Genome-wide association study of abnormal elevation of ALT in patients exposed to atabecestat.

BACKGROUND: Atabecestat, a potent brain penetrable BACE1 inhibitor that reduces CSF amyloid beta (Aß), was developed as an oral treatment for Alzheimer's disease (AD). Elevated liver enzyme adverse events were reported in three studies although only one case met Hy's law criteria to predict serious hepatotoxicity. METHOD: We performed a case-control genome-wide association study (GWAS) to identify genetic risk variants associated with liver enzyme elevation using 42 cases with alanine transaminase (ALT) above three times the upper limit of normal (ULN) and 141 controls below ULN. Additionally, we performed a GWAS using continuous maximal ALT/ULN (expressed as times the ULN) upon exposure to atabecestat as the outcome measure (n = 285). RESULTS: No variant passed the genome-wide significance threshold (p = 5 × 10- 8) in the case-control GWAS. We identified suggestive association signals in genes (NLRP1, SCIMP, and C1QBP) implicated in the inflammatory processes. Among the genes implicated by position mapping using variants suggestively associated (p < 1 × 10- 5) with ALT elevation case-control status, gene sets involved in innate immune response (adjusted p-value = 0.05) and regulation of cytokine production (adjusted p-value = 0.04) were enriched. One genomic region in the intronic region of GABRG3 passed the genome-wide significance threshold in the continuous max(ALT/ULN) GWAS, and this variant was nominally associated with ALT elevation case status (p = 0.009). CONCLUSION: The suggestive GWAS signals in the case-control GWAS analysis suggest the potential role of inflammation in atabecestat-induced liver enzyme elevation.

Long-term safety and tolerability of atabecestat (JNJ-54861911), an oral BACE1 inhibitor, in early Alzheimer's disease spectrum patients: a randomized, double-blind, placebo-controlled study and a two-period extension study.

BACKGROUND: Atabecestat, a potent brain-penetrable inhibitor of BACE1 activity that reduces CSF amyloid beta (Aß), was developed for oral treatment for Alzheimer's disease (AD). The long-term safety and effect of atabecestat on cognitive performance in participants with predementia AD in two phase 2 studies were assessed. METHODS: In the placebo-controlled double-blind parent ALZ2002 study, participants aged 50 to 85 years were randomized (1:1:1) to placebo or atabecestat 10 or 50 mg once daily (later reduced to 5 and 25 mg) for 6 months. Participants entered ALZ2004, a 12-month treatment extension with placebo or atabecestat 10 or 25 mg, followed by an open-label phase. Safety, changes in CSF biomarker levels, brain volume, and effects on cognitive performance were assessed. RESULTS: Of 114 participants randomized in ALZ2002, 99 (87%) completed, 90 entered the ALZ2004 double-blind phase, and 77 progressed to the open-label phase. CSF Aß fragments and sAPPß were reduced dose-proportionately. Decreases in whole brain and hippocampal volumes were greater in participants with mild cognitive impairment (MCI) due to AD than in preclinical AD, but were not affected by treatment. In ALZ2004, change from baseline in RBANS trended toward worse scores for atabecestat versus placebo. Elevated liver enzyme adverse events reported in 12 participants on atabecestat resulted in dosage modification and increased frequency of safety monitoring. Treatment discontinuation normalized ALT or AST in all except one with pretreatment elevation, which remained mildly elevated. No case met ALT/AST > 3× ULN and total bilirubin > 2× ULN (Hy's law). CONCLUSION: Atabecestat was associated with trend toward declines in cognition, and elevation of liver enzymes. TRIAL REGISTRATION: ALZ2002: ClinicalTrials.gov, NCT02260674, registered October 9, 2014; ALZ2004: ClinicalTrials.gov, NCT02406027, registered April 1, 2015.

BACE inhibitors in clinical development for the treatment of Alzheimer's disease.

