Chapter 22: The RAPID Concept: Pushing the Boundary in Resectability in Liver Transplant Oncology

AUXILIARY LIVER TRANSPLANTATION FOR FULMINANT LIVER FAILURE: A FOUNDATION FOR PARTIAL LIVER ALLOGRAFTS

• Auxiliary liver grafts are temporary allografts transplanted to provide hepatocyte function during acute liver failure (ALF) in an otherwise previously healthy patient expected to recover endogenous liver function through normal liver regeneration. This approach can potentially spare the need for future immunosuppression, as the auxiliary graft can be allowed to reject once native liver function recovers.

• In 1990 heterotopic auxiliary liver transplantations (HALTs) were described to provide a hepatic mass for patients with ALF,¹ yet were marred by high rates of mortality and complications, stemming in part from venous outflow obstruction and lack of accommodating heterotopic locations.

• However, with further refinement, auxiliary partial orthotopic liver transplantation (APOLT) improved the previously unforgiving rates of primary nonfunction and allograft failure, with small European experiences demonstrating parity between orthotopic liver transplantation (OLT) and APOLT.^2,3

• APOLT encompasses the transplantation of a left graft or left lateral section to a patient in ALF. A left lateral sectionectomy is performed to accommodate the graft and provide adequate venous drainage. The transplant allograft bridges the patient through ALF until the native liver can recover. Over time, immunosuppression can be slowly weaned, such that the transplanted allograft is rejected and involutes.⁴

• Yet despite improvements in technique and strategy, auxiliary liver transplantation has failed to garner widespread adoption, even within the small subset of patients who present with fulminant, yet recoverable liver failure, as in patients with acetaminophen or mushroom overdoses.

• APOLT served as the technical basis for the RAPID (resection and partial liver segment two-thirds transplantation with delayed total hepatectomy) concept in liver transplantation, with similar technique in anastomosis and approach (Fig. 22-1).

ALPPS AND ACCELERATED LIVER HYPERTROPHY IN HEPATIC ONCOLOGY

• In 2012, a novel concept of the two-state hepatectomy combining parenchymal partition and deportalization of the right lobe of the liver for unresectable tumor(s) (ALPPS) demonstrated remarkable hypertrophy of the left liver remnant in patients with unresectable liver tumors but with small left lateral sections.⁵

• In patients with anticipated small future liver remnants, this approach offered accelerated hypertrophy of the future liver remnant (FLR) compared to conventional two-stage hepatectomies and demonstrated higher rates of achieving curative-intent resection.⁶

• Preclinical data suggest the coupling of a deportalized segment of liver, as well as the acute inflammatory response of liver parenchymal injury, results in cytokine release, principally interleukin 6, which induces hepatocyte hypertrophy and hyperplasia.⁷

• The early experience with ALPPS demonstrated that patient selection is key to good outcomes and adequate liver hypertrophy of the FLR.⁸

• Optimal candidate selection incorporates both patient and tumor characteristics. Reports of the International ALPPS Registry, for example, suggest the ideal patient has good performance status and normal liver function as measured by Model for End-Stage Liver ...