Retrospective analysis of the immunogenic effects of intra-arterial locoregional therapies in hepatocellular carcinoma: a rationale for combining selective internal radiation therapy (SIRT) and immunotherapy.

BACKGROUND: Immunotherapy represents a promising option for treatment of hepatocellular carcinoma (HCC) in cirrhotic patients but its efficacy is currently inconsistent and unpredictable. Locoregional therapies inducing immunogenic cell death, such as transarterial chemoembolization (TACE) or selective internal radiation therapy (SIRT), have the potential to act synergistically with immunotherapy. For the development of new approaches combining locoregional treatments with immunotherapy, a better understanding of the respective effects of TACE and SIRT on recruitment and activation of immune cells in HCC is needed. To address this question, we compared intra-tumor immune infiltrates in resected HCC after preoperative treatment with TACE or SIRT. METHODS: Data fromr patients undergoing partial hepatectomy for HCC, without preoperative treatment (SURG, n = 32), after preoperative TACE (TACE, n = 16), or preoperative SIRT (n = 12) were analyzed. Clinicopathological factors, tumor-infiltrating lymphocytes (TILs), CD4+ and CD8+ T cells, and granzyme B (GZB) expression in resected HCC, and postoperative overall and progression-free survival were compared between the three groups. RESULTS: Clinicopathological and surgical characteristics were similar in the three groups. A significant increase in TILs, CD4+ and CD8+ T cells, and GZB expression was observed in resected HCC in SIRT as compared to TACE and SURG groups. No difference in immune infiltrates was observed between TACE and SURG patients. Within the SIRT group, the dose of irradiation affected the type of immune infiltrate. A significantly higher ratio of CD3+ cells was observed in the peri-tumoral area in patients receiving < 100 Gy, whereas a higher ratio of intra-tumoral CD4+ cells was observed in patients receiving > 100 Gy. Postoperative outcomes were similar in all groups. Irrespective of the preoperative treatment, the type and extent of immune infiltrates did not influence postoperative survival. CONCLUSIONS: SIRT significantly promotes recruitment/activation of intra-tumor effector-type immune cells compared to TACE or no preoperative treatment. These results suggest that SIRT is a better candidate than TACE to be combined with immunotherapy for treatment of HCC. Evaluation of the optimal doses for SIRT for producing an immunogenic effect and the type of immunotherapy to be used require further evaluation in prospective studies.

Age-related changes in the BACH2 and PRDM1 genes in lymphocytes from healthy donors and chronic lymphocytic leukemia patients.

BACKGROUND: Age-related genetic changes in lymphocyte subsets are not currently well documented. BACH2 is a transcription factor that plays an important role in immune-mediated homeostasis by tightly regulating PRDM1 expression in both B-cells and T-cells. BACH2 gene expression is highly sensitive to DNA damage in aged mice. This concept led us to investigate the variation in BACH2 and also PRDM1 expression in major lymphocyte subsets with age. METHODS: Lymphocyte subsets from 60 healthy donors, aged from 20 to 90 years, and 41 untreated chronic lymphocytic leukemia patients were studied. BACH2 and PRDM1 gene expression was analyzed by real-time quantitative PCR. BACH2 gene expression was correlated with its protein expression. Lymphocyte apoptosis was evaluated after intracellular oxidative stress-inducing etoposide treatment of T and B cells. RESULTS: Our analysis shows BACH2 mRNA downregulation with age in healthy donor CD4+, CD8+ T-cells and CD19+ B-cells. Decreased BACH2 expression was also correlated with an age-related reduction in CD8 + CD28+ T-cells. We found a strong correlation between age-related BACH2 downregulation and decreased CD4+ T-cell and CD19+ B-cell apoptosis. PRDM1, as expected, was significantly upregulated in CD4+ T-cells, CD8+ T-cells and CD19+ B-cells, and inversely correlated with BACH2. A comparison of untreated chronic lymphocytic leukemia patients with age-matched healthy donors reveals that BACH2 mRNA expression was further reduced in CD4+ T-cells, CD8+ T-cells and leukemic-B cells. PRDM1 gene expression was consequently significantly upregulated in CD4+ and CD8+ T-cells in chronic lymphocytic leukemia patients but not in their leukemic B-cells. CONCLUSION: Overall, our data suggest that BACH2 and PRDM1 genes are significantly correlated with age in human immune cells and may be involved in immunosenescence.

