Exposure-Response Analyses of the Effects of Venetoclax, a Selective BCL-2 Inhibitor, on B-Lymphocyte and Total Lymphocyte Counts in Women with Systemic Lupus Erythematosus.

backgroundVenetoclax is a selective inhibitor of B-cell lymphoma-2, which plays a role in the development of various autoimmune diseases including systemic lupus erythematosus. The aim of these analyses was to quantify the exposure-response relationship for venetoclax effects on B-lymphocyte and total lymphocyte counts as pharmacodynamic markers of efficacy and safety, respectively, in women with systemic lupus erythematosus. The developed modeling framework was also used to evaluate venetoclax effects following cyclic, continuous, or induction/maintenance dosing paradigms as potential dosing alternatives in systemic lupus erythematosus.

methodsSerial pharmacokinetic and lymphocyte count data from 73 women enrolled in a phase I study of venetoclax (single doses of 10-500 mg or two cycles of 30-600 mg or placebo once daily for 7 days followed by a 21-day washout) were analyzed using a sequential population pharmacokinetic/pharmacodynamic modeling approach. Simulations to evaluate changes in B-lymphocyte and total lymphocyte counts following different venetoclax dosing scenarios were conducted.

resultsEffect of venetoclax plasma exposures on B lymphocytes was described using an indirect linear response model and on total lymphocytes using a maximal response (E

conclusionsVenetoclax treatment in women with systemic lupus erythematosus was associated with exposure-dependent reductions in B lymphocytes, and to a lesser extent, total lymphocyte counts. Results from this study support evaluation of B-cell lymphoma-2 inhibitors as potential therapies for the treatment of systemic lupus erythematosus. CLINICALTRIALS.GOV: NCT01686555.