Auranofin: a unique oral chrysotherapeutic agent

Aurothioglucose encapsulated nanoparticles fostered neuroprotection in streptozotocin-induced Alzheimer's disease

Alzherimer's disease (AD) is an age-dependent ubiquitous ailment worldwide with limited therapies that only alleviate the symptoms of AD but do not cure them entirely because of the restricted blood-brain barrier passage of the drug. Hence with new advanced technology, nanoparticles can offer an opportunity as the active candidate to overcome the above limitations. Aurothioglucose, a synthetic glucose derivative of the gold compound, has been clinically proven to be an effective anti-inflammatory drug for rheumatic arthritis. Recently, several scientific groups have developed gold nanoparticle preparations and tested them for the treatment of dementia. This study was planned to prepare the PLGA nanoparticles of aurothioglucose (ATG) and check the neuroprotective potential against STZ-induced AD in rats. The nanoparticles were prepared using the double emulsion solvent evaporation method and characterized for various parameters such as drug-excipient interaction, particle size, zeta potential, and morphology. Then, rats were injected STZ (3 mg/kg/i.c.v., days 1 and 3) and ATG (5 and 10 mg/kg/s.c.), ATG NPs (2.5 and 5 mg/kg/s.c.) and donepezil (2 mg/kg/p.o) from 15th to 29th day. Behavior parameters were performed using an actophotometer, MWM, and ORT. On the 30th day, all the animals were sacrificed, and the brains were isolated for estimating biochemical, neurochemical, and proinflammatory markers. It was observed that ATG NPs significantly restored all behavior and neurotransmitter alterations caused by STZ. Also, it increased antioxidant levels and decreased inflammatory cytokines significantly, then ATG alone. Thus, the study suggests that ATG loaded PLGA NPs could be used as a novel therapeutic strategy to slow the process of AD.

Temperature rise and copper exposure reduce heart mitochondrial reactive oxygen species scavenging capacity

Mitochondria produce and scavenge reactive oxygen species (ROS); however, whether oxidative distress due to exogenous stress arises from excessive production or impaired scavenging remains unclear. We assessed the effect of copper (Cu) and thermal stress on kinetics of ROS (H₂O₂) consumption in mitochondria isolated from fish heart. Mitochondria were energized with succinate, glutamate-malate or palmitoylcarnitine (PC) and incubated with 1-25 μM Cu at 11 (control) and 23 °C. We found that H₂O₂ consumption capacity of heart mitochondria varies with substrate and is additively reduced by temperature rise and Cu. While Cu is a potent inhibitor of H₂O₂ consumption in mitochondria oxidizing glutamate-malate and succinate, mitochondria oxidizing PC are resistant to the inhibitory effect of the metal. Moreover, the sensitivity of H₂O₂ consumption pathways to Cu depend on the substrate and are greatly impaired during oxidation of glutamate-malate. Pharmacological manipulation of mitochondrial antioxidant systems revealed that NADPH-dependent peroxidase systems are the centerpieces of ROS scavenging in heart mitochondria, with the glutathione-dependent pathway being the most prominent while catalase played a minimal role. Surprisingly, Cu is as efficacious in inhibiting thioredoxin-dependent peroxidase pathway as auranofin, a selective inhibitor of thioredoxin reductase. Taken together, our study uncovered unique mechanisms by which Cu alters mitochondrial H₂O₂ homeostasis including its ability to inhibit specific mitochondrial ROS scavenging pathways on a par with conventional inhibitors. Importantly, because of additive inhibitory effect on mitochondrial ROS removal mechanisms, hearts of organisms jointly exposed to Cu and thermal stress are likely at increased risk of oxidative distress.

Anti-fibrotic activity of gold and platinum complexes - Au(I) compounds as a new class of anti-fibrotic agents

Molecular gold(I) and platinum(II) species were examined for the inhibition of liver fibrosis and the hepatitis C virus (HCV). Determination of inhibition efficiency was conducted via morphological analysis, cell viability, western blot analysis, and quantitative reverse transcription polymerase chain reaction (RT-PCR). Auranofin and Ph₃PAuCl demonstrated the greatest inhibition of liver fibrosis amongst the tested gold species in human hepatic stellate LX-2 cells. Western blot analysis indicated that auranofin and Ph₃PAuCl prevent signal transducer and activator of transcription 3 (STAT3) phosphorylation, which may be a key connection to fibrosis and inflammation. Auranofin and Ph₃PAuCl also reduced expression of HCV-nonstructural protein 3 (NS3) and HCV-NS5a proteins in a HCV subgenomic replicon system. These results demonstrate significant promise for the use of gold compounds in treating liver diseases such as HCV.

