Heterogeneous characterization of neutrophilic cells in head and neck cancers

BACKGROUND

Neutrophilic cells are among the most abundant immune populations within the head and neck tumor microenvironment (TME) and harbor multiple mechanisms of immunosuppression. Despite these important features, neutrophilic cells may be underrepresented in contemporary studies that aim to comprehensively characterize the immune landscape of the TME due to discrepancies in tissue processing and analysis techniques. Here, we review the role of pathologically activated neutrophilic cells within the TME and pitfalls of various approaches used to study their frequency and function in clinical samples.

METHODS

The literature was identified by searching PubMed for "immune landscape" and "tumor immune microenvironment" in combination with keywords describing solid tumor malignancies. Key publications that assessed the immune composition of solid tumors derived from human specimens were included. The tumor and blood processing methodologies in each study were reviewed in depth and correlated with the reported abundance of neutrophilic cells.

RESULTS

Neutrophilic cells do not survive cryopreservation, and many studies fail to identify and study neutrophilic cell populations due to cryopreservation of clinical samples for practical reasons. Additional single-cell transcriptomic studies filter out neutrophilic cells due to low transcriptional counts.

CONCLUSIONS

This report can help readers critically interpret studies aiming to comprehensively study the immune TME that fail to identify and characterize neutrophilic cells.

Quantification and Functional Studies of Neutrophilic Cells Identifies Distinct Papilloma Phenotypes

OBJECTIVES

To characterize the distribution of immune cell subsets within laryngeal papillomas and to study the function of potentially immunosuppressive neutrophilic and regulatory T cells (Tregs).

METHODS

Fresh clinical papilloma specimens were collected at the time of surgery and studied with multiparameter flow cytometry. Papilloma infiltrating neutrophilic cells and Tregs were sorted and studied functionally with ex vivo T cell suppression assays.

RESULTS

Flow cytometric analysis of fresh laryngeal papillomas samples from 18 adult patients with recurrent respiratory papillomatosis revealed patterns in immune constituency between patients. Clearly divergent phenotypes based primarily on the degree of neutrophilic and T cell infiltration were identified. Relative neutrophilic cell enrichment and T cell depletion were observed in 50% of samples and neutrophilic cell depletion and T cell enrichment were observed in the others. Greater papilloma neutrophilic cell enrichment was positively associated with the number of clinically indicated interventions required in the 12 months prior to sample collection, linking papilloma neutrophil inflammation to disease severity. Functional assays revealed the ability of both papilloma infiltrating neutrophilic and Tregs to suppress T cell function at roughly equal magnitudes, but substantially increased infiltration of neutrophilic cells compared to Tregs across samples.

CONCLUSION

Neutrophilic cells are an important contributor to immunosuppression within the respiratory papilloma microenvironment. Given these data and the association between greater neutrophilic cell infiltration and lack of clinical response to therapeutic vaccination, additional study of strategies aimed at limiting neutrophilic cell infiltration or function within papillomas is warranted.

LEVEL OF EVIDENCE

4 Laryngoscope, 2024.

Myeloid-Derived Suppressive Cell Expansion Promotes Melanoma Growth and Autoimmunity by Inhibiting CD40/IL27 Regulation in Macrophages

The relationship between cancer and autoimmunity is complex. However, the incidence of solid tumors such as melanoma has increased significantly among patients with previous or newly diagnosed systemic autoimmune disease (AID). At the same time, immune checkpoint blockade (ICB) therapy of cancer induces de novo autoinflammation and exacerbates underlying AID, even without evident antitumor responses. Recently, systemic lupus erythematosus (SLE) activity was found to drive myeloid-derived suppressor cell (MDSC) formation in patients, a known barrier to healthy immune surveillance and successful cancer immunotherapy. Cross-talk between MDSCs and macrophages generally drives immune suppressive activity in the tumor microenvironment. However, it remains unclear how peripheral pregenerated MDSC under chronic inflammatory conditions modulates global macrophage immune functions and the impact it could have on existing tumors and underlying lupus nephritis. Here we show that pathogenic expansion of SLE-generated MDSCs by melanoma drives global macrophage polarization and simultaneously impacts the severity of lupus nephritis and tumor progression in SLE-prone mice. Molecular and functional data showed that MDSCs interact with autoimmune macrophages and inhibit cell surface expression of CD40 and the production of IL27. Moreover, low CD40/IL27 signaling in tumors correlated with high tumor-associated macrophage infiltration and ICB therapy resistance both in murine and human melanoma exhibiting active IFNγ signatures. These results suggest that preventing global macrophage reprogramming induced by MDSC-mediated inhibition of CD40/IL27 signaling provides a precision melanoma immunotherapy strategy, supporting an original and advantageous approach to treat solid tumors within established autoimmune landscapes. SIGNIFICANCE: Myeloid-derived suppressor cells induce macrophage reprogramming by suppressing CD40/IL27 signaling to drive melanoma progression, simultaneously affecting underlying autoimmune disease and facilitating resistance to immunotherapy within preexisting autoimmune landscapes.

Dual PD-L1 and TGF-b blockade in patients with recurrent respiratory papillomatosis

Background

Recurrent respiratory papillomatosis (RRP) is a human papillomavirus (HPV) driven neoplastic disorder of the upper aerodigestive tract that causes significant morbidity and can lead to fatal airway obstruction. Prior clinical study demonstrated clinical benefit with the programmed death-ligand 1 (PD-L1) monoclonal antibody avelumab. Bintrafusp alfa is a bifunctional inhibitor of PD-L1 and transforming growth factor-beta (TGF-b) that has shown clinical activity in several cancer types.

Methods

We conducted a phase II clinical trial evaluating bintrafusp alfa in adults with RRP. Papilloma samples before and after treatment with bintrafusp alfa were assessed for correlates of response with multiplex immunofluorescence as well as immunological and genomic analyses. Post hoc analyses of papilloma samples before and after treatment with avelumab were assessed for comparison.

Results

Dual PD-L1/TGF-b inhibition failed to abrogate papilloma growth in most subjects and increased the frequency of clinically indicated interventions after treatment in four of eight subjects based on each subject’s own historical control. TGF-b neutralization consistently decreased pSMAD3 and p21 and increased Ki67 expression within the basal layers of papillomas, indicating that TGF-b restrained proliferation. These alterations were not observed in papillomas treated with PD-L1 blockade alone. Dual PD-L1/TGF-b inhibition did not enhance anti-HPV immunity within papillomas beyond that observed with PD-L1 blockade. Genomic alterations in TGF-b superfamily genes were infrequent in papillomas and normal mucosa but present in a significant fraction of head and neck carcinomas.

Conclusions

Intact TGF-b signaling restrains proliferation within papillomas, and the use of clinical agents that abrogate this pathway should be avoided in patients with RRP.

Trial registration numbers

NCT03707587 and NCT02859454.

Chimeric antigen receptor engineered NK cellular immunotherapy overcomes the selection of T-cell escape variant cancer cells

BACKGROUND

As heterogeneous tumors develop in the face of intact immunity, tumor cells harboring genomic or expression defects that favor evasion from T-cell detection or elimination are selected. For patients with such tumors, T cell-based immunotherapy alone infrequently results in durable tumor control.

METHODS

Here, we developed experimental models to study mechanisms of T-cell escape and demonstrated that resistance to T-cell killing can be overcome by the addition of natural killer (NK) cells engineered to express a chimeric antigen receptor (CAR) targeting programmed death ligand-1 (PD-L1).

RESULTS

In engineered models of tumor heterogeneity, PD-L1 CAR-engineered NK cells (PD-L1 t-haNKs) prevented the clonal selection of T cell-resistant tumor cells observed with T-cell treatment alone in multiple models. Treatment of heterogenous cancer cell populations with T cells resulted in interferon gamma (IFN-γ) release and subsequent upregulation of PD-L1 on tumor cells that escaped T-cell killing through defects in antigen processing and presentation, priming escape cell populations for PD-L1 dependent killing by PD-L1 t-haNKs in vitro and in vivo.

CONCLUSIONS

These results describe the underlying mechanisms governing synergistic antitumor activity between T cell-based immunotherapy that results in IFN-γ production, upregulation of PD-L1 on T-cell escape cells, and the use of PD-L1 CAR-engineered NK cells to target and eliminate resistant tumor cell populations.

