Chordomas are rare primary bone
tumors that occur along the neuraxis. Primary treatment is surgery, often followed by
radiotherapy. Treatment options for patients with recurrence are limited and, notably, there are no FDA approved therapeutic agents. Development of therapeutic options has been limited by the paucity of preclinical model systems. We have established and previously reported the initial characterization of the first patient-derived
chordoma xenograft model. In this study, we further characterize this model and demonstrate that it continues to resemble the original patient
tumor histologically and immunohistochemically, maintains nuclear expression of
brachyury, and is highly concordant with the original patient
tumor by whole genome genotyping. Pathway analysis of this xenograft demonstrates activation of
epidermal growth factor receptor (EGFR). In vitro studies demonstrate that two small molecule inhibitors of EGFR,
erlotinib and
gefitinib, inhibit proliferation of the
chordoma cell line U-CH 1. We further demonstrate that
erlotinib significantly inhibits
chordoma growth in vivo. Evaluation of
tumors post-treatment reveals that
erlotinib reduces phosphorylation of EGFR. This is the first demonstration of antitumor activity in a patient-derived
chordoma xenograft model and these findings support further evaluation of EGFR inhibitors in this disease.