Extensive-stage small cell lung cancer: multi-line treatment complicated by glucocorticoid-refractory immune-related cystitis

What happened, in summary

This 56-year-old man presented in August 2023 with 2 weeks of cough and sputum production. He had a 30-year smoking history. Chest CT showed a soft-tissue mass in the right hilar region, and bronchoscopy biopsy confirmed small-cell neuroendocrine carcinoma. He was diagnosed with right-lung small-cell lung cancer, cT4N3M1, extensive stage. First-line treatment began on 12 September 2023 with durvalumab, etoposide, and cisplatin for 4 cycles, followed by durvalumab maintenance. He had partial response after cycle 2, but progression after cycle 10, giving 9 months of progression-free survival. Re-treatment with durvalumab, etoposide, and cisplatin led to abdominal progression after 2 cycles. Tarlatamab was then given for 3 cycles, again followed by abdominal progression. Fourth-line treatment used irinotecan, tislelizumab, and anlotinib, then anlotinib alone, then irinotecan plus anlotinib, and finally anlotinib maintenance. This produced partial response after cycle 2 but was complicated by grade 3 tislelizumab-related immune cystitis. Infection, tumor infiltration, and chemotherapy injury were excluded. Steroids helped only temporarily, and symptoms recurred during tapering. Bladder biopsy showed immune-mediated T-cell-predominant inflammation. Prednisone plus mycophenolate mofetil led to urinary symptom relief within 1 week and normalized urine testing by 8 weeks. The cancer later progressed in the liver; lurbinectedin plus hepatic interventional therapy was followed by new brain metastasis, and temozolomide plus olaparib with hepatic interventional therapy had only 2 months of benefit. As of December 2025, care had shifted to palliative symptom management. The case also highlights that immune toxicity and cancer progression can overlap during late-line treatment, requiring both symptom control and careful treatment adjustment.