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Vapreotide attenuates the Substance P (SP)-triggered intracellular calcium increases and NF-κB activation in a dose-dependent manner. Vapreotide also inhibits SP-induced IL-8 and MCP-1 production in HEK293-NK1R and U373MG cell lines. Vapreotide inhibits HIV-1 infection of human MDM in vitro , an effect that is reversible by SP pretreatment. Vapreotide significantly inhibits GH-, PRL, and/or alpha-subunit release by human GH-secreting pituitary adenoma cells in concentrations as low as 10 ^-12 -10 ^-14 M. Vapreotide inhibits GH release with an IC ₅₀ of 0.1 pM. Vapreotide exhibits moderate-to-high affinities for SSTR2, -3, and -5 (IC ₅₀ =0.17, 0.1 and 21 nM, respectively) and low affinity for SSTR1 and -4 (IC ₅₀ =200 and 620 nM, respectively). RC-160 inhibits serum-induced proliferation of CHO cells expressing SSTR2 and SSTR5 (EC ₅₀ =53 and 150 pM, respectively).

In cirrhosis, bleeding by rupture of oesophagogastric varices is a severe complication of portal hypertension. The acute administration of vapreotide to rats decreases collateral circulation blood flow while chronic administration attenuated its development. Tumor volumes and weights are reduced by about 40% by RC-160 by s.c. injections at doses of 100 μg/day/animal. Vapreotide can inhibit the growth of androgen-independent prostate cancer when the therapy is started at an early stage of tumor development.