AT2 Receptor Stimulation May Halt Progression of Pheochromocytoma

Two patients with pheochromocytoma are described in whom treatment with a high dose of an angiotensin receptor blocker was associated with cessation of tumor growth as assessed by serial CT scanning and plasma norepinephrine estimation. If the association with drug treatment is causal, the mechanism may be through stimulation of the AT2 receptor consequent upon the elevation of plasma angiotensin II levels induced by AT1 receptor blockade. Similar observations in further patients should lead to a placebo-controlled study in patients with malignant or familial pheochromocytoma, or other tumors found to express the AT2 receptor.