Challenges and Chances in the Preclinical to Clinical Translation of Anticancer Metallodrugs

Despite being “sentenced to death” for quite some time, anticancer platinum compounds are still the most frequently prescribed cancer therapies in the oncological routine and recent exciting news from late-stage clinical studies on combinations of metallodrugs with immunotherapies suggest that this situation will not change soon. It is perhaps surprising that relatively simple molecules like cisplatin, discovered over 50 years ago, are still widely used clinically, while none of the highly sophisticated metal compounds developed over the last decade, including complexes with targeting ligands and multifunctional (nano)formulations, have managed to obtain clinical approval. In this book chapter, we summarize the current status of ongoing clinical trials for anticancer metal compounds and discuss the reasons for previous failures, as well as new opportunities for the clinical translation of metal complexes.

New drug target in protozoan parasites: the role of thioredoxin reductase

Amebiasis causes approximately 70,000 deaths annually and is the third cause of death due to parasites worldwide. It is treated primarily with metronidazole, which has adverse side effects, is mutagenic and carcinogenic, and emergence of resistance is an increasing concern. Unfortunately, better therapeutic alternatives are lacking. Re-purposing of older FDA approved drugs is advantageous to drug discovery since safety and pharmacokinetic effects in humans are already known. In high throughput screening studies, we recently demonstrated that auranofin, a gold containing compound originally approved to treat rheumatoid arthritis, has activity against trophozoites of E. histolytica, the causative agent of amebiasis. Auranofin's anti-parasitic activity is attributed to its monovalent gold molecule that readily inhibits E. histolytica thioredoxin reductase. This anti-oxidant enzyme is the only thiol-dependent flavo-reductase present in E. histolytica. Auranofin has also shown promising activity against other protozoans of significant public health importance. Altogether, this evidence suggests that auranofin has the potential to become a broad spectrum alternative therapeutic agent for diseases with a large global burden.

Repurposing auranofin as a lead candidate for treatment of lymphatic filariasis and onchocerciasis

Two major human diseases caused by filariid nematodes are onchocerciasis, or river blindness, and lymphatic filariasis, which can lead to elephantiasis. The drugs ivermectin, diethylcarbamazine (DEC), and albendazole are used in control programs for these diseases, but are mainly effective against the microfilarial stage and have minimal or no effect on adult worms. Adult Onchocerca volvulus and Brugia malayi worms (macrofilariae) can live for up to 15 years, reproducing and allowing the infection to persist in a population. Therefore, to support control or elimination of these two diseases, effective macrofilaricidal drugs are necessary, in addition to current drugs. In an effort to identify macrofilaricidal drugs, we screened an FDA-approved library with adult worms of Brugia spp. and Onchocerca ochengi, third-stage larvae (L3s) of Onchocerca volvulus, and the microfilariae of both O. ochengi and Loa loa. We found that auranofin, a gold-containing drug used for rheumatoid arthritis, was effective in vitro in killing both Brugia spp. and O. ochengi adult worms and in inhibiting the molting of L3s of O. volvulus with IC₅₀ values in the low micromolar to nanomolar range. Auranofin had an approximately 43-fold higher IC₅₀ against the microfilariae of L. loa compared with the IC₅₀ for adult female O. ochengi, which may be beneficial if used in areas where Onchocerca and Brugia are co-endemic with L. loa, to prevent severe adverse reactions to the drug-induced death of L. loa microfilariae. Further testing indicated that auranofin is also effective in reducing Brugia adult worm burden in infected gerbils and that auranofin may be targeting the thioredoxin reductase in this nematode.

Onchocerciasis or river blindness, and lymphatic filariasis, which can lead to disfiguring elephantiasis, are two neglected tropical diseases that affect millions of people, primarily in developing countries. Both diseases are caused by filariid nematodes; onchocerciasis is caused by Onchocerca volvulus and lymphatic filariasis is caused by Brugia malayi, B. timori, and Wuchereria bancrofti. Currently, there are no drugs available that are highly efficacious against adult worms; existing drugs mainly kill the first-stage larvae (microfilariae). While these drugs can reduce the transmission of infections in a population, the adult filariids (macrofilariae) can continue to produce microfilariae and perpetuate the cycle of infection. Finding a drug that could kill the adult worms would be an important tool in eliminating onchocerciasis and lymphatic filariasis. To identify potential macrofilaricidal drugs, we developed a high throughput screening method to test FDA-approved drugs on adult Brugia spp., which serves as a model for O. volvulus. Using this screening method, we identified a drug called auranofin that kills adult Onchocerca and adult Brugia spp. in vitro, inhibits the molting of O. volvulus L3s, and reduces the worm burden in an in vivo gerbil-B. pahangi model system. Auranofin is known to inhibit a critical enzyme called thioredoxin reductase in some parasite species, and subsequent testing of the effects of auranofin on the thioredoxin reductase of Brugia indicates that this may be auranofin’s mode of action in this nematode as well.

