Treatment of Pulmonary Alveolar Proteinosis in Confirmed Autoimmune aPAP with Raised GM-CSF Autoantibody Titres
Clinical Scenario
This protocol applies to patients with confirmed autoimmune pulmonary alveolar proteinosis (aPAP) identified by raised GM-CSF autoantibody titres, who present with active or worsening disease. GM-CSF autoantibody measurement is objective and reproducible, with established laboratory thresholds for diagnosis. Treatment is indicated when disease is active or progressive.
Treatment Approach (Overview)
The protocol for this scenario includes a lavage-based procedure and/or an inhaled GM-CSF therapy — chosen according to disease severity and the presence of gas exchange impairment.
Specific agents, sequencing, decision criteria, and full evidence summary are in the complete protocol.
Treatment Goals
- Symptomatic improvement and improved walking distance
- Reduced alveolar–arterial oxygen difference (PA–aO₂)
- Improved arterial oxygen tension (PaO₂) at 6 months
- Improved diffusing capacity (DLCO) at 6 months
References
DOI: 10.1183/20734735.0224-2024
- GM-CSF antibody measurement is objective, reproducible and has high accuracy for diagnosing aPAP with a level of 10.2 µg·mL−1 or above the threshold of the individual laboratory references.
- Treatment is indicated in patients with active or worsening disease.
- We recommend performing bilateral WLL in patients with aPAP with evidence of gas exchange impairment and either symptoms or functional impairment (strong recommendation, very low certainty of evidence).
- We recommend inhaled GM-CSF for symptomatic patients with confirmed aPAP (strong recommendation for the intervention; very low certainty of evidence).
- There was no significant improvement in FVC at short or long term follow up after WLL, but a significant symptomatic improvement was reported.
- Furthermore, improvements in walking distance, a suggestion of improvement of PaO2 and a trend toward improvement on PA–aO2 were also seen following WLL.
- Pooled results from these trials showed that intermittent inhaled GM-CSF reduced PA–aO2 (mean difference (MD) −4.36 mmHg, 95% CI −7.71; 1.01), improved PaO2 (MD 4.47 mmHg, 95% CI 1.16; 7.78) and improved DLCO (MD absolute change of 4.05%, 95% CI 0.23; 7.88) at 6 months compared to placebo.
View source ↗