FOXP1 is a regulator of quiescence in healthy human CD4+ T cells and is constitutively repressed in T cells from patients with lymphoproliferative disorders.

The forkhead box P1 (FOXP1) transcription factor has been shown to regulate the generation and maintenance of quiescent naïve murine T cells. In humans, FOXP1 expression has been correlated with overall survival in patients with peripheral T-cell lymphoma (PTCL), although its regulatory role in T-cell function is currently unknown. We found that FOXP1 is normally expressed in all human leukocyte subpopulations. Focusing on primary human CD4+ T cells, we show that nuclear expression of FOXP1 predominates in naïve cells with significant downregulation detected in memory cells from blood and tonsils. FOXP1 is repressed following in vitro T-cell activation of naïve T cells, and later re-established in memory CD4+ T cells, albeit at lower levels. DNA methylation analysis revealed that epigenetic mechanisms participate in regulating the human FOXP1 gene. ShRNA-mediated FOXP1 repression induces CD4+ T cells to enter the cell cycle, acquire memory-like markers and upregulate helper T-cell differentiation genes. In patients with lymphoproliferative disorders, FOXP1 expression is constitutionally repressed in the clonal T cells in parallel with overexpression of helper T-cell differentiation genes. Collectively, these data identify FOXP1 as an essential transcriptional regulator for primary human CD4+ T cells and suggest its potential important role in the development of PTCL.

Reliability of tumor-infiltrating lymphocyte and tertiary lymphoid structure assessment in human breast cancer.

The presence of tumor-infiltrating lymphocytes (TIL), reflecting host immune activity, is frequently correlated with better clinical outcomes, particularly in HER2-positive and triple-negative breast cancer. Recent findings suggest that organization of immune infiltrates in tertiary lymphoid structures also has a beneficial effect on survival. This study investigated inter- and intra-observer variation in TIL assessment using conventional hematoxylin-eosin versus immunohistochemical staining to identify immune cells. Global, intratumoral, and stromal TIL, as well as tertiary lymphoid structures were scored independently by experienced pathologists on full-face tumor sections (n=124). The fidelity of scoring infiltrates in core biopsies compared to surgical specimens, and pathological assessment compared to quantitative digital analysis was also evaluated. The inter-observer concordance correlation coefficient was 0.80 for global, 0.72 for intratumoral, and 0.71 for stromal TIL, while the intra-observer concordance correlation coefficient was 0.90 for global, 0.77 for intratumoral, and 0.89 for stromal TIL using immunohistochemical stains. Correlations were lower with hematoxylin-eosin stains, particularly for intratumoral TIL, while global scores had the highest concordance correlation coefficients. Our study concluded that tertiary lymphoid structures are accurately and consistently scored using immunohistochemical but not hematoxylin-eosin stains. A strong association was observed between TIL in core biopsies and surgical samples (R2=0.74) but this did not extend to tertiary lymphoid structures (R2=0.26). TIL scored by pathologists and digital analysis were correlated but our analysis reveals a constant bias between these methods. These data challenge current criteria for TIL and tertiary lymphoid structure assessment in breast cancer and recommend that how pathologists evaluate immune infiltrates be reexamined for future studies.

CD5 promotes IL-10 production in chronic lymphocytic leukemia B cells through STAT3 and NFAT2 activation.

