A Case of Acalculous Cholecystitis During Lenvatinib Plus Pembrolizumab Therapy for Advanced Renal Cell Carcinoma

ABSTRACT Introduction Lenvatinib plus pembrolizumab is a standard first‐line therapy for advanced renal cell carcinoma (RCC), and acute acalculous cholecystitis is a rare adverse event. Case Presentation A 60‐year‐old woman with metastatic TFE3‐positive non–clear cell RCC, classified as poor risk by the International Metastatic RCC Database Consortium (IMDC) criteria, started pembrolizumab plus lenvatinib after palliative radiotherapy for cervical spine metastasis. Lenvatinib was initiated at 8 mg and escalated to 12 mg, achieving tumor shrinkage. Nine days after starting cycle 4, she developed fever and right upper quadrant pain. Computed tomography demonstrated gallbladder distension and wall thickening without gallstones, consistent with acute acalculous cholecystitis. Lenvatinib was interrupted, and intravenous piperacillin/tazobactam was administered; her symptoms improved without drainage. Lenvatinib was resumed at 8 mg with pembrolizumab, and no recurrence occurred. Conclusion Early recognition and temporary interruption of lenvatinib with antibiotics may allow cautious rechallenge.