Efficacy and safety of butylphthalide in patients with mild cognitive impairment: a multicentre, randomised, double-blind, placebo-controlled trial (EBMCI study)

Introduction

Alzheimer’s disease (AD) is a neurodegenerative disease with progressive cognitive disorder as the main clinical manifestation. It is widely recognised for its high prevalence, disability rate, economic burden and low rates of seeking medical advice.1 Studies have confirmed that AD is the leading cause of age-related dementia, affecting approximately 41 million people worldwide, according to the Alzheimer’s Disease Association’s World 2021 report.2 In China, the estimated overall prevalence of dementia among the elderly over 60 years old was 6.0% in 2018, with the prevalence of AD at 3.9% and approximately 9.83 million people affected.3 Dementia not only poses risks to personal health and quality of life but also imposes significant medical economic, social burdens and psychological pressure on both the country and the patient’s family. The global social cost of dementia was estimated at US$1.3 trillion in 2019, equivalent to 1.5% of the global gross domestic product and is projected to reach US$2.8 trillion by 2030.4 The total social and economic burden of AD in China amounted to US$167.74 billion and is expected to reach US$254 billion by 2030.5 Additionally, AD ranks as the eighth leading cause of death among the elderly in China.6 Therefore, research into effective AD treatments is crucial for enhancing population health and alleviating economic burden.

Research has indicated that individuals with AD may begin to experience pathological brain changes 15–20 years before the appearance of dementia symptoms.7 Consequently, researchers have recognised the necessity of shifting AD research focus from the dementia phase to the predementia phase.8 Mild cognitive impairment (MCI) refers to the symptomatic predementia phase, characterised by mild memory or cognitive impairment in elderly individuals who have not yet developed dementia, with a prevalence rate of 15.5% among people over 60 years old.3 9 Research has demonstrated that individuals with MCI, even those who have reverted to cognitively normal, are more likely to progress to dementia at an accelerated pace compared with age-matched healthy controls.10 About 15% of MCI patients develop dementia within 2 years11 and around one-third develop dementia within 5 years.12 Consequently, early intervention in the symptomatic predementia phase of AD holds the potential to delay or even reverse cognitive deterioration.

Despite the high prevalence of MCI, there are currently only a limited number of effective therapeutic drugs available. And most drugs do not address the underlying pathology or halt the progression of the disease. Recently, the phase III trial of the anti-Aβ monoclonal antibody drug lecanemab has shown promise in delaying cognitive decline by addressing AD pathogenesis.13 Given the complex nature of AD pathophysiology,14–16 a combined modality therapy using multiple drugs with a single mechanism of action or multitarget drugs could be a promising treatment strategy. Research has suggested that cerebrolysin, a neuroprotective drug, may enhance cognition in moderate to advanced AD patients through a multitarget mechanism.17 However, more research is needed to determine the effectiveness of neuroprotective drugs in the MCI stage.

Previous studies have confirmed that DL-3-n-butylphthalide (NBP), a drug developed independently in China, exhibits a multitarget effect by regulating the expression of Caspase-3, Caspase-9, Bcl-2 and BDNF/TrkB/PI3K/AKT, among others. This drug exerts neuroprotective effects by safeguarding mitochondria, reducing oxidative stress, combating inflammation and decreasing neuronal apoptosis.18–20 Animal studies have shown that NBP soft capsules can effectively improve cholinesterase activity, activate mitochondrial enzyme and enhance mitochondrial function in rats with hypoperfusion dementia, thus improving the memory of AD animal model.21–23 Furthermore, our previous research confirmed the ability of NBP to improve memory function in patients with vascular cognitive impairment without dementia (VCIND) caused by subcortical ischaemic small vessel disease.24 Therefore, we hypothesise that NBP might have a therapeutic effect on MCI and designed this study. Although a previous study has investigated the effect of NBP combined with donepezil in AD, only the synergistic effect of NBP has been confirmed, rather than its own therapeutic effect.25 The objective of this study is to compare the cognitive impairment, activities of daily living (ADL), psychobehavioural symptoms and liver and kidney function in patients with MCI who are treated with NBP versus placebo. The study seeks to evaluate the efficacy and safety of NBP soft capsules in treating MCI and to explore the potential for effective treatment in the early phase of AD.

