Anti-myeloma effects of ruxolitinib combined with bortezomib and lenalidomide: A rationale for JAK/STAT pathway inhibition in myeloma patients.

JAK proteins have been linked with survival and proliferation of multiple myeloma (MM) cells; therefore, JAK inhibition could be a therapeutic strategy for MM. We evaluated JAK1 and JAK2 expression in MM patients and the effects of JAK/STAT pathway inhibition on apoptosis, cell cycle, gene and protein expression in RPMI-8226 and U266 MM cell lines. 57% of patients presented overexpression of JAK2 and 27%, of JAK1. After treatment with ruxolitinib and bortezomib, RPMI-8226 and U266 presented 50% of cells in late apoptosis, reduction of anti-apoptotic genes expression and higher number of cells in SubG0 phase. Co-culture with stromal cells protected RPMI-8226 cells from apoptosis, which was reversed by lenalidomide addition. Combination of ruxolitinib, bortezomib and lenalidomide induced 72% of cell death, equivalent to bortezomib, lenalidomide and dexamethasone, combination used in clinical practice. Many JAK/STAT pathway genes, after treatment, had their expression reduced, mainly in RPMI-8226, with insignificant changes in U266. In this scenario, JAK/STAT pathway could pose as a new therapeutic target to be exploited, since it is constitutively active and contributes to survival of MM tumor cells.

de Oliveira MB ，Fook-Alves VL ，Eugenio AIP ，Fernando RC ，Sanson LFG ，de Carvalho MF ，Braga WMT ，Davies FE ，Colleoni GWB ... -  《-》

INCB16562, a JAK1/2 selective inhibitor, is efficacious against multiple myeloma cells and reverses the protective effects of cytokine and stromal cell support.

Li J ，Favata M ，Kelley JA ，Caulder E ，Thomas B ，Wen X ，Sparks RB ，Arvanitis A ，Rogers JD ，Combs AP ，Vaddi K ，Solomon KA ，Scherle PA ，Newton R ，Fridman JS ... -  《NEOPLASIA》

Sequential combination of bortezomib and WEE1 inhibitor, MK-1775, induced apoptosis in multiple myeloma cell lines.

Multiple myeloma (MM) remains incurable due to high rates of relapse after various treatment regimens. WEE1 is a cell cycle related gene that regulates the G2/M checkpoint and promotes cell cycle suspension for consequent DNA repair. To date, there are clinical studies for the evaluation of WEE1 inhibitors in the treatment of solid tumors and studies on cell lines of non-MM hematological tumors. To perform in vitro functional studies to verify the effect of the inhibition of WEE1 on MM cell lines viability and its potential as therapeutic target. WEE1 expression was evaluated in 22 newly diagnosed MM patients and in four MM cell lines, RPMI-8226, U266 and SKO-007 and SK-MM2, by quantitative real-time PCR (qPCR). After treatment with the WEE1 inhibitor (MK-1775), with or without proteasome inhibitor (bortezomib) pretreatment, we assessed cell viability through Prestoblue functional test, microspheres formation in soft agar, and induction of apoptosis and cell cycle alterations by flow cytometry. All MM cell lines showed WEE1 expression by qPCR. RPMI-8226 and U266 showed a 50% reduction in cell viability after 24 h of incubation with MK-1775, at concentrations of 5 μM and 20 μM, respectively. SKO-007 showed dose and time dependence to this drug. Combination therapy with bortezomib and MK-1775 abolished the formation of soft agar microspheres in the RPMI-8226 cell line (also responsive to the use of both drugs) and U266, but SKO-007 was resistant to all drugs, isolated and combined. However, treatment of bortezomib followed by MK-1775 (sequential treatment) versus bortezomib alone showed statistically significant impact on cell lines total apoptosis: 88.8% vs 74.1% in RPMI-8222 (confirmed by cell cycle experiments); 92.5% vs 86.6% in U266; and 60.2% 30.9% on SKO-007 (p < 0.05). The sequential combination of bortezomib and WEE1 inhibitor, MK-1775, induced apoptosis in RPMI-8226, U266, and especially SKO-007 cell lines, more efficiently than the use of the same isolated drugs, highlighting its effect in inhibition of proliferation of tumor cells in MM cell lines. Our data suggest that WEE1 can figure as a MM target and that the sequential combination of bortezomib and MK-1775 may be explored in future clinical trials.

Barbosa RSS ，Dantonio PM ，Guimarães T ，de Oliveira MB ，Fook Alves VL ，Sandes AF ，Fernando RC ，Colleoni GWB ... -  《-》

The role of JAK inhibitors in multiple myeloma.

Ghermezi M ，Spektor TM ，Berenson JR 《-》

The novel JAK inhibitor CYT387 suppresses multiple signalling pathways, prevents proliferation and induces apoptosis in phenotypically diverse myeloma cells.

Monaghan KA ，Khong T ，Burns CJ ，Spencer A ... -  《-》