Safe, long-term hepatic expression of anti-HCV shRNA in a nonhuman primate model

The hepatitis C virus (HCV) chronically infects 2% of the world population and effective treatment is limited by long duration and significant side-effects. Here, we describe a novel drug, intended as a “single-shot ” therapy, which expresses three short hairpin RNAs (shRNAs) that simultaneously target multiple conserved regions of the HCV genome as confirmed in vitro by knockdown of an HCV replicon system. Using a recombinant adeno-associated virus (AAV) serotype 8 vector for delivery, comprehensive transduction of hepatocytes was achieved in vivo in a nonhuman primate (NHP) model following a single intravenous injection. However, dose ranging studies performed in 13 NHP resulted in high-expression levels of shRNA from wild-type (wt) Pol III promoters and dose-dependent hepatocellular toxicity, the first demonstration of shRNA-related toxicity in primates, establishing that the hepatotoxicity arises from highly conserved features of the RNA interference (RNAi) pathway. In the second generation drug, each promoter was re-engineered to reduce shRNA transcription to levels that circumvent toxicity but still inhibit replicon activity. In vivo testing of this modified construct in 18 NHPs showed conservation of hepatocyte transduction but complete elimination of hepatotoxicity, even with sustained shRNA expression for 50 days. These data support progression to a clinical study for treatment of HCV infection

Treatment strategies for tics in Tourette syndrome

Tourette syndrome (TS) is a chronic neurodevelopmental disorder characterized by tics: repetitive, involuntary movements and vocalizations. These symptoms can have a significant impact on patients’ daily functioning across many domains. Tics tend to be most severe in child and adolescent sufferers, so their presence has the potential to impact a period of life that is both critical for learning and is often associated with the experience of greater social tension and self-consciousness than adulthood. Furthermore, control over tics that lead to physical impairment or self-injurious behaviour is of vital importance in maintaining health and quality of life. There are numerous complicating factors in the prescription of treatment for tics, due to both the side effects associated with alleviating agents and patient characteristics, such as age and comorbid conditions. This review summarizes literature pertaining to the efficacy and safety of both traditionally prescribed and more modern medications. We also discuss the merits of behavioural and surgical techniques and highlight newer emerging treatments. Although treatment response is to some extent variable, there are a number of agents that are clearly useful as first-line treatments for TS. Other interventions may be of most benefit to patients exhibiting refractory tics or more specific symptom profiles