Targeted Delivery Of Temozolomide To Pediatric Brain Tumors Using Micelle-Based Theranostic Nanocarriers

Diffuse intrinsic pontine glioma (DIPG) is the single most devastating pediatric brain tumor. Surgical excision of these tumors, due to the exquisite location of the pons, is dangerous and is not curative. No chemotherapy has been identified that can control these tumors. One theory for this failure is that the pons is a unique location into which delivery of medications at therapeutic concentrations is singularly challenging. Current standard of care utilizes temozolomide (TMZ), a pro-drug that releases a DNA alkylating agent that is used to kill glial cells. TMZ is very toxic when delivered systemically and therapeutic dosages are limited by severe side effects. These factors necessitate a selectively targeted carrier for TMZ to deliver the drug efficiently to malignant cells avoiding nonspecific interaction and reducing offsite toxicity. In order to design an efficient and effective drug carrier, we addressed several issues: a tailored surface on the carrier to attach biomolecules for targeted drug delivery; a biocompatible coating which can efficiently encapsulate the hydrophobic drug thereby reducing cytotoxicity; and stimuli-induced (pH) disruption of the carrier agent for slow and controlled drug release to the desired environment. Micelles are the preferred choice of carrier as they fulfill these requirements based on their composition. Micelles containing drug are synthesized using PEG-PE-Amine and N-palmitoyl homocysteine (pH sensitive lipid breaks in endosome pH 5.5). Specific targeting of the micelles to glioblastoma cells is achieved by coupling a short 12 a.a. PDGF (platelet derived growth factor) peptide to the amine moeity of the DSPE-PEG. In addition, these micelles have been labeled with a NIR fluorophore to track them for cellular uptake and can be used to image tumor internalization in vivo. These micelles have an advantage of small size ( Citation Format: Kayla Miller, Suraj K. Dixit, Amy-Lee Bredlau, Ann-Marie Broome. Targeted delivery of temozolomide to pediatric brain tumors using micelle-based theranostic nanocarriers. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3981. doi:10.1158/1538-7445.AM2014-3981