Efavirenz for Patients With Mild Cognitive Impairment

1.0 BACKGROUND

1.1. Introduction

The brain is the most cholesterol-rich organ in the body. Circulating peripheral cholesterol
cannot cross the blood-brain barrier and enter the brain, so all of cerebral cholesterol is
synthesized and metabolized locally. The CNS relies on cholesterol 24-hydroxylation as its
major mechanism for eliminating excess cholesterol from the brain. CYP46A1 is an enzyme of
the CNS responsible for hydroxylating cholesterol to 24-hydroxycholesterol (24-OHC), which
can easily pass the blood-brain barrier and leave the brain to travel into the systemic blood
circulation. In fact, 24-OHC plasma level is a specific biomarker for cholesterol homeostasis
and CYP46A1 activity in the brain. 24-OHC is a potent modulator of NMDAR, a receptor system
in the brain whose hypofunctioning can lead to problems of memory and learning performance.
Cyp46a1-/- mice and CYP46A1 transgenic animals established that CYP46A1 is involved in
higher-order brain functions and processes beyond mere cholesterol balance: the Cyp46a1-/-
mice lacking CYP46A1 demonstrated severe deficiencies in spatial, associative, and motor
learning-- as well as deficiencies in long-term potentiation of the hippocampus. On the other
hand, CYP46A1 transgenic animals with an abundance of CYP46A1 had improvements in spatial
memory and significant increase in the levels of NMDAR in the hippocampus. CYP46A1
overexpressing mice possessing an animal model of AD demonstrated improvements in learning
and memory, and reduction in pathological amyloid beta.

Various studies have demonstrated a number of associations between CYP46A1 and AD. For
unknown reasons, this neuron-specific enzyme becomes specifically expressed in astrocytes of
AD patients; plasma levels of 24-OHC, the product of CYP46A1, also change in AD
patients—there are slight elevations of plasma levels in the early stages of AD, followed by
decreases in the later stages of AD, (the elevations have been interpreted to represent
demyelination of the brain and subsequent release of 24-OHC into the systemic circulation,
and the decreases could be attributed to loss of CYP46A1 during the physical process of
neuronal degeneration); and, finally, CYP46A1 is highly polymorphic enzyme with the most
frequent intronic SNPs (rs754203, rs3742376, rs7157609, and rs4900442 being found at ~29- 40%
frequency in the population. The CYP46A1-AD genetic link is, however, unclear, with only
about half of linkage studies establishing the CYP46A1-AD association. Data from several
laboratories point to enhanced metabolism of cerebral cholesterol as a strong anti-AD disease
mechanism.

CYP46A1-mediated metabolism of cerebral cholesterol has never been considered as a
pharmacologic target because the proposed activity requires activation of the enzyme, a
significant challenge for drug developers. Only 5% of drugs on the market act as enzyme
activators, with the majority of pharmaceuticals serving as enzyme inhibitors. Dr. Pikuleva's
laboratory--over the course of more than 10 years' work--overcame this challenge by
ultimately discovering that in mice, CYP46A1 can indeed be activated pharmacologically by
efavirenz (EFV). This CYP46A1 activation also leads to enhanced cerebral cholesterol turnover
in mice.

2.0 STUDY RATIONALE

AD has been shown to be a disease featuring rampant aberrant cerebral cholesterol phenomenon;
hence the AD population is the most appropriate demographic to include in this study. The
investigators expect EFV to be a cerebral cholesterol-metabolism-modifying medication, which
may have prolific uses in neurodegenerative diseases--such as AD--where cholesterol
metabolism is aberrant.

2.1. Risk/Benefit Assessment

EFV is an FDA-approved anti-retroviral medication for use in the adult population-including
the geriatric population. The current recommended dose of Sustiva for adults with HIV is 600
mg daily. This research study will be utilizing very low doses of Sustiva (50 mg and 200 mg),
which are the current dosage ranges for children. The investigators have no reason to believe
that utilizing 1/3 the adult dose of a drug in the geriatric population will increase the
risk of the drug beyond those side effects which are already listed for this product. The
study participants will be monitored very closely throughout the course of the research study
to bring to light any untoward effects in the participants that would outweigh the potential
benefit of this study.

