Preclinical evaluation of alternative pharmaceutical delivery vehicles for paclitaxel

Out of Control? Managing Baseline Variability in Experimental Studies with Control Groups

Control groups are expected to show what happens in the absence of the intervention of interest (negative control) or the effect of an intervention expected to have an effect (positive control). Although they usually give results we can anticipate, they are an essential component of all experiments, both in vitro and in vivo, and fulfil a number of important roles in any experimental design. Perhaps most importantly they help you understand the influence of variables that you cannot fully eliminate from your experiment and thus include them in your analysis of treatment effects. Because of this it is essential that they are treated as any other experimental group in terms of subjects, randomisation, blinding, etc. It also means that in almost all cases, contemporaneous control groups are required. Historical and baseline control groups serve a slightly different role and cannot fully replace control groups run as an integral part of the experiment. When used correctly, a good control group not only validates your experiment; it provides the basis for evaluating the effect of your treatments.

The drug delivery field at the inflection point: Time to fight its way out of the egg

The world is becoming a better place, in part, by breakthrough findings by scientists. In the drug delivery field, many breakthrough formulations have been achieved helping patients deal with various diseases effectively. The recent progress, however, has been slowing down, and many important drug delivery problems have not been resolved. They can be overcome by understanding the causes and finding the remedies. For the last three decades, the field has been overwhelmed by nanotechnology, nanomedicine, and many nano-sized drug delivery systems. Disappointing outcomes of nano-sized formulations (nanoformulations) in clinical studies indicate that our overall approach of nanomedicine needs serious reevaluation. The limited advantages of nanoformulations were drastically exaggerated, and the assumptions used in nanomedicine and nanoformulations turned out to be inapplicable to clinical applications. The drug delivery field is at the strategic inflection point, and we all have to face the reality by absorbing the inconvenient truth and fight our way out of the egg to break the ill-conceived illusion of nanomedicine. Scientists are proud of their independent thinking and their work that can change the world, but the current climate does not allow them to be true scientists. The future of the drug delivery field depends on how effectively we can find talented young scientists with motivation, cultivate them with resources, provide them with an environment for the free exchange of ideas, and nurture them with purpose, passion, and the conviction of doing meaningful science.

Nanoparticles of biodegradable polymers for new-concept chemotherapy

The current regimen of chemotherapy is far from satisfactory--its efficiency is limited and patients suffer from serious side effects. Various drug delivery devices have been under intensive investigation in the past few decades in attempts to develop controlled and targeted methods of chemotherapy administration. This article reviews the latest developments in nanoparticles of biodegradable polymers for chemotherapy of cancer and other diseases such as cardiovascular restenosis. The preliminary results obtained in the author's laboratory are used to demonstrate the concept. This review is written with the belief that engineering, in particular, chemical engineering principles, can be applied and further developed to solve the problems in the current practice of chemotherapy and promote a new concept of chemotherapy - chemotherapy at home.

Dairy milk fat augments paclitaxel therapy to suppress tumour metastasis in mice, and protects against the side-effects of chemotherapy

Milk fat is a natural product containing essential nutrients as well as fatty acids and other food factors with reported anti-cancer potential. Here bovine milk fat was tested for its ability to inhibit the growth of breast and colon cancers and their metastasis to the lung and liver; either alone or in combination with the chemotherapeutic agent paclitaxel. A diet containing 5% typical anhydrous milk fat (representing ~70% of the total dietary fat component) fed to Balb/c mice delayed the appearance of subcutaneous 4T1 breast and CT26 colon cancer tumours and inhibited their metastasis to the lung and liver, when compared to the control diet containing soybean oil as the only fat component. It augmented the inhibitory effects of paclitaxel on tumour growth and metastasis, and reduced the microvessel density of tumours. It displayed no apparent organ toxicity, but instead was beneficial for well-being of tumour-bearing mice by maintaining gastrocnemius muscle and epididymal adipose tissue that were otherwise depleted by cachexia. The milk fat diet ameliorated gut damage caused by paclitaxel in non-tumour-bearing mice, as evidenced by retention of jejunal morphology, villi length and intestinal γ-glutamyl transpeptidase activity, and inhibition of crypt apoptosis. It prevented loss of red and white blood cells due to both cancer-mediated immunosuppression and the cytotoxic effects of chemotherapy. The present study warrants the use of milk fat as an adjuvant to inhibit tumour metastasis during cancer chemotherapy, and to spare patients from the debilitating side-effects of cytotoxic drugs.

