Expression of costimulatory molecule CD70 is prognostic in small cell lung cancer

Abstract

Introduction: Small cell lung cancer (SCLC) is a highly aggressive malignancy with poor survival outcomes. The CD70-CD27 axis has been implicated in immune regulation and tumor progression across cancers, but its role in SCLC has not yet been elucidated. This research explores the expression patterns and prognostic significance of CD70 and CD27 in early-stage SCLC.

Methods: In this retrospective study, we analyzed 190 surgically resected SCLC tumor samples using immunohistochemistry (IHC) for CD70 and CD27 expression and RNAscope for CD70 RNA detection. Immune infiltration was assessed using CD45, CD8, and CD20 staining. Quantification of RNAscope signals was performed using QPath software. Kaplan-Meier survival analysis and multivariate Cox regression were used to assess the prognostic impact of CD70, CD27, and immune cell infiltrates on overall survival (OS).

Results: CD70 was expressed in 46% of tumors, primarily within tumor nests, with lower expression in stromal areas. High CD70 expression correlated with significantly decreased OS (p = 0.0078, HR: 1.795) without any correlation with CD45 + , CD8 + or CD20 + immune cell infiltrates. CD27 expression was mainly confined to the stroma, and it did not show a significant association with OS (p = 0.582). Importantly, high CD27 expression was linked to reduced CD45 + and CD8 + cell densities in the stroma. Both CD70 and CD27 were expressed on CD68 + macrophages, CD27 was expressed on CAFs, and both molecules exhibited a partial coexpression with CD3. Furthermore, patients with high CD20 + B-cell densities or the presence of tertiary lymphoid structures (TLS) had significantly improved OS (p = 0.0017, HR: 0.491), suggesting the importance of B-cell-related immune responses in SCLC prognosis.

Conclusion: CD70, B-cell density and the presence of TLSs, but not CD27, emerged as a significant prognostic biomarker for OS in surgically treated SCLC, suggesting its potential as a therapeutic target.

Keywords: B-cell; CD27; CD70; Small-cell lung cancer; TLS; Tumor microenvironment.

Fig. 1

Expression of the CD70-CD27 axis in NSCLC. Single-cell data from the SingleCell portal show expression means and percentage of expressing cells in dot plots comparing CD70 and CD27, according to included patients (A) and major cell types (B). UMAP plots show the number and cluster of cells expressing CD70 (C) and CD27 (D). CD70 is expressed in B-cells, CD4 + T-cells (naive, memory), T-regs, and eosinophils within the NSCLC tumor microenvironment according to the LM22 signature matrix file (E, F). CD27 is primarily expressed in plasma cells, T-regs, follicular helper T-cells, and other CD4 + T-cell populations based on the same dataset (E, G). Row minimums and maximums (RNA expression, Log(CP10k + 1) normalized counts matrix (genes by cells)) in panel A are color coded. Size of corresponding circles correlates with the percentage of expressing cells for every cell type in dot plots

Fig. 2

Expression of CD70 and CD27 in SCLC. RNAscope assays revealed CD70 expression predominantly in tumor nests (A,B, dashed line delimited areas) and scattered in stroma (A, arrows), with most tumors scoring 1.0–2.0 (B,C). Tumors with CD70 scores of 2.0–3.0 were classified as “high,” and 0–1.5 as “low.” Histogram shows distribution of CD70 scores (D). CD70 expression was not significantly associated with CD45 + or CD8 + cell densities in stroma or tumor nests (E–H). CD27 was primarily expressed in stroma (I-L). Distribution of CD27 aggregate scores through tumor samples is shown in panel M. High CD27 + cellular density was linked to reduced CD45 + and CD8 + cell densities (N,P), but not in tumor nests (O,Q). Metric data are shown as medians and 95% CI on violin plots. Statistical significance *P < 0.05; **P < 0.01, ***P < .001. All p values were two-sided

Fig. 3

B-cells in SCLC in the context of the CD70-CD27 axis. CD20 + B-cell densities were evaluated in the SCLC cohort using the same scoring method as in the case of CD27. B-cells are primarily located in stromal bands, with occasional intratumoral presence and TLS formation (A, B). Multiple tumors showed signs of formation of tertiary lymphatic structures (TLSs) made up from congregations of CD20 + B-cells (C,D, dashed line delimited area). No significant association was found between CD70/CD27 expression and B-cell densities or TLS presence (E–H, J, K). Metric data are shown as medians and 95% CI on violin plots. Statistical significance *P < 0.05; **P < 0.01, ***P < .001. All p values were two-sided

Fig. 4

Coexpression of CD70 and CD27 on TME cells. Double IF staining revealed a diffuse CD70 protein signal in tumor nests, showing complementarity with vimentin in CD70-high patients, with lower CD70 expression in vimentin-positive tumor cells (A, ellipsoid area within dashed line delimited area for tumor nest). CD70 was expressed by vimentin-positive CAFs in the stroma (B, arrow) and CD68 + TAMs in both stroma and tumor nests (C, arrows, D). However, not all TAMs showed coexpression (C, asterisks). In CD70-high tumors, only a fraction of CD3 + T-cells expressed CD70 (E,F, arrows), while CD20 + B-cells showed no coexpression with CD70 (G,H, asterisks). CD27 was limited to the TME, with occasional vimentin coexpression on CAFs (I, arrow). Multiple CD3 + T-cells (J, arrows), and CD68 + TAMs (K, arrows) also coexpressed CD27

Fig. 5

CD70 and CD27 expression and B-cell densities in the context of overall survival. CD70-high (1) patients showed significantly decreased OS compared to CD70-low (0) patients (p = 0.0078, HR: 1.795, A. CD70 was also prognostic including only patients with immune-oasis (infiltrated) tumors (p = 0.0346, HR: 2.21, B, but not in the population with immune-desert tumors (p = 0.115, C. CD27 (high (1) vs low (0)) expression did not significantly impact OS, neither in the whole cohort D nor in the immune-oasis (infiltrated) E or desert population F. In contrast, B-cell density was prognostic, with increased OS for patients with high (1) stromal/intratumoral B-cell infiltration (p = 0.0017, G,H) and TLS presence (1) (p = 0.0323, HR: 0.48,I)