Introduction: Mantle cell lymphoma (MCL) is an incurable disease and we have previously shown that presence of CD163+ cells in the tumor microenvironment in MCL is associated with an adverse outcome. We therefore profiled CD163+ cells to better understand their impact on this tumor and identify possible targetable markers. We hypothesize that, not only the presence of CD163+ cells, a marker of M2 macrophages, in the tumor tissue, but also the spatial context of CD163+ cells might be relevant for MCL development and treatment response.

Material and Methods: Sixty-nine protein targets were measured by the Nanostring GeoMx Digital Spatial Profiler. This method allowed for preserved spatial context, in tissue microarrays from a population-based cohort of de novo MCL patients while investigating different markers. A total of 235 cores from 131 different patients were sampled. Regions of interest for CD20+, CD3+ and CD163+ cells were selected, with more than 600 areas of illumination (AOI) collected. From those, 85 AOI, belonging to 61 patients, were from CD163+ cells. These were subsequently classified according to their spatial profile: CD163+ cells within the tumor area and CD163+ cells excluded from the tumor area. Differentially expressed proteins between different tissue types were also explored.

Results: Among the highest expressed proteins in the CD163 AOI were CD45, HLA-DR and CD68. The higher expression of both HLA-DR and CD68 suggests that macrophages in MCL microenvironment may display mixed phenotypes between pro- and anti-inflammatory stages, the called M1 and M2 polarization types. Interestingly, p53 and Ki67 were highly correlated among the CD163 AOI collected, which might suggest higher aggressiveness of CD163+ cells. We explored the differently expressed proteins between CD163 AOI sampled located within the tumor and excluded from the tumor/tumor barrier. We identified significant differences in the expressed proteins between the two groups, such as p53, VISTA, ARG1, LAG3 and HLA-DR. p53 was higher in the CD163 AOI within the tumor area, whereas VISTA was highest expressed in CD163 AOI excluded from the tumor cells/tumor barrier. Among the 85 CD163+ AOIs, 47 were sampled from lymph node biopsies, 14 from bone marrow, 10 from tonsil samples, four from the gastrointestinal tract, six from other tissue types and four from unknown origin. Principal component analysis and k-means clustering showed that most of bone marrow and gastrointestinal tract biopsies clustered apart from the remaining samples, with a few differentially expressed proteins, such as NF1 and CD66b.

Conclusions: Our study demonstrates that spatial localization within the MCL tumor affects the expression of CD163+ macrophages, adding to the premise that macrophages in tumor are not easily characterized by the concept of M1 and M2 types. Our results shed light on targetable features of the MCL tumor microenvironment.

Citation Format: Joana Matos Rodrigues, Lavanya Lokhande, Anna Gerdtsson, Anna Nikkarinen, Peter Hollander, Anna Porwit, Ingrid Glimelius, Mats Jerkeman, Sara Ek. Spatially resolved multiplexed analysisreveals how macrophages adapt to the mantle cell lymphoma microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2026.