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. CD96 high 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 diseas

POSEIDON Trial Phase 1b Results: Safety, Efficacy and Circulating Tumor DNA Response of the Beta Isoform-Sparing PI3K Inhibitor Taselisib (GDC-0032) Combined with Tamoxifen in Hormone Receptor Positive Metastatic Breast Cancer Patients.

PURPOSE: The strategy of combining endocrine therapy with PI3K-mTOR inhibition has shown promise in estrogen receptor (ER)-positive breast cancer, but new agents and combinations with a better therapeutic index are urgently needed. Taselisib is a potent, selective, beta-isoform-sparing PI3 kinase inhibitor. PATIENTS AND METHODS: 30 patients with ER-positive, metastatic breast cancer who had failed prior endocrine therapy were treated with escalating doses of taselisib (2 or 4 mg in an intermittent or continuous schedule) combined with tamoxifen 20 mg once daily in this phase 1b study using a "rolling six" design. RESULTS: Taselisib combined with tamoxifen was generally well tolerated, with treatment-emergent adverse events as expected for this class of drugs, including diarrhea (13 patients, 43%), mucositis (10 patients, 33%), and hyperglycemia (8 patients, 27%). No dose-limiting toxicities were observed. Objective responses were seen in 6 of 25 patients with RECIST-measurable disease (ORR 24%). Median time to disease progression was 3.7 months. Twelve of 30 patients (40%) had disease control for 6 months or more. Circulating tumor (ct)DNA studies using next-generation tagged amplicon sequencing identified early indications of treatment response and mechanistically relevant correlates of clinical drug resistance (e.g., mutations in KRAS, ERBB2) in some patients. CONCLUSIONS: Taselisib can be safely combined with tamoxifen at the recommended phase 2 dose of 4 mg given once daily on a continuous schedule. Preliminary evidence of antitumor activity was seen in both PIK3CA mutant and wild-type cancers. The randomized phase 2 part of POSEIDON (testing tamoxifen plus taselisib or placebo) is currently recruiting

First Sagittarius A* Event Horizon Telescope Results. VIII. Physical Interpretation of the Polarized Ring

In a companion paper, we present the first spatially resolved polarized image of Sagittarius A* on event horizon scales, captured using the Event Horizon Telescope, a global very long baseline interferometric array operating at a wavelength of 1.3 mm. Here we interpret this image using both simple analytic models and numerical general relativistic magnetohydrodynamic (GRMHD) simulations. The large spatially resolved linear polarization fraction (24%–28%, peaking at ∼40%) is the most stringent constraint on parameter space, disfavoring models that are too Faraday depolarized. Similar to our studies of M87*, polarimetric constraints reinforce a preference for GRMHD models with dynamically important magnetic fields. Although the spiral morphology of the polarization pattern is known to constrain the spin and inclination angle, the time-variable rotation measure (RM) of Sgr A* (equivalent to ≈46° ± 12° rotation at 228 GHz) limits its present utility as a constraint. If we attribute the RM to internal Faraday rotation, then the motion of accreting material is inferred to be counterclockwise, contrary to inferences based on historical polarized flares, and no model satisfies all polarimetric and total intensity constraints. On the other hand, if we attribute the mean RM to an external Faraday screen, then the motion of accreting material is inferred to be clockwise, and one model passes all applied total intensity and polarimetric constraints: a model with strong magnetic fields, a spin parameter of 0.94, and an inclination of 150°. We discuss how future 345 GHz and dynamical imaging will mitigate our present uncertainties and provide additional constraints on the black hole and its accretion flow

TIGIT and CD96: new checkpoint receptor targets for cancer immunotherapy

While therapies targeting the co-inhibitory or immune checkpoint receptors PD-1 and CTLA-4 have shown remarkable success in many cancers, not all patients benefit from these therapies. This has catalyzed enormous interest in the targeting of other immune checkpoint receptors. In this regard, TIGIT and CD96 have recently entered the limelight as novel immune checkpoint receptor targets. TIGIT and CD96 together with the co-stimulatory receptor CD226 form a pathway that is analogous to the CD28/CTLA-4 pathway, in which shared ligands and differential receptor:ligand affinities fine-tune the immune response. Although the roles of TIGIT and CD96 as immune checkpoint receptors in T cell and natural killer cell biology are just beginning to be uncovered, accumulating data support the targeting of these receptors for improving anti-tumor immune responses. A clear understanding of the immune cell populations regulated by TIGIT and CD96 is key to the design of immunotherapies that target these receptors in combination with other existing immune checkpoint blockade therapies

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 CD8T 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

RANK Overexpression in Transgenic Mice with Mouse Mammary Tumor Virus Promoter-Controlled RANK Increases Proliferation and Impairs Alveolar Differentiation in the Mammary Epithelia and Disrupts Lumen Formation in Cultured Epithelial Acini

RANK and RANKL, the key regulators of osteoclast differentiation and activation, also play an important role in the control of proliferation and differentiation of mammary epithelial cells during pregnancy. Here, we show that RANK protein expression is strictly regulated in a spatial and temporal manner during mammary gland development. RANK overexpression under the control of the mouse mammary tumor virus (MMTV) promoter in a transgenic mouse model results in increased mammary epithelial cell proliferation during pregnancy, impaired differentiation of lobulo-alveolar structures, decreased expression of the milk proteins β-casein and whey acidic protein, and deficient lactation. We also show that treatment of three-dimensional in vitro cultures of primary mammary cells from MMTV-RANK mice with RANKL results in increased proliferation and decreased apoptosis in the luminal area, resulting in bigger acini with filled lumens. Taken together, these results suggest that signaling through RANK not only promotes proliferation but also inhibits the terminal differentiation of mammary epithelial cells. Moreover, the increased proliferation and survival observed in a three-dimensional culture system suggests a role for aberrant RANK signaling during breast tumorigenesis

