Heat shock protein 90 inhibitors in non-small-cell lung cancer

Heat shock protein 90 (Hsp90) protects cellular proteins from degradation by the ubiquitin-proteasome system in conditions of stress. Many cancers have increased expression of Hsp90 to ensure their malignant phenotype of increased proliferation, decreased apoptosis, and metastatic potential by conservation of proteins like epidermal growth factor receptor (EGFR), human epidermal growth factor receptor 2, anaplastic lymphoma kinase (ALK), v-Raf murine sarcoma viral oncogene homologue B1, AKT, B-cell lymphoma 2, and cell cycle proteins. This review discusses recent developments in the strategy of Hsp90 inhibition as a targeted therapy in non-small-cell lung cancer (NSCLC).

Hsp90 inhibitors result in growth inhibition and tumor regression in NSCLC cell lines and tumor xenograft models, both as monotherapy and in combination with other drugs. Hsp90 inhibition has particular efficacy in molecular subtypes of NSCLC, such as EGFR-mutated and ALK-rearranged NSCLC. IPI-504 and ganetespib have activity in NSCLC both as monotherapy and in combination with docetaxel.

Preclinical studies and early clinical trials have confirmed the efficacy of Hsp90 inhibition as a targeted therapy in NSCLC. Ongoing trials will further define the utility of Hsp90 inhibitors in NSCLC.