Correlation of RANK and RANKL with mammographic density in primary breast cancer patients.

PURPOSE: The receptor activator of nuclear factor kappa B (RANK) and its ligand (RANKL) have been shown to promote proliferation of the breast and breast carcinogenesis. The objective of this analysis was to investigate whether tumor-specific RANK and RANKL expression in patients with primary breast cancer is associated with high percentage mammographic density (PMD), which is a known breast cancer risk factor. METHODS: Immunohistochemical staining of RANK and RANKL was performed in tissue microarrays (TMAs) from primary breast cancer samples of the Bavarian Breast Cancer Cases and Controls (BBCC) study. For RANK and RANKL expression, histochemical scores (H scores) with a cut-off value of > 0 vs 0 were established. PMD was measured in the contralateral, non-diseased breast. Linear regression models with PMD as outcome were calculated using common predictors of PMD (age at breast cancer diagnosis, body mass index (BMI) and parity) and RANK and RANKL H scores. Additionally, Spearman rank correlations (ρ) between PMD and RANK and RANKL H score were performed. RESULTS: In the final cohort of 412 patients, breast cancer-specific RANK and RANKL expression was not associated with PMD (P = 0.68). There was no correlation between PMD and RANK H score (Spearman's ρ = 0.01, P = 0.87) or RANKL H score (Spearman's ρ = 0.04, P = 0.41). RANK expression was highest in triple-negative tumors, followed by HER2-positive, luminal B-like and luminal A-like tumors, while no subtype-specific expression of RANKL was found. CONCLUSION: Results do not provide evidence for an association of RANK and RANKL expression in primary breast cancer with PMD.

RANK and RANKL Expression in Tumors of Patients with Early Breast Cancer.

Introduction: The receptor activator of nuclear factor-κB (RANK) pathway was associated with the pathogenesis of breast cancer. Several studies attempted to link the RANK/RANKL pathway to prognosis; however, with inconsistent outcomes. We aimed to further contribute to the knowledge about RANK/RANKL as prognostic factors in breast cancer. Within this study, protein expression of RANK and its ligand, RANKL, in the tumor tissue was analyzed in association with disease-free survival (DFS) and overall survival (OS) in a study cohort of patients with early breast cancer. Patients and Methods: 607 samples of female primary and early breast cancer patients from the Bavarian Breast Cancer Cases and Controls Study were analyzed to correlate the RANK and RANKL expression with DFS and OS. Therefore, expression was quantified using immunohistochemical staining of a tissue microarray. H-scores were determined with the cut-off value of 8.5 for RANK and 0 for RANKL expression, respectively. Results: RANK and RANKL immunohistochemistry were assessed by H-score. Both biomarkers did not correlate (ρ = -0.04). According to molecular subtypes, triple-negative tumors and HER2-positive tumors showed a higher number of RANK-positive tumors (H-score ≥ 8.5), however, no subtype-specific expression of RANKL could be detected. Higher RANKL expression tended to correlate with a better prognosis. However, RANK and RANKL expression could not be identified as statistically significant prognostic factors within the study cohort. Conclusions: Tumor-specific RANK and RANKL expressions are not applicable as prognostic factors for DFS and OS, but might be associated with subtype-specific breast cancer progression.

NMDAR antagonists suppress tumor progression by regulating tumor-associated macrophages.

Neurotransmitter receptors are increasingly recognized to play important roles in anti-tumor immunity. The expression of the ion channel N-methyl-D-aspartate receptor (NMDAR) on macrophages was reported, but the role of NMDAR on macrophages in the tumor microenvironment (TME) remains unknown. Here, we show that the activation of NMDAR triggered calcium influx and reactive oxygen species production, which fueled immunosuppressive activities in tumor-associated macrophages (TAMs) in the hepatocellular sarcoma and fibrosarcoma tumor settings. NMDAR antagonists, MK-801, memantine, and magnesium, effectively suppressed these processes in TAMs. Single-cell RNA sequencing analysis revealed that blocking NMDAR functionally and metabolically altered TAM phenotypes, such that they could better promote T cell- and Natural killer (NK) cell-mediated anti-tumor immunity. Treatment with NMDAR antagonists in combination with anti-PD-1 antibody led to the elimination of the majority of established preclinical liver tumors. Thus, our study uncovered an unknown role for NMDAR in regulating macrophages in the TME of hepatocellular sarcoma and provided a rationale for targeting NMDAR for tumor immunotherapy.

