CD4 and small cell lung carcinoma: Although their study did not further investigate the infiltration of T cell subpopulations or other immune cells, based on the negative prognostic role of YAP1 in ES-SCLC patients receiving ECT treatment, we infer that Tregs are the main component of CD4-positive cells in the tissues of patients with high YAP1 expression, and the poor efficacy of chemo-immunotherapy may be related to increased infiltration of Tregs.