Nanoparticle‐Bound Cytolytic Peptide Prodrugs for Cancer Therapy

Abstract

ObjectiveTo develop a nanoparticle platform which promotes the delivery of cytolytic peptide prodrugs to tumors and their activation by locally produced proteases.Introduction: Melittin is a peptide toxin derived from bee venom which has been proposed as a cancer therapy due to its cytolytic activity. Yet, its therapeutic applications have been limited by its nonspecific cytotoxicity and rapid clearance from the circulation. We have previously developed a prodrug form of melittin which is activated upon cleavage by matrix metalloproteinase 9 (MMP‐9), a protease closely linked with tumor growth and metastasis. Here, we present a platform for delivery of this prodrug based on a perfluorocarbon nanoparticle system designed to enhance intratumoral accumulation while permitting prodrug activation by local MMP‐9 activity.Methods and Results: Incubation of the melittin prodrug with perfluorocarbon nanoparticles (NPs) resulted in stable loading of 10,250 peptides per NP with no significant change in NP size. Addition of 20 nM MMP‐9 led to activation of 57.8% of NP‐bound prodrug within 3 hours. B16F10 melanoma cell viability was virtually eliminated following incubation with 50 μM free or NP‐bound prodrug in the presence of MMP‐9 (p < 0.001 compared to control). In a mouse model of B16F10 lung metastasis, NP accumulation in lung tumors was demonstrated by both fluorescence microscopy (Figure A; NPs in red) and quantitative 19F magnetic resonance spectroscopy (Figure B). Gelatin zymography confirmed production of active MMP‐9 by these tumors.ConclusionPerfluorocarbon nanoparticles accumulate within tumors and permit activation of bound prodrugs, making them promising delivery vehicles for cytolytic peptide agents.Research Support: NIH R01 HL073646 image image