Inhibition of CD39 unleashes macrophage antibody-dependent cellular phagocytosis against B-cell lymphoma.

Redirection of tumor-associated macrophages to eliminate tumor cells holds great promise for overcoming therapeutic resistance to rituximab and other antibody drugs. Here, we determined the expression of ectonucleotidases CD39 and CD73 in diffuse large B-cell lymphoma (DLBCL), and examined the impact of extracellular ATP (eATP) metabolism on macrophage-mediated anti-lymphoma immunity. Immunostaining of tissue microarray samples showed that CD39 (the ecto-enzyme for eATP hydrolysis) was highly expressed in tumors with the non-germinal center B-cell-like (non-GCB) subtype, and to a lesser extent tumors with the GCB subtype. By contrast, the expression of CD73 (the ecto-enzyme for adenosine generation) was undetectable in tumor cells. Pharmacological blockade of CD39 prevented eATP degradation and enhanced engulfment of antibody-coated lymphoma cells by macrophages in a P2X7 receptor-dependent manner, indicating that eATP fueled antibody-dependent cellular phagocytosis (ADCP) activity. Importantly, inhibition of CD39 augmented in vivo anti-lymphoma effects by therapeutic antibodies including rituximab and daratumumab. Furthermore, the addition of a CD39 inhibitor to anti-CD20 and anti-CD47 combination therapy significantly improved survival in a disseminated model of aggressive B-cell lymphoma, supporting the benefit of dual targeting CD39-mediated eATP hydrolysis and CD47-mediated "don't eat me" signal. Together, preventing eATP degradation may be a potential approach to unleash macrophage-mediated anti-lymphoma immunity.

CD155 on Tumor Cells Drives Resistance to Immunotherapy by Inducing the Degradation of the Activating Receptor CD226 in CD8+ T Cells.

The activating receptor CD226 is expressed on lymphocytes, monocytes, and platelets and promotes anti-tumor immunity in pre-clinical models. Here, we examined the role of CD226 in the function of tumor-infiltrating lymphocytes (TILs) and resistance to immunotherapy. In murine tumors, a large proportion of CD8+ TILs had decreased surface expression of CD226 and exhibited features of dysfunction, whereas CD226hi TILs were highly functional. This correlation was seen also in TILs isolated from HNSCC patients. Mutation of CD226 at tyrosine 319 (Y319) led to increased CD226 surface expression, enhanced anti-tumor immunity and improved efficacy of immune checkpoint blockade (ICB). Mechanistically, tumor-derived CD155, the ligand for CD226, initiated phosphorylation of Y319 by Src kinases, thereby enabling ubiquitination of CD226 by CBL-B, internalization, and proteasomal degradation. In pre-treatment samples from melanoma patients, CD226+CD8+ T cells correlated with improved progression-free survival following ICB. Our findings argue for the development of therapies aimed at maintaining the expression of CD226.

The NK cell granule protein NKG7 regulates cytotoxic granule exocytosis and inflammation.

Immune-modulating therapies have revolutionized the treatment of chronic diseases, particularly cancer. However, their success is restricted and there is a need to identify new therapeutic targets. Here, we show that natural killer cell granule protein 7 (NKG7) is a regulator of lymphocyte granule exocytosis and downstream inflammation in a broad range of diseases. NKG7 expressed by CD4+ and CD8+ T cells played key roles in promoting inflammation during visceral leishmaniasis and malaria-two important parasitic diseases. Additionally, NKG7 expressed by natural killer cells was critical for controlling cancer initiation, growth and metastasis. NKG7 function in natural killer and CD8+ T cells was linked with their ability to regulate the translocation of CD107a to the cell surface and kill cellular targets, while NKG7 also had a major impact on CD4+ T cell activation following infection. Thus, we report a novel therapeutic target expressed on a range of immune cells with functions in different immune responses.

