Genetic loss of the transcription factor NFAT2 (NFATc1), known as important player in lymphocyte development, causes an aggressive course of CLL, as it enhances BCR signaling and leads to highly malignant and proliferative disease (Märklin et al. Nat Commun 2017). To investigate whether and how NFAT2 affects treatment resistance in CLL, we generated a CRISPR/Cas9 based NFAT2 knockout (KO) in MEC-1 CLL cells to model aggressive CLL. In immunodeficient NSG-mice, the NFAT2 KO cells showed a ten-fold higher engraftment in the bone marrow after three weeks compared to scrambled (SCR) controls. Cytotoxicity assays revealed a profoundly higher resistance of NFAT2 KO cells to NK cell killing without detectable differences at the level of recognition as revealed by analyses of NK cell activation, degranulation and IFNy release, which excluded resistance to NK cells was due to altered immunogenicity. As CLL patients are routinely treated with anti-CD20 antibody Rituximab, which mediates its therapeutic efficacy in large part by inducing antibody dependent cellular cytotoxicity (ADCC) of NK cells via secretion of perforin and granzymes. When we exposed the target cells to the cytotoxic content isolated out of NK cells, MEC-1 NFAT2 KO cells showed higher resistance for membrane permeabilization compared to SCR controls. In line, perforin blockade equalized susceptibility to membrane permeabilization of both, NFAT2 KO cells and controls, confirming the involvement of NFAT2 in maintaining membrane integrity. In addition, caspase 3/7 activation was reduced in NFAT2 KO cells upon exposure to NK cell granule content as well as upon treatment with staurosporine. This shows an important role of NFAT2 for resistance of the leukemic cells at early stages of apoptosis. The results on the role of NFAT2 in resistance to NK effector function were confirmed with primary CLL patient cells, which were grouped according to high and low NFAT2 expression followed by treatment with NK cell content. Our results demonstrate that loss of NFAT2 allows CLLs cells to evade NK cell effector function. This holds true for both, constitutive cytotoxicity and therapeutically induced ADCC and is due to lowered susceptibility of the leukemic cells to perforin mediated membrane permeabilization and intrinsic resistance to granzyme induced apoptosis. Thus, NFAT2 loss, which correlates with aggressive clinical course in patients, facilitates resistance of CLL cells to CD20 antibody-based treatment. Citation Format: Samuel J. Holzmayer, Sarah M. Greiner, Kuebra Kaban, Jonas S. Heitmann, Helmut R. Salih, Melanie Maerklin. NFAT2 determines susceptibility of chronic lymphocytic leukemia cells to constitutive and Rituximab-induced NK cell killing [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2102.
T-cell immunity is central for the control of COVID-19, in particular in patients incapable to mount a humoral immune response. We previously reported on the favorable safety profile and efficacy in terms of induction of SARS-CoV-2-specific T-cell responses by CoVac-1, a peptide-based T-cell activator, composed of SARS-CoV-2 T-cell epitopes derived from various viral proteins, combined with the toll-like receptor 1/2 agonist XS151. We conducted a Phase I/II open-label trial recruiting 54 patients with congenital or acquired B-cell deficiency who received one single subcutaneous dose of CoVac-1. Immunogenicity until day 28 in terms of CoVac-1-induced T-cell responses was the primary endpoint; safety until day 56 was assessed as secondary endpoint. Neither serious nor grade 4 CoVac-1-related adverse events were observed. The expected local granuloma formation was observed in 94% of study subjects, whereas systemic reactogenicity was mostly mild or absent. SARS-CoV-2-specific Tcell responses were induced in 86% of the patients and directed to multiple CoVac-1 peptides, not affected by any current Omicron variants and mediated by multifunctional T-helper 1 CD4+ T cells. CoVac-1-induced T-cell responses exceeded spike-specific T-cell responses after vaccination with mRNA vaccines in B-cell deficient patients and also that of immunocompetent COVID-19 convalescents with and without seroconversion. CoVac-1 induces broad and potent T-cell responses in patients with Bcell/antibody deficiency independently of current variants of concern, with a favorable safety profile. Our data warrant advancement to a pivotal Phase II/III safety and efficacy evaluation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.