Generation of helper virus-free adeno-associated viral vector packaging/producer cell lines based on a human suspension cell line

The emerging number of clinical trials in the gene therapy field poses the challenge to the industry to produce viral vectors in a scalable, reproducible and cost-efficient manner. To address this issue, our CAP-GT platform comprises high density, serum free suspension cell lines that enable reproducible, scalable transfection and high titer production of viral vectors. An adeno-associated virus (AAV) based vector was the first approved gene therapy product in clinical applications. Attractive features of AAV as a gene therapy vector are e.g. its lack of pathogenicity and its ability to transduce dividing and non-dividing cells. Moving away from mainly targeting ultra-rare diseases and taking more common indications into focus will need to see significant improvements concerning productivity and consistent quality of AAV vector production in order to ensure supply. For this purpose, we are developing a helper virus-free packaging cell line that can easily be turned into a producer cell line by only one additional step of cell line development. Base of this packing cell line is the generation of a cell line with stable Tet-inducible expression of Rep proteins. Extensive screening of Rep expressing single cell clones resulted in clonal cell lines which produced high AAV titers upon induction and transfection of the missing components. In a next step, the adenoviral helper functions E2A and E4orf6 are introduced, due to their toxicity also under the control of a Tet-inducible promoter. In addition, the VA RNA is encoded by the same construct. Finally, a Tet-inducible capsid function and GFP as transgene flanked by the ITRs combined on one construct will be stably integrated resulting in a proof of principle producer cell line. This approach should enable a consistent quality production of AAV vectors that abolishes the drawbacks of transient transfection concerning reproducibility, consistency and high costs for GMP-grade DNA. Process optimization in regard to process duration, feeding strategy etc. is currently ongoing for further improving the vector yields

Engineering of exosomes for targeted delivery of therapeutic microRNAs

Exosomes are small membrane vesicles secreted from most cell types. They contain a range of proteins, lipids, mRNAs and microRNAs (miRNA) and are naturally taken up by cells in order to deliver these contents to recipient cells. Increased understanding of this process as well as advances in bioengineering has led to investigations into the use of exosomes as targeted vehicles to transport therapeutic non-coding RNAs, proteins or drug molecules directly across cellular barriers into recipient cells. miRNAs are small non-coding RNA molecules, which play a key role in mediating biological function due to their prominent role in gene regulation. Deregulation of miRNAs is a common feature in cancer, suggesting that these molecules could serve as targets for therapeutic intervention by restoring or inhibiting their cellular function. However, various biological barriers including in vivo nuclease degradation, fibrous nature of tumors, and miRNA-induced immune response drastically hinder their bioavailability. In the context of these complex settings, exosomal delivery may display a novel strategy for targeted delivery of RNA therapeutics. We have recently identified and characterized novel pro-apoptotic miRNAs (Kleemann et al 2016, Flum et al 2017), which are down-regulated in cancer cells suggesting promising potential for therapeutic approaches. In the current study we conducted an initial evaluation of the novel concept to enable targeted delivery of small therapeutic RNAs using exosomes as biological transport systems. CEVECs amniocyte production cells (CAP) are utile human expression hosts highly suitable for the production of glycosylated biotherapeutic proteins. However, there are currently no reports as to whether this human cell line may as well produce extracellular vesicles suitable for targeted delivery of therapeutics. In order to evaluate these cells as production hosts for exosomes, we initially cultivated parental CAP cells and were able to isolate exosomes by centrifugation. Exosomal preparations were examined for vesicle identity, size, morphology and concentration using dynamic light scattering, flow cytometry, western blotting and electron microscopy. In order to be able to visualize exosomes and track targeted delivery in subsequent experiments, we engineered CAP cells to stably overexpress a CD63-GFP-fusion protein. This overexpression of a fluorescent transmembrane protein present on exosomes enabled the tracing of produced exosomes using flow cytometry. To functionally analyze isolated exosomes regarding their potential to delivery small therapeutic agents, these fluorescently labeled exosomes were further engineered to overexpress therapeutic, pro-apoptotic and control miRNAs by stable genome integration into CAP parental cells. Resulting preparations of engineered exosomes were analyzed for modified miRNA content in comparison to parental cells using qPCR. Currently the cells are further engineered to overexpress modified surface receptors to facilitate targeted uptake by tumor cells. Fluorescently labelled exosomes carrying therapeutic miRNAs and surface receptors will finally be co-cultured with target cells to analyze the potential of engineered exosomes to crossing membrane barriers and reliably deliver therapeutic miRNAs to recipient cells. The current study pursues the novel therapeutic concept of using exosomes as delivery vehicle for small non-coding RNAs molecules. We present data which assess for the first time the potential application of exosomes produced by a human production host for biotherapeutics. In addition to these current engineering and delivery approaches, future application of this cell therapy will heavily depend upon mass production of these delivery vectors and production issues will therefore gain increasing importance. Kleemann M, Bereuther J, Fischer S, Marquart K, Hänle S, Unger K, Jendrossek V, Riedel C, Handrick R, Otte K (2016) Investigation on tissue specific effects of pro-apoptotic miR-147b as a potential biomarker in ovarian cancer prognosis. Oncotarget 8 (12), 18773-18791 Flum M, Kleemann M, Schneider H, Weis B, Fischer S, Handrick R, Otte K (2017) miR-217-5p induces apoptosis by directly targeting PRKCI, BAG3, ITGAV and MAPK1 in colorectal cancer cells. J Cell Commun Signal, doi: 10.1007/s12079-017-0410-x

