Pharmacokinetic profiles of artesunate following multiple intravenous doses of 2, 4, and 8 mg/kg in healthy volunteers: phase 1b study

Safety and pharmacokinetic properties of a new formulation of parenteral artesunate in healthy Thai volunteers

BACKGROUND

Parenteral artesunate is the first-line therapy for severe malaria. Artesunate, in its current formulation, must be prepared immediately before administration by first dissolving in sodium bicarbonate solution and then diluting in saline. A novel solvent for rapid and stable single step reconstitution of artesunate was recently developed showing improved solubility and stability. This study aimed to compare the safety and pharmacokinetic properties of the currently available and newly developed parenteral formulation of artesunate in healthy Thai volunteers.

METHODS

This was an open-label, randomized, 4 periods, 4-treatments, 24-sequence, single-dose, cross-over study in 72 male and female healthy Thai volunteers. Frequent pharmacokinetic samples were collected in all volunteers at each dose occasion. Observed concentration-time profiles were analysed with a non-compartmental approach followed by a bioequivalence evaluation.

RESULTS

Both intramuscular and intravenous administrations of the new parenteral formulation of artesunate were safe and well-tolerated, with no additional safety signals compared to the currently used formulation. The pharmacokinetic properties of artesunate and its active metabolite, dihydroartemisinin, were well-characterized, and showed rapid conversion of artesunate into dihydroartemisinin. Intramuscular administration of the newly formulated artesunate resulted in almost complete bioavailability of dihydroartemisinin. The pharmacokinetic properties were similar between the old and new formulation.

CONCLUSIONS

The new and more easily prepared formulation of artesunate was safe and well-tolerated, with similar pharmacokinetic properties compared to the currently used formulation. Dihydroartemisinin, the active metabolite responsible for the majority of the anti-malarial effect, showed equivalent exposure after both intravenous and intramuscular administration of artesunate, suggesting that both routes of administration should generate comparable therapeutic effects.

TRIAL REGISTRATION

The study was registered to clinicaltrials.gov (#TCTR20170907002).

Inter-Species Pharmacokinetic Modeling and Scaling for Drug Repurposing of Pyronaridine and Artesunate

Even though several new targets (mostly viral infection) for drug repurposing of pyronaridine and artesunate have recently emerged in vitro and in vivo, inter-species pharmacokinetic (PK) data that can extend nonclinical efficacy to humans has not been reported over 30 years of usage. Since extrapolation of animal PK data to those of humans is essential to predict clinical outcomes for drug repurposing, this study aimed to investigate inter-species PK differences in three animal species (hamster, rat, and dog) and to support clinical translation of a fixed-dose combination of pyronaridine and artesunate. PK parameters (e.g., steady-state volume of distribution (Vss), clearance (CL), area under the concentration-time curve (AUC), mean residence time (MRT), etc.) of pyronaridine, artesunate, and dihydroartemisinin (an active metabolite of artesunate) were determined by non-compartmental analysis. In addition, one- or two-compartment PK modeling was performed to support inter-species scaling. The PK models appropriately described the blood concentrations of pyronaridine, artesunate, and dihydroartemisinin in all animal species, and the estimated PK parameters in three species were integrated for inter-species allometric scaling to predict human PKs. The simple allometric equation (Y = a × Wb) well explained the relationship between PK parameters and the actual body weight of animal species. The results from the study could be used as a basis for drug repurposing and support determining the effective dosage regimen for new indications based on in vitro/in vivo efficacy data and predicted human PKs in initial clinical trials.

Safety and efficacy of artesunate treatment in severely injured patients with traumatic hemorrhage. The TOP-ART randomized clinical trial

PURPOSE

This study aimed at determining whether intravenous artesunate is safe and effective in reducing multiple organ dysfunction syndrome in trauma patients with major hemorrhage.

METHODS

TOP-ART, a randomized, blinded, placebo-controlled, phase IIa trial, was conducted at a London major trauma center in adult trauma patients who activated the major hemorrhage protocol. Participants received artesunate or placebo (2:1 randomization ratio) as an intravenous bolus dose (2.4 mg/kg or 4.8 mg/kg) within 4 h of injury. The safety outcome was the 28-day serious adverse event (SAE) rate. The primary efficacy outcome was the 48 h sequential organ failure assessment (SOFA) score. The per-protocol recruitment target was 105 patients.

RESULTS

The trial was terminated after enrolment of 90 patients because of safety concerns. Eighty-three participants received artesunate (n = 54) or placebo (n = 29) and formed the safety population and 75 met per-protocol criteria (48 artesunate, 27 placebo). Admission characteristics were similar between groups (overall 88% male, median age 29 years, median injury severity score 22), except participants who received artesunate were more shocked (median base deficit 9 vs. 4.7, p = 0.042). SAEs occurred in 17 artesunate participants (31%) vs. 5 who received placebo (17%). Venous thromboembolic events (VTE) occurred in 9 artesunate participants (17%) vs. 1 who received placebo (3%). Superiority of artesunate was not supported by the 48 h SOFA score (median 5.5 artesunate vs. 4 placebo, p = 0.303) or any of the trial's secondary endpoints.

CONCLUSION

Among critically ill trauma patients, artesunate is unlikely to improve organ dysfunction and might be associated with a higher VTE rate.

Artesunate: A review of its therapeutic insights in respiratory diseases

BACKGROUND

Artesunate, as a semi-synthetic artemisinin derivative of sesquiterpene lactone, is widely used in clinical antimalarial treatment due to its endoperoxide group. Recent studies have found that artesunate may have multiple pharmacological effects, indicating its significant therapeutic potential in multiple respiratory diseases.

PURPOSE

This review aims to summarize proven and potential therapeutic effects of artesunate in common respiratory disorders.