Methods and analysis

Study design

This is a randomised, double-blind, prospective, multicentric, placebo-controlled, 12-month trial in 270 participants with MCI for evaluation of the efficacy and safety of NBP. The research protocol is written based on the Standard Protocol Items: Recommendations for Interventional Trials 2013 statement.26 Figure 1 as given below is the flow chart for the trial.

Figure 1

Flow chart. ADL, Activities of Daily Living; CDR, Clinical Dementia Rating Scale; FDG-PET, fluoro-D-glucose positron emission tomography; HAMD, Hamilton Depression Scale; MMSE, Mini-Mental State Examination; NPI, neuropsychiatric inventory.

Study setting

This multicentric study is being conducted in 25 investigational sites in China, which are certified high-level clinical facilities in the provision of treatment for cognitive impairment and accept compliance with the standard study protocol. The coordinating centre is located at Xuanwu Hospital of the Capital Medical University. The detail about 25 investigational sites is presented in online supplemental file.

Supplemental material

Participants

Patients meeting the diagnostic criteria for MCI due to AD will be considered for inclusion in this study.27

Reports of cognitive impairment by patients or informants, or identification of impairment by experienced clinicians.
Objective evidence of impairment in one or more cognitive domains, particularly episodic memory dysfunction as indicated by neuropsychological tests.
Mild impairment in complex instrumental daily activities while maintaining independence in basic daily living activities.
Absence of a dementia diagnosis.

Subjects must meet all of the following criteria:

Inpatients or outpatients aged 50–85 years.
Mini-Mental State Examination (MMSE)28 score 20–26 (including 20 and 26), the clinical dementia rating scale (CDR)29 score=0.5.
Be able to communicate in Chinese.
Sign the informed consent.

Patients will be excluded if they have any of the following:

Diagnosed with dementia after baseline investigation.
A clear history of stroke and clear symptoms or signs of neurological deficit at the time of onset, leaving the corresponding responsible lesions on the neuroimaging.
Severe white matter lesions, Fazekas score≥3.
Any cause that may lead to consciousness disorder.
Participants who are unable to complete the neuropsychological examination due to severe aphasia or physical disability.
Currently suffering from related depression (Hamilton Depression Scale score, HAMD>8) or mental illness.
A history of alcoholism, or drug addiction, or brain trauma, epilepsy, encephalitis, normal intracranial pressure hydrocephalus and other neurological diseases that can cause cognitive impairment.
Systemic diseases that may lead to MCI (eg, liver and kidney insufficiency, endocrine disorders, vitamin deficiency).
Celery allergy.
Participating in other drug clinical investigations.

Recruitment and randomisation

Recruitment began in November 2018, and the trial was planned to last until the end of May 2024. Prior to the survey, written informed consent will be obtained from all participants or their caregivers. Patients who meet the inclusion criteria based on MMSE, CDR, HAMD and brain MRI performed before enrolment are selected. Subsequently, all participants selected will be randomised in a 1:1 ratio to receive either NBP or placebo in masked interventions using SAS V.9.4 (SAS Institute). In order to preserve blinding, the randomisation procedure and drug dispensing are performed by a blinded statistician and a researcher, who are not related to the study. A randomisation list stratified by centre, is saved to the chief investigator and China Shijiazhuang Pharmaceutical Group. Both the chief investigator and pharmaceutical group should also remain blinded throughout the study, except in emergency situations.

This is a double-blind study in which patients and site personnel will be blinded to therapy. Every investigation site will be supplied with kits of study drug labelled with sequential numbers corresponding to the randomisation number. When randomised, each successive participant is assigned to the lowest numbered kit in sequence at each site by the site investigator.

At the end of the study, after the database is locked and subject populations have been determined, treatment assignments will be unblinded. The blind for an individual subject should not be broken during conduct of the study except in the case of a medical situation for which it is deemed essential to know which treatment the subject has received in order to provide appropriate care. In case of emergency, the principal investigator will decide whether to break the blindness and inform the clinical physician of the unblinding result for emergency treatment. If a subject becomes unblinded, the researchers should record the cause and time of unblinding and the subject will be discontinued from the study. After unblinding, all efficacy data will be excluded from the analysis, but adverse events (AEs) will still be included in the statistics.

