Protocol Title:Imaging of Cannabinoid CB1Receptors Using [11C]MePPEP
Protocol Number:
Date of Submission: January 9, 2007/Version 1
Lead Associate Investigator:RobertB. Innis, MD, PhD; NIMH /MIB, Bldg 31/B2-B34
(301) 594-1368
Associate Investigators:Janet Sangare, MSN, C-RNP; NIMH/MIB, Bldg31/B2-B34
(301) 451-8861
Amanda Farris, BA; NIMH /MIB, Bldg 31/B2-B34
(301) 594-1381
Garth Terry, BS; NIMH /MIB, Bldg 31/B2-B34
(301) 594-1371
Alicja Lerner, MD/PhD; NIMH /MIB, Bldg 31/B2-B34
(301)451-8894
Research Contact:Amanda Farris, BA; NIMH/ MIB, Bldg 31/B2-B34
(301) 594-1381
Medically Accountable Investigator:
RobertB. Innis, MD, PhD; NIMH/ MIB, Bldg 31/B2-B34
(301) 594-1368
Total Requested Accrual / Number / Sex / AgeRangeHealthy Controls – Brain Imaging (Phase 1) / 15 / M & F / 18-65
Healthy Controls – Whole Body Dosimetry (Phase 2) / 10 / M & F / 18-65
Healthy Controls – Total / 25 / M & F / 18-65
Off Site Project: NO
Project uses ionizing radiation: YES
IND/IDE: YESDrug/Device/# IND not submitted yet
Sponsor: Robert Innis, MD, PhD
Project uses Durable Power of Attorney: NO
Data & Safety Monitoring Board: NO
Technology Transfer Agreement: NO
Samples are being stored: NO
1.Precis
1.1.Brain Imaging
1.1.1.Objective
1.1.2.Study Population
1.1.3.Design
1.1.4.Outcome Measures
1.2.Whole Body Dosimetry
1.2.1.Objective
1.2.2.Study Population
1.2.3.Design
1.2.4.Outcome Measures
2.Introduction/Scientific Rational
2.1.Background
2.2.Development of a PET Ligand for CB1 Receptors
2.3.Background of Approach
3.Study Objectives or Hypotheses
4.Subjects
4.1.Description of Study Populations
4.2.Inclusion Criteria
4.3.Exclusion Criteria
5.Study Design and Methods
5.1.Recruitment - sample composition and characteristics
5.2.Screening
5.3.Study Design
5.4.Study Procedures
5.4.1.Evaluation
5.4.2.Phase 1 – Brain Imaging
5.4.2.1.PET Procedure
5.4.2.2.MRI Procedure
5.4.3.Phase 2
5.4.3.1.PET Procedure – Whole Body Dosimetry
5.5.Termination Procedures
5.5.1.Follow-Up
5.5.2.Transfer of Care/Continuity of Care
5.5.3.Information to be Shared with Subjects and/or Their Health Care Provider
5.6.Research Procedures and Clinical Care
5.7.Pharmaceutical Biologic and/or Device Information
5.7.1.Source
5.7.2.Relevant Pharmacology
5.7.3.Toxicity
5.7.4.Formulation and Preparation
5.7.5.Stability and Storage
5.7.6.Incompatibilities
5.7.7.Administration Procedures
5.8.Radiation Usage
5.9.Relationship to Other Studies Proposed
5.10.Storage of Data and Samples
6.Risks/discomforts
6.1.Medical Examination and Laboratory Testing
6.2.Radiation Exposure Risks
6.3.PET Scanning
6.4.Arterial/Venous line Placement
6.5.Blood Sampling
6.6.MRI
7.Subject Monitoring
7.1.Parameters to be Monitored
7.2.Toxicity Criteria
7.3.Criteria for Individual Subject Withdrawal
8.Outcome measures
8.1.Phase 1 – Brain Imaging
8.2.Phase 2 – Whole Body
9.Statistical analysis
9.1.Analysis of Data/Study Outcomes
9.2.Criteria for Significance
9.3.Sample Size Justification
10.Human subjects protection
10.1.Subject Selection
10.2.Justification for the Exclusion of Children
10.3.Justification for the Inclusion of Other Vulnerable Subjects
10.4.Justification for the Use of Placebo, Medication Washout, or Provocative Stimuli
10.5.Safeguards for Vulnerable Populations
10.6.Qualifications of Investigators
11.Benefits
12.Summary/Classification of risk
13.Consent Documents and Process
14.Data and Safety Monitoring
14.1.Monitoring Plans for the Study
14.2.Criteria for Stopping the Study
15.Adverse Event Reporting
16.Alternatives to Participation or Alternative therapies
17.Confidentiality
18.Conflict of interest/technology transfer
18.1.NIH Investigators
18.2.Participation by a Pharmaceutical Company
19.Compensation
20.References
21.Attachments/Appendices
21.1.Flow Sheets
21.2.Eligibility Checklist
21.3.Clinical Rating Forms (CRFs)
21.4.Rating Scales
21.5.Recruiting Advertisement(s)
21.6.Screening Questionnaires for Patient Recruitment Office
21.7.Investigator’s Brochure
21.8.Reimbursement Schedule
21.8.1.Phase 1: Kinetic Brain Study
21.8.2.Phase 2: Whole body imaging
1.Precis
1.1.Brain Imaging
1.1.1.Objective
The central cannabinoid receptor (CB1) is one of the most abundant neuromodulatory receptors in the brain. It is found on glutamatergic, dopaminergic and GABA-ergic synaptic terminals and belongs to G-protein coupled receptor family. The CB1 is a target for drug therapy, including the use of an antagonist as an appetite suppressant. The central cannabinoid receptor CB1 has never been visualized in humans. In collaboration with Eli Lilly, we developed a promising PET ligand for the CB1 receptor: [11C]MePPEP. This study is known by Eli Lilly as “H6O-MC-GCEB.”