Tumor control via targeting PD-L1 with chimeric antigen receptor modified NK cells

Failed T cell-based immunotherapies in the presence of genomic alterations in antigen presentations pathways may be overcome by NK cell-based immunotherapy. This approach may still be limited by the presence of immunosuppressive myeloid populations. Here, we demonstrate that NK cells (haNKs) engineered to express a PD-L1 chimeric antigen receptor (CAR) haNKs killed a panel of human and murine head and neck cancer cells at low effector-to-target ratios in a PD-L1-dependent fashion. Treatment of syngeneic tumors resulted in CD8 and PD-L1-dependent tumor rejection or growth inhibition and a reduction in myeloid cells endogenously expressing high levels of PD-L1. Treatment of xenograft tumors resulted in PD-L1-dependent tumor growth inhibition. PD-L1 CAR haNKs reduced levels of macrophages and other myeloid cells endogenously expressing high PD-L1 in peripheral blood from patients with head and neck cancer. The clinical study of PD-L1 CAR haNKs is warranted.

Abstract A15: Integrated biomarker trials to evaluate myeloid and lymphoid composition of HNSCC and solid tumors treated with pepinemab and combinations with checkpoint inhibitors

Recruitment of immunosuppressive myeloid cells into the tumor microenvironment (TME) is a critical limitation to the efficacy of immune checkpoint inhibitors (ICIs) in patients with head and neck squamous cell carcinoma (HNSCC). In preclinical models, antibody blockade of Semaphorin 4D (SEMA4D, CD100) reduced function and recruitment of immunosuppressive myeloid cells within the TME. Importantly, combinations of anti-SEMA4D with ICIs enhanced T-cell activity and tumor regression. Pepinemab, an IgG4 humanized monoclonal antibody targeting SEMA4D, is currently being evaluated in window of opportunity, integrated biomarker trials to characterize immunomodulatory effects of treatment. SEMA4D exerts multifaceted effects within the tumor microenvironment by creating a barrier at the tumor-stroma margin, restricting immune cell infiltration and promoting immunosuppressive activity of myeloid-derived cells. In preclinical in vitro and in vivo studies, blocking antibody to SEMA4D directly enhanced M1/M2 ratio and reduced both expression of chemokines that recruit MDSC and the ability of MDSC to suppress T-cell activity. SEMA4D antibody treatment simultaneously restored the ability of dendritic cells and cytotoxic T cells to infiltrate the TME and increased ratio of Teffector to Tregulatory cells. This coordinated shift from immunosuppression to tumoricidal activity complemented effects of other immunotherapies in syngeneic tumor models. At present, three biomarker-driven window of opportunity trials are recruiting patients with four resectable indications to investigate novel combinations of pepinemab with ICIs: 1) HNSCC (NCT03690986, n=36), 2) pancreatic ductal adenocarcinoma and colorectal cancer with resectable liver metastases (NCT03373188, n=32), and 3) metastatic melanoma (NCT03769155, n=36). Presurgical treatment cohorts include combinations of pepinemab with nivolumab and /or ipilimumab, single agents, or no treatment. Three to seven weeks later, surgically resected tumors are collected under the guidance of a pathologist for comparison of tumor infiltrates across treatment groups and with a predose tissue biopsy. Blood is collected for PK, PD, and additional correlative biomarker assessments. Correlative multiplex flow cytometric and immunohistochemistry panels have been established to phenotype cells in the TME and periphery; preliminary biomarker analysis will be presented. Additional objectives include evaluation of pathologic response and extension of the previously reported safety profile of pepinemab to additional ICI combination therapies. Twelve subjects, including two HNSCC patients, have been enrolled in these studies as of 01 Feb 2019. These trials will provide the first integrated clinical assessment of the use of anti-SEMA4D antibody to reprogram the TME.

Citation Format: Elizabeth E. Evans, Gregory B. Lesinski, Terrence L. Fisher, Crystal Mallow, Brian Olson, Paul E. Clavijo, John E. Leonard, Desa Rae Pastore, Ernest S. Smith, Maurice Zauderer, Clint T. Allen, Michael Lowe, Ragini Kudchadkar, Christina Wu, Conor Steuer, Nabil F. Saba. Integrated biomarker trials to evaluate myeloid and lymphoid composition of HNSCC and solid tumors treated with pepinemab and combinations with checkpoint inhibitors [abstract]. In: Proceedings of the AACR-AHNS Head and Neck Cancer Conference: Optimizing Survival and Quality of Life through Basic, Clinical, and Translational Research; 2019 Apr 29-30; Austin, TX. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(12_Suppl_2):Abstract nr A15.

ASTX660, an antagonist of cIAP1/2 and XIAP, increases antigen processing machinery and can enhance radiation-induced immunogenic cell death in preclinical models of head and neck cancer

Inhibitor of apoptosis protein (IAP) antagonists have shown activity in preclinical models of head and neck squamous cell carcinoma (HNSCC), and work across several cancer types has demonstrated diverse immune stimulatory effects including enhancement of T cell, NK cell, and dendritic cell function. However, tumor-cell-intrinsic mechanisms for this immune upregulation have been largely unexplored. In this study, we show that ASTX660, an antagonist of cIAP1/2 and XIAP, induces expression of immunogenic cell death (ICD) markers in sensitive HNSCC cell lines in vitro. Experiments in syngeneic mouse models of HNSCC showed that ASTX660 can also enhance radiation-induced ICD in vivo. On a functional level, ASTX660 also enhanced killing of multiple murine cell lines by cytotoxic tumor-infiltrating lymphocytes, and when combined with XRT, stimulated clonal expansion of antigen-specific T lymphocytes and expression of MHC class I on the surface of tumor cells. Flow cytometry experiments in several human HNSCC cell lines showed that MHC class I (HLA-A,B,C) was reliably upregulated in response to ASTX660 + TNFα, while increases in other antigen processing machinery (APM) components were variable among different cell lines. These findings suggest that ASTX660 may enhance anti-tumor immunity both by promoting ICD and by enhancing antigen processing and presentation.

Inhibition of MDSC Trafficking with SX-682, a CXCR1/2 Inhibitor, Enhances NK-Cell Immunotherapy in Head and Neck Cancer Models

PURPOSE

Natural killer (NK)-cell-based immunotherapy may overcome obstacles to effective T-cell-based immunotherapy such as the presence of genomic alterations in IFN response genes and antigen presentation machinery. All immunotherapy approaches may be abrogated by the presence of an immunosuppressive tumor microenvironment present in many solid tumor types, including head and neck squamous cell carcinoma (HNSCC). Here, we studied the role of myeloid-derived suppressor cells (MDSC) in suppressing NK-cell function in HNSCC.

EXPERIMENTAL DESIGN

The ability of peripheral and tumor-infiltrating MDSC from mice bearing murine oral cancer 2 (MOC2) non-T-cell-inflamed tumors and from patients with HNSCC to suppress NK-cell function was studied with real-time impedance and ELISpot assays. The therapeutic efficacy of SX-682, a small-molecule inhibitor of CXCR1 and CXCR2, was assessed in combination with adoptively transferred NK cells.

RESULTS

Mice bearing MOC2 tumors pathologically accumulate peripheral CXCR2⁺ neutrophilic-MDSC (PMN-MDSC) that traffic into tumors and suppress NK-cell function through TGFβ and production of H₂O₂. Inhibition of MDSC trafficking with orally bioavailable SX-682 significantly abrogated tumor MDSC accumulation and enhanced the tumor infiltration, activation, and therapeutic efficacy of adoptively transferred murine NK cells. Patients with HNSCC harbor significant levels of circulating and tumor-infiltrating CXCR1/2⁺ CD15⁺ PMN-MDSC and CD14⁺ monocytic-MDSC. Tumor MDSC exhibited greater immunosuppression than those in circulation. HNSCC tumor MDSC immunosuppression was mediated by multiple, independent, cell-specific mechanisms including TGFβ and nitric oxide.

CONCLUSIONS

The clinical study of CXCR1/2 inhibitors in combination with adoptively transferred NK cells is warranted.

Neoadjuvant PD-1 Immune Checkpoint Blockade Reverses Functional Immunodominance among Tumor Antigen-Specific T Cells

PURPOSE

Surgical resection of primary tumor with regional lymphadenectomy remains the treatment of choice for patients with advanced human papillomavirus-negative head and neck squamous cell carcinoma. However, even when pathologic disease-free margins can be achieved, locoregional and/or distant disease relapse remains high. Perioperative immunotherapy may improve outcomes, but mechanistic data supporting the use of neoadjuvant or adjuvant treatment clinically are sparse.