STUDY DESIGN

This review summarizes the pharmacological properties of artesunate and then interprets the function of artesunate in various respiratory diseases in detail, such as bronchial asthma, chronic obstructive pulmonary disease, lung injury, lung cancer, pulmonary fibrosis, coronavirus disease 2019, etc., on different target cells and receptors according to completed and ongoing in silico, in vitro, and in vivo studies (including clinical trials).

METHODS

Literature was searched in electronic databases, including Pubmed, Web of Science and CNKI with the primary keywords of 'artesunate', 'pharmacology', 'pharmacokinetics', 'respiratory disorders', 'lung', 'pulmonary', and secondary search terms of 'Artemisia annua L.', 'artemisinin', 'asthma', 'chronic obstructive lung disease', 'lung injury', 'lung cancer', 'pulmonary fibrosis', 'COVID-19' and 'virus' in English and Chinese. All experiments were included. Reviews and irrelevant studies to the therapeutic effects of artesunate on respiratory diseases were excluded. Information was sort out according to study design, subject, intervention, and outcome.

RESULTS

Artesunate is promising to treat multiple common respiratory disorders via various mechanisms, such as anti-inflammation, anti-oxidative stress, anti-hyperresponsiveness, anti-proliferation, airway remodeling reverse, induction of cell death, cell cycle arrest, etc. CONCLUSION: Artesunate has great potential to treat various respiratory diseases.

Dihydroartemisinin Exerts Antifibrotic and Anti-Inflammatory Effects in Graves' Ophthalmopathy by Targeting Orbital Fibroblasts

Graves' ophthalmopathy (GO) is a common orbital disease that threatens visual function and appearance. Orbital fibroblasts (OFs) are considered key target and effector cells in GO. In addition, hyaluronan (HA) production, inflammation, and orbital fibrosis are intimately linked to the pathogenesis of GO. In this study, we explored the therapeutic effects of dihydroartemisinin (DHA), an antimalarial drug, on GO-derived, primary OFs. CCK8 and EdU assays were applied to evaluate the antiproliferative effect of DHA on OFs. Wound healing assays were conducted to assess OF migration capacity, while qRT-PCR, western blotting, ELISA, and immunofluorescence were used to determine the expression of fibrosis-related and pro-inflammatory markers in these cells. Moreover, RNA sequencing was conducted to identify differentially expressed genes (DEGs) in DHA-treated OFs, and Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of DEGs was performed to explore potential mechanisms mediating the antifibrotic effect of DHA on GO-derived OFs. Results showed that DHA dose-dependently inhibited OF proliferation and downregulated, at the mRNA and protein levels, TGF-β1-induced expression of fibrosis markers, including alpha smooth muscle actin (α-SMA) and connective tissue growth factor (CTGF). Furthermore, DHA inhibited TGF-β1 induced phosphorylation of extracellular signal-regulated protein kinase 1/2 (ERK1/2) and signal transducer and activator of transcription 3 (STAT3), which suggested that DHA exerted antifibrotic effects via suppression of the ERK and STAT3 signaling pathways. In addition, DHA suppressed the expression of pro-inflammatory cytokines and chemokines, including IL-6, IL-8, CXCL-1, MCP-1, and ICAM-1, and attenuated HA production induced by IL-1β in GO-derived OFs. In conclusion, our study provides first-time evidence that DHA may significantly alleviate pathogenic manifestations of GO by inhibiting proliferation, fibrosis- and inflammation-related gene expression, and HA production in OFs. These data suggest that DHA may be a promising candidate drug for treatment of GO.

Predicting the Disposition of the Antimalarial Drug Artesunate and Its Active Metabolite Dihydroartemisinin Using Physiologically Based Pharmacokinetic Modeling

Artemisinin-based combination therapies (ACTs) have proven to be effective in helping to combat the global malaria epidemic. To optimally apply these drugs, information about their tissue-specific disposition is required, and one approach to predict these pharmacokinetic characteristics is physiologically based pharmacokinetic (PBPK) modeling. In this study, a whole-body PBPK model was developed to simulate the time-dependent tissue concentrations of artesunate (AS) and its active metabolite, dihydroartemisinin (DHA). The model was developed for both rats and humans and incorporated drug metabolism of the parent compound and major metabolite. Model calibration was conducted using data from the literature in a Bayesian framework, and model verification was assessed using separate sets of data. Results showed good agreement between model predictions and the validation data, demonstrating the capability of the model in predicting the blood, plasma, and tissue pharmacokinetics of AS and DHA. It is expected that such a tool will be useful in characterizing the disposition of these chemicals and ultimately improve dosing regimens by enabling a quantitative assessment of the tissue-specific drug levels critical in the evaluation of efficacy and toxicity.

Multiple modes of cell death in neuroendocrine tumors induced by artesunate

BACKGROUND

The paucity of effective treatment in neuroendocrine tumors (NETs) encouraged us to investigate the therapeutic value of artesunate (ART) promised by its inhibitory effect against various tumors and broad safety profile.

METHODS

We evaluated the impact of ART on three NET cell lines, BON-1, QGP-1 and NCI-H727 on cellular and molecular levels.

RESULTS

Our results showed that ART induced endoplasmic reticulum (ER) stress through phosphorylation of eIF2α, which further gave rise to autophagy in all three NET cell lines. Specifically, apoptosis and ferroptosis were also observed in BON-1 cells, which made BON-1 cell line more vulnerable upon ART treatment. The different sensitivities presented on the three cell lines also associated with a differential regulation of p21 on the long run. Co-treatment with p21 inhibitor UC2288 showed an additive effect on QGP-1 and NCI-H727 cell lines indicating p21 upregulation in these two cell lines might confer resistance towards ART treatment.

CONCLUSIONS

It is possible to include ART in the treatment of NETs in the future.