Tumor CD155 Expression Is Associated with Resistance to Anti-PD1 Immunotherapy in Metastatic Melanoma.

PURPOSE: Resistance to anti-PD1-based immune checkpoint blockade (ICB) remains a problem for the treatment of metastatic melanoma. Tumor cells as well as host myeloid cells can express the immune checkpoint ligand CD155 to regulate immune cell function. However, the effect of tumor CD155 on the immune context of human melanoma has not been well described. This observational study characterizes tumor CD155 ligand expression by metastatic melanoma tumors and correlates results with differences in immune cell features and response to ICB. EXPERIMENTAL DESIGN: Pretreatment tumor specimens, from 155 patients with metastatic melanoma treated with ICB and from 50 patients treated with BRAF/MEK-directed targeted therapy, were assessed for CD155 expression by IHC. Intratumor T-cell features were analyzed using multiplex-immunohistofluorescence for CD8, PD1, and SOX10. Correlations were made between CD155 tumor level and bulk tumor RNA sequencing results, as well as clinical RECIST response and progression-free survival. RESULTS: High pretreatment CD155 tumor levels correlated with high parenchymal PD1+CD8+/CD8+ T-cell ratios (PD1tR) and poor response to anti-PD1 therapy. In PDL1 negative tumors, high CD155 tumor expression was associated with patients who had poor response to combination anti-PD1/CTLA4 therapy. CONCLUSIONS: Our findings are the first to suggest that tumor CD155 supports an increase in the fraction of PD1+CD8+ T cells in anti-PD1 refractory melanoma tumors and, further, that targeting the CD155 pathway might improve response to anti-PD1 therapy for patients with metastatic melanoma.

Pharmacodynamics of Pre-Operative PD1 checkpoint blockade and receptor activator of NFkB ligand (RANKL) inhibition in non-small cell lung cancer (NSCLC): study protocol for a multicentre, open-label, phase 1B/2, translational trial (POPCORN).

BACKGROUND: Neoadjuvant immunotherapy targeting immune checkpoint programmed death-1 (PD-1) is under investigation in various tumour settings including non-small-cell lung cancer (NSCLC). Preclinical models demonstrate the superior power of the immunotherapy provided in a neoadjuvant (pre-operative) compared with an adjuvant (post-operative) setting to eradicate metastatic disease and induce long-lasting antigen-specific immunity. Novel effective immunotherapy combinations are widely sought in the oncology field, targeting non-redundant mechanisms of immune evasion. A promising combination partner with anti-PD1 in NSCLC is denosumab, a monoclonal antibody blocking receptor activator of NF-κB ligand (RANKL). In preclinical cancer models and in a large retrospective case series in NSCLC, anti-cancer activity has been reported for the combination of immune checkpoint inhibition (ICI) and denosumab. Furthermore, clinical trials of ICI and denosumab are underway in advanced melanoma and clear-cell renal cell carcinoma. However, the mechanism of action of combination anti-PD1 and anti-RANKL is poorly defined. METHODS: This open-label multicentre trial will randomise by minimisation 30 patients with resectable stage IA (primary > 2 cm) to IIIA NSCLC to a neoadjuvant treatment regime of either two doses of nivolumab (3 mg/kg every 2 weeks) or two doses of nivolumab (same regimen) plus denosumab (120 mg every 2 weeks, following nivolumab). Each treatment arm is of equal size and will be approximately balanced with respect to histology (squamous vs. non-squamous) and clinical stage (I-II vs. IIIA). All patients will receive surgery for their tumour 2 weeks after the final dose of neoadjuvant therapy. The primary outcome will be translational research to define the tumour-immune correlates of combination therapy compared with monotherapy. Key secondary outcomes will include a comparison of rates of the following between each arm: toxicity, response (pathological and radiological), and microscopically complete resection. DISCUSSION: The POPCORN study provides a unique platform for translational research to determine the mechanism of action of a novel proposed combination immunotherapy for cancer. TRIAL REGISTRATION: Prospectively registered on Australian New Zealand Clinical Trials Registry (ACTRN12618001121257) on 06/07/2018.

