Purpose: Immune checkpoint inhibitor-associated interstitial lung disease (ICI-ILD) is a serious immune-related adverse event. We aimed to evaluate the impact of ICI-ILD severity and imaging patterns or post-ILD cancer therapy on prognosis in patients with non-small-cell lung cancer (NSCLC).
Methods: We retrospectively analysed NSCLC patients who developed ICI-ILD in our institution between January 2016 and March 2019. The primary objective was to report prognosis following onset of ICI-ILD, stratified by severity grade or imaging pattern. The secondary objective was the analysis of cancer therapy after ICI-ILD.
Results: Among 222 patients treated with ICI, 27 (12.2%) developed ICI-ILD. No trend for different prognosis depending on severity grade was seen unless ICI-ILD was fatal. Most patients (91.3%) with organising pneumonia (OP) or nonspecific interstitial pneumonia pattern on imaging showed grade 1 or 2, while all patients with a diffuse alveolar damage (DAD) pattern showed grade 3 or higher, and one reached grade 5. Among patients who overcame ICI-ILD, eight patients (30.8%) have been followed up without chemotherapy because of long-term disease control and seven had shown an OP pattern on imaging at onset of ICI-ILD. Three patients underwent ICI rechallenge, but two showed ICI-ILD recurrence and no patient achieved response to rechallenge treatment.
Conclusion: The DAD pattern may predict short-term adverse prognosis for ICI-ILD. Once ICI-ILD is overcome, severity grade is not associated with prognosis. Even if initial immunotherapy proves effective, ICI rechallenge requires careful consideration.
Keywords: Immune checkpoint inhibitors; Immune-related adverse event; Interstitial lung disease; Non-small-cell lung cancer; Pneumonitis; Prognosis.