CD4 and non-small cell lung carcinoma: In another study of 45 NSCLC patients who received ICIs, 21 patients with an increase in the CD28−CD27−CD4+ T cell subset after 1 cycle of ICIs had no response, and all experienced disease progression.[13] In addition, patients with HPD had a lower number of CD28−CD27−CD4+ T cells in baseline peripheral blood compared to those who progressed on ICIs but did not develop HPD.[13] Taken together, the CD4 subset may be a potential biomarker for identifying patients who are at risk of HPD on ICI treatment.