Auranofin promotes retinoic acid- or dihydroxyvitamin D3-mediated cell differentiation of promyelocytic leukaemia cells by increasing histone acetylation

BACKGROUND AND PURPOSE

To investigate the molecular mechanism for the effect of auranofin on the induction of cell differentiation, the cellular events associated with differentiation were analysed in acute promyelocytic leukaemia (APL) cells.

EXPERIMENTAL APPROACH

The APL blasts from leukaemia patients and NB4 cells were cotreated with auroanofin and all-trans-retinoic acid (ATRA) at suboptimal concentration. The HL-60 cells were treated with auroanofin and a subeffective dose of 1alpha,25-dihydroxyvitamin D3 (1,25(OH)2 vit D3) in combination. The effect of auroanofin was investigated on histone acetylation at the promoter of differentiation-associated genes and expression of cell cycle regulators.

KEY RESULTS

Treatment with auroanofin and ATRA cooperatively induced granulocytic differentiation of fresh APL blasts isolated from patients and NB4 cells. The combined treatment also increased reorganization of nuclear PML bodies and histone acetylation at the promoter of the RARbeta2 gene. Auroanofin also promoted monocytic differentiation of the HL-60 cells triggered by subeffective concentration of 1,25(OH)2 vit D3. The combined treatment of auroanofin and 1,25(OH)2 vit D3 stimulated histone acetylation at p21 promoters and increased the accumulation of cells in the G0/G1 phase. Consistent with this, the expressions of p21, p27 and PTEN were increased and the levels of cyclin A, Cdk2 and Cdk4 were decreased. Furthermore, the hypophosphorylated form of pRb was markedly increased in cotreated cells.

CONCLUSIONS AND IMPLICATIONS

These findings indicate that auroanofin in combination with low doses of either ATRA or 1,25(OH)2 vit D3 promotes APL cell differentiation by enhancing histone acetylation and the expression of differentiation-associated genes.

Gold salts, D-penicillamine and allopurinol

Gold salts have been used in the treatment of patients with rheumatoid arthritis since 1927 [1]. After a controlled study, the Empire Rheumatism Council [2], confirmed the effectiveness of gold salts for the treatment of rheumatoid arthritis. Even today, chrysotherapy has remained one of the major therapeutic modalities in the second line treatment of progressive rheumatoid arthritis. Gold salts are also used in the treatment of pemphigus vulgaris [3] and bronchial asthma [4]. Before the introduction of an orally administered gold compound, auranofin (triethylphosphine gold tetra-acetyl glycopyranoside), to clinical use [5-7], parenterally administered gold salts, such as sodium aurothiomalate and gold thioglucose comprised chrysotherapy. The frequency and severity of the side effects for patients treated with parenteral gold versus those given oral gold preparations are significantly different [8-10]. With introduction of newer parental DMARDs, toxicity has been reduced using combination therapy [10a, 10b].

Inorganics and hormesis

The article is a comprehensive review of the occurrence of hormetic dose-response relationships induced by inorganic agents, including toxic agents, of significant environmental and public health interest (e.g., arsenic, cadmium, lead, mercury, selenium, and zinc). Hormetic responses occurred in a wide range of biological models (i.e., plants, invertebrate and vertebrate animals) for a large and diverse array of endpoints. Particular attention was given to providing an assessment of the quantitative features of the dose-response relationships and underlying mechanisms that could account for the biphasic nature of the hormetic response. These findings indicate that hormetic responses commonly occur in appropriately designed experiments and are highly generalizeable with respect to biological model responses. The hormetic dose response should be seen as a reliable feature of the dose response for inorganic agents and will have an important impact on the estimated effects of such agents on environmental and human receptors.

Inhibition of interleukin-12 production by auranofin, an anti-rheumatic gold compound, deviates CD4(+) T cells from the Th1 to the Th2 pathway

