Early-onset interstitial pneumonitis in a patient with advanced non-small cell lung cancer treated with crizotinib and osimertinib.

Both crizotinib and osimertinib have been reported to have an adverse effect of interstitial pneumonitis in the treatment of non-small cell lung cancer (NSCLC). Here, we report the case of a 60-year-old male patient with advanced NSCLC resistant to osimertinib. Crizotinib was administered in combination with osimertinib due to elevated mesenchymal epithelial transition (MET) copy number amplification. However, early-onset interstitial pneumonitis occurred within two days.