Phase I study of paclitaxel administered by ten-day continuous infusion

Synthesis of poly(1,2-glycerol carbonate)-paclitaxel conjugates and their utility as a single high-dose replacement for multi-dose treatment regimens in peritoneal cancer

A high drug-density, biodegradable polymeric nanocarrier replaces multi-dose paclitaxel treatment regimens.

Current chemotherapeutic dosing strategies are limited by the toxicity of anticancer agents and therefore rely on multiple low-dose administrations. As an alternative, we describe a novel sustained-release, biodegradable polymeric nanocarrier as a single administration replacement of multi-dose paclitaxel (PTX) treatment regimens. The first synthesis of poly(1,2-glycerol carbonate)-graft-succinic acid-paclitaxel (PGC–PTX) is described, and its use enables high, controlled PTX loadings of up to 74 wt%. Moreover, the polymer backbone is composed of biocompatible building blocks—glycerol and carbon dioxide. When formulated as nanoparticles (NPs), PGC–PTX NPs exhibit PTX concentrations >15 mg mL^–1, sub-100 nm diameters, narrow dispersity, storage stability for up to 6 months, and sustained and controlled PTX release kinetics over an extended period of 70 days. A safely administered single dose of PGC–PTX NPs contains more PTX than the median lethal dose of standard PTX. In murine models of peritoneal carcinomatosis, in which the clinical implementation of multi-dose intraperitoneal (IP) treatment regimens is limited by catheter-related complications, PGC–PTX NPs exhibit improved safety at high doses, tumor localization, and efficacy even after a single IP injection, with comparable curative effect to PTX administered as a multi-dose IP treatment regimen.

Paclitaxel-loaded PEG-PE-based micellar nanopreparations targeted with tumor-specific landscape phage fusion protein enhance apoptosis and efficiently reduce tumors

In an effort to improve the therapeutic index of cancer chemotherapy, we developed an advanced nanopreparation based on the combination of landscape phage display to obtain new targeting ligands with micellar nanoparticles for tumor targeting of water-insoluble neoplastic agents. With paclitaxel as a drug, this self-assembled nanopreparation composed of MCF-7-specific phage protein and polyethylene glycol-phosphatidylethanolamine (PEG-PE) micelles showed selective toxicity to target cancer cells rather than nontarget, non cancer cells in vitro. In vivo, the targeted phage micelles triggered a dramatic tumor reduction and extensive necrosis as a result of improved tumor delivery of paclitaxel. The enhanced anticancer effect was also verified by an enhanced apoptosis and reduced tumor cell proliferation following the treatment with the targeted micellar paclitaxel both in vitro and in vivo. The absence of hepatotoxicity and pathologic changes in tissue sections of vital organs, together with maintenance of overall health of mice following the treatment, further support its translational potential as an effective and safe chemotherapy for improved breast cancer treatment.

Combined drug release from biodegradable bilayer coating for endovascular stents

In this work, the characterization of a biodegradable bilayer system, used as controlled and combined drug delivery platform, is reported. For this aim, a bilayer system, composed of poly(lactic-co-glycolic acid) and poly(3-hydroxybutyric-co-3-hydroxyvaleric acid), was investigated under physicochemical and functional aspects by evaluating polymer/polymer and polymer/stent material interactions, the kinetic of in vitro degradation, and drug release properties, comparing results with the monolayer reference systems. Obtained results showed that the bilayer system allowed increasing the total amount of eluted Tacrolimus and Paclitaxel drugs with respect to the monolayer systems in the considered testing period and conditions. This evidence was associated to a faster degradation of the tested copolymers in the bilayered configuration, excluding a synergic effect of two drugs on delivery performance. In addition, a macromolecular relaxation process was identified to govern the PLX release from poly(lactic-co-glycolic acid), whereas a pure Fickian diffusion occurred in the delivery of Tacrolimus from poly(3-hydroxybutyric-co-3-hydroxyvaleric acid).

Treatment of anaplastic thyroid carcinoma with paclitaxel: phase 2 trial using ninety-six-hour infusion. Collaborative Anaplastic Thyroid Cancer Health Intervention Trials (CATCHIT) Group

Anaplastic thyroid carcinoma is a rare, lethal disease with no effective systemic therapies. Preclinical studies demonstrated antineoplastic activity of paclitaxel. This prompted a prospective phase 2 clinical trial to determine activity of paclitaxel against anaplastic thyroid carcinoma in patients with persistent or metastatic disease despite surgery or local radiation therapy. Twenty patients, entered through 6 of 12 study sites, were treated with 96-hour continuous infusion paclitaxel every 3 weeks for 1 to 6 cycles; the first 7 patients received 120 mg/m2 per 96 hours and the rest received 140 mg/m2 per 96 hours. Total responses to therapy were assessed using modified criteria with response durability acceptable at 2 or more weeks, due to the exceedingly rapid growth rate of this tumor. Plasma samples were obtained for pharmacokinetic analyses. Off-protocol, data showed that 9 patients were later treated with 225 mg/m2 paclitaxel as weekly 1-hour infusions. Nineteen evaluable patients demonstrated a 53% total response rate (95% confidence interval, 29%-76%) with one complete response and nine partial responses (including one off protocol). Results of historical review off-protocol showed 2 of 7 patients, with prior partial responses to the 96-hour infusion, had subsequent partial responses to weekly treatment and 1 of 2 prior nonresponders gained a partial response to weekly therapy. No toxicities greater than grade 2 were seen with 96-hour infusions, while peripheral neuropathy (up to grade 3) was most common with postprotocol weekly infusions. Paclitaxel appears to be the only agent with significant clinical systemic activity against anaplastic thyroid carcinoma; however, it is not capable of altering the lethality of this malignancy, suggesting the need for additional therapeutic innovations. Decreased time intervals between paclitaxel infusions may be more efficacious.

Inter-relationships of paclitaxel disposition, infusion duration and cremophor EL kinetics in cancer patients

Cremophor EL (CrEL) is a castor oil surfactant used as a vehicle for formulation of a variety of poorly water-soluble agents, including paclitaxel. Recently, we found that CrEL can influence the in vitro blood distribution of paclitaxel by reducing the free drug fraction, thereby altering drug accumulation in erythrocytes. The purpose of this study was to investigate the clinical pharmacokinetics of CrEL, and to examine inter-relationships of paclitaxel disposition, infusion duration and CrEL kinetics. The CrEL plasma clearance, studied in 17 patients for a total of 28 courses, was time dependent and increased significantly with prolongation of the infusion duration from 1 to 3 to 24 h (p<0.03). An indirect response model, applied based on use of a Hill function for CrEL concentration-dependent alteration of in vivo blood distribution of paclitaxel, was used to fit experimental data of the 3 h infusion (r2=0.733; p=0.00001). Simulations for 1 and 24 h infusions using predicted parameters and CrEL kinetic data revealed that both short and prolonged administration schedules induce a low relative net change in paclitaxel blood distribution. Our pharmacokinetic/pharmacodynamic model demonstrates that CrEL causes disproportional accumulation of paclitaxel in plasma in a 3 h schedule, but is unlikely to affect drug pharmacokinetics in this manner with alternative infusion durations.