In a separate classification effort, transformed SCLCs (T-SCLCs) have been categorized into a “LUAD-feature retained” subgroup with high NKX2–1 expression and a “LUAD-feature absent” subgroup harboring canonical SCLC genomic features like TP53/RB1 co-inactivation. The gene discussed is NKX2-1; the disease is small cell lung carcinoma.