A novel panel of mouse models to evaluate the role of human pregnane X receptor and constitutive androstane receptor in drug response

The pregnane X receptor (PXR) and the constitutive androstane receptor (CAR) are closely related orphan nuclear hormone receptors that play a critical role as xenobiotic sensors in mammals. Both receptors regulate the expression of genes involved in the biotransformation of chemicals in a ligand-dependent manner. As the ligand specificity of PXR and CAR have diverged between species, the prediction of in vivo PXR and CAR interactions with a drug are difficult to extrapolate from animals to humans. We report the development of what we believe are novel PXR- and CAR-humanized mice, generated using a knockin strategy, and Pxr- and Car-KO mice as well as a panel of mice including all possible combinations of these genetic alterations. The expression of human CAR and PXR was in the predicted tissues at physiological levels, and splice variants of both human receptors were expressed. The panel of mice will allow the dissection of the crosstalk between PXR and CAR in the response to different drugs. To demonstrate the utility of this panel of mice, we used the mice to show that the in vivo induction of Cyp3a11 and Cyp2b10 by phenobarbital was only mediated by CAR, although this compound is described as a PXR and CAR activator in vitro. This panel of mouse models is a useful tool to evaluate the roles of CAR and PXR in drug bioavailability, toxicity, and efficacy in humans

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Evolutionary consequences of feedbacks between within-host competition and disease control

Lay Summary: Competition often occurs among diverse parasites within a single host, but control efforts could change its strength. We examined how the interplay between competition and control could shape the evolution of parasite traits like drug resistance and disease severity

Bleeding and thrombotic risk in pregnant women with Fontan physiology

Background/objectives Pregnancy may potentiate the inherent hypercoagulability of the Fontan circulation, thereby amplifying adverse events. This study sought to evaluate thrombosis and bleeding risk in pregnant women with a Fontan.  Methods We performed a retrospective observational cohort study across 13 international centres and recorded data on thrombotic and bleeding events, antithrombotic therapies and pre-pregnancy thrombotic risk factors.  Results We analysed 84 women with Fontan physiology undergoing 108 pregnancies, average gestation 33 +/- 5 weeks. The most common antithrombotic therapy in pregnancy was aspirin (ASA, 47 pregnancies (43.5%)). Heparin (unfractionated (UFH) or low molecular weight (LMWH)) was prescribed in 32 pregnancies (30%) and vitamin K antagonist (VKA) in 10 pregnancies (9%). Three pregnancies were complicated by thrombotic events (2.8%). Thirty-eight pregnancies (35%) were complicated by bleeding, of which 5 (13%) were severe. Most bleeds were obstetric, occurring antepartum (45%) and postpartum (42%). The use of therapeutic heparin (OR 15.6, 95% CI 1.88 to 129, p=0.006), VKA (OR 11.7, 95% CI 1.06 to 130, p=0.032) or any combination of anticoagulation medication (OR 13.0, 95% CI 1.13 to 150, p=0.032) were significantly associated with bleeding events, while ASA (OR 5.41, 95% CI 0.73 to 40.4, p=0.067) and prophylactic heparin were not (OR 4.68, 95% CI 0.488 to 44.9, p=0.096). Conclusions Current antithrombotic strategies appear effective at attenuating thrombotic risk in pregnant women with a Fontan. However, this comes with high (>30%) bleeding risk, of which 13% are life threatening. Achieving haemostatic balance is challenging in pregnant women with a Fontan, necessitating individualised risk-adjusted counselling and therapeutic approaches that are monitored during the course of pregnancy

