Abstract: Geldanamycin derivatives that block the uPA-plasmin network and inhibit growth and invasion by glioblastoma cells and other tumors at femtomolar concentrations are potentially highly active anti-cancer drugs. GA and various 17-amino-17-demethoxygelddanamycin derivatives are disclosed that block HGF/SF-mediated Met tyrosine kinase receptor-dependent uPA activation at fM levels. Other ansamycins (macbecins I and II), GA derivatives, and radicicol required concentrations several logs higher (?nM) to achieve such inhibition. The inhibitory activity of tested compounds was discordant with the known ability of drugs of this class to bind to hsp90, indicating the existence of a novel target(s) for HGF/SF-mediated events in tumor development. Methods of using such compounds to inhibit cancer cell activities and to treat tumors are disclosed.

Abstract: The present invention relates to novel geldanamycin derivatives which have antitumor and antiparasitic properties. The geldanamycin derivatives disclosed herein have antitumor properties in humans due to their interaction with human heat shock protein 90 (hsp90). The human parasites Plasmodium falciparum, Trypanosoma Cruzi, and Leishmania donovani are lethally susceptible to exposure to geldanamycin via complexation of geldanamycin with their homologs (Pfhsp90, hsp83, and hsp90, respectively) of the human hsp90. The geldanamycin derivatives disclosed herein also interact with these parasitic hsp90 homologs so as to have antiparasitic properties.