Phase I/II study of DHA-paclitaxel in combination with carboplatin in patients with advanced malignant solid tumours

Investigating the crucial roles of aliphatic tails in disulfide bond-linked docetaxel prodrug nanoassemblies

Disulfide bond-bridging strategy has been extensively utilized to construct tumor specificity-responsive aliphatic prodrug nanoparticles (PNPs) for precise cancer therapy. Yet, there is no research shedding light on the impacts of the saturation and cis-trans configuration of aliphatic tails on the self-assembly capacity of disulfide bond-linked prodrugs and the in vivo delivery fate of PNPs. Herein, five disulfide bond-linked docetaxel-fatty acid prodrugs are designed and synthesized by using stearic acid, elaidic acid, oleic acid, linoleic acid and linolenic acid as the aliphatic tails, respectively. Interestingly, the cis-trans configuration of aliphatic tails significantly influences the self-assembly features of prodrugs, and elaidic acid-linked prodrug with a trans double bond show poor self-assembly capacity. Although the aliphatic tails have almost no effect on the redox-sensitive drug release and cytotoxicity, different aliphatic tails significantly influence the chemical stability of prodrugs and the colloidal stability of PNPs, thus affecting the in vivo pharmacokinetics, biodistribution and antitumor efficacy of PNPs. Our findings illustrate how aliphatic tails affect the assembly characteristic of disulfide bond-linked aliphatic prodrugs and the in vivo delivery fate of PNPs, and thus provide theoretical basis for future development of disulfide bond-bridged aliphatic prodrugs.

Emerging insights on drug delivery by fatty acid mediated synthesis of lipophilic prodrugs as novel nanomedicines

Many drug molecules that are currently in the market suffer from short half-life, poor absorption, low specificity, rapid degradation, and resistance development. The design and development of lipophilic prodrugs can provide numerous benefits to overcome these challenges. Fatty acids (FAs), which are lipophilic biomolecules constituted of essential components of the living cells, carry out many necessary functions required for the development of efficient prodrugs. Chemical conjugation of FAs to drug molecules may change their pharmacodynamics/pharmacokinetics in vivo and even their toxicity profile. Well-designed FA-based prodrugs can also present other benefits, such as improved oral bioavailability, promoted tumor targeting efficiency, controlled drug release, and enhanced cellular penetration, leading to improved therapeutic efficacy. In this review, we discuss diverse drug molecules conjugated to various unsaturated FAs. Furthermore, various drug-FA conjugates loaded into various nanostructure delivery systems, including liposomes, solid lipid nanoparticles, emulsions, nano-assemblies, micelles, and polymeric nanoparticles, are reviewed. The present review aims to inspire readers to explore new avenues in prodrug design based on the various FAs with or without nanostructured delivery systems.

Synergistic Beneficial Effect of Docosahexaenoic Acid (DHA) and Docetaxel on the Expression Level of Matrix Metalloproteinase-2 (MMP-2) and MicroRNA-106b in Gastric Cancer

BACKGROUND

Gastric cancer (GC) is one of the most common cancers with the majority of patients recognized in advanced stages. The efficacy of using docosahexaenoic acid (DHA) as a supplementary agent has been suggested in treatment along with chemotherapeutics including docetaxel. However, the molecular signatures of such beneficial effects are not well-understood.

OBJECTIVE(S)

We aimed to evaluate the effects of DHA and docetaxel on the expression level of metastasis-related genes, including MMP-2 and talin-2, and their controlling miRNAs, miR-106b and miR-194, in metastatic GC cell line, MKN45.

METHOD(S)

GC cell line, MKN45, was cultured, and determination of IC50 of DHA was done by MTT test. Cells were treated with docetaxel, DHA, and their combination for 24 h, and then total RNA was extracted and cDNA synthesis was done using standard protocols. The expression level of target genes, MMP-2 and talin-2, and miR-106b and miR-194 were determined by using quantitative real-time PCR.

RESULTS

The expression level of MMP-2 was decreased significantly in all treated cells. However, talin-2 showed significant downregulation only after treatment with docetaxel. In contrary to increased expression after treatment with docetaxel, DHA led to a significant under-expression of miR-106b. The similar effect was seen for miR-194.

