High Densities of Tumor-Associated Plasma Cells Predict Improved Prognosis in Triple Negative Breast Cancer

Front Immunol. 2018 May 30:9:1209. doi: 10.3389/fimmu.2018.01209. eCollection 2018.

Abstract

Breast cancer is the most common malignancy affecting women, but the heterogeneity of the condition is a significant obstacle to effective treatment. Triple negative breast cancers (TNBCs) do not express HER2 or the receptors for estrogen or progesterone, and so often have a poor prognosis. Tumor-infiltrating T cells have been well-characterized in TNBC, and increased numbers are associated with better outcomes; however, the potential roles of B cells and plasma cells have been large. Here, we conducted a retrospective correlative study on the expression of B cell/plasma cell-related genes, and the abundance and localization of B cells and plasma cells within TNBCs, and clinical outcome. We analyzed 269 TNBC samples and used immunohistochemistry to quantify tumor-infiltrating B cells and plasma cells, coupled with NanoString measurement of expression of immunoglobulin metagenes. Multivariate analysis revealed that patients bearing TNBCs with above-median densities of CD38+ plasma cells had significantly better disease-free survival (DFS) (HR = 0.44; 95% CI 0.26-0.77; p = 0.004) but not overall survival (OS), after adjusting for the effects of known prognostic factors. In contrast, TNBCs with higher immunoglobulin gene expression exhibited improved prognosis (OS p = 0.029 and DFS p = 0.005). The presence of B cells and plasma cells was positively correlated (p < 0.0001, R = 0.558), while immunoglobulin gene IGKC, IGHM, and IGHG1 mRNA expression correlated specifically with the density of CD38+ plasma cells (IGKC p < 0.0001, R = 0.647; IGHM p < 0.0001, R = 0.580; IGHG1 p < 0.0001, R = 0.655). Interestingly, after adjusting the multivariate analysis for the effect of intratumoral CD38+ plasma cell density, the expression levels of all three genes lost significant prognostic value, suggesting a biologically important role of plasma cells. Last but not least, the addition of intratumoral CD38+ plasma cell density to clinicopathological features significantly increased the prognostic value for both DFS (ΔLRχ2 = 17.28, p = 1.71E-08) and OS (ΔLRχ2 = 10.03, p = 6.32E-08), compared to clinicopathological features alone. The best combination was achieved by integrating intratumoral CD38+ plasma cell density and IGHG1 which conferred the best added prognostic value for DFS (ΔLRχ2 = 27.38, p = 5.22E-10) and OS (ΔLRχ2 = 21.29, p = 1.03E-08). Our results demonstrate that the role of plasma cells in TNBC warrants further study to elucidate the relationship between their infiltration of tumors and disease recurrence.

Keywords: B cells; immunohistochemistry; plasma cells; triple negative breast cancer; tumor immunology.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Biomarkers, Tumor
  • Female
  • Humans
  • Immunohistochemistry
  • Immunophenotyping
  • Kaplan-Meier Estimate
  • Lymphocyte Count*
  • Lymphocytes, Tumor-Infiltrating / immunology*
  • Lymphocytes, Tumor-Infiltrating / pathology
  • Middle Aged
  • Plasma Cells / immunology*
  • Plasma Cells / pathology
  • Prognosis
  • Tissue Array Analysis
  • Triple Negative Breast Neoplasms / immunology*
  • Triple Negative Breast Neoplasms / mortality*
  • Triple Negative Breast Neoplasms / pathology

Substances

  • Biomarkers, Tumor