TAPO in first-line osimertinib therapy and continuation of osimertinib

Background: Osimertinib is associated with a relatively high frequency of drug-induced interstitial lung disease (D-ILD), and transient asymptomatic pulmonary opacities (TAPO) have been reported to occur during osimertinib administration. The frequency of TAPO during first-line treatment and the pros and cons of osimertinib continuation is unknown. Methods: This was a multicenter, retrospective study. The purpose of this study was to research the frequency of TAPO and to evaluate osimertinib continuation in first-line therapy. We also evaluated progression-free survival (PFS) including subgroup analysis. Results: From August 2018 to December 2020, 133 patients were enrolled into the study. The median observation period was 23.2 months (0.3-48.3 months). Thirty patients (22.6%) experienced D-ILD events, including 16 patients (12.1%) with CTCAE grade 1, five patients (3.8%) with grade 2, and nine patients (6.7%) with grade 3 and above D-ILD. Among the patients with grade 1 D-ILD, 11 cases (8.3%) of TAPO were observed, and all patients succeeded in osimertinib continuation. The TAPO images were characterized by localized patchy opacities (73%). The median PFS was 22.6 months (95% confidence interval [CI]: 17.8-28.7 months). Patients with TAPO had a significantly longer PFS than patients with non-TAPO D-ILD in the multivariate analysis. Conclusions: This study showed that grade 1 D-ILD might include TAPO and that patients with TAPO might have good PFS. We need to consider the possibility of osimertinib continuation when lung opacities appear.