Complement activation by polyethoxylated pharmaceutical surfactants: Cremophor-EL, Tween-80 and Tween-20

Immunosafety analysis of pharmaceutical surfactants is an important step in understanding the complex mechanisms by which they induce side effects in susceptible patients. This paper provides experimental evidences that polyethoxylated surfactants, Cremophor-EL and Tween-80, also known as Polysorbate-80, activate the complement system in vitro, in normal human serum and plasma. They appeared to be more efficient reactogens than their structural homolog, Tween-20. Cremophor-EL and Tween-80 promoted the generation of biologically active complement products, C3a, C5a and C5b-9. Consistently, Paclitaxel and Taxotere (Docetaxel), pharmaceuticals formulated in Cremophor-EL and Tween-80, activated the complement system in similar extent. Moreover, comparison of serum reactivity against the drug-loaded and drug-free formulations exhibited a significant linear correlation. Taken together, these results are consistent with the hypothesis that therapeutic side effects, such as acute hypersensitivity and systemic immunostimulation, caused by intravenous nanomedicines containing polyethoxylated detergents such as Cremophor-EL and Tween-80, can be attributed to complement activation-derived inflammatory mediators.

Improving tenoxicam solubility and bioavailability by cosolvent system

The formulation study of tenoxicam, a poorly water-soluble drug, was developed by use of a ternary cosolvent system and has significantly enhanced the solubility. Additionally, the relative bioavailability of testing formulation was also evaluated by New Zealand rabbit with a single i.m. injection. The three-phase diagram for dimethylsulfoxide (DMSO)/propylene glycol/water, DMSO/ethanol/water, and DMSO/polyethoxylated castor oil/ethanol system was developed. The volume ratio of 5:4:1 in the DMSO/polyethoxylated castor oil/ethanol system resulted in a more suitable vehicle than other systems, with a high solubility (20.73 mg/ml) and low viscosity (10.0 Cp). A pharmacokinetic study of bioequivalence (F (rel) = 0.89) was also obtained. The present study not only provides a novel strategy improving tenoxicam solubility but also helps further scientific knowledge for the development of parenteral formulations.

The efficacy and safety of Padexol (paclitaxel) and cisplatin for treating advanced non-small cell lung cancer

PURPOSE

The authors conducted a multicenter study to evaluate the efficacy and safety of combination chemotherapy with Padexol and cisplatin for treating patients with advanced non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

From November 2003 to April 2005, 42 chemo-naive patients with advanced NSCLC were enrolled into this study from 4 hospitals. The treatment consisted of Padexol 175 mg/m(2) as a 3-hr infusion, and this was followed by cisplatin 75 mg/m(2) administered as an intravenous infusion with standard premedication. The treatment was repeated every 3 weeks.

RESULTS

Among the 42 patients (pts), 33 pts were evaluable for response. On the per protocol analysis, 1 patient (pt) (3.0%) achieved complete response (CR), 17 pts (51.5%) achieved partial response (PR), 6 pts (18.2%) achieved stable disease (SD), and 9 pts (27.3%) progressed; therefore, the overall response rate was 54.6% (95% CI: 37.6 approximately 71.5%). On the intention-to-treat analysis, 1 pt (2.4%) achieved CR, 18 pts (42.9%) achieved PR, 11 pts (26.2%) achieved SD, and 9 pts (21.4%) progressed; therefore, the overall response rate was 45.2% (95% CI: 30.2 approximately 60.3%). The response, as evaluated by the investigators, was independently reviewed by 2 external radiologists and it was as follows; 13 PR (43.3%), 14 SD (46.7%) and 3 progressive disease (10%). The median duration of response was 5.9 months. The median follow-up duration was 10.3 months (range: 1.3 to 22.1 months). The median time to progression was 5.8 months (95% CI: 4.7 to 7.4 months). The median survival time on the intention-to-treat analysis was 10.5 months (95% CI: 8.1 to 18.8 months). The most common grade 3 or 4 hematologic toxicities were neutropenia (26/180 cycles, 14.4%), anemia (7/180 cycles, 3.9%) and febrile neutropenia (2/180 cycles, 1.1%). The most frequent grade 3 or 4 non-hematologic toxicities were nausea (14/42 patients, 14.3%), anorexia (3/42 patients, 7.1%) and myalgia (3/42 patients, 7.1%).

