Clinicopathological implications of TIM3+ tumor-infiltrating lymphocytes and the miR-455-5p/Galectin-9 axis in skull base chordoma patients

Chordoma is difficult to eradicate due to high local recurrence rates. The immune microenvironment is closely associated with tumor prognosis; however, its role in skull base chordoma is unknown. The expression of Galectin-9 (Gal9) and tumor-infiltrating lymphocyte (TIL) markers was assessed by immunohistochemistry. Kaplan-Meier and multivariate Cox analyses were used to assessing local recurrence-free survival (LRFS) and overall survival (OS) of patients. MiR-455-5p was identified as a regulator of Gal9 expression. Immunopositivity for Gal9 was associated with tumor invasion (p=0.019), Karnofsky performance status (KPS) score (p=0.017), and total TIL count (p<0.001); downregulation of miR-455-5p was correlated with tumor invasion (p=0.017) and poor prognosis; and the T-cell immunoglobulin and mucin-domain 3 (TIM3)(+) TIL count was associated with chordoma invasion (p=0.010) and KPS score (p=0.037). Furthermore, multivariate analysis indicated that only TIM3(+) TIL density was an independent prognostic factor for LRFS (p=0.010) and OS (p=0.016). These results can be used to predict clinical outcome and provide a basis for immune therapy in skull base chordoma patients.