An ongoing phase 1b (DeLLphi-303) study (NCT05361395) aims to investigate the safety and efficacy of quadruplet therapy with tarlatamab in combination with CE and a PD-L1 inhibitor (atezolizumab or durvalumab), followed by maintenance treatment with tarlatamab and a PD-L1 inhibitor in patients with ES-SCLC in the first-line setting. Here, CD274 is linked to small cell lung carcinoma.