EXPERIMENTAL DESIGN

Two syngeneic models of oral cavity carcinoma with defined T-cell antigens were treated with programmed death receptor 1 (PD-1) mAb before or after surgical resection of primary tumors, and antigen-specific T-cell responses were explored with functional and in vivo challenge assays.

RESULTS

We demonstrated that functional immunodominance developed among T cells targeting multiple independent tumor antigens. T cells specific for subdominant antigens expressed greater levels of PD-1. Neoadjuvant, but not adjuvant, PD-1 immune checkpoint blockade broke immunodominance and induced T-cell responses to dominant and subdominant antigens. Using tumors lacking the immunodominant antigen as a model of antigen escape, neoadjuvant PD-1 immune checkpoint blockade induced effector T-cell immunity against tumor cells lacking immunodominant but retaining subdominant antigen. When combined with complete surgical excision, neoadjuvant PD-1 immune checkpoint blockade led to formation of immunologic memory capable of preventing engraftment of tumors lacking the immunodominant but retaining subdominant antigen.

CONCLUSIONS

Together, these results implicate PD-1 expression by T cells in the mechanism of functional immunodominance among independent T-cell clones within a progressing tumor and support the use of neoadjuvant PD-1 immune checkpoint blockade in patients with surgically resectable carcinomas.

Enhancing direct cytotoxicity and response to immune checkpoint blockade following ionizing radiation with Wee1 kinase inhibition

Tumor cells activate the G2/M cell cycle checkpoint in response to ionizing radiation (IR) and effector immune cell-derived granzyme B to facilitate repair and survival. Wee1 kinase inhibition reverses the ability of tumor cells to pause at G2/M. Here, we hypothesized that AZD1775, a small molecule inhibitor of Wee1 kinase, could sensitize tumor cells to IR and T-lymphocyte killing and improve responses to combination IR and programmed death (PD)-axis immune checkpoint blockade (ICB). Multiple models of head and neck carcinoma, lung carcinoma and melanoma were used in vitro and in vivo to explore this hypothesis. AZD1775 reversed G2/M cell cycle checkpoint activation following IR, inducing cell death. Combination IR and AZD1775 induced accumulation of DNA damage in M-phase cells and was rescued with nucleoside supplementation, indicating mitotic catastrophe. Combination treatment enhanced control of syngeneic MOC1 tumors in vivo, and on-target effects of systemic AZD1775 could be localized with targeted IR. Combination treatment enhanced granzyme B-dependent T-lymphocyte killing through reversal of additive G2/M cell cycle block induced by IR and granzyme B. Combination IR and AZ1775-enhanced CD8⁺ cell-dependent MOC1 tumor growth control and rate of complete rejection of established tumors in the setting of PD-axis ICB. Functional assays demonstrated increased tumor antigen-specific immune responses in sorted T-lymphocytes. The combination of IR and AZD1775 not only lead to enhanced tumor-specific cytotoxicity, it also enhanced susceptibility to T-lymphocyte killing and responses to PD-axis ICB. These data provide the pre-clinical rationale for the combination of these therapies in the clinical trial setting.

Abstract 1545: Altered myeloid and lymphoid composition of tumor microenvironment following anti-SEMA4D and immune checkpoint combination therapies

Anti-semaphorin 4D (SEMA4D, CD100) blocking antibody promotes immune infiltration, reduces immunosuppressive myeloid cells, and enhances T cell activity and tumor growth inhibition in combination with various immunotherapies in preclinical animal models. Clinical trials of immune checkpoint inhibitors (ICI) in combination with pepinemab (VX15/2503), humanized anti-SEMA4D antibody, are currently underway in several cancer indications. SEMA4D exerts multi-faceted effects within the tumor microenvironment by creating a barrier at the tumor-stroma margin to restrict immune cell infiltration and promote immunosuppressive activity of myeloid-derived cells. Blocking antibody to SEMA4D directly enhanced M1/M2 ratio and reduced both expression of chemokines that recruit MDSC and the ability of MDSC to suppress T cell activity. Antibody blockade simultaneously restored the ability of dendritic cells and cytotoxic T cells to infiltrate the TME, increasing ratio of Teffector to Tregulatory cells, in syngeneic tumor models. Importantly, anti-SEMA4D MAb enhanced the activity of co-administered immunotherapies, including antibodies to PD1, CTLA-4, and LAG3, epigenetic modulators, and additional novel immunomodulatory combinations in murine breast, colon, head and neck, and melanoma tumor models. New data will describe development and application of methods to assess immune phenotype and biomarkers in translational and clinical studies. These include flow cytometry and whole slide scans of multiplex IHC panels to examine MDSC, M1/M2 macrophage, monocytes, activated DC, B cells, exhausted, activated and stem-like populations of T cells in clinical samples. Expression of SEMA4D and its receptor PlexinB1 were also evaluated in spatial context and cellular co-localization. In summary, SEMA4D represents a novel target to regulate immune infiltration and mesenchymal suppression, sources of resistance to current immunotherapies. Pepinemab treatment was well tolerated in a Phase I oncology trial (NCT01313065) and is currently being evaluated as single agent or in ICI combinations in: (i) a Phase 1b/2a combination trial of pepinemab with avelumab in ICI naïve or ICI refractory NSCLC (CLASSICAL-Lung) (NCT03268057); (ii) a phase 1 combination trial of pepinemab with nivolumab or ipilimumab in melanoma patients who have progressed on any anti-PD-1/PD-L1 (NCT03425461); (iii) a neoadjuvant integrated biomarker trial in patients with metastatic colorectal, pancreatic (NCT03373188) and head and neck (NCT03690986) cancers treated with pepinemab in combination with nivolumab or ipilimumab; and (iv) a Phase 1/2 trial of pepinemab in children with solid tumors and children and young adults with osteosarcoma (NCT03320330). Clinical trials will evaluate safety, tolerability, efficacy, and biological endpoints, including immunophenotyping tumors and blood.

Citation Format: Elizabeth E. Evans, Terrence L. Fisher, Holm Bussler, Crystal Mallow, Christine Reilly, Sebold Torno, Desa Rae Pastore, Maria Scrivens, Alan Howell, Leslie Balch, John E. Leonard, Clint Allen, Paul E. Clavijo, Gregory Lesinski, Christina Wu, Conor Steuer, Nabil F. Saba, Brian Olson, Siwen Hu-Lieskovan, Antoni Ribas, Emily G. Greengard, Ernest S. Smith, Maurice Zauderer. Altered myeloid and lymphoid composition of tumor microenvironment following anti-SEMA4D and immune checkpoint combination therapies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1545.

Abstract 3206: Host immunity following near infrared photoimmunotherapy is enhanced with PD-1 checkpoint blockade to eradicate established highly antigenic tumors

Near infrared photoimmunotherapy (NIR-PIT) is a newly developed cancer treatment that employs a targeted monoclonal antibody-photo-absorber conjugate (APC). Following antibody localization of the APC to a tumor cell surface antigen, NIR light is used to induce highly selective cytolysis. Extensive pre-clinical evidence demonstrates that NIR-PIT is effective at inducing tumor cell lysis using a number of different antibody-APC conjugates and NIR-PIT targeting EGFR with a cetuximab-APC conjugate has shown promising results in phase 2 clinical evaluation for the treatment of recurrent head and neck squamous cell carcinoma. NIR-PIT induces rapid, necrotic cell death that yields innate immune ligands that activate dendritic cells, consistent with immunogenic cell death. Yet, NIR-PIT treatment of syngeneic tumors in wild-type mice has mostly failed to induce durable regression of established tumors, suggesting the presence of one or more mechanisms of resistance to formation of meaningful anti-tumor immunity. In this study, we hypothesized that NIR-PIT could induce anti-tumor immunity that was being restricted by the PD-1/PD-L1 signaling axis, and that PD-1 could reverse innate immune resistance to induce durable, effective anti-tumor immune responses. Using a CD44-targeting APC, we demonstrated the ability of PD-1 immune checkpoint blockade to significantly enhance antigen-specific anti-tumor immunity induced by NIR-PIT in multiple syngeneic tumor models (MC38, LLC, and MOC1 cancer cell line). In two of three models, NIR-PIT monotherapy halted tumor growth, enhanced dendritic cell tumor infiltration, and induced de novo tumor antigen-specific T-cell responses absent at baseline. The addition of PD-1 blockade appeared to reverse adaptive immune resistance, resulting in both enhanced pre-existing tumor antigen-specific T-cell responses and enhanced de novo T-cell responses induced by NIR-PIT. Enhanced immune responses appeared to correlate with shared tumor antigen expression, suggesting that antigenicity is a major determinant of response to combination NIR-PIT and PD-1 blockade. Combination treatment induced complete rejection of MC38 tumors treated with NIR-PIT as well as untreated, distant tumors. Accordingly, tumor antigen-specific T-cell responses were measured in both treated and untreated tumors, validating the development of systemic anti-tumor immunity. Cured mice resisted tumor challenge, indicating the presence of systemic immune memory. Cumulatively these results demonstrate reversal of adaptive immune resistance following induction of innate and adaptive immunity by NIR-PIT, resulting in high rates of tumor rejection and/or significant tumor growth control in highly antigenic syngeneic models of cancer.

