Exposure-response relationships of venetoclax in combination with carfilzomib and dexamethasone in relapsed/refractory t(11;14) multiple myeloma patients

Venetoclax is a first in class BCL-2 inhibitor, currently under investigation for the treatment of t(11;14) multiple myeloma (MM). The objective of this analysis was to characterize the exposure-efficacy and exposure-safety relationships of venetoclax when combined with carfilzomib and dexamethasone (VenKd) in t(11;14)-positive relapsed or refractory (R/R) MM patients from a phase 2 study. Fifty-seven patients receiving VenKd or Kd were included in the analysis. Efficacy endpoints included progression-free survival and clinical response rates of overall response, very good partial response or better and complete response or better. Grade ≥ 3 neutropenia, Grade ≥ 3 infections, Grade ≥ 3 treatment-emergent adverse events and any grade serious treatment-emergent adverse events were evaluated. The analysis demonstrated that adding venetoclax to Kd resulted in increased ORR, ≥VGPR and ≥ CR rates compared to the control arm. Within the venetoclax treatment arms (VenKd), no significant exposure-efficacy relationships were observed for ORR and ≥ VGPR rates. Higher ≥ CR rates trended with higher venetoclax exposures. While both 400 mg and 800 mg venetoclax in VenKd arms were generally tolerated, higher rates of Grade ≥ 3 neutropenia were observed with higher venetoclax exposures. Higher venetoclax exposures however were not associated with increased rates of Grade ≥ 3 treatment-emergent adverse events, Grade ≥ 3 infections, or serious treatment-emergent adverse events (any grade). These results confirm the benefit of adding venetoclax to carfilzomib and dexamethasone and support continued evaluation of venetoclax 400–800 mg once daily in this combination in t(11;14)-positive R/R MM patients. NCT02899052 registered April 18, 2017.