CD28 and cancer: Recent data have demonstrated that the CD28‐mediated expression of CD80 or CD86 on cancer cells can increase the cytotoxicity of blinatumomab, a bispecific T‐cell engager targeting CD19 and CD3 to treat Philadelphia chromosome‐negative B‐cell acute lymphoblastic leukemia, as does cotreatment with a monoclonal CD28 antibody.285