Development and validation of a stromal-immune signature to predict prognosis in intrahepatic cholangiocarcinoma

Abstract

Backgrounds/aims: Intrahepatic cholangiocarcinoma (ICC) is a highly desmoplastic tumor with poor prognosis even after curative resection. We investigated the associations between the composition of the ICC stroma and immune cell infiltration and aimed to develop a stromal-immune signature to predict prognosis in surgically treated ICC.

Methods: We recruited 359 ICC patients and performed immunohistochemistry to detect α-smooth muscle actin (α-SMA), CD3, CD4, CD8, Foxp3, CD68, and CD66b. Aniline was used to stain collagen deposition. Survival analyses were performed to detect prognostic values of these markers. Recursive partitioning for a discrete-time survival tree was applied to define a stromal-immune signature with distinct prognostic value. We delineated an integrated stromal-immune signature based on immune cell subpopulations and stromal composition to distinguish subgroups with different recurrence-free survival (RFS) and overall survival (OS) time.

Results: We defined four major patterns of ICC stroma composition according to the distributions of α-SMA and collagen: dormant (α-SMAlow/collagenhigh), fibrogenic (α-SMAhigh/collagenhigh), inert (α-SMAlow/collagenlow), and fibrolytic (α-SMAhigh/collagenlow). The stroma types were characterized by distinct patterns of infiltration by immune cells. We divided patients into six classes. Class I, characterized by high CD8 expression and dormant stroma, displayed the longest RFS and OS, whereas Class VI, characterized by low CD8 expression and high CD66b expression, displayed the shortest RFS and OS. The integrated stromal-immune signature was consolidated in a validation cohort.

Conclusion: We developed and validated a stromal-immune signature to predict prognosis in surgically treated ICC. These findings provide new insights into the stromal-immune response to ICC.

Keywords: Immune cell; Intrahepatic cholangiocarcinoma; Prognosis; Stromal signature.

Figure 1.

Tumor stromal composition is associated with prognosis in ICC. (A) Stromal composition of different stromal types. (B) K-M curves of RFS and OS among stromal composition and different stromal types. ICC, intrahepatic cholangiocarcinoma; RFS, recurrencefree survival; OS, overall survival; α-SMA, α-smooth muscle actin.

Figure 2.

Interactive of tumor infiltrated leukocytes regarding different stromal types. (A) Distribution of different tumor infiltrated leukocytes in different stromal types. (B) Comparative correlation analysis of tumor infiltrated leukocytes in different stroma types.

Figure 3.

Integrating prognostic stromal-immune signature to predict recurrence-free survival. (A) Recursive partition survival tree defines the stromal-immune signature with separate median RFS and OS. (B) Pairwise survival analysis of stromal-immune signature with Bonferroni adjustment in left low triangle and none adjustment in right upper triangle for RFS and OS. (C) Boxplot illustrates the prognostic index by Cox multivariate model in different stromal-immune signature. RFS, recurrence-free survival; OS, overall survival.