Affymax's fight begins as Epogen contender finally wins approval

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Approval has been won and now the biggest challenge confronts Affymax – carving out a share for its anaemia treatment Omontys from Amgen, which has effectively controlled the market for 20 years.

The product’s once-monthly dosing will stand it in good stead, compared to the one to three times a week required for Amgen’s Epogen. However the incumbent can be expected to make the most of Omontys’ restricted label and safety signals that emerged in clinical trials.

Green light expected

Affymax shares fell almost 6% to $13.48 in early trade today, in what appears to be a classic case of selling on the news. The stock ceased trading at a 21-month high of $14.31 yesterday after being suspended ahead of the announcement, having more than doubled in value so far this year.

A green light was widely expected for the product, generically called peginesatide (Adcom puts Affymax one step closer to market, December 8, 2011). As predicted the FDA approved Omontys for use only in a dialysis setting, ruling out use before a patient with kidney disease requires mechanical blood cleaning.

Affymax will co-promote with Takeda in the US. Consensus data from EvaluatePharma, collected prior to the approval decision, show analysts tracking the Japanese drug maker reckon its market sales could reach $94m this year, rising to $520m by 2016. Affymax analysts have been modelling alliance revenue of $16m this year, rising to $185m in 2016.

On a conference call yesterday Affymax executives said the wholesale price of the product is likely to be similar to Amgen’s Epogen, which first reached the market in 1989 and generated sales of $2bn last year. With patents protecting Epogen due to expire in 2013, many believe the product could be among the first biologics to meet biosimilar competition in the US, although question marks over the path to market mean when and how this might happen is far from certain (Development costs will constrain biosimilar entry, March 23, 2012).

Fight is on

The first real competition for Epogen is another uncomfortable development for Amgen, the approval marking the latest chink in the armour of a hugely profitable franchise for the company.

Analysts at UBS who track Amgen said they had already factored in Omontys competition, and predict its market share growing from 2% in 2012 to double digits by 2018.

Efforts to restrict the dose and reduce usage of Epo products in the wake of safety scares mean demand for these products is already in decline; supply contracts struck with dialysis providers in the last year or so represent Amgen’s efforts to lock up the market in the face of falling sales and the threat of competition. Through similar deals Affymax is likely to try to undercut Epogen’s price; its less frequent dosing schedule should mean lower treatment costs anyway. The company anticipates initial sales to mainly originate from smaller dialysis centres.

A cardiovascular safety signal that emerged in phase III trials of pre-dialysis patients very nearly de-railed the product for Affymax (Affymax reeling from Hematide safety scare, June 21, 2010). These signals have also been seen by the other Epo agents on the market, which include Amgen’s Aranesp and Johnson & Johnson’s Procrit, which are mainly used pre-dialysis.

However Amgen will play heavily on this finding in attempts to protect Epogen, with its long track record of clinical use. Takeda and Affymax have a fight on their hands.

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