The approval of Novartis’s siponimod, now trademarked Mayzent, marks a milestone for the Swiss group. Mayzent, a sphingosine 1-phosphate receptor modulator, is the first approved drug to treat secondary progressive multiple sclerosis (SPMS), giving Novartis a useful niche in MS, where some of the industry’s biggest products will face generic competition in the next few years. Novartis has claimed that up to 80% of patients with relapsing remitting MS, the most common form of the illness, will develop SPMS, which is characterised by worsening symptoms and invalidity. This could explain why Mayzent is forecast to be one of the biggest drugs launched this year but, as companies are increasingly finding, matching premarket expectations is not easy, even with novel products. One thing that could dampen Mayzent sales is the fact it can be difficult to define when a patient has moved from RRMS to SPMS, and patients often continue to take their primary medication when symptoms worsen. Novartis has priced Mayzent at $88,000 a year – it will be interesting to see if this is in line with any recommendation from the US cost-effectiveness watchdog Icer, which is due to deliver a report on the drug’s clinical effectiveness and value on May 2.