Mutant KRAS is a druggable target for pancreatic cancer

Abstract

Pancreatic ductal adenocarcinoma (PDA) represents an unmet therapeutic challenge. PDA is addicted to the activity of the mutated KRAS oncogene which is considered so far an undruggable therapeutic target. We propose an approach to target KRAS effectively in patients using RNA interference. To meet this challenge, we have developed a local prolonged siRNA delivery system (Local Drug EluteR, LODER) shedding siRNA against the mutated KRAS (siG12D LODER). The siG12D LODER was assessed for its structural, release, and delivery properties in vitro and in vivo. The effect of the siG12D LODER on tumor growth was assessed in s.c. and orthotopic mouse models. KRAS silencing effect was further assessed on the KRAS downstream signaling pathway. The LODER-encapsulated siRNA was stable and active in vivo for 155 d. Treatment of PDA cells with siG12D LODER resulted in a significant decrease in KRAS levels, leading to inhibition of proliferation and epithelial-mesenchymal transition. In vivo, siG12D LODER impeded the growth of human pancreatic tumor cells and prolonged mouse survival. We report a reproducible and safe delivery platform based on a miniature biodegradable polymeric matrix, for the controlled and prolonged delivery of siRNA. This technology provides the following advantages: (i) siRNA is protected from degradation; (ii) the siRNA is slowly released locally within the tumor for prolonged periods; and (iii) the siG12D LODER elicits a therapeutic effect, thereby demonstrating that mutated KRAS is indeed a druggable target.targeted therapy | gene therapy P ancreatic cancer is an aggressive disease that develops in a relatively symptom-free manner and in most cases, is already advanced at the time of diagnosis (1). It has one of the highest fatality rates of all cancers and is one of the leading causes of cancer-related deaths in the Western world (1, 2). Pancreatic ductal adenocarcinoma (PDA) is the most common pancreatic neoplasm, responsible for 95% of pancreatic cancer cases (3). Genetic alterations in the KRAS signaling pathway are involved in over 90% of pancreatic cancer cases (4-6). KRAS mutations were shown to be an early event in the development of pancreatic cancer (5,7,8).The most common KRAS mutation of the human pancreas adenocarcinoma is a gain-of-function substitution mutation of glycine at codon 12 to aspartate (G12D) (5, 9-11). Moreover, PDA cancer cell growth was shown to be dependent on the activity of the mutated KRAS (5, 11) and accordingly, silencing KRAS has proven effective in controlling pancreatic cell line proliferation (12). Here, we aimed to harness the advantages of siRNA technology as a therapeutic modality for pancreatic cancer.Parenteral controlled drug delivery systems are used to improve and advance the therapeutic effects of drug treatments by providing optimized local drug concentrations over prolonged periods of time, reduction of side effects, and cost reduction (13). A prominent method of controlling the release rate of a drug in a pharmaceutical dosage is to embed the active ag...

Genetics and biology of pancreatic ductal adenocarcinoma

“…Direct RAS targeting is also using "structure-activity relationships (SARs) by NMR" strategies that search for molecules binding to several weak pockets that can then be bridged together as a means of strengthening interactions and improving specificity (Shuker et al 1996;Sun et al 2014). Beyond this specific program, other more general oncogenic RAS targeting strategies directly inhibit oncogenic KRAS expression with siRNA nanoparticles, which have shown positive results in xenograft models (Zorde Khvalevsky et al 2013;Yuan et al 2014). Current in vivo siRNA delivery methods remain inadequate to target cancer cells (Williford et al 2014), although exosome-based delivery particles may offer improved pharmacology (Wahlgren et al 2012).…”

Antibody-Mediated Delivery of Anti–KRAS-siRNA In Vivo Overcomes Therapy Resistance in Colon Cancer

“…A first in-man study followed this strategy, combining siRNAs against VEGF and KSP in lipid nanoparticles was effective in patients with hepatocarcinoma (9). A recent publication underlines the importance to target KRAS with siRNA: Here, the authors chose to apply KRAS siRNA with the help of miniature polymer capsules locally implanted to xenografted pancreatic tumors (47). All of these therapeutic approaches, especially the local administrations of siRNA would benefit from the possibility of specific targeting to tumor cells to receive systemic effects (48).…”

RNA Therapeutics in Oncology: Advances, Challenges, and Future Directions

“…108 The siRNA siG12D, which is selective for mutant KRAS (KRASG12D mutation), is encapsulated in a biodegradable polymer Local Drug Eluter (LODER) for controlled and prolonged delivery. 109 A phase 1 trial was conducted in patients with locally advanced adenocarcinoma of the pancreas to assess efficacy and local distribution after intratumoral injection of siG12D-LODER by an endoscopic ultrasound needle. This drug has now advanced into a phase 2 study to assess its efficacy in combination with gemcitabine or folfirinox chemotherapy in patients with unresectable locally advanced pancreatic cancer.…”