The phase II DeLLphi-301 trial demonstrated that tarlatamab, a DLL3/CD3 BiTE, achieved comparable response rates (40% vs. 32%) and progression-free survival (4.9 vs. 3.9 months) across SCLC patients irrespective of DLL3 expression thresholds, suggesting the involvement of DLL3-independent immune activation mechanisms (57). The gene discussed is DLL3; the disease is small cell lung carcinoma.