We assessed the efficacy of the polymeric nanoparticle containing docetaxel (PNP-DTX) in preclinical mouse models and determined the maximum tolerated dose (MTD) through clinical study. Subcutaneous and orthotopic mouse models were dedicated. Tumor growth delay in orthotopic model and quantification of in vivo imaging in orthotopic model were evaluated. Phase I clinical study was a single-center, prospective, open-label trial in advanced solid tumors. PNP-DTX was injected intravenously and the starting dose was 20 mg/m2 escalated to 35 mg/m2, 45 mg/m2, 60 mg/m2 and 75 mg/m2. Pharmacokinetics, tumor response, toxicities were evaluated. Preclinical result revealed the more potent cytotoxic effect of PNP-DTX than docetaxel (DTX). However, there was no difference between PNP-DTX and DTX in subcutaneous model. Tubulin polymerization assay showed that PNP-DTX preserved original mode of action of DTX. For phase I clinical trial, 18 patients were analyzed. The dose of 75 mg/m2 was tentatively determined as the MTD and the most common toxicity was grade 4 neutropenia not lasting over 7days. The Cmax of 60 mg/m2 PNP-DTX and AUClast of 45 mg/m2 PNP-DTX were measured to be comparable to those of 75 mg/m2 DTX. Partial remission (PR) was achieved in 4 (22%) patients. The potency of PNP-DTX was revealed especially in orthotopic mouse model. The MTD of PNP-DTX could not be confirmed, but 75 mg/m2 was tentatively determined. The PNP-DTX of 45 mg/m2 had the same pharmacokinetic profile with that of 75 mg/m2 DTX.
Keywords: MTD; PNP-DTX; efficacy; pancreas; phase I.