Redistribution, hyperproliferation, activation of natural killer cells and CD8 T cells, and cytokine production during first-in-human clinical trial of recombinant human interleukin-15 in patients with cancer

Sarcopenia Was a Poor Prognostic Predictor for Patients With Advanced Lung Cancer Treated With Immune Checkpoint Inhibitors

Background

It remains not well known whether skeletal muscle mass (SMM) loss has any impact on the effectiveness of immune checkpoint inhibitors (ICIs) in patients with advanced lung cancer. We aimed to evaluate the association between SMM and clinical outcome of patients with advanced lung cancer receiving ICIs as first line or second line.

Materials and Methods

From March 1st, 2019 to March 31st, 2021 at our hospital, 34 patients with advanced lung cancer treated with first-line or second-line ICIs were enrolled retrospectively. The estimation of skeletal muscle index (SMI) for sarcopenia was assessed at the level of the third lumbar vertebra (L3) on computed tomography (CT) images obtained within 4 weeks before initiation of ICIs treatment. The impact of sarcopenia (low SMI) on progression free survival (PFS) was analyzed using Kaplan-Meier method and log-rank tests. The effect of various variables on PFS was evaluated using Cox proportional hazards regression model with univariate and multivariate analysis. The impact on treatment response including objective response rate (ORR) and disease control rate (DCR) and immunotherapy related adverse events (irAEs) between patients with and without sarcopenia was compared by the chi-squared test. The comparison of SMI value between patients with objective response (OR), disease control (DC) and those without OR and DC was used student t-test or Mann-Whitney U test.

Results

Both in univariate and multivariate analysis, sarcopenia and treatment lines were the predictive factors for PFS (p < 0.05). Patients with sarcopenia had significantly shorter PFS than that of non-sarcopenic ones [6.57 vs. 16.2 months, hazard ratios (HR) = 2.947 and 3.542, and 95% confidence interval (CI): 1.123–13.183 and 1.11–11.308, p = 0.022 and 0.033]. No significant difference in ORR and irAEs was found. Patients with sarcopenia had lower DCR than those without sarcopenia. The mean SMI value of DCR group and non-DCR group was 32.94 ± 5.49 and 44.77 ± 9.06 cm²/m², respectively (p = 0.008).

Conclusion

Sarcopenia before immunotherapy might be a significant predictor for poor prognosis including shorter PFS and lower DCR in patients with advanced lung cancer treated with ICIs as first line or second line.

Reshaping the systemic tumor immune environment (STIE) and tumor immune microenvironment (TIME) to enhance immunotherapy efficacy in solid tumors

The development of combination immunotherapy based on the mediation of regulatory mechanisms of the tumor immune microenvironment (TIME) is promising. However, a deep understanding of tumor immunology must involve the systemic tumor immune environment (STIE) which was merely illustrated previously. Here, we aim to review recent advances in single-cell transcriptomics and spatial transcriptomics for the studies of STIE, TIME, and their interactions, which may reveal heterogeneity in immunotherapy responses as well as the dynamic changes essential for the treatment effect. We review the evidence from preclinical and clinical studies related to TIME, STIE, and their significance on overall survival, through different immunomodulatory pathways, such as metabolic and neuro-immunological pathways. We also evaluate the significance of the STIE, TIME, and their interactions as well as changes after local radiotherapy and systemic immunotherapy or combined immunotherapy. We focus our review on the evidence of lung cancer, hepatocellular carcinoma, and nasopharyngeal carcinoma, aiming to reshape STIE and TIME to enhance immunotherapy efficacy.

Interleukin 15 in Cell-Based Cancer Immunotherapy

Cell-based cancer immunotherapy, such as chimeric antigen receptor (CAR) engineered T and natural killer (NK) cell therapies, has become a revolutionary new pillar in cancer treatment. Interleukin 15 (IL-15), a potent immunostimulatory cytokine that potentiates T and NK cell immune responses, has demonstrated the reliability and potency to potentially improve the therapeutic efficacy of current cell therapy. Structurally similar to interleukin 2 (IL-2), IL-15 supports the persistence of CD8⁺ memory T cells while inhibiting IL-2-induced T cell death that better maintains long-term anti-tumor immunity. In this review, we describe the biology of IL-15, studies on administrating IL-15 and/or its derivatives as immunotherapeutic agents, and IL-15-armored immune cells in adoptive cell therapy. We also discuss the advantages and challenges of incorporating IL-15 in cell-based immunotherapy and provide directions for future investigation.

NK Cell-Based Immunotherapy in Colorectal Cancer

Human Natural Killer (NK) cells are all round players in immunity thanks to their powerful and immediate response against transformed cells and the ability to modulate the subsequent adaptive immune response. The potential of immunotherapies based on NK cell involvement has been initially revealed in the hematological setting but has inspired the design of different immune tools to also be applied against solid tumors, including colorectal cancer (CRC). Indeed, despite cancer prevention screening plans, surgery, and chemotherapy strategies, CRC is one of the most widespread cancers and with the highest mortality rate. Therefore, further efficient and complementary immune-based therapies are in urgent need. In this review, we gathered the most recent advances in NK cell-based immunotherapies aimed at fighting CRC, in particular, the use of monoclonal antibodies targeting tumor-associated antigens (TAAs), immune checkpoint blockade, and adoptive NK cell therapy, including NK cells modified with chimeric antigen receptor (CAR-NK).

Next Generation Natural Killer Cells for Cancer Immunotherapy

In recent years, immunotherapy for cancer has become mainstream with several products now authorized for therapeutic use in the clinic and are becoming the standard of care for some malignancies. Chimeric antigen receptor (CAR)-T cell therapies have demonstrated substantial efficacy for the treatment of hematological malignancies; however, they are complex and currently expensive to manufacture, and they can generate life-threatening adverse events such as cytokine release syndrome (CRS). The limitations of current CAR-T cells therapies have spurred an interest in alternative immunotherapy approaches with safer risk profiles and with less restrictive manufacturing constraints. Natural killer (NK) cells are a population of immune effector cells with potent anti-viral and anti-tumor activity; they have the capacity to swiftly recognize and kill cancer cells without the need of prior stimulation. Although NK cells are naturally equipped with cytotoxic potential, a growing body of evidence shows the added benefit of engineering them to better target tumor cells, persist longer in the host, and be fitter to resist the hostile tumor microenvironment (TME). NK-cell-based immunotherapies allow for the development of allogeneic off-the-shelf products, which have the potential to be less expensive and readily available for patients in need. In this review, we will focus on the advances in the development of engineering of NK cells for cancer immunotherapy. We will discuss the sourcing of NK cells, the technologies available to engineer NK cells, current clinical trials utilizing engineered NK cells, advances on the engineering of receptors adapted for NK cells, and stealth approaches to avoid recipient immune responses. We will conclude with comments regarding the next generation of NK cell products, i.e., armored NK cells with enhanced functionality, fitness, tumor-infiltration potential, and with the ability to overcome tumor heterogeneity and immune evasion.

Development and Characterization of an Anti-Cancer Monoclonal Antibody for Treatment of Human Carcinomas

NEO-201 is an IgG1 humanized monoclonal antibody (mAb) that binds to tumor-associated variants of carcinoembryonic antigen-related cell adhesion molecule (CEACAM)-5 and CEACAM-6. NEO-201 reacts to colon, ovarian, pancreatic, non-small cell lung, head and neck, cervical, uterine and breast cancers, but is not reactive against most normal tissues. NEO-201 can kill tumor cells via antibody-dependent cell-mediated cytotoxicity (ADCC) and complement dependent cytotoxicity (CDC) to directly kill tumor cells expressing its target. We explored indirect mechanisms of its action that may enhance immune tumor killing. NEO-201 can block the interaction between CEACAM-5 expressed on tumor cells and CEACAM-1 expressed on natural killer (NK) cells to reverse CEACAM-1-dependent inhibition of NK cytotoxicity. Previous studies have demonstrated safety/tolerability in non-human primates, and in a first in human phase 1 clinical trial at the National Cancer Institute (NCI). In addition, preclinical studies have demonstrated that NEO-201 can bind to human regulatory T (Treg) cells. The specificity of NEO-201 in recognizing suppressive Treg cells provides the basis for combination cancer immunotherapy with checkpoint inhibitors targeting the PD-1/PD-L1 pathway.

mRNA-based therapies: Preclinical and clinical applications

At the fundamental level, messenger RNA (mRNA)-based therapeutics involves the delivery of in vitro-transcribed (IVT) mRNA into the cytoplasm of a target cell, where it is translated into the desired protein. IVT mRNA presents various advantages compared to DNA and recombinant protein-based approaches that make it ideal for a broad range of therapeutic applications. IVT mRNA, which is translated in the cytoplasm after transfection into cells, can encode virtually any target protein. Notably, it does not enter the nucleus, which avoids its integration into the genome and the risk of insertional mutagenesis. The large-scale production of IVT mRNA is less complex than production of recombinant proteins, and Good Manufacturing Practice-compliant mRNA production is easily scalable, ideally poising mRNA for not only off-the-shelf, but more personalized treatment approaches. IVT mRNA's safety profile, pharmacokinetics, and pharmacodynamics, including its inherent immunostimulatory capacity, can be optimized for different therapeutic applications by harnessing a wide array of optimized sequence elements, chemical modifications, purification techniques, and delivery methods. The value of IVT mRNA was recently proved during the COVID-19 pandemic when mRNA-based vaccines outperformed the efficacy of established technologies, and millions of doses were rapidly deployed. In this review, we will discuss chemical modifications of IVT mRNA and highlight numerous preclinical and clinical applications including vaccines for cancer and infectious diseases, cancer immunotherapy, protein replacement, gene editing, and cell reprogramming.