Interventions

The trial drugs and placebos are produced and provided by China Shijiazhuang Pharmaceutical Group, stored at the investigation site following the drug storage requirements. A total of 270 subjects are randomly assigned to receive either NBP soft capsules or equivalent dose of an identical-looking placebo to maintain blinding. Based on previous studies,24 30 31 a dose of 200 mg of NBP (ie, two soft capsules) will be taken orally, three times per day for 12 months. The control is a matched placebo. The placebo is identical to the intervention but contains no NBP. Additionally, the use of cholinesterase inhibitors, memantine, cetam or ginkgo biloba preparations, known to enhance cognitive function, is strictly prohibited.

Assessments

Experimental procedures

The experimental procedures consist of three main stages: screening, baseline and follow-up. During the screening period (visit 0), participants will provide written informed consent and undergo assessments for demographic data, neuropsychology scales (MMSE, CDR, HAMD) and brain MRI. Well-trained researchers will collect this data, which will then be reviewed by investigators to determine eligibility. The baseline visit (visit 1), occurring within 8 weeks after screening, will be conducted to record various data including demographics, allergic and medical history, concomitant diseases, medications, laboratory tests, fluoro-D-glucose positron emission tomography (FDG-PET) and neuropsychology. Repeat collection for MMSE, CDR, HAMD and brain MRI is not required at baseline. The follow-up period involves interviews with participants for 12 months, with visits scheduled at 3, 6, 9 and 12 months (visits 2–5) after baseline (visit 1). Efficacy assessments, including Alzheimer’s Disease Assessment Scale-Cognitive Subscale (ADAS-cog) and other neuropsychology scales, will be repeated at 6 and 12 months during treatment while MMSE, neuropsychiatric inventory (NPI) and ADL will be followed up every 3 months. And FDG-PET will be used for assessment at the end of the trial. Safety assessments, including vital sign measurements, specialised nervous system examinations, AEs recording, combined medication records, will be conducted at each follow-up visit and laboratory tests will be performed every 6 months. The data collection schedule is presented in table 1.

View this table:

Table 1

Schedule of data collection

Laboratory tests

Blood samples will be collected by trained medical staff according to a uniform standard and sent to a designated testing centre. Venous blood specimens are drawn into two separate vacuum tubes after an overnight fast, with one vacuum tube (4 mL) filled with coagulant and another one (6 mL) with EDTA. The blood testing indicators include fasting blood glucose, blood lipids, myocardial enzymes, liver and kidney function, mainly used for safety assessments.

Neuropsychology assessments

The neuropsychological assessments will be conducted, including the Chinese version of the 12-item ADAS-cog₁₂,32 MMSE, CDR, NPI,33 ADL,34 Immediate Recall and Delay Recall of WHO-University of California Los Angeles Auditory Verbal Learning Test (WHO-UCLA AVLT),35 Trail Making Test (TMT) and36 Digit Span.37 The ADAS-cog₁₂ assesses memory, language, orientation, reasoning, praxis and concentration, with a total score range of 0–75 (higher scores indicate greater cognitive impairment). Other assessments include MMSE for cognitive function screening (score range 0–30, lower scores indicate greater impairment), the CDR sum of the boxes (CDR-SB) for dementia severity (score range 0–18, higher scores indicate better function), the Chinese version of the ADL scale for daily living ability (score range 20–80, higher scores indicate greater functional impairment), NPI for behaviour and autonomic nervous system assessment (score range 0–144, higher scores indicate greater impairment), WHO-UCLA AVLT for immediate and delayed recall, TMT A for visual search and motor speed, TMT B for Executive function (including cognitive flexibility, attention distraction and working memory) and Digit Span for working memory performance (score range 0–10 for Digit Span Forward and 0–8 for Digit Span Backward).

Neuroimaging assessments

A quantitative method will be employed to analyse the brain FDG-PET image data. This methodology will entail registering the FDG-PET image (radiology count value) to the standard space using an image registration algorithm, and automatically registering FDG-PET image into brain regions corresponding to the MRI partition. The grey value of each voxel will be divided by the average voxel grey value of the individual cerebellum, and the relative brightness information in each brain region will be assessed to calculate the mean and variance of each brain region’s standardised uptake values ratio (SUVR).

Medication compliance assessment

Medication compliance is assessed by counting the number of unused capsules remaining in the medicine bottle. The protocol specifies that medication compliance should fall within the range of 80%–120%, with anything outside of this range considered a protocol violation. Medication compliance is calculated using the following formula:

Discontinuations management

Participants have the option to withdraw from the study at any time for various reasons. Instances of participant drop-out should be promptly reported to the PI, with details of the timing and reasons document. In cases where participants drop-out, efforts should be made to maintain the integrity of the data and ensure proper storage.

