A human monoclonal antibody targeting the stem cell factor receptor (c-Kit) blocks tumor cell signaling and inhibits tumor growth

作者：Lebron Maria B; Brennan Laura; Damoci Christopher B; Prewett Marie C; O'Mahony Marguerita; Duignan Inga J; Credille Kelly M; DeLigio James T; Starodubtseva Marina; Amatulli Michael; Zhang Yiwei; Schwartz Kaben D; Burtrum Douglas; Balderes Paul; Persaud Kris; Surguladze David; Loizos Nick; Paz Keren; Kotanides Helen^*

来源：Cancer Biology and Therapy, 2014, 15(9): 1208-1218.

DOI：10.4161/cbt.29523

• c-Kit
• monoclonal antibody
• tumor cell signaling
• tumor growth
• targeted therapy

Stem cell factor receptor (c-Kit) exerts multiple biological effects on target cells upon binding its ligand stem cell factor (SCF). Aberrant activation of c-Kit results in dysregulated signaling and is implicated in the pathogenesis of numerous cancers. The development of more specific and effective c-Kit therapies is warranted given its essential role in tumorigenesis. In this study, we describe the biological properties of CK6, a fully human IgG1 monoclonal antibody against the extracellular region of human c-Kit. CK6 specifically binds c-Kit receptor with high affinity (EC50 = 0.06 nM) and strongly blocks its interaction with SCF (IC50 = 0.41 nM) in solid phase assays. Flow cytometry shows CK6 binding to c-Kit on the cell surface of human small cell lung carcinoma (SCLC), melanoma, and leukemia tumor cell lines. Furthermore, exposure to CK6 inhibits SCF stimulation of c-Kit tyrosine kinase activity and downstream signaling pathways such as mitogen-activated protein kinase (MAPK) and protein kinase B (AKT), in addition to reducing tumor cell line growth in vitro. CK6 treatment significantly decreases human xenograft tumor growth in NCI-H526 SCLC (T/C% = 57) and Malme-3M melanoma (T/C% = 58) models in vivo. The combination of CK6 with standard of care chemotherapy agents, cisplatin and etoposide for SCLC or dacarbazine for melanoma, more potently reduces tumor growth (SCLC T/C% = 24, melanoma T/C% = 38) compared with CK6 or chemotherapy alone. In summary, our results demonstrate that CK6 is a c-Kit antagonist antibody with tumor growth neutralizing properties and are highly suggestive of potential therapeutic application in treating human malignancies harboring c-Kit receptor.

• 出版日期2014