Molecular pathways: targeting CD96 and TIGIT for cancer immunotherapy

The receptors CD96 and TIGIT are expressed on the surface of T and NK cells and recent studies suggest both play important inhibitory roles in immune function. CD96 has been shown to modulate immune cell activity in mice, with Cd96-/- mice displaying hypersensitive NK cell responses to immune challenge and significant tumor resistance. TIGIT overexpression has been shown to reduce NK cell-mediated cytotoxicity. TIGIT is also upregulated on T-cells during cancer and chronic viral infection, with expression associated with effector T-cell exhaustion and increased Treg suppression. The counterbalance between the putative inhibitory CD96, TIGIT receptors and the activating receptor, CD226, offers unique strategies for immuno-oncology drug development. Blocking CD96 or TIGIT with monoclonal antibodies (mAbs) has been shown to improve tumor control in mice, in particular when used in combination with PD-1/PD-L1 blockade. These results have highlighted these pathways as promising new targets for immune modulation. This review will examine the rationale behind targeting CD96 and TIGIT and discuss the potential approaches in translating these preclinical findings into novel clinical agents

Data from: Aberrant activation of the RANK signaling receptor induces murine salivary gland tumors

Unlike cancers of related exocrine tissues such as the mammary and prostate gland, diagnosis and treatment of aggressive salivary gland malignancies have not markedly advanced in decades. Effective clinical management of malignant salivary gland cancers is undercut by our limited knowledge concerning the key molecular signals that underpin the etiopathogenesis of this rare and heterogeneous head and neck cancer. Without knowledge of the critical signals that drive salivary gland tumorigenesis, tumor vulnerabilities cannot be exploited that allow for targeted molecular therapies. This knowledge insufficiency is further exacerbated by a paucity of preclinical mouse models (as compared to other cancer fields) with which to both study salivary gland pathobiology and test novel intervention strategies. Using a mouse transgenic approach, we demonstrate that deregulation of the Receptor Activator of NFkB Ligand (RANKL)/RANK signaling axis results in rapid tumor development in all three major salivary glands. In line with its established role in other exocrine gland cancers (i.e., breast cancer), the RANKL/RANK signaling axis elicits an aggressive salivary gland tumor phenotype both at the histologic and molecular level. Despite the ability of this cytokine signaling axis to drive advanced stage disease within a short latency period, early blockade of RANKL/RANK signaling markedly attenuates the development of malignant salivary gland neoplasms. Together, our findings have uncovered a tumorigenic role for RANKL/RANK in the salivary gland and suggest that targeting this pathway may represent a novel therapeutic intervention approach in the prevention and/or treatment of this understudied head and neck cancer

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\ua0days of CTLA-4 (ipilimumab) or PD1 (pembrolizumab, nivolumab) inhibitors start with a minimum of 6\ua0months of follow up. Real-world tumor response (rwTR) was analyzed for scans available up to 30\ua0days after concomitant therapy. Preclinical experiments evaluated sequencing of ICI, denosumab vs monotherapy or control. Melanoma (n\ua0=\ua066) patients received concomitant denosumab/ICI for a mean 4.0\ua0months, 3.1\ua0months for NSCLC (n\ua0=\ua0241). 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\ua0=\ua00.0172), NSCLC (p\ua

RANK and RANK ligand expression in primary human osteosarcoma

Receptor activator of nuclear factor kappa-B ligand (RANKL) is an essential mediator of osteoclast formation, function and survival. In patients with solid tumor metastasis to the bone, targeting the bone microenvironment by inhibition of RANKL using denosumab, a fully human monoclonal antibody (mAb) specific to RANKL, has been demonstrated to prevent tumor-induced osteolysis and subsequent skeletal complications. Recently, a prominent functional role for the RANKL pathway has emerged in the primary bone tumor giant cell tumor of bone (GCTB). Expression of both RANKL and RANK is extremely high in GCTB tumors and denosumab treatment was associated with tumor regression and reduced tumor-associated bone lysis in GCTB patients. In order to address the potential role of the RANKL pathway in another primary bone tumor, this study assessed human RANKL and RANK expression in human primary osteosarcoma (OS) using specific mAbs, validated and optimized for immunohistochemistry (IHC) or flow cytometry. Our results demonstrate RANKL expression was observed in the tumor element in 68% of human OS using IHC. However, the staining intensity was relatively low and only 37% (29/79) of samples exhibited≥10% RANKL positive tumor cells. RANK expression was not observed in OS tumor cells. In contrast, RANK expression was clearly observed in other cells within OS samples, including the myeloid osteoclast precursor compartment, osteoclasts and in giant osteoclast cells. The intensity and frequency of RANKL and RANK staining in OS samples were substantially less than that observed in GCTB samples. The observation that RANKL is expressed in OS cells themselves suggests that these tumors may mediate an osteoclastic response, and anti-RANKL therapy may potentially be protective against bone pathologies in OS. However, the absence of RANK expression in primary human OS cells suggests that any autocrine RANKL/RANK signaling in human OS tumor cells is not operative, and anti-RANKL therapy would not directly affect the tumor