Artemisinin Derivatives Stimulate DR5-Specific TRAIL-Induced Apoptosis by Regulating Wildtype P53

Artemisinin derivatives, widely known as commercial anti-malaria drugs, may also have huge potential in treating cancer cells. It has been reported that artemisinin derivatives can overcome resistance to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis in liver and cervical cancer cells. In our study, we demonstrated that artesunate (ATS) and dihydroartemisinin (DHA) are more efficient in killing colon cancer cells compared to artemisinin (ART). ATS/DHA induces the expression of DR5 in a P53 dependent manner in HCT116 and DLD-1 cells. Both ATS and DHA overcome the resistance to DHER-induced apoptosis in HCT116, mainly through upregulating death receptor 5 (DR5). We also demonstrate that DHA sensitizes HCT116 cells to DHER-induced apoptosis via P53 regulated DR5 expression in P53 knockdown assays. Nevertheless, a lower effect was observed in DLD-1 cells, which has a single Ser241Phe mutation in the P53 DNA binding domain. Thus, the status of P53 could be one of the determinants of TRAIL resistance in some cancer cells. Finally, the combination treatment of DHA and the TRAIL variant DHER increases cell death in 3D colon cancer spheroid models, which shows its potential as a novel therapy.

Investigating the Comparative Effects of Six Artemisinin-based Combination Therapies on Plasmodium-induced Hepatorenal Toxicity

Background

Too many artemisinin-based combination therapies (ACTs) are available, thus creating a dilemma on the most preferred for the treatment of malaria.

Aim

We compared the effect of six ACTs in mitigating Plasmodium-induced hepatorenal toxicity in experimental malaria.

Materials and Methods

Forty adult male Swiss mice allotted into eight groups: Group 1 (normal control [NC] uninfected and untreated), Group 2 (parasitized nontreated - [PNT]), and Groups 3-8 received Plasmodium berghei inoculum. After 72 h, the initial parasitemia was established. Groups 3-8 were administered oral therapeutic doses of artesunate-amodiaquine (AA), artesunate-mefloquine (AM), artesunate-sulfadoxine-pyrimethamine (ASP), artemisinin-piperaquine (AP), dihydroartemisinin-piperaquine (DP), and artemether-lumefantrine (AL) per kg bodyweight, respectively, as standard regimen, and final parasitemia determined. Animals were euthanized via chloroform inhalation and blood collected for hepatorenal analysis. Liver and kidney were dissected out for histology.

Results

Parasitemia was significantly (P < 0.05) decreased in tests compared to PNT, except in ASP group. Liver enzymes were significantly (P < 0.05) increased in PNT compared to tests and NC. Hyperplastic cells and portal tract inflammation were prominent in ASP group, but mild to moderate in other treated groups. Urea-creatinine were significantly (P < 0.05) increased in PNT compared to treated groups. The Na⁺ and Cl^- were significantly (P < 0.05) reduced in PNT, with significantly (P < 0.05) increased K⁺ compared to NC and treated groups. Glomerulonephritis and glomerulus splitting was observed in PNT, while moderate distortions were observed in treated groups. The AA and AM groups had good kidney histoarchitecture.

Conclusion

Parasitemia decreased in all the treatment groups except in PNT and ASP groups which had severe hepatorenal distortions. Hepatorenal histoarchitecture were mildly distorted in the AA, AM and AL-administered groups with lower hepatorenal indices comparable to NC. The least elevated liver enzymes were in AA and AM. In decreasing order ASP > DP > AL > AP > AM > AA.

Systematic review of artesunate pharmacokinetics: Implication for treatment of resistant malaria

BACKGROUND

Artesunate (ART) is an artemisinin derivative used as monotherapy for the treatment of severe malaria and in combination with a partner drug for non-severe malaria. Resistance of malaria parasites to artemisinins have emerged in Southeast Asia. Adjustment of drug regimen may be an option to prevent therapeutic failures considering the relative favourable safety profile of ART high doses.

METHODS

For that purpose, a systematic review was done using PubMed, Scopus and Web of Science databases. All studies on ART and DHA pharmacokinetic post-administration of artesunate in human patients or volunteers were included. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist 2009 was used.

FINDINGS

Fifty studies exploring oral, intravenous, rectal, and intramuscular route (1470 persons, volunteers and patients) were included. Correlations between artesunate doses and C_max or AUC_0-∞ of dihydroartemisinin (DHA) and DHA+ART were evaluated. This correlation was good (R²>0.9) using intravenous (IV) route. DHA and ART+DHA average concentrations (Cav) were well above estimated in vivo half-maximal effective concentration (EC₅₀) for intravenous route, but this was not the case for oral route.

INTERPRETATION

The favorable Cav/EC₅₀ ratio for IV route provides evidence that IV ART will remain efficient even in the case of increased resistance level, whereas for the oral route, a two-fold increase in EC₅₀ may lead to therapeutic failures, thus providing a rationale for oral dose escalation. Considering the inter-individual variability of ART pharmacokinetic, Therapeutic Drug Monitoring through antimalarial stewardship activities is needed to optimize drug exposure and avoid resistance development.

Management of severe imported malaria in adults

Severe malaria accounts for approximately 10% of all cases of imported malaria in France; cases are mainly due to Plasmodium falciparum, while other Plasmodium species are possible but uncommon (P. vivax, P. knowlesi, P. malariae, and P. ovale). On the basis of WHO criteria for endemic areas, the French criteria defining severe imported malaria in adults have been progressively adapted to the European healthcare level. Management of severe imported malaria is a diagnostic and treatment emergency and must be initially conducted in the intensive care unit. Anti-infective treatment is now based on intravenous artesunate, which must be available in every hospital of the country likely to receive severe imported malaria patients. Intravenous quinine is thus used as a second-line treatment and is restricted to limited indications. Critical care management of organ failure is essential, particularly in patients presenting with very severe malaria. To date, no adjunctive therapy (including exchange transfusion) has demonstrated clear beneficial effects.

