FDA Clears Sirolimus (Rapamune) for Rare Lung Disease

Megan Brooks

May 29, 2015

The US Food and Drug Administration (FDA) has approved the mTOR pathway inhibitor sirolimus (Rapamune, Pfizer), the first drug to treat lymphangioleiomyomatosis (LAM), a very rare, progressive lung disease that primarily affects women of childbearing age.

LAM is estimated to affect between two and five women per million women worldwide, the FDA notes in a news release.

The disease is characterized by abnormal proliferation of smooth muscle cells throughout the lungs, in the bronchioles, alveolar septa, perivascular spaces, and lymphatics, leading to destruction of the lung and airflow obstruction.

The safety and efficacy of sirolimus for treatment of LAM were demonstrated in a placebo-controlled clinical trial of 89 patients for a 12-month treatment period, followed by a 12-month observation period.

The primary endpoint was the difference between the groups in the rate of change in forced expiratory volume in one second (FEV1). The difference in the average decrease in FEV1 during the 12-month treatment period was approximately 153 mL. After discontinuation of sirolimus, the decline in lung function resumed at a rate similar to that of the placebo group.

The most commonly reported side effects associated with sirolimus for treatment of LAM are mouth and lip ulcers, diarrhea, abdominal pain, nausea, sore throat, acne, chest pain, leg swelling, upper respiratory tract infection, headache, dizziness, muscle pain, and elevated cholesterol. Serious side effects including hypersensitivity and edema have been observed in renal transplant patients.

Sirolimus was originally approved in 1999 as an immunosuppressive agent to help prevent organ rejection in kidney transplant patients. The drug received breakthrough therapy designation and priority review for LAM after it was shown to offer substantial improvement over available therapies, the FDA says.

Development of this drug was also supported in part by the FDA Orphan Products Grants Program, which provides grants for clinical studies on safety and/or effectiveness of products for use in rare diseases or conditions.

"Different FDA programs, such as orphan product designation and breakthrough therapy designation, provide sponsors with financial incentives and access to increased interactions and advice from FDA to facilitate development and timely approval of innovative treatments for rare diseases, which might not otherwise be developed," John Jenkins, MD, director of the Office of New Drugs in the FDA's Center for Drug Evaluation and Research, notes in the release. "These kinds of special programs make it possible for FDA to help drug manufacturers get life-saving drugs to the people who need them much more quickly."


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