Gene-Based Natural Killer Cell Therapies for the Treatment of Pediatric Hematologic Malignancies

Pediatric blood cancers are among the most common malignancies that afflict children. Intensive chemotherapy is not curative in many cases, and novel therapies are urgently needed. NK cells hold promise for use as immunotherapeutic effectors due to their favorable safety profile, intrinsic cytotoxic properties, and potential for genetic modification that can enhance specificity and killing potential. NK cells can be engineered to express CARs targeting tumor-specific antigens, to downregulate inhibitory and regulatory signals, to secrete cytokine, and to optimize interaction with small molecule engagers. Understanding NK cell biology is key to designing immunotherapy for clinical translation.

HIV-1 Reservoir Persistence and Decay: Implications for Cure Strategies

PURPOSE OF REVIEW

Despite suppressive antiretroviral therapy (ART), a viral reservoir persists in individuals living with HIV that can reignite systemic replication should treatment be interrupted. Understanding how HIV-1 persists through effective ART is essential to develop cure strategies to induce ART-free virus remission.

RECENT FINDINGS

The HIV-1 reservoir resides in a pool of CD4-expressing cells as a range of viral species, a subset of which is genetically intact. Recent studies suggest that the reservoir on ART is highly dynamic, with expansion and contraction of virus-infected cells over time. Overall, the intact proviral reservoir declines faster than defective viruses, suggesting enhanced immune clearance or cellular turnover. Upon treatment interruption, rebound viruses demonstrate escape from adaptive and innate immune responses, implicating these selective pressures in restriction of virus reactivation. Cure strategies employing immunotherapy are poised to test whether host immune pressure can be augmented to enhance reservoir suppression or clearance. Alternatively, genomic engineering approaches are being applied to directly eliminate intact viruses and shrink the replication-competent virus pool. New evidence suggests host immunity exerts selective pressure on reservoir viruses and clears HIV-1 infected cells over years on ART. Efforts to build on the detectable, but insufficient, reservoir clearance via empiric testing in clinical trials will inform our understanding of mechanisms of viral persistence and the direction of future cure strategies.

Inhaled recombinant human IL-15 in dogs with naturally occurring pulmonary metastases from osteosarcoma or melanoma: a phase 1 study of clinical activity and correlates of response

PURPOSE

Although recombinant human interleukin-15 (rhIL-15) has generated much excitement as an immunotherapeutic agent for cancer, activity in human clinical trials has been modest to date, in part due to the risks of toxicity with significant dose escalation. Since pulmonary metastases are a major site of distant failure in human and dog cancers, we sought to investigate inhaled rhIL-15 in dogs with naturally occurring lung metastases from osteosarcoma (OSA) or melanoma. We hypothesized a favorable benefit/risk profile given the concentrated delivery to the lungs with decreased systemic exposure.

EXPERIMENTAL DESIGN

We performed a phase I trial of inhaled rhIL-15 in dogs with gross pulmonary metastases using a traditional 3+3 cohort design. A starting dose of 10 µg twice daily × 14 days was used based on human, non-human primate, and murine studies. Safety, dose-limiting toxicities (DLT), and maximum tolerated dose (MTD) were the primary objectives, while response rates, progression-free and overall survival (OS), and pharmacokinetic and immune correlative analyses were secondary.

RESULTS

From October 2018 to December 2020, we enrolled 21 dogs with 18 dogs reaching the 28-day response assessment to be evaluable. At dose level 5 (70 μg), we observed two DLTs, thereby establishing 50 µg twice daily × 14 days as the MTD and recommended phase 2 dose. Among 18 evaluable dogs, we observed one complete response >1 year, one partial response with resolution of multiple target lesions, and five stable disease for an overall clinical benefit rate of 39%. Plasma rhIL-15 quantitation revealed detectable and sustained rhIL-15 concentrations between 1-hour and 6 hour postnebulization. Decreased pretreatment lymphocyte counts were significantly associated with clinical benefit. Cytotoxicity assays of banked peripheral blood mononuclear cells revealed significant increases in peak cytotoxicity against canine melanoma and OSA targets that correlated with OS.

CONCLUSIONS

In this first-in-dog clinical trial of inhaled rhIL-15 in dogs with advanced metastatic disease, we observed promising clinical activity when administered as a monotherapy for only 14 days. These data have significant clinical and biological implications for both dogs and humans with refractory lung metastases and support exploration of combinatorial therapies using inhaled rhIL-15.

2022 update on the scientific premise and clinical trials for IL-15 agonists as cancer immunotherapy

Diverse cytokines and their receptors on immune cells constitute a highly complex network in the immune system. Some therapeutic cytokines and their derivatives have been approved for cancer treatment. IL-15 is an immune-regulating cytokine with multiple functions, among which the function of activating the immunity of cancer patients has great potential in cancer immunotherapy. In this review, we introduce the functions of IL-15 and discuss its role in regulating the immune system in different immune cells. Meanwhile, we will address the applications of IL-15 agonists in cancer immunotherapy and provide prospects for the next generation of therapeutic designs. Although many challenges remain, IL-15 agonists offer a new therapeutic option in the future direction of cancer immunotherapy.

Crosstalk between IL-15Rα+ tumor-associated macrophages and breast cancer cells reduces CD8+ T cell recruitment

Background

Interleukin‐15 (IL‐15) is a promising immunotherapeutic agent owing to its powerful immune‐activating effects. However, the clinical benefits of these treatments are limited. Crosstalk between tumor cells and immune cells plays an important role in immune escape and immunotherapy drug resistance. Herein, this study aimed to obtain in‐depth understanding of crosstalk in the tumor microenvironment for providing potential therapeutic strategies to prevent tumor progression.

Methods

T‐cell killing assays and co‐culture models were developed to determine the role of crosstalk between macrophages and tumor cells in breast cancer resistant to IL‐15. Western blotting, histological analysis, CRISPR‐Cas9 knockout, multi‐parameter flow cytometry, and tumor cell‐macrophage co‐injection mouse models were developed to examine the mechanism by which IL‐15Rα⁺ tumor‐associated macrophages (TAMs) regulate breast cancer cell resistance to IL‐15.

Results

We found that macrophages contributed to the resistance of tumor cells to IL‐15, and tumor cells induced macrophages to express high levels of the α subunit of the IL‐15 receptor (IL‐15Rα). Further investigation showed that IL‐15Rα⁺ TAMs reduced the protein levels of chemokine CX3C chemokine ligand 1 (CX3CL1) in tumor cells to inhibit the recruitment of CD8⁺ T cells by releasing the IL‐15/IL‐15Rα complex (IL‐15Rc). Administration of an IL‐15Rc blocking peptide markedly suppressed breast tumor growth and overcame the resistance of cancer cells to anti‐ programmed cell death protein 1 (PD‐1) antibody immunotherapy. Interestingly, Granulocyte‐macrophage colony‐stimulating factor (GMCSF) induced γ chain (γc) expression to promote tumor cell‐macrophage crosstalk, which facilitated tumor resistance to IL‐15. Additionally, we observed that the non‐transcriptional regulatory function of hypoxia inducible factor‐1alpha (HIF‐1α) was essential for IL‐15Rc to regulate CX3CL1 expression in tumor cells.

