PURPOSE: Targeting Hsp90 has significant potential as a treatment for prostate cancer, but prototypical agents such as 17-allylamino-17 demethoxygeldanamycin (17-AAG) have been ineffective in clinical trials.
Recently, a phase I study aimed at defining a biologically active dose reported the first response to an Hsp90 inhibitor in a patient with prostate cancer, which supports the development of new generation compounds for this disease.
EXPERIMENTAL DESIGN: The biological actions of two new synthetic Hsp90 inhibitors, NVP-AUY922 and NVP-HSP990, were evaluated in the prostate cancer cell lines PC-3, LNCaP, and VCaP and in an ex vivo culture model of human prostate cancer.
RESULTS: In cell lines, both NVP-AUY922 and NVP-HSP990 showed greater potency than 17-AAG with regard to modulation of Hsp90 client proteins, inhibition of proliferation, and induction of apoptotic cell death. In prostate tumors obtained from radical prostatectomy that were cultured ex vivo, treatment with 500 nmol/L of NVP-AUY922, NVP-HSP990, or 17-AAG caused equivalent target modulation, determined by the pharmacodynamic marker Hsp70, but only NVP-AUY922 and NVP-HSP990 showed antiproliferative and proapoptotic activity.
CONCLUSIONS: This study provides some of the first evidence that new generation Hsp90 inhibitors are capable of achieving biologic responses in human prostate tumors, with both NVP-AUY922 and NVP-HSP990 showing potent on-target efficacy. Importantly, the ex vivo culture technique has provided information on Hsp90 inhibitor action not previously observed in cell lines or animal models. This approach, therefore, has the potential to enable more rational selection of therapeutic agents and biomarkers of response for clinical trials.
Written by:
Centenera MM, Gillis JL, Hanson AR, Jindal S, Taylor RA, Risbridger GP, Sutherland PD, Scher HI, Raj GV, Knudsen KE, Yeadon T, Tilley WD, Butler LM. Are you the author?
Dame Roma Mitchell Cancer Research Laboratories and Adelaide Prostate Cancer Research Centre, University of Adelaide and Hanson Institute, Adelaide; Urology Unit, Surgical Specialties Service, Royal Adelaide Hospital, Adelaide; Prostate and Breast Cancer Research Group, Department of Anatomy and Developmental Biology, Monash University, Clayton, Australia; Genitourinary Oncology Service, Memorial Sloan-Kettering Cancer Center, New York; Department of Urology, UT Southwestern Medical Center at Dallas, Dallas, Texas; and Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania.
Reference: Clin Cancer Res. 2012 Jul 1;18(13):3562-3570.
doi: 10.1158/1078-0432.CCR-12-0782
PubMed Abstract
PMID: 22573351
UroToday.com Investigative Urology Section