TP53 and small cell lung carcinoma: Moreover, a significant association was found between high tumor mutation burden (TMB) and mutations involved in TP53, CREBBP, EPHA3, KMT2D, ALK and RB1. Approximately 33.33% of patients with SCLC harbored at least one actionable alteration annotated by OncoKB, of which one patient had alterations of level 1; seventeen patients had level 3; fifteen patients possessed level 4.