A phase I trial to evaluate the safety and pharmacokinetics of low-dose methotrexate as an anti-malarial drug in Kenyan adult healthy volunteers

Recent advances, challenges and updates on the development of therapeutics for malaria

Malaria has developed as a serious worldwide health issue as a result of the introduction of resistant Plasmodium species strains. Because of the common chemo resistance to most of the existing drugs on the market, it poses a severe health problem and significant obstacles in drug research. Malaria treatment has evolved during the last two decades in response to Plasmodium falciparum drug sensitivity and a return of the disease in tropical areas. Plasmodium falciparum is now highly resistant to the majority of antimalarial drugs. The parasite resistance drew focus to developing novel antimalarials to combat parasite resistance. The requirement for many novel antimalarial drugs in the future year necessitates adopting various drug development methodologies. Different innovative strategies for discovering antimalarial drugs are now being examined here. This review is primarily concerned with the description of newly synthesized antimalarial compounds, i.e. Tafenoquine, Cipargamin, Ferroquine, Artefenomel, DSM265, MMV390048 designed to improve the activity of pure antimalarial enantiomers. In this review, we selected the representative malarial drugs in clinical trials, classified them with detailed targets according to their action, discussed the relationship within the human trials, and generated a summative discussion with prospective expectations.

Antiprotozoal agents: How have they changed over a decade?

Neglected tropical diseases are a diverse group of communicable diseases that are endemic in low- or low-to-middle-income countries located in tropical and subtropical zones. The number and availability of drugs for treating these diseases are low, the administration route is inconvenient in some cases, and most of them have safety, efficacy, or adverse/toxic reaction issues. The need for developing new drugs to deal with these issues is clear, but one of the most drastic consequences of this negligence is the lack of interest in the research and development of new therapeutic options among major pharmaceutical companies. Positive changes have been achieved over the last few years, although the overall situation remains alarming. After more than one decade since the original work reviewing antiprotozoal agents came to light, now it is time to question ourselves: How has the scenario for the treatment of protozoal diseases such as malaria, leishmaniasis, human African trypanosomiasis, and American trypanosomiasis changed? This review covers the last decade in terms of the drugs currently available for the treatment of these diseases as well as the clinical candidates being currently investigated.

Cancer Clinical Trials in Africa-An Untapped Opportunity: Recommendations From AORTIC 2019 Conference Special Interest Group in Clinical Trials

Cancer is now a formidable health care burden in sub-Saharan Africa (SSA) due to lifestyle westernization and longer life expectancy. The exponential increase in cancer incidence coupled with high mortality rate is not comparable with that seen in westernized countries. To address global cancer disparity, globalization of cancer clinical trials to involve sub-Saharan Africa can serve as a platform where innovative targeted therapies can be made available to patients in the environ. In the 2019 African Organization for Research and Training in Cancer (AORTIC) conference held at Maputo, Mozambique, a group of clinical trialists spanning across multiple continents highlighted the opportunities in Africa for the conduct of cancer clinical trials. The secondary purpose of the meeting was to address the belief that Africa was incapable of conducting interventional cancer trials but showed the in-continent strengths, such as available capacities, trained local clinical trialists with clinical trial experiences, clinical trial consortia, local capabilities, mapping out logistics, ethical consideration, political will, real-time benefits of clinical trials to clinical practice, and future directions for trials.

Opportunistic tropical infections in immunosuppressed patients

Autoimmune and autoinflammatory diseases are associated with severe morbidity, and represent an impactful health and economic burden worldwide. The treatment of these diseases can include a course with detrimental side effects. Immunosuppression increases the risk of opportunistic infections, but in some cases, the abrupt discontinuation of these medications can result in immune reconstitution inflammatory syndrome. Special attention must be directed to endemic tropical infections, such as leishmaniasis, Chagas disease, malaria, arbovirosis, yellow fever, leprosy, paracoccidioidomycosis, disseminated strongyloidiasis, and ectoparasitosis. These endemic diseases of developing countries can be considered as possible emerging diseases in developed regions partially because of environmental factors and migration. In the present article, we aim to review the evidence-based aspects of the most important opportunistic tropical infections in immunosuppressed patients. We also aim to review the important aspects of vaccination, chemical prophylaxis, and treatment for these infections in people with medication-induced immunosuppression.

