The drug efficacy and safety arm of the European Medicines Agency has recommended Orexigen Therapeutics’ new anti-obesity drug Mysimba for certain patients to help them lose weight.
The drug is a combination of the antidepressant bupropion and Orexigen’s formulation of naltrexone, a drug designed to prevent drug dependence.
The CHMP has recommended a marketing authorisation for Mysimba (naltrexone/bupropion) for weight management of overweight or obese adults. The medicine is recommended for use in addition to a reduced-calorie diet and physical activity.
This comes just several months after Mysimba gained US approval, where it is known under the brand name Contrave, and is co-marketed with Japanese firm Takeda.
Despite the size of the market sales of the drug are not estimated to reach blockbuster status, with analysts’ predicting it will make just $200m by 2016.
The pill had a difficult road to market as it contains an antidepressant and in the US needs to carry a warning about increased risk of suicidal thoughts (known as suicide ideation) and other behaviours, as well as concerns over its heart safety.
Although obesity is a major health concern in Europe and across all Western markets, all new anti-obesity drugs since the approval of Roche’s Xenical in 1999 have so far failed to create a market or give their manufacturers a major revenue boost.
This is predominately due to drug safety concerns – especially for cardiovascular safety – with weight loss from most marketed treatments modest but with high side effect ratios (Xenical’s long list of side effects include the risk of ‘bullous eruptions’, urinary tract infections and hepatitis).
There are now four prescription medicines for obesity in the US, including Vivus’ Qsymia (phentermine/topiramate) and Arena Pharmaceuticals’ Belviq (lorcaserin), which were both approved in the last two years, alongside Xenical and Mysimba.
Arena had been seeking a European licence but last year pulled its marketing application for Belviq because of the Agency’s concerns over its safety profile and the risk of patients developing tumours, alongside a modest benefit.
In 2012 the EMA turned down Vivus’ Qsymia, again due to a negative side effect profile, specifically around its long-term effects on the heart and psychiatric effects, such as an increased risk of depression.
Xenical remains the highest earner of the four globally and brings in around $500 million a year – Qsymia and Belviq have as yet failed to break the $100 million marker.
Altering the ‘reward pathways’
Mysimba works as a prolonged release tablet that has an effect on two key areas of the brain responsible for the control of food intake and energy expenditure, and for the reward pathways associated with eating food.
The effectiveness of Mysimba was assessed in four pivotal studies that included obese and overweight patients with and without weight-related conditions treated for one year.
All patients enrolled in trials were required to change their lifestyle to incorporate a reduced-calorie diet and regular physical activity. Across these studies, more patients treated with Mysimba achieved clinically-relevant weight loss than patients treated with placebo.
But the CHMP has put limitations on its recommendation, and says that patients who start treatment with Mysimba should be evaluated after 16 weeks.
If a patient has not lost at least five per cent of their initial body weight by this time, treatment with Mysimba should be stopped, the CHMP said.
The final decision as to whether this drug will be made available throughout the European Union will be made by the European Commission – a decision that typically takes around three months.