p38 alpha -Selective MAP Kinase Inhibitor Reduces Tumor Growth in Mouse Xenograft Models of Multiple Myeloma

• Published in: Anticancer research 2008-11, Vol.28 (6A), p.3827-3834
• Main Authors: Medicherla, S, Reddy, M, Ma, J Y, Navas, T A, Li, L, Nguyen, AN, Kerr, I, Hanjarappa, N, Protter, A A, Higgins, L S
• Format: Article
• Language: English
• ISSN: 0250-7005

Multiple myeloma (MM) is a clonal plasma cell malignancy, which is currently incurable. Therefore, new mono- or combined therapy treatment regimens in the early and advanced phases of MM are urgently needed to combat this disease. Recently, p38 mitogen-activated protein kinase (MAPK) has been implicated as playing an important role in MM. Therefore, the effect of a p38 alpha -selective MAPK inhibitor, SCIO-469 (indole-5-carboxamide, ATP-competitive inhibitor), or its structural analog, SD-282 (indole-5-carboxamide, ATP-competitive inhibitor) was examined in mouse xenograft models of MM using human RPMI-8226 or H-929 plasmacytoma inocula. Oral treatment with SCIO-469 (10, 30, 90 mg/kg) twice daily was initiated in mice with palpable tumors of RPMI-8226 origin, a condition that mimics early human myeloma disease. In mice with palpable tumors, 14 days of SCIO-469 treatment significantly reduced RPMI-8226 tumor growth in a dose-dependent manner. A significant dose-dependent reduction in RPMI-8226 tumor growth was also observed when SCIO-469 oral treatment at doses of 10, 30 and 90 mg/kg twice daily was initiated in mice with tumors of pronounced size, a condition that mimics advanced human myeloma disease. In a similar set of studies employing the SCIO-469 analogue SD-282 at 90 mg/kg/bid orally, histological assessment at the end of the study demonstrated a significant reduction in RPMI-8226 tumor growth and angiogenesis. SD-282 treatment was additionally shown to significantly reduced expression of heat-shock protein-27 (HSP-27) and phospho-p38 in the tumor cells. Furthermore, co-administration of SCIO-469 with dexamethasone elicited antitumor properties in dexamethasone-sensitive H-929 tumors at much lower than the typically effective doses of dexamethasone, suggesting its potential for combined therapy.