B lymphocytes from chronic lymphocytic leukemia (CLL) display some CD5 transcripts for CD5 containing the known exon 1 (E1A) and other CD5 transcripts containing the new exon 1 (E1B). These malignant B cells, as well as B cell lines transfected with cDNA for E1A-cd5 or with cDNA for E1B-cd5 produce IL-10, raising the possibility that CD5 participates in the secretion of IL-10. We identified transcription factors involved in this production in CD5(+) B lymphocytes from CLL patients and in E1A-cd5-transfected or E1B-cd5-transfected Jok cells. STAT3 is activated via phosphorylation of serine 727 but also NFAT2 through its translocation into the nucleus. Chromatin immunoprecipitation experiments confirmed the role of STAT3 and allowed the discovery of a role for NFAT2 in IL-10 production. Both transcription factors bind not only to the enhancer of the Il-10 gene but also to the promoter of the Il-5 and Il-13 genes. Furthermore, transfection of B cell lines with E1A-cd5 or E1B-cd5 established that activation of STAT3 and NFAT2 is regulated by CD5. The same holds true for the production of IL-10, IL-5, and IL-13 and the expression of the receptors for these cytokines. This interpretation was confirmed by two experiments. In the first, downregulation of CD5 by small interfering RNAs lowered the production of IL-10. In the second experiment, transfection of the GFP-NFAT2 gene into B lymphocytes induced nuclear translocation of NFAT2 in CD5(+) but not in CD5(-) B cells. Thus, CD5 expression is associated with NFAT2 activity (and mildly STAT3 activity), indicating that CD5 controls IL-10 secretion.

Deciphering the maturation of tertiary lymphoid structures in cancer and inflammatory diseases of the digestive tract using imaging mass cytometry.

Persistent inflammation can promote the development of tertiary lymphoid structures (TLS) within tissues resembling secondary lymphoid organs (SLO) such as lymph nodes (LN). The composition of TLS across different organs and diseases could be of pathophysiological and medical interest. In this work, we compared TLS to SLO in cancers of the digestive tract and in inflammatory bowel diseases. Colorectal and gastric tissues with different inflammatory diseases and cancers from the department of pathology of CHU Brest were analyzed based on 39 markers using imaging mass cytometry (IMC). Unsupervised and supervised clustering analyses of IMC images were used to compare SLO and TLS. Unsupervised analyses tended to group TLS per patient but not per disease. Supervised analyses of IMC images revealed that LN had a more organized structure than TLS and non-encapsulated SLO Peyer's patches. TLS followed a maturation spectrum with close correlations between germinal center (GC) markers' evolution. The correlations between organizational and functional markers made relevant the previously proposed TLS division into three stages: lymphoid-aggregates (LA) (CD20+CD21-CD23-) had neither organization nor GC functionality, non-GC TLS (CD20+CD21+CD23-) were organized but lacked GC's functionality and GC-like TLS (CD20+CD21+CD23+) had GC's organization and functionality. This architectural and functional maturation grading of TLS pointed to differences across diseases. TLS architectural and functional maturation grading is accessible with few markers allowing future diagnostic, prognostic, and predictive studies on the value of TLS grading, quantification and location within pathological tissues in cancers and inflammatory diseases.

Immune-checkpoint inhibitor use in patients with cancer and pre-existing autoimmune diseases.

Immune-checkpoint inhibitors (ICIs) have dramatically changed the management of advanced cancers. Designed to enhance the antitumour immune response, they can also cause off-target immune-related adverse events (irAEs), which are sometimes severe. Although the efficacy of ICIs suggests that they could have wide-ranging benefits, clinical trials of the drugs have so far excluded patients with pre-existing autoimmune disease. However, evidence is accumulating with regard to the use of ICIs in this 'at-risk' population, with retrospective data suggesting that they have an acceptable safety profile, but that there is a risk of disease flare or other irAE occurrence. The management of immunosuppressive drugs at ICI initiation in patients with autoimmune disease (or later in instances of disease flare or irAE) remains a question of particular interest in clinical practice, in which there is always a search for the balance between protecting against autoimmunity and ensuring a good tumour response. Although temporary use of immunosuppressants seems safe, prolonged use or use at ICI initiation might hamper the antitumour immune response, prompting clinicians to use the minimal efficient immunosuppressive regimen. However, a new paradigm is emerging, in which inhibitors of TNF or IL-6 could have synergistic effects with ICIs on tumour response, while also preventing severe irAEs. If confirmed, this 'decoupling' effect on toxicity and efficacy could change therapeutic practice in this field. Knowledge of the current use of ICIs in patients with pre-existing autoimmune disease, particularly with regard to the use of immunosuppressive drugs and/or biologic DMARDs, can help to guide clinical practice.

