NF-κB p50-deficient immature myeloid cell (p50-IMC) adoptive transfer slows the growth of murine prostate and pancreatic ductal carcinoma

Targeting PD-L1 in solid cancer with myeloid cells expressing a CAR-like immune receptor

Introduction

Solid cancers Myeloid cells are prevalent in solid cancers, but they frequently exhibit an anti-inflammatory pro-tumor phenotype that contribute to the immunosuppressive tumor microenvironment (TME), which hinders the effectiveness of cancer immunotherapies. Myeloid cells' natural ability of tumor trafficking makes engineered myeloid cell therapy an intriguing approach to tackle the challenges posed by solid cancers, including tumor infiltration, tumor cell heterogenicity and the immunosuppressive TME. One such engineering approach is to target the checkpoint molecule PD-L1, which is often upregulated by solid cancers to evade immune responses.

Method

Here we devised an adoptive cell therapy strategy based on myeloid cells expressing a Chimeric Antigen Receptor (CAR)-like immune receptor (CARIR). The extracellular domain of CARIR is derived from the natural inhibitory receptor PD-1, while the intracellular domain(s) are derived from CD40 and/or CD3ζ. To assess the efficacy of CARIR-engineered myeloid cells, we conducted proof-of-principle experiments using co-culture and flow cytometry-based phagocytosis assays in vitro. Additionally, we employed a fully immune-competent syngeneic tumor mouse model to evaluate the strategy's effectiveness in vivo.

Result

Co-culturing CARIR-expressing human monocytic THP-1 cells with PD-L1 expressing target cells lead to upregulation of the costimulatory molecule CD86 along with expression of proinflammatory cytokines TNF-1α and IL-1β. Moreover, CARIR expression significantly enhanced phagocytosis of multiple PD-L1 expressing cancer cell lines in vitro. Similar outcomes were observed with CARIR-expressing human primary macrophages. In experiments conducted in syngeneic BALB/c mice bearing 4T1 mammary tumors, infusing murine myeloid cells that express a murine version of CARIR significantly slowed tumor growth and prolonged survival.

Conclusion

Taken together, these results demonstrate that adoptive transfer of PD-1 CARIR-engineered myeloid cells represents a promising strategy for treating PD-L1 positive solid cancers.

Preclinical In Vitro and In Vivo Models for Adoptive Cell Therapy of Cancer

ABSTRACT

Adoptive cellular therapies are making major strides in the treatment of cancer, both for hematologic and solid tumors. These cellular products include chimeric antigen receptor T cells and T-cell receptor-modified T cells, tumor-infiltrating lymphocytes, marrow-infiltrating T cells, natural killer cells as well as macrophage-based therapeutics. Advancement in genomics, computational biology, immunology, and cell therapy manufacturing has facilitated advancement of adoptive T cell therapies into the clinic, whereas clinical efficacy has driven Food and Drug Administration approvals. The growth of adoptive cellular therapy has, in turn, led to innovation in the preclinical models available, from ex vivo cell-based models to in vivo xenograft models of treatment. This review focuses on the development and application of in vitro models and in vivo models (cell line xenograft, humanized mice, and patient-derived xenograft models) that directly evaluate these human cellular products.

Role of immune escape in different digestive tumours

A counterbalance between immune cells and tumour cells is key to fighting tumours, and immune escape is an important mechanism for the survival of tumour cells in the body. Tumor cells and their cytokines impair the activity of T cells, NK cells, macrophages and other immune cells through various ways, and change the expression of their own surface antigens so as to avoid the clearance of the immune system. Changes in major histocompatibility complex molecules, high expression of programmed death-ligand 1, and the presence of immunosuppressive cells in the tumor microenvironment (TME) are main means by which tumors impair the function of immune cells. During the development of tumours of the digestive system, different mechanisms acting on tumour cells, the TME, and immune cells lead to immune escape and promote tumour progression. In this paper, the mechanisms of immune escape in tumour cells of the digestive system are reviewed to provide a theoretical basis for the immunotherapy of gastrointestinal tumours.

p50 suppresses cytotoxic T lymphocyte effector function to regulate tumor immune escape and response to immunotherapy

Background

NF-κB is a key link between inflammation and cancer. Previous studies of NF-κB have largely focused on tumor cells, and the intrinsic function of NF-κB in T cells in tumor development and response to immunotherapy is largely unknown. We aimed at testing the hypothesis that NF-κB1 (p50) activation in T cells underlies human colon cancer immune escape and human cancer non-response to anti-PD-1 immunotherapy.

Methods

We screened NF-κB activation in human colon carcinoma and used mouse models to determine p50 function in tumor cells and immune cells. RNA-Seq was used to identify p50 target genes. p50 binding to target gene promoters were determined by electrophoresis mobility shift assay and chromatin immunoprecipitation. A p50 activation score was generated from gene expression profiling and used to link p50 activation to T-cell activation and function pre-nivolumab and post-nivolumab immunotherapy in human patients with cancer.