Conclusions

The IL‐15Rc‐HIF‐1α‐CX3CL1 signaling pathway serves as a crosstalk between macrophages and tumor cells in the tumor microenvironment of breast cancer. Targeting this pathway may provide a potential therapeutic strategy for enhancing the efficacy of cancer immunotherapy.

Natural killer cells: a promising immunotherapy for cancer

As a promising alternative platform for cellular immunotherapy, natural killer cells (NK) have recently gained attention as an important type of innate immune regulatory cell. NK cells can rapidly kill multiple adjacent cancer cells through non-MHC-restrictive effects. Although tumors may develop multiple resistance mechanisms to endogenous NK cell attack, in vitro activation, expansion, and genetic modification of NK cells can greatly enhance their anti-tumor activity and give them the ability to overcome drug resistance. Some of these approaches have been translated into clinical applications, and clinical trials of NK cell infusion in patients with hematological malignancies and solid tumors have thus far yielded many encouraging clinical results. CAR-T cells have exhibited great success in treating hematological malignancies, but their drawbacks include high manufacturing costs and potentially fatal toxicity, such as cytokine release syndrome. To overcome these issues, CAR-NK cells were generated through genetic engineering and demonstrated significant clinical responses and lower adverse effects compared with CAR-T cell therapy. In this review, we summarize recent advances in NK cell immunotherapy, focusing on NK cell biology and function, the types of NK cell therapy, and clinical trials and future perspectives on NK cell therapy.

IL15 and Anti-PD-1 Augment the Efficacy of Agonistic Intratumoral Anti-CD40 in a Mouse Model with Multiple TRAMP-C2 Tumors

PURPOSE

IL15 promotes activation and maintenance of natural killer (NK) and CD8+ T effector memory cells making it a potential immunotherapeutic agent for the treatment of cancer. However, monotherapy with IL15 was ineffective in patients with cancer, indicating that it would have to be used in combination with other anticancer agents. The administration of high doses of common gamma chain cytokines, such as IL15, is associated with the generation of "helpless" antigen-nonspecific CD8 T cells. The generation of the tumor-specific cytotoxic T cells can be mediated by CD40 signaling via agonistic anti-CD40 antibodies. Nevertheless, parenteral administration of anti-CD40 antibodies is associated with unacceptable side effects, such as thrombocytopenia and hepatic toxicity, which can be avoided by intratumoral administration.

EXPERIMENTAL DESIGN

We investigated the combination of IL15 with an intratumoral anti-CD40 monoclonal antibody (mAb) in a dual tumor TRAMP-C2 murine prostate cancer model and expanded the regimen to include an anti-PD-1 mAb.

RESULTS

Here we demonstrated that anti-CD40 given intratumorally not only showed significant antitumor activity in treated tumors, but also noninjected contralateral tumors, indicative of abscopal efficacy. The combination of IL15 with intratumoral anti-CD40 showed an additive immune response with an increase in the number of tumor-specific tetramer-positive CD8 T cells. Furthermore, the addition of anti-PD-1 further improved efficacy mediated by the anti-CD40/IL15 combination.

CONCLUSIONS

These studies support the initiation of a clinical trial in patients with cancer using IL15 in association with the checkpoint inhibitor, anti-PD-1, and intratumoral optimized anti-CD40.

Interleukin-15 augments NK cell-mediated ADCC of alemtuzumab in patients with CD52+ T-cell malignancies

Interleukin-15 (IL-15) monotherapy substantially increases the number and activity of natural killer (NK) cells and CD8+ T cells but has not produced clinical responses. In a xenograft mouse model, IL-15 enhanced the NK cell-mediated antibody-dependent cell cytotoxicity (ADCC) of the anti-CD52 antibody alemtuzumab and led to significantly more durable responses than alemtuzumab alone. To evaluate whether IL-15 potentiates ADCC in humans, we conducted a phase 1 single-center study of recombinant human IL-15 and alemtuzumab in patients with CD52-positive mature T-cell malignances. We gave IL-15 subcutaneously 5 days per week for 2 weeks in a 3 + 3 dose escalation scheme (at 0.5, 1, and 2 μg/kg), followed by standard 3 times weekly alemtuzumab IV for 4 weeks. There were no dose-limiting toxicities or severe adverse events attributable to IL-15 in the 11 patients treated. The most common adverse events were lymphopenia (100%), alemtuzumab-related infusion reactions (90%), anemia (90%), and neutropenia (72%). There were 3 partial and 2 complete responses, with an overall response rate of 45% and median duration of response 6 months. Immediately after 10 days of IL-15, there was a median 7.2-fold increase in NK cells and 2.5-fold increase in circulating CD8+ T cells, whereas the number of circulating leukemic cells decreased by a median 38% across all dose levels. Treatment with IL-15 was associated with increased expression of NKp46 and NKG2D, markers of NK-cell activation, and increased ex vivo ADCC activity of NK cells, whereas inhibitory receptors PD1 and Tim3 were decreased. This trial was registered at www.clinicaltrials.gov as #NCT02689453.

A novel multifunctional anti-PD-L1-CD16a-IL15 induces potent cancer cell killing in PD-L1-positive tumour cells

•

Anti-PD-L1 single-domain antibodies were identified from hPD-L1-immunized camels.

•

Three novel multifunctional antibodies, anti-PD-L1-CD16a, anti-PD-L1-IL15, and anti-PD-L1-CD16a-IL15, target PD-L1-positive cancer cells.

•

Anti-PD-L1-IL15 and anti-PD-L1-CD16a-IL15, but not anti-PD-L1-CD16a, stimulate immune cell proliferation in vitro.

•

The anti-PD-L1 antibodies can bind PD-L1-positive cells.

•

Anti-PD-L1-CD16a-IL15 has the strongest antitumour activity, both in vitro and in vivo.

Cancer is the most acute disease and the leading cause of patient death worldwide. Both chemotherapy and molecular-based therapies play an important role in curing cancer. However, the median and overall survival of patients is poor. To date, immune therapies have changed the treatment methods for cancer patients. Programmed death ligand 1 (PD-L1, also known as B-H1, CD274) is a well-studied tumor antigen. PD-L1 is overexpressed in colon cancer, lung cancer, and so on and plays a vital role in cancer development. In this study, anti-PD-L1 single-domain antibodies were identified from recombinant human PD-L1 (rhPD-L1)-immunized llamas. Then, we generated a novel multifunctional anti-PD-L1-CD16a-IL15 antibody targeting PD-L1-positive tumor cells. Anti-PD-L1-CD16a-IL15 was constructed by linking the Interleukin-2 (IL-2) signal peptide, anti-PD-L1 single domain antibody (anti-PD-L1-VHH) and anti-cluster of differentiation 16a single domain antibody (anti-CD16a-VHH), and Interleukin-15/Interleukin-15 receptor alpha (IL15/IL-15Rα). This anti-PD-L1-CD16a-IL15 fusion protein can be expressed and purified from HEK-293F cells. In vitro, our data showed that the anti-PD-L1-CD16a-IL15 fusion protein can recruit T cells and drive natural killer cells (NK) with specific killing of PD-L1-overexpressing tumor cells. Furthermore, in the xenograft model, the anti-PD-L1-CD16a-IL15 fusion protein inhibited tumor growth with human peripheral blood mononuclear cells (PBMCs). These data suggested that the anti-PD-L1-CD16a-IL15 fusion protein has a latent function in antitumour activity, with better guidance for future cancer immunotherapy.

Physical Exercise Restrains Cancer Progression through Muscle-Derived Factors

Simple Summary

The benefits of physical exercise against cancer onset and progression, as well as the adverse effects of physical inactivity have changed the way that we utilize exercise for cancer patients. Nevertheless, although guidelines of various scientific societies and organizations propose exercise as a complementary intervention during cancer therapies, the exact cellular and molecular mechanisms by which exercise acts against cancer have not yet been elucidated. In the present review, we analyze the factors which either are secreted from skeletal muscle or are regulated by exercise and can restrain cancer evolution. We also describe the exercise-induced factors that counteract severe side effects of cancer treatment, as well as the ways that muscle-derived factors are delivered to the target cells.

Abstract

A growing body of in vitro and in vivo studies suggests that physical activity offers important benefits against cancer, in terms of both prevention and treatment. However, the exact mechanisms implicated in the anticancer effects of exercise remain to be further elucidated. Muscle-secreted factors in response to contraction have been proposed to mediate the physical exercise-induced beneficial effects and be responsible for the inter-tissue communications. Specifically, myokines and microRNAs (miRNAs) constitute the most studied components of the skeletal muscle secretome that appear to affect the malignancy, either directly by possessing antioncogenic properties, or indirectly by mobilizing the antitumor immune responses. Moreover, some of these factors are capable of mitigating serious, disease-associated adverse effects that deteriorate patients’ quality of life and prognosis. The present review summarizes the myokines and miRNAs that may have potent anticancer properties and the expression of which is induced by physical exercise, while the mechanisms of secretion and intercellular transportation of these factors are also discussed.

