Evaluation of the drug disposition of RO7049389 with in vitro data and human mass balance supported by physiologically based pharmacokinetic modelling.

AIMS: RO7049389 (linvencorvir) is a developmental oral treatment for chronic hepatitis B virus infection. The aim of this work was to conduct mass balance (MB) and absolute bioavailability (BA) analyses in healthy volunteers, alongside in vitro evaluations of the metabolism of RO7049389 and a major circulating active metabolite M5 in human hepatocytes, and physiologically based pharmacokinetic (PBPK) modelling to refine the underlying drug disposition paradigm. METHODS: Participants in the clinical study (MB: Caucasian, male, n = 6; BA: Caucasian and Asian, male and female, n = 16, 8 in each ethnic groups) received oral [14 C] or unlabelled RO7049389 (600/1000 mg) followed by 100 µg intravenous [13 C]RO7049389. Metabolic pathways with fractions metabolized-obtained from the in vitro incubation results of 10 µM [14 C]RO7049389 and 1 µM M5 with (long-term cocultured) human hepatocytes in the absence and presence of the cytochrome P450 3A4 (CYP3A4) inhibitor itraconazole-were used to complement the PBPK models, alongside the clinical MB and BA data. RESULTS: The model performance in predicting the pharmacokinetic profiles of RO7049389 and M5 aligned with clinical observations in Caucasians and was also successfully applied to Asians. Accordingly, the drug disposition pathways for RO7049389 were postulated with newly characterized estimates of the fractions: biliary excretion by P-glycoprotein (~41%), direct glucuronidation via uridine 5'-diphosphoglucuronosyltransferase 1A3 (~11%), hexose conjugation (~6%), oxidation by CYP3A4 (~28%) and other oxidation reactions (~9%). CONCLUSION: These results support the ongoing clinical development program for RO7049389 and highlight the broader value of PBPK and MB analyses in drug development.

Transplantation in adults with primary hyperoxaluria: single unit experience and treatment algorithm.

BACKGROUND: Kidney transplantation alone in Primary Hyperoxaluria is associated with a high rate of recurrence and in many cases early graft loss. Liver transplantation offers the possibility of correcting the metabolic defect. MATERIAL/METHODS: A retrospective review of five cases of Primary Hyperoxaluria managed at a major transplant unit was performed. RESULTS: The 5 patients had a mean age of 32.2 years (range 28-40) at time of first transplantation. 3 patients had kidney only transplants (one live donor, 2 deceased donor) and 2 had segmental liver followed by delayed kidney transplantation. All 3 kidney alone failed and one is now awaiting a live donor transplant, one underwent kidney alone retransplantation (failed 5 years later) and one had a combined deceased donor liver and kidney transplantation (remains well at 4 years). The 2 segmental liver sequential kidney transplant recipients remain well at 1 year and 3 years. CONCLUSIONS: Combined liver-kidney transplantation may be a better choice as the primary transplant procedure. The indication and timing for pre-emptive liver or liver followed by delayed kidney transplantation remains a matter of debate.