With the promise of a potentially single-dose curative regimen, CAR-T cell therapies have brought a paradigm shift in the treatment and management of hematological malignancies with 6 approved products in the USA. However, there are no approved CAR-T cell therapies for solid tumors. Herein, we report the clinical pharmacology profile of AMG 119, the first CAR-T cell therapy targeting delta-like ligand 3 (DLL3), in patients with relapsed/refractory (R/R) small cell lung cancer (SCLC). AMG 119 demonstrated robust cellular expansion with long-lasting cell persistence and a favorable exposure-response relationship. AMG 119 has been demonstrated to be clinically safe and well tolerated at the doses tested, with no dose-limiting toxicities (DLTs) reported. This is the first publication of the clinical pharmacology profile of a CAR-T cell therapy in SCLC, with encouraging cellular kinetics data supporting the potential for CAR-T cell therapy in solid tumor space.