Addition of interleukin-21 for expansion of T-cells for adoptive immunotherapy of murine melanoma

A subset of cytotoxic effector memory T cells enhances CAR T cell efficacy in a model of pancreatic ductal adenocarcinoma

In humans, the natural killer (NK) cell marker CD161 identifies several subsets of T cells, including a polyclonal CD8 αβ T cell receptor-expressing subset with characteristic specificity for tissue-localized viruses. This subset also displays enhanced cytotoxic and memory phenotypes. Here, we characterized this unique T cell subset and determined its potential suitability for use in chimeric antigen receptor (CAR) T cell therapy. In mice, gene expression profiling among the CD161-equivalent CD8⁺ T cell populations (CD8⁺NK1.1⁺) revealed substantial up-regulation of granzymes, perforin, killer lectin-like receptors, and innate signaling molecules in comparison to CD8⁺NK1.1^- T cells. Adoptive transfer of CD8⁺NK1.1⁺ cells from previously exposed animals offered substantially enhanced protection and improved survival against melanoma tumors and influenza infection compared to CD8⁺NK1.1^- cells. Freshly isolated human CD8⁺CD61⁺ T cells exhibited heightened allogeneic killing activity in comparison to CD8⁺CD61^- T cells or total peripheral blood mononuclear cells (PBMCs). To determine whether this subset might improve the antitumor efficacy of CAR T cell therapy against solid tumors, we compared bulk PBMCs, CD8⁺CD161^-, and CD8⁺CD161⁺ T cells transduced with a human epidermal growth factor receptor-2 (HER2)-specific CAR construct. In vitro, CD8⁺CD161⁺ CAR-transduced T cells killed HER2⁺ targets faster and with greater efficiency. Similarly, these cells mediated enhanced in vivo antitumor efficacy in xenograft models of HER2⁺ pancreatic ductal adenocarcinoma, exhibiting elevated expression of granzymes and reduced expression of exhaustion markers. These data suggest that this T cell subset presents an opportunity to improve CAR T cell therapy for the treatment of solid tumors.

Near-infrared photoimmunotherapy targeting human-EGFR in a mouse tumor model simulating current and future clinical trials

Background

near-infrared photoimmunotherapy (NIR-PIT) is a cancer treatment that uses antibody-photoabsorber (IRDye700DX, IR700) conjugates (APCs) which bind to target cells and are photoactivated by NIR light inducing rapid necrotic cell death. NIR-PIT targeting human epidermal growth factor receptor (hEGFR) has been shown to destroy hEGFR expressing human tumor cells and to be effective in immunodeficient mouse models. NIR-PIT can also be targeted to cells in the tumor microenvironment, for instance, CD25-targeted NIR-PIT can be used to selectively deplete regulatory T cells (Tregs) within a tumor. The aim of this study was to evaluate the combined therapeutic efficacy of hEGFR and CD25-targeted NIR-PIT in a newly established hEGFR expressing murine oropharyngeal cell line (mEERL-hEGFR).

Methods

panitumumab conjugated with IR700 (pan-IR700) was used as the cancer cell-directed component of NIR-PIT and anti-CD25-F(ab′)₂-IR700 was used as the tumor microenvironment-directed component of NIR-PIT. Efficacy was evaluated using tumor-bearing mice in four groups: (1) non-treatment group (control), (2) pan-IR700 based NIR-PIT (pan-PIT), (3) anti-CD25-F(ab′)₂-IR700 based NIR-PIT (CD25-PIT), (4) combined NIR-PIT with pan-IR700 and anti-CD25- F(ab′)₂-IR700 (combined PIT).

Findings

the combined PIT group showed the greatest inhibition of tumor growth. Destruction of cancer cells likely leads to an immune response which is amplified by the loss of Tregs in the tumor microenvironment.

Interpretation

combined hEGFR and CD25-targeted NIR-PIT is a promising treatment for hEGFR expressing cancers in which Treg cells play an immunosuppressive role.