Citation Format: Tadanobu Nagaya, Jay Friedman, Yasuhiro Maruoka, Fusa Ogata, Shuhei Okuyama, Paul E. Clavijo, Peter L. Choyke, Clint Allen, Hisataka Kobayashi. Host immunity following near infrared photoimmunotherapy is enhanced with PD-1 checkpoint blockade to eradicate established highly antigenic tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3206.

Safety and clinical activity of PD-L1 blockade in patients with aggressive recurrent respiratory papillomatosis

Background

Recurrent respiratory papillomatosis (RRP) is a human papillomavirus (HPV)-driven disorder that causes substantial morbidity and can lead to fatal distal airway obstruction and post-obstructive pneumonias. Patients require frequent surgical debridement of disease, and no approved systemic adjuvant therapies exist.

Methods

A phase II study was conducted to investigate the clinical activity and safety of programmed death-ligand 1 (PD-L1) blockade with avelumab in patients with RRP.

Results

Twelve patients were treated. All patients with laryngeal RRP displayed improvement in disease burden, and 5 of 9 (56%) displayed partial responses. None of 4 patients with pulmonary RRP displayed a response. Using each patient’s surgical history as their own control, patients required fewer surgical interventions after avelumab treatment (p = 0.008). A subset of partial responders developed HPV-specific reactivity in papilloma-infiltrating T-cells that correlated with reduced HPV viral load and an increased Tissue Inflammation Signature.

Conclusions

Avelumab demonstrated safety and clinical activity in patients with laryngeal RRP. Further study of immune checkpoint blockade for RRP, possibly with longer treatment duration or in combination with other immunotherapies aimed at activating antiviral immunity, is warranted.

Trial registration

NCT, number NCT02859454, registered August 9, 2016.

Electronic supplementary material

The online version of this article (10.1186/s40425-019-0603-3) contains supplementary material, which is available to authorized users.

Inhibiting myeloid-derived suppressor cell trafficking enhances T cell immunotherapy

Recruitment of myeloid-derived suppressor cells (MDSCs) into tumors induces local immunosuppression in carcinomas. Here, we assessed whether SX-682, an orally bioavailable small-molecule inhibitor of CXCR1 and CXCR2, could block tumor MDSC recruitment and enhance T cell activation and antitumor immunity following multiple forms of immunotherapy. CXCR2+ neutrophilic MDSCs (PMN-MDSCs) were the most abundant myeloid cell subset within oral and lung syngeneic carcinomas. PMN-MDSCs demonstrated greater suppression of tumor-infiltrating lymphocyte killing of targets compared with macrophages. SX-682 significantly inhibited trafficking of PMN-MDSCs without altering CXCR2 ligand expression. Trafficking of CXCR1+ macrophages was unaltered, possibly due to coexpression of CSF1R. Reduced PMN-MDSC tumor infiltration correlated with enhanced accumulation of endogenous or adoptively transferred T cells. Accordingly, tumor growth inhibition or the rate of established tumor rejection following programed death-axis (PD-axis) immune checkpoint blockade or adoptive cell transfer of engineered T cells was enhanced in combination with SX-682. Despite CXCR1/2 expression on tumor cells, SX-682 appeared to have little direct antitumor effect on these carcinoma models. These data suggest that tumor-infiltrating CXCR2+ PMN-MDSCs may prevent optimal responses following both PD-axis immune checkpoint blockade and adoptive T cell transfer therapy. Abrogation of PMN-MDSC trafficking with SX-682 enhances T cell-based immunotherapeutic efficacy and may be of benefit to patients with MDSC-infiltrated cancers.

Lymphotoxin-β receptor-NIK signaling induces alternative RELB/NF-κB2 activation to promote metastatic gene expression and cell migration in head and neck cancer

Head and neck squamous cell carcinomas (HNSCC) preferentially spread to regional cervical tissues and lymph nodes. Here, we hypothesized that lymphotoxin-β (LTβ), receptor LTβR, and NF-κB-inducing kinase (NIK), promote the aberrant activation of alternative NF-κB2/RELB pathway and genes, that enhance migration and invasion of HNSCC. Genomic and expression alterations of the alternative NF-kB pathway were examined in 279 HNSCC tumors from The Cancer Genome Atlas (TCGA) and a panel of HNSCC lines. LTβR is amplified or overexpressed in HNSCC of the larynx or oral cavity, while LTβ, NIK, and RELB are overexpressed in cancers arising within lymphoid oropharyngeal and tonsillar sites. Similarly, subsets of HNSCC lines displayed overexpression of LTβR, NIK, and RELB proteins. Recombinant LTβ, and siRNA depletion of endogenous LTβR and NIK, modulated expression of LTβR, NIK, and nuclear translocation of NF-κB2(p52)/RELB as well as functional NF-κB promoter reporter activity. Treatment with a NIK inhibitor (1,3[2H,4H]-Iso-Quinoline Dione) reduced the protein expression of NIK and NF-κB2(p52)/RELB, and blocked LTβ induced nuclear translocation of RELB. NIK and RELB siRNA knockdown or NIK inhibitor slowed HNSCC migration or invation in vitro. LTβ-induces expression of migration and metastasis related genes, including hepatocyte growth/scatter factor receptor MET. Knockdown of NIK or MET similarly inhibited the migration of HNSCC cell lines. This may help explain why HNSCC preferentially migrate to local lymph nodes, where LTβ is expressed. Our findings show that LTβ/LTβR promotes activation of the alternative NIK-NF-κB2/RELB pathway to enhance MET-mediated cell migration in HNSCC, which could be potential therapeutic targets in HNSCC.

Integrated Genomic and Functional microRNA Analysis Identifies miR-30-5p as a Tumor Suppressor and Potential Therapeutic Nanomedicine in Head and Neck Cancer

PURPOSE

To identify deregulated and inhibitory miRNAs and generate novel mimics for replacement nanomedicine for head and neck squamous cell carcinomas (HNSCC).

EXPERIMENTAL DESIGN

We integrated miRNA and mRNA expression, copy number variation, and DNA methylation results from The Cancer Genome Atlas (TCGA), with a functional genome-wide screen.

RESULTS

We reveal that the miR-30 family is commonly repressed, and all 5 members sharing these seed sequence similarly inhibit HNSCC proliferation in vitro. We uncover a previously unrecognized inverse relationship with overexpression of a network of important predicted target mRNAs deregulated in HNSCC, that includes key molecules involved in proliferation (EGFR, MET, IGF1R, IRS1, E2F7), differentiation (WNT7B, FZD2), adhesion, and invasion (ITGA6, SERPINE1). Reexpression of the most differentially repressed family member, miR-30a-5p, suppressed this mRNA program, selected signaling proteins and pathways, and inhibited cell proliferation, migration, and invasion in vitro. Furthermore, a novel miR-30a-5p mimic formulated into a targeted nanomedicine significantly inhibited HNSCC xenograft tumor growth and target growth receptors EGFR and MET in vivo. Significantly decreased miR-30a/e family expression was related to DNA promoter hypermethylation and/or copy loss in TCGA data, and clinically with decreased disease-specific survival in a validation dataset. Strikingly, decreased miR-30e-5p distinguished oropharyngeal HNSCC with poor prognosis in TCGA (P = 0.002) and validation (P = 0.007) datasets, identifying a novel candidate biomarker and target for this HNSCC subset.

CONCLUSIONS

We identify the miR-30 family as an important regulator of signal networks and tumor suppressor in a subset of HNSCC patients, which may benefit from miRNA replacement nanomedicine therapy.