CONCLUSION(S)

Combination of docetaxel and DHA led to the significant downregulation of MMP-2. Also, DHA lowered the docetaxel-mediated upregulation of miR-106b oncomiR. In conclusion, supplementation of docetaxel therapy with DHA in GC patients would be considered as a beneficial approach in cancer treatment.

Tumor targeting with docosahexaenoic acid-conjugated docetaxel for inhibiting lung cancer metastasis to bone

Docetaxel (DTX) is currently used as a first- or second-line drug treatment for patients with lung cancer, however, it is less effective for the treatment of patients with bone metastasis of lung cancer. This is primarily due to the fact that docetaxel is nonspecific. In the present study, docosahexaenoic acid (DHA) was selected as a tumor-targeting ligand, and DHA-conjugated DTX (DTX-DHA) was prepared for inhibiting lung cancer metastasis to bone. The anti-cancer activity assay revealed that DTX-DHA exhibited a similar antitumor efficacy to DTX in vitro. The maximum tolerated dose of DTX-DHA was increased compared with that of DTX. The present study results indicated that DTX-DHA exhibited an improved inhibition efficacy of lung cancer metastasis to bone in comparison with DTX in vivo. Encouragingly, the mean survival time of the DTX-DHA group (30.60 days) was increased compared with the DTX group (26.10 days; P<0.01). Furthermore, the results of cell migration and osteoclast-induced formation assays suggested that DTX-DHA inhibited lung cancer metastasis to bone primarily by affecting lung cancer cell migration. These results indicate that DTX-DHA may exhibit a potential therapeutic effect against lung cancer metastasis to bone.

Biodistribution and Pharmacokinetic Evaluations of a Novel Taxoid DHA-SBT-1214 in an Oil-in-Water Nanoemulsion Formulation in Naïve and Tumor-Bearing Mice

PURPOSE

The main purpose of this study was to formulate an oil-in-water nanoemulsion of a next generation taxoid DHA-SBT-1214 and evaluate its biodistribution and pharmacokinetics.

METHODS

DHA-SBT-1214 was encapsulated in a fish oil containing nanoemulsion using a high pressure homogenization method. Following morphological characterization of the nanoemulsions, qualitative and quantitative biodistribution was evaluated in naïve and cancer stem cell-enriched PPT-2 human prostate tumor bearing mice.

RESULTS

DHA-SBT-1214 was successfully encapsulated up to 20 mg/ml in the nanoemulsion formulation and had an average oil droplet size of 200 nm. Using a DiR near infra-red dye encapsulated nanoemulsion, we have shown the delivery of nanoemulsion to mouse tumor region. By quantitative analysis, DHA-SBT-1214 encapsulated nanoemulsion demonstrated improved pharmacokinetic properties in plasma and different tissues as compared to its solution form. Furthermore, the nanoemulsions were stable and had slower in vitro drug release compared to its solution form.

CONCLUSIONS

The results from this study demonstrated effective encapsulation of the drug in a nanoemulsion and this nanoemulsion showed sustained plasma levels and enhanced tumor delivery relative to the solution form.

Self-Assembled Redox Dual-Responsive Prodrug-Nanosystem Formed by Single Thioether-Bridged Paclitaxel-Fatty Acid Conjugate for Cancer Chemotherapy

Chemotherapeutic efficacy can be greatly improved by developing nanoparticulate drug delivery systems (nano-DDS) with high drug loading capacity and smart stimulus-triggered drug release in tumor cells. Herein, we report a novel redox dual-responsive prodrug-nanosystem self-assembled by hydrophobic small-molecule conjugates of paclitaxel (PTX) and oleic acid (OA). Thioether linked conjugates (PTX-S-OA) and dithioether inserted conjugates (PTX-2S-OA) are designed to respond to the redox-heterogeneity in tumor. Dithioether has been reported to show redox dual-responsiveness, but we find that PTX-S-OA exhibits superior redox sensitivity over PTX-2S-OA, achieving more rapid and selective release of free PTX from the prodrug nanoassemblies triggered by redox stimuli. PEGylated PTX-S-OA nanoassemblies, with impressively high drug loading (57.4%), exhibit potent antitumor activity in a human epidermoid carcinoma xenograft. This novel prodrug-nanosystem addresses concerns related to the low drug loading and inefficient drug release from hydrophobic prodrugs of PTX, and provides possibilities for the development of redox dual-sensitive conjugates or polymers for efficient anticancer drug delivery.

