We describe the
biological properties of
NVP-AUY922, a novel resorcinylic
isoxazole amide heat shock protein 90 (HSP90) inhibitor.
NVP-AUY922 potently inhibits HSP90 (K(d) = 1.7 nmol/L) and proliferation of human
tumor cells with GI(50) values of approximately 2 to 40 nmol/L, inducing G(1)-G(2) arrest and apoptosis. Activity is independent of NQO1/
DT-diaphorase, maintained in
drug-resistant cells and under hypoxic conditions. The molecular signature of HSP90 inhibition, comprising induced HSP72 and depleted client
proteins, was readily demonstrable.
NVP-AUY922 was glucuronidated less than previously described
isoxazoles, yielding higher
drug levels in human
cancer cells and xenografts. Daily dosing of
NVP-AUY922 (50 mg/kg i.p. or i.v.) to athymic mice generated peak
tumor levels at least 100-fold above cellular GI(50). This produced statistically significant growth inhibition and/or regressions in human
tumor xenografts with diverse oncogenic profiles: BT474
breast tumor treated/control, 21%; A2780 ovarian, 11%; U87MG
glioblastoma, 7%; PC3 prostate, 37%; and WM266.4
melanoma, 31%.
Therapeutic effects were concordant with changes in pharmacodynamic markers, including induction of HSP72 and depletion of ERBB2, CRAF,
cyclin-dependent kinase 4, phospho-AKT/total AKT, and
hypoxia-inducible factor-1alpha, determined by Western blot, electrochemiluminescent immunoassay, or immunohistochemistry.
NVP-AUY922 also significantly inhibited
tumor cell chemotaxis/invasion in vitro, WM266.4
melanoma lung
metastases, and
lymphatic metastases from orthotopically implanted PC3LN3 prostate
carcinoma.
NVP-AUY922 inhibited proliferation, chemomigration, and tubular differentiation of human endothelial cells and antiangiogenic activity was reflected in reduced microvessel density in
tumor xenografts. Collectively, the data show that
NVP-AUY922 is a potent, novel inhibitor of HSP90, acting via several processes (cytostasis, apoptosis, invasion, and angiogenesis) to inhibit
tumor growth and
metastasis.
NVP-AUY922 has entered phase I clinical trials.