PDCD1 and small cell lung carcinoma: The failure of the KEYNOTE‐604 and ECOG‐ACRIN EA5161 studies left us wondering whether PD‐1 monoclonal antibodies in combination with chemotherapy for ES‐SCLC could provide benefit, but the ASTRUM‐005 study has shown us again that similar study designs, drug mechanisms of action, and results may be different.