Figure 1.

S63845 strongly synergizes with venetoclax in vitro. (A) Multiple myeloma (MM) cell lines were exposed to increasing doses of S63845+venetoclax for 48 hours (h), using a constant drug ratio combination design for each cell line. Apoptosis induction was analyzed by flow cytometry after Annexin-V binding and propidium iodide micromolar staining as represented in the graphs, and combination indices (CI) were calculated with the Calcusyn software (see also Online Supplementary Figure S2). A CI of 1 indicates an additive effect, CI <1 a synergistic effect and CI<1 antagonism. (B) MM.1S cells were treated with S63845 50 nM and venetoclax 2.5 nM for 3, 6, 12, 24 and 48 h, and the induction of apoptosis was assessed at indicated time points. (C) Bone marrow cells from eight MM patients were incubated with S63845 and venetoclax as single agents and in combination at indicated doses for 24 h. Apoptosis induction was analyzed by flow cytometry after Annexin-V binding in plasma cells (CD38^+bright, CD45^−/low, SSC^{low/intermediate}, CD56−/+) and lymphocytes (CD45⁺⁺, SSC^low).