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10 result(s) for "Veluchamy, John P."
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The Rise of Allogeneic Natural Killer Cells As a Platform for Cancer Immunotherapy: Recent Innovations and Future Developments
Natural killer (NK) cells are critical immune effector cells in the fight against cancer. As NK cells in cancer patients are highly dysfunctional and reduced in number, adoptive transfer of large numbers of cytolytic NK cells and their potential to induce relevant antitumor responses are widely explored in cancer immunotherapy. Early studies from autologous NK cells have failed to demonstrate significant clinical benefit. In this review, the clinical benefits of adoptively transferred allogeneic NK cells in a transplant and non-transplant setting are compared and discussed in the context of relevant NK cell platforms that are being developed and optimized by various biotech industries with a special focus on augmenting NK cell functions.
Standardized and flexible eight colour flow cytometry panels harmonized between different laboratories to study human NK cell phenotype and function
Advancements in multi-colour fluorescence activated cell sorting (FACS) panel warrant harmonized procedures to obtain comparable data between various laboratories. The intensifying clinical exploration of Natural Killer (NK) cell-based immunotherapy demands standardized and harmonized NK cell FACS panels and acquisition protocols. Eight colour FACS panels were designed to study human NK cell phenotype and function within peripheral blood mononuclear cells (PBMC). The panels were designed around fixed backbone markers and channels, covering antigens for non-NK lineage exclusion (CD3, TCRγδ, CD19, CD14, SYTOX ® Blue) and NK cell selection (CD45, CD56, CD16), complemented with variable drop-in markers/channels to study NK cell phenotype (NKG2A, NKG2C, NKG2D and KIR2D) or NK cell function and activation (CD25, NKp44 and CD107a). Harmonized FACS set-up and data analysis for three different flow cytometers has been established, leading to highly comparable and reproducible data sets using the same PBMC reference samples (n = 6). Further studies of NK cells in fresh or cryopreserved PBMC samples (n = 12) confirmed that freezing and thawing of PBMC samples did not significantly affect NK phenotype or function. In conclusion, our data demonstrate that cryopreserved PBMC samples analysed by standardized FACS panels and harmonized analysis protocols will generate highly reliable data sets for multi-center clinical trials under validated conditions.
In Vivo Efficacy of Umbilical Cord Blood Stem Cell-Derived NK Cells in the Treatment of Metastatic Colorectal Cancer
Therapeutic monoclonal antibodies against the epidermal growth factor receptor (EGFR) act by inhibiting EGFR downstream signaling and by eliciting a natural killer (NK) cell-mediated antitumor response. The IgG mAb cetuximab has been used for treatment of RAS metastatic colorectal cancer (mCRC) patients, showing limited efficacy. In the present study, we address the potential of adoptive NK cell therapy to overcome these limitations investigating two allogeneic NK cell products, i.e., allogeneic activated peripheral blood NK cells (A-PBNK) and umbilical cord blood stem cell-derived NK cells (UCB-NK). While cetuximab monotherapy was not effective against EGFR RAS , EGFR RAS , and EGFR BRAF cells, A-PBNK were able to initiate lysis of EGFR colon cancer cells irrespective of RAS or BRAF status. Cytotoxic effects of A-PBNK (but not UCB-NK) were further potentiated significantly by coating EGFR colon cancer cells with cetuximab. Of note, a significantly higher cytotoxicity was induced by UCB-NK in EGFR RAS (42 ± 8 versus 67 ± 7%), EGFR RAS (20 ± 2 versus 37 ± 6%), and EGFR BRAF (23 ± 3 versus 43 ± 7%) colon cancer cells compared to A-PBNK and equaled the cytotoxic efficacy of the combination of A-PBNK and cetuximab. The antitumor efficacy of UCB-NK cells against cetuximab-resistant human EGFR RAS colon cancer cells was further confirmed in an preclinical mouse model where UCB-NK showed enhanced antitumor cytotoxicity against colon cancer independent of EGFR and RAS status. As UCB-NK have been proven safe in a recently conducted phase I clinical trial in acute myeloid leukemia, a fast translation into clinical proof of concept for mCRC could be considered.
