The FGFR1 V561M Gatekeeper Mutation Drives AZD4547 Resistance through STAT3 Activation and EMT

Abstract

FGFR1 has been implicated in numerous cancer types including squamous cell lung cancer, a subset of non-small cell lung cancer with a dismal 5-year survival rate. Smallmolecule inhibitors targeting FGFR1 are currently in clinical trials, with AZD4547 being one of the furthest along; however, the development of drug resistance is a major challenge for targeted therapies. A prevalent mechanism of drug resistance in kinases occurs through mutation of the gatekeeper residue, V561M in FGFR1; however, mechanisms underlying V561M resistance to AZD4547 are not fully understood. Here, the cellular consequences of the V561M gatekeeper mutation were characterized, and it was found that although AZD4547 maintains nanomolar affinity for V561M FGFR1, based on in vitro binding assays, cells expressing V561M demonstrate dramatic resistance to AZD4547 driven by increased STAT3 activation downstream of V561M FGFR1. The data reveal that the V561M mutation biases cells toward a more mesenchymal phenotype, including increased levels of proliferation, migration, invasion, and anchorage-independent growth, which was confirmed using CyTOF, a novel single-cell analysis tool. Using shRNA knockdown, loss of STAT3 restored sensitivity of cancer cells expressing V561M FGFR1 to AZD4547. Thus, the data demonstrate that combination therapies including FGFR and STAT3 may overcome V561M FGFR1-driven drug resistance in the clinic.Implications: The V561M FGFR1 gatekeeper mutation leads to devastating drug resistance through activation of STAT3 and the epithelial-mesenchymal transition; this study demonstrates that FGFR1 inhibitor sensitivity can be restored upon STAT3 knockdown.

Fibroblast Growth Factor Receptors (FGFRs): Structures and Small Molecule Inhibitors

“…One common mechanism of resistance is generated by mutating the so-called gatekeeper residue of the kinase domain [101]. The gatekeeper mutation has been reported in various kinases, such as Bcr-Abl (T315I) [102], EGFR (T790M) [68], PDGFR (T674I) [103], FGFR1 (V561M) [104] and FGFR2 (V565I) [105]. The gatekeeper residue lies at the beginning of the hinge region and controls the accessibility of the hydrophobic pocket.…”

FGFR1 regulates proliferation and metastasis by targeting CCND1 in FGFR1 amplified lung cancer

“…As mentioned above, FGFR1 as an attractive target demonstrated modest response [42]. Therefore, signaling paradigm co-alternation with FGFR1 or genes have been widely studied, such as the co-active receptor tyrosine kinases, the co-activation of MTOR pathway, et al [15,19,43,44]. We demonstrated the co-expression of FGFR1 and CCND1 in lung cancer.…”

“…BGJ398 and AZD4547 are selective inhibitors of FGFR 1-3 in phase Ib clinical trials [15,16]. However, the efficacy of these inhibitors are modest [17][18][19].…”

mRNA Expression of FGFR1 as Potential Marker for Predicting Prognosis of Surgical Resection of Small Cell Lung Cancer may be better than Protein Expression and Gene Amplification

“…The latest study from a phaseⅠclinical trial suggested that rogaratinib, a novel kinase inhibitor of FGFR1-4, resulted in an encouraging antitumor activity, if screened by FGFR mRNA overexpressing cancers [11]. In addition, the mutation in FGFR1 V561M gatekeeper drives the FGFR TKI AZD4547 resistance in vitro [12]. However, very few or none studies examined FGFR1 mRNA expression and mutation with tissue samples from patients and assessed their values.…”