The Relationship Between Tumor-Stroma Ratio, the Immune Microenvironment, and Survival in Patients With Spinal Chordoma

BACKGROUND

Currently, little is known about the clinical relevance of tumor-stroma ratio (TSR) in chordoma and data discussing the relationship between TSR and immune status of chordoma are lacking.

OBJECTIVE

To characterize TSR distribution in spinal chordoma, and investigated its correlation with clinicopathologic or immunological features of patients and outcome.

METHODS

TSR was assessed visually on hematoxylin and eosin-stained sections from 54 tumor specimens by 2 independent pathologists. Multiplex immunofluorescence was used to quantify the expression levels of microvessel density, Ki-67, Brachyury, and tumor as well as stromal PD-L1. Tumor immunity status including the Immunoscore and densities of tumor-infiltrating lymphocytes (TILs) subtypes were obtained from our published data and reanalyzed.

RESULTS

Bland-Altman plot showed no difference between mean TSR derived from the two observers. TSR was positively associated with stromal PD-L1 expression, the Immunoscore and CD3+ as well as CD4+ TILs density, but negatively correlated with tumor microvessel density, Ki-67 index, surrounding muscle invasion by tumor and number of Foxp3+ and PD-1+ TILs. Low TSR independently predicted poor local recurrence-free survival and overall survival. Moreover, patients with low TSR and low Immunoscore chordoma phenotype were associated with the worst survival. More importantly, combined TSR and Immunoscore accurately reflected prognosis and enhanced the ability of TSR or Immunoscore alone for outcome prediction.

CONCLUSION

These data reveal the significant impact of TSR on tumor progression and immunological response of patients. Subsequent use of agents targeting the stroma compartment may be an effective strategy to treat chordoma especially in combination with immune-based drugs.

Clinicopathological and Prognostic Characteristics in Extra-Axial Chordomas: An Integrative Analysis of 86 Cases and Comparison With Axial Chordomas

BACKGROUND

Currently, clinical characteristics and prognostic factors of extra-axial chordoma (EAC) remain poorly understood.

OBJECTIVE

To characterize clinicopathological characteristics in a large EAC cohort and investigate their correlation with survival. We also attempted to compare these outcomes with axial chordoma (AC).

METHODS

Medline and Embase searches (from inception to February 28, 2018) were conducted to identify eligible studies as per predefined criteria. The local database at our center was also retrospectively reviewed to include additional patients.

RESULTS

Forty-three studies from the literature and 86 patients from our local institute were identified, resulting in a total of 86 EAC patients and 75 AC patients for analysis. Overall, EAC had similar characteristics to AC, except for having higher CAM5.2 expression, common lobular growth pattern, and better prognosis. Whereas wide surgical resection was consistently associated with favorable survival in both EAC and AC cohorts on univariate analyses, most parameters showed differential prognostic implications between the 2 groups. Significant prognostic factors for local recurrence-free survival on multivariate analysis included type of surgery in both cohorts and tumor Brachyury expression and adjuvant radiotherapy in AC cohort. Multivariate analysis of overall survival demonstrated that type of surgery, tumor Brachyury expression, and duration of symptoms were significant predictors in the AC cohort, whereas none of the analyzed parameters were predictive of overall survival for the EAC group.

CONCLUSION

These data suggest potentially distinct biological behaviors between EAC and AC and may provide useful information to better understand the prognostic characteristics and improve the outcome prediction of EAC patients.

Clinical Impact of the Immune Microenvironment in Spinal Chordoma: Immunoscore as an Independent Favorable Prognostic Factor

BACKGROUND

Currently, clinical implications of immune system cells in chordoma remain to be elucidated.

OBJECTIVE

To characterize in situ immune cell infiltrates, the Immunoscore, and investigate their correlation with clinicopathologic data of spinal chordoma patients and outcome.

METHODS

Tumor-infiltrating lymphocytes (TILs) subtypes were assessed in 54 tumor specimens using immunohistochemistry for CD3, CD4, CD8, CD20, Foxp3, PD-1, and PD-L1.

RESULTS

Overall, immune cell infiltrates were present in all samples and there was low or moderate correlation among several TILs subsets. PD-1+ TILs density, CD3+, and CD8+ TILs densities in the tumor interior (TI) subarea were associated with surrounding muscle invasion by tumor, whereas PD-L1+ TILs showed inverse association with tumor pathological grade and stage. The density of PD-1+ TILs, PD-L1+ TILs, CD4+ TILs, and CD3+ TILs both in the TI and combined tumor regions (TI and invasion margin) were significantly associated with local recurrence-free survival and overall survival (OS). However, Foxp3+ TILs (P = .024) and CD8+ TILs evaluated in the TI (P < .001) only correlated with OS. The Immunoscore predicted less aggressive clinical features and favorable outcomes. Patients with an Immunoscore of 4 had a median OS of 128 mo, while I0 (Immunoscore of 0) patients survived only 27 mo. Multivariate analysis demonstrated that the Immunoscore was an independent favorable prognostic factor of both local recurrence-free survival (P = .026) and OS (P = .046).

CONCLUSION

Our data suggest a clinically relevant role of the immune microenvironment in spinal chordoma and identify the Immunoscore as promising prognostic marker.

Clinicopathologic implications of CD8+/Foxp3+ ratio and miR-574-3p/PD-L1 axis in spinal chordoma patients

Currently, little is known about the interactions between microRNAs (miRNAs) and the PD-1/PD-L1 signaling pathway in chordoma, and data discussing the role of the immune milieu in chordoma prognosis are limited. We aimed to analyze the relationship between PD-L1, miR-574-3p, microenvironmental tumor-infiltrating lymphocytes (TILs) and clinicopathological features of spinal chordoma patients. PD-L1 expression and TILs (including Foxp3+, CD8+, PD-1+ and PD-L1+) were assessed by immunohistochemistry in tumor specimens of 54 spinal chordoma patients. MiRNAs microarray and bioinformatical analysis were used to identify miRNAs potentially regulating PD-L1 expression, which were further validated by quantitative RT-PCR. miR-574-3p was identified to potentially regulate PD-L1 expression in chordoma, which inversely correlated with PD-L1. Positive PD-L1 expression on tumor cells was associated with advanced stages (P = 0.041) and TILs infiltration (P = 0.005), whereas decreased miR-574-3p level correlated with higher muscle invasion (P = 0.012), more severe tumor necrosis (P = 0.022) and poor patient survival. Importantly, a patient subgroup with PD-L1+/miR-574-3plow chordoma phenotype was significantly associated with worse local recurrence-free survival (LRFS) (P = 0.026). PD-1+ TILs density was associated with surrounding muscle invasion (P = 0.014), and independently portended poor LRFS (P = 0.040), while PD-L1+ TILs showed tendencies of less aggressive clinical outcomes. Multivariate analysis of OS only found CD8+/Foxp3+ ratio to be independent prognostic factor (P = 0.022). These findings may be useful to stratify patients into prognostic groups and provide a rationale for the use of checkpoint blockade therapy, possibly by administering miR-574-3p mimics, in spinal chordoma.