The targeting mechanism of DHA ligand and its conjugate with Gemcitabine for the enhanced tumor therapy

Docosahexaenoic acid (DHA), an omega-3 C22 natural fatty acid serving as a precursor for metabolic and biochemical pathways, was reported as a targeting ligand of anticancer drugs. However, its tumor targeting ability and mechanism has not been claimed. Here we hypothesized that the uptake of DHA by tumor cells is related to the phosphatidylethanolamine (PE) contents in cell membranes. Thus, in this manuscript, the tumor-targeting ability of DHA was initially demonstrated in vitro and in vivo on different tumor cell lines by labeling DHA with fluorescence dyes. Subsequently, the tumor targeting ability was then correlated with the contents of PE in cell membranes to study the uptake mechanism. Further, DHA was conjugated with anticancer drug gemcitabine (DHA-GEM) for targeted tumor therapy. Our results demonstrated that DHA exhibited high tumor targeting ability and PE is the main mediator, which confirmed our hypothesis. The DHA-GEM displayed enhanced therapeutic efficacy than that of GEM itself, indicating that DHA is a promising ligand for tumor targeted therapy.

2'-Behenoyl-paclitaxel conjugate containing lipid nanoparticles for the treatment of metastatic breast cancer

The aim of these studies was to develop a novel 2'-behenoyl-paclitaxel (C22-PX) conjugate nanoparticle (NP) formulation for the treatment of metastatic breast cancer. A lipophilic paclitaxel derivative C22-PX was synthesized and incorporated into lipid-based NPs. Free C22-PX and its NP formulation were evaluated in a series of in vitro and in vivo studies. The results demonstrated that C22-PX NPs were much better tolerated and had significantly higher plasma and tumor AUCs compared to Taxol at the maximum tolerated dose (MTD) in a subcutaneous 4T1 mouse mammary carcinoma model. These benefits resulted in significantly improved antitumor efficacy with the NP-based formulation.

Clinical trials and progress with paclitaxel in ovarian cancer

Paclitaxel is a front-line agent for ovarian cancer chemotherapy, along with the platinum agents. Derived from the Pacific yew tree, Taxus brevifolia, paclitaxel has covered significant ground from the initial discovery of its antineoplastic properties to clinical applications in many forms of human cancers, including ovarian cancer. Although much has been published about the unique mechanism of action of this agent, several issues remain to be resolved. Finding the appropriate dosage schedule for paclitaxel in chemo-naïve and recurrent ovarian cancer, defining the role of paclitaxel in maintenance chemotherapy, and elucidating the mechanisms of taxane resistance are areas of intense research. Newer forms of taxanes are being manufactured to avoid troublesome adverse effects and to improve clinical efficacy. These issues are reviewed in detail in this paper with an emphasis on clinically relevant evidence-based information.

Synthesis and in vitro and in vivo evaluation of a series of dihydroisocoumarin derivatives conjugated with fatty acids, alcohols, and amines as potential anticancer agents

In this paper, we report the synthesis and biological activity of a series of dihydroisocoumarin analogues conjugated with fatty acids, alcohols, or amines, of varying hydrocarbon chain length and degree of unsaturation, to the dihydroisocoumarins, kigelin and mellein, at the C-7 and C-8 positions on the core dihydroisocoumarin structure. These compounds were evaluated for their antiproliferative activity against human breast cancer (MCF-7 and MDA-MB-468) and melanoma cells (SK-MEL-28 and Malme-3M) using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Two compounds conjugated with gamma-linolenyl alcohol (18:3 n-6) demonstrated potent antiproliferative activity in vitro with one of these 4-hydroxy-3-oxo-1,3-dihydro-isobenzofuran-5-carboxylic acid octadeca-6,9,12-trienyl ester, demonstrating significant antitumor activity in vivo in a number of human tumor xenograft models.

What is the role of novel taxanes in non-small-cell lung cancer?

