Phase I study protocol: NKTR-255 as monotherapy or combined with daratumumab or rituximab in hematologic malignancies

Circumventing resistance within the Ewing sarcoma microenvironment by combinatorial innate immunotherapy

BACKGROUND

Pediatric patients with recurrent/metastatic Ewing sarcoma (ES) have a dismal 5-year survival. Novel therapeutic approaches are desperately needed. Natural killer (NK) cell number and function are low in ES patient tumors, in large part due to the immunosuppressive tumor microenvironment (TME). Melanoma cell adhesion molecule (MCAM) is highly expressed on ES and associated with ES metastasis. NKTR-255 is a polymer-conjugated recombinant human interleukin-15 (IL-15) agonist improving NK cell activity and persistence. Magrolimab (MAG) is a CD47 blockade that reactivates the phagocytic activity of macrophages.

METHODS

Transcriptome profiling coupled with CIBERSORT analyses in both ES mouse xenografts and human patient tumors were performed to identify mechanisms of NK resistance in ES TME. A chimeric antigen receptor (CAR) NK cell targeting MCAM was engineered by CAR mRNA electroporation into ex vivo expanded NK cells. In vitro cytotoxicity assays were performed to investigate the efficacy of anti-MCAM-CAR-NK cell alone or combined with NKTR-255 against ES cells. Interferon-γ and perforin levels were measured by ELISA. The effect of MAG on macrophage phagocytosis of ES cells was evaluated by in vitro phagocytosis assays. Cell-based and patient-derived xenograft (PDX)-based xenograft mouse models of ES were used to investigate the antitumor efficacy of CAR-NK alone and combined with NKTR-255 and MAG in vivo.

RESULTS

We found that NK cell infiltration and activity were negatively regulated by tumor-associated macrophages (TAM) in ES TME. Expression of anti-MCAM CAR significantly and specifically enhanced NK cytotoxic activity against MCAMhigh but not MCAM-knockout ES cells in vitro, and significantly reduced lung metastasis and extended animal survival in vivo. NKTR-255 and MAG significantly enhanced in vitro CAR-NK cytotoxicity and macrophage phagocytic activity against ES cells, respectively. By combining with NKTR-255 and MAG, the anti-MCAM-CAR-NK cell significantly decreased primary tumor growth and prolonged animal survival in both cell- and PDX-based ES xenograft mouse models.

CONCLUSIONS

Our preclinical studies demonstrate that immunotherapy via the innate immune system by combining tumor-targeting CAR-NK cells with an IL-15 agonist and a CD47 blockade is a promising novel therapeutic approach to targeting MCAMhigh malignant metastatic ES.

Efficient combination of radiotherapy and CAR-T - A systematic review

Chimeric antigen receptor T (CAR-T) cell therapy, a groundbreaking immunotherapy. However, it faces formidable challenges in treating solid tumors, grappling with issues like poor trafficking, limited penetration, and insufficient persistence within the tumor microenvironment (TME). CAR-T cells are engineered to express receptors that target specific cancer antigens, enhancing their ability to recognize and eliminate cancer cells. This review paper explores the intricate interplay between CAR-T therapy and radiotherapy (RT), investigating their synergistic potential. Radiotherapy, a standard cancer treatment, involves using high doses of radiation to target and damage cancer cells, disrupting their ability to grow and divide. We highlight that RT modulates the TME, augments antigen presentation, and promotes immune cell infiltration, bolstering CAR-T cell-mediated tumor eradication. Molecular insights shed light on RT-induced alterations in tumor stroma, T cell recruitment promotion, and induction of immunogenic cell death. Noteworthy, strategies, such as combining hypofractionated radiotherapy with myeloid-derived suppressor cell blockade, underscore innovative approaches to enhance CAR-T cell therapy in solid tumors. Bridging indications for RT and CAR-T cells in hematological malignancies are discussed, emphasizing scenarios where RT strategically enhances CAR-T cell efficacy. The paper critically evaluates the RT as a bridge compared to traditional chemotherapy, highlighting timing and dosage considerations crucial for optimizing CAR-T therapy outcomes. In summary, the paper provides valuable insights into the intricate molecular mechanisms activated by RT and innovative strategies to improve CAR-T cell therapy, fostering a deeper understanding of their combined potential in cancer treatment.

