Afatinib Is a New Therapeutic Approach in Chordoma with a Unique Ability to Target EGFR and Brachyury

Abstract

Chordomas are rare bone tumors with no approved therapy. These tumors express several activated tyrosine kinase receptors, which prompted attempts to treat patients with tyrosine kinase inhibitors. Although clinical benefit was observed in phase II clinical trials with imatinib and sorafenib, and sporadically also with EGFR inhibitors, therapies evaluated to date have shown modest activity. With the goal of identifying new drugs with immediate therapeutic potential for chordoma patients, we collected clinically approved drugs and other advanced inhibitors of MET, PDGFRβ, and EGFR tyrosine kinases, and assessed their antiproliferative activity against a panel of chordoma cell lines. Chordoma cell lines were not responsive to MET and PDGFRβ inhibitors. U-CH1 and UM-Chor1 were sensitive to all EGFR inhibitors, whereas the remaining cell lines were generally insensitive to these drugs. Afatinib was the only EGFR inhibitor with activity across the chordoma panel. We then investigated the molecular mechanisms behind the responses observed and found that the antiproliferative ICs correlate with the unique ability of afatinib to promote degradation of EGFR and brachyury, an embryonic transcription factor considered a key driver of chordoma. Afatinib displayed potent antitumor efficacy in U-CH1, SF8894, CF322, and CF365 chordoma tumor models In the panel analyzed, high EGFR phosphorylation and low AXL and STK33 expression correlated with higher sensitivity to afatinib and deserve further investigation as potential biomarkers of response. These data support the use of afatinib in clinical trials and provide the rationale for the upcoming European phase II study on afatinib in advanced chordoma..

An update of molecular pathology of bone tumors. Lessons learned from investigating samples by next generation sequencing

“…Clinically actionable PI3K signaling mutations including PIK3CA , PIK3R1 , and PTEN have been identified in 16% of cases, although clinical trials are required to determine the clinical value of such targeted therapies. Although EGFR mutations have not been identified in chordomas, the phosphorylated protein is expressed in the majority of cases, and therapeutic compounds have been found to induce chordoma cell death in vitro . This research has resulted in the opening of a recent phase II clinical trial using Afatinib, a third generation EGFR inhibitor.…”

“…Although EGFR mutations have not been identified in chordomas, the phosphorylated protein is expressed in the majority of cases, and therapeutic compounds have been found to induce chordoma cell death in vitro. [56][57][58] This research has resulted in the opening of a recent phase II clinical trial using Afatinib, a third generation EGFR inhibitor. Finally, cancer driver events have also been identified in chromatin remodeling genes including SETD2, ARID1A, and PBRM1 raising the possibility that chordoma may be susceptible to epigenetic inhibitors.…”

Targeting an EGFR Water Network with 4‐Anilinoquin(az)oline Inhibitors for Chordoma

“…Anumber of EGFRinhibitors have been identifiedt hat are active in cellular models of chordoma, with afatinib currently in phase 2c linical trials for the treatment of chordoma ( Figure 1). [9][10][11][12] Kinasei nhibitors commonly have off-targets across the kinomet hat confound the ability to accurately define the mechanism of action that cause induction of phenotypes of interest. [13] The 4-anilinoquinoline and 4-anilinoquinazoline scaf- folds have demonstrated ar ange of activity profiles across the kinome from highly selectivet ob roadly promiscuous.…”

Epigenetic inactivation of oncogenic brachyury (TBXT) by H3K27 histone demethylase controls chordoma cell survival

“…To our knowledge, this is the first time that such a compound has been shown consistently to induce cell death across a number of chordoma cell lines and to reduce simultaneously expression of TBXT. Previously, we and others have shown that treatment with EGFR inhibitors lead to decreased chordoma cell viability (16,17,35), however, the results are variable across different cell lines, and reduction of TBXT expression was seen in response to only one EGFR inhibitor, afatinib (16,17). The finding that suppression of TBXT expression and reduced cell survival by H3K27 demethylase inhibition occurred in all tested chordoma cell lines and 4 genomically heterogeneous primary chordoma samples provides compelling evidence that the cellular response to the employed tool compound is consistent.…”

“…survival, and they have seen little benefit from genomic studies seeking tractable therapeutic targets such as protein kinases (15). Small molecule-focused compound screens against chordoma cell lines in vitro have also yielded limited success with few compounds showing inhibition of cell growth: EGFR inhibitors were one of the rare exceptions, results which have led to a phase 2 clinical trial (16,17). Although encouraging, this treatment is unlikely to benefit all patients as not all cell lines were responsive, and the rapid development of resistance to EGFR inhibitors in clinical practice is widely documented (18).…”