Prise en charge du paludisme grave d’importation de l’adulte

En France, le paludisme grave d’importation concerne environ 12 à 14 % des accès palustres et implique très majoritairement Plasmodium falciparum. À partir de la définition du paludisme grave de l’Organisation mondiale de la santé utilisée en zone d’endémie palustre, la définition française du paludisme grave d’importation de l’adulte a été adaptée aux données et au contexte européens. La prise en charge du paludisme grave est une urgence diagnostique et thérapeutique qui doit être réalisée initialement en réanimation. Le traitement curatif du paludisme grave d’importation repose maintenant sur l’artésunate intraveineux (IV) qui doit être disponible dans chaque hôpital susceptible de recevoir ces patients. Dès lors, la quinine IV devient un traitement de seconde ligne réservé à quelques circonstances. La prise en charge symptomatique des défaillances d’organes est primordiale, notamment au cours des formes les plus sévères. Enfin, aucun traitement adjuvant n’a prouvé, à ce jour, son efficacité en pratique clinique.

Artesunate shows potent anti-tumor activity in B-cell lymphoma

BACKGROUND

Although chemo-immunotherapy has led to an improved overall survival for most B-cell lymphoma types, relapsed and refractory disease remains a challenge. The malaria drug artesunate has previously been identified as a growth suppressor in some cancer types and was tested as a new treatment option in B-cell lymphoma.

METHODS

We included artesunate in a cancer sensitivity drug screen in B lymphoma cell lines. The preclinical properties of artesunate was tested as single agent in vitro in 18 B-cell lymphoma cell lines representing different histologies and in vivo in an aggressive B-cell lymphoma xenograft model, using NSG mice. Artesunate-treated B lymphoma cell lines were analyzed by functional assays, gene expression profiling, and protein expression to identify the mechanism of action.

RESULTS

Drug screening identified artesunate as a highly potent anti-lymphoma drug. Artesunate induced potent growth suppression in most B lymphoma cells with an IC50 comparable to concentrations measured in serum from artesunate-treated malaria patients, while leaving normal B-cells unaffected. Artesunate markedly inhibited highly aggressive tumor growth in a xenograft model. Gene expression analysis identified endoplasmic reticulum (ER) stress and the unfolded protein response as the most affected pathways and artesunate-induced expression of the ER stress markers ATF-4 and DDIT3 was specifically upregulated in malignant B-cells, but not in normal B-cells. In addition, artesunate significantly suppressed the overall cell metabolism, affecting both respiration and glycolysis.

CONCLUSIONS

Artesunate demonstrated potent apoptosis-inducing effects across a broad range of B-cell lymphoma cell lines in vitro, and a prominent anti-lymphoma activity in vivo, suggesting it to be a relevant drug for treatment of B-cell lymphoma.

Artesunate to treat severe malaria in travellers: review of efficacy and safety and practical implications

BACKGROUND

Artesunate (AS) is the WHO first-line treatment of severe malaria in endemic countries, in adults and children. However, despite solid evidence that AS is safe and more effective than quinine in endemic areas, its deployment in non-endemic areas has been slow, due in part to the absence of a full good manufacturing practice (GMP) qualification (although prequalification has been granted in 2010). Prospective comparative trials were not conducted in travellers, but several retrospective studies and case reports are providing insights into the efficacy and safety of AS in imported severe malaria.

METHODS

We performed a systematic review on AS use in non-endemic areas for the treatment of imported severe malaria, using the Prisma method for bibliographic reports. Post-AS delayed haemolysis (PADH) was defined by delayed haemolytic episodes occurring 7-30 days after treatment initiation. We summarized prescription guidelines and generated answers to frequently asked questions regarding the use of AS in travellers with severe malaria.

RESULTS

We analysed 12 retrospectives and 1 prospective study as well as 7 case reports of AS treatment in 624 travellers. Of 574 patients with reported outcome, 23 died (4%). No death was attributed to AS toxicity. Non-haematological side effects were uncommon and mainly included mild hepatitis, neurological, renal, cutaneous and cardiac manifestations. PADH occurred in 15% of the treated patients. No death or sequelae were reported. Overall blood transfusion was administered in 50% of travellers with PADH.

CONCLUSION

AS is highly efficacious in travellers with severe malaria. The frequency of PADH supports the need of weekly follow-up of haematological parameters during 1 month. Full GMP qualification for the drug and rapid approval by drug agencies is warranted, backed by clear recommendations for optimal use.

Comparative pharmacokinetics and pharmacodynamics of intravenous artelinate versus artesunate in uncomplicated Plasmodium coatneyi-infected rhesus monkey model

Background

The US Army designed artelinate/lysine salt (AL) to overcome the instability of sodium artesunate in aqueous solution (AS). To select the most efficacious artemisinin treatment, direct comparison was performed in an uncomplicated non-human primate malaria model.

Methods

Splenectomized rhesus monkeys were inoculated with Plasmodium coatneyi and on day six, single equimolar loading dose of IV AL (11.8 mg kg⁻¹) or IV AS (8 mg kg⁻¹) were administered followed by 1/2 the first dose once daily for 2 more days. Blood smear were performed twice daily and the number of parasites were counted microscopically. Blood samples were obtained after the first dose within 6 h for pharmacokinetic (PK) and ex vivo pharmacodynamic evaluation by simultaneously measuring plasma drug concentration and anti-malarial activity against Plasmodium falciparum in vitro.

Results

The anti-P. coatneyi in vivo activity of both compounds were comparable, but the ex vivo anti-P. falciparum potency of the IV AS regimen as administered was sevenfold higher than that of IV AL. Comparing in vivo pharmacodynamics of AL and AS, daily assessed parasite counts showed comparable 99 % parasite clearance times (PC99: 2.03, 1.84 day), parasite clearance rates (5.34, 4.13 per min) and clearance half-life (PCt_1/2: 7.79, 10.1 h). This study showed strong and significant inverse correlation between PCt_1/2 and t_1/2 of AS + DHA, and AUC_0–∞ of DHA, and correlated with V_z of AS (r² > 0.7, p ≤ 0.002). Lastly, following IV AL, there was a modest inverse correlation between PCt_1/2 and C_max (r² 0.6, p ≤ 0.04). Although all tested monkeys recrudesced subsequently, two died following AL regimen before parasite clearance. While the aetiology of those deaths could not be definitively determined, pathologic evidence favoured a sepsis-like syndrome and suggested that severe malaria was more likely than drug toxicity.

