Current LS-SCLC protocols combining etoposide-cisplatin chemoradiation with prophylactic cranial irradiation achieve transient responses, whereas ES-SCLC first-line treatment incorporates PD-1/PD-L1 inhibitors alongside platinum-based chemotherapy, per IMpower133 and CASPIAN trial frameworks (8–10). The gene discussed is PDCD1; the disease is small cell lung carcinoma.