Dual targeting of RANKL and PD-1 with a bispecific antibody improves anti-tumor immunity.

OBJECTIVES: The addition of RANKL/RANK blockade to immune checkpoint inhibitors (ICIs) such as anti-PD-1/PD-L1 and anti-CTLA4 antibodies is associated with increased anti-tumor immunity in mice. Recent retrospective clinical studies in patients with advanced melanoma and lung cancer suggest the addition of anti-RANKL antibody to ICI increases the overall response rate relative to ICI treatment alone. Based on this rationale, we developed a novel bispecific antibody (BsAb) co-targeting RANKL and PD-1. METHODS: We characterized target binding and functional activity of the anti-RANKL/PD-1 BsAb in cell-based assays. Anti-tumor activity was confirmed in experimental lung metastasis models and in mice with established subcutaneously transplanted tumors. RESULTS: The anti-RANKL/PD-1 BsAb retained binding to both RANKL and PD-1 and blocked the interaction with respective counter-structures RANK and PD-L1. The inhibitory effect of anti-RANKL/PD-1 BsAb was confirmed by demonstrating a complete block of RANKL-dependent osteoclast formation. Monotherapy activity of anti-RANKL/PD-1 BsAb was observed in anti-PD-1 resistant tumors and, when combined with anti-CTLA-4 mAb, increased anti-tumor responses. An equivalent or superior anti-tumor response was observed with the anti-RANKL/PD-1 BsAb compared with the combination of parental anti-RANKL plus anti-PD-1 antibodies depending upon the tumor model. DISCUSSION: Mechanistically, the anti-tumor activity of anti-RANKL/PD-1 BsAb required CD8+T cells, host PD-1 and IFNγ. Targeting RANKL and PD-1 simultaneously within the tumor microenvironment (TME) improved anti-tumor efficacy compared with combination of two separate mAbs. CONCLUSION: In summary, the bispecific anti-RANKL/PD-1 antibody demonstrates potent tumor growth inhibition in settings of ICI resistance and represents a novel modality for clinical development in advanced cancer.

CD96 Is an Immune Checkpoint That Regulates CD8+ T-cell Antitumor Function.

CD96 is a novel target for cancer immunotherapy shown to regulate NK cell effector function and metastasis. Here, we demonstrated that blocking CD96 suppressed primary tumor growth in a number of experimental mouse tumor models in a CD8+ T cell-dependent manner. DNAM-1/CD226, Batf3, IL12p35, and IFNγ were also critical, and CD96-deficient CD8+ T cells promoted greater tumor control than CD96-sufficient CD8+ T cells. The antitumor activity of anti-CD96 therapy was independent of Fc-mediated effector function and was more effective in dual combination with blockade of a number of immune checkpoints, including PD-1, PD-L1, TIGIT, and CTLA-4. We consistently observed coexpression of PD-1 with CD96 on CD8+ T lymphocytes in tumor-infiltrating leukocytes both in mouse and human cancers using mRNA analysis, flow cytometry, and multiplex IHF. The combination of anti-CD96 with anti-PD-1 increased the percentage of IFNγ-expressing CD8+ T lymphocytes. Addition of anti-CD96 to anti-PD-1 and anti-TIGIT resulted in superior antitumor responses, regardless of the ability of the anti-TIGIT isotype to engage FcR. The optimal triple combination was also dependent upon CD8+ T cells and IFNγ. Overall, these data demonstrate that CD96 is an immune checkpoint on CD8+ T cells and that blocking CD96 in combination with other immune-checkpoint inhibitors is a strategy to enhance T-cell activity and suppress tumor growth.

The immune checkpoint CD96 defines a distinct lymphocyte phenotype and is highly expressed on tumor-infiltrating T cells.

