CTCF variants in 39 individuals with a variable neurodevelopmental disorder broaden the mutational and clinical spectrum

Purpose: Pathogenic variants in the chromatin organizer CTCF were previously reported in seven individuals with a neurodevelopmental disorder (NDD). Methods: Through international collaboration we collected data from 39 subjects with variants in CTCF. We performed transcriptome analysis on RNA from blood samples and utilized Drosophila melanogaster to investigate the impact of Ctcf dosage alteration on nervous system development and function. Results: The individuals in our cohort carried 2 deletions, 8 likely gene-disruptive, 2 splice-site, and 20 different missense variants, most of them de novo. Two cases were familial. The associated phenotype was of variable severity extending from mild developmental delay or normal IQ to severe intellectual disability. Feeding difficulties and behavioral abnormalities were common, and variable other findings including growth restriction and cardiac defects were observed. RNA-sequencing in five individuals identified 3828 deregulated genes enriched for known NDD genes and biological processes such as transcriptional regulation. Ctcf dosage alteration in Drosophila resulted in impaired gross neurological functioning and learning and memory deficits. Conclusion: We significantly broaden the mutational and clinical spectrum of CTCF-associated NDDs. Our data shed light onto the functional role of CTCF by identifying deregulated genes and show that Ctcf alterations result in nervous system defects in Drosophila.Peer reviewe

Evidence of T cell activation and intratumoral nivolumab-presence in glioblastoma patients treated with nivolumab and bevacizumab

Glioblastoma (GBM) is an aggressive brain tumor with a dismal prognosis. Salvage neurosurgical resection is performed if possible and GBM patients are hereafter treated with Stupp’s regime as standard treatment in the primary setting. However, after relapse, treatment in the recurrent setting shows very limited effect. We are monitoring the immune system of patients participating in a phase II clinical trial, where patients with recurrent GBM receive Nivolumab and Bevacizumab, treatments blocking PD1 and VEGF, respectively. The clinical trial consists of two arms. Arm A includes patients where surgical removal of the tumor is possible, and arm B includes patients who are only able to receive medical treatment. Arm A has received Nivolumab 7 days prior to surgery. Single cells suspension was produced from the resected tumors and blood samples was collected from patients through the course of treatment, wherefrom PBMCs (peripheral blood mononuclear cells) were purified. All samples were immunophenotyped using multi-color flow cytometry, to identify and follow the distribution of various immune cell types, and determine their expression of activating and inhibitory molecules over the course of treatment, in the periphery and in the tumor. An activated subset of T cells was characterized by CD103 (tissue residence), CD39 (antigen exposure) and CD69 (cytotoxicity). Such T cell populations were significantly enriched in the tumor. Importantly, we could demonstrate the presence of Nivolumab in the tumor, using an anti-IgG4 antibody to detect Nivolumab binding to T cells. We observed IgG4 positive T cell in the tumor digest, suggesting T cells binding Nivolumab are present in the tumor. Additional data analysis will be performed prior to the conference. With this we hope to gain further knowledge of the immune system’s role in tumor clearance in the brain and the impact of immunotherapy hereupon

Nivolumab and bevacizumab for recurrent glioblastoma; t-cell reactivity against autologous tumor cells

INTRODUCTION: Glioblastoma is an aggressive brain tumor with a median survival of 14.6 months. We have no standard treatment for relapse and known options have limited effect. Novel treatments are necessary to improve survival and quality of life. METHODS: We present our trial; phase II open label, two-armed translational study of Nivolumab and Bevacizumab for recurrent GBM, who have failed Stupp’s regimen. Patients are included in two arms depending on the possibility of salvage neurosurgical resection. Both arms receive Nivolumab and Bevacizumab administrated every second weekend, and the surgical arm also receive Nivolumab 7 days prior surgery. Forty-four patients were included by January 2021; 20 in each arm (four screen-failures). In the surgical arm, 20 fresh tumor samples as well as paired tissue from primary tumor were available. Tumor infiltrating lymphocytes (TILs) and tumor digest were produced in vitro from recurrent settings. Young TILs were expanded from fresh tumor fragments after minimal-culture, whereas rapidly expanded TILs (REP TILs) were obtained after massive expansion. By intracellular cytokine staining, we investigated the TIL reactivity after exposure to autologous tumor digest in order to evaluate whether the TILs were tumor-reactive, non-reactive or bystanders. RNA and whole exome sequencing were available before and after treatment. RESULTS: Material from 19 patients was analyzed (one out of the 20 collected biopsies was limited in size, therefore no tumor digest could be produced). Four out of 19 TIL samples showed tumor reactivity after exposure to the autologous tumor digest. Tumor reactivity was ranged between 1,2 to 13,6 tox% in CD8+ TILs and between 2,8 to 10,9 tox% in CD4+ TILs. By flowcytometry we found, IgG4+ CD3+ TILS from tumor biopsies, meaning that Nivolumab were found in the brain. Currently controls are included to evaluate these results. CONCLUSIONS: Updated results will be presented at SNO