Transient asymptomatic pulmonary opacities and interstitial lung disease in -mutated non-small cell lung cancer treated with osimertinib.

Introduction: Osimertinib is a third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) approved as first-line therapy for advanced -mutated non-small cell lung cancer (NSCLC). Some osimertinib-related interstitial lung diseases (ILDs) were shown to be transient, called transient asymptomatic pulmonary opacities (TAPO)-clinically benign pulmonary opacities that resolve despite continued osimertinib treatment-and are not associated with the clinical manifestations of typical TKI-associated ILDs.

Methods: In this multicentric study, we retrospectively analyzed 92 patients with -mutated NSCLC treated with osimertinib. Computed tomography (CT) examinations were reviewed by two radiologists and TAPO were classified according to radiologic pattern. We also analyzed associations between TAPO and patients' clinical variables and compared clinical outcomes (time to treatment failure and overall survival) for TAPO-positive and TAPO-negative groups.

Results: TAPO were found in 18/92 patients (19.6%), with a median follow-up of 114 weeks. Median onset time was 16 weeks (range 6-80) and median duration time 14 weeks (range 8-37). The most common radiologic pattern was focal ground-glass opacity (54.5%). We did not find any individual clinical variable significantly associated with the onset of TAPO or significant difference in clinical outcomes between TAPO-positive and TAPO-negative groups.

Conclusions: TAPO are benign pulmonary findings observed in patients treated with osimertinib. TAPO variability in terms of CT features can hinder the differential diagnosis with either osimertinib-related mild ILD or tumor progression. However, because TAPO are asymptomatic, it could be reasonable to continue therapy and verify the resolution of the CT findings at follow-up in selected cases.