Safety of tarlatamab with 6-8-h outpatient versus 48-h inpatient monitoring during cycle 1: DeLLphi-300 phase 1 substudy

Abstract

Background Tarlatamab, a bispecific T-cell engager immunotherapy targeting delta-like ligand 3, has demonstrated promising survival outcomes in small-cell lung cancer (SCLC). Given the risk of cytokine release syndrome (CRS), initial clinical trials incorporated 48-72-h inpatient monitoring in cycle 1. Methods Patients with previously treated SCLC were enrolled into DeLLphi-300 part F, which evaluated the safety of tarlatamab 10 mg every 2 weeks (Q2W) with 6-8-h outpatient monitoring following cycle 1 doses. The primary endpoint, safety, was compared with patients from DeLLphi-300 part A receiving tarlatamab 10 mg Q2W with 48-h inpatient monitoring for cycle 1 doses. Results In cycle 1, the rates of treatment-related adverse events and hospitalizations, including emergency room visits, were similar between outpatient (n = 30) and inpatient (n = 58) groups (93% versus 100% and 27% versus 34%, respectively). The incidence of all grade and serious CRS during cycle 1 was similar between outpatient and inpatient groups (any grade: 60% versus 62%; serious: 17% versus 22%). The median time to CRS resolution was 3 days for both groups. Conclusions Safety outcomes, including hospitalization rates, were similar in this first-in-human study following tarlatamab 10 mg Q2W administration with 6-8-h outpatient versus 48-h inpatient monitoring in cycle 1.