PF-04929113 is a prodrug for the Hsp90 inhibitor, PF-04958473 (SNX-2112), which binds both Hsp90α and Hsp90β with an IC50 value of 30 nM. The prodrug, PF-04929113, is rapidly absorbed and converted into the active inhibitor after oral administration. The active inhibitor causes degradation of Hsp90 client proteins, including HER2, and reduces phosphorylation of downstream kinases, including Akt and ERK1/2, leading to apoptosis in cancer cells. Oral administration of the prodrug, PF-04929113, reduces tumor growth and prolongs survival in mouse models of multiple myeloma and prostate cancer.
