IRL-1620 significantly enhanced delivery and effectiveness of paclitaxel in an animal model of breast cancer. IRL-1620 together with IRL-1038 (Prod. No. ALX-155-007) is an indispensable pharmacological tool to assess the participation of the ETB receptor in some pathophysiological phenomena, by selectively stimulating ETB receptor-mediated responses in various pathophysiological models established in vitro and in vivo.