Natural killer cell therapies

Natural killer (NK) cells are lymphocytes of the innate immune system. A key feature of NK cells is their ability to recognize a wide range of cells in distress, particularly tumour cells and cells infected with viruses. They combine both direct effector functions against their cellular targets and participate in the generation, shaping and maintenance of a multicellular immune response. As our understanding has deepened, several therapeutic strategies focused on NK cells have been conceived and are currently in various stages of development, from preclinical investigations to clinical trials. Here we explore in detail the complexity of NK cell biology in humans and highlight the role of these cells in cancer immunity. We also analyse the harnessing of NK cell immunity through immune checkpoint inhibitors, NK cell engagers, and infusions of preactivated or genetically modified, autologous or allogeneic NK cell products.

10th antibody industrial symposium: new developments in antibody and adoptive cell therapies

The annual "Antibody Industrial Symposium", co-organized by LabEx MAbImprove and MabDesign, held its 10th anniversary edition in Montpellier, France, on June 28-29, 2022. The meeting focused on new results and concepts in antibody engineering (naked, mono- or multi-specific, conjugated to drugs or radioelements) and also on new cell-based therapies, such as chimeric antigenic receptor (CAR)-T cells. The symposium, which brought together scientists from academia and industry, also addressed issues concerning the production of these molecules and cells, and the necessary steps to ensure a strong intellectual property protection of these new molecules and approaches. These two days of exchanges allowed a rich discussion among the various actors in the field of therapeutic antibodies.

Antitumor immunity induced by antibody-based natural killer cell engager therapeutics armed with not-alpha IL-2 variant

Harnessing innate immunity is emerging as a promising therapeutic approach in cancer. We report here the design of tetraspecific molecules engaging natural killer (NK) cell-activating receptors NKp46 and CD16a, the β-chain of the interleukin-2 receptor (IL-2R), and a tumor-associated antigen (TAA). In vitro, these tetraspecific antibody-based natural killer cell engager therapeutics (ANKETs) induce a preferential activation and proliferation of NK cells, and the binding to the targeted TAA triggers NK cell cytotoxicity and cytokine and chemokine production. In vivo, tetraspecific ANKETs induce NK cell proliferation and their accumulation at the tumor bed, as well as the control of local and disseminated tumors. Treatment of non-human primates with CD20-directed tetraspecific ANKET leads to CD20⁺ circulating B cell depletion, with minimal systemic cytokine release and no sign of toxicity. Tetraspecific ANKETs, thus, constitute a technological platform for harnessing NK cells as next-generation cancer immunotherapies.

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Tetraspecific ANKETs constitute a technological platform to harness NK cells in cancer

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Tetraspecific ANKETs target NKp46, CD16a, IL-2Rβ, and a tumor antigen

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Tetraspecific ANKETs stimulate NK cell proliferation, activation, and antitumor functions

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In vivo, tetraspecific ANKETs promote NK cell tumor accumulation and antitumor activity

851 Harnessing innate immunity in cancer therapies: the example of natural killer cell engagers

Background

Most immunomodulatory approaches have focused on enhancing T-cell responses, with immune checkpoint inhibitors, chimeric antigen receptor T cells or bispecific antibodies. Although these therapies have led to exceptional successes, only a minority of cancer patients benefit from these treatments, highlighting the need to identify new cells and molecules that could be exploited in the next generation of immunotherapy. Given the crucial role of innate immune responses in immunity, harnessing these responses opens up new possibilities for tumor control. Antibody engineering provides us with great opportunities to induce synthetic immunity and to optimize the biological functions of innate immune cells, in particular by boosting the capacity of Natural Killer (NK) cells to kill tumor cells directly and to stimulate T-cell responses indirectly.

Methods

In order to leverage the advantages of harnessing NK cell effector functions, we used our Antibody-based NK cell Engager Therapeutics (ANKET) molecular platform1 and designed a new generation of molecules that can engage activating receptors NKp46 and CD16, the IL-2Rβ chain and a tumor antigen in a single tetra-specific molecule (ANKET4). The variant of interleukin-2 (IL-2v) integrated in the ANKET4 molecule is unable to bind the α-subunit of its receptor to limit regulatory T cell activation and IL-2Rα-mediated toxicity.

Results

In vitro, ANKET4 provides proliferation and activation signals targeted to NK cells and induces primary human NK cell cytolytic activity and the secretion of cytokines and chemokines only after binding to the tumor target. In mouse models of both invasive and solid tumors, ANKET4 induced NK cell proliferation and accumulation at the tumor bed, and had a higher anti-tumor efficacy than approved therapeutic antibodies targeting the same tumor antigen. Mechanistically, transcriptomic analysis and in-vivo studies revealed that the geometry of the ANKET4 molecule including NKp46, CD16 and IL-2 receptor binding moieties on the same molecule was essential for its strong activity which results from a synthetic cooperativity between immunoreceptor tyrosine-based activation motif (ITAM) and cytokine signaling pathways. In non-human primates, CD20-directed ANKET4 resulted in sustained CD20+ B-cell depletion with minimal systemic cytokine release and no clinical sign of toxicity.

Conclusions

Tetra-specific ANKET4 thus constitutes a technological platform combining the induction of NK cell proliferation and effector functions with a manageable safety profile, supporting its clinical development for next-generation cancer immunotherapies.

Reference

Gauthier L, Morel A, Anceriz N, Rossi B, Blanchard-Alvarez A, Grondin G, et al. Multifunctional natural killer cell engagers targeting NKp46 trigger protective tumor immunity. Cell 2019;177(7):1701–13 e16.

