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The FDA is expected to decide on Molbreevi for Autoimmune pulmonary alveolar proteinosis by November 22, 2026, under a BLA from Savara.
What the FDA is deciding on Molbreevi for Pulmonary Alveolar Proteinosis
The FDA is reviewing Savara's application to approve Molbreevi (molgramostim) for autoimmune pulmonary alveolar proteinosis.
Inhaled GM-CSF breathed in once a day through a nebulizer. The FDA extended its review by 3 months, from August 22 to November 22, 2026, after classifying Savara's answers to information requests as a major amendment, and Savara said the agency cited no safety, efficacy or manufacturing concerns. If approved it would be the first FDA-approved drug for autoimmune PAP.
Who the Molbreevi decision matters to
Pulmonary alveolar proteinosis (PAP) is a rare lung disease in which a soapy substance called surfactant builds up inside the air sacs because the cells meant to clear it have stopped working. In the autoimmune form, which accounts for about 9 in 10 cases, the body makes antibodies against GM-CSF, the signal those cells need.
The only standard treatment is washing the lungs out under anesthesia. An inhaled replacement for GM-CSF, molgramostim, has an FDA decision due November 22, 2026 and would be the first FDA-approved drug.
Prevalence: Autoimmune PAP affects about 6 to 7 people per million (NORD and the PAP Foundation) and makes up 85-90% of cases, with hereditary, secondary and congenital forms each around 5%. See our full Pulmonary Alveolar Proteinosis page for current treatments, recruiting trials, and community resources.
How Molbreevi works
Molbreevi: inhaled recombinant human GM-CSF that restores the signal alveolar macrophages need to clear surfactant from the lungs. Our full Molbreevi profile covers how it works, side effects in plain language, and its trial history.
What an approval or a rejection of Molbreevi would mean
An approval starts a second race rather than ending the first one: specialty pharmacy setup, insurance review, and patient assistance typically take weeks even when everything goes right. Our guide to the 90 days after a rare disease approval explains the timeline and the moves families can make on day 1.
A complete response letter would mean the FDA declined to approve in the application's current form. The letter describes what the FDA wants addressed, and the company then decides whether to resubmit, run more studies or stop. Either way, this page updates with the outcome and what it means.
Where Pulmonary Alveolar Proteinosis treatment stands today
Read our full Pulmonary Alveolar Proteinosis treatment summary
There is no FDA-approved drug for PAP in the United States as of October 2026, so every medicine used for it is given off label or inside a trial. That may change on November 22, 2026, the FDA's target date for molgramostim inhalation solution, which Savara plans to sell under the name Molbreevi.
Molgramostim is a manufactured form of GM-CSF that patients breathe in through a nebulizer once a day, replacing the signal the autoantibody has blocked. In the Phase 3 IMPALA-2 trial, published in the New England Journal of Medicine in 2025, 164 people with autoimmune PAP were randomized to 300 micrograms of molgramostim or placebo for 48 weeks.
The main measure was DLCO, a breathing test of how well oxygen crosses from the lungs into the blood.
At week 24 it improved by 9.8 percentage points on molgramostim versus 3.8 on placebo, and the gap widened by week 48 (11.6 versus 4.7). Side effects were similar between the 2 groups.
The FDA extended its review by 3 months; the company has said decisions from European and UK regulators are expected in the first quarter of 2027 and the fourth quarter of 2026.
The IMPALA trials enrolled only people with autoimmune PAP confirmed by the GM-CSF autoantibody test, so getting that blood test is the first practical step. NORD lists rituximab and plasma exchange as experimental options for the autoimmune form, and the PAP Foundation describes macrophage transplantation and gene therapy as approaches in development for the hereditary form.
A pulmonologist at one of the PAP Foundation's listed clinical centers is the best person to ask about enrolling, and the PAP Alliance runs a Find a Doctor service and webinars.