1. Interleukin-12 (IL-12) may play a central role in the development and progression of rheumatoid arthritis by driving the immune response towards T helper 1 (Th1) type responses characterized by high IFN-gamma and low IL-4 production. In this study we investigated the effect of auranofin (AF), an anti-rheumatic gold compound, on IL-12 production in mouse macrophages and dendritic cells, and studied whether AF-mediated inhibition of IL-12 production could regulate a cytokine profile of antigen (Ag)-primed CD4(+) Th cells. 2. Treatment with AF significantly inhibited IL-12 production in lipopolysaccharide (LPS)-stimulated macrophages and also in CD40L-stimulated dendritic cells. AF-pretreated macrophages reduced their ability to induce IFN-gamma and increased the ability to induce IL-4 in Ag-primed CD4(+) T cells. AF did not influence the cell surface expression of the class II MHC molecule and the costimulatory molecules CD80 and CD86. 3. Addition of recombinant IL-12 to cultures of AF-pretreated macrophages and CD4(+) T cells restored IFN-gamma production in Ag-primed CD4(+) T cells. 4. The in vivo administration of AF resulted in the inhibition of IL-12 production by macrophages stimulated in vitro with LPS or heat-killed Listeria monocytogenes (HKL), leading to the inhibition of Th1 cytokine profile (decreased IFN-gamma and increased IL-4 production) in Ag-primed CD4(+) T cells. 5. These findings may explain some known effects of AF including anti-rheumatic effects and the inhibition of encephalitogenicity, and point to a possible therapeutic use of AF in the Th1-mediated immune diseases such as autoimmune diseases.

The moderate intestinal side effects of auranofin do not require prophylactic therapy with a bulkforming agent. Dutch Ridaura Study Group

Incidences of diarrhoea and loose stools are reported up to 50% in patients starting treatment with auranofin. Moreover, +/-4% of patients discontinue treatment because of severe diarrhoea. We investigated whether a water binding agent would diminish the incidence of loose stools and diarrhoea. Endpoints were the patient's general impression of the quality of stools and a daily assessment of stool's frequency/consistency and adverse events. Secondly, some disease activity parameters were used to evaluate whether the bulkforming agent influences the efficacy of auranofin. In this study 269 patients suffering from Rheumatoid Arthritis (RA) were treated with auranofin 6 mgr daily for a period of six months. Simultaneously the patients were randomly treated with either a bulkforming agent (Volcolon: psyllium fibres) or placebo. Results show a 15% incidence of loose stools and diarrhoea during treatment with auranofin. During the treatment period the patients' general impression of defecation consistency showed a shift to softer types. The changes in defecation consistency was not significantly different between groups (Intention-to-treat analysis: C2=4.01; p=0.13). Also, the percentage of patients experiencing episodes of diarrhoea (reported as an adverse experience) was not different (14% of the patients treated with bulkformer versus 15% with placebo). During the first month 7% (n=5) of placebo treated patients reported short episodes of watery stools versus none in the bulkformer treated group. The percentage of days with loose or watery stools, reported on the diary cards, was consistently lower in bulkformer treated patients. Both groups improved equally with respect to disease activity parameters. Sixty-eight percent of patients continued auranofin treatment after the study period. In conclusion, these data do not support adjuvant therapy with a bulkforming agent on initiation of auranofin therapy. The overall low incidence of loose stools and diarrhoea suggests that a dose increase to 9 mgr daily is an option to enhance the efficacy of auranofin treatment.

Randomized trial of switching rheumatoid arthritis patients in remission with injectable gold to auranofin

This prospective unblinded 24-month-study compared the therapeutic value of oral gold with injectable gold to maintain rheumatoid arthritis (RA) patients in clinical remission and prevent the progression of erosive disease. Forty-six patients with definite RA in remission with injectable gold were randomized into two groups: a control group, continued on maintenance injectable gold (Solganal, aurothioglucose, 50-100 mg, intramuscularly, 2 to 4 weeks); and an experimental group, switched to oral gold (6-9 mg auranofin by mouth daily). Only 29% of the original 24 oral gold patients remained on assigned treatment at 24 months compared with 64% of the injectable gold group. By six months, over one-half of the oral gold patients had electively stopped their randomized therapy. Sixty-seven percent of the oral gold patients had adverse reactions, mostly gastrointestinal complaints, compared with one proteinuria in the injectable gold group. The oral gold group experienced significantly more deterioration in all the primary measures of treatment effect over the follow-up period. At the termination of the trial, 88% of the group had increases of 5 or more points in radiographic scores suggesting progression of erosive disease compared with only 29% of the control group. These data suggest that oral gold is not an effective substitute for injectable gold in maintaining remission in rheumatoid arthritis.

Suppression of interleukin-2 and interleukin-2 receptor biosynthesis by gold compounds in in vitro activated human peripheral blood mononuclear cells

OBJECTIVE

To further investigate the mechanism of action of gold compounds by studying their effects on interleukin-2 (IL-2) and IL-2 receptor (IL-2R) biosynthesis.

METHODS

We cultured phytohemagglutinin- or anti-CD3 antibody-activated normal peripheral blood mononuclear cells (PBMC), as well as the erythroleukemic K562 cell line, in the presence of gold sodium thiomalate or auranofin. Tritiated thymidine incorporation assays, cytotoxicity assays, immunofluorescence analysis, enzyme-linked immunosorbent assay, Northern blot, and RNA dot-blot hybridization were used.

