In chordoma, metastasis, recurrences, Ki-67 index, and a matrix-poor phenotype are associated with patients' shorter overall survival.

PURPOSE: To establish a chordoma tissue cohort (n = 43) and to correlate localization, size, metastasis, residual disease (R-status), recurrences, histological subtype, matrix content, and Ki-67 proliferation index with patients' overall survival (OS). METHODS AND RESULTS: We used routine histopathology supplemented by immunohistochemistry. In our patient cohort (median age 69 years, range 17 to 84 years) the median OS was 8.25 years. 24 chordomas were localized in the sacrum, 6 in lumbar vertebrae, 7 in thoracic and cervical vertebrae, 5 were limited to the clivus, and one was localized in the nasal septum. Ten patients had metastases, with pulmonary, nodal, and hepatic involvement. 23 patients had recurrent disease. 23 chordomas were classified as 'not otherwise specified' (NOS). Besides NOS, we found the following differentiation patterns: renal cell cancer like in six cases, chondroid in four cases, hepatoid differentiation in three cases, and anaplastic morphology in six cases. Ki-67 index of ≥10 %, presence of metastasis, and the low content of extracellular matrix were statistically linked to poor OS (p < 0.05). The matrix-poor phenotype had a higher Ki-67 index (p < 0.05). Furthermore, presence of metastasis was associated with a higher Ki-67 index in the primary lesion, a positive resection margin, and multiple recurrences (p < 0.05 each). CONCLUSION: We propose to include these parameters in the final pathologic report of the resected chordoma.

Preclinical Characterization of Novel Chordoma Cell Systems and Their Targeting by Pharmocological Inhibitors of the CDK4/6 Cell-Cycle Pathway.

Chordomas are tumors that arise at vertebral bodies and the base of the skull. Although rare in incidence, they are deadly owing to slow growth and a lack of effective therapeutic options. In this study, we addressed the need for chordoma cell systems that can be used to identify therapeutic targets and empower testing of candidate pharmacologic drugs. Eight human chordoma cell lines that we established exhibited cytology, genomics, mRNA, and protein profiles that were characteristic of primary chordomas. Candidate responder profiles were identified through an immunohistochemical analysis of a chordoma tissue bank of 43 patients. Genomic, mRNA, and protein expression analyses confirmed that the new cell systems were highly representative of chordoma tissues. Notably, all cells exhibited a loss of CDKN2A and p16, resulting in universal activation of the CDK4/6 and Rb pathways. Therefore, we investigated the CDK4/6 pathway and responses to the CDK4/6-specific inhibitor palbociclib. In the newly validated system, palbociclib treatment efficiently inhibited tumor cell growth in vitro and a drug responder versus nonresponder molecular signature was defined on the basis of immunohistochemical expression of CDK4/6/pRb (S780). Overall, our work offers a valuable new tool for chordoma studies including the development of novel biomarkers and molecular targeting strategies.