CD28 and Patent ductus arteriosus: Since Anti‐PD‐1/PD‐L1 treatment is targeting the exhausted CD8+ T cells and turn the exhausted CD8+ T cells into active state, which is dependent on CD28 45, 46, injection to patients with anti‐PD‐1/PD‐L1 antibodies is presumed to make the status of PD‐L1‐positive cancerous mass to the PD‐L1‐negative one, resulting in that infiltrating CD8 T cells would attack HLA‐class I‐positive PDA and improve patient prognosis.