The reasons for discontinuation of the trial are defined as follows:

Any end oint event occurs, including new cerebral infarction, cerebral haemorrhage, myocardial infarction, organ failure and death from all causes.
Curative effect is not satisfied.
Acute attack or aggravation of organic diseases during the observation period.
Intolerable adverse drug reactions (ADRs).
Subjects’ requirements: voluntary withdrawal, resident relocation, schedule conflict.
Protocol violation: violation of the main content of the protocol, such as medication compliance lower than 80% or higher than 120%, especially when it is related to the safety of the subject.
Loss of follow-up: repeatedly failed to contact according to the conventional contact method, and the follow-up time exceeded the window period by 2 months.
Other possible reasons.

AEs management

AEs are defined as all unexpected and adverse medical events that occurred in the study, regardless of whether they are related to drugs. Serious AEs are defined as (1) lethal, (2) life-threatening, (3) causing hospitalisation or prolonging hospitalisation time, (4) causing permanent or serious disability and (5) resulting in congenital malformations or birth defects. ADRs are defined as adverse reactions that occur during the normal application of drugs at prescribed doses and are not expected to be causally related to the drug use. To assess the relationship between AEs and the study drug, the following terminologies are defined:

The time of occurrence of AEs coincided with the time of administration.
AEs are consistent with the known adverse reaction of the drug.
AEs cannot be explained by combining medication or other reasons.
AEs disappeared after drug withdrawal.
The same adverse reaction occurred after taking the drug again.

According to the above principles, causality can be categorised into five levels: positive related, probable related, possible related, possible unrelated and positive unrelated:

Positive related: both conform to 1–5.
Probable related: both conform to 1–4.
Possible related: both conform to 1–2.
Possible unrelated: conform to 1.
Positive unrelated: All symptoms can be explained by other reasons and do not meet all the above criteria.

In the cases of any AEs, whether related to the drug being tested or not, the investigator must promptly administer appropriate treatment. For all AEs, the investigator must pursue and obtain information adequate to determine the reason and outcome of the AEs.

Outcomes

The primary efficacy endpoint of this study is ADAS-cog.32

The secondary efficacy outcomes include the MMSE, CDR, ADL, NPI, Immediate Recall, Delay Recall, TMT and Stroop Interference Test, Forward Digit Span, Backward Digit Span Test, SUVR of FDG-PET.

Safety measures include AEs, physical examinations (vital signs and specialised examination of the nervous system), laboratory tests (liver and kidney function, myocardial enzymes, fasting blood glucose, blood lipids).

Data management

The data management of this study complies with the requirements of good clinical practice (GCP). The data are monitored by Beijing Igus Pharmaceutical Technology Development, and the database structure is confirmed by the data management department of the researcher. After the blind audit, lock the SAS database and then break the blind.

Statistical analysis

Data from the full-analysis set (FAS) and per-protocol set (PPS) will be analysed using SAS V.9.4 (SAS Institute). The FAS population includes all randomised patients who receive at least one follow-up record after treatment and a complete baseline assessment. The PPS population consists of patients who complete the 12-month treatment and evaluation without major protocol violations. Cases that withdraw early due to invalidity are also included in the PPS and treated as invalid cases. Statistical tests will be two sided, with p<0.05 considered statistically significant. Categorical data will be presented as numbers and per cent while continuous data will be as mean and SD or median, quartile, minimum and maximum, as appropriate. Demographic and clinical characteristics will be compared at baseline with t-test or Wilcoxon rank-sum test for continuous variables and with Cochran-Mantel-Haenszel test for categorical variables. If baseline values are not available, values from the screening period will be used. Missing efficacy indicator data will be replaced with the last observation carried forward method.

In the therapeutic efficacy analysis, an analysis of covariance mode is used to compare changes in primary and secondary efficacy indicator scores from baseline between the NBP group and the placebo group. NBP treatment is considered as a fixed effect, with potential covariates such as baseline scores and research centres being corrected for. Additionally, the interaction between drug therapy and research centre is also evaluated.

Safety will be assessed by summarising AEs. The changes are analysed statistically before and after treatment, and the differences of AEs frequency by χ² test or exact probability test.

