CD28 and lung carcinoma: On the other hand, Kamphorst et al. found that, in lung cancer patients, proliferating Ki67+PD-1+CD8+ T cells were increased in peripheral blood, and subsequently activated (CD38+, HLA-DR+) and mostly expressed CD28 (57), implying that CD28 signaling is associated with rescue of the exhausted CD8+ T cells in PD-1 targeted therapies.