Combination of the Glutaminyl Cyclase Inhibitor PQ912 (Varoglutamstat) and the Murine Monoclonal Antibody PBD-C06 (m6) Shows Additive Effects on Brain Aß Pathology in Transgenic Mice.

Compelling evidence suggests that pyroglutamate-modified Aß (pGlu3-Aß; AßN3pG) peptides play a pivotal role in the development and progression of Alzheimer's disease (AD). Approaches targeting pGlu3-Aß by glutaminyl cyclase (QC) inhibition (Varoglutamstat) or monoclonal antibodies (Donanemab) are currently in clinical development. Here, we aimed at an assessment of combination therapy of Varoglutamstat (PQ912) and a pGlu3-Aß-specific antibody (m6) in transgenic mice. Whereas the single treatments at subtherapeutic doses show moderate (16-41%) but statistically insignificant reduction of Aß42 and pGlu-Aß42 in mice brain, the combination of both treatments resulted in significant reductions of Aß by 45-65%. Evaluation of these data using the Bliss independence model revealed a combination index of ≈1, which is indicative for an additive effect of the compounds. The data are interpreted in terms of different pathways, in which the two drugs act. While PQ912 prevents the formation of pGlu3-Aß in different compartments, the antibody is able to clear existing pGlu3-Aß deposits. The results suggest that combination of the small molecule Varoglutamstat and a pE3Aß-directed monoclonal antibody may allow a reduction of the individual compound doses while maintaining the therapeutic effect.

Role of complement activation and disruption of the blood-brain barrier in the pathogenesis of multiple system atrophy.

Multiple system atrophy (MSA) is a progressive and sporadic neurodegenerative disorder characterized by the histological appearance of glial cytoplasmic inclusions primarily composed of α-synuclein. Recently, complement-mediated neuroinflammation has been proposed as a key factor in the pathogenesis of numerous neurodegenerative disorders. We conducted immunohistochemical/immunofluorescent assays targeting a number of complements to explore the role of complements in MSA pathogenesis using brain samples from deceased patients and controls. Complement deposition was notably increased in the cerebral vasculature and myelin sheath in the MSA brains. Furthermore, fibrinogen leakage resulting from the disruption of the blood-brain barrier (BBB) was observed, along with the presence of C1q-positive microglia clusters surrounding the MSA brain vessels. These immunohistochemical/immunofluorescent findings suggest that complement activation and BBB disruption play critical roles in MSA progression.

Erythema nodosum-like eruption in coronavirus disease 2019: A case report and literature review of Asian countries.

In the worldwide coronavirus disease 2019 (COVID-19) outbreak, skin manifestations were seen in COVID-19 patients. We report a case in which a COVID-19 patient developed cutaneous lesions that were diagnosed as erythema nodosum-like lesions, which were associated with COVID-19. Nasopharyngeal swab polymerase chain reaction (PCR) confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Histopathologically, extensive inflammation was seen from the epidermis to the fat tissue. An organized thrombus and disrupted inner elastic lamina were seen in an intradermal vessel. These findings suggest septal panniculitis with cutaneous polyarteritis nodosa. The results of PCR using the specimen of skin lesion was negative. The patient took non-steroidal anti-inflammatory drugs and the skin lesion improved in 3 weeks. To characterize the skin eruption, we reviewed previous reports on COVID-19 (confirmed by the detection of SARS-CoV-2 infection) from Asian countries. The type of eruption and timing of its appearance in this case seemed rare. Differences in skin manifestations between Western and Asian countries were noted.

Development of the clinical candidate PBD-C06, a humanized pGlu3-Aß-specific antibody against Alzheimer's disease with reduced complement activation.

In clinical trials with early Alzheimer's patients, administration of anti-amyloid antibodies reduced amyloid deposits, suggesting that immunotherapies may be promising disease-modifying interventions against Alzheimer's disease (AD). Specific forms of amyloid beta (Aß) peptides, for example post-translationally modified Aß peptides with a pyroglutamate at the N-terminus (pGlu3, pE3), are attractive antibody targets, due to pGlu3-Aß's neo-epitope character and its propensity to form neurotoxic oligomeric aggregates. We have generated a novel anti-pGlu3-Aß antibody, PBD-C06, which is based on a murine precursor antibody that binds with high specificity to pGlu3-Aß monomers, oligomers and fibrils, including mixed aggregates of unmodified Aß and pGlu3-Aß peptides. PBD-C06 was generated by first grafting the murine antigen binding sequences onto suitable human variable light and heavy chains. Subsequently, the humanized antibody was de-immunized and site-specific mutations were introduced to restore original target binding, to eliminate complement activation and to improve protein stability. PBD-C06 binds with the same specificity and avidity as its murine precursor antibody and elimination of C1q binding did not compromise Fcγ-receptor binding or in vitro phagocytosis. Thus, PBD-C06 was specifically designed to target neurotoxic aggregates and to avoid complement-mediated inflammatory responses, in order to lower the risk for vasogenic edemas in the clinic.