Safety and efficacy of secukinumab in patients with giant cell arteritis (TitAIN): a randomised, double-blind, placebo-controlled, phase 2 trial.

BACKGROUND: The treatment of giant cell arteritis with glucocorticoid-sparing agents is an unmet medical need. We evaluated the efficacy and safety of secukinumab, an anti-interleukin-17A monoclonal antibody, in patients with giant cell arteritis. METHODS: We conducted a Bayesian randomised, parallel-group, double-blind, placebo-controlled, multicentre, phase 2 study at 11 clinics or hospitals in Germany. Patients aged 50 years or older with new-onset or relapsing giant cell arteritis who were naive to biological therapy and already receiving glucocorticoids with a prednisolone equivalent dose of 25-60 mg/day were eligible for inclusion. Participants were assigned (1:1) to receive 300 mg secukinumab or placebo subcutaneously once a week up to week 4 and every 4 weeks thereafter. In both treatment groups, prednisolone dose was tapered down to 0 mg over a 26-week period. Patients, investigator staff, and clinical trial team were masked to the treatment assignment. The primary endpoint was the median proportion (Bayesian analysis) of patients with sustained remission until week 28 in the full analysis set (ie, all patients who received at least one dose of assigned treatment, analysed according to treatment assigned at randomisation). Sustained remission rate of the placebo group from a previous trial of tocilizumab in patients with giant cell arteritis was used to derive the prior distribution of placebo sustained remission rate for the primary endpoint. The safety of secukinumab was assessed in the safety set (ie, all patients who received at least one dose of study treatment, analysed according to study treatment received). This trial is completed and is registered with ClinicalTrials.gov, NCT03765788. FINDINGS: Of the 65 patients who were assessed for eligibility, 52 patients (median age 75 years [IQR 69-79]; 35 [67%] female and 17 [33%] male, 52 [100%] White) were enrolled between Jan 30, 2019 and March 30, 2020 and were randomly assigned to receive secukinumab (n=27) or placebo (n=25). Four of 27 patients in the secukinumab group and eight of 25 patients in the placebo group discontinued treatment by week 28 of the study. On the basis of the Bayesian analysis, the median proportion of patients in sustained remission until week 28 was 70% (95% credibility interval 52-85) in the secukinumab group versus 20% (12-30) in the placebo group. The incidence of adverse events was similar in the secukinumab (27 [100%] of 27 patients had any adverse event) and placebo groups (24 [96%] of 25 patients had any adverse event); the most common adverse events were hypertension (six [22%] of 27 patients in the secukinumab group and eight [32%] of 25 patients in the placebo group) and nasopharyngitis (five [19%] of 27 patients in the secukinumab group and five [20%] of 25 patients in the placebo group). Two patients (one in each group) died during the study, neither of which was considered to be related to study treatment. INTERPRETATION: Patients with active giant cell arteritis had a higher sustained remission rate in the secukinumab group than in the placebo group at week 28, in combination with glucocorticoid taper regimen. Secukinumab was tolerated well with no new safety concerns. This proof-of-concept phase 2 study further supports the development of secukinumab as a treatment option for people with giant cell arteritis. FUNDING: Novartis Pharma.

Transcriptional and Translational Differences of Microglia from Male and Female Brains.

Sex differences in brain structure and function are of substantial scientific interest because of sex-related susceptibility to psychiatric and neurological disorders. Neuroinflammation is a common denominator of many of these diseases, and thus microglia, as the brain's immunocompetent cells, have come into focus in sex-specific studies. Here, we show differences in the structure, function, and transcriptomic and proteomic profiles in microglia freshly isolated from male and female mouse brains. We show that male microglia are more frequent in specific brain areas, have a higher antigen-presenting capacity, and appear to have a higher potential to respond to stimuli such as ATP, reflected in higher baseline outward and inward currents and higher protein expression of purinergic receptors. Altogether, we provide a comprehensive resource to generate and validate hypotheses regarding brain sex differences.

Athymic mice reveal a requirement for T-cell-microglia interactions in establishing a microenvironment supportive of Nf1 low-grade glioma growth.

Pediatric low-grade gliomas (LGGs) frequently do not engraft in immunocompromised mice, limiting their use as an experimental platform. In contrast, murine Neurofibromatosis-1 (Nf1) optic LGG stem cells (o-GSCs) form glioma-like lesions in wild-type, but not athymic, mice following transplantation. Here, we show that the inability of athymic mice to support o-GSC engraftment results from impaired microglia/macrophage function, including reduced expression of Ccr2 and Ccl5, both of which are required for o-GSC engraftment and Nf1 optic glioma growth. Impaired Ccr2 and Ccl5 expression in athymic microglia/macrophages was restored by T-cell exposure, establishing T-cell-microglia/macrophage interactions as critical stromal determinants that support NF1 LGG growth.

Cellular heterogeneity contributes to subtype-specific expression of ZEB1 in human glioblastoma.

The transcription factor ZEB1 has gained attention in tumor biology of epithelial cancers because of its function in epithelial-mesenchymal transition, DNA repair, stem cell biology and tumor-induced immunosuppression, but its role in gliomas with respect to invasion and prognostic value is controversial. We characterized ZEB1 expression at single cell level in 266 primary brain tumors and present a comprehensive dataset of high grade gliomas with Ki67, p53, IDH1, and EGFR immunohistochemistry, as well as EGFR FISH. ZEB1 protein expression in glioma stem cell lines was compared to their parental tumors with respect to gene expression subtypes based on RNA-seq transcriptomic profiles. ZEB1 is widely expressed in glial tumors, but in a highly variable fraction of cells. In glioblastoma, ZEB1 labeling index is higher in tumors with EGFR amplification or IDH1 mutation. Co-labeling studies showed that tumor cells and reactive astroglia, but not immune cells contribute to the ZEB1 positive population. In contrast, glioma cell lines constitutively express ZEB1 irrespective of gene expression subtype. In conclusion, our data indicate that immune infiltration likely contributes to differential labelling of ZEB1 and confounds interpretation of bulk ZEB1 expression data.

Changes in phagocytosis and potassium channel activity in microglia of 5xFAD mice indicate alterations in purinergic signaling in a mouse model of Alzheimer's disease.

As the immunocompetent cells of the central nervous system, microglia accumulate at amyloid beta plaques in Alzheimer's disease (AD) and acquire a morphological phenotype of activated microglia. Recent functional studies, however, indicate that in mouse models of amyloidosis and AD, these cells are rather dysfunctional indicated by a reduced phagocytic activity. Here, we report that this reduction in phagocytic activity is associated with perturbed purinergic receptor signaling, since phagocytosis could be stimulated by P2Y6 receptor activation in control, but not in 5xFAD transgenic animals, an animal model of amyloid deposition. Impaired phagocytosis is not innate, and develops only at later stages of amyloidosis. Furthermore, we show that membrane currents induced by uridine diphosphate, a ligand activating P2Y6 receptors, are altered in response rate and amplitude in microglia in close vicinity to plaques, but not in plaque-free areas of 5xFAD animals. These changes were accompanied by changes in membrane properties and potassium channel activity of plaque-associated microglia in early and late stages of amyloidosis. As a conclusion, the physiological properties of plaque-associated microglia are altered with a strong impact on purinergic signaling.