Event - Auxilium hoping the FDA will hand it approval for Xiaflex

Analysis

After a false alarm back in August due to FDA timetable issues, Auxilium Pharmaceuticals in now facing the very real prospect of its lead and most valuable pipeline candidate passing an advisory committee next week and getting US approval by the end of the year.

If it does make it the fact that Xiaflex, a treatment for Dupuytren’s contracture, has fast track status means that it could be on the market before the end of the year. Dupuytren’s contracture is a painful twisting of the hand into a claw due to the shortening and hardening of tendons and is often a complication of diabetes. Given that at present the only treatment is surgery analysts are expecting that the FDA will look positively on Xiaflex, which only requires one to three injections into the hand.

Safety first

Despite some worries earlier in the year about hypersensitivity side effects, issues from the advisory committee are not anticipated and many believe Xiaflex will win approval; expectations that are reflected in the share price that has not moved much in the last few weeks. The fact that the main ingredient of the drug, collagenase, is already used in a variety of treatments including ulcers and severe burns, might be buoying hopes of a smooth passage.

Also helping the cause is that Auxilium recently announced that it had started enrolling a long-term study for Dupuytren’s contracture involving patients in the previous phase III trial, in an effort to look at long term clinical outcomes and also to gather safety data up to 5 years post treatment.

This study has not been requested by the FDA, but by doing this the company might be trying to head the regulator off at the pass, just in case it does decided to request a long-term safety study or a risk evaluation and mitigation strategy (REMS), which should in turn help the group circumvent some of the tricky labeling discussions that some analysts have predicted.

Gearing up for launch

Certainly the group, which is marketing the drug itself in the US, is confident of launch and has already started identifying the key opinion leaders in Dupuytren’s, issued contracts to sales staff and has set up a call centre to deal with medical questions and safety reporting. It is thought that Auxilium will be initially starting with a sales force of between 75-100 reps, targeting surgeons.

Auxilium definitely does not need any hiccups with Xiaflex's approval. The drug is the biggest growth driver at the company and Auxilium’s longer term success is hanging on it. Consensus forecasts from EvaluatePharma show that by 2014 the drug is estimated to generate combined sales and royalties of $474m.

The drug is also being developed in Peyronie’s disease, which causes curvature of the penis, and phase IIb results are expected by the end of the fourth quarter. Analysts have also based at least some of their sales forecasts on the much wider and lucrative market of frozen shoulder.

Another group which believes in the potential of Xiaflex is Pfizer, the group signed a $485m licensing deal for European rights in December 2008, giving Auxilium a very welcome $75m upfront fee (Auxilium hits the jackpot with Pfizer deal, December 18, 2008). Pfizer is expected to file the drug for approval in Dupuytren’s in 2010 and could also conduct its own Peyronie’s study, an event that might depend on the outcome of Auxilum’s US trials.

Valuable product

The importance of the success of Xiaflex to Auxilium is further underlined by the reality that the only other marketed product in the pipeline is Testim. The testosterone replacement product earlier this week narrowly escaped serious competition when Endo announced that the FDA had extended the review period for its long-acting once monthly testosterone injection, Nebido, by three months to give it more time to review the application and Endo’s REMS.

But analysts are still forecasting a decline in sales of Testim from 2011 onwards following the filing of a generic challenge by Upsher-Smith Laboratories last October. With the expectation of a copycat product on the market by April 2011 sales forecasts for 2012 have fallen by $67m in last 12 months to $176m. Therefore with little else in the locker, if Xiaflex fails to get approval, Auxilium will be hit hard.

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