A Rare Case of Hepatic Vanishing Bile Duct Syndrome Occurring after Combination Therapy with Nivolumab and Cabozantinib in a Patient with Renal Carcinoma.

Tyrosine kinase inhibitors (TKIs) and immune checkpoint inhibitors (ICIs) significantly improve the outcomes of patients with advanced clear cell renal cell carcinoma (ccRCC); however, high-grade toxicities can occur, particularly during combination therapy. Herein, we report a patient with advanced metastatic ccRCC, who developed grade 4 cholestasis during combined therapy with nivolumab and cabozantinib. After the exclusion of common disorders associated with cholestasis and a failure of corticosteroids (CS), a liver biopsy was performed that demonstrated severe ductopenia. Consequently, a diagnosis of vanishing bile duct syndrome related to TKI and ICI administration was made, resulting in CS discontinuation and ursodeoxycholic acid administration. After a 7-month follow-up, liver tests had returned to normal values. Immunological studies revealed that our patient had developed robust T-cells and macrophages infiltrates in his lung metastasis, as well as in skin and liver tissues at the onset of toxicities. At the same time, peripheral blood immunophenotyping revealed significant changes in T-cell subsets, suggesting their potential role in the pathophysiology of the disease.

Low-Dose Nivolumab with or without Ipilimumab as Adjuvant Therapy Following the Resection of Melanoma Metastases: A Sequential Dual Cohort Phase II Clinical Trial.

BACKGROUND: Optimal dosing and duration of adjuvant treatment with PD-1 and CTLA-4 immune checkpoint inhibitors have not been established. Prior to their regulatory approval we investigated a low-dose regimen of nivolumab with or without ipilimumab in a sequential dual-cohort phase II clinical trial. METHODS: Following the complete resection of melanoma metastases, patients were treated with a single fixed dose of ipilimumab (50 mg) plus 4 bi-weekly fixed doses of nivolumab (10 mg) (cohort-1), or nivolumab for 1 year (10 mg fixed dose, Q2w x9, followed by Q8w x4) (cohort-2). Twelve-months relapse-free survival (RFS) served as the primary endpoint. RESULTS: After a median follow-up of 235 weeks for cohort-1 (34 patients), and 190 weeks for cohort-2 (21 patients), the 12-months RFS-rate was, respectively, 55.9% (95% CI, 39-72), and 85.7% (95% CI, 70-100). Treatment-related adverse events occurred in 27 (79%), and 18 (86%) patients, with 3 (9%), and 1 (5%) grade 3 adverse events in cohort-1 and -2, respectively. Immunohistochemical quantification of intra- and peritumoral CD3+ T cells and CD20+ B cells, but not PD-1/PD-L1 staining, correlated significantly with RFS. CONCLUSIONS: One year of adjuvant low-dose nivolumab could be an effective and economically advantageous alternative for standard dosing, at the condition of further confirmation in a larger patient cohort. A shorter low-dose nivolumab plus ipilimumab regimen seems inferior and less tolerable.

IL-6 modulates CD5 expression in B cells from patients with lupus by regulating DNA methylation.

B lymphocytes from patients with systemic lupus erythematosus (SLE) are characterized by reduced expression levels of membrane CD5. Recent studies from our laboratory have revealed that the level of membrane CD5 is determined by the relative level of two alternative CD5 isoforms; CD5-E1A, which is expressed on the membrane, and CD5-E1B, which is retained in the cytoplasm. Using bisulfite sequencing and methylation-sensitive endonuclease assays we show that the promoter for the alternative CD5-E1B isoform is demethylated in B cells from patients with SLE but not in healthy controls. We go on to show that differential methylation is more pronounced following BCR engagement. As a result of this demethylation, CD5-E1B mRNA is transcribed at the expense of CD5-E1A mRNA transcription. We provide further evidence that production of high IL-6 levels by SLE B cells abrogates the ability of SLE B cells to induce DNA methyl transferase (DNMT1) and then to methylate DNA, an effect that is reversed in the presence of a blocking Ab to the IL-6 receptor. The pattern of demethylation of CpG islands in the CD5-E1B promoter in SLE B cells is similar to those in B cells from healthy controls stimulated in the presence of IL-6, or treated with the methylation inhibitor PD98059. The study reveals that engagement of the BCR with constitutive IL-6 down-regulates the level of membrane CD5, which negatively regulates BCR signaling, in SLE B cells. This altered signaling could, in turn, promote the activation and expansion of autoreactive B cells in SLE patients.

