Formulating adjuvant therapy of rHDL nanoparticles with saquinavir to combat high-risk neuroblastoma.

Purpose: Despite major advances in pediatric cancer research, there has been only modest progress in the survival of children with high risk neuroblastoma (HRNB). Current chemotherapy regimens have a serious limitation due to off target toxicity. The purpose of our project is to evaluate the effectiveness of a drug delivery platform with reconstituted/synthetic high density lipoprotein nanoparticles (rHDL) using rHDL-saquinavir formulation for the treatment of HRNB. It is anticipated that upon establishing an improved chemotherapeutic regimen for HRNB, the rHDL technology could be extended to enhance the chemotherapy for other pediatric cancers. Materials and Methods: The rHDL-Saquinavir nanoparticles were prepared by cholate dialysis method. The entrapment efficiency of Saquinavir was determined by Fluorimetric measurements. The chemical composition of rHDL/Saquinavir particles was estimated by standard kits. The average size of the particles was measured by DeLsa Nano particle size analyzer. The stability of particles was estimated by dialyzing the particles at 37°C, for 48 hours at pH 7.4. The cytotoxic effectiveness of the formulation was tested against two HRNB cell lines (SJNKP and IMR-5 obtained from Dr F. Temius, Regina Margherita Children’s Hospital, Turin, Italy)) as compared to that of the free Saquinavir using CCK-8 kit. The Inhibitory concentration to kill 50% of the cells (IC50) was determined. Results: The entrapment efficiency of the rHDL-SAQ particles was determined to be 70%. The chemical composition study indicated that the rHDL-SAQ nanoparticles were composed of 60% phospholipids, 24% protein, 9% cholesterol, and 7% of Saquinavir. The average diameter of the particle was 7.3 nm. The stability of the nanoparticle formulation measured as retention of the drug under experimental conditions indicated that 71% of the drug was preserved. When testing the survival of the IMR-5 cell lines in presence of Free and rHDL-Saquinavir, it was found that the rHDL particles were 10 times more effective than free Saquinavir. The effect on the SJNKP cells was observed to be 2 fold greater when using the rHDL particles compared to the free drug. Moreover, the rHDL-SAQ particles were both able to achieve 100% killing while the free SAQ did not achieve 100% killing effect in the given range. Conclusions: The rHDL-Saquinavir nanoparticles were successfully formulated. The particles appeared to be small, stable and non-leaking. In vitro survival studies suggested that rHDL-Saquinavir formulation is more effective than the free saquinavir. Thus, these studies support the potential of this novel drug delivery platform for treating HRNB. These studies could be extended to other types of cancers as well.