IBL-202 is synergistic with venetoclax in CLL under in vitro conditions that mimic the tumor microenvironment

Abstract

The B-cell receptor signaling pathway and dysregulation of the Bcl-2 family of proteins play crucial roles in the pathogenesis of chronic lymphocytic leukemia (CLL). Despite significant advances in the treatment of the disease, relapse and drug resistance are not uncommon. In the current study, we investigated the dual PI3/PIM kinase inhibitor IBL-202 in combination with venetoclax as a treatment option for CLL using both primary CLL cells and TP53-deficient OSU-CLL cells generated using the CRISPR-Cas9 system. IBL-202 and venetoclax were highly synergistic against primary CLL cells cocultured with CD40L fibroblasts (combination index [CI], 0.4, at a fractional effect of 0.9) and TP53-knockout (KO) OSU-CLL cells (CI, 0.5, at a fractional effect of 0.9). Synergy between the drugs was consistent, with a significant (P < .05) reduction in the 50% inhibitory concentration for both drugs. IBL-202 and venetoclax in combination induced cell-cycle arrest and slowed the proliferation of both wild-type and TP53-KO cell lines. The drug combination inhibited AKT phosphorylation, reduced expression of Bcl-xL and NF-κB, and increased the Noxa/Mcl-1 ratio. Downregulation of CXCR4 was consistent with inhibition of the SDF-1α–induced migratory capacity of CLL cells. Synergy between IBL-202 and venetoclax against primary CLL cells cultured under conditions that mimic the tumor microenvironment suggests this drug combination may be effective against CLL cells within the lymph nodes and bone marrow. Furthermore, the efficacy of the combination against the TP53-KO OSU-CLL cell line suggests the combination may be a highly effective treatment strategy for high-risk CLL.

Evaluation of the novel therapeutic anti‐CCR7 antibody CAP‐100 as an add‐on therapy in chronic lymphocytic leukemia patients receiving venetoclax

“…When compared to controls (vehicle/DMSO) venetoclax did not modify the proportion of CCR7‐positive CLL cells, however, the inhibitor lowered MFI‐CCR7 down ∼30% in the range [10–1000 nM] (Figure 2A,B and Supplementary Figure S1), although this change did not reach statistical significance at any of the tested doses [for example, mean ± SE of MFI‐CCR7 in DMSO versus venetoclax (100 nM) = 40,186 ± 5843 versus 26,947 ± 4738; p > 0.05]. Likewise, venetoclax also reduced surface levels of CXCR4 reaching in this occasion a down‐modulation rate of ∼70% and statistical significance in the range 10–1000 nM [for example, mean ± SE of MFI‐CXCR4 in DMSO versus venetoclax (100 nM) = 17,105 ± 2297 versus 5463 ± 655.3; p < 0.01], as previously described 9 …”

“…Fresh PBMC, containing at least 80% of CLL cells, were obtained from treatment‐naïve patients ( n = 3), isolated by gradient centrifugation, and cultured in RPMI‐1640 medium supplemented with 10% fetal bovine serum (FBS). Cells were incubated for 24 h in the presence of venetoclax (provided by HULP Pharmacy Department) at different final concentrations [0 (vehicle, DMSO); 0.01; 0.1; 1; 10; 100; 1000 nM], in agreement with standard concentration ranges published elsewhere 9–11 . Since Shen et al showed venetoclax (10 nM) to significantly down‐regulate CXCR4 expression in primary CLL cells cultured in vitro, 9 we included the study of this chemokine receptor as reference.…”

“…Cells were incubated for 24 h in the presence of venetoclax (provided by HULP Pharmacy Department) at different final concentrations [0 (vehicle, DMSO); 0.01; 0.1; 1; 10; 100; 1000 nM], in agreement with standard concentration ranges published elsewhere. [9][10][11] Since Shen et al showed venetoclax (10 nM) to significantly down-regulate CXCR4 expression in primary CLL cells cultured in vitro, 9 we included the study of this chemokine receptor as reference. After 24 h, the proportion of non-viable 7-AAD þ CLL cells were determined by flow cytometry.…”

In Vitro and In Vivo Models of CLL–T Cell Interactions: Implications for Drug Testing

“…Figure 2. Effects of CD40 pathway on drug responses in CLL cells[21,23,34,42,60,62,63,67,78,[85][86][87][88][89][90][91][92][93][94][95][96].…”