Engineering cytokines for cancer immunotherapy: a systematic review

Cytokines are pivotal mediators of cell communication in the tumor microenvironment. Multiple cytokines are involved in the host antitumor response, but the production and function of these cytokines are usually dysregulated during malignant tumor progression. Considering their clinical potential and the early successful use of cytokines in cancer immunotherapy, such as interferon alpha-2b (IFNα-2b; IntronA^®) and IL-2 (Proleukin^®), cytokine-based therapeutics have been extensively evaluated in many follow-up clinical trials. Following these initial breakthroughs, however, clinical translation of these natural messenger molecules has been greatly limited owing to their high-degree pleiotropic features and complex biological properties in many cell types. These characteristics, coupled with poor pharmacokinetics (a short half-life), have hampered the delivery of cytokines via systemic administration, particularly because of severe dose-limiting toxicities. New engineering approaches have been developed to widen the therapeutic window, prolong pharmacokinetic effects, enhance tumor targeting and reduce adverse effects, thereby improving therapeutic efficacy. In this review, we focus on the recent progress and competitive landscape in cytokine engineering strategies and preclinical/clinical therapeutics for cancer. In addition, aiming to promote engineered cytokine-based cancer immunotherapy, we present a profound discussion about the feasibility of recently developed methods in clinical medicine translation.

Research progress of interleukin-15 in cancer immunotherapy

Interleukin-15 (IL-15) is a cytokine that belongs to the interleukin-2 (IL-2) family and is essential for the development, proliferation, and activation of immune cells, including natural killer (NK) cells, T cells and B cells. Recent studies have revealed that interleukin-15 also plays a critical role in cancer immunotherapy. Interleukin-15 agonist molecules have shown that interleukin-15 agonists are effective in inhibiting tumor growth and preventing metastasis, and some are undergoing clinical trials. In this review, we will summarize the recent progress in interleukin-15 research over the past 5 years, highlighting its potential applications in cancer immunotherapy and the progress of interleukin-15 agonist development.

Improving NK cell function in multiple myeloma with NKTR-255, a novel polymer-conjugated human IL-15

Multiple myeloma (MM) is characterized by an immunosuppressive microenvironment that enables tumor development. One of the mechanisms of immune evasion used by MM cells is the inhibition of natural killer (NK) cell effector functions; thus, the restoration of NK cell antitumor activity represents a key goal to increase tumor cell recognition, avoid tumor escape and potentially enhancing the effect of other drugs. In this study, we evaluated the ability of the investigational medicine NKTR-255, an IL-15 receptor agonist, to engage the IL-15 pathway and stimulate NK cells against MM cells. We observed that incubation with NKTR-255 was able to tilt the balance toward an activated phenotype in NK cells isolated from peripheral blood mononuclear cells of patients with MM, with increased expression of activating receptors on the surface of treated NK cells. This resulted in an enhanced degranulation, cytokine release, and anti-tumor cytotoxicity when the NK cells were exposed to both MM cell lines and primary MM cells. We further evaluated the in vivo effect of NKTR-255 in fully humanized immunocompetent mice subcutaneously engrafted with H929 MM cells. Compared with placebo, weekly injection of the mice with NKTR-255 increased the number of circulating NK cells in peripheral blood and delayed tumor growth. Finally, we observed that combination of NKTR-255 with the anti-CD38 antibody, daratumumab, was effective against MM cells in vitro and in vivo. Taken together, our data suggest a significant impact of NKTR-255 in inducing NK cell function against MM cells with important translational implications.

The role of interleukin-15 in the development and treatment of hematological malignancies

Cytokines are a vital component of the immune system that controls the activation and growth of blood cells. However, chronic overexpression of cytokines can trigger cellular events leading to malignant transformation. The cytokine interleukin-15 (IL-15) is of particular interest, which has been shown to contribute to the development and progression of various hematological malignancies. This review will provide an overview of the impact of the immunopathogenic function of IL-15 by studying its role in cell survival, proliferation, inflammation, and treatment resistance. We will also review therapeutic approaches for inhibiting IL-15 in blood cancers.