Conclusion

The model demonstrated that both AS and DHA contributed to the anti-malarial activity of IV AS, while IV AL activity was largely restricted to the parent drug. Parasite clearance was strongly and linearly dependent on drug exposure for both artemisinin regimens. However, IV AS had higher ex vivo potency against P. falciparum, leading to an IND filing for GMP manufactured AS in the United States.

Electronic supplementary material

The online version of this article (doi:10.1186/s12936-016-1456-6) contains supplementary material, which is available to authorized users.

Artesunate, an anti-malarial drug, has a potential to inhibit HCV replication

Hepatitis C virus (HCV) infection is a major global health issue. Although the search for HCV treatments has resulted in great achievements, the current treatment methods have limitations, and new methods and drugs for hepatitis C treatment are still required. The aim of the present study was to investigate the effects of artesunate (ART) on HCV replication and compared these effects with those of ribavirin (RBV) and interferon-2b (IFN). The study was performed in HCV-infection cell models (JFH1-infected Huh7.5.1 and OR6 cell lines). Our results showed that the antimalarial drug ART inhibited HCV replicon replication in a dose- and time-dependent manner at a concentration that had no effect on the proliferation of exponentially growing host cells, and the inhibitory effect on HCV replication was stronger than RBV but weaker than IFN, as determined by qPCR, luciferase assays, and Western blot analysis. Furthermore, the combination of ART and IFN resulted in a greater inhibition of HCV replication. These findings demonstrated that ART had an inhibitive effect on HCV replication and may be a novel supplemental co-therapy with IFN and RBV for HCV and as an alternative strategy to combat resistance mechanisms that have emerged in the presence of DAA agents.

Intravenous Artesunate for the Treatment of Severe and Complicated Malaria in the United States: Clinical Use Under an Investigational New Drug Protocol

BACKGROUND

Quinidine gluconate, the only U.S. Food and Drug Administration-approved treatment for life-threatening malaria in the United States, has a problematic safety profile and is often unavailable in hospitals.

OBJECTIVE

To assess the safety and clinical benefit of intravenous artesunate as an alternative to quinidine.

DESIGN

Retrospective case series.

SETTING

U.S. hospitals.

PATIENTS

102 patients aged 1 to 72 years (90% adults; 61% men) with severe and complicated malaria. Patients received 4 weight-based doses of intravenous artesunate (2.4 mg/kg) under a treatment protocol implemented by the Centers for Disease Control and Prevention between January 2007 and December 2010. At baseline, 35% had evidence of cerebral malaria, and 17% had severe hepatic impairment. Eligibility required the presence of microscopically confirmed malaria, need for intravenous treatment, and an impediment to quinidine.

MEASUREMENTS

Clinical and laboratory data from each patient's hospital records were abstracted retrospectively, including information from baseline through a maximum 7-day follow-up, and presented before a physician committee to evaluate safety and clinical benefit outcomes.

RESULTS

7 patients died (mortality rate, 6.9%). The most frequent adverse events were anemia (65%) and elevated hepatic enzyme levels (49%). All deaths and most adverse events were attributed to the severity of malaria. Patients' symptoms generally improved or resolved within 3 days, and the median time to discharge from the intensive care unit was 4 days, even for patients with severe liver disease or cerebral malaria. More than 100 concomitant medications were used, with no documented drug-drug interactions.

LIMITATION

Potential late-presenting safety issues might occur outside the 7-day follow-up.

CONCLUSION

Artesunate was a safe and clinically beneficial alternative to quinidine.

CUSP9* treatment protocol for recurrent glioblastoma: aprepitant, artesunate, auranofin, captopril, celecoxib, disulfiram, itraconazole, ritonavir, sertraline augmenting continuous low dose temozolomide

CUSP9 treatment protocol for recurrent glioblastoma was published one year ago. We now present a slight modification, designated CUSP9*. CUSP9* drugs--aprepitant, artesunate, auranofin, captopril, celecoxib, disulfiram, itraconazole, sertraline, ritonavir, are all widely approved by regulatory authorities, marketed for non-cancer indications. Each drug inhibits one or more important growth-enhancing pathways used by glioblastoma. By blocking survival paths, the aim is to render temozolomide, the current standard cytotoxic drug used in primary glioblastoma treatment, more effective. Although esthetically unpleasing to use so many drugs at once, the closely similar drugs of the original CUSP9 used together have been well-tolerated when given on a compassionate-use basis in the cases that have come to our attention so far. We expect similarly good tolerability for CUSP9*. The combined action of this suite of drugs blocks signaling at, or the activity of, AKT phosphorylation, aldehyde dehydrogenase, angiotensin converting enzyme, carbonic anhydrase -2,- 9, -12, cyclooxygenase-1 and -2, cathepsin B, Hedgehog, interleukin-6, 5-lipoxygenase, matrix metalloproteinase -2 and -9, mammalian target of rapamycin, neurokinin-1, p-gp efflux pump, thioredoxin reductase, tissue factor, 20 kDa translationally controlled tumor protein, and vascular endothelial growth factor. We believe that given the current prognosis after a glioblastoma has recurred, a trial of CUSP9* is warranted.

