Transcriptomics and Transposon Mutagenesis Identify Multiple Mechanisms of Resistance to the FGFR Inhibitor AZD4547

Abstract

In human cancers, FGFR signaling is frequently hyperactivated by deregulation of FGF ligands or by activating mutations in the FGFR receptors such as gene amplifications, point mutations, and gene fusions. As such, FGFR inhibitors are considered an attractive therapeutic strategy for patients with mutations in FGFR family members. We previously identified as a key driver of invasive lobular carcinoma (ILC) in an insertional mutagenesis screen using the transposon system. Here we explore whether these FGFR-driven ILCs are sensitive to the FGFR inhibitor AZD4547 and use transposon mutagenesis in these tumors to identify potential mechanisms of resistance to therapy. Combined with RNA sequencing-based analyses of AZD4547-resistant tumors, our approach identified several known and novel potential resistance mechanisms to FGFR inhibition, most of which converged on reactivation of the canonical MAPK-ERK signaling cascade. Observed resistance mechanisms included mutations in the tyrosine kinase domain of FGFR2, overexpression of MET, inactivation of RASA1, and activation of the drug-efflux transporter ABCG2. ABCG2 and RASA1 were identified only from transposon insertions acquired during AZD4547 treatment, demonstrating that insertional mutagenesis in mice is an effective tool for identifying potential mechanisms of resistance to targeted cancer therapies. These findings demonstrate that a combined approach of transcriptomics and insertional mutagenesis is an effective method for identifying potential targets to overcome resistance to therapy in the clinic. .

Futibatinib Is a Novel Irreversible FGFR 1–4 Inhibitor That Shows Selective Antitumor Activity against FGFR-Deregulated Tumors

“…(23). Similarly, AZD4547 has been shown to be susceptible to acquired resistance (46). Data on acquired resistance with the newer inhibitors erdafitinib and pemigatinib (which have shown efficacy in patients with advanced cancers [17,20]) have yet to be reported.…”

Src-dependent DBL family members drive resistance to vemurafenib in human melanoma

“…proliferation, drug treatment), cells with specific mutations conferring the ability to outcompete neighboring cells undergo clonal expansion, facilitating subsequent identification of these phenotype-driving mutations. This method has been used to select for specific phenotypes using ex vivo cell-based assays (15-17), as well as to drive the development of drug-resistant tumors in a engineered mouse models (18,19). However, previous ex vivo approaches using human cells have been limited by the relative inefficiency of delivering both transposon and transposase vectors to cells.…”

Role of RASA1 in cancer: A review and update (Review)

“…A previous study has revealed that FGFR-2 mutation is an important driver of lung cancer, which has become a key target of lung cancer drug development. In an FGFR2-mutant resistant model, RASA1 was found to be inactivated ( 66 ).…”

“…The activated Raf kinase continues to phosphorylate and activate MAPKK protein kinase MEK1/2 and finally phosphorylates and activates ERK1/2, inducing abnormal proliferation, invasion, growth, and distant metastasis of malignant tumours ( 75 , 123 ). In addition, loss of RASA1 function can enhance RAS-ERK signal amplification ( 66 , 78 ). PI3K/AKT have been described as key regulators of cell proliferation and differentiation and are involved in tumour cell proliferation, invasion, and metastasis ( 124 ).…”