Host Immunity Following Near-Infrared Photoimmunotherapy Is Enhanced with PD-1 Checkpoint Blockade to Eradicate Established Antigenic Tumors

Near-infrared photoimmunotherapy (NIR-PIT) induces immunogenic cell death but has mostly failed to induce durable antitumor responses in syngenic tumor mouse models. We hypothesized that adaptive immune resistance could be limiting durable responses after treatmemt with NIR-PIT. We investigated the effects of combining NIR-PIT targeting cell-surface CD44 and PD-1 blockade in multiple syngeneic tumor models. In two of three models, NIR-PIT monotherapy halted tumor growth, enhanced dendritic cell tumor infiltration, and induced de novo tumor antigen-specific T-cell responses absent at baseline. The addition of PD-1 blockade reversed adaptive immune resistance, resulting in both enhanced preexisting tumor antigen-specific T-cell responses and enhanced de novo T-cell responses induced by NIR-PIT. Enhanced immune responses correlated with shared tumor antigen expression, suggesting that antigenicity is a major determinant of response to combination NIR-PIT and PD-1 blockade. Combination treatment induced complete rejection of MC38 tumors treated with NIR-PIT, as well as untreated, distant tumors. Accordingly, tumor antigen-specific T-cell responses were measured in both treated and untreated tumors, validating the development of systemic antitumor immunity. Mice that cleared tumors resisted subsequent tumor challenge, indicating the presence of systemic immune memory. Cumulatively, these results demonstrate reversal of adaptive immune resistance following induction of innate and adaptive immunity by NIR-PIT, resulting in high rates of tumor rejection and/or significant tumor growth control in antigenic syngeneic models of cancer.

Semaphorin4D Inhibition Improves Response to Immune-Checkpoint Blockade via Attenuation of MDSC Recruitment and Function

Tumor infiltration by immunosuppressive myeloid cells, such as myeloid-derived suppressor cells (MDSCs), causes resistance to immunotherapy. Semaphorin4D, originally characterized for its axonal guidance properties, also contributes to endothelial cell migration and survival and modulates global immune cytokine profiles and myeloid cell polarization within the tumor microenvironment. Here, we show how a therapeutic murine Sema4D mAb improves responses to immune-checkpoint blockade (ICB) in two murine carcinoma models. Treatment of tumor-bearing mice with Sema4D mAb abrogated Ly6G^hi PMN-MDSC recruitment through reducing MAPK-dependent chemokine production by tumor cells in Murine oral cancer-1 (MOC1) tumors. PMN-MDSC suppressive capacity was reduced through inhibition of Sema4D-driven arginase expression. These changes led to enhanced tumor infiltration by CD8⁺ TIL and activation of tumor-draining lymph node T lymphocytes in response to tumor antigen. Sema4D mAb in combination with either CTLA-4 or PD-1 blockade enhanced rejection of tumors or tumor growth delay, resulting in prolonged survival with either treatment. This function of Sema4D mAb provides a rationale for its evaluation in combination with ICB to treat tumors with immunosuppressive myeloid infiltration.

Attenuated TRAF3 Fosters Activation of Alternative NF-κB and Reduced Expression of Antiviral Interferon, TP53, and RB to Promote HPV-Positive Head and Neck Cancers

Human papilloma viruses (HPV) are linked to an epidemic increase in oropharyngeal head and neck squamous cell carcinomas (HNSCC), which display viral inactivation of tumor suppressors TP53 and RB1 and rapid regional spread. However, the role of genomic alterations in enabling the modulation of pathways that promote the aggressive phenotype of these cancers is unclear. Recently, a subset of HPV⁺ HNSCC has been shown to harbor novel genetic defects or decreased expression of TNF receptor-associated factor 3 (TRAF3). TRAF3 has been implicated as a negative regulator of alternative NF-κB pathway activation and activator of antiviral type I IFN response to other DNA viruses. How TRAF3 alterations affect pathogenesis of HPV⁺ HNSCC has not been extensively investigated. Here, we report that TRAF3-deficient HPV⁺ tumors and cell lines exhibit increased expression of alternative NF-κB pathway components and transcription factors NF-κB2/RELB. Overexpression of TRAF3 in HPV⁺ cell lines with decreased endogenous TRAF3 inhibited NF-κB2/RELB expression, nuclear localization, and NF-κB reporter activity, while increasing the expression of IFNA1 mRNA and protein and sensitizing cells to its growth inhibition. Overexpression of TRAF3 also enhanced TP53 and RB tumor suppressor proteins and decreased HPV E6 oncoprotein in HPV⁺ cells. Correspondingly, TRAF3 inhibited cell growth, colony formation, migration, and resistance to TNFα and cisplatin-induced cell death. Conversely, TRAF3 knockout enhanced colony formation and proliferation of an HPV⁺ HNSCC line expressing higher TRAF3 levels. Together, these findings support a functional role of TRAF3 as a tumor suppressor modulating established cancer hallmarks in HPV⁺ HNSCC.Significance: These findings report the functional role of TRAF3 as a tumor suppressor that modulates the malignant phenotype of HPV⁺ head and neck cancers. Cancer Res; 78(16); 4613-26. ©2018 AACR.

Epigenetic priming of both tumor and NK cells augments antibody-dependent cellular cytotoxicity elicited by the anti-PD-L1 antibody avelumab against multiple carcinoma cell types

Checkpoint inhibitors targeting the PD-1/PD-L1 axis are promising immunotherapies shown to elicit objective responses against multiple tumor types, yet these agents fail to benefit most patients with carcinomas. This highlights the need to develop effective therapeutic strategies to increase responses to PD-1/PD-L1 blockade. Histone deacetylase (HDAC) inhibitors in combination with immunotherapies have provided preliminary evidence of anti-tumor effects. We investigated here whether exposure of either natural killer (NK) cells and/or tumor cells to two different classes of HDAC inhibitors would augment (a) NK cell‒mediated direct tumor cell killing and/or (b) antibody-dependent cellular cytotoxicity (ADCC) using avelumab, a fully human IgG1 monoclonal antibody targeting PD-L1. Treatment of a diverse array of human carcinoma cells with a clinically relevant dose of either the pan-HDAC inhibitor vorinostat or the class I HDAC inhibitor entinostat significantly enhanced the expression of multiple NK ligands and death receptors resulting in enhanced NK cell‒mediated lysis. Moreover, HDAC inhibition enhanced tumor cell PD-L1 expression both in vitro and in carcinoma xenografts. These data demonstrate that treatment of a diverse array of carcinoma cells with two different classes of HDAC inhibitors results in enhanced NK cell tumor cell lysis and avelumab-mediated ADCC. Furthermore, entinostat treatment of NK cells from healthy donors and PBMCs from cancer patients induced an activated NK cell phenotype, and heightened direct and ADCC-mediated healthy donor NK lysis of multiple carcinoma types. This study thus extends the mechanism and provides a rationale for combining HDAC inhibitors with PD-1/PD-L1 checkpoint blockade to increase patient responses to anti-PD-1/PD-L1 therapies.

WEE1 kinase inhibition reverses G2/M cell cycle checkpoint activation to sensitize cancer cells to immunotherapy

Intrinsic resistance to cytotoxic T-lymphocyte (CTL) killing limits responses to immune activating anti-cancer therapies. Here, we established that activation of the G2/M cell cycle checkpoint results in tumor cell cycle pause and protection from granzyme B-induced cell death. This was reversed with WEE1 kinase inhibition, leading to enhanced CTL killing of antigen-positive tumor cells. Similarly, but at a later time point, cell cycle pause following TNFα exposure was reversed with WEE1 kinase inhibition, leading to CTL transmembrane TNFα-dependent induction of apoptosis and necroptosis in bystander antigen-negative tumor cells. Results were reproducible in models of oral cavity carcinoma, melanoma and colon adenocarcinoma harboring variable Tp53 genomic alterations. WEE1 kinase inhibition sensitized tumors to PD-1 mAb immune checkpoint blockade in vivo, resulting in CD8⁺-dependent rejection of established tumors harboring antigen-positive or mixed antigen-positive and negative tumor cells. Together, these data describe activation of the G2/M cell cycle checkpoint in response to early and late CTL products as a mechanism of resistance to CTL killing, and provide pre-clinical rationale for the clinical combination of agents that inhibit cell cycle checkpoints and activate anti-tumor immunity.

