CD274 and small cell lung carcinoma: The immune microenvironment of SCLC tumors is generally acidic, enriched with glutathione and hydrogen peroxide,[36] in addition to sharing key pathophysiological features common to solid tumors such as hypoxia.[37] Moreover, SCLC exhibits low levels of tumor‐infiltrating lymphocytes,[38] significantly reduced expression of programmed PD‐L1,[39, 40] deficient expression of major histocompatibility complex class I (MHC‐I) molecules,[41] and absent expression of MHC class II proteins,[42] all of which contribute to its classification as a cold TIME.