Abstract Introduction/Rationale AP01 is a novel formulation of pirfenidone, an FDA approved, orally administered drug optimized for inhalation using the Pari eFlow nebulizer. Its safety, tolerability and efficacy is being evaluated in clinical trials for progressive pulmonary fibrosis (PPF) and idiopathic pulmonary fibrosis (IPF). The AP01-002 (ATLAS) study of AP01 in IPF began in June 2019 and was followed by the AP01-005 open label extension (OLE) study. Additional treatment naïve study participants with IPF and PPF were enrolled in the OLE study. We report AP01 safety and efficacy in patients with up to 240 weeks follow up. Methods The ATLAS study randomized IPF patients to 50 mg AP01 once daily (QD) or 100 mg AP01 twice daily (BID) for 24 weeks. The Data and Safety Monitoring Board advised that all 50 mg QD subjects were to be transitioned to 100 mg BID at 24 weeks. All cohorts in the OLE study received 100 mg BID AP01 throughout. Forced Vital Capacity (FVC) was recorded every 3 months. We report the change in FVC from baseline of the original study to latest visit, the annualized decline in FVC, and the percentage of participants experiencing any adverse events (AEs). These data were compared with published pooled data from the 3 pivotal clinical trials of oral pirfenidone. Results 41/91 ATLAS subjects rolled over into the OLE study, and an additional 31 with IPF and 28 with PPF were added. 17 ATLAS subjects remained on AP01 at 240 weeks. 10/31 naïve IPF subjects and 15/28 naïve PPF subjects had reached week 144 on AP01. AEs were present in 95.3% of participants overall, demonstrating similar frequencies across cohorts. No new safety signals were demonstrated and some AEs such as cough, nausea or rash were not reported during weeks 144 to 240 The annual change in FVC was -30 ml/year in the OLE study. Roll-over patients from ATLAS study had an FVC change of -69ml/year; naïve IPF patients had a FVC change of -120ml/year while naïve PPF patients had a FVC change of +11ml/year (Table 1). Conclusions Over up to 240 weeks follow up, AP01 appears to have continuing efficacy with a stable safety profile over the long-term of open-label treatment. This data provides support for the ongoing evaluation of AP01 in Phase 2 and 3 studies.