腎細胞癌病人接受Pembrolizumab治療後發生災難性抗磷脂症候群

 – 案例報告

徐震翰¹、黃子豪^1,2,3、黃逸修^1,2,3

¹台北榮民總醫院 泌尿部；²陽明大學醫學院泌尿學科；³書田泌尿學研究中心

 Catastrophic Antiphospholipid Syndrome Following Pembrolizumab Therapy in a Patient with Renal Cell Carcinoma: A Case Report

Chen-Han Hsu¹, Tzu-Hao Huang^1,2,3, Eric Yi-Hsiu Huang^1,2,3

¹Department of Urology, Taipei Veterans General Hospital, Taipei, Taiwan

²Department of Urology, School of Medicine, National Yang-Ming University, Taipei, Taiwan

³Shu-Tien Urological Institute, National Yang-Ming University, Taipei, Taiwan

Introduction:

Pembrolizumab, a programmed death-1 (PD-1) inhibitor, is a mainstay in the treatment of advanced renal cell carcinoma. While immune-related adverse events (irAEs) are frequently encountered, severe autoimmune thrombotic complications remain rare. Catastrophic antiphospholipid syndrome (CAPS) is a life-threatening, fulminant variant of antiphospholipid syndrome characterized by rapidly progressive multi-organ thrombosis and a high mortality rate. Here, we report a rare case of CAPS occurring in the immediate postoperative period after radical nephrectomy in a patient with renal cell carcinoma who had been pre-treated with Pembrolizumab therapy.

Case Report:

A 49-year-old male with a history of hypertension presented in August 2024 with upper abdominal discomfort, poor appetite, and significant weight loss of more than 10 kg over the past three months. A CT scan at a local hospital revealed a left renal mass with tumor thrombus extending into the inferior vena cava (IVC) and regional lymphadenopathy. He was referred to our center, where a biopsy confirmed clear cell RCC with sarcomatoid differentiation. A bone scan was negative, and bilateral tiny lung nodules (0.4 cm) were found on chest CT. Lab results indicated anemia, thrombocytosis, low albumin, and elevated LDH, placing the patient in the IMDC intermediate-risk category.

Given the advanced disease, suspected metastasis, and systemic symptoms, we recommended systemic therapy as the first-line treatment, with the possibility of deferred cytoreductive nephrectomy. Starting in September 2024, the patient tolerated well with Pembrolizumab(200mg) and Lenvatinib(14 mg). After completing four cycles of treatment, follow-up CT revealed significant tumor regression, and the patient's lab results and overall performance improved. As a result, the patient underwent robot-assisted left radical nephrectomy with IVC thrombectomy.

However, after subsequent radical nephrectomy and IVC thrombectomy, he developed fulminant multi-organ failure. He initially suffered from oliguric acute kidney injury (AKI), requiring immediate CVVH and subsequent intermittent hemodialysis. Despite a brief period of stabilization, his condition rapidly deteriorated into decompensated hepatic failure, characterized by progressive jaundice, coagulopathy, and marked liver atrophy on computed tomography. Concurrently, the patient developed respiratory distress and profound consciousness disturbance, requiring endotracheal intubation and mechanical ventilation during ICU readmission. Laboratory investigations revealed severe thrombocytopenia and persistent massive chylous ascites, while infectious screening identified concurrent sepsis with CMV and Aspergillus viremia, further complicating the clinical picture.

Extensive workup for autoimmune etiologies was negative for ANA and ANCA. However, further serologic testing revealed positive anti-β2 glycoprotein I IgG antibodies. Given the rapid sequence of thrombotic-like microvascular insults across the renal, hepatic, and central nervous systems, Catastrophic Antiphospholipid Syndrome (CAPS) was diagnosed.

Pembrolizumab was discontinued, and the patient was treated with corticosteroids, anticoagulation, and supportive care. His condition gradually improved, with resolution of ascites and recovery of hepatic and renal function. Anti-β2 glycoprotein I antibodies became negative in July 2025. Both corticosteroids and warfarin were gradually tapered and successfully discontinued by early 2026. No recurrence was noted at the last follow-up in March 2026.

Conclusions:

Catastrophic antiphospholipid syndrome (CAPS) should be considered in patients receiving Pembrolizumab who develop rapidly progressive multi-organ failure postoperatively, particularly when hepatic and renal dysfunction occur without an obvious etiology. Early recognition and the prompt initiation of immunosuppressive and anticoagulation therapies may significantly improve clinical outcomes.