At-Home Administration of Gantenerumab by Care Partners to People with Early Alzheimer's Disease: Feasibility, Safety and Pharmacodynamic Impact

BACKGROUND

Monoclonal antibodies that target amyloid-beta and remove amyloid plaques can slow cognitive and functional decline in early Alzheimer's disease. Gantenerumab is a subcutaneously administered fully-human anti-amyloid-beta monoclonal antibody with highest affinity for aggregated amyloid-beta. Since the phase 3 GRADUATE trials did not meet the primary endpoint (change from baseline to Week 116 in Clinical Dementia Rating scale - Sum of Boxes), development of gantenerumab in sporadic Alzheimer's disease was stopped and all ongoing trials were terminated early due to sponsor decision. Subcutaneous administration at the clinic or at home by care partner would be an important option for other therapies in this class in order to increase flexibility and reduce overall burden. The insights obtained from the experience with gantenerumab home administration by care partner in the phase 2 GRADUATION trial will serve to guide the ongoing efforts with other anti-amyloid-beta antibodies.

OBJECTIVES

To evaluate the pharmacodynamic effects on brain amyloid load of once weekly subcutaneous administration of gantenerumab and the safety and feasibility of home administration by care partners.

DESIGN

Phase 2, open-label, single arm study.

SETTING

Multicenter trial conducted in 33 sites in 8 countries from November 2020 to March 2023.

PARTICIPANTS

Participants aged 50 to 90 with early symptomatic Alzheimer's disease (mild cognitive impairment/mild dementia due to Alzheimer's disease), and evidence of amyloid positron emission tomography positivity.

INTERVENTION

Participants could receive up to 255 mg gantenerumab once-weekly, administered subcutaneously at site or at home by healthcare professionals or non-healthcare-professional care partners.

MEASUREMENTS

The primary endpoint was the change from baseline to Week 52 and to Week 104 in brain amyloid load as measured by PET centiloid levels. The secondary endpoints were responses to the home administration questionnaire, plasma concentrations and safety.

RESULTS

The overall number of participants enrolled was 192, with a mean (standard deviation) amyloid PET load at baseline of 101.80 (29.80) centiloids. At the time of early study termination by sponsor, 149 participants had valid Week 52 amyloid PET data (primary endpoint), and 12 participants had an early termination PET within the pre-defined time range of Week 104. The mean change in amyloid PET from baseline to Week 52 and Week 104 was -26.19 centiloids (range: -75.6-15.8; n=149) and -35.48 centiloids (range: -63.2--7.0; n=12), respectively. Responses to the home administration questionnaire at Week 52 (n=148) indicated that the majority of care partners (88-97%) considered administration of study drug at home easy (30.4%) or very easy (57.4%), and convenient (25.7%) or very convenient (70.9%). Care partners felt confident (31.1%) or very confident (62.2%) and satisfied (29.7%) or very satisfied (64.9%) with giving the injection at home. Responses by care partners at Week 36 (n=72), Week 76 (n=126) and Week 104 (n=29) and participant (patient) assessment of convenience and satisfaction at these time points were similar. There were no new safety findings associated with gantenerumab administered subcutaneously once weekly at 255 mg or safety issues associated with at-home injections by non-healthcare professional care partners.

CONCLUSIONS

Once-weekly subcutaneous home administration of the anti-amyloid-beta antibody gantenerumab by non-healthcare-professional care partners to participants with early Alzheimer's disease was feasible, safe, well tolerated, and considered as a convenient option by both the care partners and participants with Alzheimer's disease. Although gantenerumab's development has been stopped due to lack of efficacy, this approach has the potential to reduce the frequency of hospital/outpatient clinic visits required for treatment with other anti-amyloid-β antibodies and can increase flexibility of drug administration for people living with Alzheimer's disease and their families.

