Background: We conducted a phase III investigator-initiated clinical trial (PAGE: NCT02835742) of GM-CSF inhalation therapy for 24 weeks in 64 patients with autoimmune pulmonary alveolar proteinosis (aPAP), and reported its efficacy and safety (Tazawa et al., N Engl JMed, 2019;381:923).
Objective: To know the duration of treatment effect, the presence or absence of late-onset side effects, and predictors of poor prognosisafter PAGE trial.
Methods: A survey was started immediately after the end of the trial, and the prognosis was prospectively followed for 2 years. EDC was applied for data collection, data management, monitoring and statistical analysis. This study was conducted in compliance with the Declaration of Helsinki.
Results: Of the 64 PAGE participants, 61 gave informed consent and were followed up for 2 years. To summarize the results, (1) the oxygenation-improving effect of GM-CSF inhalation therapy was transient, i.e., the improvement in arterial oxygen partial pressure in the GM-CSF group was greater than that in the placebo group until one year later. (2) The period without additional treatment was affected by whether %VC at the time of enrollment was greater or less than 80%. (3) No late side effects were observed.
Discussion: A previous report also cited %VC more than 80% as a prognostic threshold (Tazawa et al., Chest, 2014), which was also confirmed in this study. As a guideline for therapeutic intervention, it is important to manage the %VC so that it does not fall below 80%.