TARGETED DELIVERY OF A NOVEL COMBINATION THERAPY FOR NEUROBLASTOMA

Purpose: Neuroblastoma (NB) is the most common solid extra-cranial tumor found in children. The prognosis for late stage or high risk Neuroblastoma patients remains very low despite very intense multi-modal therapies. The patients that do survive, and reach remission from aggressive NB have a much increased risk of developing cancer again later in life. Therefore it is important to increase the efficacy of the current treatments, while decreasing their toxic side effects in order to raise these patients' standard of living. One of the novel therapies currently being explored for NB is a combination of the chemotherapeutic agent Imatinib Mesylate (Imatinib), a tyrosine kinase inhibitor specific for c-kit and platelet derived growth factor receptor, both of which are expressed on NB cells, and Saquinavir, a protease inhibitor with anti-cancer properties, that is currently used in anti-HIV therapy. Previous studies have shown Saquinavir to be effective against Chronic Myeloid Leukemia cells; therefore we anticipate that it might also be effective against NB cells and tumors. We propose that the encapsulation of this combination of drugs into our reconstituted high density lipoprotein (rHDL) system will not only improve their therapeutic action against NB, but will also reduce their off target toxicity, via amount of toxic side effects due to the selective delivery properties of the rHDL Nanoparticles. Methods: The rHDL particles were prepared using the cholate dialysis method. The particles were then characterized for their physical properties and chemical composition. Size of the particles was determined using dynamic light scattering. SJ-N-KP and SMS-KCNR cells were plated in 96 well plates at a concentration of 5 x 103 cells per well. The Dojindo CCK8 test was used to measure cytotoxicity for both free and encapsulated Imatinib and Saquinavir after 48 hour exposure to the drugs. Results: The mean diameter of the Imatinib-rHDL particles was found to be 97.1 nm, and the mean diameter of the Saquinavir-rHDL particles was found to be 33.1 nm. Encapsulation of the Saquinavir into rHDL nanoparticles has shown up to a 100 fold increase in cytotoxicity in NB cell lines. Conclusions: Our studies show that encapsulation of this novel drug combination into rHDL nanoparticles greatly increases their efficacy against NB cell lines, thus indicating the potential of this system in combination to improve therapy, and raise the prognosis of NB patients.