Abstract 33P
Background
Despite potential clinical implications, the complexity of tumor immune microenvironment (TIME) of breast cancer (BC) brain metastases (BMs) is still poorly understood. We previously reported that a higher CD4+FoxP3+/CD8+ cell ratio in the stromal compartment and a higher density of CD163+ M2-polarized macrophages are associated with worse overall survival in BCBMs. We here assess the evolution of TIME from primary BC to paired BMs using multiplex immunofluorescence.
Methods
TIME profiling of archival FFPE specimens of paired primary BC and BMs from 25 patients was carried out using two multiplex immunofluorescence panels (CD4, CD8, Granzyme B, FoxP3, CD68, pan-cytokeratin, DAPI; CD3, PD-1, PD-L1, LAG-3, TIM-3, CD163, pan-cytokeratin, DAPI). Variations in immune cell densities were assessed using a paired Wilcoxon test.
Results
In both the tumor and stromal compartment, BMs exhibited a more immunosuppressive TIME with significantly lower lymphocytic (CD3+), T cell (CD8+), and cytotoxic cell (GranzymeB+) infiltration (p<0.001), higher CD4+FoxP3+ infiltration (p<0.001), and a higher CD4+FoxP3+/CD8+ ratio (p<0.01) as compared to primary tumors. Moreover, the lymphocytic infiltrate presented a more immune exhausted phenotype, with higher levels of CD3+PD-1+ (p<0.01) and CD3+PD-1+LAG3+ (p<0.05) cells, in BMs as compared to primary BCs. PD-L1 expression in the tumor compartment was also reduced in BMs compared to primary BCs (p<0.001). In addition, TIM3+ cells were significantly less represented in both the tumor and stromal compartment (p<0.01) On the other hand, BMs presented significantly higher levels of macrophagic (CD68+) infiltration in the tumor compartment (p=0.008) and of CD163+ M2-polarized macrophagic infiltration in the stromal compartment (p<0.001), which was associated with a significant decrease in the CD3/CD163+ ratio in both compartments (p<0.001).
Conclusions
Our results suggest that BCBMs present a more immunosuppressed TIME as compared to primary tumors, comprising immune phenotypes (e.g. immunosuppressive tumor-associated macrophages) that may represent a potential target for immunotherapeutic strategies for BCBMs.
Legal entity responsible for the study
Department of Surgery, Oncology and Gastroenterology - University of Padua.
Funding
The authors acknowledge grants from: Veneto Institute of Oncology IOV-IRCCS, Ricerca Corrente funding; DOR funding from the University of Padua to FM, MVD, VG and GG.
Disclosure
G. Griguolo: Financial Interests, Personal, Invited Speaker: Novartis, Eli Lilly, MSD; Financial Interests, Personal, Advisory Board: Gilead, Menarini, Seagen; Other, Travel Support: Novartis, Amgen, Daiichi Sankyo, Eli Lilly, Gilead; Other, Trave Support: Pfizer. F. Miglietta: Financial Interests, Personal, Invited Speaker: Roche, Novartis, Seagen, Pfizer, Lilly, Menarini; Financial Interests, Personal, Advisory Board: AstraZeneca, MSD. W. Jacot: Financial Interests, Personal, Advisory Board: AstraZeneca, Eisai, Novartis, Roche, Pfizer, Eli Lilly, MSD, BMS, Chugai, Seagen, Daiichi Sankyo; Financial Interests, Personal, Invited Speaker: AstraZeneca, Pfizer, Seagen, Daiichi Sankyo; Financial Interests, Personal, Advisory Board, Advisory Board: Gilead; Financial Interests, Institutional, Research Grant: AstraZeneca, Daiichi Sankyo; Financial Interests, Invited Speaker: Roche, Roche, Novartis, Daiichi Sankyo, Daiichi Sankyo. V. Guarneri: Financial Interests, Personal, Invited Speaker: Eli Lilly, Novartis, GSK, AstraZeneca, Gilead, Exact Sciences; Financial Interests, Personal, Advisory Board: Eli Lilly, Novartis, MSD, Gilead, Merck, Exact Sciences, Eisai, Olema Oncology, AstraZeneca, Daiichi Sankyo, Pfizer; Financial Interests, Personal, Expert Testimony: Eli Lilly; Financial Interests, Institutional, Invited Speaker: Eli Lilly, Roche, BMS, Novartis, AstraZeneca, MSD, Synton Biopharmaceuticals, Merck, GSK, Daiichi Sankyo, Nerviano, Pfizer; Non-Financial Interests, Member: ASCO. A. Darlix: Financial Interests, Personal, Advisory Board: Servier, Novocure. M.V. Dieci: Financial Interests, Personal, Invited Speaker: Eli Lilly, Exact sciences, Gilead, Seagen, Daiichi Sankyo, Novartis; Financial Interests, Personal, Advisory Board: Novartis, Eli Lilly, Seagen, Exact Science, Daiichi Sankyo, Gilead; Financial Interests, Personal, Other, Consultancy: Pfizer; Financial Interests, Personal, Other, Consultancy on educational project: Roche. All other authors have declared no conflicts of interest.