In vitro transport of methotrexate by Drosophila Multidrug Resistance-associated Protein

Methotrexate (MTX) is a widely used chemotherapeutic agent, immune suppressant and antimalarial drug. It is a substrate of several human ABC proteins that confer multidrug resistance to cancer cells and determine compartmentalization of a wide range of physiological metabolites and endo or xenobiotics, by their primary active transport across biological membranes. The substrate specificity and tissue distribution of these promiscuous human ABC transporters show a high degree of redundancy, providing robustness to these key physiological and pharmacological processes, such as the elimination of toxins, e.g. methotrexate from the body. A similar network of proteins capable of transporting methotrexate has been recently suggested to exist in Drosophila melanogaster. One of the key players of this putative network is Drosophila Multidrug-resistance Associated Protein (DMRP). DMRP has been shown to be a highly active and promiscuous ABC transporter, capable of transporting various organic anions. Here we provide the first direct evidence that DMRP, expressed alone in a heterologous system lacking other, potentially functionally overlapping D. melanogaster organic anion transporters, is indeed able to transport methotrexate. Our in vitro results support the hypothesized but debated role of DMRP in in vivo methotrexate excretion.

Consent for participating in clinical trials - Is it really informed?

The article explores the challenges of ensuring voluntary and informed consent which is obtained from potential research subjects in the north-eastern part of Romania. This study is one of the first empirical papers of this nature in Romania. The study used a quantitative survey design using the adapted Quality of Informed Consent (QuIC) questionnaire. The target population consisted of 100 adult persons who voluntarily enrolled in clinical trials. The informed consent form must contain details regarding the potential risks and benefits, the aim of the clinical trial, study design, confidentiality, insurance and contact details in case of additional questions. Our study confirmed that although all required information was included in the ICF, few clinical trial participants truly understood it. We also found that the most important predictive factor for a good subjective and objective understanding of the clinical trial was the level of education. Our study suggests that researchers should consider putting more effort in order to help clinical trials participants achieve a better understanding of the informed consent. In this way they will ensure that participants' decision-making is meaningful and that their interests are protected.

Anti-malarials are anti-cancers and vice versa - one arrow two sparrows

Repurposing is the novel means of drug discovery in modern science due to its affordability, safety and availability. Here, we systematically discussed the efficacy and mode of action of multiple bioactive, synthetic compounds and their potential derivatives which are used to treat/prevent malaria and cancer. We have also discussed the detailed molecular pathway involved in anti-cancer potentiality of an anti-malarial drug and vice versa. Although the causative agents, pathophysiology and manifestation of both the diseases are different but special emphasis has been given on similar pathways governing disease manifestation and the drugs which act through deregulating those pathways. Finally, a future direction has been speculated to combat these two diseases by a single agent developed using nanotechnology. Extended combination and new formulation of existing drugs for one disease may lead to the discovery of drug for other diseases like an arrow for two sparrows.

Health providers' perceptions of clinical trials: lessons from Ghana, Kenya and Burkina Faso

BACKGROUND

Clinical trials conducted in Africa often require substantial investments to support trial centres and public health facilities. Trial resources could potentially generate benefits for routine health service delivery but may have unintended consequences. Strengthening ethical practice requires understanding the potential effects of trial inputs on the perceptions and practices of routine health care providers. This study explores the influence of malaria vaccine trials on health service delivery in Ghana, Kenya and Burkina Faso.

METHODS

We conducted: audits of trial inputs in 10 trial facilities and among 144 health workers; individual interviews with frontline providers (n=99) and health managers (n=14); and group discussions with fieldworkers (n=9 discussions). Descriptive summaries were generated from audit data. Qualitative data were analysed using a framework approach.

