Ralimetinib (LY2228820) dimesylate

2 years -80 in solvent

Oral bid dosing for 14 days

MM cells, including INA6, RPMI-8226, U266, and RPMI-Dox40

200 nM–800 nM

Dissolved in 1% CMC/0.25% Tween 80 in water

LY2228820 inhibits p38alpha, as well as the level of phosphoMAPKAPK-2 (pMK2) in RAW 264.7 cells, with IC50 values of 7 nM and 34.3 nM, respectively. Furthermore, LY2228820 inhibits lipopolysaccharide (LPS)-induced TNFalpha formation in murine peritoneal macrophages, with IC50 of 5.2 nM. [1] In multiple myeloma (MM) cells, including INA6, RPMI-8226, U266, and RPMI-Dox40, LY2228820 (200 nM–800 nM) significantly blocks p38MAPK signaling, as revealed by its inhibition on phosphorylation of HSP27, a downstream target of p38MAPK, without affecting the expression level of HSP27. LY2228820 (200 nM–400 nM) enhances bortezomib-induced cytotoxicity and apoptosis, but LY2228820 alone doesn't inhibit the growth of MM.1S cells. LY2228820 (200 nM–800 nM) also inhibits secretion of IL-6 and MIP-1alpha in long-term BM stromal cells (LT-BMSCs), BM mononuclear cells (BMMNCs), peripheral blood (PB) CD138+, CD138 or PB CD14+ cells. LY2228820 (400 nM–800 nM) also blocks osteoclastogenesis from CD14+ cells. [2]

48 hours

MTT assays and APO 2.7 staining are performed to assess cellular proliferation and induction of apoptosis, respectively. Viability is expressed as percent viable cells. Apoptosis in cells is evaluated by APO 2.7 staining. For detection of mitochondrial membrane protein 7A6 expressed in apoptotic cells, cells are incubated with APO 2.7 reagent for 20 min. Expression of APO 2.7 is determined using an EPICS XL flow cytometer.

Ralimetinib (LY2228820) dimesylate is a novel and potent inhibitor of p38 MAPK with IC50 of 7 nM in a cell-free assay, does not alter p38 MAPK activation. Phase 1/2.