Abstract 3906: Inhibition ofNF-kB Inducing Kinase (NIK) to supressNF-kB alternative pathway and cell migration in HNSCC

Nuclear factor-κB (NF-κB) activation through the alternative pathway has been implicated in cancer progression and survival, however the regulatory signaling and biological significances are not well understood, especially in head and neck squamous cell carcinoma (HNSCC). NF-κB-inducing kinase (NIK) is a key molecule in the alternative NF-κB pathway, which receives signals from Lymphotoxin beta/Lymphotoxin beta receptor (LTβ/LTβR) to activate Inhibitor-κB kinase α (IKKα) and transcription factors RELB/NF-κB2. In a panel of HNSCC cell lines, we observed that dysregulation of the alternative NF-κB pathway occurred primarily through increased LTβ receptor signaling via NIK and the non-canonical NF-κB subunits. We identified a NIK inhibitor 1, 3[2H, 4H]-Iso-Quinoline Dione, which inhibited cell migration at a low dose range, but exhibited minimal anti-proliferative effect in HPV(-) HNSCC cell lines. The biological effects of the inhibitor were through suppression of the alternative NF-κB signaling. Using Western blot and immunofluorescence staining, we showed that the inhibitor reduced the protein expression and/or phosphorylation of NIK, IKKα, and RELB/NF-κB2 (p52) in the cytoplasm, and/or the protein translocation in the nucleus. The NIK inhibitor also blocked LTβ induced translocation of RELB to the nucleus. The effects of NIK inhibitor were validated by knockdown of NIK using siRNA, which inhibited cell migration and LTβ-induced expression of MET. Met is a hepatocyte growth factor receptor implicated in promoting metastasis, and knockdown of MET slowed down HNSCC cell migration. We further extended the study on a murine oral metastasis cell line MOC2, which is a syngeneic mouse model suitable for testing drug effects on tumor growth and migration in vivo. We found that the NIK inhibitor decreased cell proliferation, migration, and invasion through an extracellular matrix barrier at low concentration ranges. Currently, we have identified a potent and selective small molecule NIK inhibitor, which is orally bioavailable and active in vivo. We plan to test the effects of this NIK inhibitor on HNSCC tumor growth and metastasis in the syngeneic MOC2 model. Our study may shed light on how HNSCC tumors migrate and metastasize to local lymph nodes, where the microenvironment promotes alternative NF-κB activation by LTβ through NIK signaling. Targeting NIK mediated alternative NF-κB activation could be a potential therapeutic strategy for preventing tumor migration and metastasis of HNSCC. (Supported by NIDCD intramural projects ZIA-DC-000016, 74)

Citation Format: Rita Das, Paul E. Clavijo, Clint Allen, Anthony Saleh, Zhong Chen, Carter Van Waes. Inhibition ofNF-kB Inducing Kinase (NIK) to supressNF-kB alternative pathway and cell migration in HNSCC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3906.

Abstract 1762: Shifting the tumor microenvironment with first-in-class semaphorin 4D mab for combination immunotherapy

Purpose: In preclinical models, tumor growth inhibition by anti-semaphorin 4D (SEMA4D, CD100) blocking antibody is enhanced when combined with various immunotherapies. Immune checkpoint combinations with humanized VX15/2503 anti-SEMA4D are currently being evaluated in several clinical trials. Methods: Expanded mechanistic studies in preclinical models investigate the effect of SEMA4D signaling through its Plexin receptors (PLXN) on MDSC function and chemokine secretion in the tumor microenvironment. Humanized VX15/2503 anti-SEMA4D is now also being evaluated as single agent or in combination with other immunotherapies in four clinical trials:: (i) a Phase 1b/2a combination trial of VX15/2503 with avelumab in NSCLC (CLASSICAL-Lung); (ii) a phase 1 combination trial with nivolumab or ipilimumab in melanoma patients who have progressed on any anti-PD-1/PD-L1; (iii) a neoadjuvant integrated biomarker trial in patients with metastatic colorectal and pancreatic cancers treated with VX15/2503 in combination with nivolumab or ipilimumab; and (iv) a Phase 1/2 trial of VX15/2503 in children with solid tumors and children and young adults with osteosarcoma. Results: SEMA4D plays a multi-faceted role within the tumor microenvironment by creating a barrier at the tumor-stroma margin to restrict immune cell infiltration and promoting immunosuppressive activity of myeloid-derived cells. SEMA4D directly enhanced ability of MDSC to suppress T cell proliferation and antibody blockade reversed these effects, both in vitro and in vivo. Furthermore, SEMA4D-PLXN signaling modulates expression of chemokines that recruit MDSC. Importantly, anti-SEMA4D MAb can enhance activity of co-administered immunotherapies in murine colon, head and neck (HNSCC), and melanoma models. For example, anti-SEMA4D plus anti-CTLA-4 results in 100% survival and 90% complete tumor rejection (CR) (p<0.0001) in an HNSCC model representative of a T cell inflamed tumor with high MDSC suppression. Entinostat has broad immunomodulatory effects, including reduction of MDSC, and combination treatment of established Colon26 tumors with anti-SEMA4D and entinostat results in maximal tumor growth delay and 90% CR (p<0.0001). Conclusions: SEMA4D blockade represents a novel approach to promote functional immune infiltration into the tumor, reduce mesenchymal suppression, and enhance immunotherapy. VX15/2503 treatment was well tolerated in a Phase I trial in patients with advanced refractory solid tumors. Several clinical trials are in progress to evaluate safety, tolerability, efficacy, and biological endpoints, including immunophenotyping tumors and blood of patients treated with VX15/2503 in combination with immune checkpoint antibodies. Finally, a pediatric phase 1/2 trial based on the previously described role of SEMA4D as an oncogene in osteosarcoma and its immunomodulatory effects is being conducted.

Citation Format: Elizabeth E. Evans, Holm Bussler, Crystal Mallow, Christine Reilly, Sebold Torno, Maria Scrivens, Alan Howell, Leslie Balch, John E. Leonard, Terrence Fisher, Clint Allen, Paul E. Clavijo, Gregory Lesinski, Christina Wu, Siwen Hu-Lieskovan, Antoni Ribas, Emily G. Greengard, Ernest S. Smith, Maurice Zauderer. Shifting the tumor microenvironment with first-in-class semaphorin 4D mab for combination immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1762.

Attenuated TRAF3 Fosters Activation of Alternative NF-κB and Reduced Expression of Antiviral Interferon, TP53, and RB to Promote HPV-Positive Head and Neck Cancers

Human papilloma viruses (HPV) are linked to an epidemic increase in oropharyngeal head and neck squamous cell carcinomas (HNSCC), which display viral inactivation of tumor suppressors TP53 and RB1 and rapid regional spread. However, the role of genomic alterations in enabling the modulation of pathways that promote the aggressive phenotype of these cancers is unclear. Recently, a subset of HPV⁺ HNSCC has been shown to harbor novel genetic defects or decreased expression of TNF receptor-associated factor 3 (TRAF3). TRAF3 has been implicated as a negative regulator of alternative NF-κB pathway activation and activator of antiviral type I IFN response to other DNA viruses. How TRAF3 alterations affect pathogenesis of HPV⁺ HNSCC has not been extensively investigated. Here, we report that TRAF3-deficient HPV⁺ tumors and cell lines exhibit increased expression of alternative NF-κB pathway components and transcription factors NF-κB2/RELB. Overexpression of TRAF3 in HPV⁺ cell lines with decreased endogenous TRAF3 inhibited NF-κB2/RELB expression, nuclear localization, and NF-κB reporter activity, while increasing the expression of IFNA1 mRNA and protein and sensitizing cells to its growth inhibition. Overexpression of TRAF3 also enhanced TP53 and RB tumor suppressor proteins and decreased HPV E6 oncoprotein in HPV⁺ cells. Correspondingly, TRAF3 inhibited cell growth, colony formation, migration, and resistance to TNFα and cisplatin-induced cell death. Conversely, TRAF3 knockout enhanced colony formation and proliferation of an HPV⁺ HNSCC line expressing higher TRAF3 levels. Together, these findings support a functional role of TRAF3 as a tumor suppressor modulating established cancer hallmarks in HPV⁺ HNSCC.Significance: These findings report the functional role of TRAF3 as a tumor suppressor that modulates the malignant phenotype of HPV⁺ head and neck cancers. Cancer Res; 78(16); 4613-26. ©2018 AACR.