RESULTS

Facilities involved in trials benefited from infrastructure and equipment upgrades, support with essential drugs, access to trial vehicles, and placement of additional qualified trial staff. Qualified trial staff in facilities were often seen as role models by their colleagues; assisting with supportive supervision and reducing facility workload. Some facility staff in place before the trial also received formal training and salary top-ups from the trials. However, differential access to support caused dissatisfaction, and some interviewees expressed concerns about what would happen at the end of the trial once financial and supervisory support was removed.

CONCLUSION

Clinical trials function as short-term complex health service delivery interventions in the facilities in which they are based. They have the potential to both benefit facilities, staff and communities through providing the supportive environment required for improvements in routine care, but they can also generate dissatisfaction, relationship challenges and demoralisation among staff. Minimising trial related harm and maximising benefits requires careful planning and engagement of key actors at the outset of trials, throughout the trial and on its' completion.

Experience of using an open source clinical trials data management software system in Kenya

BACKGROUND

Clinical trials data management (CTDM) remains one of the many challenges in running state of the art trials in resource-poor settings since most trials do not allocate, or have available, sufficient resources for CTDM and because of poor internet connectivity. Open-source software like OpenClinica could be a solution in such scenarios.

FINDINGS

In 2007, the KEMRI-Wellcome Trust Research Programme (KWTRP) adopted OpenClinica (OC) community edition, an open-source software system and we share our experience and lessons learnt since its adoption. We have used OC in three different modes; direct remote data entry from sites through Global System for Mobile Communications (GSM) modems, a centralized data centre approach where all data from paper records were entered at a central location and an off-line approach where data entry was done from a copy of database hosted on a field-site server laptop, then data uploaded to a centralized server later. We have used OC in eleven trials/studies with a cumulative number of participants in excess of 6000. These include large and complex trials, with multiple sites recruiting in different regions of East Africa. In the process, we have developed substantial local capacity through hands-on training and mentorship, which we have now begun to share with other institutions in the region.

CONCLUSIONS

Our experience demonstrates that an open source data management system to manage trials' data can be utilized to international industry standards in resource-poor countries.

Repositioning: the fast track to new anti-malarial medicines?

BACKGROUND

Repositioning of existing drugs has been suggested as a fast track for developing new anti-malarial agents. The compound libraries of GlaxoSmithKline (GSK), Pfizer and AstraZeneca (AZ) comprising drugs that have undergone clinical studies in other therapeutic areas, but not achieved approval, and a set of US Food and Drug Administration (FDA)-approved drugs and other bio-actives were tested against Plasmodium falciparum blood stages.

METHODS

Molecules were tested initially against erythrocytic co-cultures of P. falciparum to measure proliferation inhibition using one of the following methods: SYBR®I dye DNA staining assay (3D7, K1 or NF54 strains); [(3)H] hypoxanthine radioisotope incorporation assay (3D7 and 3D7A strain); or 4',6-diamidino-2-phenylindole (DAPI) DNA imaging assay (3D7 and Dd2 strains). After review of the available clinical pharmacokinetic and safety data, selected compounds with low μM activity and a suitable clinical profile were tested in vivo either in a Plasmodium berghei four-day test or in the P. falciparum Pf3D7(0087/N9) huSCID 'humanized' mouse model.

RESULTS

Of the compounds included in the GSK and Pfizer sets, 3.8% (9/238) had relevant in vitro anti-malarial activity while 6/100 compounds from the AZ candidate drug library were active. In comparison, around 0.6% (24/3,800) of the FDA-approved drugs and other bio-actives were active. After evaluation of available clinical data, four investigational drugs, active in vitro were tested in the P. falciparum humanized mouse model: UK-112,214 (PAF-H1 inhibitor), CEP-701 (protein kinase inhibitor), CEP-1347 (protein kinase inhibitor), and PSC-833 (p-glycoprotein inhibitor). Only UK-112,214 showed significant efficacy against P. falciparum in vivo, although at high doses (ED90 131.3 mg/kg [95% CI 112.3, 156.7]), and parasitaemia was still present 96 hours after treatment commencement. Of the six actives from the AZ library, two compounds (AZ-1 and AZ-3) were marginally efficacious in vivo in a P. berghei model.

