Early Pseudoprogression After Tarlatamab in Small-Cell Lung Cancer: A Case Report

Area of Science:

• Oncology
• Immunotherapy
• Pharmacology

Background:

• Pseudoprogression is a known phenomenon in cancer immunotherapy.
• Tarlatamab is a bispecific T-cell engager for small-cell lung cancer (SCLC).
• Pseudoprogression has not been previously reported with tarlatamab.

Purpose of the Study:

• To report a case of potential pseudoprogression after tarlatamab treatment in SCLC.
• To investigate the clinical course and imaging findings associated with early tarlatamab administration.
• To explore the relationship between radiographic changes, biomarkers, and treatment response.

Main Methods:

• Case report of a 57-year-old woman with extensive-stage SCLC and SIADH.
• Administration of tarlatamab as third-line therapy.
• Serial imaging (Day 7 and Day 13) and pro-gastrin-releasing peptide (pro-GRP) monitoring.

Main Results:

• Initial imaging showed tumor swelling and pleural effusion, mimicking progression.
• Cytology remained negative, and serum sodium levels rose.
• Subsequent imaging demonstrated regression of thoracic and hepatic lesions.
• Pro-gastrin-releasing peptide (pro-GRP) levels decreased.

Conclusions:

• This case suggests early pseudoprogression may occur with tarlatamab in SCLC.
• Transient radiographic changes followed by tumor regression may indicate treatment efficacy.
• Monitoring biomarkers like pro-GRP alongside imaging is crucial for interpreting treatment response.