RESULTS

Gold compounds, at concentrations attainable in vivo, inhibited the proliferation of normal PBMC, with no evidence of direct cytotoxicity. This inhibitory effect was associated with a dose-dependent suppression of both IL-2 and IL-2R messenger RNA accumulation. In contrast, the same concentrations of gold compounds failed to inhibit the spontaneous proliferation of the IL-2-independent K562 cells.

CONCLUSION

Our findings suggest an IL-2/IL-2R-mediated mechanism for suppression of lymphocyte proliferation by gold compounds, which might account for the immunomodulatory effects of gold in patients with rheumatoid arthritis.

Comparison of auranofin, methotrexate, and the combination of both in the treatment of rheumatoid arthritis. A controlled clinical trial

OBJECTIVE

To compare the relative safety and efficacy of auranofin (AUR), methotrexate (MTX), and the combination of both in the treatment of active rheumatoid arthritis (RA).

METHODS

Three hundred thirty-five patients with active RA were entered into a 48-week, prospective, controlled, double-blind, multicenter trial and were randomly assigned to 1 of 3 treatment groups.

RESULTS

Two hundred eleven patients completed the trial. No remissions were seen, and there were no statistically significant differences among the treatment groups in the clinical or laboratory variables measured. Patients taking AUR alone had a slower onset of response than did patients taking MTX alone or in combination. Withdrawals because of adverse drug reactions were slightly more common for those taking combination therapy, but the differences were not statistically significant. Withdrawals because of lack of response were more common for single-drug therapy, with the difference between AUR and the combination reaching statistical significance. No unexpected adverse drug effects were identified, and all reactions resolved without sequelae.

CONCLUSION

Except for fewer withdrawals because of lack of response, combination therapy did not demonstrate any advantage in efficacy over single-drug treatment within the time frame of the study.

Auranofin in the treatment of juvenile rheumatoid arthritis. Results of the USA-USSR double-blind, placebo-controlled trial. The USA Pediatric Rheumatology Collaborative Study Group. The USSR Cooperative Children's Study Group

A 6-month double-blind, parallel, randomized, placebo-controlled multicenter trial of auranofin (0.15-0.20 mg/kg/day) was conducted in 231 children with juvenile rheumatoid arthritis (JRA) in the United States and in the Union of Soviet Socialist Republics. Approximately 80% of the children had polyarticular disease. The auranofin-treated patients showed greater mean decreases from baseline in 11 of the 12 articular disease indices measured than did the placebo-treated subjects after 3 months of therapy, and in 9 of the 12 indices after 6 months. However, the actual intergroup mean differences were relatively small and were not statistically significant. According to the physician's global assessment, 69% of the auranofin-treated patients and 61% of the placebo-treated patients demonstrated clinically significant improvement from baseline after 6 months (P = 0.24). Children whose disease onset occurred less than 2 years prior to entry improved more than did those who had arthritis for a longer period. In addition, those with polyarticular involvement at baseline improved more than did patients with mild disease. However, these relationships were observed in both the auranofin- and placebo-treated groups, and again, there were no significant intergroup differences. Diarrhea was the most common adverse effect of auranofin. We conclude that the clinical efficacy of auranofin is modestly higher than that of placebo in the treatment of JRA, as evidenced by the consistent trends observed in the data. However, the magnitude of the individual intergroup differences is not statistically significant. Auranofin appears to be very safe in children with JRA.

Low-dose methotrexate compared with auranofin in adult rheumatoid arthritis. A thirty-six-week, double-blind trial

Weekly treatment with low-dose oral methotrexate (MTX) was compared with daily auranofin (AUR) treatment in a 36-week double-blind, randomized, multicenter study of 281 patients with active, adult-onset rheumatoid arthritis. Both treatment groups showed significant improvement by the usual measures of clinical efficacy. The response with MTX occurred earlier and was consistently greater than that with AUR. An intent-to-treat analysis showed significantly greater improvement (P less than 0.01) with MTX for painful and swollen joint counts and physician and patient global assessments of disease activity. Adverse reactions were reported more frequently in the AUR group, and more AUR-treated patients were withdrawn from the study because of toxicity. MTX was thus more effective and better tolerated than AUR in this study.

