title: Impact of tumor-specific targeting and dosing schedule on tumor growth inhibition after intravenous administration of siRNA-containing nanoparticles.
abstract: This study addresses issues of relevance for siRNA nanoparticle delivery by investigating the functional impact of tumor-specific targeting and dosing schedule. The investigations are performed using an experimental system involving a syngeneic mouse cancer model and a theoretical system based on our previously described mathematical model of siRNA delivery and function. A/J mice bearing subcutaneous Neuro2A tumors approximately 100 mm(3) in size were treated by intravenous injection with siRNA-containing nanoparticles formed with cyclodextrin-containing polycations (CDP). Three consecutive daily doses of transferrin (Tf)-targeted nanoparticles carrying 2.5 mg/kg of two different siRNA sequences targeting ribonucleotide reductase subunit M2 (RRM2) slowed tumor growth, whereas non-targeted nanoparticles were significantly less effective when given at the same dose. Furthermore, administration of the three doses on consecutive days or every 3 days did not lead to statistically significant differences in tumor growth delay. Mathematical model calculations of siRNA-mediated target protein knockdown and tumor growth inhibition are used to elucidate possible mechanisms to explain the observed effects and to provide guidelines for designing more effective siRNA-based treatment regimens regardless of delivery methodology and tumor type.
authors.affiliation: Chemical Engineering, California Institute of Technology, 1200 E. California Blvd., MC 210-41, Pasadena, California 91125, USA.
authors.forename: Derek W
authors.initials: DW
authors.lastname: Bartlett
authors.forename: Mark E
authors.initials: ME
authors.lastname: Davis
mesh_terms: D000818:Animals; D049109:Cell Proliferation; D004305:Dose-Response Relationship, Drug; D005260:Female; D018390:Gene Targeting / Q000379:methods*; D015316:Genetic Therapy / Q000379:methods*; D007275:Injections, Intravenous; D051379:Mice; D053758:Nanoparticles / Q000008:administration & dosage*; D009447:Neuroblastoma / Q000235:genetics* / Q000473:pathology / Q000628:therapy*; D034741:RNA, Small Interfering / Q000008:administration & dosage*; D014168:Transferrin / Q000235:genetics*
chemical_list: D034741:RNA, Small Interfering; D014168:Transferrin