Lung cancer treated with tislelizumab: rare fluid buildup around the lung as a side effect

What happened, in summary

A 60-year-old man had a mass in the lower part of his right lung found during a routine examination in March 2023. Bronchoscopy confirmed lung squamous cell carcinoma. He received 4 cycles of tislelizumab, nab-paclitaxel, and cisplatin before surgery. Cisplatin was stopped after the fourth cycle because it suppressed his bone marrow. More than 3 months later, he underwent removal of the right lower-lobe tumor in July 2023.

After surgery, maintenance treatment included 1 cycle of nab-paclitaxel and 4 cycles of tislelizumab. Tislelizumab was stopped in October 2023 after he developed treatment-related inflammation in the lungs. A recurrence at the bronchial stump was found in December 2023. He then received concurrent chemotherapy and radiation for 2 months, and follow-up scans showed stable disease.

In August 2024, 10 months after tislelizumab had ended, fluid built up around the right lung. Because this could have represented cancer progression, he underwent repeated drainage procedures, which removed a total of about 2,000 mL of fluid. Repeated fluid tests found no cancer cells or infection. Thoracoscopy and pleural biopsies also found inflammation but no malignancy.

With cancer progression and infection not demonstrated, a delayed immune-related pleuritis was suspected. Methylprednisolone 40 mg daily was started in September and then gradually reduced. The pleural fluid resolved within 10 days. His lung cancer remained stable during the next 15 months of follow-up.

The inflammation appeared long after immunotherapy had stopped, so repeated testing was essential before steroids were used instead of more cancer treatment.