SiRNA Nanoparticle Targeting PD-L1 Activates Tumor Immunity and Abrogates Pancreatic Cancer Growth in Humanized Preclinical Model.

Jae Yun Jung,Kyu-Pyo Kim,Myung Ji Kim,Dong-Young Kim,Hyun Jin Ryu,Suhwan Chang,Sang-Yeob Kim,Hyung Jun Ahn,Seung-Hwan Lee,Yeon-Mi Ryu,Eun Young Choi,Eun Ji Lee

doi:10.3390/cells10102734

Abstract

Pancreatic cancer is characterized by late detection, frequent drug resistance, and a highly metastatic nature, leading to poor prognosis. Antibody-based immunotherapy showed limited success for pancreatic cancer, partly owing to the low delivery rate of the drug into the tumor. Herein, we describe a poly(lactic-co-glycolic acid;PLGA)-based siRNA nanoparticle targeting PD-L1 (siPD-L1@PLGA). The siPD-L1@PLGA exhibited efficient knockdown of PD-L1 in cancer cells, without affecting the cell viability up to 6 mg/mL. Further, 99.2% of PDAC cells uptake the nanoparticle and successfully blocked the IFN-gamma-mediated PD-L1 induction. Consistently, the siPD-L1@PLGA sensitized cancer cells to antigen-specific immune cells, as exemplified by Ovalbumin-targeting T cells. To evaluate its efficacy in vivo, we adopted a pancreatic PDX model in humanized mice, generated by grafting CD34+ hematopoeitic stem cells onto NSG mice. The siPD-L1@PLGA significantly suppressed pancreatic tumor growth in this model with upregulated IFN-gamma positive CD8 T cells, leading to more apoptotic tumor cells. Multiplex immunofluorescence analysis exhibited comparable immune cell compositions in control and siPD-L1@PLGA-treated tumors. However, we found higher Granzyme B expression in the siPD-L1@PLGA-treated tumors, suggesting higher activity of NK or cytotoxic T cells. Based on these results, we propose the application of siPD-L1@PLGA as an immunotherapeutic agent for pancreatic cancer.

Highlights

Pancreatic cancer is one of the leading causes of cancer death, mainly owing to the late diagnosis and lack of effective treatment options [1]
Cells did not show increased proliferation of Cytotoxic T Lymphocytes (CTLs) at three different E:T ratios, similar to the untreated control set. These results indicate that inhibition of PD-1/PD-L1 interactions via RNA interference (RNAi) leads to local expansion of tumor-specific CTLs
Our results indicate the clinical potential of siRNA-mediated PD-L1 knockdown, which suppresses pancreatic tumor growth in the humanized preclinical model

Summary

Introduction

Pancreatic cancer is one of the leading causes of cancer death, mainly owing to the late diagnosis and lack of effective treatment options [1]. RNA interference (RNAi) has the ability to suppress oncogenes, tumor suppressor genes, and their regulators [8]. It has emerged as a promising agent for inducing antitumor immunity in vivo because of its unique advantages, such as the high sequence-specificity for target molecules and “druggable” properties [9]. This strategy is advantageous over antibodies or small molecules, as RNAi-based drugs inhibit the target molecules at the post-transcriptional level rather than at the protein level [10]. Strategies based on antibodies or small molecules require significantly larger amounts of drugs, such that the molar ratio of the target molecule to the drug is at least 1:1, and may be ineffective if a compensatory expression of target molecules occurs in tumor cells

Methods

Results

Conclusion