Clinical significance of interstitial lung abnormalities and immune checkpoint inhibitor‐induced interstitial lung disease in patients with non‐small cell lung cancer

BACKGROUND: Interstitial lung abnormalities (ILAs) are known to be a risk of drug‐induced pneumonitis. However, there are few reports on the relationship between ILAs and immune checkpoint inhibitor‐related interstitial lung disease (ICI‐ILD). We retrospectively investigated the clinical significance of ILAs in patients with non‐small cell lung cancer (NSCLC) receiving ICIs. METHODS: We defined ILAs as nondependent abnormalities affecting more than 5% of any lung zone, including ground‐glass or diffuse centrilobular nodularities, traction bronchiectasis, honeycombing, and nonemphysematous cysts. Early‐onset ICI‐ILD was defined as developing within 3 months after the initiation of ICI administration. RESULTS: Of 264 patients with advanced NSCLC, 57 patients (21.6%) had ILAs (43 fibrotic and 14 nonfibrotic ILAs). The difference between the incidence of ICI‐ILD in patients with or without ILAs was not significant. Of 193 patients treated by ICI monotherapy, 18 (9.3%) developed early‐onset ICI‐ILD. Among patients receiving ICI monotherapy, the incidence of early‐onset ICI‐ILD was significantly higher in patients with than in patients without nonfibrotic ILAs. CONCLUSION: The presence of nonfibrotic ILAs is a significant risk for early‐onset ICI‐ILD in patients with NSCLC undergoing ICI monotherapy. Clinicians should be aware of ILAs, especially nonfibrotic ILAs, before administering ICIs to lung cancer patients.