INTRODUCTION: The amyloid hypothesis of Alzheimer's disease (AD) affirms that brain accumulation of amyloid-ß (Aß) oligomers and soluble aggregates represent the major pathological event of the disease. Several anti-Aß small organic molecules, monoclonal antibodies and antigens were developed to interfere with Aß production and clearance, including ß-site amyloid precursor protein cleaving enzyme (BACE) inhibitors, blocking the first enzymatic step of Aß formation. All these approaches, including BACE inhibitors, have failed in large randomized clinical trials (RCTs) in mild-to-moderate AD, but further studies are now being carried out in patients at early AD stages and in asymptomatic subjects at risk of developing AD. Areas covered: The paper provides a comprehensive review of BACE inhibitors for AD treatment, focusing on the most advanced compounds in Phase III RCTs. Expert commentary: BACE inhibitors inhibited robustly, and dose-dependently, Aß formation in cerebrospinal fluid of AD patients, but without cognitive, clinical, or functional benefit in large RCTs. BACE inhibition may be not sufficient to decrease brain Aß plaques and aggregates. Indeed, several BACE inhibitors were found to be poorly tolerated and some of them failed also in patients with prodromal AD. This may indicate that blocking the formation of nascent Aß is not useful in AD.

Pharmacodynamics of atabecestat (JNJ-54861911), an oral BACE1 inhibitor in patients with early Alzheimer's disease: randomized, double-blind, placebo-controlled study.

BACKGROUND: ß-Secretase enzyme (BACE) inhibition has been proposed as a priority treatment mechanism for Alzheimer's disease (AD), but treatment initiation may need to be very early. We present proof of mechanism of atabecestat (also known as JNJ-54861911), an oral BACE inhibitor for the treatment of AD, in Caucasian and Japanese populations with early AD who do not show signs of dementia. METHODS: In two similarly designed phase I studies, a sample of amyloid-positive elderly patients comprising 45 Caucasian patients with early AD diagnosed as preclinical AD (n = 15, Clinical Dementia Rating [CDR] = 0) or with mild cognitive impairment due to AD (n = 30, CDR = 0.5) and 18 Japanese patients diagnosed as preclinical AD (CDR-J = 0) were randomized 1:1:1 to atabecestat 10 or 50 mg or placebo (n = 6-8/treatment) daily for 4 weeks. Safety, pharmacokinetics (PK), and pharmacodynamics (PD) (i.e., reduction of cerebrospinal fluid [CSF] amyloid beta 1-40 [Aß1-40] levels [primary endpoint] and effect on other AD biomarkers) of atabecestat were evaluated. RESULTS: In both populations, atabecestat was well tolerated and characterized by linear PK and high central nervous system penetrance of unbound drug. Atabecestat significantly reduced CSF Aß1-40 levels from baseline at day 28 in both the 10-mg (67-68%) and 50-mg (87-90%) dose groups compared with placebo. For Caucasians with early AD, the least squares mean differences (95% CI) were - 69.37 (- 72.25; - 61.50) and - 92.74 (- 100.08; - 85.39), and for Japanese with preclinical AD, they were - 62.48 (- 78.32; - 46.64) and - 80.81 (- 96.13; - 65.49), respectively. PK/PD model simulations confirmed that once-daily 10 mg and 50 mg atabecestat can attain 60-70% and 90% Aß1-40 reductions, respectively. The trend of the reduction was similar across the Aß1-37, Aß1-38, and Aß1-42 fragments in both atabecestat dose groups, consistent with Aß1-40. CSF amyloid precursor protein fragment (sAPPß) levels declined from baseline, regardless of patient population, whereas CSF sAPPα levels increased compared with placebo. There were no relevant changes in either CSF total tau or phosphorylated tau 181P over a 4-week treatment period. CONCLUSIONS: JNJ-54861911 at 10 and 50 mg daily doses after 4 weeks resulted in mean CSF Aß1-40 reductions of 67% and up to 90% in both Caucasian and Japanese patients with early stage AD, confirming results in healthy elderly adults. TRIAL REGISTRATION: ALZ1005: ClinicalTrials.gov, NCT01978548. Registered on 7 November 2013. ALZ1008: ClinicalTrials.gov, NCT02360657. Registered on 10 February 2015.