First-in-human assessment of PRX002, an anti-α-synuclein monoclonal antibody, in healthy volunteers.

BACKGROUND: α-Synuclein is a major component of pathologic inclusions that characterize Parkinson's disease. PRX002 is an antibody that targets α-synuclein, and its murine parent antibody 9E4 has been shown in preclinical studies to reduce α-synuclein pathology and to protect against cognitive and motor deteriorations and progressive neurodegeneration in human α-synuclein transgenic mice. METHODS: This first-in-human, randomized, double-blind, placebo-controlled, phase 1 study assessed the impact of PRX002 administered to 40 healthy participants in 5 ascending-dose cohorts (n = 8/cohort) in which participants were randomly assigned to receive a single intravenous infusion of study drug (0.3, 1, 3, 10, or 30 mg/kg; n = 6/cohort) or placebo (n = 2/cohort). RESULTS: PRX002 demonstrated favorable safety, tolerability, and pharmacokinetic profiles at all doses tested, with no immunogenicity. No serious adverse events, discontinuations as a result of adverse events, or dose-limiting toxicities were reported. Serum PRX002 exposure was dose proportional; the average terminal half-life across all doses was 18.2 days. A significant dose-dependent reduction in free serum α-synuclein (unbound to PRX002) was apparent within 1 hour after PRX002 administration, whereas total α-synuclein (free plus bound) increased dose-dependently, presumably because of the expected change in kinetics following antibody binding. CONCLUSIONS: This study demonstrates that serum α-synuclein can be safely modulated in a dose-dependent manner after single intravenous infusions of an anti-α-synuclein antibody. These findings support continued development of PRX002, including further characterization of its safety, tolerability, pharmacokinetics, and pharmacodynamic effects in the central nervous system in patients with Parkinson's disease. © 2016 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Safety and Tolerability of Multiple Ascending Doses of PRX002/RG7935, an Anti-α-Synuclein Monoclonal Antibody, in Patients With Parkinson Disease: A Randomized Clinical Trial.

Importance: Aggregated α-synuclein is believed to be central to the pathogenesis of Parkinson disease (PD). PRX002/RG7935 (PRX002) is a humanized monoclonal antibody designed to target aggregated forms of α-synuclein, thereby inhibiting neuron-to-neuron transfer of presumed pathogenic forms of α-synuclein, potentially resulting in neuronal protection and slowing disease progression. Objective: To evaluate the safety and tolerability of multiple intravenous infusions of PRX002 in patients with idiopathic PD. Design, Setting, and Participants: Multicenter, randomized, double-blind, placebo-controlled, multiple ascending-dose trial at 8 US study centers from July 2014 to September 2016. Eligible participants were aged 40 to 80 years with mild to moderate idiopathic PD (Hoehn and Yahr stages 1-3). Interventions: Participants were enrolled into 6 ascending-dose cohorts and randomly assigned to receive PRX002 (0.3 mg/kg, 1.0 mg/kg, 3.0 mg/kg, 10 mg/kg, 30 mg/kg, or 60 mg/kg) or placebo. Participants received 3 intravenous infusions every 4 weeks of PRX002 or placebo and were monitored during a 24-week observational period. Main Outcomes and Measures: Safety and tolerability assessments included physical and neurological examinations, laboratory tests, vital signs, and adverse events. Pharmacokinetic parameters included maximum PRX002 concentration, area under the curve, and half-life. Results: Of the 80 participants, most were white (97.5%; n = 78) and male (80%; n = 64); median (SD) age was 58 (8.4) years. PRX002 was generally safe and well tolerated; no serious or severe PRX002-related treatment-emergent adverse events (TEAEs) were reported. The TEAEs experienced by at least 5% of patients receiving PRX002, irrespective of relatedness to study drug, were constipation (9.1%; n = 5), infusion reaction (7.3%; n = 4), diarrhea (5.5%; n = 3), headache (5.5%; n = 3), peripheral edema (5.5%; n = 3), post-lumbar puncture syndrome (5.5%; n = 3), and upper respiratory tract infection (5.5%; n = 3). No antidrug antibodies were detected. Serum PRX002 levels increased in an approximately dose-proportional manner; mean terminal elimination half-life was similar across all doses (10.2 days). Rapid dose- and time-dependent mean reductions from baseline vs placebo in free serum α-synuclein levels of up to 97% were seen after a single infusion at the highest dose (F78,284 = 1.66; P = .002), with similar reductions after 2 additional infusions. Mean cerebrospinal fluid PRX002 concentration increased with PRX002 dose and was approximately 0.3% relative to serum across all dose cohorts. Conclusions and Relevance: Single and multiple doses of PRX002 were generally safe and well tolerated and resulted in robust binding of peripheral α-synuclein and dose-dependent increases of PRX002 in cerebrospinal fluid, reaching cerebrospinal fluid concentrations that may be expected to engage extracellular aggregated α-synuclein in the brain. Findings support the design of an ongoing phase 2 clinical study (NCT03100149). Trial Registration: ClinicalTrials.gov Identifier: NCT02157714.

First-in-Human Phase I/II Study of NEOD001 in Patients With Light Chain Amyloidosis and Persistent Organ Dysfunction.