CONCLUSION

The authors observed that Padexol was as good as the other paclitaxel (Taxol or Genexol) formulations when combined with cisplatin for treating patients with advanced NSCLC.

Polysorbate 80 in medical products and nonimmunologic anaphylactoid reactions

BACKGROUND

Polyoxyethylene-sorbitan-20-monooleate (also known as polysorbate 80 and Tween 80) is a solubilizing agent ubiquitously used in nutritives, creams, ointments, lotions, and multiple medical preparations (e.g., vitamin oils, vaccines, and anticancer agents) and as an additive in tablets. Whereas its relevance as a contact allergen has declined during the past decades, it is of current relevance as a "hidden" inductor of anaphylactoid reactions.

OBJECTIVE

To identify polysorbate 80 (generally believed to be an inert vehicle) as an inductor of a severe anaphylactoid reaction.

METHODS

Skin prick testing, enzyme-linked immunosorbent assay, IgE immunoblotting, and flow cytometric detection of basophil activation were performed in controls and in a patient with a medical history of anaphylactic shock due to intravenous administration of a multivitamin product during pregnancy.

RESULTS

Polysorbate 80 was identified as the causative agent for the anaphylactoid reaction of nonimmunologic origin in the patient. Polysorbate specific IgE antibodies were not identified in enzyme-linked immunosorbent assay and immunoblot examinations, confirming the nonimmunologic nature of the anaphylactoid reaction.

CONCLUSIONS

Polysorbate 80 is a ubiquitously used solubilizing agent that can cause severe nonimmunologic anaphylactoid reactions.

Paclitaxel chemotherapy: from empiricism to a mechanism-based formulation strategy

Paclitaxel is an anticancer agent effective for the treatment of breast, ovarian, lung, and head and neck cancer. Because of water insolubility, paclitaxel is formulated with the micelle-forming vehicle Cremophor EL to enhance drug solubility. However, the addition of Cremophor EL results in hypersensitivity reactions, neurotoxicity, and altered pharmacokinetics of paclitaxel. To circumvent these unfavorable effects resulting from the addition of Cremophor EL, efforts have been made to develop new delivery systems for paclitaxel administration. For example, ABI-007 is a Cremophor-free, albumin-stabilized, nanoparticle paclitaxel formulation that was found to have significantly less toxicity than Cremophor-containing paclitaxel in mice. Pharmacokinetic studies indicate that in contrast to Cremophor-containing paclitaxel, ABI-007 displays linear pharmacokinetics over the clinically relevant dose range of 135-300 mg/m(2). In a phase III study conducted in patients with metastatic breast cancer, patients treated with ABI-007 achieved a significantly higher objective response rate and time to progression than those treated with Cremophor-containing paclitaxel. Together these findings suggest that nanoparticle albumin-bound paclitaxel may enable clinicians to administer paclitaxel at higher doses with less toxicity than is seen with Cremophor-containing paclitaxel. The role of this novel paclitaxel formulation in combination therapy with other antineoplastic agents needs to be determined.

Local, non-viral IL-12 gene therapy using a water soluble lipopolymer as carrier system combined with systemic paclitaxel for cancer treatment

Development of improved gene transfer methods is needed for gene therapy to achieve its clinical potential. The use of biocompatible polymeric gene carriers has shown effectiveness in overcoming the current problems associated with viral vectors in safety, immunogenicity and mutagenesis. Previous work has demonstrated that repeated, local, non-viral interleukin-12 (IL-12) gene delivery successfully slows down tumor progression, while improving immunogenicity. Combining IL-12 gene delivery with systemic paclitaxel (PCT) chemotherapy as a treatment for various subcutaneous mouse mammary carcinomas, we used PCT with either a biodegradable polymeric solubilizer, HySolv or Cremophor EL for systemic treatment and injected water soluble lipopolymer (WSLP)/plasmid-encoding IL-12 gene (p2CMVmIL-12) complexes local once every week. The amount of lung metastases being essential for survival as well as subcutaneous tumor volume were compared against untreated controls. We showed inhibition of tumor growth and decreased lung metastases in the combined WSLP/p2CMVmIL-12/HySolv group compared to the controls and the PCT only treated groups. Compared to Cremophor, HySolv performed better alone or in combination with IL-12. Using polymeric vectors as gene carrier systems in combination with improved systemic therapies provide evidence for the efficacy and feasibility of polymer-based drug delivery systems. Especially local cytokine gene delivery showed augmentation of systemic chemotherapy while reducing the hosts risk for further systemic toxicity.