Ethics Approval

Primary immune cells were purified from buffy coats from healthy donors obtained from Etablissement Francais du Sang (EFS, Marseille) with written consent from each volunteer.All mouse experiments were performed in accordance with the rules of the Innate Pharma ethics committee and were approved by the Ministère de l’Enseignement Supérieur, de la Recherche et de l’Innovation – France (APAFIS# 19272 ).All non human-primate procedures were conducted according to European guidelines for animal care and use for scientific purposes (Directive 63-2010, ”Journal Officiel des Communautés Européennes”, L276, September 22, 2010) and according to CEA institutional guidelines. The study was approved by the local ethical committee under the number A18_080 and by the French Administration (APAFIS#20525-2019050616506478 v1)

Targeting MICA/B with cytotoxic therapeutic antibodies leads to tumor control

Background: MICA and MICB are tightly regulated stress-induced proteins that trigger the immune system by binding to the activating receptor NKG2D on cytotoxic lymphocytes. MICA and MICB are highly polymorphic molecules with prevalent expression on several types of solid tumors and limited expression in normal/healthy tissues, making them attractive targets for therapeutic intervention. Methods: We have generated a series of anti-MICA and MICB cross-reactive antibodies with the unique feature of binding to the most prevalent isoforms of both these molecules. Results: The anti-MICA and MICB antibody MICAB1, a human IgG1 Fc-engineered monoclonal antibody (mAb), displayed potent antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP) of MICA/B-expressing tumor cells in vitro. However, it showed insufficient efficiency against solid tumors in vivo, which prompted the development of antibody-drug conjugates (ADC). Indeed, optimal tumor control was achieved with MICAB1-ADC format in several solid tumor models, including patient-derived xenografts (PDX) and carcinogen-induced tumors in immunocompetent MICAgen transgenic mice. Conclusions: These data indicate that MICA and MICB are promising targets for cytotoxic immunotherapy.

Targeting MICA/B with cytotoxic therapeutic antibodies leads to tumor control

Background: MICA and MICB are tightly regulated stress-induced proteins that trigger the immune system by binding to the activating receptor NKG2D on cytotoxic lymphocytes. MICA and MICB are highly polymorphic molecules with prevalent expression on several types of solid tumors and limited expression in normal/healthy tissues, making them attractive targets for therapeutic intervention. Methods: We have generated a series of anti-MICA and MICB cross-reactive antibodies with the unique feature of binding to the most prevalent isoforms of both these molecules. Results: The anti-MICA and MICB antibody MICAB1, a human IgG1 Fc-engineered monoclonal antibody (mAb), displayed potent antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP) of MICA/B-expressing tumor cells in vitro. However, it showed insufficient efficiency against solid tumors in vivo, which prompted the development of antibody-drug conjugates (ADC). Indeed, optimal tumor control was achieved with MICAB1-ADC format in several solid tumor models, including patient-derived xenografts (PDX) and carcinogen-induced tumors in immunocompetent MICAgen transgenic mice. Conclusions: These data indicate that MICA and MICB are promising targets for cytotoxic immunotherapy.

[Natural killer cells: promising targets in cancer therapy]

L’immuno-oncologie est une approche d’immunothérapie novatrice qui change le traitement des cancers en stimulant la capacité du système immunitaire à reconnaître et éliminer les cellules tumorales. Cette approche a pour but de mettre en place une immuno-surveillance anti-tumorale durable chez des patients pour lesquels les thérapies conventionnelles ont échoué.

Abstract 5037: Targeting MICA with therapeutic antibodies for the treatment of cancer

MICA and MICB, along with ULPBs, are ligands for the activating receptor NKG2D expressed on NK cells and subsets of T cells in Human. NKG2D ligands are induced by cellular stress and pathogen infections. Their expression is tightly regulated by complex mechanisms both at the mRNA and protein levels. In the case of MICA and MICB, more than 65 and 30 alleles respectively were described with different properties regarding to their cellular location adding to the complexity of this recognition system. Nevertheless, as markers of cellular stress, in particular in tumorigenesis, MICA and the closely related MICB proteins are candidates of choice to be targeted by a cytotoxic therapeutic antibody. We first evaluated MICA/B expression by immunohistochemistry on healthy tissues and tumors to validate these antigens as therapeutic targets. Then, using mouse immunization, we generated a panel of chimeric human IgG1 monoclonal antibodies targeting MICA and MICB. These mAbs have the ability to bind to several structurally different alleles and to cross-react on MIC proteins from cynomolgus macaques. Their capacity to block the MICA/NKG2D interaction was assessed by surface plasmon resonance as well as by using cell-based assays. In vitro efficacy was measured by the capacity to mediate complement-dependent cytotoxicity (CDC) and antibody-dependent cell cytotoxicity (ADCC) towards MICA expressing cells. In vivo efficacy of the anti-MICA mAbs was measured in both a preventive and a curative setting using MICA expressing cell lines. Altogether, we have generated a panel of anti-MICA mAbs with diverse functional properties. Ongoing work aims to choose the best candidate for humanization and further clinical development.

Citation Format: Mathieu Blery, Cécile Bonnafous, Valentine Peri, Sylvia Trichard, Ivan Perrot, Stéphanie Cornen, Ariane Thielens, Violette Breso, Yannis Morel, François Romagne, Benjamin Rossi, Carine Paturel, Laurent Gauthier. Targeting MICA with therapeutic antibodies for the treatment of cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5037. doi:10.1158/1538-7445.AM2014-5037