Entospletinib drug interaction profile and mass balance.

e14097Background: Entospletinib (ENTO), a Syk inhibitor, has shown clinical activity in R/R CLL subjects. In vitro, ENTO inhibited OATP1B1/1B3, BCRP, P-gp and UGT1A1; ENTO metabolism is mediated by CYP2C9 and CYP3A. These studies evaluate the drug interaction (DDI) profile and mass balance (MB) of ENTO. Methods: Healthy subjects received ENTO alone, or with cobicistat (COBI; CYP3A inhibitor), rifampin (RIF; CYP3A inducer), fluconazole (FLU; CYP2C9/CYP3A inhibitor), rosuvastatin (ROS; OATP1B1/1B3, BCRP substrate) or digoxin (DIG, P-gp substrate). For the MB study, healthy subjects received a single dose of ENTO containing [14C]-labeled ENTO. Results: DDI results are shown below. ENTO was extensively metabolized to 14 metabolites in the MB study; ~91% and ~2% of the dose was recovered in feces and urine, respectively. The majority of circulating radioactivity was associated with unchanged ENTO. ENTO was generally well tolerated in these studies. Conclusions: Co-administration with strong CYP3A inducers may ...