CD96 has recently been shown to be a potent immune checkpoint molecule in mice, but a similar role in humans is not known. In this study, we provide a detailed map of CD96 expression across human lymphocyte lineages, the kinetics of CD96 regulation on T-cell activation and co-expression with other conventional and emerging immune checkpoint molecules. We show that CD96 is predominantly expressed by T cells and has a unique lymphocyte expression profile. CD96high T cells exhibited distinct effector functions on activation. Of note, CD96 expression was highly correlated with T-cell markers in primary and metastatic human tumors and was elevated on antigen-experienced T cells and tumor-infiltrating lymphocytes. Collectively, these data demonstrate that CD96 may be a promising immune checkpoint to enhance T-cell function against human cancer and infectious disease.

An observational study of concomitant immunotherapies and denosumab in patients with advanced melanoma or lung cancer.

After a case report of profound clinical response in a melanoma patient following treatment with an immune checkpoint inhibitor (ICI) and RANK-ligand inhibitor denosumab, we identified similar patients from electronic health records (EHR) and described patient characteristics and outcomes. This 2017 observational study used Flatiron Health's EHR database from ~255 US cancer clinics. Included were advanced melanoma or non-small-cell lung cancer (NSCLC) patients who received denosumab within 30 days of CTLA-4 (ipilimumab) or PD1 (pembrolizumab, nivolumab) inhibitors start with a minimum of 6 months of follow up. Real-world tumor response (rwTR) was analyzed for scans available up to 30 days after concomitant therapy. Preclinical experiments evaluated sequencing of ICI, denosumab vs monotherapy or control. Melanoma (n = 66) patients received concomitant denosumab/ICI for a mean 4.0 months, 3.1 months for NSCLC (n = 241). Two-thirds of patients had best rwTR evaluable (complete [CR], partial response [PR], stable disease [SD], or disease progression [PD]). Longer mean duration of concomitant exposure was associated with overall response rate (ORR; CR+PR) in melanoma (p = 0.0172), NSCLC (p < .0001), and combined cohorts (p < .0001). The disease control rate (ORR plus SD) was 56% amongst melanoma patients and 58% amongst NSCLC patients. Longer concomitant therapy was associated with increased overall survival, primarily in NSCLC (p < .0001). Preclinical data suggest that ICI initiated before or at same time as denosumab was optimal. Results provide proof-of-concept that rwTR is associated with concomitant denosumab/ICI. Crude survival analyses supported the association of concomitant therapy and improved outcomes outside of clinical trials and warrant comparative study.

Roles of the RANKL-RANK axis in antitumour immunity - implications for therapy.

Recognizing that the transformative effects of immunotherapy are currently limited to a minority of patients with cancer, research efforts are increasingly focused on expanding and enhancing clinical responses by combining immunotherapies; the repurposing of existing drugs is an attractive approach, given their well-characterized safety and pharmacokinetic profiles. Receptor activator of nuclear factor-κB (RANK) and the RANK ligand (RANKL) were initially described in the context of T cell-dendritic cell interactions; however, the discovery of an obligate role of RANK signalling in osteoclastogenesis led to the development of the anti-RANKL antibody denosumab for antiresorptive indications, including bone metastases. Randomized clinical trials and post-marketing surveillance studies have established the acceptable safety profile of denosumab. More recently, several case reports involving patients with advanced-stage melanoma have described remarkable responses following concurrent treatment with denosumab and immune-checkpoint inhibitors. Randomized trials assessing similar combinations in patients with melanoma or renal cell carcinoma are now underway. Herein, we discuss the hallmark clinical trials of denosumab in light of possible immunological effects of this agent. We highlight the role of immune cells as sources of RANK and RANKL in the tumour microenvironment and review data on RANKL inhibition in mouse models of cancer. Finally, we describe hypothetical immune-related mechanisms of action, which could be assessed in clinical trials of immune-checkpoint inhibitors and denosumab in patients with cancer.

Receptor activator of NF-κB (RANK)-mediated induction of metastatic spread and association with poor prognosis in renal cell carcinoma.