Delivery of CAR-T cells in a transient injectable stimulatory hydrogel niche improves treatment of solid tumors

Adoptive cell therapy (ACT) has proven to be highly effective in treating blood cancers, but traditional approaches to ACT are poorly effective in treating solid tumors observed clinically. Novel delivery methods for therapeutic cells have shown promise for treatment of solid tumors when compared with standard intravenous administration methods, but the few reported approaches leverage biomaterials that are complex to manufacture and have primarily demonstrated applicability following tumor resection or in immune-privileged tissues. Here, we engineer simple-to-implement injectable hydrogels for the controlled co-delivery of CAR-T cells and stimulatory cytokines that improve treatment of solid tumors. The unique architecture of this material simultaneously inhibits passive diffusion of entrapped cytokines and permits active motility of entrapped cells to enable long-term retention, viability, and activation of CAR-T cells. The generation of a transient inflammatory niche following administration affords sustained exposure of CAR-T cells, induces a tumor-reactive CAR-T phenotype, and improves efficacy of treatment.

Harnessing cytokines and chemokines for cancer therapy

During the past 40 years, cytokines and cytokine receptors have been extensively investigated as either cancer targets or cancer treatments. A strong preclinical rationale supports therapeutic strategies to enhance the growth inhibitory and immunostimulatory effects of interferons and interleukins, including IL-2, IL-7, IL-12 and IL-15, or to inhibit the inflammatory and tumour-promoting actions of cytokines such as TNF, IL-1β and IL-6. This rationale is underscored by the discovery of altered and dysregulated cytokine expression in all human cancers. These findings prompted clinical trials of several cytokines or cytokine antagonists, revealing relevant biological activity but limited therapeutic efficacy. However, most trials involved patients with advanced-stage disease, which might not be the optimal setting for cytokine-based therapy. The advent of more effective immunotherapies and an increased understanding of the tumour microenvironment have presented new approaches to harnessing cytokine networks in the treatment of cancer, which include using cytokine-based therapies to enhance the activity or alleviate the immune-related toxicities of other treatments as well as to target early stage cancers. Many challenges remain, especially concerning delivery methods, context dependencies, and the pleiotropic, redundant and often conflicting actions of many cytokines. Herein, we discuss the lessons learnt from the initial trials of single-agent cytokine-based therapies and subsequent efforts to better exploit such agents for the treatment of solid tumours.

Phase I Trial Characterizing the Pharmacokinetic Profile of N-803, a Chimeric IL-15 Superagonist, in Healthy Volunteers

The oncotherapeutic promise of IL-15, a potent immunostimulant, is limited by a short serum t 1/2 The fusion protein N-803 is a chimeric IL-15 superagonist that has a >20-fold longer in vivo t 1/2 versus IL-15. This phase 1 study characterized the pharmacokinetic (PK) profile and safety of N-803 after s.c. administration to healthy human volunteers. Volunteers received two doses of N-803, and after each dose, PK and safety were assessed for 9 d. The primary endpoint was the N-803 PK profile, the secondary endpoint was safety, and immune cell levels and immunogenicity were measures of interest. Serum N-803 concentrations peaked 4 h after administration and declined with a t 1/2 of ∼20 h. N-803 did not cause treatment-emergent serious adverse events (AEs) or grade ≥3 AEs. Injection site reactions, chills, and pyrexia were the most common AEs. Administration of N-803 was well tolerated and accompanied by proliferation of NK cells and CD8+ T cells and sustained increases in the number of NK cells. Our results suggest that N-803 administration can potentiate antitumor immunity.

iNKT: A new avenue for CAR-based cancer immunotherapy

Chimeric antigen receptor (CAR) T cell is a T lymphocyte-based immunotherapy, which achieves great successes in treating blood malignancies and provides new hope to cue advanced cancer patients. Invariant natural killer T (iNKT) cells are a kind of special T lymphocytes characterized by expressing invariant TCR of Vα24Vβ11 to recognize CD1d-presented glycolipid antigens, which bridge innate and adaptive immune responses. iNKT cells themselves show strong anti-tumor effect in tumor models via CD1d-mediated killing of CD1d-positive tumor cells and immunosuppressive TAMs and MDSCs, and are closely related to the prognosis of cancer patients. iNKT cells are not restricted to polymorphic human leukocyte antigen (HLA) and can prevent Graft versus Host Disease (GvHD), which makes it to be an ideal CAR vector for allogeneic therapy. Although CAR-iNKT was developed and verified by several different teams and attracts more and more attentions, many obstacles are still needed to be resolved before obtaining CAR-iNKT therapeutics. In this review, we summarized the current status of clinical application of iNKT cells and the latest achievements of CAR-iNKT cells, which provides new insight in CAR-iNKT development and usages.

Engineering interferons and interleukins for cancer immunotherapy

Cytokines are a class of potent immunoregulatory proteins that are secreted in response to various stimuli and act locally to regulate many aspects of human physiology and disease. Cytokines play important roles in cancer initiation, progression, and elimination, and thus, there is a long clinical history associated with the use of recombinant cytokines to treat cancer. However, the use of cytokines as therapeutics has been limited by cytokine pleiotropy, complex biology, poor drug-like properties, and severe dose-limiting toxicities. Nevertheless, cytokines are crucial mediators of innate and adaptive antitumor immunity and have the potential to enhance immunotherapeutic approaches to treat cancer. Development of immune checkpoint inhibitors and combination immunotherapies has reinvigorated interest in cytokines as therapeutics, and a variety of engineering approaches are emerging to improve the safety and effectiveness of cytokine immunotherapy. In this review we highlight recent advances in cytokine biology and engineering for cancer immunotherapy.

Systemic IL-15 promotes allogeneic cell rejection in patients treated with natural killer cell adoptive therapy

Natural killer (NK) cells are a promising alternative to T cells for cancer immunotherapy. Adoptive therapies with allogeneic, cytokine-activated NK cells are being investigated in clinical trials. However, the optimal cytokine support after adoptive transfer to promote NK cell expansion, and persistence remains unclear. Correlative studies from 2 independent clinical trial cohorts treated with major histocompatibility complex-haploidentical NK cell therapy for relapsed/refractory acute myeloid leukemia revealed that cytokine support by systemic interleukin-15 (IL-15; N-803) resulted in reduced clinical activity, compared with IL-2. We hypothesized that the mechanism responsible was IL-15/N-803 promoting recipient CD8 T-cell activation that in turn accelerated donor NK cell rejection. This idea was supported by increased proliferating CD8+ T-cell numbers in patients treated with IL-15/N-803, compared with IL-2. Moreover, mixed lymphocyte reactions showed that IL-15/N-803 enhanced responder CD8 T-cell activation and proliferation, compared with IL-2 alone. Additionally, IL-15/N-803 accelerated the ability of responding T cells to kill stimulator-derived memory-like NK cells, demonstrating that additional IL-15 can hasten donor NK cell elimination. Thus, systemic IL-15 used to support allogeneic cell therapy may paradoxically limit their therapeutic window of opportunity and clinical activity. This study indicates that stimulating patient CD8 T-cell allo-rejection responses may critically limit allogeneic cellular therapy supported with IL-15. This trial was registered at www.clinicaltrials.gov as #NCT03050216 and #NCT01898793.

Treatment-related lymphopenia impairs the treatment response of anti-PD-1 therapy in esophageal squamous cell carcinoma

PURPOSE

Great interest has been focused on radiotherapy (RT) with immunotherapy. We sought to investigate the significance of treatment-related lymphopenia (TRL) in esophageal squamous cell carcinoma (ESCC) patients receiving anti-PD-1 therapy and the factors associated with TRL, especially RT.

METHODS

167 patients with ESCC that received anti-PD-1 therapy wereidentified, 72 of them received RT. TRL was defined as absolute lymphocyte count (ALC) < 0.50 × 10⁹ cells/L at the start of immunotherapy and/or during immunotherapy. Depending on the presence of TRL, patients were divided into two groups.

