth, relapse, metastasis, and T cell memory responses in a melanoma model.

Main Results:

• Disruption of palmitoylation by 2-BP effectively reduced both cell-surface and exosomal PD-L1.
• The co-delivery nanoparticle formulation synergistically eliminated PD-L1 and enhanced chemotherapy.
• The treatment significantly suppressed tumor growth, postsurgical relapse, and metastasis while inducing long-lasting T cell memory responses.

Conclusions:

• Targeting PD-L1 palmitoylation combined with chemotherapy via a TME-responsive nanoformulation is a promising strategy against PD-L1 antibody-resistant melanoma.
• This multimodal approach effectively overcomes immunosuppression and establishes long-term anti-tumor immunity.
• The study presents a novel therapeutic paradigm for overcoming resistance in cancer immunotherapy.