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

Abstract

Purpose: KRAS mutations are frequent driver mutations in multiple cancers. KRAS mutations also induce anti-EGFR antibody resistance in adenocarcinoma such as colon cancer. The aim of this study was to overcome anti-EGFR antibody resistance by coupling the antibody to KRAS-specific siRNA. Experimental Design: The anti-EGFR antibody was chemically coupled to siRNA. The resulting complex was tested for antibody binding efficiency, serum stability and ability to deliver siRNA to EGFR-expressing cells. Western blotting, viability, apoptosis, and colony formation assays were performed for efficacy evaluation in vitro. Furthermore, therapeutic activity of the antibody–KRAS-siRNA complexes was examined in in vivo xenograft mouse tumor models. Results: Antibody–siRNA complexes were targeted and internalized via the EGFR receptor. Upon internalization, target gene expression was strongly and specifically repressed, followed by a reduced proliferation and viability, and induced apoptosis of the cells in vitro. Clonogenic growth of mutant KRAS-bearing cells was suppressed by KRAS-siRNA–anti-EGFR antibody complexes. In xenograft mouse models, anti-EGFR antibody–KRAS-siRNA complexes significantly slowed tumor growth in anti-EGFR–resistant cells. Conclusions: The coupling of siRNA against KRAS to anti-EGFR antibodies provides a novel therapy approach for KRAS-mutated EGFR-positive cancer cells in vitro and in vivo. These findings provide an innovative approach for cancer-specific siRNA application and for enhanced therapeutic potential of monoclonal antibody therapy and personalized treatment of cancer entities. Clin Cancer Res; 21(6); 1383–94. ©2015 AACR.

Delivery strategies and potential targets for siRNA in major cancer types

“…Antibodies conjugated to chemotherapeutic small molecules have also shown successful therapeutic results, with TDM-1 serving as a prominent example of this class of antibody conjugate [58]. Recently, an anti-EGFR antibody conjugated to a siRNA targeted to KRAS has shown activity in vitro and in vivo in colon cancer resistant to EGFR inhibitors [59]. …”

Notch1 targeting siRNA delivery nanoparticles for rheumatoid arthritis therapy

“…Although simple changes in siRNA sequence allow inhibition of any mRNA targets in countless diseases, there are critical hurdles in siRNA therapy such as poor stability and lack in target ability [17]. In an attempt to enhance the therapeutic efficacy, incorporation of cationic polymers, liposome, lipids, and others in siRNA delivery has shown improved target ability in various diseases [18][19][20]. In our previous studies, we proposed the nano-sized siRNA complexes containing polymerized siRNA (poly-siRNA) and thiolated glycol chitosan (tGC) polymers that were very stable nanoparticle structure via charge-charge interaction and disulfide bond crosslinking, simultaneously.…”

“…However, the strongly positively charged nanoparticles have induced undesirable cytotoxicity, which greatly limit their therapeutic uses in clinical fields [16]. Furthermore, the positive charges of those nanoparticles also result in non-specific targeting or high accumulation in liver or spleen captured by the reticuloendothelial system (RES) [20].…”

“…The previous study has demonstrated that poly-siRNA exhibit enhanced biocompatibility and formation with synthetic polymers and proteins, due to its increased molecular weight and stronger negative charge [20,22,23]. First, both 5' ends of sense and antisense strands of siRNA were modified with thiol groups to generate poly-siRNA with reducible disulfide links.…”

Targeting the serrated pathway of colorectal cancer with mutation in BRAF

“…Alternatively, tumor-cell targeted nanoparticles were described as carriers for the systemic administration of siRNAs in animal models [180] and human clinical trials [181] and produced a gene-specific inhibition via the expected an RNA interference mechanism [182]. Also, the coupling of KRAS-specific siRNAs to anti-EGFR antibodies has been presented as a promising approach in CRC [183] and could be applied to target RAC1b.…”