On Feb. 24, 2014, the U.S. Food and Drug Administration approved Myalept (metreleptin for injection) as replacement therapy to treat the complications of leptin deficiency, in addition to diet, in patients with congenital generalized or acquired generalized lipodystrophy.
Generalized lipodystrophy is a condition associated with a lack of fat tissue. Patients with congenital generalized lipodystrophy are born with little or no fat tissue. Patients with acquired generalized lipodystrophy generally lose fat tissue over time. Because the hormone leptin is made by fat tissue, patients with generalized lipodystrophy have very low leptin levels. Leptin regulates food intake and other hormones, such as insulin.
Patients with both types of generalized lipodystrophy often develop severe insulin resistance at a young age and may have diabetes mellitus that is difficult to control or very high levels of triglycerides in the blood (hypertriglyceridemia) that can lead to inflammation of the pancreas.
"Myalept is the first approved therapy indicated for treating the complications associated with congenital or acquired generalized lipodystrophy and provides a needed treatment option for patients with this orphan disease," said Mary Parks, M.D., deputy director of the Office of Drug Evaluation II in the FDA's Center for Drug Evaluation and Research.
The safety and effectiveness of Myalept, an analog of leptin made through recombinant DNA technology, were evaluated in an open-label, single-arm study that included 48 patients with congenital or acquired generalized lipodystrophy who also had diabetes mellitus, hypertriglyceridemia, and/or elevated levels of fasting insulin. The trial showed reductions in HbA1c (a measure of blood sugar control), fasting glucose, and triglycerides.
Anti-drug antibodies with neutralizing activity to leptin and/or Myalept may develop, which could result in severe infections or loss of treatment effectiveness. T-cell lymphoma has been reported in patients with acquired generalized lipodystrophy, both treated and not treated with Myalept, so healthcare professionals should carefully consider the benefits and risks of treatment with Myalept in patients with significant hematologic abnormalities and/or acquired generalized lipodystrophy. Myalept is contraindicated in patients with general obesity. Myalept is not approved for use in patients with HIV-related lipodystrophy or in patients with metabolic disease, including diabetes mellitus and hypertriglyceridemia, without concurrent evidence of generalized lipodystrophy.
Because of the risks associated with the development of neutralizing antibodies and lymphoma, Myalept is available only through the Myalept Risk Evaluation and Mitigation Strategy (REMS) Program. Under this REMS program, prescribers must be certified with the program by enrolling in and completing training. Pharmacies must be certified with the program and only dispense Myalept after receipt of the Myalept REMS Prescription Authorization Form for each new prescription.
Myalept is also approved with a Medication Guide and instructions for use that provides patients with important information about the medication. The guide will be distributed each time a patient fills a prescription.
The FDA is requiring seven studies (post-marketing requirements) for Myalept, including a long-term prospective observational study (product exposure registry) of patients treated with Myalept, a study to assess for the immunogenicity (antibody formation) of Myalept, and an assessment and analysis of spontaneous reports of potential serious risks related to the use of Myalept. Eight additional studies are being requested as post-marketing commitments.
In clinical trials, the most common side effects observed in patients treated with Myalept were low blood sugar (hypoglycemia), headache, decreased weight, and abdominal pain.
Myalept is marketed by San Diego-based Amylin Pharmaceuticals, L.L.C.