PURPOSE: Light chain (AL) amyloidosis is caused by the accumulation of misfolded proteins, which induces the dysfunction of vital organs. NEOD001 is a monoclonal antibody targeting these misfolded proteins. We report interim data from a phase I/II dose-escalation/expansion study of NEOD001 in patients with AL amyloidosis and persistent organ dysfunction (NCT01707264). PATIENTS AND METHODS: Patients who had completed at least one previous anti-plasma cell-directed therapy, had partial hematologic response or better, and had persistent organ dysfunction received NEOD001 intravenously every 28 days. Dose levels of 0.5, 1, 2, 4, 8, 16, and 24 mg/kg were evaluated (3 + 3 study design). Primary objectives were to determine the maximum tolerated dose and the recommended dose for future studies and to evaluate safety/tolerability. Secondary and exploratory objectives included pharmacokinetics, immunogenicity, and organ responses on the basis of published consensus criteria. RESULTS: Twenty-seven patients were enrolled in seven cohorts (dose-escalation component). No drug-related serious adverse events (AEs), discontinuations because of drug-related AEs, dose-limiting toxicities, or antidrug antibodies were reported. The most frequent AEs were fatigue, upper respiratory tract infection, cough, and dyspnea. Recommended dosing was 24 mg/kg. Pharmacokinetics support intravenous dosing every 28 days. Of 14 cardiac-evaluable patients, eight (57%) met the criteria for cardiac response and six (43%) had stable disease. Of 15 renal-evaluable patients, nine (60%) met the criteria for renal response and six (40%) had stable disease. CONCLUSION: Monthly infusions of NEOD001 were safe and well tolerated. Recommended future dosing was 24 mg/kg. Organ response rates compared favorably with those reported previously for chemotherapy. A phase II expansion is ongoing. A global phase III study (NCT02312206) has been initiated. Antibody therapy targeting misfolded proteins is a potential new therapy for the management of AL amyloidosis.

Evidence that enzyme processivity mediates differential Aß production by PS1 and PS2.

The γ-secretase complex cleaves the carboxy-terminal 99 residue (C99) fragment of the amyloid precursor protein (APP) to generate the amyloid-ß (Aß) peptide. The catalytic activity of this complex is mediated either by the presenilin- 1 (PS1) or the presenilin-2 (PS2) subunit. In vitro and in vivo studies have demonstrated that PS1-containing complexes generate more total Aß product than PS2-containing complexes, indicating greater cleavage activity by PS1- containing γ-secretase complexes at the APP γ-site. However, it remains untested whether γ-secretase cleavage at the APP -site, which precedes γ-site cleavage and produces the physiologically active APP intracellular domain (AICD), follows the same rule. Using a novel Swedish APP-GVP substrate to facilitate the parallel detection of Aß and AICD products from PS1-/-/PS2-/- cells co-transfected with either PS1 or PS2, we observed that while PS1 generates more total Aß product than PS2, consistent with published reports, PS1 and PS2 unexpectedly generate equal amounts of AICD product. We also observed that PS1 and PS2 produce equivalent amounts of Notch intracellular domain (NICD), indicating equal cleavage activity at the Notch S3-site (the corollary of the APP -site). Our findings suggest that processivity differences between PS1 and PS2 underlie the differential production of Aß peptide. Taken together these findings offer novel insights into γ- secretase biology and have important implications for therapeutically targeting γ-secretase.

Elevated alpha-synuclein impairs innate immune cell function and provides a potential peripheral biomarker for Parkinson's disease.

Alpha-synuclein protein is strongly implicated in the pathogenesis Parkinson's disease. Increased expression of α-synuclein due to genetic multiplication or point mutations leads to early onset disease. While α-synuclein is known to modulate membrane vesicle dynamics, it is not clear if this activity is involved in the pathogenic process or if measurable physiological effects of α-synuclein over-expression or mutation exist in vivo. Macrophages and microglia isolated from BAC α-synuclein transgenic mice, which overexpress α-synuclein under regulation of its own promoter, express α-synuclein and exhibit impaired cytokine release and phagocytosis. These processes were affected in vivo as well, both in peritoneal macrophages and microglia in the CNS. Extending these findings to humans, we found similar results with monocytes and fibroblasts isolated from idiopathic or familial Parkinson's disease patients compared to age-matched controls. In summary, this paper provides 1) a new animal model to measure α-synuclein dysfunction; 2) a cellular system to measure synchronized mobilization of α-synuclein and its functional interactions; 3) observations regarding a potential role for innate immune cell function in the development and progression of Parkinson's disease and other human synucleinopathies; 4) putative peripheral biomarkers to study and track these processes in human subjects. While altered neuronal function is a primary issue in PD, the widespread consequence of abnormal α-synuclein expression in other cell types, including immune cells, could play an important role in the neurodegenerative progression of PD and other synucleinopathies. Moreover, increased α-synuclein and altered phagocytosis may provide a useful biomarker for human PD.

A beta immunotherapy: Lessons learned for potential treatment of Alzheimer's disease.

Amyloid-beta (A beta) immunotherapy for treatment of Alzheimer's disease (AD) was first described in 1999 and has been very informative regarding the role of A beta in AD. Through the efforts of many laboratories we now know that it is possible to reduce amyloid burden and many related AD pathologies in numerous animal models of the disease. Furthermore, initial clinical testing with AN1792, composed of A beta(1-42 )and an adjuvant, has yielded very important insights into both the clinical potential of the approach and the impact of A beta peptide on the disease. A brief review of our current understanding of A beta immunotherapy is described. These findings have led to newer alternative A beta immunotherapy approaches that include both active and passive approaches that are currently in clinical testing in both the USA and Europe.