Results

p50 is the dominant form of NF-κB that is highly activated in immune cells in the human colorectal carcinoma microenvironment and neighboring non-neoplastic colon epithelial cells. Tumor cell intrinsic p50 signaling and T-cell intrinsic p50 signaling exert opposing functions in tumor growth control in vivo. Deleting Nfkb1 in tumor cells increased whereas in T cells decreased tumor growth in preclinical mouse models. Gene expression profiling identified Gzmb as a p50 target in T cells. p50 binds directly to a previously uncharacterized κB sequence at the Gzmb promoter in T cells, resulting in repression of Gzmb expression in tumor-infiltrating cytotoxic T lymphocytes (CTLs) to induce a dysfunctional CTL phenotype to promote tumor immune escape. p50 activation is inversely correlated with both GZMB expression and T-cell tumor infiltration in human colorectal carcinoma. Furthermore, nivolumab immunotherapy decreased p50 activation and increased GZMB expression in human patients with melanoma.

Conclusions

Inflammation activates p50 that binds to the Gzmb promoter to repress granzyme B expression in T cells, resulting in CTL dysfunction to confer tumor immune escape and decreased response to anti-PD-1 immunotherapy.

NF-κB and Pancreatic Cancer; Chapter and Verse

Pancreatic Ductal Adenocarcinoma (PDAC) is one of the world's most lethal cancers. An increase in occurrence, coupled with, presently limited treatment options, necessitates the pursuit of new therapeutic approaches. Many human cancers, including PDAC are initiated by unresolved inflammation. The transcription factor NF-κB coordinates many signals that drive cellular activation and proliferation during immunity but also those involved in inflammation and autophagy which may instigate tumorigenesis. It is not surprising therefore, that activation of canonical and non-canonical NF-κB pathways is increasingly recognized as an important driver of pancreatic injury, progression to tumorigenesis and drug resistance. Paradoxically, NF-κB dysregulation has also been shown to inhibit pancreatic inflammation and pancreatic cancer, depending on the context. A pro-oncogenic or pro-suppressive role for individual components of the NF-κB pathway appears to be cell type, microenvironment and even stage dependent. This review provides an outline of NF-κB signaling, focusing on the role of the various NF-κB family members in the evolving inflammatory PDAC microenvironment. Finally, we discuss pharmacological control of NF-κB to curb inflammation, focussing on novel anti-cancer agents which reinstate the process of cancer cell death, the Smac mimetics and their pre-clinical and early clinical trials.

Tumor-Associated Microglia and Macrophages in the Glioblastoma Microenvironment and Their Implications for Therapy

Glioblastoma is the most frequent and malignant primary brain tumor. Standard of care includes surgery followed by radiation and temozolomide chemotherapy. Despite treatment, patients have a poor prognosis with a median survival of less than 15 months. The poor prognosis is associated with an increased abundance of tumor-associated microglia and macrophages (TAMs), which are known to play a role in creating a pro-tumorigenic environment and aiding tumor progression. Most treatment strategies are directed against glioblastoma cells; however, accumulating evidence suggests targeting of TAMs as a promising therapeutic strategy. While TAMs are typically dichotomously classified as M1 and M2 phenotypes, recent studies utilizing single cell technologies have identified expression pattern differences, which is beginning to give a deeper understanding of the heterogeneous subpopulations of TAMs in glioblastomas. In this review, we evaluate the role of TAMs in the glioblastoma microenvironment and discuss how their interactions with cancer cells have an extensive impact on glioblastoma progression and treatment resistance. Finally, we summarize the effects and challenges of therapeutic strategies, which specifically aim to target TAMs.

Adoptive transfer of immature myeloid cells lacking NF-κB p50 (p50-IMC) impedes the growth of MHC-matched high-risk neuroblastoma

High‐risk neuroblastomas harbor abundant myeloid cells that suppress antitumor immunity and support tumor growth. Macrophages lacking the inhibitory NF‐κB p50 subunit adopt a pro‐inflammatory phenotype. We now report that murine 9464D neuroblastoma cells, which express high levels of exogenous MYCN, grow slower in syngeneic p50(f/f);Lys‐Cre mice that lack p50 in macrophages and neutrophils, compared with p50(f/f) littermates. Tumors in p50(f/f);Lys‐Cre mice possess increased numbers of total and activated CD4⁺ and CD8⁺ T cells, and depletion of both of these T‐cell populations accelerates tumor growth. Anti‐PD‐1 T‐cell checkpoint blockade, or DNA methyltransferase and histone deacetylase inhibition, further slows tumor growth. In addition, adoptive transfer of immature myeloid cells lacking NF‐κB p50 (p50‐IMC), generated either from the bone marrow of p50^−/− mice or via nucleofection of a p50 sgRNA:Cas9 complex into wild‐type hematopoietic progenitors, also slowed growth of MHC‐matched 9464D tumors but not of MHC‐mismatched Neuro2A tumors. These findings further validate the utility of targeting myeloid NF‐κB p50 as a strategy for cancer therapy and demonstrate activity of p50‐IMC generated by gene editing of syngeneic marrow cells, a cell product relevant to clinical translation.

NF-κB in Cancer Immunity: Friend or Foe?

The emergence of immunotherapies has definitely proven the tight relationship between malignant and immune cells, its impact on cancer outcome and its therapeutic potential. In this context, it is undoubtedly critical to decipher the transcriptional regulation of these complex interactions. Following early observations demonstrating the roles of NF-κB in cancer initiation and progression, a series of studies converge to establish NF-κB as a master regulator of immune responses to cancer. Importantly, NF-κB is a family of transcriptional activators and repressors that can act at different stages of cancer immunity. In this review, we provide an overview of the selective cell-intrinsic contributions of NF-κB to the distinct cell types that compose the tumor immune environment. We also propose a new view of NF-κB targeting drugs as a new class of immunotherapies for cancer.