Transcriptional Profiling of CD8+ CMV-Specific T Cell Functional Subsets Obtained Using a Modified Method for Isolating High-Quality RNA From Fixed and Permeabilized Cells

Previous studies suggest that the presence of antigen-specific polyfunctional T cells is correlated with improved pathogen clearance, disease control, and clinical outcomes; however, the molecular mechanisms responsible for the generation, function, and survival of polyfunctional T cells remain unknown. The study of polyfunctional T cells has been, in part, limited by the need for intracellular cytokine staining (ICS), necessitating fixation and cell membrane permeabilization that leads to unacceptable degradation of RNA. Adopting elements from prior research efforts, we developed and optimized a modified protocol for the isolation of high-quality RNA (i.e., RIN > 7) from primary human T cells following aldehyde-fixation, detergent-based permeabilization, intracellular cytokines staining, and sorting. Additionally, this method also demonstrated utility preserving RNA when staining for transcription factors. This modified protocol utilizes an optimized combination of an RNase inhibitor and high-salt buffer that is cost-effective while maintaining the ability to identify and resolve cell populations for sorting. Overall, this protocol resulted in minimal loss of RNA integrity, quality, and quantity during cytoplasmic staining of cytokines and subsequent flourescence-activated cell sorting. Using this technique, we obtained the transcriptional profiles of functional subsets (i.e., non-functional, monofunctional, bifunctional, polyfunctional) of CMV-specific CD8+T cells. Our analyses demonstrated that these functional subsets are molecularly distinct, and that polyfunctional T cells are uniquely enriched for transcripts involved in viral response, inflammation, cell survival, proliferation, and metabolism when compared to monofunctional cells. Polyfunctional T cells demonstrate reduced activation-induced cell death and increased proliferation after antigen re-challenge. Further in silico analysis of transcriptional data suggested a critical role for STAT5 transcriptional activity in polyfunctional cell activation. Pharmacologic inhibition of STAT5 was associated with a significant reduction in polyfunctional cell cytokine expression and proliferation, demonstrating the requirement of STAT5 activity not only for proliferation and cell survival, but also cytokine expression. Finally, we confirmed this association between CMV-specific CD8+ polyfunctionality with STAT5 signaling also exists in immunosuppressed transplant recipients using single cell transcriptomics, indicating that results from this study may translate to this vulnerable patient population. Collectively, these results shed light on the mechanisms governing polyfunctional T cell function and survival and may ultimately inform multiple areas of immunology, including but not limited to the development of new vaccines, CAR-T cell therapies, and adoptive T cell transfer.

Human papilloma virus-specific T cells can be generated from naïve T cells for use as an immunotherapeutic strategy for immunocompromised patients

Human papilloma virus (HPV) is a known cause of cervical cancer, squamous cell carcinoma and laryngeal cancer. Although treatments exist for HPV-associated malignancies, patients unresponsive to these therapies have a poor prognosis. Recent findings from vaccine studies suggest that T-cell immunity is essential for disease control. Because Epstein-Barr Virus (EBV)-specific T cells have been highly successful in treating or preventing EBV-associated tumors, we hypothesized that the development of a manufacturing platform for HPV-specific T cells from healthy donors could be used in a third-party setting to treat patients with high-risk/relapsed HPV-associated cancers. Most protocols for generating virus-specific T cells require prior exposure of the donor to the targeted virus and, because the seroprevalence of high-risk HPV types varies greatly by age and ethnicity, manufacturing of donor-derived HPV-specific T cells has proven challenging. We, therefore, made systematic changes to our current Good Manufacturing Practice (GMP)-compliant protocols to improve antigen presentation, priming and expansion for the manufacture of high-efficacy HPV-specific T cells. Like others, we found that current methodologies fail to expand HPV-specific T cells from most healthy donors. By optimizing dendritic cell maturation and function with lipopolysaccharide (LPS) and interferon (IFN)γ, adding interleukin (IL)-21 during priming and depleting memory T cells, we achieved reliable expansion of T cells specific for oncoproteins E6 and E7 to clinically relevant amounts (mean, 578-fold expansion; n = 10), which were polyfunctional based on cytokine multiplex analysis. In the third-party setting, such HPV-specific T-cell products might serve as a potent salvage therapy for patients with HPV-associated diseases.

