FDA assigns goal date for Molbreevi for rare lung disease

The FDA has granted priority review for Molbreevi (molgramostim) to treat patients with autoimmune pulmonary alveolar proteinosis, a rare respiratory disease. Autoimmune pulmonary alveolar proteinosis affects approximately 7 in 1 million people in the United States, according to the American Lung Association. It is caused by a buildup of proteins and fats in the alveoli, or air sacs, of the lungs, which prevents air from getting through the alveoli.

Patients with aPAP experience shortness of breath, cough and secondary lung infections. In severe cases, a lung transplant may be required. The only option to clear excess fluid from the lungs is by performing a lung lavage, in which the lung is flushed with saline.

Developed by Savara, Molbreevi is a recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF) that is administered using the eFlow nebulizer from PARI Pharma. Molbreevi is believed to activate macrophages in the lung alveoli, potentially restoring their ability to clear the buildup of proteins and fats. The FDA has assigned a goal date of Aug. 22, 2026.

If approved, Molbreevi would be the first FDA-approved treatment for patients with autoimmune pulmonary alveolar proteinosis. Savara has chosen PantheRx Rare Pharmacy as its specialty pharmacy partner. Savara officials said in a recent investor presentation that they expect Molbreevi will be priced between $400,000 and $500,000 per year and that 60% of patients will likely be covered by commercial insurance.

The biologic license application is based on data from the phase 3 IMPALA-2 trial, which was published in the New England Journal of Medicine in August 2025. In this trial, 164 patients with autoimmune pulmonary alveolar proteinosis were randomized to receive either Molbreevi or placebo for 24 weeks and 48 weeks. The primary endpoint was the change from baseline to week 24 in the diffusing capacity of the lungs for carbon monoxide. This is a test that measures the amount of carbon monoxide that is transferred per minute to red blood cells, which provides an estimate of the oxygen diffusion.

Once-daily inhaled Molbreevi led to a greater increase in pulmonary gas transfer than placebo in patients with autoimmune pulmonary alveolar proteinosis.

Most adverse events were mild or moderate in severity; adverse events led to discontinuation of two patients in the Molbreevi group and one patient in the placebo group. A serious adverse event occurred in 14 patients receiving Molbreevi and 20 receiving placebo. The most common adverse events were Covid-19, cough, pyrexia, nasopharyngitis, arthralgia, headache, and diarrhea. Covid-19 and diarrhea occurred in a higher percentage of patients in the Molbreevi group than in the placebo group.

“We believe the considerable body of data in the application demonstrates Molbreevi improves pulmonary gas transfer, quality of life, and the clinical symptoms associated with this rare and debilitating lung disease,” Matt Pauls, chair and CEO of Savara, said in a news release.

Company officials said they plan to also submit marketing authorization applications for Molbreevi to the European Medicines Agency (EMA) and the Medicines and Healthcare Products Regulatory Agency (MHRA) by the end of the first quarter of 2026.