Artesunate overcomes drug resistance in multiple myeloma by inducing mitochondrial stress and non-caspase apoptosis

Although novel drugs have contributed immensely to improving outcomes of patients with multiple myeloma (MM), many patients develop drug resistance and ultimately succumb to MM. Here, we show that artesunate, an anti-malarial drug, reliably induces cell death in vitro in naïve as well as drug-resistant MM cells at concentrations shown to be safe in humans. Artesunate induced apoptosis predominantly through the non-caspase mediated pathway by primarily targeting mitochondria and causing outer mitochondrial membrane permeabilization that led to cytosolic and subsequent nuclear translocation of mitochondrial proteins apoptosis inducing factor (AIF) and endonuclease G (EndoG). Nuclear translocation of AIF and EndoG was accompanied by low levels of reactive oxygen species (ROS) and increased mitochondrial production of superoxide. These effects were present before apoptosis was evident and were related to intracellular levels of bivalent iron (Fe+2). Artesunate's unique mechanism probably was at least partially responsible for, its ability to act synergistically with multiple anti-myeloma agents. Our findings suggest that artesunate acts through iron to affect the mitochondria and induce low ROS and non-caspase-mediated apoptosis. Its potency, toxicity profile, and synergism with other drugs make it an intriguing new candidate for MM treatment.

Efficacy of intravenous methylene blue, intravenous artesunate, and their combination in preclinical models of malaria

Background

Intravenous artesunate (IV AS) is the present treatment of choice for severe malaria, but development of artemisinin resistance indicates that a further agent will be needed. Methylene blue (MB) is an approved human agent for IV and oral use, and is already being investigated for oral treatment of uncomplicated malaria. To initiate investigation of IV MB for severe malaria, the efficacy of IV MB was compared to IV AS and to their combination in rat and non-human primate malaria models.

Methods

IV MB was compared to IV AS and to their combination in the Plasmodium berghei-infected rat, a self-curing model; the Plasmodium falciparum-infected Aotus monkey, a fatal model; and the Plasmodium cynomolgi-infected rhesus monkey, a fatal model. Key endpoints were clearance of all parasites from the blood and cure (clearance without recrudescence).

Results

In rats, the minimal dose of individual drugs and their combination that cleared parasites from all animals was 20 mg IV MB/kg/day, 60 mg IV AS/kg/day and 10 mg IV MB/kg/day plus 30 mg IV AS/kg/day. In Aotus, 8 mg IV MB/kg/day and 8 mg IV AS/kg/day each cured two of three monkeys by one day after therapy, and the third monkey in each group was cured two days later. The combination of both drugs did not result in superior efficacy. In rhesus, 8 mg IV MB/kg/day and 8 mg IV AS/kg/day performed comparably: parasite clearance occurred by day 3 of therapy, although only one of four animals in each dose group cured. Eight mg/kg/day of both drugs in combination was 100% successful: all four of four animals cured.

Conclusions

In each of the three animal models, the efficacy of IV MB was approximately equal to that of standard of care IV AS. In the rat and rhesus models, the combination was more effective than either single agent. This preclinical data suggests that IV MB, alone or in combination with IV AS, is effective against Plasmodium spp. and can be evaluated in severe malaria models.

Antiviral effects of artesunate on JC polyomavirus replication in COS-7 cells

The human JC polyomavirus (JCPyV) causes the fatal demyelinating disease progressive multifocal leukoencephalopathy (PML). A growing number of patients with induced or acquired immunosuppression are at risk for infection, and no effective antiviral therapy is presently available. The widely used antimalarial drug artesunate has shown broad antiviral activity in vitro but limited clinical success. The aim of this study was to investigate the effect of artesunate on JCPyV replication in vitro. The permissivity for JCPyV MAD-4 was first compared in four cell lines, and the monkey kidney cell line COS-7 was selected. Artesunate caused a concentration-dependent decrease in the extracellular JCPyV DNA load 96 h postinfection, with a 50% effective concentration (EC50) of 2.9 μM. This effect correlated with a decreased expression of capsid protein VP1 and a reduced release of infectious viral progeny. For concentrations of <20 μM, transient reductions in cellular DNA replication and proliferation were seen, while for higher concentrations, some cytotoxicity was detected. A selective index of 16.6 was found when cytotoxicity was calculated based on cellular DNA replication in the mock-infected cells, but interestingly, cellular DNA replication in the JCPyV-infected cells was more strongly affected. In conclusion, artesunate is efficacious in inhibiting JCPyV replication at micromolar concentrations, which are achievable in plasma. The inhibition at EC50 probably reflects an effect on cellular proteins and involves transient cytostatic effects. Our results, together with the favorable distribution of the active metabolite dihydroartemisinin to the central nervous system, suggest a potential use for artesunate in patients with PML.

Interspecies allometric scaling of antimalarial drugs and potential application to pediatric dosing

Pharmacopeial recommendations for administration of antimalarial drugs are the same weight-based (mg/kg of body weight) doses for children and adults. However, linear calculations are known to underestimate pediatric doses; therefore, interspecies allometric scaling data may have a role in predicting doses in children. We investigated the allometric scaling relationships of antimalarial drugs using data from pharmacokinetic studies in mammalian species. Simple allometry (Y = a × W(b)) was utilized and compared to maximum life span potential (MLP) correction. All drugs showed a strong correlation with clearance (CL) in healthy controls. Insufficient data from malaria-infected species other than humans were available for allometric scaling. The allometric exponents (b) for CL of artesunate, dihydroartemisinin (from intravenous artesunate), artemether, artemisinin, clindamycin, piperaquine, mefloquine, and quinine were 0.71, 0.85, 0.66, 0.83, 0.62, 0.96, 0.52, and 0.40, respectively. Clearance was significantly lower in malaria infection than in healthy (adult) humans for quinine (0.07 versus 0.17 liter/h/kg; P = 0.0002) and dihydroartemisinin (0.81 versus 1.11 liters/h/kg; P = 0.04; power = 0.6). Interpolation of simple allometry provided better estimates of CL for children than MLP correction, which generally underestimated CL values. Pediatric dose calculations based on simple allometric exponents were 10 to 70% higher than pharmacopeial (mg/kg) recommendations. Interpolation of interspecies allometric scaling could provide better estimates than linear scaling of adult to pediatric doses of antimalarial drugs; however, the use of a fixed exponent for CL was not supported in the present study. The variability in allometric exponents for antimalarial drugs also has implications for scaling of fixed-dose combinations.

