Liver transplantation offers excellent long-term survival for hepatocellular carcinoma (HCC) patients who fall within established criteria. For those outside such criteria, or with high-risk pathologic features in the explant, HCC recurrence rates are higher. We conducted a multicenter phase I trial of sorafenib in liver transplantation patients with high-risk HCC. Subjects had HCC outside the Milan criteria (pre- or post-transplant), poorly differentiated tumors, or vascular invasion. We used a standard 3+3 phase I design with a planned duration of treatment of 24 weeks. Correlative studies included the number of circulating endothelial cells (CECs), plasma biomarkers, and tumor expression of p-Erk, p-Akt, and c-Met in tissue micro-arrays. We enrolled 14 patients with a median age of 63 years. Of these, 93% were men and 71% had underlying hepatitis C virus (HCV) and 21% had HBV. The maximum tolerated dose of sorafenib was 200 mg BID. Grade 3-4 toxicities seen in >10% of subjects included leukopenia (21%), elevated gamma-glutamyl transferase (21%), hypertension (14%), hand-foot syndrome (14%) and diarrhea (14%). Over a median follow-up of 953 days, one patient died and four recurred. The mean CEC number at baseline was 21 cells/4 ml for those who recurred, and 80 cells/4 ml for those who did not (p=0.10). Mean soluble vascular endothelial growth factor receptor-2 levels decreased after 1 month on sorafenib (p=0.09), but did not correlate with recurrence. There was a trend for tumor c-Met expression to correlate with increased risk of recurrence. Post-transplant sorafenib was found to be feasible and tolerable at 200 mg PO BID. The effect of post-transplant sorafenib on recurrence-free survival is potentially promising but needs further validation in a larger study.

Cancer-associated fibroblasts (CAF) are a poorly characterized cell population in the context of liver cancer. Our study investigates CAF functions in intrahepatic cholangiocarcinoma (ICC), a highly desmoplastic liver tumor. Genetic tracing, single-cell RNA sequencing, and ligand-receptor analyses uncovered hepatic stellate cells (HSC) as the main source of CAF and HSC-derived CAF as the dominant population interacting with tumor cells. In mice, CAF promotes ICC progression, as revealed by HSC-selective CAF depletion. In patients, a high panCAF signature is associated with decreased survival and increased recurrence. Single-cell RNA sequencing segregates CAF into inflammatory and growth factor-enriched (iCAF) and myofibroblastic (myCAF) subpopulations, displaying distinct ligand-receptor interactions. myCAF-expressed hyaluronan synthase 2, but not type I collagen, promotes ICC. iCAF-expressed hepatocyte growth factor enhances ICC growth via tumor-expressed MET, thus directly linking CAF to tumor cells. In summary, our data demonstrate promotion of desmoplastic ICC growth by therapeutically targetable CAF subtype-specific mediators, but not by type I collagen.