Effect of auranofin on eicosanoids and protein kinase C in human neutrophils

Auranofin (AF), a lipophilic chrysotherapeutic agent, was investigated for its effect on the formation of lipoxygenase products and the activity of protein kinase C in human neutrophils. We have previously shown that inhibition of LTB4 formation by 5-lipoxygenase (5-LO) inhibitors is intimately associated with a marked increased in 15-HETE in excess of arachidonic acid. The calcium- and phospholipid-dependent protein kinase, protein kinase C, is activated in FMLP- and A23187-stimulated neutrophils, is hypothesized to stimulate superoxide generation, and plays an essential role in eicosanoid production. AF dose-dependently inhibited the generation of leukotriene B4(LTB4) in FMLP-stimulated neutrophils, the ID50 was approximately 4.5 micrograms/ml. Unlike known 5-LO inhibitors, AF did not enhance the production of 15-HETE. In neutrophils stimulated with the calcium ionophore, A23187, AF did not inhibit the generation of LTB4 nor did AF change the 15-HETE levels. AF inhibited superoxide generation in FMLP-stimulated neutrophils dose-dependently, but did not change the activation of protein kinase C in the cells. We therefore conclude, that AF inhibition of LTB4 production in neutrophils is different from 5-lipoxygenase inhibitors and is elicited at a step distal to protein kinase C activation.

Stimulatory effects of anti-rheumatic drugs on human neutrophil functions

Auranofin (AF), D-penicillamine (D-pen) and thiola are prescribed as disease-modifying drugs in the treatment of rheumatoid arthritis (RA). We have shown here that auranofin, 10(-8) to 10(-6) M, D-penicillamine, 10(-6) to 10(-3) M, thiola, 10(-7) to 10(-3) M, and the tripeptide thiol, glutathione, 10(-6) to 10(-3) M, enhanced f-met-leu-phe-induced lysosomal enzyme release and the phagocytic uptake of bacteria by up to 40%. The previously reported inhibitory effects of AF were only observed at concentrations in excess of those likely to be available to effector cells in vivo. The stimulatory effects of thiola and D-pen occurred at concentrations likely to be available to effector cells in vivo and, therefore, may be of greater clinical relevance. There is evidence that the drugs used in this study exert their effects via a thiol moiety and their therapeutic effect is preceded by an elevation of intracellular thiol levels.

A modified mouse air pouch model for evaluating the effects of compounds on granuloma induced cartilage degradation

1. Employing rat femoral head cartilage implanted in a 6 day old mouse air pouch, the effects of inflammatory stimuli (i.e. cotton pellets, carrageenan, zymosan) on the loss of proteoglycan and collagen and granuloma formation have been studied. 2. Wrapping of the cartilage in cotton resulted in granuloma formation with accelerated loss of proteoglycan and collagen over the 14 day implantation period. The amount of loss increased with increasing weight of cotton. 3. The effects of different classes of anti-rheumatic drugs on granuloma formation and proteoglycan and collagen loss from cotton wrapped femoral head cartilage in the mouse air pouch have been studied. 4. Non-steroidal anti-inflammatory drugs (NSAIDs) had no influence on granuloma formation, but in general accelerated the rates of proteoglycan and collagen loss. 5. Dexamethasone and prednisolone significantly reduced granuloma formation and had a marked protective effect on cartilage breakdown. 6. Of the slow acting anti-rheumatic drugs examined, only gold sodium thiomalate (GSTM) and dapsone significantly decreased cartilage loss, with an accompanying modest decrease in granuloma formation. 7. The immunosuppressants cyclophosphamide and methotrexate, but not azathioprine, reduced cartilage degradation, but had no effect on granuloma formation. 8. The results for the different classes of anti-inflammatory and anti-rheumatic drugs are discussed in relation to their effects in other animal models and their reported therapeutic activities in man. It is concluded that the mouse air pouch method as described offers advantages as an animal model over existing procedures to predict therapeutic efficacy in man.

Auranofin and gold sodium thiomalate in the treatment of rheumatoid arthritis: a one-year, double-blind, comparative multicenter study

In a 48-week, double-blind trial, 122 patients were randomly assigned to treatment with auranofin (60) and gold sodium thiomalate (GST) (62) at five centers. Both groups showed significant improvement (P less than 0.05) from baseline in parameters of disease activity. Results of the covariance analysis for all patients who completed the trial showed no significant differences (P less than 0.05) in efficacy between the two groups. The proportions of patients showing 50% or greater improvement in tender joints, swollen joints, activity index, severity of pain, general health rating, and erythrocyte sedimentation rate (ESR) were similar for both auranofin-treated and GST-treated patients who completed the 48-week trial. When all patients who entered the trial were evaluated, a slightly greater proportion of patients on auranofin had improved. Diarrhea occurred more frequently with auranofin (32%) compared to GST (19%), whereas rash and pruritus were twice as common in those patients treated with GST compared to those treated with auranofin. The withdrawal rate due to adverse reactions was 10% for auranofin vs 26% for GST. It was concluded that the efficacy of auranofin was comparable to that of injectable gold and was better tolerated, as evidenced by the lower withdrawal rate from adverse events for the auranofin patients.