BACKGROUND: Inhibition of the receptor activator of NF-κB ligand (RANKL) has become a standard of care supportive treatment to prevent skeletal related events in cancer patients. Moreover, RANKL inhibition has been implicated with better survival outcome in lung cancer, while RANKL expression induces tumor progression and metastatic spread in vivo in breast cancer. Whether RANK/RANKL may have an impact on the pathogenesis of clear cell renal cell carcinoma (ccRCC) is currently unknown. PATIENTS AND METHODS: A retrospective tissue micro array (TMA)-study was carried out determining the expression of RANK/RANKL in primary tumors of 306 ccRCC patients. Additionally, 24 ccRCC cell lines were employed for in vitro analyses of the RANK/RANKL axis including cell proliferation, migration and anchorage independent growth. RESULTS: RANK (+) vs. RANK (-) tumors had both worse cancer specific survival (CSS) (6.3 vs. 1.3 years; p < 0.001) and recurrence free survival (RFS) (9.9 vs. 5.8 years; p < 0.001). RANK (+) (HR 2.21; p < 0.001) was an independent prognostic factor for CSS and RFS (HR 4.98; p < 0.001). RANKL treatment resulted in increased proliferation, soft agar growth, and colony formation of RANK (+) RCC cell lines, which could be reversed by treatment with an NF-κB inhibitor and with a combination of osteoprotegrin and RANKL in vitro. CONCLUSIONS: RANK is expressed in ccRCC tissue, correlates with clinicopathological features, survival outcome, and when stimulated with RANKL can induce ccRCC progression in vitro. Consequently, RANKL inhibition combined with standard of care treatment may be a promising approach to improve ccRCC patient's survival.

TIGIT immune checkpoint blockade restores CD8+ T-cell immunity against multiple myeloma.

Immune-based therapies hold promise for the treatment of multiple myeloma (MM), but so far, immune checkpoint blockade targeting programmed cell death protein 1 has not proven effective as single agent in this disease. T-cell immunoglobulin and ITIM domains (TIGIT) is another immune checkpoint receptor known to negatively regulate T-cell functions. In this study, we investigated the therapeutic potential of TIGIT blockade to unleash immune responses against MM. We observed that, in both mice and humans, MM progression was associated with high levels of TIGIT expression on CD8+ T cells. TIGIT+ CD8+ T cells from MM patients exhibited a dysfunctional phenotype characterized by decreased proliferation and inability to produce cytokines in response to anti-CD3/CD28/CD2 or myeloma antigen stimulation. Moreover, when challenged with Vk*MYC mouse MM cells, TIGIT-deficient mice showed decreased serum monoclonal immunoglobulin protein levels associated with reduced tumor burden and prolonged survival, indicating that TIGIT limits antimyeloma immune responses. Importantly, blocking TIGIT using monoclonal antibodies increased the effector function of MM patient CD8+ T cells and suppressed MM development. Altogether our data provide evidence for an immune-inhibitory role of TIGIT in MM and support the development of TIGIT-blocking strategies for the treatment of MM patients.

Deficiency of host CD96 and PD-1 or TIGIT enhances tumor immunity without significantly compromising immune homeostasis.

Multiple non-redundant immunosuppressive pathways co-exist in the tumor microenvironment and their co-targeting can increase clinical responses. Indeed, concurrent blockade of CTLA-4 and PD-1 in patients with advanced melanoma increased clinical responses over monotherapy alone although the frequency and severity of immune related adverse events (irAEs) also increased. Nevertheless, a substantial number of patients still display an innate resistance phenotype and are unresponsive to current approved immunotherapies even when utilized in combination. In this study, we generated Pdcd1-/-CD96-/- and Tigit-/-CD96-/- mice to investigate how loss of CD96 in combination with PD-1 or TIGIT impacts on immune homeostasis and hence the potential of inducing immune related toxicities following co-targeting of these pairs of receptors. The ability of Pdcd1-/-CD96-/- and Tigit-/-CD96-/- mice to suppress primary tumor growth was also assessed using the MC38 colon carcinoma and SM1WT1 BRAF-mutated melanoma tumor models. Both Pdcd1-/-CD96-/- or Tigit-/-CD96-/- mice displayed no overt perturbations in immune homeostasis over what was previously reported with Pdcd1-/- or Tigit-/- mice even when aged for 22 months. Interestingly, increased suppression of subcutaneous tumor growth and complete responses was seen in Pdcd1-/-CD96-/- mice compared to Pdcd1-/- or CD96-/- mice depending upon the tumor model. In contrast, in these models, growth suppression in Tigit-/-CD96-/- were similar to Tigit-/- or CD96-/- . This enhanced anti-tumor efficacy of Pdcd1-/-CD96-/- appeared to be due to favorable changes in the ratio of CD8+ T cells to T regulatory cells or CD11b+GR-1hi myeloid cells in the tumor microenvironment. Co-targeting CD96 and PD-1 may increase anti-tumor immunity over targeting PD-1 alone and potentially not induce serious immune-related toxicities and thus appears a promising strategy for clinical development.