3.0 STUDY OBJECTIVES

3.1. Primary Objectives

- To ascertain if EFV engages CYP46A1 to affect brain cholesterol metabolism,

- To investigate whether EFV increases plasma 24-OHC concentrations, and

- To confirm the safety and tolerability of low doses of EFV,

3.2. Secondary Objectives

● To precisely measure EFV's effect on CYP46A1 activation and CNS-cholesterol turnover via
Stable Isotope Labeling Kinetics (SILK) study.

3.3. Tertiary Objectives

● To conduct post-hoc analysis to investigate whether APOE isorforms and SNPs in CYP46A1 and
CYP2B6 affect study participant response to EFV.

4.0 STUDY DESIGN

4.1. Study Design Overview

A total of 36 patients will be enrolled at 2 sites, 18 patients at the UH site and 18
patients at the MGH site. Site UH, the recruiting clinician at this site is Alan Lerner, MD.
Site MGH, recruiting clinician at this site is Steven Arnold, MD. At each site, subjects will
be divided into 3 groups; Group1 will consist of 6 subjects who will receive 50 mg EFV; Group
2 will consist of 6 subjects who will receive 200 mg EFV and Group 3 will consist of 6
subjects who will receive Placebo.

5.0 CRITERIA FOR EVALUATIONS

5.1. Primary Endpoints

CYP46A1 engagement will be indicated either by a decrease or increase in plasma 24-OHC from
baseline to final time of treatment in the study participants receiving EFV.

CYP46A1 activation will be indicated by ≥ 30% increase in plasma 24-OHC from baseline to
final time of treatment in the study participants receiving EFV. The primary dose selection
criterion for EFV will be to maximize the proportion of subjects that exceed the threshold
for 24-OHC increase, provided there are no associated safety concerns.

A "symptom checklist" will be reviewed and asked of the study participants every two weeks to
ensure that no untoward, serious complications arise from treatment with EFV. It is not
expected that any serious adverse events will occur. All participants will conclude their
treatment with a Post-Study Safety Check Visit during Week 22.

5.2. Secondary Endpoints

Plasma levels of deuterated 24-OHC in patients involved in the SILK study, who will drink
deuterated water, will be measured to evaluate EFV's effect on CNS-cholesterol turnover.

5.3. Tertiary Endpoints

Carriers of the APOE E4 allele could be better responders to the anti-AD effects of EFV
because in the brain, cholesterol output is a function of both APOE-mediated cholesterol
transport and CYP46A1-mediated cholesterol metabolism. Accordingly, if one of these pathways
is impaired, like in APOE E4 carriers, the significance of the other pathway is increased.
Similarly, the CYP46A1 polymorphisms may affect the ability of EFV to increase 24-OHC because
the baseline levels of CYP46A1 and 24-OHC in the carriers of these polymorphisms could be
lower, if these polymorphisms affect CYP46A1 protein levels. Finally, at a high dose (400-600
mg/day), plasma concentrations of EFV depend on the frequent SNP rs3745274 in CYP2B6 that
metabolizes EFV. Genotyping will be carried out by the Molecular Biology and Genotyping
Module at Case Western Reserve University.

6.0 SUBJECT SELECTION

A total of 36 participants, either male or female, will be enrolled between the ages of 55-85
for 22 weeks. Recruitment of study participants will occur during potential participants'
regularly-schedule clinical visits, or from chart review.

6.1. Study Population

All participants should have either mild cognitive impairment or early dementia due to AD,
defined clinically as follows:

- Complaint of cognitive decline

- Mini-Mental Status Examination (MMSE) totaling between 20-30

- Clinical Dementia Rating (CDR) equaling 0.5-1

The 36 study participants will be recruited in a timeframe of approximately 8-9 months. The
two study sites are anticipated to recruit 2 study participants per month. This anticipated
rate is based on the investigators previous experience in clinical study subject enrollment
and high patient volume at the University Hospitals Brain Health and Memory Center and the
Memory Disorders Clinic, and the Memory Disorders Unit and Massachusetts Alzheimer's Disease
Research Center (MADRC) at Massachusetts General Hospitals (MGH).