RESULTS

At median follow-up of 6.5 months, the ORR of patients without TRL (n = 65; 38.9%) reached 29.4% while patients (n = 102; 61.1%) with TRL was 23.1%, DCR was 81.4% and 75.4% respectively. Patients with TRL showed shorter progression-free survival (PFS) compared with patients without TRL (median PFS: 4.8 vs. 7.0 months, P = 0.009). Multivariate analyses confirmed TRL is an independent prognostic factor for poorer PFS (HR, 1.855; P = 0.008). RT significantly increased the occurrence of TRL (OR = 0.502, P = 0.035). Patients receiving ICIs < 33.5 days after RT showed a poorer PFS compared to that ≥ 33.5 days (median PFS: 4.1 vs 7.3 months, P = 0.008). The explanation is that patients with shorter time interval had a higher incidence of TRL (P = 0.028).

CONCLUSION

TRL was an independent predictor of poor outcomes in ESCC patients receiving anti-PD-1 therapy. RT was a key factor affecting TRL. A shorter time interval of < 33.5 days between RT and anti-PD-1 therapy can lead to a poor prognosis by increasing the occurrence of TRL.

Synergistic effect of Abraxane that combines human IL15 fused with an albumin-binding domain on murine models of pancreatic ductal adenocarcinoma

Nab‐paclitaxel (Abraxane), which is a nanoparticle form of albumin‐bound paclitaxel, is one of the standard chemotherapies for pancreatic ductal adenocarcinoma (PDAC). This study determined the effect of Abraxane in combination with a fusion protein, hIL15‐ABD, on subcutaneous Panc02 and orthotopic KPC C57BL/6 murine PDAC models. Abraxane combined with hIL15‐ABD best suppressed tumour growth and produced a 40%–60% reduction in the tumour size for Panc02 and KPC, compared to the vehicle group. In the combination group, the active form of interferon‐γ (IFN‐γ)‐secreting CD8⁺ T cells and CD11b⁺CD86⁺ M1 macrophages in tumour infiltrating lymphocytes (TILs) were increased. In the tumour drainage lymph nodes (TDLNs) of the combination group, there was a 18% reduction in CD8⁺IFN‐γ⁺ T cells and a 0.47% reduction in CD4⁺CD25⁺FOXP3⁺ regulatory T cells, as opposed to 5.0% and 5.1% reductions, respectively, for the control group. Superior suppression of CD11b⁺GR‐1⁺ myeloid‐derived suppressor cells (MDSCs) and the induction of M1 macrophages in the spleen and bone marrow of mice were found in the combination group. Abraxane and hIL15‐ABD effectively suppressed NF‐κB‐mediated immune suppressive markers, including indoleamine 2,3‐dioxygenase (IDO), Foxp3 and VEGF. In conclusion, Abraxane combined with hIL15‐ABD stimulates the anticancer activity of effector cells, inhibits immunosuppressive cells within the tumour microenvironment (TME) of PDAC, and produces a greater inhibitory effect than individual monotherapies.

New Developments in T Cell Immunometabolism and Implications for Cancer Immunotherapy

Despite rapid advances in the field of immunotherapy, the elimination of established tumors has not been achieved. Many promising new treatments such as adoptive cell therapy (ACT) fall short, primarily due to the loss of T cell effector function or the failure of long-term T cell persistence. With the availability of new tools and advancements in technology, our understanding of metabolic processes has increased enormously in the last decade. Redundancy in metabolic pathways and overlapping targets that could address the plasticity and heterogenous phenotypes of various T cell subsets have illuminated the need for understanding immunometabolism in the context of multiple disease states, including cancer immunology. Herein, we discuss the developing field of T cell immunometabolism and its crucial relevance to improving immunotherapeutic approaches. This in-depth review details the metabolic pathways and preferences of the antitumor immune system and the state of various metabolism-targeting therapeutic approaches.

Sarcopenia and risk of infection in adult heart transplant recipients in Japan

AIMS

Heart transplantation (HT) is an effective therapeutic option for end-stage heart failure. Infection is a major cause of morbidity and mortality after HT. Sarcopenia, defined as the loss of muscle mass and strength, is a common comorbidity in HT candidates with end-stage heart failure. However, the effects of sarcopenia on the occurrence of post-HT infections are not well understood. Therefore, we explored the association between the skeletal muscle mass and post-transplant infections in adult HT recipients.

METHODS AND RESULTS

We retrospectively examined the records of 135 patients who underwent HT between August 2007 and November 2019 at our institution. Pre-transplant computed tomography was used to calculate the skeletal muscle index (SMI) at the level of the third lumbar vertebra. Muscle wasting was defined as the SMI of the lowest sex-based tertiles. The primary endpoint was infections within 6 months of HT. The study included 109 patients (80 men, mean age: 41.6 ± 12.0 years): 37 patients in the muscle wasting group and 72 patients in the non-muscle wasting group. The mean SMI values in the muscle wasting and non-muscle wasting groups were 29.9 ± 4.8 cm² /m² and 40.7 ± 6.7 cm² /m² , respectively. Prior to HT, 108 (99.1%) patients were on left ventricular assist device support, and during that support, the rate of late right heart failure was significantly higher in the muscle wasting group than non-muscle wasting group (P = 0.012). Sixteen infections occurred within 6 months of HT. The most common infection sites included the respiratory tract (n = 5) and the upper gastrointestinal tract (n = 5), followed by the urinary tract (n = 4). Overall, 10 patients experienced infections in the muscle wasting group (27.0%) and 6 in the non-muscle wasting group (8.3%) (P = 0.009). Two patients in the muscle wasting group required intensive care unit admission, compared to none in the non-muscle wasting group. Low skeletal muscle mass was associated with infections in the univariate and multivariate logistic regression models (hazard ratio: 3.68, 95% confidence interval: 1.19-11.3; P = 0.023). However, the duration of all-cause mortality within 3 years did not differ between the groups (P = 0.56).

CONCLUSIONS

Low skeletal muscle mass is a predictor of post-HT infections within 6 months of HT.

The War Is on: The Immune System against Glioblastoma—How Can NK Cells Drive This Battle?

Natural killer (NK) cells are innate lymphocytes that play an important role in immunosurveillance, acting alongside other immune cells in the response against various types of malignant tumors and the prevention of metastasis. Since their discovery in the 1970s, they have been thoroughly studied for their capacity to kill neoplastic cells without the need for previous sensitization, executing rapid and robust cytotoxic activity, but also helper functions. In agreement with this, NK cells are being exploited in many ways to treat cancer. The broad arsenal of NK-based therapies includes adoptive transfer of in vitro expanded and activated cells, genetically engineered cells to contain chimeric antigen receptors (CAR-NKs), in vivo stimulation of NK cells (by cytokine therapy, checkpoint blockade therapies, etc.), and tumor-specific antibody-guided NK cells, among others. In this article, we review pivotal aspects of NK cells’ biology and their contribution to immune responses against tumors, as well as providing a wide perspective on the many antineoplastic strategies using NK cells. Finally, we also discuss those approaches that have the potential to control glioblastoma—a disease that, currently, causes inevitable death, usually in a short time after diagnosis.

Engineering CAR-NK cells: how to tune innate killer cells for cancer immunotherapy

Cell therapy is an innovative approach that permits numerous possibilities in the field of cancer treatment. CAR-T cells have been successfully used in patients with hematologic relapsed/refractory. However, the need for autologous sources for T cells is still a major drawback. CAR-NK cells have emerged as a promising resource using allogeneic cells that could be established as an off-the-shelf treatment. NK cells can be obtained from various sources, such as peripheral blood (PB), bone marrow, umbilical cord blood (CB), and induced pluripotent stem cells (iPSC), as well as cell lines. Genetic engineering of NK cells to express different CAR constructs for hematological cancers and solid tumors has shown promising preclinical results and they are currently being explored in multiple clinical trials. Several strategies have been employed to improve CAR-NK-cell expansion and cytotoxicity efficiency. In this article, we review the latest achievements and progress made in the field of CAR-NK-cell therapy.

Physical exercise at the crossroad between muscle wasting and the immune system: implications for lung cancer cachexia

Cachexia is a syndrome characterized by involuntary weight loss and wasting of skeletal muscle mass. It is associated with worse overall survival and quality of life. The cancer-induced systemic inflammation and the consequent host derived catabolic stimuli, trigger cachexia by inhibiting muscle protein synthesis and enhancing muscle catabolism. The muscle itself may further promote chronic inflammation, introducing a vicious catabolic circle. Nutritional support alone plays a limited role in the treatment of cancer cachexia and should be combined with other interventions. Physical exercise lowers systemic inflammation and promotes muscle anabolism. It also attenuates the age-related physical decline in elderly and it might counteract the muscle wasting induced by the cancer cachexia syndrome. This review describes how cancer-induced systemic inflammation promotes muscle wasting and whether physical exercise may represent a suitable treatment for cancer-induced cachexia, particularly in patients with non-small cell lung cancer. We summarized pre-clinical and clinical studies investigating whether physical exercise would improve muscle performance and whether this improvement would translate in a clinically meaningful benefit for patients with cancer, in terms of survival and quality of life. Moreover, this review describes the results of studies investigating the interplay between physical exercise and the immune system, including the role of the intestinal microbiota.

