TP53 and small cell lung carcinoma: In our analysis of the mutational landscape in ES-SCLC patients in CASPIAN (n = 290), we found that the two most common mutations identified were of TP53 in 268 (92.4%) and RB1 in 222 (76.6%) patients, with all other gene mutations identified being seen in < 20% of patients (Fig. 2A).