Substituted 4-hydroxy-1,2,3-triazoles: synthesis, characterization and first drug design applications through bioisosteric modulation and scaffold hopping approaches

The hydroxytriazole system is here analysed and used to modulate acidic moieties present in lead compounds.

New class of squalene-based releasable nanoassemblies of paclitaxel, podophyllotoxin, camptothecin and epothilone A

The present study reports the preparation of a novel class of squalene conjugates with paclitaxel, podophyllotoxin, camptothecin and epothilone A. The obtained compounds are characterized by a squalene tail that makes them able to self-assemble in water, and by a drug unit connected via a disulfide-containing linker to secure the release inside the cell. All the obtained compounds were effectively able to self-assemble and to release the parent drug in vitro. Disulfide-containing paclitaxel-squalene derivative showed a similar biological activity when compared to the free drug. Immunofluorescence assay shows that this squalene conjugate enters A549 cells and stain microtubule bundles. The results described herein pave the way for different classes of squalene-based releasable nanoassemblies.

Hyaluronic acid conjugates as vectors for the active targeting of drugs, genes and nanocomposites in cancer treatment

Hyaluronic acid (HA) is a naturally-occurring glycosaminoglycan and a major component of the extracellular matrix. Low levels of the hyaluronic acid receptor CD44 are found on the surface of epithelial, hematopoietic, and neuronal cells; it is overexpressed in many cancer cells, and in particular in tumor-initiating cells. HA has recently attracted considerable interest in the field of developing drug delivery systems, having been used, as such or encapsulated in different types of nanoassembly, as ligand to prepare nano-platforms for actively targeting drugs, genes, and diagnostic agents. This review describes recent progress made with the several chemical strategies adopted to synthesize conjugates and prepare novel delivery systems with improved behaviors.

Targeted treatment of folate receptor-positive platinum-resistant ovarian cancer and companion diagnostics, with specific focus on vintafolide and etarfolatide

Among the gynecological malignancies, ovarian cancer is the leading cause of mortality in developed countries. Treatment of ovarian cancer is based on surgery integrated with chemotherapy. Platinum-based drugs (cisplatin and carboplatin) comprise the core of first-line chemotherapy for patients with advanced ovarian cancer. Platinum-resistant ovarian cancer can be treated with cytotoxic chemotherapeutics such as paclitaxel, topotecan, PEGylated liposomal doxorubicin, or gemcitabine, but many patients eventually relapse on treatment. Targeted therapies based on agents specifically directed to overexpressed receptors, or to selected molecular targets, may be the future of clinical treatment. In this regard, overexpression of folate receptor-α on the surface of almost all epithelial ovarian cancers makes this receptor an excellent "tumor-associated antigen". With appropriate use of spacers/linkers, folate-targeted drugs can be distributed within the body, where they preferentially bind to ovarian cancer cells and are released inside their target cells. Here they can exert their desired cytotoxic function. Based on this strategy, 12 years after it was first described, a folate-targeted vinblastine derivative has now reached Phase III clinical trials in ovarian cancer. This review examines the importance of folate targeting, the state of the art of a vinblastine folate-targeted agent (vintafolide) for treating platinum-resistant ovarian cancer, and its diagnostic companion (etarfolatide) as a prognostic agent. Etarfolatide is a valuable noninvasive diagnostic imaging agent with which to select ovarian cancer patient populations that may benefit from this specific targeted therapy.

From Conventional to Stealth Liposomes: a New Frontier in Cancer Chemotherapy

In this review, the different types of liposome used in medicine, in particular in the field of antitumor therapy, are focalised, emphasizing their structures, pharmacological action, pharmacokinetics and biodistribution, toxicity profiles and in the main clinical applications. The first-generation liposomes (conventional liposomes) comprised a liposome-containing amphotericin B, Ambisome, and Myocet, doxorubicin-containing liposome used in clinical trials to treat metastatic breast cancer. The last generation liposomes were pegylated liposomal doxorubicin (Caelix), called "stealth liposomes" because of their ability to evade interception by the immune system, characterized by very long-circulation half-life, favourable pharmacokinetic behaviour and specific accumulation in tumor tissues.

Anticancer prodrugs: an overview of major strategies and recent developments

Research in anticancer chemotherapy has produced outstanding results, and mean survival rates have significantly improved over the last ten years. Nevertheless, all approved drugs are still characterized by narrow therapeutic windows that result mainly from their high systemic toxicity combined with their marked lack of tumor selectivity. Medicinal chemistry responds to the resulting demands with new analogues of a lead drug, or by developing prodrugs. Prodrugs are inactive compounds, which are metabolized in the body, either chemically or enzymatically, in a controlled or predictable manner, to the active parent drug. This review describes the results of strategies in prodrug development, subdivided into the principal categories of anticancer agents. The chemical implementation of prodrug approaches is illustrated through selected drug candidates.

