Strong evidence exists for a central role of amyloid β-protein (Aβ) oligomers in the pathogenesis of Alzheimer’s disease. We have developed a fast, reliable and robust in vitro assay, termed QIAD, to quantify the effect of any compound on the Aβ aggregate size distribution. Applying QIAD, we studied the effect of homotaurine, scyllo-inositol, EGCG, the benzofuran derivative KMS88009, ZAβ3W, the D-enantiomeric peptide D3 and its tandem version D3D3 on Aβ aggregation. The predictive power of the assay for in vivo efficacy is demonstrated by comparing the oligomer elimination efficiency of D3 and D3D3 with their treatment effects in animal models of Alzheimer´s disease.

While amyloid-β protein (Aβ) aggregation into insoluble plaques is one of the pathological hallmarks of Alzheimer’s disease (AD), soluble oligomeric Aβ has been hypothesized to be responsible for synapse damage, neurodegeneration, learning, and memory deficits in AD. Here, we investigate the in vitro and in vivo efficacy of the d-enantiomeric peptide RD2, a rationally designed derivative of the previously described lead compound D3, which has been developed to efficiently eliminate toxic Aβ42 oligomers as a promising treatment strategy for AD. Besides the detailed in vitro characterization of RD2, we also report the results of a treatment study of APP/PS1 mice with RD2. After 28 days of treatment we observed enhancement of cognition and learning behaviour. Analysis on brain plaque load did not reveal significant changes, but a significant reduction of insoluble Aβ42. Our findings demonstrate that RD2 was significantly more efficient in Aβ oligomer elimination in vitro compared to D3. Enhanced cognition without reduction of plaque pathology in parallel suggests that synaptic malfunction due to Aβ oligomers rather than plaque pathology is decisive for disease development and progression. Thus, Aβ oligomer elimination by RD2 treatment may be also beneficial for AD patients.

The protein B of group B streptococci can bind in a nonimmune reaction to Ig of the IgG and IgM classes of various mammalian species (i.e., human, mouse, rabbit, and bovine). Protein B binding involves the Fc parts of both IgG and IgM molecules. Monoclonal or polyclonal IgG or IgM and the IgM-FC5 mu fragment of human myeloma protein combined with the protein B thereby inhibiting protein B-induced hemolysis in the CAMP reaction. The protein B/Ig complex can be dissociated with 1% Triton or guanidine-HCl (6 M). Mice infected intraperitoneally with sublethal doses of group B streptococci (GBS) and that received seven repeated intravenous injections of highly purified protein B during the first 9 h of infection developed fatal septicemia within 24 h with colony counts of up to 10(8) CFU/ml in the blood. Animals treated in the same way with either PBS or trypsinized protein B recovered. The protein B itself was not pathogenic when injected into healthy mice. Tissue sections of liver or spleen from mice infected with a lethal dose of GBS revealed the presence of protein B together with large numbers of cocci when stained by the peroxidase method using specific antibodies raised against purified protein B in the rabbit.

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder that is associated with the aggregation of the amyloid β protein (Aβ). Aβ oligomers are currently thought to be the major neurotoxic agent responsible for disease development and progression. Thus, their elimination is highly desirable for therapy development. Our therapeutic approach aims at specific and direct elimination of toxic Aβ oligomers by stabilizing Aβ monomers in an aggregation-incompetent conformation. We have proven that our lead compound “D3”, an all d-enantiomeric-peptide, specifically eliminates Aβ oligomers in vitro. In vivo, D3 enhances cognition and reduces plaque load in several transgenic AD mouse models. Here, we performed a large-scale oral proof of concept efficacy study, in which we directly compared four of the most promising D3-derivatives in transgenic mice expressing human amyloid precursor protein with Swedish and London mutations (APPSL), transgenic mice, to identify the most effective compound. RD2 and D3D3, both derived from D3 by rational design, were discovered to be the most effective derivatives in improving cognition in the Morris water maze. The performance of RD2- and D3D3-treated mice within the Morris water maze was significantly better than placebo-treated mice and, importantly, nearly as good as those of non-transgenic littermates, suggesting a complete reversal of the cognitive deficit of APPSL mice.

Introduction PRI‐002 is an orally available anti–amyloid beta (Aβ) prionic compound developed for direct disassembly of toxic Aβ oligomers relevant to Alzheimer's disease. Methods Two placebo‐controlled clinical phase I trials with oral dosing of PRI‐002 were conducted in healthy young subjects: A single ascending dose trial (4, 12, 36, 108, or 320 mg PRI‐002 or placebo) in 40 participants followed by a multiple ascending dose study with daily 160 mg PRI‐002 for 14 days or 320 mg for 28 days in 24 participants. The main objectives were safety, tolerability, and evaluation of pharmacokinetic (PK) parameters. Results PRI‐002 was safe and well tolerated after single and multiple oral administration up to the highest doses. PRI‐002 was absorbed rapidly and drug exposure increased proportional to dose. During repeated daily administration, the drug accumulated by a factor of about three. Steady‐state conditions were reached after 1 to 2 weeks. Conclusions The safety and PK results encourage further clinical development of PRI‐002.