Pharmacokinetic evaluation of intravenous artesunate in adults with uncomplicated falciparum malaria in Kenya: a phase II study

Background

Alternatives to treatment for malaria treatment of travellers are needed in the USA and in Europe for travellers who return with severe malaria infections. The objective of this study is to show the pharmacokinetic (PK) profile of intravenous artesunate (AS), which was manufactured under good manufacturing practice (GMP) conditions, in adults with uncomplicated falciparum malaria in Kenya.

Methods

The PK parameters of intravenous AS manufactured under current cGMP were evaluated after a single dose of drug at 2.4 mg/kg infused over 2 min in 28 adults with uncomplicated Plasmodium falciparum malaria. Plasma concentrations of AS and dihydroartemisinin (DHA) were measured using a validated liquid chromatography–mass spectrometry (LC-MS/MS) methodology. Pharmacokinetic data were analysed with a compartmental analysis for AS and DHA.

Results

The results suggest there were no drug-related adverse events in any of the patients. After intravenous infusion, the concentration of the parent drug rapidly declined, and the AS was converted to DHA. AS and DHA showed mean elimination half-lives of 0.17 hours and 1.30 hours, respectively. The high mean peak concentration (C_max) of AS was shown to be 28,558 ng/mL while the C_max of DHA was determined to be 2,932 ng/mL. Significant variability was noted in the PK profiles of the 28 patients tested. For example, C_max values of AS were calculated to range from 3,362 to 55,873 ng/mL, and the C_max value of DHA was noted to vary from 1,493 to 5,569 ng/mL. The mean area under the curve (AUC) of AS was shown to be approximately half that of DHA (1,878 ng·h/mL vs 3,543 ng·h/mL). The DHA/AS ratio observed was 1.94 during the one-day single treatment, and the AUC and half- life measured for DHA were significantly larger and longer than for AS.

Conclusions

Intravenous AS can provide much higher peak concentrations of AS when compared to concentrations achieved with oral therapy; this may be crucial for the rapid elimination of parasites in patients with severe malaria. Given the much longer half-life of DHA compared to the short half-life of AS, DHA also plays a significant role in treatment of severe malaria.

Dihydroartemisinin is a Hypoxia-Active Anti-Cancer Drug in Colorectal Carcinoma Cells

Tumor hypoxia is one main biological factor that drives resistance to chemotherapy and radiotherapy. To develop a novel strategy for overcoming hypoxia-induced therapy resistance, we examined the anti-neoplastic activity of the reactive oxygen donor dihydroartemisinin (DHA) in human colon cancer cell lines in normoxia and severe hypoxia. In addition, we analyzed the involvement of the intrinsic apoptosis pathway for DHA-mediated cytotoxicity in HCT116 cells in short-term and long-term in vitro assays. When applied at lower concentrations (≤25 μM), DHA induced apoptosis in Colo205, HCT15, and HCT116 cells, whereas necrotic cell death was increased when cells were treated with higher DHA concentrations (50 μM). However, no preference for DHA-induced apoptosis or necrosis could be detected between the treatment under normoxic or hypoxic conditions. Moreover, DHA potently reduced clonogenic survival of HCT116 cells in normoxia and hypoxia. Treatment of HCT116 cells with 25 μM DHA resulted in activation of Bax under normoxic and hypoxic conditions. Interestingly, cytochrome c release from the mitochondria and caspase-activation were observed only under normoxic conditions, whereas, under hypoxic conditions DHA induced a caspase-independent apoptosis-like cell death. However, under both conditions, generation of reactive oxygen species was an important mediator of DHA-induced toxicity. Further molecular analysis suggests that DHA-mediated cell death involves different sets of pro-apoptotic Bcl-2 family members. The pronounced cytotoxic activity of DHA in severe hypoxia as well as normoxia offers new perspectives for targeting the hypoxic tumor cell fraction to improve treatment outcome for cancer patients.

Antiviral effects of artesunate on polyomavirus BK replication in primary human kidney cells

Polyomavirus BK (BKV) causes polyomavirus-associated nephropathy (PyVAN) and hemorrhagic cystitis (PyVHC) in renal and bone marrow transplant patients, respectively. Antiviral drugs with targeted activity against BKV are lacking. Since the antimalarial drug artesunate was recently demonstrated to have antiviral activity, the possible effects of artesunate on BKV replication in human primary renal proximal tubular epithelial cells (RPTECs), the host cells in PyVAN, were explored. At 2 h postinfection (hpi), RPTECs were treated with artesunate at concentrations ranging from 0.3 to 80 μM. After one viral replication cycle (approximately 72 hpi), the loads of extracellular BKV DNA, reflecting viral progeny production, were reduced in a concentration-dependent manner. Artesunate at 10 μM reduced the extracellular BKV load by 65%; early large T antigen mRNA and protein expression by 30% and 75%, respectively; DNA replication by 73%; and late VP1 mRNA and protein expression by 47% and 64%, respectively. Importantly, the proliferation of RPTECs was also inhibited in a concentration-dependent manner. At 72 hpi, artesunate at 10 μM reduced cellular DNA replication by 68% and total metabolic activity by 47%. Cell impedance and lactate dehydrogenase measurements indicated a cytostatic but not a cytotoxic mechanism. Flow cytometry and 5-ethynyl-2'-deoxyuridine incorporation revealed a decreased number of cells in S phase and suggested cell cycle arrest in G0 or G2 phase. Both the antiproliferative and antiviral effects of artesunate at 10 μM were reversible. Thus, artesunate inhibits BKV replication in RPTECs in a concentration-dependent manner by inhibiting BKV gene expression and genome replication. The antiviral mechanism appears to be closely connected to cytostatic effects on the host cell, underscoring the dependence of BKV on host cell proliferative functions.