Sample size

The power of this study will be calculated based on the primary endpoint, change from baseline on ADAS-cog. The primary endpoint data are estimated using a dominance test comparing two means (superiority threshold D=1.5). A one-sided test is used with a statistical significance level of 0.025 and a power of 80%. Based on the experience of epidemiologists in the field, assuming an expected 3.3-point drug-placebo mean difference in change from baseline on the ADAS-cog, with an SD of 4.7, the calculated sample size for each group is 108. Accounting for a 20% drop-out rate, the total number of patients to be randomised is set to 270.

Data and safety monitoring

This test will be carried out in accordance with the Declaration of Helsinki (2013) and GCP principles. Researchers must read the research protocol completely and strictly follow its regulations. Standard operating procedures will be adhered to for all activities relevant to the quality of the study, including protocol compliance, data collection, quality control, and data analyses and reporting. The project management and monitoring of this study is undertaken by data monitoring and security committee.

Patient and public involvement

Patients and/or the public are not involved in the design, or conduct, or reporting, or dissemination plans of this research.

Ethics and dissemination

Research ethics approval

The study involving human participants has been approved by Ethics Committee of Xuan Wu Hospital (No. 2017058). The participants will provide their written informed consent to participate in this study. Results will be published in peer-reviewed medical journals and disseminated to healthcare professionals at local and international conferences.

Protocol amendments

In clinical trials, if any shortcomings in the protocol due to poor consideration that are detrimental to the interests of the subject, the quality or progress of the clinical trial are found, necessary amendments will be made. Revisions to the protocol may be organised by the lead agency and the clinical trial responsible unit, with corresponding amendments to the informed consent. The amended protocol and informed consent must be reported to the lead agency and approved by the Ethics Committee before it can be used in clinical trials.

Informed consent

The investigator must explain the item, purpose, relevant operation and expected course of treatment in this clinical trial to the subject (or his legal agent). Each patient enrolled in this trial must sign the informed consent.

Data sharing

All relevant data will be safely stored in the principal investigator unit within the period of archive preservation required by law. The project data sets will be stored in the study database, and all data sets will be password protected. According to the data-sharing protocol of the research centre, anonymous data can be published within 6 months after the completion of the trial. Further inquiries about certain articles can be directed to the corresponding authors.

Discussion

The efficacy of the multitarget neuroprotective drug NBP in improving the cognition functioning of patients with VCIND has been previously confirmed, and it has been found that receiving three times daily oral NBP 200 mg for 24 weeks is safe.24 Multiple animal studies have indicated that NBP soft capsules can enhance the memory in AD animal model by improving cholinesterase activity, activating mitochondrial enzymes and boosting mitochondrial function in rats with hypoperfusion dementia.21–23 However, there is a lack of clinical studies on the therapeutic effects of NBP in MCI. Large-scale, multicentre, randomised and double-blind study is necessary to validate its effectiveness. This study is the first randomised controlled trial to assess the efficacy and safety of NBP in patients with MCI. Currently, the choice of therapeutic drugs for MCI is very limited due to the failure of clinical trials or adverse effects. Repurposing existing drugs and using multitarget treatments may show promising strategies for the early phase of AD therapy.

The target population is the main advantage of this study. The pathological process of dementia begins many years before clinical diagnosis,7 and the conversion of MCI is highly heterogeneous.11 Therefore, MCI is the earliest and potentially the most suitable stage for introducing antidementia drugs. The methods and results of this study can offer valuable insights into criteria for selecting individuals with MCI, outcome measurements and sample size considerations. Moreover, by integrating neuroimaging tests for population selection and effectiveness assessment, the study provides valuable insights into criteria for participant selection, outcome measurements. Unlike traditional methods that mainly rely on subjective indicators like medical history, cognition situation and informed reporting, this study confirms MCI by excluding a history of stroke and severe white matter lesions using MRI, to control the heterogeneity of enrolled subjects. Additionally, FDG-PET is used to detect early slight changes in MCI and assess efficacy.

There is a limitation in this study. This trial is designed in a specific AD-derived MCI population. So, the results may not be generalisable to other stages of cognitive impairment.

In summary, the EBMCI study aims to provide high-quality evidence on whether early use of multitarget neuroprotection drug NBP can enhance cognitive function in individuals with MCI. This trial will offer valuable insights into the potential for effective drug interventions at an early stage of this disease.

This post was originally published on https://bmjopen.bmj.com