GRADUATE I AND II: Factors that may influence participant response to subcutaneous gantenerumab

Background GRADUATE I (NCT03444870) and GRADUATE II (NCT03443973) were two Phase III trials that investigated the efficacy and safety of gantenerumab, a subcutaneous fully human monoclonal antibody that binds aggregated forms of amyloid‐beta, in participants with early Alzheimer’s disease (AD). Although the studies did not meet their primary endpoints, participant characteristics that might influence response to gantenerumab were evaluated. Method Eligible participants with early AD (mild cognitive impairment [MCI] due to AD or mild AD dementia) were randomized 1:1 to receive gantenerumab or placebo. Gantenerumab‐treated participants were up‐titrated to 510 mg subcutaneous gantenerumab every 2 weeks. The primary endpoint was change from baseline to Week 116 in Clinical Dementia Rating‐Sum of Boxes (CDR‐SB). Secondary endpoints of cognition (ADAS‐Cog13) and function (ADCS‐ADL, FAQ) were assessed. Pre‐specified and exploratory post‐hoc subgroup analyses on these endpoints were performed. Result Across endpoints, there were consistent trends towards larger point estimates of gantenerumab treatment effect compared with placebo at Week 116 in males (using CDR‐SB as representative example: GRADUATE I: 16% relative reduction (RR); GRADUATE II: 17% RR) vs females (GRADUATE I: 3% RR; GRADUATE II: –2% RR) and participants with MCI (GRADUATE I:15% RR; GRADUATE II:10% RR) vs mild AD (GRADUATE I: 4% RR; GRADUATE II: 2% RR). This pattern was not consistently seen when using CDR‐Global Score (0.5 vs >0.5) to define disease stage. Compliers, defined as participants who received ≥90% of the intended cumulative dose, had an increased point estimate of treatment effect (CDR‐SB: GRADUATE I: 17% RR; GRADUATE II: 18% RR) vs non‐compliers (CDR‐SB: GRADUATE I: –1% RR; GRADUATE II: –3% RR). In a pooled analysis, a larger point estimate of treatment effect vs placebo was observed in East‐Asian vs Non‐East‐Asian countries (CDR‐SB: RR 38% vs 5%). The East‐Asian population had lower baseline weight, greater treatment compliance, and accordingly higher plasma exposure, than the Non‐East‐Asian population, suggesting this observation is not driven by racial differences in treatment response. Conclusion Subgroup analyses in the GRADUATE studies provide insights into participant characteristics that may influence the degree of clinical response to gantenerumab treatment. Higher gantenerumab exposure may result in greater clinical efficacy.