DNA methylation and B-cell autoreactivity.

Although not exclusive, mounting evidence supports the fact that DNA methylation at CpG dinucleotides controls B-cell development and the progressive eliminati or inactivation of autoreactive B cell. Indeed, the expression of different B ce specific factors, including Pax5, rearrangement of the B-cell receptor (BCR) and cytokine production are tightly controlled by DNA methylation. Among normal B cells, the autoreactive CD5+ B cell sub-population presents a reduced capacity to methylate its DNA that leads to the expression of normally repressed genes, such as the human endogenous retrovirus (HERV). In systemic lupus erythematosus (SLE) patients, the archetype ofautoimmune disease, autoreactive B cells are characterized by their inability to induce DNA methylation that prolongs their survival. Finally, treating B cells with demethylating drugs increased their autoreactivity. Altogether this suggests that a deeper comprehension ofDNA methylation in B cells may offer opportunities to develop new therapeutics to control autoreactive B cells.

Persistent anti-tumor response in cancer patients experiencing pneumonitis related to immune checkpoint blockade.

Background: Immunotherapy in the form of immune checkpoint inhibition (ICI) is now well established as acornerstone for treating many advanced malignancies. Nevertheless, as the number of indications for checkpoint inhibitors increases, so does the risk of immune-related adverse events (irAEs).Methods: We report two patient cases who, after being treated by an anti-programmed cell death 1 (PD-1), presented with grade III dyspnea due to pneumonitis.Discussion: Immunotherapy was discontinued and the patients required treatment with systemic corticosteroids. At the time of writing, both patients are still in complete response (CR), more than 1year beyond immunotherapy discontinuation. We discuss our cases with regard to recent literature reports on immune-related pneumonitis and persistence of response beyond discontinuation.

Fluorescent Multiplex Immunohistochemistry Coupled With Other State-Of-The-Art Techniques to Systematically Characterize the Tumor Immune Microenvironment.

Our expanding knowledge of the interactions between tumor cells and their microenvironment has helped to revolutionize cancer treatments, including the more recent development of immunotherapies. Immune cells are an important component of the tumor microenvironment that influence progression and treatment responses, particularly to the new immunotherapies. Technological advances that help to decipher the complexity and diversity of the tumor immune microenvironment (TIME) are increasingly used in translational research and biomarker studies. Current techniques that facilitate TIME evaluation include flow cytometry, multiplex bead-based immunoassays, chromogenic immunohistochemistry (IHC), fluorescent multiplex IHC, immunofluorescence, and spatial transcriptomics. This article offers an overview of our representative data, discusses the application of each approach to studies of the TIME, including their advantages and challenges, and reviews the potential clinical applications. Flow cytometry and chromogenic and fluorescent multiplex IHC were used to immune profile a HER2+ breast cancer, illustrating some points. Spatial transcriptomic analysis of a luminal B breast tumor demonstrated that important additional insight can be gained from this new technique. Finally, the development of a multiplex panel to identify proliferating B cells, Tfh, and Tfr cells on the same tissue section demonstrates their co-localization in tertiary lymphoid structures.

Functional Th1-oriented T follicular helper cells that infiltrate human breast cancer promote effective adaptive immunity.

