Substance P analog that is a broad spectrum neuropeptide antagonist and antiproliferative agent. Blocks Swiss 3T3 cell growth induced by vasopressin, gastrin-releasing peptide and bradykinin. Inhibits neuropeptide-dependent and -independent proliferation of small cell lung cancer in vitro; activates JNK and stimulates apoptosis. Inhibits growth of SCLC xenografts in mice in vivo. MW (observed): 951.2.