A phase I and pharmacokinetic study of BAY59: a novel taxane

PURPOSE

To determine the maximum tolerated dose (MTD), the dose limiting toxicities (DLT) and the pharmacokinetics of BAY59, a novel taxane given as a 1-hour intravenous infusion every 3 weeks in patients with advanced refractory solid tumors.

EXPERIMENTAL DESIGN

Initially, 15 patients with previously treated (median of 4 prior chemotherapy regimens) refractory cancers, but with normal marrow, hepatic and renal function were treated with BAY59 at doses of 15, 30, 50, 75 and 100 mg/m2 using a standard dose escalation design. Subsequently, 11 patients were treated, 5 at 90 mg/m2 and 6 who had had prior oxaliplatin at 75 mg/m2.

RESULTS

At 75 mg/m2, grade 4 neutropenia was noted in 2/6 patients, of whom 1 had grade 4 neutropenia lasting more than 5 days (DLT). At 100 mg/m2, 2/2 patients had febrile neutropenia, with 1 fatality. At 90 mg/m2, 2/5 patients had DLTs, including grade 3 neuropathy, severe lower extremity pain, dehydration and grade 4 neutropenia. The MTD was determined to be 75 mg/m2. A cohort of 6 patients, previously exposed to oxaliplatin, were enrolled at the MTD to evaluate the incidence of neurotoxicity. While DLTs (grade 3 arthralgia, grade 4 neutropenia) were noted in 3/6 patients, there was no increase in the incidence of neurotoxicity. There were no responses. Pharmacokinetics of BAY59 was linear over the doses studied, with a median terminal half-life of 21 h.

CONCLUSIONS

The recommended phase II dose for BAY59 is 75 mg/m2.

Combination of local, nonviral IL12 gene therapy and systemic paclitaxel treatment in a metastatic breast cancer model

Repeated, local, nonviral IL12 (interleukin-12) gene delivery decreased tumor progression and increased immunogenicity. We combined our IL12 gene delivery with systemic paclitaxel chemotherapy as a treatment for paclitaxel (PCT)-resistant 4T1 subcutaneous mouse mammary carcinomas and PCT-sensitive, immunogenic/nonimmunogenic tumors. We mixed PCT with either a biodegradable polymeric solubilizer, HySolv, or Cremophor EL for bimonthly systemic treatments and injected water-soluble lipopolymer (WSLP)/p2CMVmIL-12 (plasmid encoding IL12 gene) complexes locally every week. We compared treated subcutaneous tumor volume and lung metastasis with controls. HySolv alone performed better compared to Cremophor EL in combination with WSLP/p2CMVmIL-12. We showed inhibition of 4T1 tumor growth and lung metastases in the combined WSLP/p2CMVmIL-12/HySolv group compared to the controls and the paclitaxel-only treated groups. In parallel experiments we also demonstrated additive responses for tumor growth and number of lung metastases within other PCT-sensitive mammary tumor models using this combination strategy. Our combination therapy provides evidence for the efficacy and feasibility of improved drug delivery systems. Local cytokine gene delivery can augment local and systemic chemotherapy without placing the host at risk for further systemic toxicity.

Phase I and pharmacokinetic study of Genexol-PM, a cremophor-free, polymeric micelle-formulated paclitaxel, in patients with advanced malignancies

PURPOSE

The rationale for developing an alternative paclitaxel formulation concerns Cremophor EL-related side effects, and a novel paclitaxel delivery system might augment its therapeutic efficacy. Genexol-PM is a polymeric micelle formulated paclitaxel free of Cremophor EL. A phase I study was performed to determine the maximum tolerated dosage, dose-limiting toxicities, and the pharmacokinetic profile of Genexol-PM in patients with advanced, refractory malignancies.

EXPERIMENTAL DESIGN

Twenty-one patients were entered into the study. Genexol-PM was i.v. administered over 3 h every 3 weeks without premedication. The Genexol-PM dose was escalated from 135 mg/m(2) to 390 mg/m(2).