The application of Interleukin-2 family cytokines in tumor immunotherapy research

The Interleukin-2 Family contains six kinds of cytokines, namely IL-2, IL-15, IL-4, IL-7, IL-9, and IL-21, all of which share a common γ chain. Many cytokines of the IL-2 family have been reported to be a driving force in immune cells activation. Therefore, researchers have tried various methods to study the anti-tumor effect of cytokines for a long time. However, due to the short half-life, poor stability, easy to lead to inflammatory storms and narrow safety treatment window of cytokines, this field has been tepid. In recent years, with the rapid development of protein engineering technology, some engineered cytokines have a significant effect in tumor immunotherapy, showing an irresistible trend of development. In this review, we will discuss the current researches of the IL-2 family and mainly focus on the application and achievements of engineered cytokines in tumor immunotherapy.

Overcoming tumor resistance mechanisms in CAR-NK cell therapy

Despite the impressive results of autologous CAR-T cell therapy in refractory B lymphoproliferative diseases, CAR-NK immunotherapy emerges as a safer, faster, and cost-effective approach with no signs of severe toxicities as described for CAR-T cells. Permanently scrutinized for its efficacy, recent promising data in CAR-NK clinical trials point out the achievement of deep, high-quality responses, thus confirming its potential clinical use. Although CAR-NK cell therapy is not significantly affected by the loss or downregulation of its CAR tumor target, as in the case of CAR-T cell, a plethora of common additional tumor intrinsic or extrinsic mechanisms that could also disable NK cell function have been described. Therefore, considering lessons learned from CAR-T cell therapy, the emergence of CAR-NK cell therapy resistance can also be envisioned. In this review we highlight the processes that could be involved in its development, focusing on cytokine addiction and potential fratricide during manufacturing, poor tumor trafficking, exhaustion within the tumor microenvironment (TME), and NK cell short in vivo persistence on account of the limited expansion, replicative senescence, and rejection by patient’s immune system after lymphodepletion recovery. Finally, we outline new actively explored alternatives to overcome these resistance mechanisms, with a special emphasis on CRISPR/Cas9 mediated genetic engineering approaches, a promising platform to optimize CAR-NK cell function to eradicate refractory cancers.

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.

A NK Cell Odyssey: From Bench to Therapeutics Against Hematological Malignancies

In 1975 two independent groups noticed the presence of immune cells with a unique ability to recognize and eliminate transformed hematopoietic cells without any prior sensitization or expansion of specific clones. Since then, NK cells have been the axis of thousands of studies that have resulted until June 2021, in more than 70 000 publications indexed in PubMed. As result of this work, which include approaches in vitro, in vivo, and in natura, it has been possible to appreciate the role played by the NK cells, not only as effectors against specific pathogens, but also as regulators of the immune response. Recent advances have revealed previous unidentified attributes of NK cells including the ability to adapt to new conditions under the context of chronic infections, or their ability to develop some memory-like characteristics. In this review, we will discuss significant findings that have rule our understanding of the NK cell biology, the developing of these findings into new concepts in immunology, and how these conceptual platforms are being used in the design of strategies for cancer immunotherapy.

Novel Cell and Immune Engagers in Optimizing Tumor- Specific Immunity Post-Autologous Transplantation in Multiple Myeloma

Autologous stem cell transplantation (ASCT) is an important component of treatment of multiple myeloma (MM). The post-ASCT setting offers a unique opportunity to increase myeloma specific immunity through enhancement of T and NK cell responses. The vast array of therapeutics being developed for MM, including cell-based therapies, dendritic vaccines, bispecific antibodies, and IL-15 agonists, provide the opportunity to increase tumor-specific immunity. Maintenance therapies, including immunomodulatory drugs, proteasome inhibitors, and daratumumab, exhibit a significant anti-myeloma response by modulating the immune system. Lenalidomide promotes an antitumoral immune microenvironment, whereas daratumumab can potentially cause NK cell fratricide. Thus, understanding the effects of commonly used maintenance drugs on the immune system is important. In this review, we look at current and emerging therapeutics and their integration post-ASCT in the context of immune reconstitution to improve clinical responses in patients with MM. © 2021 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.