ORLANDO, Fla., May 19, 2026
Savara presented new long-term efficacy and safety data from the ongoing IMPALA-2 Phase 3 clinical trial evaluating molgramostim inhalation solution for patients with autoimmune pulmonary alveolar proteinosis (aPAP) at the American Thoracic Society (ATS) International Conference 2026. The updated open-label (OL) extension results showed that patients receiving molgramostim continued to experience sustained improvements in lung function and respiratory quality of life over extended treatment periods, while patients previously treated with placebo demonstrated significant gains after switching to active therapy.
The IMPALA-2 study is currently the largest and longest clinical trial ever conducted in aPAP, enrolling 164 patients globally. During the initial double-blind phase, participants received either molgramostim 300 µg or placebo once daily through nebulization. Following completion of the blinded portion, all eligible participants entered the ongoing 96-week open-label extension, where every patient receives molgramostim treatment. Importantly, 100% of patients who completed the double-blind period chose to continue into the open-label phase, reflecting strong patient confidence and tolerability.
Long-Term Molgramostim Treatment Shows Sustained Lung Function Improvement
Data from the first 48 weeks of the open-label treatment period demonstrated continued improvement in pulmonary gas transfer among patients who received molgramostim throughout both study phases. Researchers measured efficacy primarily through changes in DLco% (diffusing capacity of the lungs for carbon monoxide), a critical indicator of lung function and oxygen exchange capability in aPAP patients.
Patients treated continuously with molgramostim during both the double-blind and open-label phases achieved an overall 14.7% mean improvement in DLco% from baseline through Week 96. Meanwhile, patients initially assigned to placebo who later crossed over to molgramostim showed substantial improvement after beginning active treatment, with an 8.8% increase in DLco% during Weeks 48–96 alone. These findings suggest that longer-term exposure to molgramostim may provide durable respiratory benefits while also offering meaningful recovery potential for patients who initiate therapy later.
Researchers also reported strong improvements in respiratory health-related quality of life (HRQoL) using the St. George’s Respiratory Questionnaire Total (SGRQ-T) and Activity (SGRQ-A) scores. Patients receiving continuous molgramostim treatment achieved sustained reductions in symptom burden, fatigue, and respiratory limitations over the extended treatment period. Patients who crossed over from placebo similarly experienced notable quality-of-life improvements once molgramostim therapy began.
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High Patient Retention and Favorable Safety Profile Strengthen Clinical Outlook
The trial demonstrated exceptionally strong patient retention rates, further reinforcing the therapy’s long-term tolerability profile. Of the 164 patients enrolled, 160 completed the double-blind phase, and every one of those patients entered the open-label extension. At the latest data cutoff, only 9 patients discontinued treatment, resulting in a 94% retention rate over the course of the ongoing study.
Importantly, molgramostim continued to show a favorable safety and tolerability profile consistent with previously reported findings from earlier phases of the IMPALA program. Researchers stated that no study discontinuations were linked to treatment-related adverse events, and no new safety concerns were identified during the open-label extension period.
According to lead investigator Bruce Trapnell, M.D., the results provide additional evidence supporting the long-term therapeutic potential of molgramostim in aPAP. He emphasized that both continuous-treatment patients and placebo crossover patients demonstrated clinically meaningful improvements across lung function and respiratory quality-of-life measures, reinforcing the durability of treatment benefit.
Savara Advances Potential First Pharmacologic Therapy for aPAP
Autoimmune pulmonary alveolar proteinosis is a rare and progressive respiratory disease caused by impaired clearance of surfactant within the lungs due to dysfunction of alveolar macrophages. Over time, surfactant accumulation interferes with oxygen exchange, leading to worsening shortness of breath, chronic fatigue, reduced exercise capacity, and potentially severe complications including lung fibrosis and respiratory failure.
Molgramostim is a recombinant human GM-CSF therapy designed to restore macrophage function and improve surfactant clearance in patients with aPAP. The inhaled therapy is administered using the proprietary eFlow® Nebulizer System, specifically optimized for pulmonary drug delivery.
The new IMPALA-2 data further strengthen Savara’s position as it advances molgramostim toward potential regulatory approval as one of the first targeted pharmacologic treatments for autoimmune pulmonary alveolar proteinosis.
Source: Savara, press release
