AstraZeneca’s Myalept has become the first approved treatment for the rare disease lipodystrophy after getting a green light from the FDA.
Myalept (metreleptin) – a recombinant form of the hormone leptin that was unsuccessfully studied as an obesity therapy by Bristol-Myers Squibb (BMS) – has been approved as a replacement therapy for patients with congenital or acquired generalised lipodystrophy.
The US regulator stopped short of giving the nod for Myalept as a treatment for partial lipodystrophy, however, dramatically reducing the number of patients eligible for treatment with the drug. The narrower indication was expected after an FDA advisory panel concluded that AZ’s submitted data was not strong enough to support use in a more heterogeneous population.
The lipodystrophies are a collection of metabolic disorders characterised by loss of fat tissue in parts of the body, such as the skin, and accumulation in others, such as the blood and organs, which results in turn from breakdown in the body’s ability to control energy use. In some cases, this can lead to life-threatening complications such as diabetes, heart and liver disease.
Myalept will be “a much-needed treatment option for patients with this orphan disease”, said Mary Parks, deputy director of the FDA’s Office of Drug Evaluation II.
Lipodystrophies only affect a few thousand people worldwide, which to date have had to be managed using a strict dietary regimen and diabetes drugs to tackle complications. Taking partial lipodystrophy out of the equation means Myalept is likely to be a very small product for AZ, with sales well below the $250m or so a year that might have been forthcoming with a broader label.
AZ has not given up on expanding the label for Myalept in future, however, and said after the FDA panel met in December that it would work with the FDA to try to establish a path for approval in this setting.
The company stressed that metreleptin is not approved to treat the complications of lipodystrophy, such as liver disease, or for lipodystrophies which are caused by HIV infection. The label for the drug also warns of the risk of developing leptin-neutralising antibodies and lymphoma with treatment.
As a result Myalept will also only be available via a risk evaluation and mitigation strategy (REMS) programme, with controls on prescribing and dispensing, and AZ has committed to a series of post-marketing trials to keep tabs on its safety.
AZ is in the process of transferring full rights to Myalept from BMS under the terms of its $4.3bn buyout of their diabetes and metabolic disorders alliance, which completed this year, and says it will launch the injectable drug as soon as possible. BMS acquired rights to metreleptin when it bought Amylin in 2012.
