Tapas De

Increased antitumor activity, intratumor paclitaxel concentrations, and endothelial cell transport of cremophor-free, albumin-bound paclitaxel, ABI-007, compared with cremophor-based paclitaxel.

ABI-007, an albumin-bound, 130-nm particle form of paclitaxel, was developed to avoid Cremophor/ethanol-associated toxicities in Cremophor-based paclitaxel (Taxol) and to exploit albumin receptor-mediated endothelial transport. We studied the antitumor activity, intratumoral paclitaxel accumulation, and endothelial transport for ABI-007 and Cremophor-based paclitaxel. Antitumor activity and mortality were assessed in nude mice bearing human tumor xenografts [lung (H522), breast (MX-1), ovarian (SK-OV-3), prostate (PC-3), and colon (HT29)] treated with ABI-007 or Cremophor-based paclitaxel. Intratumoral paclitaxel concentrations (MX-1-tumored mice) were compared for radiolabeled ABI-007 and Cremophor-based paclitaxel. In vitro endothelial transcytosis and Cremophor inhibition of paclitaxel binding to cells and albumin was compared for ABI-007 and Cremophor-based paclitaxel. Both ABI-007 and Cremophor-based paclitaxel caused tumor regression and prolonged survival; the order of sensitivity was lung > breast congruent with ovary > prostate > colon. The LD(50) and maximum tolerated dose for ABI-007 and Cremophor-based paclitaxel were 47 and 30 mg/kg/d and 30 and 13.4 mg/kg/d, respectively. At equitoxic dose, the ABI-007-treated groups showed more complete regressions, longer time to recurrence, longer doubling time, and prolonged survival. At equal dose, tumor paclitaxel area under the curve was 33% higher for ABI-007 versus Cremophor-based paclitaxel, indicating more effective intratumoral accumulation of ABI-007. Endothelial binding and transcytosis of paclitaxel were markedly higher for ABI-007 versus Cremophor-based paclitaxel, and this difference was abrogated by a known inhibitor of endothelial gp60 receptor/caveolar transport. In addition, Cremophor was found to inhibit binding of paclitaxel to endothelial cells and albumin. Enhanced endothelial cell binding and transcytosis for ABI-007 and inhibition by Cremophor in Cremophor-based paclitaxel may account in part for the greater efficacy and intratumor delivery of ABI-007.

Abstract 2193: Stabilityof injectable phospholipid nanoparticles loaded with paclitaxel: influence oflipid composition, drug concentration, storage temperature, lyophilization, andadditives

Paclitaxel is one of the most effective chemotherapeutic drugs for solid tumors including breast, lung and ovarian cancers. It has been formulated as a nanoparticle formulation, Abraxane, to improve its solublity (0.35-0.7 μg/mL) and to avoid the use of harmful solvents like cremophor EL. We previously reported the next-generation Abraxane - Cynviloq - a polymeric micelle paclitaxel formulation which uses a chemical polymer instead of biological polymer to stabilize the nanoparticle [1]. Here we investigate and report the use of phospholipids instead of a chemical polymer for the creation of the next-generation Abraxane. The effect of lipid composition on drug loading and physical stability of paclitaxel-loaded lipid-coated nanoparticle formulation was evaluated before and after lyophilization. The nanoparticles were prepared by microfluidization-solvent evaporation method. The formulation parameters included type of phospholipids, phospholipid fatty acid chain length, ratio of phospholipid and lysophospholipid combination, and drug-phospholipid ratio. The process parameters such as microfluidization pressure and number of microfluidization cycles were studied and their impact on drug loading, particle size and physical stability were evaluated. The short-term stability evaluation of nanoparticles prepared with different phospholipid ratios demonstrated that 4:1 as the optimum phospholipid-lysophospholipid ratio to achieve a loading of more than 60% paclitaxel with particle size of approximately ∼200nm. The nanoparticle size increased with an increase of carbon chain length of the phospholipid fatty acid, but no significant trends were observed for drug loading with changes in microfluidization pressure or number of cycles. The stability of the formulation was evaluated at different temperatures before and after lyophilization. The optimization of phospholipid composition, drug-lipid ratio, process parameters and additives for stability on lyophilization led to a physically stable paclitaxel-loaded phopholipid-coated nanoparticulate formulation that maintains size, charge and particulate integrity during storage. Phospholipid bound paclitaxel nanoparticle was successfully manufactured in lab scale with the desired properties. Scaling up and additional work-up for clinical evaluation is being evaluated. Reference: 1. Motamed K, Goodman Y, Hwang L, Hsiao C, Trieu V. (2014). IG-001 - A non-biologic nanoparticle paclitaxel for the treatment of solid tumors. J Nanomater Mol Nanotechnol 3:1. doi:10.4172/2324-8777.1000136. Citation Format: Shrada Prabhulkar, Gary Williams, Steve Miller, Zachary Yim, Walter McConathy, Tapas De. Stabilityof injectable phospholipid nanoparticles loaded with paclitaxel: influence oflipid composition, drug concentration, storage temperature, lyophilization, andadditives. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2193.