We previously demonstrated that tumor-infiltrating lymphocytes (TIL) in human breast cancer sometimes form organized tertiary lymphoid structures (TLS) characterized by CXCL13-producing T follicular helper (Tfh) cells. The present study found that CD4+ Tfh TIL, CD8+ TIL, and TIL-B, colocalizing in TLS, all express the CXCL13 receptor CXCR5. An ex vivo functional assay determined that only activated, functional Th1-oriented Tfh TIL (PD-1hiICOSint phenotype) provide help for immunoglobulin and IFN-γ production. A functional Tfh TIL presence signals an active TLS, characterized by humoral (immunoglobulins, Ki-67+ TIL-B in active germinal centers) and cytotoxic (GZMB+CD8+ and GZMB+CD68+ TIL plus Th1 gene expression) immune responses. Analysis of active versus inactive TLS in untreated patients revealed that the former are associated with positive clinical outcomes. TLS also contain functional T follicular regulatory (Tfr) TIL, which are characterized by a CD25+CXCR5+GARP+FOXP3+ phenotype and a demethylated FOXP3 gene. Functional Tfr inhibited functional Tfh activities via a glycoprotein A repetitions predominant (GARP)-associated TGF-ß-dependent mechanism. The activity of tumor-associated TLS was dictated by the relative balance between functional Tfh TIL and functional Tfr TIL. These data provide mechanistic insight into TLS processes orchestrated by functional Th1-oriented Tfh TIL, including TIL-B and CD8+ TIL activation and immunological memory generation. Tfh TIL, regulated by functional Tfr TIL, are an expected key target of PD-1/PD-L1 blockade.

Downregulation of the FTO m6A RNA demethylase promotes EMT-mediated progression of epithelial tumors and sensitivity to Wnt inhibitors.

Post-transcriptional modifications of RNA constitute an emerging regulatory layer of gene expression. The demethylase fat mass- and obesity-associated protein (FTO), an eraser of N6-methyladenosine (m6A), has been shown to play a role in cancer, but its contribution to tumor progression and the underlying mechanisms remain unclear. Here, we report widespread FTO downregulation in epithelial cancers associated with increased invasion, metastasis and worse clinical outcome. Both in vitro and in vivo, FTO silencing promotes cancer growth, cell motility and invasion. In human-derived tumor xenografts (PDXs), FTO pharmacological inhibition favors tumorigenesis. Mechanistically, we demonstrate that FTO depletion elicits an epithelial-to-mesenchymal transition (EMT) program through increased m6A and altered 3'-end processing of key mRNAs along the Wnt signaling cascade. Accordingly, FTO knockdown acts via EMT to sensitize mouse xenografts to Wnt inhibition. We thus identify FTO as a key regulator, across epithelial cancers, of Wnt-triggered EMT and tumor progression and reveal a therapeutically exploitable vulnerability of FTO-low tumors.

Selection of the alternative exon 1 from the cd5 gene down-regulates membrane level of the protein in B lymphocytes.

The human cd5 gene has two alternative exons 1: exon 1A (E1A) which encodes the full-length (FL) CD5 protein and exon 1B (E1B) which encodes a truncated (TR) isoform. The FL variant of CD5 protein is translocated to the plasma membrane, while its TR variant is retained in the cytoplasm. Because there is an inverse relationship between the levels of FL-CD5 and TR-CD5 in B cells, we have addressed the issue of how the selection of exon 1 is determined. In leukemic B cells, DNA methyltransferase (DNMT)1-induced methylation of E1B prevents its transcription. Furthermore, the level of mRNA for DNMT1 correlates inversely with that of mRNA for CD5-E1B. However, suppression of E1B transcription is incomplete, and some molecules of TR-CD5 continue to be synthesized. Bortezomid-induced inhibition of the proteasome establishes that these TR-CD5 molecules are cleared through the ubiquitin-proteasome pathway. Transfection of CD5 mutants into COS-1 cells locates the ubiquitin-binding site at the second destruction box of the extracellular region of CD5. Activation of the B cells by anti-IgM, Staphylococcus aureus Cowan I (SAC), or PMA up-regulates DNMT1, and thereby CD5-E1A mRNA at the expense of CD5-E1B mRNA. Aberrant synthesis of TR-CD5 is thus offset by balanced degradation of excessive protein. Dysregulation of these mechanisms reduces the expression level of membrane CD5, and thereby diminishes the threshold of the response by cells expressing CD5.

