A primary challenge in ovarian cancer is preventing tumor recurrence in patients following a resection / debulking procedure (5-year survival rate <45%). Intraperitoneal (IP) administration of chemotherapy (most notably paclitaxel) can improve patient outcomes and prevent local tumor recurrence (the principal deterrent to long-term survival). However, despite these modest improvements, there are significant limitations to this therapy. For example, the current clinical formulation of paclitaxel (i.e., Taxol) is: A) limited due to toxic side effects resulting from absorption across the entire surface of the peritoneal cavity with no mechanism for tumor specificity; and, B) rapidly cleared from the peritoneal cavity (<10% remaining after 6 hours) resulting in sub- therapeutic levels within the tumor tissue. The proposed research uses a novel, patented technology, the expansile nanoparticle (eNP), to target the primary observable cause of patient relapse (locally recurrent IP tumor) and address these challenges. eNPs decrease toxicity and increased efficacy via: a) unique Materials- Based Targeting, which leads to preferential uptake in tumors; and, b) triggered drug release following particle swelling, which occurs in response to exposure to lowered pH (5-6.5) found in the tumor microenvironment or in the endosomes of tumor cells. Preliminary data demonstrate that, following IP administration, paclitaxel- loaded-eNPs (PTX-eNPs): 1) accumulate in both microscopic (<1 mm) and large (0.5 cm ? 1 cm) IP tumors via Materials-based Targeting without the need for targeting ligands?this characteristic is hypothesized to result from: 1a) the rapid metabolism of cancer cells vs. healthy cells; and, 1b) swelling of the eNPs within tumor cells which disrupts endosomal / autophagosomal turnover and leads to intracellular accumulation of eNPs; 2) exhibit greater in vitro cytotoxicity than Taxol against multi-drug resistant patient samples?this is hypothesized to result from the formation of an intracellular ?drug depot? upon eNP internalization that overcomes cellular evacuation of drug; 3) deliver 10- to 1000-fold higher intratumoral concentrations of paclitaxel than Taxol over a seven day period following injection; and, 4) reduce the amount of recurrent ovarian tumor by 3-fold (v. Taxol) and more than double survival (v. Taxol) in a multiple-dose treatment of IP mesothelioma model (similarly diffuse/widespread disease presentation in the peritoneum). A key Go/No-Go decision regarding the commercialization of this technology is addressed herein, via: 1) determination of the PTX-eNP maximum tolerated dose (MTD) and identification of target organs and toxicity (which may differ from Taxol due to the pharmacokinetics and distribution of the carrier; i.e., eNPs); and, 2) definitive and robust evaluation of PTX-eNPs v. Taxol to determine the value of further preclinical development of this technology. Thus, the aims are:
Aim 1) Determine the MTD of PTX-eNPs, the target organs and characteristic toxicity when administered IP; and, Aim 2) Determine the maximum efficacy of PTX-eNPs in treating ovarian cancer.
Intraperitoneal administration of chemotherapy (e.g., paclitaxel) is a promising means of preventing local tumor recurrence in patients with ovarian cancer. However, new drug delivery technologies are needed to overcome the limitations of current treatments (e.g., no mechanism for tumor targeting; rapid drug clearance from the peritoneal cavity and tumor tissue; and, dose-limiting toxicities). This SBIR Phase I proposal furthers the development of a paclitaxel-loaded, nanoparticle-based drug delivery system that employs a novel Materials- Based Targeting strategy to meet this need and determines the maximum tolerated dose and maximum therapeutic efficacy compared to the clinically used formulation; the outcome will answer whether this technology meets the prospective, quantitative Go/No-Go criteria necessary for further development.