Activation of vagus nerve by semapimod alters substance P levels and decreases breast cancer metastasis

► Semapimod decreased lung and liver metastases in control animals but not in vagotomized animals. ► Semapimod increased substance P (SP) levels in capsaicin sensitive nerve endings. ► The effects of semapimod on SP levels were prevented by vagotomy. ► Semapimod increased neprilysin-like activity in lung tissue of control animals.