Heat shock protein 90 (HSP90) improve the stability and activity of many signaling proteins that promote cancer cell growth and/or survival (1, 2). HSP90 inhibitors (HSP90i) such as geldamanycin (GM), AUY922 and STA-9090 have been developed for blockage of multiple signaling pathways that are initiated by HSP90 (3).

To enhance anticancer efficacy of HSP90i, HER2 targeted HSP90i delivery system (HER2-HBD) was constructed and expressed from 293 cells. This system could incorporate HSP90i into recombinant antibody fusion protein based on biological binding affinity. HER2-HBD and HSP90i was spontaneously formed HER2-HBD/HSP90i complex. HER2-HBD/HSP90i complex delivered HSP90i into HER2 positive cancer cell and decreased cancer cell growth in vitro and in vivo test.

HER2-HBD recombinant system based on biological affinity between HSP90i and HBD was not required chemical reaction to conjugate antibody and drug. This system might be useful targeted delivery systems for HSP90i without tailored conjugation method to develop antibody-drug conjugate (ADC).