The Synergistic Effect of Portal Venous Supply Control and Immunotherapy in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most common solid malignant tumors and the main cause of cancer-related deaths worldwide. The main treatment method for patients with unresectable or advanced HCC (such as patients with vascular invasion, distant metastasis, or tumor-related symptoms) is systemic therapy such as immunotherapy combined with targeted drugs. The median OS of patients treated with first-line bevacizumab (T)+atilizumab (A) was 19.2 months, and the ORR was 30%; The median OS was 22 months and the ORR was 36% when the Lenvatinib+Pembrolizumab (K-drug) regimen was used in the second-line treatment of patients with unresectable HCC. At present, the combination of domestic PD-L1 monoclonal antibody, Camrelizumab, and VEGFR-2 inhibitor, Apatinib, shows great potential in the treatment of Chinese patients with unresectable HCC. Phase II data shows that the ORR, DCR, mPFS, and mOS for first-line treatment are 34%, 77%, 5.7 months, and 20.3 months respectively.

However, the benefits for patients are still very limited, and the clinical treatment of non-resectable HCC is facing serious challenges. Therefore, it is necessary to take a reasonable multidisciplinary comprehensive treatment strategy, to establish a new effective treatment plan and further improve the prognosis and quality of life of patients.

The anti-vascular treatment of HCC is the basis of immunotherapy and an important trigger and intensifier. The reason and mechanism are that hepatocellular carcinoma can be secondary to liver injury caused by various reasons, such as chronic alcohol consumption, chronic hepatitis B and C infection, non-alcoholic fatty liver, etc., but all of them are manifested by increased blood vessels and significant vascular abnormalities, which suggests that blood supply plays an important role in the occurrence and development of HCC. A large number of targeted anti-vascular drugs have been used in the treatment of hepatocellular carcinoma. Angiogenesis inhibitors can specifically inhibit VEGF-mediated dendritic cell maturation disorder, promote antigen presentation and T cell immune response to tumor antigen; At the same time, it antagonizes angiogenesis, blocks tumor blood supply, normalizes tumor blood vessels, and increases T cell infiltration in tumor cells.

The hepatic artery is the main blood supply source of the tumor, so angiogenesis inhibitors often combine with TACE to directly and effectively block the blood supply of the tumor, which can not only effectively inhibit angiogenesis around the tumor, but also delay the progress of tumor and thus improve the effect of tumor treatment. It is noteworthy that portal vein blood flow also plays an important role in the occurrence and development of HCC.

Angiogenesis inhibitors can directly or indirectly affect the portal vein blood flow and improve the prognosis. It has been reported in the literature that angiogenic inhibitors such as sorafenib and lenvatinib can significantly reduce portal vein pressure and effectively prolong the survival period of advanced HCC.

Multiple blood supply blockages also show certain therapeutic significance. In post-line treatment, dual/multiple anti-vascular therapies show therapeutic effects. For example, the multi-target anti-vascular drug regorafenib can be used as the second-line drug after the first-line treatment of sorafenib. The median survival period of sorafenib+regorafenib second-line treatment is 24 months.

The response rate of targeted immunotherapy is higher in advanced patients with portal vein tumor thrombus. Not only does the tumor focus shrink, but the tumor thrombus also shrinks or even disappears. This may be because the lack of blood supply in the portal vein further reduces the blood supply of the tumor and tumor thrombus, thus promoting the response to systemic therapy.

In our previous clinical practice and research, we found that the control of portal vein blood flow on the affected side may have synergistic anti-tumor effects. The advanced patients treated with targeted immunotherapy combined with portal vein blood supply control, such as portal vein embolization (PVE), showed a good treatment response. In the future, while the volume of the residual liver increased, the tumor focus was significantly reduced. The patients obtained the opportunity of surgical resection, and some patients even achieved complete response (CR).

Embolization of the portal vein of the affected liver segment leads to an increase in the blood supply of the residual liver in the future, and realizes a rapid increase in the volume of the residual liver in the future, so as to ensure the quality and prognosis of hepatectomy, which is a common method for patients with early liver cancer before hepatectomy.

At present, there is no study on the use of a portal vein blood supply control combined system for the treatment of unresectable HCC conversion. Based on the current research and clinical practice, we propose a hypothesis that strengthening blood supply control is conducive to the conversion treatment of HCC, and controlling the blood supply of the portal vein has an important synergistic effect on the treatment of unresectable HCC. Portal vein blood supply control combined with TACE and targeted immunotherapy can further enhance the conversion rate of unresectable HCC, bring more opportunities for patients' subsequent surgery or local treatment, and help to prolong the survival period of patients.