Rheumatoid arthritis: can the long-term outcome be altered?

Although several agents (for example, intramuscularly administered gold, auranofin, D-penicillamine, hydroxychloroquine, and methotrexate) are of clinical benefit in the management of rheumatoid arthritis (RA), their effect on the long-term outcome of the disease is controversial. Assessment of the influence of therapeutic interventions in RA is difficult because the natural history of the disease remains poorly defined and unpredictable, and neither the traditional clinical and laboratory measurements of inflammation nor radiographic analyses of progression of joint destruction provide an accurate estimate of the long-term outcome of RA. Furthermore, there is little evidence that second-line agents yield benefits beyond 3 years. Therefore, adequately tested comprehensive measures should be used in large, long-term, multicenter controlled clinical trials to determine whether the long-term outcome of RA can be altered.

Effect of auranofin and sodium aurothiomalate on interleukin-1 production from human monocytes in vitro

The continuous presence of Auranofin (AF), 1.0 microgram/ml and above, or sodium aurothiomalate (GST), 2.0 micrograms/ml and above, inhibited the phytohaemagglutinin-induced proliferation of monocyte-depleted mononuclear cells. Preincubation of monocytes (M phi) with AF, 1.0 microgram/ml, caused a minor increase in the co-stimulatory effect of LPS-induced M phi-culture supernatants, whereas preincubation with AF 2.5 micrograms/ml and above resulted in a dose-dependent decrease in production of the co-stimulatory factor--probably interleukin-1 (IL-1). This inhibition is not due to decreased M phi viability, production of suppressive substances, or drug interference with the IL-1 test assays. A similar preincubation with GST up to 100 micrograms/ml had no effect on IL-1 production, nor did preincubation with thioglucopyranose, triethylphosphine or chloroauric acid, the three molecular sub-components of AF. The inhibitory effect of AF on the production of IL-1--as well as other co-stimulatory monokines--and on lymphocyte proliferation might explain the anti-inflammatory and disease-modifying effect of the drug.

Adverse reactions with oral and parenteral gold preparations

Auranofin (triethylphosphine gold), an oral gold preparation, has recently been made available, and along with injectable gold preparations, is of therapeutic value for rheumatoid arthritis. Serious gold toxicity is uncommon, and drug-related deaths rare. Many potential adverse reactions are similar, including dermatitis, stomatitis, thrombocytopenia, leucopenia, and proteinuria, generally with increased incidence in the injectable gold-treated patients. Oral gold is associated with benign lower gastrointestinal side effects, including diarrhoea, loose stools and abdominal cramps that are often dose-related and resolve spontaneously. The incidence of severe reactions such as thrombocytopenia, aplastic anaemia and exfoliative dermatitis is lower with oral gold than injectable preparations, and contributes to a superior risk-benefit ratio. The treatment of gold toxicity depends on the type and extent of organ involvement.

Cellular interactions of auranofin and a related gold complex with RAW 264.7 macrophages

Auranofin (AF) is an orally active chrysotherapeutic agent whose precise mechanism of action with its putative target cell, the macrophage, is not known. In a previous paper, we described a sequential thiol exchange mechanism that explained auranofin's molecular mechanism of interaction with RAW 264.7 cells. To further understand the mode of action of AF and to test the validity of the thiol exchange model, we have continued to study the interactions with macrophages of AF and a related gold complex, triethylphosphine gold chloride (TEPG). Evaluation of the effects of AF and TEPG on RAW 264.7 cells demonstrated that: more gold from TEPG than AF associated with cells over time and with a variety of concentrations; and cellular association of AF and TEPG was temperature dependent. The energy of activation for cell association, the rate-limiting step in the thiol exchange process, was lower for TEPG than AF; cellular association and uptake of both compounds did not require metabolic energy; and efflux of both AF and TEPG was time, temperature, and thiol dependent. Based on these and previous data, we conclude that sequential thiol exchange may be a generic phenomenon for cellular uptake and distribution of thiol reactive gold compounds and that the rate-limiting step is the exchange of either tetraacetylthioglucose (TATG) or chloride for a membrane-localized sulfhydryl group.

