Cimetidine is a histamine-2 (H2) receptor antagonist.IC50 Value: Target: Histamine-2 Receptorin vitro: Cimetidine, a partial agonist for H2R, has a pharmacological profile different from ranitidine and famotidine, possibly contributing to its antitumor activity on gastrointestinal cancers [1]. Cimetidine had no effect on the uptake and cytotoxicity of cisplatin in ovarian cancer cells with high OCT2 mRNA levels (IGROV-1 cells) [2]. Cimetidine showed no effect on proliferation, survival, migration and invasion of 3LL cells. Cimetidine reversed MDSC-mediated T-cell suppression, and improved IFN-γ production. [3]. Cimetidine-mediated down-regulation of NCAM involved suppression of the nuclear translocation of NF-kappaB, a transcriptional activator of NCAM gene expression [4].in vivo: the antitumor efficacy of cisplatin in mice bearing luciferase-tagged IGROV-1 xenografts was unaffected by cimetidine (P = 0.39). Data obtained in 18 patients receiving cisplatin (100 mg/m(2)) in a randomized crossover fashion with or without cimetidine (800 mg × 2) revealed that cimetidine did not alter exposure to unbound cisplatin [2]. cimetidine reduced CD11b(+)Gr-1(+) myeloid derived-suppressive cell (MDSC) accumulation in spleen, blood and tumor tissue of tumor-bearing mice [3]. Cimetidine exerts a beneficial effect on periodontal disease in rats, decreasing the RANKL/OPG ratio in gingival connective tissue and reducing alveolar bone resorption [5].

References:
[1]. Takahashi, H.K., et al., Cimetidine induces interleukin-18 production through H2-agonist activity in monocytes. Mol Pharmacol, 2006. 70(2): p. 450-3.
[2]. Sprowl, J.A., et al., Conjunctive therapy of cisplatin with the OCT2 inhibitor cimetidine: influence on antitumor efficacy and systemic clearance. Clin Pharmacol Ther, 2013. 94(5): p. 585-92.
[3]. Zheng, Y., et al., Cimetidine suppresses lung tumor growth in mice through proapoptosis of myeloid-derived suppressor cells. Mol Immunol, 2013. 54(1): p. 74-83.
[4]. Fukuda, M., K. Kusama, and H. Sakashita, Cimetidine inhibits salivary gland tumor cell adhesion to neural cells and induces apoptosis by blocking NCAM expression. BMC Cancer, 2008. 8: p. 376.
[5]. Longhini, R., et al., Cimetidine Reduces the Alveolar Bone Loss in Induced Periodontitis in Rat Molars. J Periodontol, 2013.