15-Biotinamino-4,7,10,13-tetraoxa-pentadecanoic acid succinimidyl ester (CAS# 459426-22-3) is a useful building block and has been featured in several screenings for anti-cancer activity. It has been used in the preparation of macrocyclic peptides for use as inhibitors of heat shock protein (Hsp90) in cancer cell lines.