Inhibition of RANK signaling in breast cancer induces an anti-tumor immune response orchestrated by CD8+ T cells.

Most breast cancers exhibit low immune infiltration and are unresponsive to immunotherapy. We hypothesized that inhibition of the receptor activator of nuclear factor-κB (RANK) signaling pathway may enhance immune activation. Here we report that loss of RANK signaling in mouse tumor cells increases leukocytes, lymphocytes, and CD8+ T cells, and reduces macrophage and neutrophil infiltration. CD8+ T cells mediate the attenuated tumor phenotype observed upon RANK loss, whereas neutrophils, supported by RANK-expressing tumor cells, induce immunosuppression. RANKL inhibition increases the anti-tumor effect of immunotherapies in breast cancer through a tumor cell mediated effect. Comparably, pre-operative single-agent denosumab in premenopausal early-stage breast cancer patients from the Phase-II D-BEYOND clinical trial (NCT01864798) is well tolerated, inhibits RANK pathway and increases tumor infiltrating lymphocytes and CD8+ T cells. Higher RANK signaling activation in tumors and serum RANKL levels at baseline predict these immune-modulatory effects. No changes in tumor cell proliferation (primary endpoint) or other secondary endpoints are observed. Overall, our preclinical and clinical findings reveal that tumor cells exploit RANK pathway as a mechanism to evade immune surveillance and support the use of RANK pathway inhibitors to prime luminal breast cancer for immunotherapy.

Tumor-Derived Thymic Stromal Lymphopoietin Expands Bone Marrow B-cell Precursors in Circulation to Support Metastasis.

Immature B cells in the bone marrow emigrate into the spleen during adult lymphopoiesis. Here, we report that emigration is shifted to earlier B-cell stages in mice with orthotopic breast cancer, spontaneous ovarian cancer, and possibly in human breast carcinoma. Using mouse and human bone marrow aspirates and mouse models challenged with highly metastatic 4T1 breast cancer cells, we demonstrated that this was the result of secretion of thymic stromal lymphopoietin (TSLP) by cancer cells. First, TSLP downregulated surface expression of bone marrow (BM) retention receptors CXCR4 and VLA4 in B-cell precursors, increasing their motility and, presumably, emigration. Then, TSLP supported peripheral survival and proliferation of BM B-cell precursors such as pre-B-like cells. 4T1 cancer cells used the increased pool of circulating pre-B-like cells to generate metastasis-supporting regulatory B cells. As such, the loss of TSLP expression in cancer cells alone or TSLPR deficiency in B cells blocked both accumulation of pre-B-like cells in circulation and cancer metastasis, implying that the pre-B cell-TSLP axis can be an attractive therapeutic target. SIGNIFICANCE: Cancer cells induce premature emigration of B-cell precursors from the bone marrow to generate regulatory B cells.

Tumor infiltrating B-cells signal functional humoral immune responses in breast cancer.

Tumor-infiltrating B-cells (TIL-B) in breast cancer (BC) have previously been associated with improved clinical outcomes; however, their role(s) in tumor immunity is not currently well known. This study confirms and extends the correlation between higher TIL-B densities and positive outcomes through an analysis of HER2-positive and triple-negative BC patients from the BIG 02-98 clinical trial (10yr mean follow-up). Fresh tissue analyses identify an increase in TIL-B density in untreated primary BC compared to normal breast tissues, which is associated with global, CD4+ and CD8+ TIL, higher tumor grades, higher proliferation and hormone receptor negativity. All B-cell differentiation stages are detectable but significant increases in memory TIL-B are consistently present. BC with higher infiltrates are specifically characterized by germinal center TIL-B, which in turn are correlated with TFH TIL and antibody-secreting TIL-B principally located in tertiary lymphoid structures. Some TIL-B also interact directly with tumor cells. Functional analyses reveal TIL-B are responsive to BCR stimulation ex vivo, express activation markers and produce cytokines and immunoglobulins despite reduced expression of the antigen-presenting molecules HLA-DR and CD40. Overall, these data support the concept that ongoing humoral immune responses are generated by TIL-B and help to generate effective anti-tumor immunity at the tumor site.