Chordomas are primary bone
tumors that arise in the cranial base, mobile spine, and sacrococcygeal region, affecting patients of all ages. Currently, there are no approved agents for
chordoma patients. Here, we evaluated the anti-
tumor efficacy of small molecule inhibitors that target oncogenic pathways in
chordoma, as single agents and in combination, to identify novel therapeutic approaches with the greatest translational potential. A panel of small molecule compounds was screened in vivo against patient-derived xenograft (PDX) models of
chordoma, and potentially synergistic combinations were further evaluated using
chordoma cell lines and xenograft models. Among the tested agents, inhibitors of EGFR (BIBX 1382,
erlotinib, and
afatinib), c-MET (
crizotinib), and mTOR (
AZD8055) significantly inhibited
tumor growth in vivo but did not induce
tumor regression. Co-inhibition of EGFR and c-MET using
erlotinib and
crizotinib synergistically reduced cell viability in
chordoma cell lines but did not result in enhanced in vivo activity. Co-inhibition of EGFR and mTOR pathways using
afatinib and
AZD8055 synergistically reduced cell viability in
chordoma cell lines. Importantly, this dual inhibition completely suppressed
tumor growth in vivo, showing improved
tumor control. Together, these data demonstrate that individual inhibitors of EGFR, c-MET, and mTOR pathways suppress
chordoma growth both in vitro and in vivo. mTOR inhibition increased the efficacy of EGFR inhibition on
chordoma growth in several preclinical models. The insights gained from our study potentially provide a novel combination therapeutic strategy for patients with
chordoma. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.