RANKL blockade improves efficacy of PD1-PD-L1 blockade or dual PD1-PD-L1 and CTLA4 blockade in mouse models of cancer.

Receptor activator of NF-κB ligand (RANKL) and its receptor RANK, are members of the tumor necrosis factor and receptor superfamilies, respectively. Antibodies targeting RANKL have recently been evaluated in combination with anti-CTLA4 in case reports of human melanoma and mouse models of cancer. However, the efficacy of anti-RANKL in combination with antibodies targeting other immune checkpoint receptors such as PD1 has not been reported. In this study, we demonstrated that blockade of RANKL improves anti-metastatic activity of antibodies targeting PD1/PD-L1 and improves subcutaneous growth suppression in mouse models of melanoma, prostate and colon cancer. Suppression of experimental lung metastasis following combination anti-RANKL with anti-PD1 requires NK cells and IFN-γ, whereas subcutaneous tumor growth suppression with this combination therapy is attenuated in the absence of T cells and IFN-γ. Furthermore, addition of anti-RANKL to anti-PD1 and anti-CTLA4 resulted in superior anti-tumor responses, irrespective of the ability of anti-CTLA4 isotype to engage activating FcR, and concurrent or delayed RANKL blockade was most effective. Early-during-treatment assessment reveals this triple combination therapy compared to dual anti-PD1 and anti-CTLA4 combination therapy further increased the proportion of tumor-infiltrating CD4+ and CD8+ T cells that can produce both IFN-γ and TNF. Finally, RANKL expression appears to identify tumor-specific CD8+ T cells expressing higher levels of PD1 which can be modulated by anti-PD1. These data set the scene for clinical evaluation of denosumab use in patients receiving contemporary immune checkpoint blockade.

CD96 targeted antibodies need not block CD96-CD155 interactions to promote NK cell anti-metastatic activity.

CD96 is a transmembrane glycoprotein Ig superfamily receptor, expressed on various T cell subsets and NK cells, that interacts with nectin and nectin-like proteins, including CD155/polio virus receptor (PVR). Here, we have compared three rat anti-mouse CD96 mAbs, including two that block CD96-CD155 (3.3 and 6A6) and one that does not block CD96-CD155 (8B10). Using flow cytometry, we demonstrated that both mAbs 3.3 and 6A6 bind to the first Ig domain of mouse CD96 and compete with CD155 binding, while mAb 8B10 binds to the second Ig domain and does not block CD155. While Fc isotype was irrelevant concerning the anti-metastatic activity of 3.3 mAb, in four different experimental metastases models and one spontaneous metastasis model, the relative order of anti-metastatic potency was 6A6 > 3.3 > 8B10. The metastatic burden control of all of the anti-CD96 clones was highly dependent on NK cells and IFN-γ. Consistent with its inability to block CD96-CD155 interactions, 8B10 retained anti-metastatic activity in CD155-deficient mice, whereas 3.3 and 6A6 lost potency in CD155-deficient mice. Furthermore, 8B10 retained most of its anti-metastatic activity in IL-12p35-deficient mice whereas the activity of 3.3 and 6A6 were partially lost. All three mAbs were inactive in CD226-deficient mice. Altogether, these data demonstrate anti-CD96 need not block CD96-CD155 interactions (ie. immune checkpoint blockade) to promote NK cell anti-metastatic activity.