Rapid-onset Severe Cytokine Release Syndrome With Marked Interleukin-6 Increase and Acute Liver Injury After the First Tarlatamab Dose in SCLC: Case Report.

Tarlatamab is a novel bispecific T-cell engager therapy with promising efficacy in patients with previously treated extensive-stage SCLC. Cytokine release syndrome (CRS) is the most common adverse event related to tarlatamab, although severe CRS remains rare, and grade 3 or higher adverse events have been reported to be less common with tarlatamab than with chemotherapy. Available clinical data on severe adverse events associated with tarlatamab remain limited. Herein, we report a case of a 55-year-old woman with extensive-stage-SCLC who was treated with tarlatamab. Severe CRS and liver injury rapidly developed in the patient after the first tarlatamab dose, which led to treatment discontinuation. This report also presents the temporal changes in serum interleukin-6 levels, highlighting its potential utility as a biomarker for the onset and severity of CRS.