Auranofin therapy and quality of life in patients with rheumatoid arthritis. Results of a multicenter trial

In a six-month, randomized, double-blind study at 14 centers, auranofin (3 mg twice daily) was compared with placebo in the treatment of patients with classic or definite rheumatoid arthritis. All patients had unremitting disease for at least the previous six months and at least three months of therapy with nonsteroidal anti-inflammatory drugs (NSAIDs). NSAIDs, oral steroids, and analgesics were allowed throughout the trial. Efficacy was analyzed in 154 patients who received auranofin and 149 who received placebo. To reflect an expanded view of outcome assessment, the measures used included some 20 nontraditional measures of functional performance, pain, global impression, and utility (worth or value) in addition to five standard clinical measures of rheumatoid synovitis (e.g., number of tender joints). The nontraditional measures were mainly in the form of structured questionnaires administered by trained interviewers. To minimize the statistical problem of multiple comparisons, most of the measures were grouped into four composites--clinical (standard measures), functional, global, and pain--and the treatment effect for each composite was tested at the 0.0125 level of significance. Auranofin was superior to placebo in the clinical (p = 0.003), functional (p = 0.001), and global (p = 0.007) composites and trended similarly in the pain composite (p = 0.021). Individual measures within the composites consistently favored auranofin. Other measures, not part of the composites, also favored auranofin, including a patient utility measure designed for this study, the PUMS (p = 0.002). Results confirm the hypothesis that the favorable effect of auranofin on clinical synovitis is accompanied by improvements across a range of outcomes relevant to the patient's quality of life.

Interactions of gold coordination complexes with DNA

The interactions of certain gold(I) and gold(III) complexes with isolated plasmid pBR322 DNA were defined and compared to those of cis-diamminedichloroplatinum(II), CDDP, using an agarose gel electrophoresis assay. Trichloro(pyridine)gold(III) appeared to bind to DNA as evidenced by its ability to produce dose-dependent changes in the electrophoretic mobilities of closed circular, supercoiled, closed circular, relaxed, and open circular plasmid DNAs. These effects suggest that the gold containing complex induces conformational changes in the plasmid as a result of the compound binding to the DNA and the subsequent unwinding of the double helix and shorting of the DNA. Auranofin [(2,3,4,6-tetra-O-acetyl-1-thio-beta-D-glucopyranosato-S)-triethyl phosphine gold(I)] did not appear to interact with DNA under any conditions. However, its analog chloro(triethylphosphine) gold(I) interacted with DNA at pH 9.5 in borate buffer and produced electrophoretic mobility changes in pBR322 DNA which were different from those produced by the gold(III) complexes that were evaluated. Binding of chloro(triethylphosphine) gold(I) was inhibited by the co-addition of the thiosugar portion of auranofin suggesting preferential binding of the gold moiety to thiosugar, which results in the production of auranofin (or a sugar containing) gold complex and inhibition of gold binding to DNA. The interactions of a number of gold compounds with DNA were also evidenced by their abilities to inhibit the binding of ethidium bromide to DNA. The results from these studies indicate that: gold containing complexes can bind to, and produce conformational changes in, DNA; gold(I) and gold(III) complexes may interact with DNA via different chemical mechanisms to produce different conformational changes in DNA; and certain coordinating ligands in gold complexes (e.g. Cl, Br and SCN) can be exchanged for binding sites on DNA by gold.

Reactions of triethylphosphine gold(I) complexes with heme proteins: novel spin-state changes in cytochrome b562, myoglobin, and hemoglobin

Reactions of bacterial Fe(III) cyt b562, HbO2, met Hb and met Mb with Et3PAuCl and Et3PAuNO3 (and some related complexes) have been investigated by electronic absorption and EPR and NMR spectroscopy. Except for met Hb, which denatured, the products were novel high-spin Fe(III) heme proteins. The reactions of cyt b562 and Mb were reversible. Two distinct kinetic steps were observed in the autoxidation of HbO2 and MbO2. These may involve the liberation of superoxide. Autoxidation of HbO2 occurred more rapidly than that of MbO2. The kinetics of the spin-state change of cyt b562 were too fast to measure by conventional (spectrophotometric) methods. The reaction of Et3PAuCl with HbO2 was not blocked by N-ethylmaleimide. The reactions are discussed in terms of attack by Et3PAu+ on histidine residues in the hydrophobic haem pockets of the proteins.

Oral gold in arthritis

There are few drugs available with purported disease-modifying or healing effects in rheumatoid arthritis. The two agents that have gathered the most support in favor of these effects are parenteral gold and cyclophosphamide; however, both can produce intolerable toxicity. A new oral gold compound (auranofin; Ridaura) is being investigated in rheumatoid arthritis. Available studies suggest that auranofin may be slightly less effective than parenteral gold, but is significantly less toxic, the main side effect being diarrhea. There is evidence to suggest auranofin slows radiologic progression of the disease, but further studies are indicated. If further studies demonstrate a healing effect of the drug, comparable with data suggesting this effect for parenteral gold, auranofin may become a first-line agent in rheumatoid arthritis.