Luminespib (NVP-AUY922) is a highly potent isoxazole-based, nongeldanamycin HSP90 inhibitor that inhibits the adenosine triphosphatase activity of HSP90. Luminespib is a highly potent HSP90 inhibitor for HSP90α/β with IC50 of 13 nM /21 nM in cell-free assays, weaker potency against the HSP90 family members GRP94 and TRAP-1, exhibits the tightest binding of any small-molecule HSP90 ligand. Luminespib potently inhibited in vitro growth in all 41 NSCLC cell lines evaluated with IC50 less than 100 nM. IC100 value less than 40 nM was seen in 36 of 41 lines. Luminespib (NVP-AUY922) has greater potency, reduced hepatotoxicity, and lower dependence on DT-diaphorase than the first-generation HSP90 inhibitors. Luminespib was discovered in a multiparameter lead optimization program based on a high-throughput screening hit methodology developed jointly by The Institute of Cancer Research, UK and the pharmaceutical company Vernalis. It has been licensed to Novartis. Luminespib 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. Pre-clinical studies proved that Luminespib acts via several processes (cytostasis, apoptosis, invasion, and angiogenesis) to inhibit tumor growth and metastasis. These results helped Luminespib to enter clinical trials for various cancers including breast cancers. From 2011 to 2014 it was in Phase II clinical trials.