Prognostic value of regulatory T cells, lymphoma-associated macrophages, and MUM-1 expression in follicular lymphoma treated before and after the introduction of monoclonal antibody therapy: a Southwest Oncology Group Study

Abstract

Background: The purpose was to examine the prognostic impact of features of tumor cells and immune microenvironment in patients with follicular lymphoma treated with and without anti-CD20 monoclonal antibody therapy.

Patients and methods: Tissue microarrays were constructed from archived tissue obtained from patients on three sequential Southwest Oncology Group (SWOG) trials for FL. All three trials included anthracycline-based chemotherapy. Anti-CD20 monoclonal antibodies were included for patients in the latter two trials. Immunohistochemistry was used to study the number and distribution of cells staining for forkhead box protein P3 (FOXP3) and lymphoma-associated macrophages (LAMs) and the number of lymphoma cells staining for myeloma-associated antigen-1 (MUM-1). Cox proportional hazards regression was used to evaluate the association between marker expression and overall survival (OS).

Results: The number or pattern of infiltrating FOXP3 cells and LAMs did not correlate with OS in sequential SWOG studies for FL. The presence of MUM-1 correlated with lower OS for patients who received monoclonal antibody but not for those treated with chemotherapy alone.

Conclusions: Immune cell composition of lymph nodes did not correlate with OS in this analysis of trials in FL. The mechanism of the observed correlation between MUM-1 expression and adverse prognosis in patients receiving monoclonal antibody therapy requires confirmation.

Figures

Figure 1.

Examples of immunostaining. (A,D) CD68 stain showing low and high numbers of macrophages, respectively. (B,E) Forkhead box protein staining shows a perifollicular pattern (B). High magnification shows nuclear expression (E). (C,F) A case showing expression of myeloma-associated antigen-1 at low (C) and high (F) magnifications. For all images, low magnification = ×100, whereas high magnification = ×400 (original magnification).

Figure 2.

Overall survival according to myeloma-associated antigen-1 expression for patients receiving chemotherapy plus monoclonal antibody on studies S9800 and S9911 (A) and chemotherapy only on study S8809 (B).

Figure 3.

Dual myeloma-associated antigen-1 (MUM-1)/bcl-6 quantum dot immunofluorescence. Sections were stained with MUM-1 (Qdot 605) and bcl-6 (Qdot655) and counterstained with diamidino-2-phenylindole to highlight nuclei. Images were digitally colorized (MUM-1 green and bcl-6 red). The left panels show MUM-1 alone, middle panel bcl-6 alone, and right panels show combined overlay in the same microscopic field. The top row shows a reactive germinal center from a tonsil in which only rare cells express MUM-1, numerous cells express bcl-6, and only a single cell coexpresses the two proteins (circle). The middle row, from a MUM-1-negative follicular lymphoma (FL), shows malignant FL cells expressing only bcl-6. The bottom row, from a MUM-1-positive FL, shows several MUM-1-expressing cells and numerous bcl-6-expressing cells. The MUM-1 and bcl-6 colocalize (circles).