Prion protein monoclonal antibody (PRN100) therapy for Creutzfeldt-Jakob disease: evaluation of a first-in-human treatment programme.

BACKGROUND: Human prion diseases, including Creutzfeldt-Jakob disease (CJD), are rapidly progressive, invariably fatal neurodegenerative conditions with no effective therapies. Their pathogenesis involves the obligate recruitment of cellular prion protein (PrPC) into self-propagating multimeric assemblies or prions. Preclinical studies have firmly validated the targeting of PrPC as a therapeutic strategy. We aimed to evaluate a first-in-human treatment programme using an anti-PrPC monoclonal antibody under a Specials Licence. METHODS: We generated a fully humanised anti-PrPC monoclonal antibody (an IgG4κ isotype; PRN100) for human use. We offered treatment with PRN100 to six patients with a clinical diagnosis of probable CJD who were not in the terminal disease stages at the point of first assessment and who were able to readily travel to the University College London Hospital (UCLH) Clinical Research Facility, London, UK, for treatment. After titration (1 mg/kg and 10 mg/kg at 48-h intervals), patients were treated with 80-120 mg/kg of intravenous PRN100 every 2 weeks until death or withdrawal from the programme, or until the supply of PRN100 was exhausted, and closely monitored for evidence of adverse effects. Disease progression was assessed by use of the Medical Research Council (MRC) Prion Disease Rating Scale, Motor Scale, and Cognitive Scale, and compared with that of untreated natural history controls (matched for disease severity, subtype, and PRNP codon 129 genotype) recruited between Oct 1, 2008, and July 31, 2018, from the National Prion Monitoring Cohort study. Autopsies were done in two patients and findings were compared with those from untreated natural history controls. FINDINGS: We treated six patients (two men; four women) with CJD for 7-260 days at UCLH between Oct 9, 2018, and July 31, 2019. Repeated intravenous dosing of PRN100 was well tolerated and reached the target CSF drug concentration (50 nM) in four patients after 22-70 days; no clinically significant adverse reactions were seen. All patients showed progressive neurological decline on serial assessments with the MRC Scales. Neuropathological examination was done in two patients (patients 2 and 3) and showed no evidence of cytotoxicity. Patient 2, who was treated for 140 days, had the longest clinical duration we have yet documented for iatrogenic CJD and showed patterns of disease-associated PrP that differed from untreated patients with CJD, consistent with drug effects. Patient 3, who had sporadic CJD and only received one therapeutic dose of 80 mg/kg, had weak PrP synaptic labelling in the periventricular regions, which was not a feature of untreated patients with sporadic CJD. Brain tissue-bound drug concentrations across multiple regions in patient 2 ranged from 9·9 µg per g of tissue (SD 0·3) in the thalamus to 27·4 µg per g of tissue (1·5) in the basal ganglia (equivalent to 66-182 nM). INTERPRETATION: Our academic-led programme delivered what is, to our knowledge, the first rationally designed experimental treatment for human prion disease to a small number of patients with CJD. The treatment appeared to be safe and reached encouraging CSF and brain tissue concentrations. These findings justify the need for formal efficacy trials in patients with CJD at the earliest possible clinical stages and as prophylaxis in those at risk of prion disease due to PRNP mutations or prion exposure. FUNDING: The Cure CJD Campaign, the National Institute for Health Research UCLH Biomedical Research Centre, the Jon Moulton Charitable Trust, and the UK MRC.

Targeting early changes in the synovial microenvironment: a new class of immunomodulatory therapy?

OBJECTIVES: Controlled immune responses rely on integrated crosstalk between cells and their microenvironment. We investigated whether targeting proinflammatory signals from the extracellular matrix that persist during pathological inflammation provides a viable strategy to treat rheumatoid arthritis (RA). METHODS: Monoclonal antibodies recognising the fibrinogen-like globe (FBG) of tenascin-C were generated by phage display. Clones that neutralised FBG activation of toll-like receptor 4 (TLR4), without impacting pathogenic TLR4 activation, were epitope mapped by crystallography. Antibodies stained synovial biopsies of patients at different stages of RA development. Antibody efficacy in preventing RA synovial cell cytokine release, and in modulating collagen-induced arthritis in rats, was assessed. RESULTS: Tenascin-C is expressed early in the development of RA, even before disease diagnosis, with higher levels in the joints of people with synovitis who eventually developed RA than in people whose synovitis spontaneously resolved. Anti-FBG antibodies inhibited cytokine release by RA synovial cells and prevented disease progression and tissue destruction during collagen-induced arthritis. CONCLUSIONS: Early changes in the synovial microenvironment contribute to RA progression; blocking proinflammatory signals from the matrix can ameliorate experimental arthritis. These data highlight a new drug class that could offer early, disease-specific immune modulation in RA, without engendering global immune suppression.

Peptidomics: A new approach to affinity protein microarrays.

Protein microarrays for diagnostic and proteomic analyses are being developed using a number of different techniques for each of the steps required including immobilisation methods, assay and detection systems. This is extremely different to the development of DNA microarrays which is now a well established technology that has demonstrated the capabilities of transcriptomics to deliver validated differential transcripts. As mRNA and protein levels do not always correlate, protein microarrays would seem to be an obvious successor to DNA arrays. Unlike nucleic acids, however, protein targets are typically nonhomogeneous in physicochemical properties and affinity capture agents are often poorly characterised making the experiments difficult to perfect and reproduce. Moreover, running multiple affinity assays in parallel (multiplexing) is compromised by the heterogeneity of antibody affinities to their protein targets. In the peptidomic approach presented here the assayed mixture of proteins is enzymatically digested prior to affinity capture to form a mixture of short peptides that are more similar in their physicochemical properties than intact proteins. These peptides can be predicted by in silico digestion of individual proteins, e.g. from protein databases allowing design of nonhomologous reagents for the screening of affinity agent libraries. The use of mass spectrometry (e.g. matrix-assisted laser desorption/ionization-time of flight mass spectrometry) for a direct confirmation of the identity of the species captured, provides a further advantage compared to the more usual method of detection in which fluorescently labelled captured species are scanned to give a spatially resolved image of the array.

A bovine whole-genome radiation hybrid panel and outline map.

A 3000-rad radiation hybrid panel was constructed for cattle and used to build outline RH maps for all 29 autosomes and the X and Y chromosomes. These outline maps contain about 1200 markers, most of which are anonymous microsatellite loci. Comparisons between the RH chromosome maps, other published RH maps, and linkage maps allow regions of chromosomes that are poorly mapped or that have sparse marker coverage to be identified. In some cases, mapping ambiguities can be resolved. The RH maps presented here are the starting point for mapping additional loci, in particular genes and ESTs that will allow detailed comparative maps between cattle and other species to be constructed. Radiation hybrid cell panels allow high-density genetic maps to be constructed, with the advantage over linkage mapping that markers do not need to be polymorphic. A large quantity of DNA has been prepared from the cells forming the RH panel reported here and is publicly available for mapping large numbers of loci.