Intravesical Delivery of Small Activating RNA Formulated into Lipid Nanoparticles Inhibits Orthotopic Bladder Tumor Growth

Moo Rim Kang,Long-Cheng Li,Glen Yang,Hila Epstein-Barash,Robert F Place,Klaus Charisse,Muthiah Manoharan

doi:10.1158/0008-5472.can-12-1871

Moo Rim Kang, Long-Cheng Li + Show 5 more

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https://doi.org/10.1158/0008-5472.can-12-1871

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Abstract

Practical methods for enhancing protein production in vivo remain a challenge. RNA activation (RNAa) is emerging as one potential solution by using double-stranded RNA (dsRNA) to increase endogenous gene expression. This approach, although related to RNA interference (RNAi), facilitates a response opposite to gene silencing. Duplex dsP21-322 and its chemically modified variants are examples of RNAa-based drugs that inhibit cancer cell growth by inducing expression of tumor suppressor p21(WAF1/CIP1) (p21). In this study, we investigate the therapeutic potential of dsP21-322 in an orthotopic model of bladder cancer by formulating a 2'-fluoro-modified derivative (dsP21-322-2'F) into lipid nanoparticles (LNP) for intravesical delivery. LNP composition is based upon clinically relevant formulations used in RNAi-based therapies consisting of PEG-stabilized unilamellar liposomes built with lipid DLin-KC2-DMA. We confirm p21 induction, cell-cycle arrest, and apoptosis in vitro following treatment with LNP-formulated dsP21-322-2'F (LNP-dsP21-322-2'F) or one of its nonformulated variants. Both 2'-fluoro modification and LNP formulation also improve duplex stability in urine. Intravesical delivery of LNP-dsP21-322-2'F into mouse bladder results in urothelium uptake and extends survival of mice with established orthotopic human bladder cancer. LNP-dsP21-322-2'F treatment also facilitates p21 activation in vivo leading to regression/disappearance of tumors in 40% of the treated mice. Our results provide preclinical proof-of-concept for a novel method to treat bladder cancer by intravesical administration of LNP-formulated RNA duplexes.

Highlights

Bladder cancer is the fifth most common human malignancy [1]
lipid nanoparticles (LNP)-dsP21322-20F mirrored nonformulated transfection results (Fig. 3D). These results indicate that treatment with LNPdsP21-322-20F or its nonformulated variants promote apoptosis contributing to the antitumor activity in bladder cancer cells
We previously showed that dsP21-322 possesses in vitro antigrowth activity in T24 and J82 bladder cancer cell lines [27]

Summary

Introduction

Bladder cancer is the fifth most common human malignancy [1]. 70% of bladder cancer incidences are diagnosed at a superficial stage in which about half will recur following transurethral resection (TUR) despite post-op therapy. Intravesical administration of chemical and/or immunologic agents (e.g., mitomycin, Bacillus Calmette-Guerin, etc.) is often used to eradicate residual tumor cells; such treatments can have limited efficacy and adverse side effects [2]. As many as 10% to 30% of recurrent tumors will progress to a higher grade and stage inevitably forming locally invasive cancer [3, 4]. Authors' Affiliations: 1Department of Urology and Helen Diller Comprehensive Cancer Center, University of California; 2RNA Therapeutics Inc., San Francisco, California; and 3Alnylam Pharmaceuticals, Inc., Cambridge, Massachusetts. Note: Supplementary data for this article are available at Cancer Research Online (http://cancerres.aacrjournals.org/).

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