Digestive Disease Week 2008 Report: Part 2

Digestive Disease Week (DDW) is considered the largest and most prestigious meeting in the world for the gastrointestinal professional. Each year, DDW features leading researchers and clinicians in the field of gastrointestinal medicine discussing the latest research. Part 2 of a report based on a selection of key sessions in DDW 2008 has just been released.

Emerging therapies for irritable bowel syndrome

Therapy for irritable bowel syndrome (IBS) has been limited. Dr William Shey reviewed both current treatment approaches and clinical trials for diarrhoea and constipation predominant IBS.

The main therapeutic agent or diarrhoea predominant IBS still in (restricted) use in the USA (not available in Australia) is Alosteron. It is only effective in women with severe diarrhoea predominant IBS. Other agents that are currently undergoing clinical trials include drugs which reduce chlorine secretion.

Therapies for constipation predominant IBS appear to be more evolved. Tegaserod provided some potential, but was withdrawn from the market due to complications. MD-1100 acetate (Linaclotide) is currently undergoing clinical trials. Renzapride, a partial 5HT3 antagonist and a full 5HT4 agonist, is in development. Chloride channel stimulants such as lubiprostone (Amitiza) have now become available in the USA. Finally, subcutaneous methylnaltrexone (Relistor), a mu-opioid-receptor antagonist, is approved for use in Europe and Canada for the management of opioid induced constipation.

Clinicians will need to have an understanding of these drugs as they will likely become available over the next few years.

Radiofrequency ablation of Barrett’s oesophagus with dysplasia

The future utility of radiofrequency ablation (RFA) in Barrett’s oesophagus depends on its ability to ablate dysplasia. DDW 2008 saw the release of the interim results of some of the major studies assessing this treatment modality.

Three quarters of RFA subjects in the Ablation of Intestinal Metaplasia (AIM) Dysplasia Trial of RFA for dysplastic Barrett’s oesophagus achieved complete clearance of intestinal metaplasia, compared to none of the sham treatment subjects.

Data from the first European multicentre trial suggests that stepwise circumferential and focal RFA of Barrett’s oesophagus with early neoplasia (with or without endoscopic resection) is highly effective for the complete eradication of Barrett’s oesophagus and associated dysplasia without serious adverse events.

Other studies concluded that RFA preserves oesophageal motility, lumen size and compliance. RFA has so far been associated with significantly fewer strictures compared to photodynamic therapy.

Third Eye Retroscope

The Avantis ‘Third Eye’ Retroscope System was demonstrated at DDW. This is a disposable device that provides an additional view to reveal polyps, cancers and other lesions that might be hidden from the lens of the traditional forward-viewing colonoscope. A multicentre study found that, in combination with a standard colonoscope, the Third Eye Retroscope detected more polyps and adenomas compared to the colonoscope alone.