Immunotoxins and anticancer drug conjugate assemblies: the role of the linkage between components

Immunotoxins and antibody-drug conjugates are protein-based drugs combining a target-specific binding domain with a cytotoxic domain. Such compounds are potentially therapeutic against diseases including cancer, and several clinical trials have shown encouraging results. Although the targeted elimination of malignant cells is an elegant concept, there are numerous practical challenges that limit conjugates’ therapeutic use, including inefficient cellular uptake, low cytotoxicity, and off-target effects. During the preparation of immunoconjugates by chemical synthesis, the choice of the hinge component joining the two building blocks is of paramount importance: the conjugate must remain stable in vivo but must afford efficient release of the toxic moiety when the target is reached. Vast efforts have been made, and the present article reviews strategies employed in developing immunoconjugates, focusing on the evolution of chemical linkers.

Squalene based nanocomposites: a new platform for the design of multifunctional pharmaceutical theragnostics

This study reports the design of a novel theragnostic nanomedicine which combines (i) the ability to target a prodrug of gemcitabine to an experimental solid tumor under the influence of a magnetic field with (ii) the imaging of the targeted tumoral nodule. This concept is based on the inclusion of magnetite nanocrystals into nanoparticles (NPs) constructed by self-assembling molecules of the squalenoyl gemcitabine (SQgem) bioconjugate. The nanocomposites are characterized by an unusually high drug loading, a significant magnetic susceptibility, and a low burst release. When injected to the L1210 subcutaneous mice tumor model, these magnetite/SQgem NPs were magnetically guided, and they displayed considerably greater anticancer activity than the other anticancer treatments (magnetite/SQgem NPs nonmagnetically guided, SQgem NPs, or gemcitabine free in solution). The histology and immunohistochemistry investigation of the tumor biopsies clearly evidenced the therapeutic superiority of the magnetically guided nanocomposites, while Prussian blue staining confirmed their accumulation at the tumor periphery. The superior therapeutic activity and enhanced tumor accumulation has been successfully visualized using T(2)-weighted imaging in magnetic resonance imaging (MRI). This concept was further enlarged by (i) the design of squalene-based NPs containing the T(1) Gd(3+) contrast agent instead of magnetite and (ii) the application to other anticancer squalenoyls, such as, cisplatin, doxorubicin, and paclitaxel. Thus, by combining different anticancer medicines as well as contrast imaging agents in NPs, we open the door toward generic conceptual framework for cancer treatment and diagnosis. This new theragnostic nanotechnology platform is expected to have important applications in cancer therapy.

Preparation of poly(MePEGCA-co-HDCA) nanoparticles with confined impinging jets reactor: experimental and modeling study

In this work, the biodegradable copolymer poly(methoxypolyethyleneglycolcyanoacrylate-co-hexadecylcyanoacrylate) is used to prepare nanoparticles via solvent displacement in a confined impinging jets reactor (CIJR). For comparison, nanoparticles constituted by the homopolymer counterpart are also investigated. The CIJR is a small passive mixer in which very fast turbulent mixing of the solvent (i.e., acetone and tetrahydrofuran) and of the antisolvent (i.e., water) solutions occurs under controlled conditions. The effect of the initial copolymer concentration, solvent type, antisolvent-to-solvent ratio, and mixing rate inside the mixer on the final nanoparticle size distribution, surface properties, and morphology is investigated from the experimental point of view. The effect of some of these parameters is studied by means of a computational fluid dynamics (CFD) model, capable of quantifying the mixing conditions inside the CIJR. Results show that the CIJR can be profitably used for producing nanoparticles with controlled characteristics, that there is a clear correlation between the mixing rate calculated by CFD and the mean nanoparticle size, and therefore that CFD can be used to design, optimize, and scale-up these processes.

EC-145, a folate-targeted Vinca alkaloid conjugate for the potential treatment of folate receptor-expressing cancers

EC-145, under development by Endocyte, is a conjugate composed of desacetylvinblastine monohydrazide linked through a peptide spacer to the targeting moiety folic acid, for the potential intravenous treatment of folate receptor-overexpressing tumors, in particular ovarian and lung cancers. In vitro studies demonstrated that EC-145 selectively binds to cells that overexpress the folate receptor, causing dose-dependent cytotoxicity. Furthermore, coincubation of the KB human nasopharyngeal carcinoma cell line with EC-145 and doxorubicin resulted in synergistic antitumor activity. Experiments in mouse tumor xenograft models have confirmed the potency of EC-145 and the curative effects of the drug conjugate were demonstrated in an aggressive lymphoma xenograft model. In a phase I clinical trial in patients with advanced or metastatic solid tumors, adverse events were generally of moderate severity with the most frequent being fatigue, constipation and peripheral sensory neuropathy. Preliminary data from a phase II clinical trial in patients with advanced ovarian cancer demonstrated that third- or fourth-line treatment with EC-145 yielded better disease control than second- or third-line liposomal doxorubicin. Coadministration of EC-145 and liposomal doxorubicin produced a statistically significant increase in progression-free survival over standard therapy in patients with platinum-resistant ovarian cancer. Phase III clinical trials are expected to confirm these promising results.