SIRPA-Inhibited, Marrow-Derived Macrophages Engorge, Accumulate, and Differentiate in Antibody-Targeted Regression of Solid Tumors

Marrow-derived macrophages are highly phagocytic, but whether they can also traffic into solid tumors and engulf cancer cells is questionable, given the well-known limitations of tumor-associated macrophages (TAMs). Here, SIRPα on macrophages from mouse and human marrow was inhibited to block recognition of its ligand, the "marker of self" CD47 on all other cells. These macrophages were then systemically injected into mice with fluorescent human tumors that had been antibody targeted. Within days, the tumors regressed, and single-cell fluorescence analyses showed that the more the macrophages engulfed, the more they accumulated within regressing tumors. Human-marrow-derived macrophages engorged on the human tumors, while TAMs were minimally phagocytic, even toward CD47-knockdown tumors. Past studies had opsonized tumors in situ with antibody and/or relied on mouse TAMs but had not injected SIRPα-inhibited cells; also, unlike past injections of anti-CD47, blood parameters remained normal and safe. Consistent with tumor-selective engorge-and-accumulate processes in vivo, phagocytosis in vitro inhibited macrophage migration through micropores that mimic features of dense 3D tissue. Accumulation of SIRPα-inhibited macrophages in tumors favored tumor regression for 1-2 weeks, but donor macrophages quickly differentiated toward non-phagocytic, high-SIRPα TAMs. Analyses of macrophages on soft (like marrow) or stiff (like solid tumors) collagenous gels demonstrated a stiffness-driven, retinoic-acid-modulated upregulation of SIRPα and the mechanosensitive nuclear marker lamin-A. Mechanosensitive differentiation was similarly evident in vivo and likely limited the anti-tumor effects, as confirmed by re-initiation of tumor regression by fresh injections of SIRPα-inhibited macrophages. Macrophage motility, phagocytosis, and differentiation in vivo are thus coupled.

Elevation and persistence of CD8 T-cells in HIV infection: the Achilles heel in the ART era

Introduction

HIV infection leads to a disturbed T-cell homeostasis, featured by a depletion of CD4 T-cells and a persistent elevation of CD8 T-cells over disease progression. Most effort of managing HIV infection has been focused on CD4 T-cell recovery, while changes in the CD8 compartment were relatively underappreciated in the past.

Methods

A comprehensive literature review of publications in English language was conducted using major electronic databases. Our search was focused on factors contributing to CD8 T-cell dynamics in HIV infection and following antiretroviral therapy (ART).

Discussion

Normalization of CD8 counts is seldom observed even with optimal CD4 recovery following long-term treatment. Initiation of ART in primary HIV infection leads to enhanced normalization of CD8 count compared with long-term ART initiated in chronic infection. Importantly, such CD8 elevation in treated HIV infection is associated with an increased risk of inflammatory non-AIDS-related clinical events independent of CD4 T-cell recovery. The mechanisms underlying CD8 persistence remain largely unknown, which may include bystander activation, exhaustion and immunosenescence of CD8 T-cells. The information provided herein will lead to a better understanding of factors associated with CD8 persistence and contribute to the development of strategies aiming at CD8 normalization.

Conclusions

Persistence of CD8 T-cell elevation in treated HIV-infected patients is associated with an increased risk of non-AIDS-related events. Now that advances in ART have led to decreased AIDS-related opportunistic diseases, more attention has been focused on reducing non-AIDS events and normalizing persistent CD8 T-cell elevation.

Common gamma chain cytokines in combinatorial immune strategies against cancer

Common γ chain (γC) cytokines, namely IL-2, IL-4, IL-7, IL-9, IL-15, and IL-21 are important for the proliferation, differentiation, and survival of lymphocytes that display antitumor activity, thus stimulating considerable interest for the use of cytokines in cancer immunotherapy. In this review, we will focus on the γC cytokines that demonstrate the greatest potential for immunotherapy, IL-2, IL-7, IL-15, and IL-21. We will briefly cover their biological function, potential applications in cancer therapy, and update on their use in combinatorial immune strategies for eradicating tumors and hematopoietic malignancies.