Inflammation and Myeloid Cells in Cancer Progression and Metastasis

To date, the most immunotherapy drugs act upon T cell surface proteins to promote tumoricidal T cell activity. However, this approach has to date been unsuccessful in certain solid tumor types including pancreatic, prostate cancer and glioblastoma. Myeloid-related innate immunity can promote tumor progression through direct and indirect effects on T cell activity; improved understanding of this field may provide another therapeutic avenue for patients with these tumors. Myeloid cells can differentiate into both pro-inflammatory and anti-inflammatory mature form depending upon the microenvironment. Most cancer type exhibit oncogenic activating point mutations (ex. P53 and KRAS) that trigger cytokines production. In addition, tumor environment (ex. Collagen, Hypoxia, and adenosine) also regulated inflammatory signaling cascade. Both the intrinsic and extrinsic factor driving the tumor immune microenvironment and regulating the differentiation and function of myeloid cells, T cells activity and tumor progression. In this review, we will discuss the relationship between cancer cells and myeloid cells-mediated tumor immune microenvironment to promote cancer progression and immunotherapeutic resistance. Furthermore, we will describe how cytokines and chemokines produced by cancer cells influence myeloid cells within immunosuppressive environment. Finally, we will comment on the development of immunotherapeutic strategies with respect to myeloid-related innate immunity.

Immune System in Action

Tumor exists as a complex network of structures with an ability to evolve and evade the host immune surveillance mechanism. The immune milieu which includes macrophages, dendritic cells, natural killer cells, neutrophils, mast cells, B cells, and T cells is found in the core, the invasive margin, or the adjacent stromal or lymphoid component of the tumor. The immune infiltrate is heterogeneous and varies within a patient and between patients of the same tumor histology. The location, density, functionality, and the crosstalk between the immune cells in the tumor microenvironment influence the nature of immune response, prognosis, and treatment outcomes in cancer patients. Therefore, an understanding of the characteristics of the immune cells and their role in tumor immune surveillance is of paramount importance to identify immune targets and to develop novel immune therapeutics in the war against cancer. In this chapter, we provide an overview of the individual components of the human immune system and the translational relevance of predictive biomarkers.

Combination therapy with Nab-paclitaxel and the interleukin-15 fused with anti-human serum albumin nanobody as a synergistic treatment for colorectal cancer

This study determines the effect of Nab-paclitaxel in combination with IL-15 fusion protein, containing IL-15 and an anti-HSA nanobody domain, on colorectal cancer bearing mice. In vitro binding test of IL15 fusion protein to HSA and Nab-paclitaxel, as well as CTLL-2 cell stimulation assay were performed. The tumor inhibitory effects of Nab-paclitaxel in combination with IL-15 fusion protein was evaluated in the HCT116 bearing murine model. Moreover, the population and function of cytotoxic T cells and M1 macrophages, as well as MDSCs and Treg cells, were also further examined. As a result, combination therapy of Nab-paclitaxel and IL-15 fusion protein effectively inhibits the tumor growth and produced a 78% reduction in tumor size for HCT116, as compared to vehicle group. In the TDLN for the combination group, there were 18% of CD8+ IFN-γ + T-cells and 0.47% CD4⁺CD25⁺FOXP3⁺ regulatory T-cells, as opposed to 5.0% and 5.1%, respectively, for the model control group. Combination therapy further exhibited enhanced suppressive effects on the accumulation of CD11b⁺GR-1⁺ MDSC in spleen and bone marrow. Furthermore, Nab-paclitaxel and IL-15 fusion protein showed a significant suppression of NF-κB-mediated immune suppressive markers and increased expression of CD8, Granzyme B, CD62L, CD49b, and CD86 without obvious organ toxicity. In conclusion, combination therapy of Nab-paclitaxel and IL-15 fusion protein can effectively stimulate the antitumor activity of immune effector cells, thereby inhibiting immunosuppressive cells within the TME of colorectal cancer, and the overall therapeutic effect has a significant advantage over monotherapy.AbbreviationsInterleukin 15, IL-15; Human serum albumin, HSA; Myeloid-derived suppressor cells, MDSC; Albumin binding domain, ABD; Tumor drainage lymph node, TDLN; Natural killer (NK); Tumor-draining lymph node (TDLN); Tumor infiltrating lymphocyte, TIL; Immunogenic cell death, ICD; Enhanced permeability retention, EPR; Liposomal doxorubicin, Doxil; 5-fluorouracil, 5-FU.

A very long-acting IL-15: implications for the immunotherapy of cancer

BACKGROUND

Interleukin-15 (IL-15) is an important cytokine necessary for proliferation and maintenance of natural killer (NK) and CD8+ T cells, and with great promise as an immuno-oncology therapeutic. However, IL-15 has a very short half-life and a single administration does not provide the sustained exposure required for optimal stimulation of target immune cells. The purpose of this work was to develop a very long-acting prodrug that would maintain IL-15 within a narrow therapeutic window for long periods-similar to a continuous infusion.

METHODS

We prepared and characterized hydrogel microspheres (MS) covalently attached to IL-15 (MS~IL-15) by a releasable linker. The pharmacokinetics and pharmacodynamics of MS~IL-15 were determined in C57BL/6J mice. The antitumor activity of MS~IL-15 as a single agent, and in combination with a suitable therapeutic antibody, was tested in a CD8+ T cell-driven bilateral transgenic adenocarcinoma mouse prostate (TRAMP)-C2 model of prostatic cancer and a NK cell-driven mouse xenograft model of human ATL (MET-1) murine model of adult T-cell leukemia.

RESULTS

On subcutaneous administration to mice, the cytokine released from the depot maintained a long half-life of about 168 hours over the first 5 days, followed by an abrupt decrease to about ~30 hours in accordance with the development of a cytokine sink. A single injection of MS~IL-15 caused remarkably prolonged expansions of NK and ɣδ T cells for 2 weeks, and CD44hiCD8+ T cells for 4 weeks. In the NK cell-driven MET-1 murine model of adult T-cell leukemia, single-agent MS~IL-1550 μg or anti-CCR4 provided modest increases in survival, but a combination-through antibody-depedent cellular cytotoxicity (ADCC)-significantly extended survival. In a CD8+ T cell-driven bilateral TRAMP-C2 model of prostatic cancer, single agent subcutaneous MS~IL-15 or unilateral intratumoral agonistic anti-CD40 showed modest growth inhibition, but the combination exhibited potent, prolonged bilateral antitumor activity.

CONCLUSIONS

Our results show MS~IL-15 provides a very long-acting IL-15 with low Cmax that elicits prolonged expansion of target immune cells and high anticancer activity, especially when administered in combination with a suitable immuno-oncology agent.

Importance of T, NK, CAR T and CAR NK Cell Metabolic Fitness for Effective Anti-Cancer Therapy: A Continuous Learning Process Allowing the Optimization of T, NK and CAR-Based Anti-Cancer Therapies

Simple Summary

Cancer treatments are evolving at a very rapid pace. Some of the most novel anti-cancer medicines under development rely on the modification of immune cells in order to transform them into potent tumor-killing cells. However, the tumor microenvironment (TME) is competing for nutrients with these harnessed immune cells and therefore paralyzes their metabolic effective and active anti-cancer activities. Here we describe strategies to overcome these hurdles imposed on immune cell activity, which lead to therapeutic approaches to enhance metabolic fitness of the patient’s immune system with the objective to improve their anti-cancer capacity.