High-efficiency lysis of cervical cancer by allogeneic NK cells derived from umbilical cord progenitors is independent of HLA status
Down-regulation of HLA in tumor cells, low numbers and dysfunctionality of NK cells are commonly observed in patients with end-stage cervical cancer. Adoptive transfer of high numbers of cytotoxic NK cells might be a promising treatment approach in this setting. Here, we explored the cytotoxic efficacy on ten cervical cancer cell lines of activated allogeneic NK cells from two sources, i.e., peripheral blood (PBNK) with and without cetuximab (CET), a tumor-specific monoclonal antibody directed against EGFR, or derived from umbilical cord blood (UCB-NK). Whereas CET monotherapy was ineffective against the panel of cervical cancer cell lines, irrespective of their EGFR expression levels and despite their RAS wt status, it significantly enhanced the in vitro cytotoxic efficacy of activated PBNK ( P  = 0.002). Equally superior cytotoxicity over activated PBNK alone was achieved by UCB-NK ( P  < 0.001). Both PBNK- and UCB-NK-mediated cytotoxic activity was dependent on the NK-activating receptors natural killer group 2, member D receptor (NKG2D) and DNAX accessory molecule-1 (DNAM-1) ( P  < 0.05) and unrelated to expression levels of the inhibitory receptors HLA-E and/or HLA-G. Most strikingly, whereas the PBNK’s cytotoxic activity was inversely correlated with HLA-ABC levels ( P  = 0.036), PBNK + CET and UCB-NK cytotoxicity were entirely independent of HLA-ABC expression. In conclusion, this study provides a rationale to initiate a clinical trial for cervical cancer with adoptively transferred allogeneic NK cells, employing either UCB-NK or PBNK + CET for EGFR-expressing tumors. Adoptive transfer of UCB-NK might serve as a generally applicable treatment for cervical cancer, enabled by HLA-, histology- and HPV-independent killing mechanisms.
The expanding clinical phenotype of Bosch-Boonstra-Schaaf optic atrophy syndrome: 20 new cases and possible genotype–phenotype correlations
Bosch-Boonstra-Schaaf optic atrophy syndrome (BBSOAS) is an autosomal-dominant disorder characterized by optic atrophy and intellectual disability caused by loss-of-function mutations in NR2F1. We report 20 new individuals with BBSOAS, exploring the spectrum of clinical phenotypes and assessing potential genotype–phenotype correlations. Clinical features of individuals with pathogenic NR2F1 variants were evaluated by review of medical records. The functional relevance of coding nonsynonymous NR2F1 variants was assessed with a luciferase assay measuring the impact on transcriptional activity. The effects of two start codon variants on protein expression were evaluated by western blot analysis. We recruited 20 individuals with novel pathogenic NR2F1 variants (seven missense variants, five translation initiation variants, two frameshifting insertions/deletions, one nonframeshifting insertion/deletion, and five whole-gene deletions). All the missense variants were found to impair transcriptional activity. In addition to visual and cognitive deficits, individuals with BBSOAS manifested hypotonia (75%), seizures (40%), autism spectrum disorder (35%), oromotor dysfunction (60%), thinning of the corpus callosum (53%), and hearing defects (20%). BBSOAS encompasses a broad range of clinical phenotypes. Functional studies help determine the severity of novel NR2F1 variants. Some genotype–phenotype correlations seem to exist, with missense mutations in the DNA-binding domain causing the most severe phenotypes. Genet Med18 11, 1143–1150.
Genome-wide association study for refractive astigmatism reveals genetic co-determination with spherical equivalent refractive error: the CREAM consortium
To identify genetic variants associated with refractive astigmatism in the general population, meta-analyses of genome-wide association studies were performed for: White Europeans aged at least 25 years (20 cohorts, N  = 31,968); Asian subjects aged at least 25 years (7 cohorts, N  = 9,295); White Europeans aged <25 years (4 cohorts, N  = 5,640); and all independent individuals from the above three samples combined with a sample of Chinese subjects aged <25 years ( N  = 45,931). Participants were classified as cases with refractive astigmatism if the average cylinder power in their two eyes was at least 1.00 diopter and as controls otherwise. Genome-wide association analysis was carried out for each cohort separately using logistic regression. Meta-analysis was conducted using a fixed effects model. In the older European group the most strongly associated marker was downstream of the neurexin-1 ( NRXN1 ) gene (rs1401327, P  = 3.92E−8). No other region reached genome-wide significance, and association signals were lower for the younger European group and Asian group. In the meta-analysis of all cohorts, no marker reached genome-wide significance: The most strongly associated regions were, NRXN1 (rs1401327, P  = 2.93E−07), TOX (rs7823467, P  = 3.47E−07) and LINC00340 (rs12212674, P  = 1.49E−06). For 34 markers identified in prior GWAS for spherical equivalent refractive error, the beta coefficients for genotype versus spherical equivalent, and genotype versus refractive astigmatism, were highly correlated ( r  = −0.59, P  = 2.10E−04). This work revealed no consistent or strong genetic signals for refractive astigmatism; however, the TOX gene region previously identified in GWAS for spherical equivalent refractive error was the second most strongly associated region. Analysis of additional markers provided evidence supporting widespread genetic co-susceptibility for spherical and astigmatic refractive errors.
Erratum: Genome-wide meta-analyses of multiancestry cohorts identify multiple new susceptibility loci for refractive error and myopia
Nat. Genet. 45, 314–318 (2013); doi:10.1038/ng.2554; published online 10 February 2013; corrected after print 9 May 2013 In the version of this article initially published, the affiliations of Daniel W.H. Ho were incorrect, and the spelling of Sarayut Janmahasatian in the author list was incorrect. The errors have been corrected in the HTML and PDF versions of this article.