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)

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 osimertinibresistant 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.

Establishment of Acquired Cisplatin Resistance in Ovarian Cancer Cell Lines Characterized by Enriched Metastatic Properties with Increased Twist Expression

“…In ovarian cancer research, in vitro cell line models become effective tools to understand the molecular mechanisms underlying acquired chemo-resistance development in ovarian cancer [ 59 , 60 , 61 , 62 ]. We derived and confirmed the acquired cisplatin resistance cell model through both pulse and stepwise dose increasing methods, which offer a useful tool for describing the molecular mechanisms of acquired cisplatin resistance.…”

Histone Deacetylase Inhibition in Non-small Cell Lung Cancer: Hype or Hope?

“…Although median PFS was 5.2 months, median OS on this small early phase trial was encouraging at 22.1 months. Similarly, combination of HDACi panobinostat with third generation EGFR TKI osimertinib has been shown to enhance the induction of apoptosis and decrease the survival of osimertinib resistant cell lines and xenograft models, including those harboring C797S mutations, via elevation of BIM ( Zang et al, 2020 ).…”

Cell Line Models for Acquired Resistance to First-Line Osimertinib in Lung Cancers—Applications and Limitations

“…Our search criteria included the following terms: “osimertinib,” “resistance,” “lung cancer,” and “cell line” or “cell lines.” We also manually scanned the reference lists of selected articles for additional eligible publications. We finally identified 29 relevant papers [ 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 ]. We excluded 2 of these papers [ 47 , 49 ], as they used osimertinib-resistant cell lines that had been established in other studies included in our survey.…”

“…The authors showed that MEK inhibitors (GSK1120212 or PD-0325901) combined with osimertinib reduced MCL-1 expression and could overcome the resistance [ 34 ]. The same group reported in a later study that honokiol (a natural product isolated from the bark, seed cones, and leaves of trees belonging to the genus Magnolia ) plus osimertinib enhanced MCL-1 reduction by suppressing ERK-dependent MCL-1 phosphorylation [ 47 ], and that the histone deacetylase inhibitor (LBH589) enhanced the effects of osimertinib in the resistant cells by decreasing levels of p-ERK and increasing BIM levels [ 49 ]. Another group reported that in experiments using PC9 and H1975 cells, BIM downregulation was the mechanism of AR to osimertinib.…”

“…We finally identified 29 relevant papers . We excluded 2 of these papers [47,49], as they used osimertinib-resistant cell lines that had been established in other studies included in our survey.…”