Interstitial lung disease/pneumonitis resulting from ALK inhibitors is relatively rare (1.2-8% of patients) (149) (150) (151). In a case study of a Korean ALK-rearranged metastatic lung adenocarcinoma patient, ceritinib induced organizing pneumonia (152). Treatment was ceased and the patient was treated with antibiotics and recovered. In a study testing crizotinib in Japanese patients with ALK-positive non-small cell lung cancer, the incidence of interstitial lung disease was 5.77%, and interstitial lung disease developed within 4 weeks in 41.9% patients from the start of crizotinib treatment and within 8 weeks in 69.2% of patients (153). In a clinical study of 250 NSCLC patients treated with ALK inhibitors, including crizotinib or ceritinib, the median time from the start of treatment to the development of pneumonitis, which occurred in 11 of the patients, was 5 months (range 0.5-11 months) (154).