Nanocomplex-based TP53 gene therapy promotes anti-tumor immunity through TP53- and STING-dependent mechanisms

Loss or mutation of TP53 has been linked to alterations in anti-tumor immunity as well as dysregulation of cell cycle and apoptosis. We explored immunologic effects and mechanisms following restoration of wild-type human TP53 cDNA in murine oral cancer cells using the therapeutic nanocomplex scL-53. We demonstrated scL-53 induces dose-dependent expression of TP53 and induction of apoptosis and immunogenic cell death. We further demonstrated both TP53-dependent and independent induction of tumor cell immunogenicity through the use of blocking mAbs, nanocomplex loaded with DNA plasmid with or without TP53 cDNA, empty nanocomplex and siRNA knockdown techniques. TP53-independent immune modulation was observed following treatment with nanocomplex loaded with DNA plasmid lacking TP53 cDNA and abrogated in STING-deficient tumor cells, supporting the presence of a cytoplasmic DNA sensing, STING-dependent type-I IFN response. Cooperatively, TP53- and STING-dependent alterations sensitized tumor cells to CTL-mediated lysis, which was further enhanced following reversal of adaptive immune resistance with PD-1 mAb. In vivo, combination scL-53 and PD-1 mAb resulted in growth control or rejection of established tumors that was abrogated in mice depleted of CD8+ cells or in STING deficient mice. Cumulatively, this work demonstrates 1) a direct anti-tumor effects of functional TP53; 2) non-redundant TP53- and STING-dependent induction of tumor cell immunogenicity following scL-53 treatment; and 3) that adaptive immune resistance following scL-53 treatment can be reversed with PD-based immune checkpoint blockade, resulting in the rejection or control of syngeneic murine tumors. These data strongly support the clinical combination of scL-53 and immune checkpoint blockade.

PD-1 blockade reverses adaptive immune resistance induced by high-dose hypofractionated but not low-dose daily fractionated radiation

Preclinical evidence suggests that high-dose hypofractionated ionizing radiation (IR) can enhance anti-tumor immunity and result in significant tumor control when combined with immune checkpoint blockade (ICB). However, low-dose daily fractioned IR used for many tumor types including head and neck squamous cell carcinoma results in lymphopenia and may be immunosuppressive. We compared immune correlates, primary tumor and abscopal tumor control rates following the addition of PD-1 mAb to either high-dose hypofractioned (8Gyx2) or low-dose daily fractionated (2Gyx10) IR in syngeneic models of cancer. When compared to 2Gyx10 IR, 8Gyx2 IR preserved peripheral and tumor-infiltrating CD8⁺ T-lymphocyte accumulation and activation and reduced peripheral and tumor gMDSC accumulation. Regulatory T-lymphocytes were largely unaltered. Type I and I IFN levels and expression of IFN-responsive MHC class I and PD-L1 was enhanced in tumors treated with 8Gyx2 compared to 2Gyx10 IR. Functionally, tumor-specific CD8⁺ T-lymphocyte IFN responses within tumor draining lymph nodes were enhanced following 8Gyx2 IR but suppressed following 2Gyx10 IR. When combined with PD-1 mAb, reversal of adaptive immune resistance and subsequent enhancement of CD8+ cell dependent primary and abscopal tumor control was observed following 8Gyx2 but not 2Gyx10 IR. These data strongly support that compared to daily fractionated low-dose IR, high-dose hypofractionated IR preserves or enhances anti-tumor immunity and, when combined with PD-1 mAb to reverse adaptive immune resistance, promotes anti-tumor immunity to control primary and distant tumors. These data critically inform the rational design of trials combining IR and ICB.

Abstract 358: LTB and LTBR mediates alternative Nf-kB activation through NIk and RELB/NF-kB2 to promote cell migration of HNSCC

Nuclear factor-κB (NF-κB) includes a family of NF-κB/REL transcription factors that regulate key inflammatory and cancer genes, and which are aberrantly activated in head and neck squamous cell carcinomas (HNSCC). Lymphotoxin beta/Lymphotoxin beta receptor (LTβ/LTβR) can mediate activation of the “alternative” NF-κB pathway that includes NF-κB-inducing kinase (NIK), Inhibitor-κB kinase α (IKKα), and transcription factors RELB/NF-κB2. While LTβ is expressed in lymph nodes where HNSCC spread, the role of this pathway in pathogenesis of HNSCC is not well studied. Analysis of The Cancer Genome Atlas (TCGA) data reveals that LTβR is amplified or overexpressed in larynx or oral cavity HNSCC, while LTα/β, NIK, (MAP3K14) and RELB are overexpressed in oropharynx and tonsil cancers. Similarly, we observed overexpression of LTβR, NIK, and RELB proteins in subsets of HNSCC cell lines. In UM-SCC46, LTβ enhanced nuclear translocation of RELB/NF-κB2 (p52) subunit proteins, while LTβR siRNA knockdown decreased the expression of its target kinase NIK and RELB/NF-κB2 (p52). NIK knockdown also decreased RELB/NF-κB2 (p52) protein expression, whereas LTβ treatment stabilized NIK, and RELB/NF-κB2 (p52). Functional LTβ-mediated NF-κB activation was examined using a stably transfected NF-κB reporter cell line for β-lactamase/Fret activity. Knockdown of LTβR and NIK decreased NF-κB activity, whereas treatment with LTβ partially restored it. Treatment with a NIK inhibitor (1, 3[2H, 4H]-Iso-Quinoline Dione) reduced the protein expression of NIK, IKKα, and RELB/NF-κB2 (p52) in the cytoplasm and/or in the nucleus, and blocked LTβ induced translocation of RELB to nucleus. NIK and RELB knockdown by siRNA or using NIK inhibitor slowed HNSCC migration. Knockdown of NIK inhibited the LTβ-induced expression of MET, and SERPINE1 genes involved in migration, and knockdown of MET by siRNA inhibited the migration of HNSCC cell lines. Our findings show that LTβ/LTβ receptor promotes activation of the alternative NIK-IKKa-RELB/NF-κB2 pathway, to enhance MET-mediated cell migration in HNSCC. This may help explain why HNSCC exhibit migration and metastasis to local lymph nodes, where LTβ is expressed. The constitutive and LTβ induced activation of NIK and downstream NF-κB alternate pathway proteins, RELB and NF-κB2/p52 could be therapeutic targets in HNSCC.

(Supported by NIDCD intramural projects ZIA-DC-000016, 74)

Citation Format: Rita Das, Jamie Coupar, Anthony saleh, Paul E. Clavijo, Zhong Chen, Carter VanWaes. LTB and LTBR mediates alternative Nf-kB activation through NIk and RELB/NF-kB2 to promote cell migration of HNSCC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 358. doi:10.1158/1538-7445.AM2017-358

Resistance to CTLA-4 checkpoint inhibition reversed through selective elimination of granulocytic myeloid cells

Purpose

Local immunosuppression remains a critical problem that limits clinically meaningful response to checkpoint inhibition in patients with head and neck cancer. Here, we assessed the impact of MDSC elimination on responses to CTLA-4 checkpoint inhibition.

Experimental Design

Murine syngeneic carcinoma immune infiltrates were characterized by flow cytometry. Granulocytic MDSCs (gMDSCs) were depleted and T-lymphocyte antigen-specific responses were measured. Tumor-bearing mice were treated with MDSC depletion and CTLA-4 checkpoint blockade. Immune signatures within the human HNSCC datasets from The Cancer Genome Atlas (TCGA) were analyzed and differentially expressed genes from sorted human peripheral MDSCs were examined.

Results

gMDSCs accumulated with tumor progression and correlated with depletion of effector immune cells. Selective depletion of gMDSC restored tumor and draining lymph node antigen-specific T-lymphocyte responses lost with tumor progression. A subset of T-cell inflamed tumors responded to CTLA-4 mAb alone, but the addition of gMDSC depletion induced CD8 T-lymphocyte-dependent rejection of established tumors in all treated mice that resulted in immunologic memory. MDSCs differentially expressed chemokine receptors. Analysis of the head and neck cancer TCGA cohort revealed high CTLA-4 and MDSC-related chemokine and an MDSC-rich gene expression profile with a T-cell inflamed phenotype in > 60% of patients. CXCR2 and CSF1R expression was validated on sorted peripheral blood MDSCs from HNSCC patients.

Conclusions

MDSCs are a major contributor to local immunosuppression that limits responses to checkpoint inhibition in head and neck cancer. Limitation of MDSC recruitment or function represents a rational strategy to enhance responses to CTLA-4-based checkpoint inhibition in these patients.