The genomic and transcriptional landscape of primary central nervous system lymphoma

Primary lymphomas of the central nervous system (PCNSL) are mainly diffuse large B-cell lymphomas (DLBCLs) confined to the central nervous system (CNS). Molecular drivers of PCNSL have not been fully elucidated. Here, we profile and compare the whole-genome and transcriptome landscape of 51 CNS lymphomas (CNSL) to 39 follicular lymphoma and 36 DLBCL cases outside the CNS. We find recurrent mutations in JAK-STAT, NFkB, and B-cell receptor signaling pathways, including hallmark mutations in MYD88 L265P (67%) and CD79B (63%), and CDKN2A deletions (83%). PCNSLs exhibit significantly more focal deletions of HLA-D (6p21) locus as a potential mechanism of immune evasion. Mutational signatures correlating with DNA replication and mitosis are significantly enriched in PCNSL. TERT gene expression is significantly higher in PCNSL compared to activated B-cell (ABC)-DLBCL. Transcriptome analysis clearly distinguishes PCNSL and systemic DLBCL into distinct molecular subtypes. Epstein-Barr virus (EBV)+ CNSL cases lack recurrent mutational hotspots apart from IG and HLA-DRB loci. We show that PCNSL can be clearly distinguished from DLBCL, having distinct expression profiles, IG expression and translocation patterns, as well as specific combinations of genetic alterations

Effect of priming interval on reactogenicity, peak immunological response, and waning after homologous and heterologous COVID-19 vaccine schedules: exploratory analyses of Com-COV, a randomised control trial

BackgroundPriming COVID-19 vaccine schedules have been deployed at variable intervals globally, which might influence immune persistence and the relative importance of third-dose booster programmes. Here, we report exploratory analyses from the Com-COV trial, assessing the effect of 4-week versus 12-week priming intervals on reactogenicity and the persistence of immune response up to 6 months after homologous and heterologous priming schedules using the vaccines BNT162b2 (tozinameran, Pfizer/BioNTech) and ChAdOx1 nCoV-19 (AstraZeneca).MethodsCom-COV was a participant-masked, randomised immunogenicity trial. For these exploratory analyses, we used the trial's general cohort, in which adults aged 50 years or older were randomly assigned to four homologous and four heterologous vaccine schedules using BNT162b2 and ChAdOx1 nCoV-19 with 4-week or 12-week priming intervals (eight groups in total). Immunogenicity analyses were done on the intention-to-treat (ITT) population, comprising participants with no evidence of SARS-CoV-2 infection at baseline or for the trial duration, to assess the effect of priming interval on humoral and cellular immune response 28 days and 6 months post-second dose, in addition to the effects on reactogenicity and safety. The Com-COV trial is registered with the ISRCTN registry, 69254139 (EudraCT 2020–005085–33).FindingsBetween Feb 11 and 26, 2021, 730 participants were randomly assigned in the general cohort, with 77–89 per group in the ITT analysis. At 28 days and 6 months post-second dose, the geometric mean concentration of anti-SARS-CoV-2 spike IgG was significantly higher in the 12-week interval groups than in the 4-week groups for homologous schedules. In heterologous schedule groups, we observed a significant difference between intervals only for the BNT162b2–ChAdOx1 nCoV-19 group at 28 days. Pseudotyped virus neutralisation titres were significantly higher in all 12-week interval groups versus 4-week groups, 28 days post-second dose, with geometric mean ratios of 1·4 (95% CI 1·1–1·8) for homologous BNT162b2, 1·5 (1·2–1·9) for ChAdOx1 nCoV-19–BNT162b2, 1·6 (1·3–2·1) for BNT162b2–ChAdOx1 nCoV-19, and 2·4 (1·7–3·2) for homologous ChAdOx1 nCoV-19. At 6 months post-second dose, anti-spike IgG geometric mean concentrations fell to 0·17–0·24 of the 28-day post-second dose value across all eight study groups, with only homologous BNT162b2 showing a slightly slower decay for the 12-week versus 4-week interval in the adjusted analysis. The rank order of schedules by humoral response was unaffected by interval, with homologous BNT162b2 remaining the most immunogenic by antibody response. T-cell responses were reduced in all 12-week priming intervals compared with their 4-week counterparts. 12-week schedules for homologous BNT162b2 and ChAdOx1 nCoV-19–BNT162b2 were up to 80% less reactogenic than 4-week schedules.InterpretationThese data support flexibility in priming interval in all studied COVID-19 vaccine schedules. Longer priming intervals might result in lower reactogenicity in schedules with BNT162b2 as a second dose and higher humoral immunogenicity in homologous schedules, but overall lower T-cell responses across all schedules. Future vaccines using these novel platforms might benefit from schedules with long intervals

