BMS-345541 dose-dependently inhibits the TNF-α-stimulated phosphorylation of IκBα in THP-1 monocytic cells with an IC50 of ~4 μM. BMS-345541 inhibits lipopolysaccharide-stimulated tumor necrosis factorα, interleukin-1β, interleukin-8, and interleukin-6 in THP-1 cells with IC50 values in the 1- to 5 μM range. BMS-345541 binds in a mutually exclusive manner with respect to a peptide inhibitor corresponding to amino acids 26 - 42 of IκBα with Ser-32 and Ser-36 changed to aspartates and in a non-mutually exclusive manner with respect to ADP. BMS-345541 binds to similar allosteric sites on IKK-1 and IKK-2, which then affects the active sites of the subunits differently. ^[1] BMS-345541 affects several mitotic cell cycle transitions, including mitotic entry, prometaphase to anaphase progression and cytokinesis. Adding BMS-345541 to the cells released form arrest in G-phase blocks the activation of Aurora A, B, and C, Cdk1 activation and histone H3 phosphorylation. Treatment of the mitotic cells with BMS-345541 results in precocious cyclin B1 and securin degradation, defective chromosome separation and improper cytokinesis. BMS-345541 is also found to override the spindle checkpoint in nocodazole-arrested cells. These effects are not primarily due to a direct inhibitory effect of BMS-345541 on mitotic kinases such as Cdk1, Aurora A or B, Plk1 or NEK2. ^[2] BMS-345541 (10 μM) inhibits growth of Normal human epidermal melanocytes, and metastatic melanoma cells (SK-MEL-5, A375, and Hs 294T) by 96% and 99% at 72h, respectively. Application of 100 μM of BMS-345541 to SK-MEL-5 cell culture results in 87% apoptotic cells at 24 h through caspase-independent and AIF-dependent mitochondria-mediated manner. BMS-345541 treatment (10 μM) results in 76% and 95% reduction in IKK activities and NF-kB activity, as well as CXCL1 production. ^[3] BMS-345541 inhibits the growth of T-cell acute lymphoblastic leukemia (T-ALL) cells line BE-13, RPMI-8402 and DND-41, all three harboring a Notch1 mutation, and T-ALL primary cells from pediatric patients, with IC50 of 2-6 μM. 5 μM BMS-345541 induces an arrest in the G2/M phase of the cell cycle in BE-13 and DND-41 cells, and sub-G1 peak increase in RPMI-8402 cells. 5 μM BMS-345541 treated for 16 h leads to an increase in apoptotic cells in all these cell, accompanied by a time-dependent cleavage of procaspase-8, procaspase-3 and poly (ADP-ribose) polymerase (PARP). BMS-34554 (5 μM) induces a time dependent dephosphorylation of IκBα and p65. T-ALL cells treated with BMS-345541 displays nuclear translocation of FOXO3a and restoration of its functions, including control of p21^Cip1 expression levels. ^[4] BMS-345541 inhibits the TNFα-induced expression of both ICAM-1 and VCAM-1 in human umbilical vein endothelial cells with IC50 of 5 μM. ^[5]

BMS-345541 effectively inhibits melanoma tumor growth in a dose-dependent manner. Tumor-bearing mice treated with 75 mg/kg of BMS-345541 shows effective inhibition of growth of SK-MEL-5, A375, and Hs 294T tumors by 86 %, 69% and 67%, respectively, when compared with control animals treated with vehicle alone.[3]BMS-345541 administered orally at doses of 100 mg/kg, reduces the severity of dextran sulfate sodium-induced colitis in mice with weight ratio, clinical scoring of colons, mean injury score and mean inflammation score of 0.86 (vs 0.77 of vehicle group), 1.0 (vs 2.5 of vehicle group), 5.66 (vs 8.52 of vehicle group), 6.82 (vs 12.33 of vehicle group), respectively. ^[6] BMS-345541 (100 mg/kg), when administered by oral gavage in water once daily beginning at the time of the first collagen immunization, inhibits clinical signs of disease in the murine CIA model (0 vs ~8 of vehicle group), accompanied by reduced paw swelling. BMS-345541 (100 mg/kg) reduces cumulative arthritis injury score from 4.4 to 0, accompanied by lower degrade of tibiotarsal joints and severity of inflammation, synovial hyperplasia, bone resorption, and cartilage erosion. No discernible injury is observed in the joints of animals, which is histologically indistinguishable from those from age-matched, disease-free control animals. BMS-345541 dose-dependently inhibits IL-1β message, with animals in the 100 mg/kg dose group showing levels comparable with those of disease-free control animals. ^[7]