Liver transplantation for unresectable malignancies: Beyond hepatocellular carcinoma

Vascular damage and excessive proliferation compromise liver function after extended hepatectomy in mice

BACKGROUND AND AIMS

Surgical resection remains the gold standard for liver tumor treatment, yet the emergence of postoperative liver failure, known as the small-for-size syndrome (SFSS), poses a significant challenge. The activation of hypoxia sensors in an SFSS liver remnant initiated early angiogenesis, improving the vascular architecture, safeguarding against liver failure, and reducing mortality. The study aimed to elucidate vascular remodeling mechanisms in SFSS and their impact on hepatocyte function and subsequent liver failure.

APPROACH AND RESULTS

Mice underwent extended partial hepatectomy to induce SFSS, with a subset exposed to hypoxia immediately after surgery. Hypoxia bolstered posthepatectomy survival rates. The early proliferation of liver sinusoidal cells, coupled with recruitment of putative endothelial progenitor cells, increased vascular density, improved lobular perfusion, and limited hemorrhagic events in the regenerating liver under hypoxia. Administration of granulocyte colony-stimulating factor in hepatectomized mice mimicked the effects of hypoxia on vascular remodeling and endothelial progenitor cell recruitment but failed to rescue survival. Compared to normoxia, hypoxia favored hepatocyte function over proliferation, promoting functional preservation in the regenerating remnant. Injection of Adeno-associated virus serotype 8-thyroxine-binding globulin-hepatocyte nuclear factor 4 alpha virus for hepatocyte-specific overexpression of hepatocyte nuclear factor 4 alpha, the master regulator of hepatocyte function, enforced functionality in proliferating hepatocytes but did not rescue survival. The combination of hepatocyte nuclear factor 4 alpha overexpression and granulocyte colony-stimulating factor treatment rescued survival after SFSS-setting hepatectomy.

CONCLUSIONS

In summary, SFSS arises from an imbalance and desynchronized interplay between functional regeneration and vascular restructuring. To improve survival following SFSS hepatectomy, it is essential to adopt a 2-pronged strategy aimed at preserving the function of proliferating parenchymal cells and simultaneously attenuating vascular damage.

Liver Transplantation for Nonresectable Colorectal Liver Metastases (CRLM)

Transplantation represents the most radical locoregional therapy through removal of the liver, associated vasculature and locoregional lymph nodes, and replacing it with an allograft. Recent evidence has demonstrated that transplantation for unresectable CRLM is feasible with acceptable post-transplant outcomes in a highly selected cohort of patients. Controversy exists regarding whether transplantation is an appropriate treatment for such patients, due to concerns regarding disease recurrence in the transplanted graft in an immunosuppressed recipient along with utilising a donor liver which are in short supply. Expanding the indications for liver transplantation may also limit access for other patients with end-stage liver disease having ethical implications due to the effect of increasing the waiting list. In this review, we summarise the current evidence for liver transplantation in patients with nonresectable CRLM and highlight unresolved controversies and future directions for this type of treatment.

Transplant oncology - Current indications and strategies to advance the field

Liver transplantation (LT) was originally described by Starzl as a promising strategy to treat primary malignancies of the liver. Confronted with high recurrence rates, indications drifted towards non-oncologic liver diseases with LT finally evolving from a high-risk surgery to an almost routine surgical procedure. Continuously improving outcomes following LT and evolving oncological treatment strategies have driven renewed interest in transplant oncology. This is not only reflected by constant refinements to the criteria for LT in patients with HCC, but especially by efforts to expand indications to other primary and secondary liver malignancies. With new patient-centred oncological treatments on the rise and new technologies to expand the donor pool, the field has the chance to come full circle. In this review, we focus on the concept of transplant oncology, current indications, as well as technical and ethical aspects in the context of donor organs as precious resources.

Rare Malignant Indications for Liver Transplantation: A Collaborative Transplant Study Report

Introduction: Hepatocellular carcinoma (HCC) is by far the leading malignant indication for liver transplantation (LT). Few other malignancies, including cholangiocellular carcinoma (CCC), metastases from neuroendocrine tumors (NET), and sarcomas of the liver (LSAR), also are commonly accepted indications for LT. However, there is limited information on their outcome after LT.

Methods: Graft and patient survival in 14,623 LTs performed in patients with hepatocellular carcinoma, CCC, NET, and LSAR from 1988 to 2017 and reported to the Collaborative Transplant Study were analyzed.

Results: The study group consisted of 13,862 patients who had HCC (94.8%), 498 (3.4%) who had CCC, 100 (0.7%) who had NET, and 163 (1.1%) who had LSAR. CCC patients showed a 5-year graft survival rate of 32.1%, strikingly lower than the 63.2% rate in HCC, 51.6% rate in NET, and 64.5% rate in LSAR patients (P < 0.001 for all vs. CCC). Multivariable Cox regression analysis revealed a significantly higher risk of graft loss and death due to cancer during the first five post-transplant years in CCC vs. HCC patients (HR 1.77 and 2.56; P < 0.001 for both). The same risks were increased also in NET and LSAR patients but did not reach statistical significance.

Conclusion: Among patients with rare malignant indications for LT, CCC patients showed significantly impaired graft as well as patient survival compared to HCC patients. The observed differences might challenge traditional decision-making processes for LT indication and palliative treatment in specific hepatic malignancies.