Focal Adhesion Kinase Inhibitors in Combination with Erlotinib Demonstrate Enhanced Anti-Tumor Activity in Non-Small Cell Lung Cancer

Abstract

Blockade of epidermal growth factor receptor (EGFR) activity has been a primary therapeutic target for non-small cell lung cancers (NSCLC). As patients with wild-type EGFR have demonstrated only modest benefit from EGFR tyrosine kinase inhibitors (TKIs), there is a need for additional therapeutic approaches in patients with wild-type EGFR. As a key component of downstream integrin signalling and known receptor cross-talk with EGFR, we hypothesized that targeting focal adhesion kinase (FAK) activity, which has also been shown to correlate with aggressive stage in NSCLC, would lead to enhanced activity of EGFR TKIs. As such, EGFR TKI-resistant NSCLC cells (A549, H1299, H1975) were treated with the EGFR TKI erlotinib and FAK inhibitors (PF-573,228 or PF-562,271) both as single agents and in combination. We determined cell viability, apoptosis and 3-dimensional growth in vitro and assessed tumor growth in vivo. Treatment of EGFR TKI-resistant NSCLC cells with FAK inhibitor alone effectively inhibited cell viability in all cell lines tested; however, its use in combination with the EGFR TKI erlotinib was more effective at reducing cell viability than either treatment alone when tested in both 2- and 3-dimensional assays in vitro, with enhanced benefit seen in A549 cells. This increased efficacy may be due in part to the observed inhibition of Akt phosphorylation when the drugs were used in combination, where again A549 cells demonstrated the most inhibition following treatment with the drug combination. Combining erlotinib with FAK inhibitor was also potent in vivo as evidenced by reduced tumor growth in the A549 mouse xenograft model. We further ascertained that the enhanced sensitivity was irrespective of the LKB1 mutational status. In summary, we demonstrate the effectiveness of combining erlotinib and FAK inhibitors for use in known EGFR wild-type, EGFR TKI resistant cells, with the potential that a subset of cell types, which includes A549, could be particularly sensitive to this combination treatment. As such, further evaluation of this combination therapy is warranted and could prove to be an effective therapeutic approach for patients with inherent EGFR TKI-resistant NSCLC.

MicroRNA-433 inhibits oral squamous cell carcinoma cells by targeting FAK

“…FAK has been verified as the target gene for several other miRs (miR-543 and miR-7) in cancer development [ 17 , 31 ]. FAK overexpression in OSCC cells has been associated with histological differentiation, lymphatic metastasis, TNM stage, and is an independent prognostic factor [ 32 ]. A previous study demonstrated that knockdown of FAK in carcinoma-associated fibroblasts (CAFs) might suppress OSCC metastasis, and suggested that targeting FAK in CAFs may be a promising strategy for the OSCC treatment [ 33 ].…”

Role of Integrins in Resistance to Therapies Targeting Growth Factor Receptors in Cancer

“…Integrin-dependent FAK activation decreased cancer cells’ sensitivity to anti-EGFR drugs [10,14]. A series of studies confirmed the importance of FAK signaling in resistance to first- (erlotinib), second- (afatinib) and third-generation (osimertinib) EGFR TKIs [28,29,30,31].…”

Targeting focal adhesion kinase overcomes erlotinib resistance in smoke induced lung cancer by altering phosphorylation of epidermal growth factor receptor

“…Having observed that the inhibition of SRC/FAK signaling in H358-S and other NSCLC cells leads to decreased invasive ability, we sought to study the effects of these inhibitors on erlotinib sensitivity of smoke-exposed cells. In a recent study, combinatorial treatment of FAK inhibitor and erlotinib have shown synergistic effect in reducing cell viability in EGFR-TKI-resistant NSCLC cell lines [ 48 ]. H358-S, H1299 and H1650 cells were treated with varying concentration of erlotinib (0.5 µM, 1 µM and 3 µM) alone or in combination with either SRC inhibitor, dasatanib (50 nM) or FAK inhibitor, PF-562271 (4 µM) (Figure 5A-D ).…”

“…Emerging studies have shown FAK as potential cancer target in multiple cancer types [ 69 - 71 ] and phase I/II clinical trial outcomes of FAK inhibitors are awaited [ 72 ]. A recent study reported higher efficacy and synergistic effects of FAK inhibitor when used in combination with erlotinib using in-vitro and in-vivo experiments [ 48 ]. The SRC-3Delta4, a SRC3 splicing isoform is known to mediate the interaction of FAK with EGFR in mammals [ 73 ].…”