The present invention relates to a method for suppressing neuroendocrine disease. The therapy employs use of a non-cytotoxic protease, which is targeted to a neuroendocrine tumour cell, preferably via a somatostatin or cortistatin receptor, a GHRH receptor, a ghrelin receptor, a bombesin receptor, a urotensin receptor a melanin-concentrating hormone receptor 1; a KiSS-1 receptor or a prolactin-releasing peptide receptor. When so delivered, the protease is internalised and inhibits secretion from said tumour cell. The present invention also relates to polypeptides and nucleic acids for use in said methods.