Abstract

Chimeric antigen receptor (CAR) T and CAR NK cell therapies opened new avenues for cancer treatment. Although original successes of CAR T and CAR NK cells for the treatment of hematological malignancies were extraordinary, several obstacles have since been revealed, in particular their use for the treatment of solid cancers. The tumor microenvironment (TME) is competing for nutrients with T and NK cells and their CAR-expressing counterparts, paralyzing their metabolic effective and active states. Consequently, this can lead to alterations in their anti-tumoral capacity and persistence in vivo. High glucose uptake and the depletion of key amino acids by the TME can deprive T and NK cells of energy and building blocks, which turns them into a state of anergy, where they are unable to exert cytotoxic activity against cancer cells. This is especially true in the context of an immune-suppressive TME. In order to re-invigorate the T, NK, CAR T and CAR NK cell-mediated antitumor response, the field is now attempting to understand how metabolic pathways might change T and NK responses and functions, as well as those from their CAR-expressing partners. This revealed ways to metabolically rewire these cells by using metabolic enhancers or optimizing pre-infusion in vitro cultures of these cells. Importantly, next-generation CAR T and CAR NK products might include in the future the necessary metabolic requirements by improving their design, manufacturing process and other parameters. This will allow the overcoming of current limitations due to their interaction with the suppressive TME. In a clinical setting, this might improve their anti-cancer effector activity in synergy with immunotherapies. In this review, we discuss how the tumor cells and TME interfere with T and NK cell metabolic requirements. This may potentially lead to therapeutic approaches that enhance the metabolic fitness of CAR T and CAR NK cells, with the objective to improve their anti-cancer capacity.

IL-15Rα-Independent IL-15 Signaling in Non-NK Cell-Derived IFNγ Driven Control of Listeria monocytogenes

Interleukin-15, produced by hematopoietic and parenchymal cells, maintains immune cell homeostasis and facilitates activation of lymphoid and myeloid cell subsets. IL-15 interacts with the ligand-binding receptor chain IL-15Rα during biosynthesis, and the IL-15:IL-15Rα complex is trans-presented to responder cells that express the IL-2/15Rβγ_c complex to initiate signaling. IL-15-deficient and IL-15Rα-deficient mice display similar alterations in immune cell subsets. Thus, the trimeric IL-15Rαβγ_c complex is considered the functional IL-15 receptor. However, studies on the pathogenic role of IL-15 in inflammatory and autoimmune diseases indicate that IL-15 can signal independently of IL-15Rα via the IL-15Rβγ_c dimer. Here, we compared the ability of mice lacking IL-15 (no signaling) or IL-15Rα (partial/distinct signaling) to control Listeria monocytogenes infection. We show that IL-15-deficient mice succumb to infection whereas IL-15Rα-deficient mice clear the pathogen as efficiently as wildtype mice. IL-15-deficient macrophages did not show any defect in bacterial uptake or iNOS expression in vitro. In vivo, IL-15 deficiency impaired the accumulation of inflammatory monocytes in infected spleens without affecting chemokine and pro-inflammatory cytokine production. The inability of IL-15-deficient mice to clear L. monocytogenes results from impaired early IFNγ production, which was not affected in IL-15Rα-deficient mice. Administration of IFNγ partially enabled IL-15-deficient mice to control the infection. Bone marrow chimeras revealed that IL-15 needed for early bacterial control can originate from both hematopoietic and non-hematopoietic cells. Overall, our findings indicate that IL-15-dependent IL-15Rα-independent signaling via the IL-15Rβγ_c dimeric complex is necessary and sufficient for the induction of IFNγ from sources other than NK/NKT cells to control bacterial pathogens.

Challenges and Recent Advances in NK Cell-Targeted Immunotherapies in Solid Tumors

Natural killer (NK) cell is a powerful malignant cells killer, providing rapid immune responses via direct cytotoxicity without the need of antigen processing and presentation. It plays an essential role in preventing early tumor, metastasis and minimal residual disease. Although adoptive NK therapies achieved great success in clinical trials against hematologic malignancies, their accumulation, activation, cytotoxic and immunoregulatory functions are severely impaired in the immunosuppressive microenvironment of solid tumors. Now with better understandings of the tumor evasive mechanisms from NK-mediated immunosurveillance, immunotherapies targeting the key molecules for NK cell dysfunction and exhaustion have been developed and tested in both preclinical and clinical studies. In this review, we introduce the challenges that NK cells encountered in solid tumor microenvironment (TME) and the therapeutic approaches to overcome these limitations, followed by an outline of the recent preclinical advances and the latest clinical outcomes of NK-based immunotherapies, as well as promising strategies to optimize current NK-targeted immunotherapies for solid tumors.

Expression of immune-related genes as prognostic biomarkers for the assessment of osteosarcoma clinical outcomes

Cancer immunotherapy is a promising therapeutic approach, but the prognostic value of immune-related genes in osteosarcoma (OS) is unknown. Here, Target-OS RNA-seq data were analyzed to detect differentially expressed genes (DEGs) between OS subgroups, followed by functional enrichment analysis. Cox proportional risk regression was performed for each immune-related gene, and a risk score model to predict the prognosis of patients with OS was constructed. The risk scores were calculated using the risk signature to divide the training set into high-risk and low-risk groups, and validation was performed with GSE21257. We identified two immune-associated clusters, C1 and C2. C1 was closely related to immunity, and the immune score was significantly higher in C1 than in C2. Furthermore, we validated 6 immune cell hub genes related to the prognosis of OS: CD8A, KIR2DL1, CD79A, APBB1IP, GAL, and PLD3. Survival analysis revealed that the prognosis of the high-risk group was significantly worse than that of the low-risk group. We also explored whether the 6-gene prognostic risk model was effective for survival prediction. In conclusion, the constructed a risk score model based on immune-related genes and the survival of patients with OS could be a potential tool for targeted therapy.

Engineering CAR-NK cells to secrete IL-15 sustains their anti-AML functionality but is associated with systemic toxicities

Background

The prognosis of patients with recurrent/refractory acute myelogenous leukemia (AML) remains poor and cell-based immunotherapies hold promise to improve outcomes. Natural Killer (NK) cells can elicit an antileukemic response via a repertoire of activating receptors that bind AML surface ligands. NK-cell adoptive transfer is safe but thus far has shown limited anti-AML efficacy. Here, we aimed to overcome this limitation by engineering NK cells to express chimeric antigen receptors (CARs) to boost their anti-AML activity and interleukin (IL)-15 to enhance their persistence.

Methods

We characterized in detail NK-cell populations expressing a panel of AML (CD123)-specific CARs and/or IL-15 in vitro and in AML xenograft models.

Results

CARs with 2B4.ζ or 4-1BB.ζ signaling domains demonstrated greater cell surface expression and endowed NK cells with improved anti-AML activity in vitro. Initial in vivo testing revealed that only 2B4.ζ Chimeric Antigen Receptor (CAR)-NK cells had improved anti-AML activity in comparison to untransduced (UTD) and 4-1BB.ζ CAR-NK cells. However, the benefit was transient due to limited CAR-NK-cell persistence. Transgenic expression of secretory interleukin (sIL)-15 in 2B4.ζ CAR and UTD NK cells improved their effector function in the setting of chronic antigen simulation in vitro. Multiparameter flow analysis after chronic antigen exposure identified the expansion of unique NK-cell subsets. 2B4.ζ/sIL-15 CAR and sIL-15 NK cells maintained an overall activated NK-cell phenotype. This was confirmed by transcriptomic analysis, which revealed a highly proliferative and activated signature in these NK-cell groups. In vivo, 2B4.ζ/sIL-15 CAR-NK cells had potent anti-AML activity in one model, while 2B4.ζ/sIL-15 CAR and sIL-15 NK cells induced lethal toxicity in a second model.

Conclusion

Transgenic expression of CD123-CARs and sIL-15 enabled NK cells to function in the setting of chronic antigen exposure but was associated with systemic toxicities. Thus, our study provides the impetus to explore inducible and controllable expression systems to provide cytokine signals to AML-specific CAR-NK cells before embarking on early-phase clinical testing.

Tumour-infiltrating bystander CD8+ T cells activated by IL-15 contribute to tumour control in non-small cell lung cancer

BACKGROUND

Tumour-unrelated, virus-specific bystander CD8⁺ T cells were recently shown to be abundant among tumour-infiltrating lymphocytes (TILs). However, their roles in tumour immunity have not been elucidated yet.

METHODS

We studied the characteristics of bystander CD8⁺ TILs from non-small cell lung cancer (NSCLC) tissues (N=66) and their activation by interleukin (IL)-15 to repurpose them for tumour immunotherapy.

