Intrinsic PD-L1 Degradation Induced by a Novel Self-Assembling Hexapeptide for Enhanced Cancer Immunotherapy
Hongxia Zhang1, Ming Ji1, Yamei Wang2
1The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, Tianjin Key Laboratory on Technologies Enabling Development of Clinical Therapeutics and Diagnostics, School of Pharmacy, Tianjin Medical University, Tianjin, 300070, China.
Abstract:
Programmed death-ligand 1 (PD-L1) is a critical immune checkpoint protein that facilitates tumor immune evasion. While antibody-based PD-1/PD-L1 inhibitors have shown promise, their limitations necessitate the development of alternative therapeutic strategies. This work addresses these challenges by developing a hexapeptide, KFM (Lys-Phe-Met-Phe-Met-Lys), capable of both directly downregulating PD-L1 and self-assembling into a ROS-responsive supramolecular hydrogel. This dual functionality allows Gel KFM to function as a localized drug delivery system and a PD-L1 inhibitor. Loading the hydrogel with mitoxantrone (MTX) and metformin (MET) further enhances the therapeutic effect by combining chemotherapy with PD-L1 downregulation. In vitro and in vivo studies demonstrate significant tumor growth inhibition, increased CD8+ T cell infiltration, and reduced intratumoral PD-L1 expression following peritumoral administration. Mechanistically, KFM promotes PD-L1 degradation via a ubiquitin-dependent pathway. This "carrier-free" delivery system expands the role of supramolecular hydrogels beyond passive carriers to active immunotherapeutic agents, offering a promising new strategy for cancer therapy.
Insights
A novel hexapeptide hydrogel, Gel KFM, effectively inhibits tumor growth by downregulating programmed death-ligand 1 (PD-L1) and delivering chemotherapy. This innovative approach enhances anti-tumor immunity and offers a promising cancer therapy strategy.
Area of Science:
- Biotechnology
- Immunotherapy
- Materials Science
Background:
- Programmed death-ligand 1 (PD-L1) is a key protein enabling tumors to evade immune responses.
- Current antibody-based inhibitors for PD-1/PD-L1 have limitations, driving the need for new therapeutic methods.
Purpose of the Study:
- To develop a novel hexapeptide (KFM) that downregulates PD-L1 and self-assembles into a ROS-responsive supramolecular hydrogel.
- To create a dual-function hydrogel system for localized drug delivery and PD-L1 inhibition.
- To enhance therapeutic efficacy by combining chemotherapy with PD-L1 downregulation.
Main Methods:
- Synthesized a hexapeptide (Lys-Phe-Met-Phe-Met-Lys) and formulated it into a ROS-responsive supramolecular hydrogel (Gel KFM).
- Loaded Gel KFM with mitoxantrone (MTX) and metformin (MET) for combined chemo-immunotherapy.
- Evaluated in vitro and in vivo efficacy, including tumor growth inhibition, CD8+ T cell infiltration, and PD-L1 expression levels.
- Investigated the mechanism of PD-L1 downregulation via a ubiquitin-dependent pathway.
Main Results:
- Gel KFM demonstrated dual functionality as a localized drug delivery system and a PD-L1 inhibitor.
- Peritumoral administration of Gel KFM (with MTX and MET) significantly inhibited tumor growth in vivo.
- Enhanced CD8+ T cell infiltration and reduced intratumoral PD-L1 expression were observed.
- KFM was found to promote PD-L1 degradation through a ubiquitin-dependent mechanism.
Conclusions:
- This carrier-free delivery system transforms supramolecular hydrogels into active immunotherapeutic agents.
- Gel KFM represents a promising new strategy for cancer therapy by combining chemotherapy with targeted PD-L1 downregulation.
- The study highlights the potential of self-assembling peptides in developing advanced cancer treatments.
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