Establishment and assessment of a new human embryonic stem cell-based biomarker assay for developmental toxicity screening

A metabolic biomarker-based in vitro assay utilizing human embryonic stem (hES) cells was developed to identify the concentration of test compounds that perturbs cellular metabolism in a manner indicative of teratogenicity. This assay is designed to aid the early discovery-phase detection of potential human developmental toxicants. In this study, metabolomic data from hES cell culture media were used to assess potential biomarkers for development of a rapid in vitro teratogenicity assay. hES cells were treated with pharmaceuticals of known human teratogenicity at a concentration equivalent to their published human peak therapeutic plasma concentration. Two metabolite biomarkers (ornithine and cystine) were identified as indicators of developmental toxicity. A targeted exposure-based biomarker assay using these metabolites, along with a cytotoxicity endpoint, was then developed using a 9-point dose-response curve. The predictivity of the new assay was evaluated using a separate set of test compounds. To illustrate how the assay could be applied to compounds of unknown potential for developmental toxicity, an additional 10 compounds were evaluated that do not have data on human exposure during pregnancy, but have shown positive results in animal developmental toxicity studies. The new assay identified the potential developmental toxicants in the test set with 77% accuracy (57% sensitivity, 100% specificity). The assay had a high concordance (≥75%) with existing in vivo models, demonstrating that the new assay can predict the developmental toxicity potential of new compounds as part of discovery phase testing and provide a signal as to the likely outcome of required in vivo tests.

Stability and antiviral activity against human cytomegalovirus of artemisinin derivatives

OBJECTIVES

Artesunate, a derivative of dihydroartemisinin, itself a product of artemisinin, inhibits the replication of cytomegalovirus in vitro. In vivo, artesunate undergoes rapid conversion into the active metabolite dihydroartemisinin. The in vitro stability of the compounds and the antiviral activity of dihydroartemisinin are of great concern for the interpretation of in vitro testing. The aim of the study was to measure artesunate conversion into dihydroartemisinin in culture medium and to evaluate the stability and antiviral activity of artemisinin derivatives, according to culture conditions.

METHODS

Conversion of artesunate into dihydroartemisinin was measured in culture medium with or without fetal calf serum, in the presence or absence of fibroblast monolayers, at different times. The stability of artemisinin derivatives was determined in serum-enriched medium. Concentrations of each compound inhibiting viral DNA synthesis by 50% were determined in fibroblasts cultured in serum-free or serum-enriched medium, after addition of compound as a single dose or fractional doses.

RESULTS

Conversion of artesunate into dihydroartemisinin in serum-free or serum-enriched medium was non-equimolar. The half-lives of artesunate, dihydroartemisinin and artemisinin were 10.3 ± 0.9, 5.2 ± 0.5 and 11.2 ± 1.2 h, respectively. Activity of dihydroartemisinin and artesunate was markedly reduced in serum-starved cells. Unexpectedly, dihydroartemisinin displayed a lower activity than artesunate. Addition of both compounds as fractional doses increased their activity. Artemisinin had no anticytomegaloviral activity.

CONCLUSIONS

Artemisinin derivatives were shown to be unstable in vitro and their addition as fractional doses could partly compensate for this instability. Importantly, the cellular physiological condition was a determinant of their antiviral activity.

Lymphoma and myeloma cells are highly sensitive to growth arrest and apoptosis induced by artesunate

OBJECTIVES

The use of new drugs has improved the treatment of multiple myeloma and diffuse large B-cell lymphoma (DLBCL). Nevertheless, over time many patients relapse and develop resistance to treatment, and efforts are needed to overcome drug resistance. The widely used malaria drug artesunate has been reported to have antitumor activity, and we aimed to test the effects of artesunate on a panel of myeloma and lymphoma cells.

METHODS

Myeloma and DLBCL cell lines were treated with artesunate in vitro. The effects of artesunate treatment were evaluated using ATP content measurements for proliferation and annexin V/propidium iodide labeling for apoptosis. Western blotting was used to look for artesunate-induced protein changes. In addition, we measured artesunate effects on patient myeloma cells in the presence of bone marrow stromal cells.

RESULTS

Artesunate treatment efficiently inhibited cell growth and induced apoptosis in cell lines. Apoptosis was induced concomitantly with downregulation of MYC and anti-apoptotic Bcl-2 family proteins, as well as with cleavage of caspase-3. The IC50 values of artesunate in cell lines varied between 0.3 and 16.6 μm. Furthermore, some primary myeloma cells were also sensitive to artesunate at doses around 10 μm. Concentrations of this order are pharmacologically relevant as they can be obtained in plasma after intravenous administration of artesunate for malaria treatment.

CONCLUSION

Our findings indicate that artesunate is a potential drug for treatment of multiple myeloma and DLBCL at doses of the same order as currently in use for treatment of malaria without serious adverse effects.

Advances in the treatment of malaria

Malaria still claims a heavy toll of deaths and disabilities even at the beginning of the third millennium. The inappropriate sequential use of drug monotherapy in the past has facilitated the spread of drug-resistant P. falciparum, and to a lesser extend P. vivax, strains in most of the malaria endemic areas, rendering most anti-malarial ineffective. In the last decade, a new combination strategy based on artemisinin derivatives (ACT) has become the standard of treatment for most P. falciparum malaria infections. This strategy could prevent the selection of resistant strains by rapidly decreasing the parasitic burden (by the artemisinin derivative, mostly artesunate) and exposing the residual parasite to effective concentrations of the partner drug. The widespread use of this strategy is somehow constrained by cost and by the inappropriate use of artemisinin, with possible impact on resistance, as already sporadically observed in South East Asia. Parenteral artesunate has now become the standard of care for severe malaria, even if quinine still retains its value in case artesunate is not immediately available. The appropriateness of pre-referral use of suppository artesunate is under close monitoring, while waiting for an effective anti-malarial vaccine to be made available.