Expert opinion on emerging urate-lowering therapies

INTRODUCTION

There has been a resurgence in gout therapeutics in the last decade, not only for the management of gout flares, but also for the treatment of hyperuricemia. This editorial summarizes new, emerging therapies for people with gout. Areas covered: We review several new therapies for gout, including those that are focused on lowering serum urate (levotofisopam, ulodesine, verinurad, merbarone, KUX-1151, UR-1102, FYU-981, SEL-212), or treating gout flares (canakinumab, bucillamine) or both (arhalofenate, diacerein). Expert opinion: Among therapies with both urate lowering and anti-inflammatory action, arhalofenate seems promising, but more data are needed. Examining therapies aimed at treating gout flares [anti-inflammatory action], bucillamine has some potential, but more data and Phase III studies are needed, to better understand its efficacy and safety. Among the urate-lowering therapies (ULTs), verinurad seems to be the most promising, while levotofisopam and ulodesine require more data. A uricase-replacement therapy with improved immune reaction (SLE-212) is in a Phase II trial. A number of ULTs including KUX-1151, UR-1102 and FYU-981 are in early development and more will be known once initial data and studies are published.

Hyperplasia of Lymphoid Follicles and Lymphangiectasia in the Parietal Pleura in Bucillamine-induced Yellow Nail Syndrome

Yellow nail syndrome (YNS) pleurisy is often difficult to control, and pathological examinations have rarely been reported. We herein report a case of bucillamine-induced YNS in which histopathology of the parietal pleura revealed hyperplasia of the lymphoid follicles and lymphangiectasia. Even after the discontinuation of bucillamine, the pleurisy and lymphedema showed no change. Based on the histopathological findings showing similarity to rheumatoid pleurisy, we administered corticosteroid treatments, and both the pleurisy and lymphedema improved. The findings in the present case suggest that, in bucillamine-induced YNS, pleurisy may be related to inflammation caused by rheumatoid arthritis in addition to abnormalities in lymphatic vessels.

HLA-DRB1*08:02 Is Associated with Bucillamine-Induced Proteinuria in Japanese Rheumatoid Arthritis Patients

BACKGROUND

Drug-induced proteinuria can occur in rheumatoid arthritis (RA) patients treated with d-penicillamine, gold salts, or bucillamine (Buc), and represents a drug hypersensitivity reaction. Striking associations of human leukocyte antigen (HLA) alleles with adverse reactions have recently been reported for many drugs.

METHODS

We investigated the association of HLA class II with Buc-induced proteinuria (BI-Pro) in 485 Japanese RA patients treated with Buc, of whom 25 had developed BI-Pro.

RESULTS AND CONCLUSION

This preliminary study showed a highly significant association of DRB1*08:02 with BI-Pro (P = 1.09 × 10⁻⁶, corrected P [Pc] = 1.96 × 10⁻⁵, odds ratio [OR] 25.17, 95% confidence interval [CI] 7.98–79.38). DQB1*04:02 was also significantly associated with increased risk of BI-Pro (P = 2.44 × 10⁻⁵, Pc = 2.69 × 10⁻⁴, OR 10.35, 95%CI 3.99–26.83). These findings provide useful information for promoting personalized medicine for RA.

Bucillamine-induced pemphigus vulgaris in a patient with rheumatoid arthritis and polymyositis overlap syndrome

Bucillamine is a disease modifying anti-rheumatic drug, structurally similar to D-penicillamine. Although D-penicillamine-induced pemphigus has been not infrequently demonstrated, pemphigus associated with bucillamine was rarely reported. We describe a patient complicating pemphigus vulgaris after bucillamine treatment in rheumatoid arthritis (RA) and polymyositis (PM) overlap syndrome. PM and RA overlap syndrome was diagnosed three years ago and bucillamine was administrated for 20 months. Skin lesions including erythematous flaccid blisters on her chest, axillae, and back were occurred and were compatible with pemphigus vulgaris by typical pathology. Withdrawal from bucillamine and prednisolone treatment made rapid improvement of pemphigus lesions.

Inhibitory mechanism of vascular endothelial growth factor (VEGF) by bucillamine

1. Vascular endothelial growth factor (VEGF) plays an important role in the neovascularization of ischaemic retinal diseases such as proliferative diabetic retinopathy. We determined that bucillamine, an anti-rheumatic drug, inhibits the VEGF production induced by hypoxia in bovine retinal microcapillary endothelial cells (BREC). To further clarify the inhibitory mechanism, we investigated the possible mechanism by which bucillamine exerts this inhibitory effect. 2. Bucillamine (100 micro M) decreased the hypoxia-induced increase of VEGF mRNA by 54.5% (P<0.001). Bucillamine (100 micro M) reduced the hypoxia-induced VEGF content in culture media by 29.0% (P<0.001), while monosulfydryl drugs, N-acetylcysteine and D-penicillamine, did not. 3. Bucillamine (100 micro M) did not affect VEGF mRNA half-life (hypoxia, 4.3 h; hypoxia+bucillamine, 3.9 h; normoxia, 2.7 h; normoxia+bucillamine, 2.7 h). 4. Reporter gene studies revealed that bucillamine reduced transcriptional activity in the 5'-flanking region of the VEGF gene by 74.0%. Hypoxia stimulated binding activity of BREC nuclear protein to a hypoxia responsive element (HRE), which was decreased by bucillamine. 5. Bucillamine inhibited hypoxic-induction of HIF-1alpha mRNA by 73.1% (P<0.001). Bucillamine also inhibited spontaneous VEGF mRNA expression by 26.6%. Furthermore, it inhibited activity of VEGF promoter and decreased binding activity to Sp1 and HRE, but did not alter AP1 and AP2 activity in normoxia. 6. These data suggest that bucillamine inhibits hypoxic induction of VEGF through inhibition of HIF-1 induction and binding activity in BREC. Bucillamine also inhibits the spontaneous expression of VEGF mRNA by its effect on Sp1 and HRE binding.

Effects of bucillamine and N-acetyl-L-cysteine on cytokine production and collagen-induced arthritis (CIA)

We investigated the effects of bucillamine and N-acetyl-L-cysteine (NAC) on cytokine production and CIA. Bucillamine and NAC inhibited NF-kappaB activation and tumour necrosis factor-alpha (TNF-alpha) mRNA expression in human monocytic leukaemia cell line THP-1, and cytokine production from monocyte cell lines at concentrations >10-3 M. They also inhibited cytokine production and CIA in mice at a dose of 500 mg/kg. These results suggest that NF-kappaB inhibitors such as bucillamine and NAC may inhibit cytokine-related diseases, including arthritis.