IPI-504 is a novel, water-soluble analog of 17-AAG and a potent inhibitor of Hsp90. Hsp90's role in the cell is to control the proper folding, function, and viability of various "client" proteins. Many of these client proteins (such as AKT, Her-2, Bcr-Abl, PDGFR-α, and c-Kit) are oncoproteins or important cell signaling proteins. Inhibition of HSP-90 leads to the proteasomal degradation of these proteins.
In patients with HRPC,there are several proteins that are important in the progression of HRPC, including AR, AKT and Her-2. All of these are client proteins of Hsp90 and in response to Hsp90 inhibition are degraded by their proteasome. Preclinical studies have shown that Hsp90 inhibition causes a dose dependent degradation of these client proteins and growth inhibition of prostate cancer in xenograft tumors.
