The number of drugs to treat orphan diseases is set to rise, yet in some of these disease areas pipelines are dry and launches scarce

There can be no doubt that the shifting global healthcare landscape has lead to increased interest in treatments for orphan diseases. Complex as they are with particular regulatory, market access and communication needs, drugs to treat orphan diseases will account for approximately one-third of NMEs to 2016, according to IMS. 

The IMS Institute for Health Informatics report, The Global Use of Medicines: Outlook Through 2016, forecasts that global launches for NMEs will rebound to 32 to 37 per year through 2016 – up from fewer than 30 in four of the last seven years. But one orphan disease in particular that is unlikely to feature prominently among NMEs is amyotrophic lateral sclerosis (ALS). The most common type of motor neurone disease (MND), accounting for around 80 per cent of all cases worldwide, it remains underserved with leading business intelligence provider GlobalData stating that the 'therapeutics market [for ALS] is woefully inadequate'.

In 2011, the global ALS market was estimated at $112m, but this value is expected to decline to $70m by 2019. Yet, patient numbers are set to rise, due to a growing elderly population and increasing disease awareness, according to GlobalData's report Amyotrophic Lateral Sclerosis (ALS) – Analysis and Market Forecasts to 2019. Current treatment options are limited to off-label medications that offer symptomatic relief and Rilutek (riluzole; Sanofi), the only approved disease-modifying treatment for ALS, which is due to come off patent later this year. 

The unmet need for ALS treatments with a novel mechanism of action, which can alter disease progression, remains high. There are few late-stage therapies in the pipeline: potential launches to 2019 include, Avicena's ALS-02 (2015) and Mitsubishi Tanabe's Radicut (edaravone) (Japan only, 2013). Although, as GlobalData says, these products will expand the market, it concedes that they 'will not transform the treatment paradigm, as they will be mainly used as add-on treatments to Rilutek'. 

The most promising drug, Biogen's dexpramipexole, was discontinued in January due to a lack of efficacy and improved survival in phase III trial results. According to Adis International the exploration of additional mechanisms of action in preclinical trials, which have proved to have limited applicability in human trials, means that future treatments should focus on pathogenic features seen solely in human ALS.

By Clare Bates, editorial director - PMGroup