Efficacy of afatinib or osimertinib plus cetuximab combination therapy for non-small-cell lung cancer with EGFR exon 20 insertion mutations
Introduction
Lung cancer is a leading cause of cancer-related deaths worldwide [1]. However, in recent decades, the elucidation of key molecular mechanisms contributed to the improvement of prognosis in patients with lung cancer, especially in those with non-small cell lung cancer (NSCLC) [2]. In 2004, an association between somatic mutations in the tyrosine kinase domain of epidermal growth factor receptor (EGFR) gene and the response to EGFR tyrosine kinase inhibitor (TKI) treatment were reported by several groups [3,4]. Among the EGFR mutations found in NSCLC, in-frame deletions near the LREA motif in exon 19 (exon 19 deletions) and the L858R point mutation in exon 21 are classic mutations, accounting for approximately 80–90% of EGFR mutations [5]. These mutations destabilize the inactive conformation of EGFR and induce its constitutive activation [[6], [7], [8]]. Activated EGFR transduces downstream signaling, including the extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase (MAPK) and phosphatidylinositol-3-kinase/protein kinase B (AKT) pathways [5,9]. After this discovery, multiple clinical trials demonstrated the efficacy of EGFR-TKIs in NSCLC patients carrying classic EGFR mutations [[10], [11], [12], [13]]. Multiple EGFR-TKIs, including gefitinib, erlotinib (first-generation), afatinib, dacomitinib (second-generation), and osimertinib (third-generation), are in clinical use for the treatment of NSCLC patients with these EGFR mutations [[14], [15], [16]]. However, the EGFR exon 20 insertion mutations are reportedly associated with resistance to EGFR-TKIs [17,18]. One exception is A763_Y764insFQEA, which we identified as an EGFR-TKI sensitive EGFR exon 20 insertion mutation [18]. EGFR exon 20 insertion mutations account for approximately 4–10% of all EGFR mutations associated with NSCLC [19]. Afatinib had a response rate of 8.3% in EGFR exon 20 insertion mutation-positive NSCLC, indicating the limited efficacy of EGFR-TKIs against this subgroup of NSCLC [19]. To improve the prognosis in NSCLC patients harboring EGFR exon 20 insertion mutations, the development of an effective therapy is urgently needed. Our study findings show that cetuximab combination therapy would be a potential strategy for the treatment of these patients.
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Reagents
Erlotinib and afatinib were purchased from LC Laboratories (Woburn, MA, USA). Osimertinib was purchased from Selleck Chemicals (Houston, TX, USA). Cetuximab was purchased from Keio University Hospital (Tokyo, Japan). Total EGFR antibody (#2232), total AKT antibody (#9272), phospho-AKT (S473; D9E) antibody (#4060), total p44/42 MAPK antibody (#9102S), and phospho-p44/42 MAPK (T202/204) antibody (#9101S) were purchased from Cell Signaling Technology (Beverly, MA, USA). Phospho-EGFR (Y1068)
Efficacy of afatinib or osimertinib plus cetuximab combination therapy on EGFR exon 20 insertion mutations
To evaluate the efficacy of cetuximab on EGFR exon 20 insertion mutations, we performed the MTS cell proliferation assay with cetuximab in a panel of Ba/F3 cells transduced with EGFR exon 20 insertion mutations (A767_V769dupASV, A764_V765insHH, D770_N771insNPG, and A763_Y764 in. FQEA). Except for EGFR A763_Y764insFQEA, an EGFR-TKI sensitive mutation, cetuximab did not induce an efficient inhibition of Ba/F3 cell proliferation (Fig. 1). These data indicated that cetuximab monotherapy has no
Discussion
In this study, we evaluated the in vitro and in vivo efficacy of afatinib or osimertinib plus cetuximab combination therapy on EGFR exon 20 insertion mutations. An earlier report indicated a limited efficacy of 1st- and 2nd-generation EGFR-TKIs in NSCLC with EGFR exon 20 insertion mutations [19]. Therefore, NSCLC patients carrying these mutations cannot be effectively treated with EGFR-TKIs. Recently, we reported preclinical evidence for the potential efficacy of osimertinib on EGFR exon 20
Funding
This work was supported in part by the Grants-in-Aid for Scientific Research on Priority Areas from the Ministry of Education, Culture, Sports, Science, and Technology of Japan to K.S. (15K09229), T.B. (15H04833), H.Y. (17K09667) and H.T. (18K08184). This work was supported in part by Takeda Science Foundation to H. Yasuda and H. Terai.
Conflicts of interest statement
There are no potential conflicts of interest to disclose.
Acknowledgements
We would like to thank Professor Tomoko Betsuyaku for financial assistance and technical advice. We are grateful to Ms. Mikiko Shibuya for her excellent technical assistance. We are also grateful to the Collaborative Research Resources at the Keio University School of Medicine for assistance with cell sorting.
References (26)
- et al.
Structures of lung cancer-derived EGFR mutants and inhibitor complexes: mechanism of activation and insights into differential inhibitor sensitivity
Cancer Cell
(2007) - et al.
Catalytic control in the EGF receptor and its connection to general kinase regulatory mechanisms
Mol. Cell
(2011) - et al.
An allosteric mechanism for activation of the kinase domain of epidermal growth factor receptor
Cell
(2006) - et al.
G. West Japan Oncology, Gefitinib versus cisplatin plus docetaxel in patients with non-small-cell lung cancer harbouring mutations of the epidermal growth factor receptor (WJTOG3405): an open label, randomised phase 3 trial, The Lancet
Oncology
(2010) - et al.
Erlotinib versus chemotherapy as first-line treatment for patients with advanced EGFR mutation-positive non-small-cell lung cancer (OPTIMAL, CTONG-0802): a multicentre, open-label, randomised, phase 3 study, the Lancet
Oncology
(2011) - et al.
Afatinib and cetuximab in four patients with EGFR exon 20 insertion-positive advanced NSCLC
J. Thorac. Oncol.
(2018) - et al.
Cancer statistics, 2016
CA Cancer J. Clin.
(2016) N. Cancer Genome Atlas Research, comprehensive molecular profiling of lung adenocarcinoma
Nature
(2014)- et al.
Activating mutations in the epidermal growth factor receptor underlying responsiveness of non-small-cell lung cancer to gefitinib
N. Engl. J. Med.
(2004) - et al.
EGF receptor gene mutations are common in lung cancers from "never smokers" and are associated with sensitivity of tumors to gefitinib and erlotinib
Proc. Natl. Acad. Sci. U. S. A.
(2004)