Gantenerumab: an anti-amyloid monoclonal antibody with potential disease-modifying effects in early Alzheimer's disease.

BACKGROUND: This review describes the research and development process of gantenerumab, a fully human anti-amyloid monoclonal antibody in development to treat early symptomatic and asymptomatic Alzheimer's disease (AD). Anti-amyloid monoclonal antibodies can substantially reverse amyloid plaque pathology and may modify the course of the disease by slowing or stopping its clinical progression. Several molecules targeting amyloid have failed in clinical development due to drug-related factors (e.g., treatment-limiting adverse events, low potency, poor brain penetration), study design/methodological issues (e.g., disease stage, lack of AD pathology confirmation), and other factors. The US Food and Drug Administration's approval of aducanumab, an anti-amyloid monoclonal antibody as the first potential disease-modifying therapy for AD, signaled the value of more than 20 years of drug development, adding to the available therapies the first nominal success since cholinesterase inhibitors and memantine were approved. BODY: Here, we review over 2 decades of gantenerumab development in the context of scientific discoveries in the broader AD field. Key learnings from the field were incorporated into the gantenerumab phase 3 program, including confirmed amyloid positivity as an entry criterion, an enriched clinical trial population to ensure measurable clinical decline, data-driven exposure-response models to inform a safe and efficacious dosing regimen, and the use of several blood-based biomarkers. Subcutaneous formulation for more pragmatic implementation was prioritized as a key feature from the beginning of the gantenerumab development program. CONCLUSION: The results from the gantenerumab phase 3 programs are expected by the end of 2022 and will add critical information to the collective knowledge on the search for effective AD treatments.

A phase 3 trial of semagacestat for treatment of Alzheimer's disease.

BACKGROUND: Alzheimer's disease is characterized by the presence of cortical amyloid-beta (Aß) protein plaques, which result from the sequential action of ß-secretase and γ-secretase on amyloid precursor protein. Semagacestat is a small-molecule γ-secretase inhibitor that was developed as a potential treatment for Alzheimer's disease. METHODS: We conducted a double-blind, placebo-controlled trial in which 1537 patients with probable Alzheimer's disease underwent randomization to receive 100 mg of semagacestat, 140 mg of semagacestat, or placebo daily. Changes in cognition from baseline to week 76 were assessed with the use of the cognitive subscale of the Alzheimer's Disease Assessment Scale for cognition (ADAS-cog), on which scores range from 0 to 70 and higher scores indicate greater cognitive impairment, and changes in functioning were assessed with the Alzheimer's Disease Cooperative Study-Activities of Daily Living (ADCS-ADL) scale, on which scores range from 0 to 78 and higher scores indicate better functioning. A mixed-model repeated-measures analysis was used. RESULTS: The trial was terminated before completion on the basis of a recommendation by the data and safety monitoring board. At termination, there were 189 patients in the group receiving placebo, 153 patients in the group receiving 100 mg of semagacestat, and 121 patients in the group receiving 140 mg of semagacestat. The ADAS-cog scores worsened in all three groups (mean change, 6.4 points in the placebo group, 7.5 points in the group receiving 100 mg of the study drug, and 7.8 points in the group receiving 140 mg; P=0.15 and P=0.07, respectively, for the comparison with placebo). The ADCS-ADL scores also worsened in all groups (mean change at week 76, -9.0 points in the placebo group, -10.5 points in the 100-mg group, and -12.6 points in the 140-mg group; P=0.14 and P<0.001, respectively, for the comparison with placebo). Patients treated with semagacestat lost more weight and had more skin cancers and infections, treatment discontinuations due to adverse events, and serious adverse events (P<0.001 for all comparisons with placebo). Laboratory abnormalities included reduced levels of lymphocytes, T cells, immunoglobulins, albumin, total protein, and uric acid and elevated levels of eosinophils, monocytes, and cholesterol; the urine pH was also elevated. CONCLUSIONS: As compared with placebo, semagacestat did not improve cognitive status, and patients receiving the higher dose had significant worsening of functional ability. Semagacestat was associated with more adverse events, including skin cancers and infections. (Funded by Eli Lilly; ClinicalTrials.gov number, NCT00594568.)

Genome-wide scan for copy number variation association with age at onset of Alzheimer's disease.

Alzheimer's disease (AD) is a progressive neurodegenerative disease with high prevalence, which imposes a substantial public health problem. The heritability of AD is estimated at 60-80% forecasting the potential use of genetic biomarkers for risk stratification in the future. Several large scale genome-wide association studies using high frequency variants identified 10 loci accountable for only a fraction of the estimated heritability. To find the missing heritability, systematic assessment of various mutational mechanisms needs to be performed. This copy number variation (CNV) genome-wide association study with age at onset (AAO) of AD identified 5 CNV regions that may contribute to the heritability of AAO of AD. Two CNV events are intragenic causing a deletion in CPNE4. In addition, to further study the mutational load at the 10 known susceptibility loci, CNVs overlapping with these loci were also catalogued. We identified rare small events overlapping CR1 and BIN1 in AD and normal controls with opposite CNV dosage. The CR1 events are consistent with previous reports. Larger scale studies with deeper genotyping specifically addressing CNV are needed to evaluate the significance of these findings.

Identifying amnestic mild cognitive impairment in primary care: a feasibility study.

BACKGROUND AND OBJECTIVE: Amnestic mild cognitive impairment (aMCI), characterized by episodic memory impairment in the absence of clinical dementia, often represents a transitional stage between normal aging and Alzheimer's disease (AD). It is not known if non-expert primary-care physicians (PCPs) can differentiate individuals with no cognitive impairment (NCI), aMCI and mild AD in a primary-care practice setting. This study develops an approach to this question, which is necessary for aMCI to become a treatment target. METHODS: Fourteen experts assessed subjects with memory complaints in terms of their laboratory test results, magnetic resonance imaging findings and scores on the Mini-Mental State Examination, adapted Clinical Dementia Rating Scale and Alzheimer's Disease Assessment Scale-cognitive subscale Delayed Word Recall before designating each subject as having NCI, aMCI or AD. Subjects agreed upon by a consensus committee were assigned to non-expert PCPs who, following brief training, assessed them using the same clinical information and utilizing the same assessment instruments. The chance-corrected inter-rater reliability (expert versus non-expert) measure κ, based on binary outcome (aMCI/not-aMCI), was estimated. RESULTS: The study recruited 119 evaluable subjects (50 aMCI, 27 mild AD and 42 NCI) and demonstrated fair to moderate agreement (κ = 0.423) between experts and non-experts in designation of aMCI. The percent agreement was 72.3%, sensitivity 62.0% and specificity 79.7%. Overall, non-experts under-rated the level of impairment compared with experts. CONCLUSION: This study established the feasibility of making the aMCI designation in the community and identified some likely sources of error. The results suggest that when drugs with clear benefit for aMCI patients are developed, community-based PCPs, with additional, more optimized training, will be able to accurately identify those patients who should receive treatment.