CONCLUSIONS

Repositioning of existing therapeutics in malaria is an attractive proposal. Compounds active in vitro at μM concentrations were identified. However, therapeutic concentrations may not be effectively achieved in mice or humans because of poor bio-availability and/or safety concerns. Stringent safety requirements for anti-malarial drugs, given their widespread use in children, make this a challenging area in which to reposition therapy.

Preclinical drug evaluation system in the Plasmodium knowlesi baboon model of malaria: the methotrexate study

BACKGROUND

Drug resistance against first-line antimalarials warrants search for new lead compounds and repurposing of drugs such as methotrexate. Animal models are required for preclinical drug development before clinical testing. This study aimed to develop a preclinical drug development system in baboons infected with Plasmodium knowlesi.

METHODS

Protocols for drug administration, pharmacokinetics, clinical chemistry and haematology were developed in the baboon model. Baboons were infected with P. knowlesi and methotrexate administered orally for 5 days. Clinical signs, parasitaemia, gross and histopathology examinations were conducted to determine effect of methotrexate in baboons.

RESULTS

No major clinical chemistry, haematology and pathological changes attributable to methotrexate were observed. Parasitaemia suppression of 77.67% was achieved at a methotrexate dose of 3.0 mg/kg.

CONCLUSIONS

A protocol for preclinical drug development in the baboon was optimized. Methotrexate suppressed P. knowlesi malaria in baboons. These findings warrant further characterization of methotrexate for use in combination therapy.

Plasmodium drug targets outside the genetic control of the parasite

Drug development often seeks to find "magic bullets" which target microbiologic proteins while not affecting host proteins. Paul Ehrlich tested methylene blue as an antimalarial but this dye was not superior to quinine. Many successful antimalarial therapies are "magic shotguns" which target many Plasmodium pathways with little interference in host metabolism. Two malaria drug classes, the 8- aminoquinolines and the artemisinins interact with cytochrome P450s and host iron protoporphyrin IX or iron, respectively, to generate toxic metabolites and/or radicals, which kill the parasite by interference with many proteins. The non 8-amino antimalarial quinolines like quinine or piperaquine bind heme to inhibit the process of heme crystallization, which results in multiple enzyme inhibition and membrane dysfunction. The quinolines and artemisinins are rapidly parasiticidal in contrast to metal chelators, which have a slower parasite clearance rate with higher drug concentrations. Iron chelators interfere with the artemisinins but otherwise represent a strategy of targeting multiple enzymes containing iron. Interest has been revived in antineoplastic drugs that target DNA metabolism as antimalarials. Specific drug targeting or investigation of the innate immunity directed to the more permeable trophozoite or schizont infected erythrocyte membrane has been under explored. Novel drug classes in the antimalarial development pipeline which either target multiple proteins or unchangeable cellular targets will slow the pace of drug resistance acquisition.

Drug repositioning in the treatment of malaria and TB

The emergence and spread of drug resistance in the malaria parasite Plasmodium falciparum as well as multi- and extremely drug-resistant forms of Mycobacterium tuberculosis, the causative agent of TB, could hamper the control of these diseases. For instance, there are indications that the malaria parasite is becoming resistant to artemisinin derivatives, drugs that form the backbone of antimalarial combination therapy. Likewise, Mycobacterium tuberculosis strains that are multidrug-resistant or extremely drug-resistant to first- and second-line drugs have been associated with increased mortality. Thus, more than ever, new antimalarials and anti-TB drugs are needed. One of the strategies to discover new drugs is to reposition or repurpose existing drugs, thus reducing the cost and time of drug development. In this review, we discuss how this concept has been used in the past to discover antimalarial and anti-TB drugs, and summarize strategies that can lead to the discovery and development of new drugs.