Establishing Clinically Meaningful Change on Outcome Assessments Frequently Used in Trials of Mild Cognitive Impairment Due to Alzheimer's Disease

BACKGROUND

Consensus is lacking on what constitutes a meaningful score change for individual patients on clinical outcome assessments (COAs) that are commonly used in clinical trials of Alzheimer's disease. Such thresholds are one important approach to help contextualize trial results and demonstrate meaningful treatment benefit.

OBJECTIVES

To estimate meaningful within-patient change thresholds for the Clinical Dementia Rating Scale - Sum of Boxes (CDR-SB), Alzheimer's Disease Assessment Scale - Cognitive Subscale (ADAS-Cog), and the Mini-Mental State Examination (MMSE) among participants with mild cognitive impairment (MCI).

DESIGN

Retrospective anchor- and distribution-based analyses of data from the ADC-008 (NCT00000173) study were used to estimate thresholds for meaningful within-patient change on the target measures.

SETTING

Analyses were conducted using data from ADC-008 a Phase III, multicenter, randomized, double-blind, placebo-controlled, parallel-group study among participants with the amnestic subtype of MCI, which was conducted by the Alzheimer's Disease Cooperative Study (ADCS) between March 1999 and January 2004 in the United States and Canada.

PARTICIPANTS

Analyses were based on 769 eligible participants who completed the baseline assessment from 69 ADCS sites in the United States and Canada.

MEASUREMENTS

The target outcome measures for this analysis included the CDR-SB, the ADAS-Cog, and the MMSE. The anchor measures for this analysis included the Global Deterioration Scale and the MCI-Clinical Global Impression of Change.

RESULTS

Focusing on the 12-month time point, within-patient increases of 1-2.5 points in the CDR-SB and increases of 2-5 points on the 11-item ADAS-Cog and 13-item ADAS-Cog, on average, reflect minimal-to-moderate levels of deterioration, respectively.

CONCLUSIONS

These thresholds may be useful to aid the interpretation of Alzheimer's disease clinical trial data by illustrating meaningful within-patient progression over the course of a clinical trial via supplementary progressor analyses, which may in turn be informative for treatment decisions. Estimates generated via these methods are specifically intended to evaluate within-patient change and are not intended to assess the magnitude and meaningfulness of differences between group-level changes over time.

Psychometric Properties of the Clinical Dementia Rating - Sum of Boxes and Other Cognitive and Functional Outcomes in a Prodromal Alzheimer's Disease Population

BACKGROUND

The Clinical Dementia Rating-Sum of Boxes (CDR-SB) has been proposed as a primary outcome for use in prodromal AD trials. However, the psychometric properties of this, and of other commonly used measures, have not been well-established in this patient population.

OBJECTIVE

To describe the psychometric properties of commonly used efficacy measures in a clinical trial of prodromal AD.

SETTING

Data were gathered as part of a two-year clinical trial.

PARTICIPANTS

Patients had biomarker confirmed prodromal AD.

MEASUREMENTS

Clinical Dementia Rating (CDR), Functional Activities Questionnaire (FAQ), Alzheimer's Disease Assessment Scale - Cognition Subscale 11 and 13 (ADAS-Cog), Mini Mental State Exam (MMSE), and Free and Cued Selective Reminding Test (FCSRT-IR [words]). Assessments were conducted at least every 24 weeks.

RESULTS

For the CDR-SB, test-retest reliability was good (intra-class correlation coefficient [ICC]=0.83); internal consistency was 0.65 at baseline but above 0.8 at later assessments. Relationships between the CDR-SB and other measures were as expected (higher correlations with more closely related constructs), and the CDR-SB differentiated between patients with different severities of dementia (-2.9 points difference between CDR-Global Score 0.5 and 1, P<.0001). Floor and ceiling effects on the CDR-SB total score were minimal; however, at baseline there were ceiling effects in the personal care domain. Further detail is provided on the psychometric properties of ADAS-Cog, MMSE, FCSRT-IR and FAQ in this population.

CONCLUSION

The psychometric properties of the CDR-SB are adequate in prodromal AD and continued use is warranted in clinical trials. However, there remains scope for improvement in the assessment of functional constructs and development of novel measures should continue.