Chemical conjugation of ΔF508-CFTR corrector deoxyspergualin to transporter human serum albumin enhances its ability to rescue Cl−channel functions

The most common mutation of the cystic fibrosis (CF) gene, the deletion of Phe508, encodes a protein (ΔF508-CFTR) that fails to fold properly, thus mutated ΔF508-cystic fibrosis transmembrane conductance regulator (CFTR) is recognized and degraded via the ubiquitin-proteasome endoplasmic reticulum-associated degradation pathway. Chemical and pharmacological chaperones and ligand-induced transport open options for designing specific drugs to control protein (mis)folding or transport. A class of compounds that has been proposed as having potential utility in ΔF508-CFTR is that which targets the molecular chaperone and proteasome systems. In this study, we have selected deoxyspergualin (DSG) as a reference molecule for this class of compounds and for ease of cross-linking to human serum albumin (HSA) as a protein transporter. Chemical cross-linking of DSG to HSA via a disulfide-based cross-linker and its administration to cells carrying ΔF508-CFTR resulted in a greater enhancement of ΔF508-CFTR function than when free DSG was used. Function of the selenium-dependent oxidoreductase system was required to allow intracellular activation of HSA-DSG conjugates. The principle that carrier proteins can deliver pharmacological chaperones to cells leading to correction of defective CFTR functions is therefore proven and warrants further investigations.

Paclitaxel and pegylated liposomal doxorubicin in recurrent head and neck cancer: clinical and unexpected pharmacokinetic interactions

BACKGROUND

The combination of paclitaxel (PTX) with pegylated liposomal doxorubicin (PLD) is an interesting treatment for recurrent head and neck cancer. The pharmacokinetic behavior may depend on the interval between the intravenous administration of the two drugs. This study evaluates the clinical efficacy, toxicity and any possible interval-dependent pharmacokinetic interactions.

PATIENTS AND METHODS

Thirty patients were randomized to receive 80 mg/m2 PTX weekly and 12.5 mg/m2 PLD every two weeks at administration intervals of 0, 1, 3, 12 or 24 hours. Blood sampling was performed at day 1 and 15 and pharmacokinetics of PTX, PLD and Cremophor EL were evaluated by non-compartmental analysis.

RESULTS

Neutropenia was the most frequent side-effect (100% of patients; 30% grade 3-4). Hand-foot syndrome was severe in only 3% of patients. Overall response rate was 30%, with 3% complete responses and 27% partial responses. Stable disease and progression were 43% and 27%, respectively. Median response duration and overall median survival were 5.5 and 10 months respectively. Co-administration of PLD markedly reduced Cmax and the area under the curve (AUC), and increased PTX clearance. The differences in the PTX AUC and clearance between the 0 h and the 24 h experimental arms were statistically significant.

CONCLUSION

The PTX/PLD combination plays a palliative role (clinical benefit in 73% of patients) and has good tolerability. The PTX pharmacokinetic profile was unexpectedly affected by different administration time intervals; in the 0 h arm the AUC was reduced to one fourth, therefore a schedule with PTX on day one, PLD on day two may be preferred.

Stealth liposomes: review of the basic science, rationale, and clinical applications, existing and potential

Among several promising new drug-delivery systems, liposomes represent an advanced technology to deliver active molecules to the site of action, and at present several formulations are in clinical use. Research on liposome technology has progressed from conventional vesicles ("first-generation liposomes") to "second-generation liposomes", in which long-circulating liposomes are obtained by modulating the lipid composition, size, and charge of the vesicle. Liposomes with modified surfaces have also been developed using several molecules, such as glycolipids or sialic acid. A significant step in the development of long-circulating liposomes came with inclusion of the synthetic polymer poly-(ethylene glycol) (PEG) in liposome composition. The presence of PEG on the surface of the liposomal carrier has been shown to extend blood-circulation time while reducing mononuclear phagocyte system uptake (stealth liposomes). This technology has resulted in a large number of liposome formulations encapsulating active molecules, with high target efficiency and activity. Further, by synthetic modification of the terminal PEG molecule, stealth liposomes can be actively targeted with monoclonal antibodies or ligands. This review focuses on stealth technology and summarizes pre-clinical and clinical data relating to the principal liposome formulations; it also discusses emerging trends of this promising technology.