Conversion Liver Resection for Hepatocellular Carcinoma with Portal Vein Tumor Thrombus after Single Tremelimumab Regular Interval Durvalumab Regimen as a Second-Line Therapy: A Case Report

INTRODUCTION: Hepatocellular carcinoma (HCC) is a leading cause of cancer-related mortality, with limited treatment options for advanced, unresectable cases. Although immune checkpoint inhibitors (ICI), particularly the combination of atezolizumab plus bevacizumab (Atezo+Bev), have improved outcomes, many patients ultimately experience disease progression. The single tremelimumab regular interval durvalumab (STRIDE) regimen has emerged as a promising alternative, yet evidence of its efficacy as a second-line therapy remains limited. CASE PRESENTATION: A 74-year-old man presented with recurrent HCC and liver cirrhosis complicated by portal vein tumor thrombosis (PVTT). Following 2 cycles of Atezo+Bev and 1 additional cycle of atezolizumab monotherapy, the tumor progressed rapidly. The patient was subsequently treated with dual ICIs (durvalumab and tremelimumab) under the STRIDE regimen, resulting in significant tumor shrinkage and normalization of serum tumor markers. After 4 cycles of STRIDE, conversion surgery was performed, including segment VI resection and portal vein branch thrombectomy. Histopathological analysis revealed >95% tumor necrosis and confirmed R0 resection. CONCLUSIONS: This case illustrates the importance of a multidisciplinary approach in the treatment of advanced HCC and shows that a successful response to the STRIDE regimen, even as a second-line therapy can enable curative conversion surgery while maintaining safety and tolerability in patients with limited hepatic reserve.