Overcoming acquired resistance of epidermal growth factor receptor-mutant non-small-cell lung cancer cells to osimertinib by combining osimertinib with the histone deacetylase inhibitor panobinostat (LBH589)

• Type of Material: Article
• Authors: Hongjing Zang, Emory University; Guoqing Qian, Emory University; Dan Zong, Emory University; Songqing Fan, Central South University; Taofeek Owonikoko, Emory University; Suresh Ramalingam, Emory University; Shi-Yong Sun, Emory University
• Language: English
• Date: 2020-01-30
• Publisher: Wiley
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2020 American Cancer Society
• Final Published Version (URL): http://dx.doi.org/10.1002/cncr.32744
• Title of Journal or Parent Work: Cancer
• Volume: 126
• Issue: 9
• Start Page: 2024
• End Page: 2033
• Grant/Funding Information: Lee Foundation Award to the Winship Lung Cancer Program for supporting the pilot project (to SSR and SYS).; This study was supported in part by NIH/NCI R01 CA223220 (to SYS) and UG1 CA233259 (to SSR and SYS); Emory University Winship Cancer Institute lung cancer pilot fund (to S-Y. S.)
• Keywords: Activation; Phosphorylation; Science & Technology; LBH589; BH3-only protein; Combination; Life Sciences & Biomedicine; epidermal growth factor receptor (EGFR); Oncology; histone deacetylase (HDAC); Polymorphism; apoptosis; EGFR TKIS; lung cancer; Degradation; Expression; acquired resistance; BIM; osimertinib; HDAC inhibitor
• Research Categories: Biology, Cell; Health Sciences, Immunology; Health Sciences, Oncology; Health Sciences, Pathology

Abstract

Background: The major clinical obstacle that limits the long-term benefits of treatment with osimertinib (AZD9291) in patients with epidermal growth factor receptor-mutant non–small cell lung cancer is the development of acquired resistance. Therefore, effective strategies that can overcome acquired resistance to osimertinib are urgently needed. The authors' current efforts in this direction have identified LBH589 (panobinostat), a clinically used histone deacetylase inhibitor, as a potential agent in overcoming osimertinib resistance. Methods: Cell growth and apoptosis in vitro were evaluated by measuring cell numbers and colony formation and by detecting annexin V-positive cells and protein cleavage, respectively. Drug effects on tumor growth in vivo were assessed with xenografts in nude mice. Alterations of tested proteins in cells were monitored with Western blot analysis. Gene knockout was achieved using the CRISPR/Cas9 technique. Results: The combination of LBH589 and osimertinib synergistically decreased the survival of different osimertinib-resistant cell lines, including those harboring C797S mutations, with greater inhibition of cell colony formation and growth. The combination enhanced the induction of apoptosis in osimertinib-resistant cells. Importantly, the combination effectively inhibited the growth of osimertinib-resistant xenograft tumors in nude mice. Mechanistically, the combination of LBH589 and osimertinib enhanced the elevation of Bim in osimertinib-resistant cells. Knockout of Bim in osimertinib-resistant cells substantially attenuated or abolished apoptosis enhanced by the LBH589 and osimertinib combination. These results collectively support a critical role of Bim elevation in the induction of apoptosis of osimertinib-resistant cells for this combination. Conclusions: The current findings provide strong preclinical evidence in support of the potential for LBH589 to overcome osimertinib resistance in the clinic.