7.0 CONCOMITANT THERAPIES

Medical history will be collected for all medications at the screening visit and at all
subsequent clinical and telephone follow-up visits. All subjects should be maintained on the
same medications from screening through Visit 7, as medically feasible, with no introduction
of new therapies.If any changes in concomitant medications are made for any reason by the
study participant's personal physician(s), the changes and reason(s) for the change(s) will
be documented.

7.1. Allowed

Except as noted in the prohibited medications section 7.2. Stable use of cholinesterase
inhibitor is permitted if doses are stable for 3 months prior to enrollment.

7.2. Prohibited

EFV is mainly metabolized by CYP2B6 and CYP3A4, and in the 600 mg/day dose range or higher,
has potential interactions with other drugs. Also, EFV is expected to stimulate cholesterol
elimination from the brain, inducing a compensatory upregulation of cerebral cholesterol
biosynthesis; statins that cross the blood-brain barrier would be expected to especially
inhibit cerebral cholesterol biosynthesis and confound 24-OHC biomarking of EFV's effect.
Accordingly, study participants should not have taken the following medications within the
past 3 months: HMG-COA reductase inhibitors (i.e., statins), antiepileptic agents, rifampin,
memantine, buproprion, sertraline, citalopram, zolpidem, aripiprazole, clopidogrel,
capofungin, voriconazole, systemic ketoconazole, cyclosporine, St. John's Wort.

Inclusion Criteria:

- Between the ages of 55-85

- Either male or female

- Diagnosis of (a) as per below:

a) Mild Cognitive Impairment (MCI) or early dementia due to AD as defined by (1)
complaint of cognitive decline, (2) MMSE Total=20-30, (3) CDR=0.5-1

- Fluent in English

- Education >8 years, literate, and/or good working history that precludes consideration
of mental retardation

- Visual and auditory acuity sufficient for neuropsychological testing

- Modified Hachinski Ischemic Score<4

- No major health issues or diseases expected to interfere with the study

- Willing to complete all assessments and study procedures

- Not pregnant, lactating or of child-bearing potential (women must be >2 years post-
menopausal or surgically sterile)

- If cognitively impaired, study partner with frequent contact with patient willing to
accompany patient to visits and complete partner study forms

- No contraindication or hypersensitivity to EFV

- Screening laboratory testing must be within normal limits or, if abnormal, must be
judged to be clinically insignificant by the investigators

- Stable use of cholinesterase inhibitor is permitted if doses are stable for 3 months
prior to enrollment

Exclusion Criteria:

- Any CNS disease other than suspected prodromal or early AD, such as clinical stroke,
brain tumor, normal pressure hydrocephalus, brain tumor, multiple sclerosis,
significant head trauma with persistent neurological or cognitive deficits or
complaints, Parkinson's Disease, frontotemporal dementia, or other neurodegenerative
diseases

- Major psychiatric illness (e.g., depression, bipolar disorder, obsessive compulsive
disorder, schizophrenia) within the previous year

- Current suicidal ideation or history of suicide attempt

- History of alcohol or other substance abuse or dependence within the past two years

- Any significant systemic illness or unstable medical condition that could affect study
compliance, including a history of prolonged QTc

- Laboratory abnormalities in B12, TSH, or other common laboratory parameters that might
contribute to cognitive dysfunction

- Current use of medications with psychoactive properties that may deleteriously affect
cognition (e.g., anticholinergics, antihistamines, antipsychotics, sedative hypnotics,
anxiolytics)

- Use of other investigational agents one month prior to entry and for the duration of
the study

- Treatment with any of the following agents/classes within the past 3 months: HMG-COA
reductase inhibitors (i.e., statins), antiepileptic agents, rifampin, buproprion,
sertraline, citalopram, zolpidem, aripiprazole, clopidogrel, capofungin, voriconazole,
systemic ketoconazole, cyclosporine, St. John's Wort