RESULTS

All of the patients were evaluable for toxicity and response. Acute hypersensitivity reactions were not observed. Neuropathy and myalgia were the most common toxicities. During cycle 1, grade 3 myalgia occurred in 1 patient at 230 and 300 mg/m(2), respectively. At 390 mg/m(2), 2 of 3 patients developed grade 4 neutropenia or grade 3 polyneuropathy. Therefore, the maximum tolerated dosage was determined to be 390 mg/m(2). There were 3 partial responses (14%) among the 21 patients. Of the 3 responders, 2 were refractory to prior taxane therapy. The paclitaxel area under the curve from time 0 to infinity and peak or maximum paclitaxel concentration seemed to increase with escalating dose, except at 230 mg/m(2), which suggests that Genexol-PM has linear pharmacokinetics.

CONCLUSION

The main dose-limiting toxicities were neuropathy, myalgia, and neutropenia, and the recommended dosage for a phase II study is 300 mg/m(2). Genexol-PM is believed to be superior to conventional paclitaxel in terms of the obviation of premedication and the delivery of higher paclitaxel doses without additional toxicity.

Simultaneous analysis of docetaxel and the formulation vehicle polysorbate 80 in human plasma by liquid chromatography/tandem mass spectrometry

An analytical procedure for the simultaneous determination of the anticancer agent docetaxel (Taxotere) and its formulation vehicle polysorbate 80 (Tween 80) in human plasma samples is described. Sample pretreatment involved a double liquid-liquid extraction step with a mixture of acetonitrile/n-butyl chloride (1/4, v/v). Separation of the compounds of interest, including the internal standard paclitaxel, was achieved on a reversed-phase Waters X-Terra mass spectrometry (MS) column (50 x 2.1mm internal diameter) packed with a 3.5-microm octadecyl stationary phase, using isocratic elution. Detection of docetaxel and polysorbate 80 was performed using tandem MS detection with electrospray ionization. Validation results indicated that the method is accurate and precise and has lower limits of quantitation of 0.500 nM (approximately 0.4 ng/ml) and 1.00 microg/ml for docetaxel and polysorbate 80, respectively. The method was subsequently used to measure concentrations of docetaxel and polysorbate 80 in plasma samples in support of a project to assess the influence of polysorbate 80 concentrations on the disposition and toxicity profile of docetaxel in cancer patients receiving Taxotere.

Pharmacological effects of formulation vehicles : implications for cancer chemotherapy

The non-ionic surfactants Cremophor EL (CrEL; polyoxyethyleneglycerol triricinoleate 35) and polysorbate 80 (Tween) 80; polyoxyethylene-sorbitan-20-monooleate) are widely used as drug formulation vehicles, including for the taxane anticancer agents paclitaxel and docetaxel. A wealth of recent experimental data has indicated that both solubilisers are biologically and pharmacologically active compounds, and their use as drug formulation vehicles has been implicated in clinically important adverse effects, including acute hypersensitivity reactions and peripheral neuropathy.CrEL and Tween 80 have also been demonstrated to influence the disposition of solubilised drugs that are administered intravenously. The overall resulting effect is a highly increased systemic drug exposure and a simultaneously decreased clearance, leading to alteration in the pharmacodynamic characteristics of the solubilised drug. Kinetic experiments revealed that this effect is primarily caused by reduced cellular uptake of the drug from large spherical micellar-like structures with a highly hydrophobic interior, which act as the principal carrier of circulating drug. Within the central blood compartment, this results in a profound alteration of drug accumulation in erythrocytes, thereby reducing the free drug fraction available for cellular partitioning and influencing drug distribution as well as elimination routes. The existence of CrEL and Tween 80 in blood as large polar micelles has also raised additional complexities in the case of combination chemotherapy regimens with taxanes, such that the disposition of several coadministered drugs, including anthracyclines and epipodophyllotoxins, is significantly altered. In contrast to the enhancing effects of Tween 80, addition of CrEL to the formulation of oral drug preparations seems to result in significantly diminished drug uptake and reduced circulating concentrations. The drawbacks presented by the presence of CrEL or Tween 80 in drug formulations have instigated extensive research to develop alternative delivery forms. Currently, several strategies are in progress to develop Tween 80- and CrEL-free formulations of docetaxel and paclitaxel, which are based on pharmaceutical (e.g. albumin nanoparticles, emulsions and liposomes), chemical (e.g. polyglutamates, analogues and prodrugs), or biological (e.g. oral drug administration) strategies. These continued investigations should eventually lead to more rational and selective chemotherapeutic treatment.