GSK's migraine drug blocked for second time in US

The FDA has for the second time delayed approval of GlaxoSmithKline's (GSK) migraine drug Trexima, its replacement for Imitrex which goes off-patent in Q4 2008.

The FDA letter is the second sent to GSK for Trexima, with the first received in June 2006. The FDA highlighted cardiovascular safety issues, so GSK submitted more safety data from clinical and pre-clinical data to successfully allay these concerns.

The second letter questions observed geno-toxicity in one of the GSK's pre-clinical studies.

Imitrex racked up GBP 711m (USD 1.5bn) in FY06 sales.

GSK is partnering with US-based Pozen, which is providing its MT 400 technology to combine sumatriptan and naproxen in a single Trexima tablet.
Pozen is responsible for the preclinical, clinical, and regulatory development activities, while GSK is responsible for formulation development, manufacturing and commercialisation. The Trexima NDA was submitted to the FDA in August 2005.

The FDA action has caused concern among analysts who say they do not understand if the FDA is requesting GSK to do a further study or simply wants to discuss further the genotoxicity issue. Whatever the reason, the further delay can only add to GSK's current financial worries.

With increasing pressure on the FDA to highlight drug safety, the Trexima delay is just one of many high-profile agency actions in recent weeks.

Novartis's IBS drug Zelnorm (tegaserod), Wyeth's non-hormonal menopause treatment Pristiq(desvenlafaxine) and the safety alerts over Avandia (roseglitazone) and anaemia drugs have all been hitting the headlines.

For Pristiq, the FDA asked Wyeth to complete an additional year-long trial to examine cardiac and liver toxicity, which could delay the drug until Q1/Q2 2009. Zelnorm was taken off the US market back in March over links to cardiovascular side-effects. It has since been given a limited route back into the market with many strict conditions.

Also, Medicare reimbursement for anaemia drugs used in certain types of cancers has been restricted, leaving Johnson & Johnson and Amgen gasping as sales of those drugs dropped markedly in both firm's Q2 FY07 financials.

For H1 FY07, Pozen reported a net loss of USD 5.9m, or USD 0.20 loss per share, compared with a net loss of USD 14.9m, or USD 0.51 loss per share, for the same period in 2006.

Revenue of USD 19.6 million was recorded in H1 FY07, compared with USD 3.1m for the same period in 2006. Operating expenses were USD 27.1m, compared with USD 18.9m.