Dramatic and sustained regression of an inferior vena cava tumor thrombus in a patient with unresectable giant hepatocellular carcinoma following sequential systemic therapy: a case report and literature review

Hepatocellular carcinoma (HCC) with major vascular invasion, particularly inferior vena cava (IVC) tumor thrombus, carries a dismal prognosis and has long been considered a treatment challenge. Although immune checkpoint inhibitors (ICIs) combined with anti-angiogenic agents have become the first-line standard systemic therapy for advanced HCC, data on long-term survival in patients with large tumors complicated by IVC tumor thrombus remain scarce. Herein, we report the case of a 63-year-old male patient with Barcelona Clinic Liver Cancer (BCLC) stage B unresectable HCC in whom an IVC tumor thrombus emerged during first-line therapy, with a baseline Child-Pugh score of 7 (class B) and albumin-bilirubin (ALBI) grade 3. The patient received first-line sintilimab plus the bevacizumab biosimilar IBI305 at an individualized 4-week interval for financial reasons. Early in first-line therapy (January 2023) a new IVC filling defect appeared; multidisciplinary review favored improved visualization of a previously occult thrombus over true progression, and treatment was continued. After twelve cycles, therapy was self-discontinued and the patient remained off treatment for 10.5 months, during which he required admission for massive ascites (at month 3) and the tumor later progressed. Regorafenib was then initiated as a non-standard second-line agent at an individualized reduced dose (80 mg/day, later 80 mg every other day for hand-foot skin reaction). The IVC tumor thrombus regressed completely and the target-lesion sum of diameters decreased by 48.9% from baseline, achieving partial response (PR) per RECIST 1.1 by June 2026. As of June 2026, the patient remains alive more than 4 years from initial detection of the liver mass. This case demonstrates that durable long-term survival can be achieved in patients with giant HCC and IVC tumor thrombus through sequential systemic therapy, even in the setting of treatment interruption. This report provides clinical insight for the management of advanced HCC with major vascular invasion.