Results from a Phase 1/2 trial of BB2603, a terbinafine-based topical nano-formulation, in onychomycosis and tinea pedis.

BB2603 is a nano-formulation of the antifungal drug terbinafine with the polymer polyhexamethylene biguanide (PHMB) as an excipient to enhance solubility and drug delivery to skin and nails. BB2603 is delivered topically using a low-velocity spray. It is being developed in different strength formulations for the treatment of fungal infections of the nail and skin, including onychomycosis and tinea pedis, with BB2603-1 (0.01% terbinafine) tested in the present trial. The aim of this study was to assess systemic exposure, safety and tolerability of BB2603-1 compared with Lamisil® AT 1% spray and BB2603-1 vehicle control in onychomycosis and tinea pedis. Preliminary mycological and clinical activity were also investigated. This was a single-centre Phase 1/2, randomised, partially blinded, active- and vehicle-controlled, parallel-group trial in 46 subjects with onychomycosis associated with tinea pedis. Part 1 investigated BB2603-1 versus Lamisil AT 1% spray and BB2603-1 vehicle (4 weeks treatment). Part 2 investigated BB2603-1 versus BB2603-1 vehicle (additional 48 weeks treatment). No measurable systemic exposure of terbinafine was shown over 52 weeks of treatment with BB2603-1. BB2603-1 had an excellent safety and tolerability profile with no drug-related safety findings and no evidence of skin sensitisation. BB2603-1 showed preliminary evidence of anti-dermatophyte activity, demonstrated by a reduction in dermatophyte positive cultures and a reduction in microscopic evidence of dermatophytes. The pharmacokinetic, safety and efficacy data from this trial support further development of the topical terbinafine-based nano-formulation BB2603 in fungal infections of the skin and nail, including onychomycosis and tinea pedis.

Surveying bovine digital dermatitis and non-healing bovine foot lesions for the presence of Fusobacterium necrophorum, Porphyromonas endodontalis and Treponema pallidum.

BACKGROUND: Non-healing bovine foot lesions, including non-healing white line disease, non-healing sole ulcer and toe necrosis, are an increasingly important cause of chronic lameness that are poorly responsive to treatment. Recent studies have demonstrated a high-level association between these non-healing lesions and the Treponema phylogroups implicated in bovine digital dermatitis (BDD). However, a polymicrobial aetiology involving other gram-stain-negative anaerobes is suspected. METHODS: A PCR-based bacteriological survey of uncomplicated BDD lesions (n=10) and non-healing bovine foot lesions (n=10) targeting Fusobacterium necrophorum, Porphyromonas endodontalis, Dichelobacter nodosus and Treponema pallidum/T. paraluiscuniculi was performed. RESULTS: P. endodontalis DNA was detected in 80.0% of the non-healing lesion biopsies (p=<0.001) but was entirely absent from uncomplicated BDD lesion biopsies. When compared to the BDD lesions, F. necrophorum was detected at a higher frequency in the non-healing lesions (33.3% vs 70.0%, respectively), whereas D. nodosus was detected at a lower frequency (55.5% vs 20.0%, respectively). Conversely, T. pallidum/T. paraluiscuniculi DNA was not detected in either lesion type. CONCLUSION: The data from this pilot study suggest that P. endodontalis and F. necrophorum should be further investigated as potential aetiological agents of non-healing bovine foot lesions. A failure to detect syphilis treponemes in either lesion type is reassuring given the potential public health implications such an infection would present.

Genetic engineering of Nicotiana tabacum for reduced nornicotine content.

UNLABELLED: Nornicotine is an undesirable secondary alkaloid in cultivated tobacco, because it serves as a precursor to N'-nitrosonornicotine (NNN), a tobacco-specific nitrosamine with suspected carcinogenic properties. Nornicotine is produced through the oxidative N-demethylation of nicotine by a nicotine N-demethylase enzyme during the senescence and curing of tobacco leaves. While the nornicotine content of most commercial burley tobacco is low, a process termed "conversion" can bestow considerably increased nornicotine levels in a portion of the plants within the population. Previously, we isolated a nicotine N-demethylase gene, designated CYP82E4, and demonstrated that RNAi-induced silencing of CYP82E4 and its close homologues is an effective means for suppressing nicotine to nornicotine conversion. In this study, we used real-time polymerase chain reaction to confirm the central role of CYP82E4 in nicotine N-demethylation by demonstrating that the transcript accumulation of CYP82E4 is enhanced as much as 80-fold in converter vs nonconverter tobacco. We also show the design of an optimized RNAi construct (82E4Ri298) that suppressed nicotine to nornicotine conversion from 98% to as low as 0.8% in a strong converter tobacco line, a rate of nornicotine production that is about 3.6-fold lower than typically detected in commercial varieties. Southern blot analysis showed that a single copy of the RNAi transgene was as effective in suppressing nornicotine accumulation as multiple copies. Greenhouse-grown transgenic plants transformed with the RNAi construct were morphologically indistinguishable from the empty vector or wild-type controls. These results demonstrate that the genetic transformation of tobacco with the 82E4Ri298 construct is an effective strategy for reducing nornicotine and ultimately NNN levels in tobacco. KEYWORDS: Alkaloid; cytochrome P450; gene silencing; nicotine N-demethylase; N'-nitrosonornicotine; plant genetic engineering; metabolic engineering; Nicotiana tabacum L.; real-time PCR; RNA interference; tobacco-specific nitrosamines.