The taxanes are among the most active cytotoxic agents in oncology and are widely used in adjuvant and advanced treatment settings in multiple tumor types. Paclitaxel and docetaxel are standard therapies in advanced non-small-cell lung cancer (NSCLC) and are increasingly used in earlier treatment settings. The taxanes are generally well tolerated but can be associated with severe, irreversible (and rarely life-threatening) toxicity. Premedication and special infusion sets are necessary to reduce the risk of hypersensitivity reactions. Newer taxanes are in development designed to improve the therapeutic index and ease of administration. Several agents have completed phase I/II clinical trials and are in phase III testing. Many other novel taxanes are at earlier stages of development and appear promising as single agents and in combination regimens. Safer and more effective taxanes could replace paclitaxel and docetaxel as standard treatments in NSCLC.

Paclitaxel: a review of adverse toxicities and novel delivery strategies

Better known as Taxol (Bristol-Myers Squibb), paclitaxel is the first member of the taxane family to be used in cancer chemotherapy. The taxanes exert their cytotoxic effect by arresting mitosis through microtubule stabilization, resulting in cellular apoptosis. The use of paclitaxel as a chemotherapeutic agent has become a broadly accepted option in the treatment of patients with ovarian, breast and non-small cell lung cancers, malignant brain tumors, and a variety of other solid tumors. However, significant toxicities, such as myelosuppression and peripheral neuropathy, limit the effectiveness of paclitaxel-based treatment regimens. This review addresses the toxicities associated with paclitaxel treatment and describes existing and future strategies of paclitaxel administration directed at limiting these toxicities.

Update on tubulin-binding agents

The clinical and commercial success of the taxanes and vinca alkaloids resulted in a drive to improve on current formulations and discover new compounds that target the microtubule. These strategies are all aimed at improving on (1) anti-tumour activity, (2) toxicity profile and (3) pharmacology. Drugs undergoing clinical development include the novel semi-synthetic taxane derivatives (DJ-927, XRP6258 and XRP9881), the epothilones, the dolastations, vinflunine and the combretastatin analogues. In several cases, some improvements in tumour response rates have been seen but randomised trials need to be completed before the role of specific novel tubulin-binding agents can be established.

Novel formulations of taxanes: a review. Old wine in a new bottle?

Over the past two decades, the taxanes have played a significant role in the treatment of various malignancies. However, the poor solubility of these compounds necessitates the inclusion of surfactant vehicles in their commercial formulations. Cremophor EL and polysorbate 80 have long comprised the standard solvent system for paclitaxel and docetaxel, respectively. A number of pharmacologic and biologic effects related to both of these drug formulations have been described, including clinically relevant acute hypersensitivity reactions and peripheral neuropathy. In addition, these solvents affect the disposition of intravenously administered solubilized drugs and leach plasticizers from polyvinylchloride infusion sets. A number of strategies to develop formulations of surfactant-free taxanes have been developed. They include albumin nanoparticles, polyglutamates, taxane analogs and prodrugs, emulsions, and lipsomes. An overview of these novel formulations of taxanes, their mechanisms of action, pharmacokinetics, dose and administration, adverse effects, and clinical efficacy will be discussed.

An introduction to dietary/supplemental omega-3 fatty acids for general health and prevention: Part II

The correction of a subtle nutritional deficiency that may reduce the risk of a future chronic disease is indeed a challenge. However, some specific examples in the past, such as the addition of folic acid to prevent neural tube defects and calcium and vitamin D to prevent osteoporosis, should provide some encouragement that some conditions can be prevented with the appropriate addition of a deficient compound. One of the most intriguing current and future impacts on public health may come from a higher intake of omega-3 fatty acids, such as alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). The omega-3 fatty acids continue to accumulate research that suggests that they may prevent a variety of diverse chronic diseases and potentially some acute clinical scenarios. In the first part of this article, the potential for these compounds to prevent certain cardiovascular conditions are discussed. In the second part, the potential for an impact in arthritis, numerous areas of cancer research, depression, maternal and child health, neurologic diseases, osteoporosis, and other medical disciplines are also briefly covered. The future appears bright for these agents, but specifically which conditions, who qualifies, testing, frequency, adequate sources, future trials, and numerous other questions need to be addressed and answered before the potential impact can catch up to the recent hype.