Sirolimus Use in Liver Transplant Recipients With Hepatocellular Carcinoma: A Randomized, Multicenter, Open-Label Phase 3 Trial.

BACKGROUND: We investigated whether sirolimus-based immunosuppression improves outcomes in liver transplantation (LTx) candidates with hepatocellular carcinoma (HCC). METHODS: In a prospective-randomized open-label international trial, 525 LTx recipients with HCC initially receiving mammalian target of rapamycin inhibitor-free immunosuppression were randomized 4 to 6 weeks after transplantation into a group on mammalian target of rapamycin inhibitor-free immunosuppression (group A: 264 patients) or a group incorporating sirolimus (group B: 261). The primary endpoint was recurrence-free survival (RFS); intention-to-treat (ITT) analysis was conducted after 8 years. Overall survival (OS) was a secondary endpoint. RESULTS: Recurrence-free survival was 64.5% in group A and 70.2% in group B at study end, this difference was not significant (P = 0.28; hazard ratio [HR], 0.84; 95% confidence interval [95% CI], 0.62; 1.15). In a planned analysis of RFS rates at yearly intervals, group B showed better outcomes 3 years after transplantation (HR, 0.7; 95% CI, 0.48-1.00). Similarly, OS (P = 0.21; HR, 0.81; 95% CI, 0.58-1.13) was not statistically better in group B at study end, but yearly analyses showed improvement out to 5 years (HR, 0.7; 95% CI, 0.49-1.00). Interestingly, subgroup (Milan Criteria-based) analyses revealed that low-risk, rather than high-risk, patients benefited most from sirolimus; furthermore, younger recipients (age ≤60) also benefited, as well sirolimus monotherapy patients. Serious adverse event numbers were alike in groups A (860) and B (874). CONCLUSIONS: Sirolimus in LTx recipients with HCC does not improve long-term RFS beyond 5 years. However, a RFS and OS benefit is evident in the first 3 to 5 years, especially in low-risk patients. This trial provides the first high-level evidence base for selecting immunosuppression in LTx recipients with HCC.

Iron-sulfur cluster N2 of the Escherichia coli NADH:ubiquinone oxidoreductase (complex I) is located on subunit NuoB.

The proton-pumping NADH:ubiquinone oxidoreductase, also called respiratory complex I, couples the transfer of electrons from NADH to ubiquinone with the translocation of protons across the membrane. One FMN and up to 9 iron-sulfur (Fe/S) clusters participate in the redox reaction. There is discussion that the EPR-detectable Fe/S cluster N2 is involved in proton pumping. However, the assignment of this cluster to a distinct subunit of the complex as well as the number of Fe/S clusters giving rise to the EPR signal are still under debate. Complex I from Escherichia coli consists of 13 polypeptides called NuoA to N. Either subunit NuoB or NuoI could harbor Fe/S cluster N2. Whereas NuoB contains a unique motif for the binding of one Fe/S cluster, NuoI contains a typical ferredoxin motif for the binding of two Fe/S clusters. Individual mutation of all four conserved cysteine residues in NuoB resulted in a loss of complex I activity and of the EPR signal of N2 in the cytoplasmic membrane as well as in the isolated complex. Individual mutations of all eight conserved cysteine residues of NuoI revealed a variable phenotype. Whereas cluster N2 was lost in most NuoI mutants, it was still present in the cytoplasmic membranes of the mutants NuoI C63A and NuoI C102A. N2 was also detected in the complex isolated from the mutant NuoI C102A. From this we conclude that the Fe/S cluster N2 is located on subunit NuoB.