Cancer pharmacotherapy: 21st century 'magic bullets' and changing paradigms

Ellagic Acid and Schisandrins: Natural Biaryl Polyphenols with Therapeutic Potential to Overcome Multidrug Resistance in Cancer

Multidrug resistance (MDR) is one of the major clinical challenges in cancer treatment and compromises the effectiveness of conventional anticancer chemotherapeutics. Among known mechanisms of drug resistance, drug efflux via ATP binding cassette (ABC) transporters, namely P-glycoprotein (P-gp) has been characterized as a major mechanism of MDR. The primary function of ABC transporters is to regulate the transport of endogenous and exogenous small molecules across the membrane barrier in various tissues. P-gp and similar efflux pumps are associated with MDR because of their overexpression in many cancer types. One of the intensively studied approaches to overcome this mode of MDR involves development of small molecules to modulate P-gp activity. This strategy improves the sensitivity of cancer cells to anticancer drugs that are otherwise ineffective. Although multiple generations of P-gp inhibitors have been identified to date, reported compounds have demonstrated low clinical efficacy and adverse effects. More recently, natural polyphenols have emerged as a promising class of compounds to address P-gp linked MDR. This review highlights the chemical structure and anticancer activities of selected members of a structurally unique class of 'biaryl' polyphenols. The discussion focuses on the anticancer properties of ellagic acid, ellagic acid derivatives, and schisandrins. Research reports regarding their inherent anticancer activities and their ability to sensitize MDR cell lines towards conventional anticancer drugs are highlighted here. Additionally, a brief discussion about the axial chirality (i.e., atropisomerism) that may be introduced into these natural products for medicinal chemistry studies is also provided.

Tumor-associated macrophages: Role in the pathological process of tumorigenesis and prospective therapeutic use (Review)

The aim of the present study was to evaluate the current body of knowledge regarding tumor-associated macrophages (TAMs) and their potential use in antitumor therapy, based on their role in the pathological process of tumorigenesis. For this purpose, a critical analysis of published data and summarization of the findings available from original studies, focusing on the role of TAMs in the pathological process, and their potential therapeutic application was performed. Promising key avenues of research were identified in this field. The following issues seem the most promising and thus worth further investigation: i) The process of M1/M2 macrophage polarization, macrophage characteristics at intermediate polarization steps and their role in the tumor process; ii) determining the conditions necessary for transitions between the M1 and M2 macrophage phenotypes and the role of signals from the microenvironment in this process; iii) cause-and-effect associations between the quantity and quality of macrophages, and the prognosis and outcome of the pathological process; iv) modulation of macrophages and stimulation of their phagocytic activity with drugs; v) targeted vector-based systems for drug delivery to macrophages; and vi) targeted drug delivery systems with macrophages as carriers, thus potentially combining chemotherapy and immunotherapy.

Increasing the Potential of the Auristatin Cancer-Drug Family by Shifting the Conformational Equilibrium

Monomethyl auristatin E and monomethyl auristatin F are widely used cytotoxic agents in antibody–drug conjugates (ADCs), a group of promising cancer drugs. The ADCs specifically target cancer cells, releasing the auristatins inside, which results in the prevention of mitosis. The auristatins suffer from a potentially serious flaw, however. In solution, the molecules exist in an equal mixture of two conformers, cis and trans. Only the trans-isomer is biologically active and the isomerization process, i.e., the conversion of cis to trans is slow. This significantly diminishes the efficiency of the drugs and their corresponding ADCs, and perhaps more importantly, raises concerns over drug safety. The potency of the auristatins would be enhanced by decreasing the amount of the biologically inactive isomer, either by stabilizing the trans-isomer or destabilizing the cis-isomer. Here, we follow the computer-aided design strategy of shifting the conformational equilibrium and employ high-level quantum chemical modeling to identify promising candidates for improved auristatins. Coupled cluster calculations predict that a simple halogenation in the norephedrine/phenylalanine residues shifts the isomer equilibrium almost completely toward the active trans-conformation, due to enhanced intramolecular interactions specific to the active isomer.

Access to innovative cancer medicines in a middle-income country - the case of Mexico

BACKGROUND

Cancer has become the third cause of death in Mexico. Treatment for cancer is often complex and lengthy. New and better medicines enter the market at high prices, which may limit access. Like most Latin American countries, Mexico has an essential cancer medicines list that includes innovative medicines. Their accessibility and use in the public sector remains unknown. Therefore, we describe the use, as a proxy of access, of innovative and essential cancer medicines in the public sector in Mexico, by insurance institution, and by five regions between 2010 to 2016.

METHODS

We used drug utilization research methods to assess the use of eight patented cancer medicines. Through the national transparency platform, we obtained data on the quantities of these medicines used in all public health facilities and social health insurance institutions and recalculated those figures into defined daily dose (DDD) per 1000 population per year.

RESULTS

Overall, the use of all medicines increased over the years, especially for trastuzumab, rituximab and imatinib. The use of innovative medicines was higher per population covered in social health insurance institutions than in governmental facilities. Throughout the study period, the Central region (including Mexico City) has used more medicines per population than the other regions.

CONCLUSIONS

The use and access of some essential innovative cancer medicines has increased over the years, but remains unequal across insurance schemes and regions. Particularly, the Ministry of Health Insurance scheme and Northern and Western regions in the country would benefit from additional efforts to increase access to essential cancer medicines.