Safety and immunogenicity of heterologous versus homologous prime-boost schedules with an adenoviral vectored and mRNA COVID-19 vaccine (Com-COV): a single-blind, randomised, non-inferiority trial

Background: Use of heterologous prime-boost COVID-19 vaccine schedules could facilitate mass COVID-19 immunisation. However, we have previously reported that heterologous schedules incorporating an adenoviral vectored vaccine (ChAdOx1 nCoV-19, AstraZeneca; hereafter referred to as ChAd) and an mRNA vaccine (BNT162b2, Pfizer–BioNTech; hereafter referred to as BNT) at a 4-week interval are more reactogenic than homologous schedules. Here, we report the safety and immunogenicity of heterologous schedules with the ChAd and BNT vaccines. Methods: Com-COV is a participant-blinded, randomised, non-inferiority trial evaluating vaccine safety, reactogenicity, and immunogenicity. Adults aged 50 years and older with no or well controlled comorbidities and no previous SARS-CoV-2 infection by laboratory confirmation were eligible and were recruited at eight sites across the UK. The majority of eligible participants were enrolled into the general cohort (28-day or 84-day prime-boost intervals), who were randomly assigned (1:1:1:1:1:1:1:1) to receive ChAd/ChAd, ChAd/BNT, BNT/BNT, or BNT/ChAd, administered at either 28-day or 84-day prime-boost intervals. A small subset of eligible participants (n=100) were enrolled into an immunology cohort, who had additional blood tests to evaluate immune responses; these participants were randomly assigned (1:1:1:1) to the four schedules (28-day interval only). Participants were masked to the vaccine received but not to the prime-boost interval. The primary endpoint was the geometric mean ratio (GMR) of serum SARS-CoV-2 anti-spike IgG concentration (measured by ELISA) at 28 days after boost, when comparing ChAd/BNT with ChAd/ChAd, and BNT/ChAd with BNT/BNT. The heterologous schedules were considered non-inferior to the approved homologous schedules if the lower limit of the one-sided 97·5% CI of the GMR of these comparisons was greater than 0·63. The primary analysis was done in the per-protocol population, who were seronegative at baseline. Safety analyses were done among participants receiving at least one dose of a study vaccine. The trial is registered with ISRCTN, 69254139. Findings: Between Feb 11 and Feb 26, 2021, 830 participants were enrolled and randomised, including 463 participants with a 28-day prime-boost interval, for whom results are reported here. The mean age of participants was 57·8 years (SD 4·7), with 212 (46%) female participants and 117 (25%) from ethnic minorities. At day 28 post boost, the geometric mean concentration of SARS-CoV-2 anti-spike IgG in ChAd/BNT recipients (12 906 ELU/mL) was non-inferior to that in ChAd/ChAd recipients (1392 ELU/mL), with a GMR of 9·2 (one-sided 97·5% CI 7·5 to ∞). In participants primed with BNT, we did not show non-inferiority of the heterologous schedule (BNT/ChAd, 7133 ELU/mL) against the homologous schedule (BNT/BNT, 14 080 ELU/mL), with a GMR of 0·51 (one-sided 97·5% CI 0·43 to ∞). Four serious adverse events occurred across all groups, none of which were considered to be related to immunisation. Interpretation: Despite the BNT/ChAd regimen not meeting non-inferiority criteria, the SARS-CoV-2 anti-spike IgG concentrations of both heterologous schedules were higher than that of a licensed vaccine schedule (ChAd/ChAd) with proven efficacy against COVID-19 disease and hospitalisation. Along with the higher immunogenicity of ChAd/BNT compared with ChAD/ChAd, these data support flexibility in the use of heterologous prime-boost vaccination using ChAd and BNT COVID-19 vaccines. Funding: UK Vaccine Task Force and National Institute for Health Research