RESULTS

We show that bystander CD8⁺ TILs specific to various viruses are present in human NSCLC tissues. We stimulated CD8⁺ TILs ex vivo using IL-15 without cognate antigens and found that IL-15 treatment upregulated NKG2D expression on CD8⁺ TILs, resulting in NKG2D-dependent production of interferon (IFN)-γ (p=0.0006). Finally, we tested whether IL-15 treatment can control tumour growth in a murine NSCLC model with or without a history of murine cytomegalovirus (MCMV) infection. IL-15 treatment reduced the number of tumour nodules in the lung only in mice with MCMV infection (p=0.0037). We confirmed that MCMV-specific bystander CD8⁺ TILs produced interferon (IFN)-γ after IL-15 treatment, and that IL-15 treatment in MCMV-infected mice upregulated tumour necrosis factor-α and IFN-γ responsive genes in tumour microenvironment.

CONCLUSION

Thus, the study demonstrates that bystander CD8⁺ TILs can be repurposed by IL-15 for tumour immunotherapy.

Payload Delivery: Engineering Immune Cells to Disrupt the Tumour Microenvironment

Although chimeric antigen receptor (CAR) T cells have shown impressive clinical success against haematological malignancies such as B cell lymphoma and acute lymphoblastic leukaemia, their efficacy against non-haematological solid malignancies has been largely disappointing. Solid tumours pose many additional challenges for CAR T cells that have severely blunted their potency, including homing to the sites of disease, survival and persistence within the adverse conditions of the tumour microenvironment, and above all, the highly immunosuppressive nature of the tumour milieu. Gene engineering approaches for generating immune cells capable of overcoming these hurdles remain an unmet therapeutic need and ongoing area of research. Recent advances have involved gene constructs for membrane-bound and/or secretable proteins that provide added effector cell function over and above the benefits of classical CAR-mediated cytotoxicity, rendering immune cells not only as direct cytotoxic effectors against tumours, but also as vessels for payload delivery capable of both modulating the tumour microenvironment and orchestrating innate and adaptive anti-tumour immunity. We discuss here the novel concept of engineered immune cells as vessels for payload delivery into the tumour microenvironment, how these cells are better adapted to overcome the challenges faced in a solid tumour, and importantly, the novel gene engineering approaches required to deliver these more complex polycistronic gene constructs.

Phase I study of single agent NIZ985, a recombinant heterodimeric IL-15 agonist, in adult patients with metastatic or unresectable solid tumors

Background

NIZ985 is a recombinant heterodimer of physiologically active interleukin (IL-)15 and IL-15 receptor alpha. In preclinical models, NIZ985 promotes cytotoxic lymphocyte proliferation, killing function, and organ/tumor infiltration, with resultant anticancer effects. In this first-in-human study, we assessed the safety, pharmacokinetics, and immune effects of NIZ985 in patients with metastatic or unresectable solid tumors.

Methods

Single agent NIZ985 dose escalation data are reported from a phase I dose escalation/expansion study of NIZ985 as monotherapy. Adult patients (N=14) received 0.25, 0.5, 1, 2 or 4 µg/kg subcutaneous NIZ985 three times weekly (TIW) for the first 2 weeks of each 28-day cycle, in an accelerated 3+3 dose escalation trial design. IL-15 and endogenous cytokines were monitored by ELISA and multiplexed electrochemiluminescent assays. Multiparameter flow cytometry assessed the frequency, phenotype and proliferation of peripheral blood mononuclear cells. Preliminary antitumor activity was assessed by overall response rate (Response Evaluation Criteria in Solid Tumors V.1.1).

Results

As of March 2, 2020, median treatment duration was 7.5 weeks (range 1.1–77.1). Thirteen patients had discontinued and one (uveal melanoma) remains on treatment with stable disease. Best clinical response was stable disease (3 of 14 patients; 21%). The most frequent adverse events (AEs) were circular erythematous injection site reactions (100%), chills (71%), fatigue (57%), and fever (50%). Treatment-related grade 3/4 AEs occurred in six participants (43%); treatment-related serious AEs (SAEs) in three (21%). The per-protocol maximum tolerated dose was not reached. Pharmacokinetic accumulation of serum IL-15 in the first week was followed by significantly lower levels in week 2, likely due to more rapid cytokine consumption by an expanding lymphocyte pool. NIZ985 treatment was associated with increases in several cytokines, including interferon (IFN)-γ, IL-18, C-X-C motif chemokine ligand 10, and tumor necrosis factor-β, plus significant induction of cytotoxic lymphocyte proliferation (including natural killer and CD8⁺ T cells), increased CD16⁺ monocytes, and increased CD163⁺ macrophages at injection sites.

Conclusions

Subcutaneous NIZ985 TIW was generally well tolerated in patients with advanced cancer and produced immune activation paralleling preclinical observations, with induction of IFN-γ and proliferation of cytotoxic lymphocytes. Due to delayed SAEs at the two highest dose levels, administration is being changed to once-weekly in a revised protocol, as monotherapy and combined with checkpoint inhibitor spartalizumab. These alterations are expected to maximize the potential of NIZ985 as a novel immunotherapy.

Trial registration number

NCT02452268.

IL-15 Trans-Presentation Is an Autonomous, Antigen-Independent Process

IL-15 plays a pivotal role in the long-term survival of T cells and immunological memory. Its receptor consists of three subunits (IL-15Rα, IL-2/15Rβ, and γ_c). IL-15 functions mainly via trans-presentation (TP), during which an APC expressing IL-15 bound to IL-15Rα presents the ligand to the βγ_c receptor-heterodimer on a neighboring T/NK cell. To date, no direct biophysical evidence for the intercellular assembly of the IL-15R heterotrimer exists. Ag presentation (AP), the initial step of T cell activation, is also based on APC-T cell interaction. We were compelled to ask whether AP has any effect on IL-15 TP or whether they are independent processes. In our human Raji B cell-Jurkat T cell model system, we monitored inter-/intracellular protein interactions upon formation of IL-15 TP and AP receptor complexes by Förster resonance energy transfer measurements. We detected enrichment of IL-15Rα and IL-2/15Rβ at the synapse and positive Förster resonance energy transfer efficiency if Raji cells were pretreated with IL-15, giving direct biophysical evidence for IL-15 TP. IL-15Rα and MHC class II interacted and translocated jointly to the immunological synapse when either ligand was present, whereas IL-2/15Rβ and CD3 moved independently of each other. IL-15 TP initiated STAT5 phosphorylation in Jurkat cells, which was not further enhanced by AP. Conversely, IL-15 treatment slightly attenuated Ag-induced phosphorylation of the CD3ζ chain. Our studies prove that in our model system, IL-15 TP and AP can occur independently, and although AP enhances IL-15R assembly, it has no significant effect on IL-15 signaling during TP. Thus, IL-15 TP can be considered an autonomous, Ag-independent process.

Metformin promotes anticancer activity of NK cells in a p38 MAPK dependent manner

Metformin, a drug prescribed to treat type 2 diabetes, has been reported to possess antitumor activity via immunity activation. However, the influence of metformin on natural killer (NK) cells is not fully understood. Here, we investigated whether metformin exerts a potent anticancer effect by activating NK cells. The results showed that sustained exposure to metformin enhances the cytolytic activity of NK-92 cells. Moreover, this enhancement of cytotoxicity by metformin was also observed in NK cells from healthy peripheral blood and cancer patient ascites. Mechanistically, metformin induced activation of the JAK1/2/3/STAT5 and AKT/mTOR pathways in a p38 MAPK-dependent manner rather than an AMPK-dependent manner. In vivo experiments, metformin also improved cancer surveillance of NK cells in mouse models of lymphoma clearance and metastatic melanoma. Additionally, combination treatment with metformin and anti-PD-1 antibodies increased the therapy response rates of B16F10 melanoma. Moreover, metformin treatment increased NK cell and T cell infiltration in tumors. Therefore, these results provide a deeper understanding of metformin on the effector function of NK cells and will contribute to the development and applications of metformin in cancer treatment strategies.

Sepsis-Induced Immunosuppression

Sepsis is expected to have a substantial impact on public health and cost as its prevalence increases. Factors contributing to increased prevalence include a progressively aging population, advances in the use of immunomodulatory agents to treat a rising number of diseases, and immune-suppressing therapies in organ transplant recipients and cancer patients. It is now recognized that sepsis is associated with profound and sustained immunosuppression, which has been implicated as a predisposing factor in the increased susceptibility of patients to secondary infections and mortality. In this review, we discuss mechanisms of sepsis-induced immunosuppression and biomarkers that identify a state of impaired immunity. We also highlight immune-enhancing strategies that have been evaluated in patients with sepsis, as well as therapeutics under current investigation. Finally, we describe future challenges and the need for a new treatment paradigm, integrating predictive enrichment with patient factors that may guide the future selection of tailored immunotherapy. Expected final online publication date for the Annual Review of Physiology, Volume 84 is February 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.