The Pulmonary Alveolar Proteinosis page has every treatment and trial →Meanwhile, 6 Pulmonary Alveolar Proteinosis studies are open or about to open
Whatever the FDA decides here, research on Pulmonary Alveolar Proteinosis does not stop. Of these, 4 test a treatment; the others follow patients over time. The most recently updated:
We'll email you when the decision is public, with what it means in plain language, and when new trials open for Pulmonary Alveolar Proteinosis. Unsubscribe anytime.
- Trial Alerts, when a new trial opens or a trial changes
- Disease Updates, FDA decisions and condition news, usually 1 or 2 emails a month
Frequently asked questions
When will the FDA decide on Molbreevi?
The FDA's target date (PDUFA date) for Molbreevi in Autoimmune pulmonary alveolar proteinosis is November 22, 2026.
Who disclosed it: Savara. The FDA does not publish these dates.
Can it move: the FDA can act early, and a major amendment to the application can push the date back 3 months.
Source: Savara press release
What is Molbreevi being reviewed for?
Savara submitted a BLA for Molbreevi in Autoimmune pulmonary alveolar proteinosis.
What to know: Inhaled GM-CSF breathed in once a day through a nebulizer. The FDA extended its review by 3 months, from August 22 to November 22, 2026, after classifying Savara's answers to information requests as a major amendment, and Savara said the agency cited no safety, efficacy or manufacturing concerns. If approved it would be the first FDA-approved drug for autoimmune PAP.
How it works: Inhaled recombinant human GM-CSF that restores the signal alveolar macrophages need to clear surfactant from the lungs.
More: the Molbreevi drug page explains it in plain language.
Is there already an FDA-approved treatment for Pulmonary Alveolar Proteinosis?
No. No medicine's current FDA label names Pulmonary Alveolar Proteinosis, checked October 21, 2026.
Check: the Pulmonary Alveolar Proteinosis page also searches FDA drug labels for approved treatments.
What did the Molbreevi trials show?
IMPALA-2 (NCT04544293) was a Phase 3, double-blind, placebo-controlled trial at 43 sites in 16 countries that randomized 164 adults with autoimmune PAP to inhaled molgramostim 300 micrograms or placebo once daily for 48 weeks; 81 received molgramostim and 83 placebo, with Japan, the United States, Turkey, South Korea and Germany the largest enrolling countries. The primary endpoint was the change at week 24 in DLCO, a breathing test of how well gas crosses from the lungs into the blood.
More: the Molbreevi drug page has the full trial history and sources.
What are the side effects of Molbreevi?
In the 48-week placebo-controlled part of IMPALA-2, the share of patients with at least 1 adverse event and with at least 1 serious adverse event was similar in the molgramostim and placebo groups, and no deaths occurred. Savara's patient summary lists cough and fever as the most common adverse events in people taking molgramostim.
More: the Molbreevi drug page has the safety details reported so far.
Can I get Molbreevi before the FDA decides?
Usually only through a clinical trial or an expanded access program, and the company decides whether to offer one.
Trials: 6 Pulmonary Alveolar Proteinosis studies are open or about to open, 4 of them testing a treatment. See them.
Check your fit: Match Me compares your details with every open trial.
Expanded access: your doctor can ask Savara directly. Registered programs are listed on ClinicalTrials.gov.
How much will Molbreevi cost?
Savara has not announced a price. Drugmakers usually set it around approval.
Help paying: drugmaker programs and charity funds usually open at launch.
Find help: the patient assistance finder lists programs by insurance type.
What happens after the Molbreevi decision?
This page updates with the outcome the day it is announced.
If approved: getting the drug still takes time. Specialty pharmacy setup, insurance review and patient assistance often take weeks. Our guide covers what families can do on day 1.
If not approved: a complete response letter means the FDA declined the application in its current form. Many are about manufacturing or how data were presented, and companies often resubmit.
Where this date comes from
The FDA does not publish PDUFA dates; companies disclose them. This one comes from Savara press release. Dates can move, and the FDA can act early or late. This page rechecks against our calendar, which is re-verified daily.