Anti-PD-L1 Efficacy Can Be Enhanced by Inhibition of Myeloid-Derived Suppressor Cells with a Selective Inhibitor of PI3Kδ/γ

Checkpoint inhibitors are relatively inefficacious in head and neck cancers, despite an abundance of genetic alterations and a T-cell-inflamed phenotype. One significant barrier to efficacy may be the recruitment of myeloid-derived suppressor cells (MDSC) into the tumor microenvironment. Here we demonstrate functional inhibition of MDSC with IPI-145, an inhibitor of PI3Kδ and PI3Kγ isoforms, which enhances responses to PD-L1 blockade. Combination therapy induced CD8⁺ T lymphocyte-dependent primary tumor growth delay and prolonged survival only in T-cell-inflamed tumor models of head and neck cancers. However, higher doses of IPI-145 reversed the observed enhancement of anti-PD-L1 efficacy due to off-target suppression of the activity of tumor-infiltrating T lymphocytes. Together, our results offer a preclinical proof of concept for the low-dose use of isoform-specific PI3Kδ/γ inhibitors to suppress MDSC to enhance responses to immune checkpoint blockade. Cancer Res; 77(10); 2607-19. ©2017 AACR.

Established T Cell-Inflamed Tumors Rejected after Adaptive Resistance Was Reversed by Combination STING Activation and PD-1 Pathway Blockade

Patients with head and neck squamous cell carcinoma harbor T cell-inflamed and non-T cell-inflamed tumors. Despite this, only 20% of patients respond to checkpoint inhibitor immunotherapy. Lack of induction of innate immunity through pattern-recognition receptors, such as the stimulator of interferon (IFN) genes (STING) receptor, may represent a significant barrier to the development of effective antitumor immunity. Here, we demonstrate robust control of a T cell-inflamed (MOC1), but not non-T cell-inflamed (MOC2), model of head and neck cancer by activation of the STING pathway with the synthetic cyclic dinucleotide R_P,R_P dithio-c-di-GMP. Rejection or durable tumor control of MOC1 tumors was dependent upon a functional STING receptor and CD8 T lymphocytes. STING activation resulted in increased tumor microenvironment type 1 and type 2 IFN and greater expression of PD-1 pathway components in vivo Established MOC1 tumors were rejected and distant tumors abscopally controlled, after adaptive immune resistance had been reversed by the addition of PD-L1 mAb. These findings suggest that PD-1 pathway blockade may reverse adaptive immune resistance following cyclic dinucleotide treatment, enhancing both local and systemic antitumor immunity. Cancer Immunol Res; 4(12); 1061-71. ©2016 AACR.

Abstract 2904: The alternative NF-kB2/RELB pathway is activated by LTB/LTB receptor and NIK to promote cell migration and metastasis-related gene expression in HNSCC

Head and neck squamous cell carcinomas (HNSCC) are highly inflammatory and preferentially migrate and metastasize to lymph nodes. In this study, we find that LTβ/LTβR/NIK signaling mediates alternative RELB/NF-kB2 activation, which promotes activation of important cancer related genes and migration. We find that LTβ and LTβR are over expressed in subsets of HNSCC tissues and cell lines, and LTβ activates the alternative NF-κB pathway, enhancing nuclear translocation of RELB and NF-kB2/p52. Knockdown of LTβR decreased its target kinase NIK, and downstream NF-kB subunits RELB and NF-kB2/p52 protein expression. Knockdown of NIK protein decreased RELB and p52 protein expression, while LTβ treatment stabilized NIK, RELB and NF-kB2/p52 expression. Consistent with this, knockdown of LTBR and NIK functionally decreased NF-kB reporter gene activity, while treatment of LTB partially restored the NF-kB reporter activity. Notably, knockdown of NIK and RELB by siRNA inhibited cell migration in HNSCC. Since NIK is known as central regulator of the activation of the non-canonical pathway, we tested the effects of a NIK inhibitor 1,3[2H,4H]-Isoquinolinedione on NF-kB function and cell migration. NIK inhibitor decreased NIK protein in the cytoplasm, downstream nuclear expression of RELB and NF-kB2/p52 proteins by Western blot and RELB localization by immunofluorescence staining. We have found evidence for LTβ induction of migration/metastasis and cell death genes MET, BIRC3,and SERPINE1, and NIK knockdown inhibited cell migration and the inducible expression of MET, BIRC3, SERPINE 1 by LTB. Our data reveal the mechanisms how LTβ and NIK activation mediated alternative NF-kB pathway and contribute to migration and metastasis of HNSCC.

Supported by NIDCD intramural Project ZIA-DC-000016, 73 and 74.

Citation Format: Rita Das, Tsu-Fan Cheng, Jamie Coupar, Anthony Saleh, Paul E. Clavijo, Xinping Yang, Zhong Chen, Carter VanWaes. The alternative NF-kB2/RELB pathway is activated by LTB/LTB receptor and NIK to promote cell migration and metastasis-related gene expression in HNSCC. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2904.

Abstract 1448: MDSC depletion delays primary tumor growth in syngeneic models of oral cavity cancer

Carcinogen-associated oral cavity cancers are a heterogeneous group of aggressive cancers with a high recurrence rate after definitive treatment and a poor 5-year survival. The genetic alteration rate of these cancers tends to be high, and many oral cancers express immune checkpoint molecules in the tumor microenvironment with potential to respond to checkpoint blocking immunotherapy. Local immunosuppression mediated by both the tumor cells and other infiltrating immune cells are likely a major mechanism of resistance to immunotherapy. Here, we investigated the role of myeloid derived suppressor cells (MDSCs) in a highly aggressive but poorly immunogenic syngeneic model of carcinogen-induced oral cavity cancer (MOC2). Performing a time course analysis of immune infiltrates, MOC2 tumors demonstrated robust recruitment of CXCR2+CSFR1+CCR2− MDSCs that peaked at 15 days following tumor transplantation. This intratumoral accumulation of MDSCs preceded draining lymph node and splenic MDSC accumulation by 6 and 9 days respectively. The accumulation of MDSCs corresponded to a sharp decrease in the presence of tumor infiltrating CD8+ T-lymphocytes (TIL), CD4+ TIL, FoxP3+CD4+ Tregs and CD3−NK1.1+ NK cells. As CD8+ TIL numbers decreased, cell surface expression of the lymphocyte activation markers CD69, CD44 and ICOS decreased with the checkpoint molecule CTLA-4 increased. Phenotypically, the great majority of tumor-infiltrating MDSCs were granulocytic MDSCs (Ly6GhiLy6Cint), while few were monocytic MDSCs (Ly6GloLy6Chi). In a CFSE-based functional T-lymphocyte suppression assay, sorted peripheral and tumor-infiltrating MDSCs strongly suppressed T-lymphocyte proliferation at MDSC:T-lymphocyte ratios as low as 1:32. Hypothesizing that decreased tumor MDSCs would impact primary tumor growth, MOC2 tumors were allowed to engraft to 100mm3 and depletion of granulocytic MDSCs was performed with a rat anti-mouse Ly6G depleting antibody (clone RB6-8C5). This depletion resulted in a statistically significant delay in MOC2 primary tumor growth. Flow cytometric analysis of tumor tissues revealed that MDSC depletion was transient with rapid rebound of MDSC tumor infiltration within days of depleting antibody administration. This data highlights the critical role that MDSCs play in local immunosuppression and suggest that the syngeneic MOC model represents a powerful tool to study MDSC pathobiology. Functional inhibition or elimination of MDSCs from the tumor microenvironment represents an exciting adjuvant therapy that may enhance the response to checkpoint inhibition in patients with oral cavity cancer.

Citation Format: Paul E. Clavijo, Ruth Davis, Zhong Chen, Carter Van Waes, Clint T. Allen. MDSC depletion delays primary tumor growth in syngeneic models of oral cavity cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1448.

Anti-Tumor Immunity in Head and Neck Cancer: Understanding the Evidence, How Tumors Escape and Immunotherapeutic Approaches

Many carcinogen- and human papilloma virus (HPV)-associated head and neck cancers (HNSCC) display a hematopoietic cell infiltrate indicative of a T-cell inflamed phenotype and an underlying anti-tumor immune response. However, by definition, these tumors have escaped immune elimination and formed a clinically significant malignancy. A number of both genetic and environmental mechanisms may allow such immune escape, including selection of poorly antigenic cancer cell subsets, tumor produced proinflammatory and immunosuppressive cytokines, recruitment of immunosuppressive immune cell subsets into the tumor and expression of checkpoint pathway components that limit T-cell responses. Here, we explore concepts of antigenicity and immunogenicity in solid tumors, summarize the scientific and clinical data that supports the use of immunotherapeutic approaches in patients with head and neck cancer, and discuss immune-based treatment approaches currently in clinical trials.