David K. Imagawa
University of California, USA
David K Imagawa is a Professor of Clinical Surgery and Chief in the Division of Hepatobiliary and Pancreas Surgery/Islet Cell Transplantation in the University of California. His research interest are Liver and pancreatic diseases, bile duct and pancreatic tumor resections, bile duct injuries, biliary reconstruction, minimal invasive treatment of advanced liver tumors, laparascopic, ultrasound guided radiofrequency ablation, biliary reconstruction, pathogenesis of chronic rejection, liver cancer, hepatocellular carcinoma, liver tumor, post transplant hyperlipidemia, clinical trials of novel chemotherapeutic agents, Therasphere, Cirtex, Metabasis, gene therapy for immunosuppression, reperfusion injury in transplantation, islet cell transplantation for complicated Diabetes Mellitus Type I, mechanism of immunomodulation, hepatitis screening, organ donation.
Sorafenib is the only FDA approved agent that has been shown to prolong survival in unresectable hepatocellular carcinoma (HCC). The recommended dose is 400mg BID. Our anecdotal experience has shown that the majority of our Asian-American patient populations are unable to tolerate this recommendation. This is a pilot study aimed at evaluating a potential difference in pharmacokinetics (PK) of Sorafenib metabolism between the Asian-American (AA) and Non-Asian (NA) patient population. A cohort of 23 patients completed the study. The PK of Sorafenib and its main metabolite M-2 were analyzed at 0, 1, 2, 4, 9 and 12 hours respectively. A subset analysis comparing high dose (>400mg daily) vs. low dose (≤400mg daily), high body surface area (BSA>1.9) vs. low body surface area (BSA≤1.9) and AA vs. NA patients was preformed. 18 patients were in the low dose cohort with 2 mortalities (749 and 283 days) and 1 patient achieving complete response (201 days). There were no deaths in the high dose group. There were no significant differences in the PK of Sorafenib and M-2 between the high and low dose groups nor the high and low BSA groups. Despite the difference in dose, the mean Sorafenib AUC and Cmax of the low dose group was at least 70% of the high dose group at steady state. Furthermore, the mean Sorafenib AUC and Cmax of the low BSA cohort was at least 75% of the high BSA group at steady state. There were no significant differences in the PK between the AA and NA groups. Our analysis reveals a trend towards comparable PK of Sorafenib and M-2 metabolite despite lower doses and lower BSA. These findings suggest that a lower, more tolerable dose of Sorafenib in AA patients may not compromise drug efficacy. Large, population based studies are needed to validate these findings.