New insight on the structural features of the cytotoxic auristatins MMAE and MMAF revealed by combined NMR spectroscopy and quantum chemical modelling

Antibody-drug conjugates (ADCs) are emerging as a promising class of selective drug delivery systems in the battle against cancer and other diseases. The auristatins monomethyl auristatin E (MMAE) and monomethyl auristatin F (MMAF) appear as the cytotoxic drug in almost half of the state-of-the-art ADCs on the market or in late stage clinical trials. Here, we present the first complete NMR spectroscopic characterisation of these challenging molecules, and investigate their structural properties by a combined NMR and quantum chemical modelling approach. We find that in solution, half of the drug molecules are locked in an inactive conformation, severely decreasing their efficiency, and potentially increasing the risk of side-effects. Furthermore, we identify sites susceptible to future modification, in order to potentially improve the performance of these drugs.

Nanomedicine for prostate cancer using nanoemulsion: A review

Prostate cancer (PCa) is a worldwide issue, with burgeoning rise in prevalence, morbidity and mortality. Targeted drug delivery, a long sort solution in this regard using controlled release (CR) - nanocarriers, is still a challenge. There is an emerging criticism that, the challenges are due to less appreciation for the biological barriers and lack of corresponding newer technologies. Over the years, more understanding about the biological barriers has come with the progress in characterization techniques. Correspondingly, there is a change in opinion about approaches in clinical trial that; focus of the end point need to be shifted towards disease stabilization for these explorative technologies. Currently, there is a requirement to overcome these newly identified challenges to develop newer affordable therapeutics. The ongoing clinical protocol for therapy using CR-nanocarriers is intravenous injection followed by local targeting to cancer site. This is the most accepted protocol and new CR-nanocarriers are being developed to suit this protocol. In this review, recent progress in treatment of PCa using CR-nanocarriers is analyzed with respect to newly identified biological barriers and design challenges. Possibilities of exploring nanoemulsion (NE) platform for targeted drug delivery to PCa are examined. Repurposing of drugs and combination therapy using NE platform targeted to PCa can be explored for design and development of affordable nanomedicine. In 20yrs. from now there expected to be numerous affordable nanomedicine technologies available in market exploring these lines.

What do clinical pharmacologists do? A questionnaire survey of senior UK clinical pharmacologists

Since the discipline expanded during 1970-1990, the number of UK consultant clinical pharmacologists has fallen. This paper describes the results of a questionnaire survey of the work patterns of 53 UK consultant clinical pharmacologists, including 35 (66%) employed by universities and 13 (25%) employed by the National Health Service (NHS). The range of activities undertaken includes: teaching medical students and others the principles of clinical pharmacology and practical therapeutics; research in a wide range of pharmacological and therapeutic areas; patient care, mostly in acute and general hospital medicine and in out-patient clinics; service both locally and nationally on a wide range of committees related to drug therapy; editorial work on learned journals and preparation of written teaching materials, including journal articles, didactic textbooks, reference books, and e-learning materials. The median amount of time that a UK consultant clinical pharmacologist spends on these activities is 50 hours per week; several work more than that. The time is spent as follows: teaching 10%; research 40%; clinical work 30%; policy and administration 12%; editorial work and writing 8%. The numbers of physicians who have been newly registered with the General Medical Council as clinical pharmacologists each year has so far been undiminished, but the number of consultant posts has fallen in 1990-2010. Many trainees therefore leave the discipline when they become consultants.

Design, synthesis, screening, and molecular modeling study of a new series of ROS1 receptor tyrosine kinase inhibitors

A series of rationally designed ROS1 tyrosine kinase inhibitors was synthesized and screened. Compound 12b has showed good potency with IC50 value of 209 nM, which is comparable with that of the reference lead compound 1. Molecular modeling studies have been performed, that is, a homology model for ROS1 was built, and the screened inhibitors were docked into its major identified binding site. The docked poses along with the activity data have revealed a group of the essential features for activity. Overall, simplification of the lead compound 1 into compound 12b has maintained the activity, while facilitated the synthetic advantages. A molecular interaction model for ROS1 kinase and inhibitors has been proposed.

Serum Uric Acid as a Prognostic Predictor in Pulmonary Arterial Hypertension With Connective Tissue Disease

BACKGROUND

Pulmonary arterial hypertension (PAH) has been identified as a life threatening complication of connective tissue disease. However, the association between serum uric acid (UA) levels and long-term outcome in PAH with connective tissue disease has not been evaluated. We therefore assessed whether serum UA levels are related to the mortality of such patients.

METHODS AND RESULTS

We investigated 90 consecutive patients with connective tissue disease who were initially diagnosed with PAH by echocardiography, and assessed the long-term clinical outcome in populations with higher (> or = 4.7 mg/dL) and lower serum UA levels. Kaplan-Meier analysis showed that patients with higher median serum UA values had a significantly worse survival rate for any cause of death (54.5% versus 84.7%, log-rank, P < 0.01) and PAH-related death (72.7% versus 93.4%, log-rank, P < 0.01) than those with low values. Multivariate analysis showed that an elevated serum UA level was an independent predictor for survival (hazard ratio, 1.88, 95% CI [1.24- 2.84], P < 0.01).

CONCLUSION

Elevated serum UA levels are associated with a poor prognosis and can serve as a prognostic predictor for patients with PAH secondary to connective tissue disease.