Initial Dose Tarlatamab-Associated Tumour Lysis Syndrome in Small Cell Lung Cancer: A Case Report.

Tumour lysis syndrome (TLS) in solid tumours is rare but may occur in small-cell lung cancer (SCLC) with a high tumour burden. We report a case of fatal TLS following tarlatamab treatment for relapsed SCLC. A 61-year-old woman with limited-stage SCLC developed recurrence with extensive liver metastases after chemoradiotherapy and durvalumab consolidation therapy. Owing to rapid disease progression, an initial 1-mg step-up dose of tarlatamab was administered as second-line treatment. On Day 2, the patient developed mild cytokine release syndrome, which improved with dexamethasone. On Day 6, she suddenly developed respiratory failure and impaired consciousness. Laboratory findings, including elevated lactate dehydrogenase, potassium, phosphorus and uric acid levels with acute kidney injury, suggested TLS and she died later that day. This case demonstrates that tarlatamab can induce fatal TLS even after a single 1-mg dose. Patients with SCLC with extensive liver metastases require careful monitoring and aggressive strategies for TLS prevention.