1.1.2.Study Population
In the current protocol, we wish to evaluate [11C]MePPEP in approximately 15 healthy subjects.
1.1.3.Design
Brain imaging studies will consist of subject evaluation followed by PET and MRI scans.
1.1.4.Outcome Measures
We intend to determine the kinetics of brain uptake and washout, clearance in the plasma, and the distribution volume of [11C]MePPEP calculated with compartmental modeling. Distribution volume is proportional to the density of receptors and is equal to the ratio at equilibrium of uptake in brain to the concentration of parent radiotracer in plasma.
1.2.Whole Body Dosimetry
1.2.1.Objective
Should the brain imaging studies prove to be successful, we will continue with whole body dosimetry studies. Preliminary dosimetry studies with [11C]MePPEP have been performed in nonhuman primates, however these need to be continued in humans before further investigation of this novel tracer can continue. This study is known by Eli Lilly as “H6O-MC-GCEC.”
1.2.2.Study Population
In the current protocol, we wish to evaluate [11C]MePPEP in approximately 10 additional healthy subjects.
1.2.3.Design
The whole body dosimetry studies will consist of subject evaluation followed by a PET scan.
1.2.4.Outcome Measures
We intend to determine the whole body distribution of activity and thereby calculate radiation exposure to organs of the body.
2.Introduction/Scientific Rational
2.1.Background
The central cannabinoid receptor was discovered relatively recently (Matsuda et al 1990). It mediates the effects of the naturally occurring ligands (endocannabinoids), anandamide, noladin ether, virodhamine and 2-arachidonylglycerol, which are neurotransmitters and plant derived Δ-9- tetrahydronannabinol(THC, dronabinol), that is the primary psychoactive ingredient in Cannabis sativa.
The CB1 receptor has widespread distribution in the body. CB1 receptors are found in several brainareas(cerebellum, basal ganglia, hippocampus, cortex, hypothalamus, and pituitary gland), and in a variety of peripheral tissues, including adipose tissue, gastrointestinal tract, adrenal glands, sympathetic ganglia, heart, lung, liver, testis, eye, and urinary bladder. Endocannabinoids, such as anandamide and 2-arachidonylglycerol have a protective role in excitotoxicity. Altered endocannabinoids function is encountered in several neurological disorders (Parkinson disease, Huntington disease,and Alzheimer disease), psychiatric (schizophrenia) and eating disorders (anorexia nervosa and binge eating).
The CB1 receptor is one of the most abundant neuromodulatory receptors in the brain and CB1 receptor accounts for the effect of THC on memory, cognition, mood, sensory perception, appetite, pain, catalepsy, tremor, and decreased body temperature. In the monkey it was found in cortex, hippocampus, cerebellum, basal ganglia and amygdala, a high density of these receptors was observed in substantia nigra pars compacta, cerebellar Purkinje cells and the principal cells of hippocampus (Ong and Mackie 1999). In human brain some studies found the highest density of receptors in the substantia nigra pars reticulata (SNpr), globus pallidus, hipocampus and cerebellum (Glass et al 1997; Herkenham et al 1990) whereas other (Mailleux et al 1992) found CB1 receptors in caudate, putamen, all cortical layers and hippocampus and cerebellum. The receptor is found in presynaptic and postsynaptic locations. The CB1 receptor belongs to the G protein-coupled receptor superfamily (Matsuda et al 1990). It is coupled in an inhibitory fashion to adenylate cyclase and both N- and P/Q-type calcium channels (Howlett 1985; Mackie and Hille 1992), and it has been shown to activate an inwardly rectifying potassium conductance (Mackie et al 1995). Inhibition of presynaptically located CB1 receptor coupled to calcium channels was proposed to lead to decreased neurotransmitter release from axon terminals. At presynaptic sites CB1 receptors function as retrograde messengers, which are released postsynaptically, travel backward across the synapses to suppress neurotransmitter release from axon, through inhibition of presynaptic calcium channels (Wilson and Nicoll 2002).
2.2.Development of a PET Ligand for CB1 Receptors
Via a CRADA (Cooperative Research and Development Agreement) with Eli Lilly, we developed a novel PET radioligand for CB1 receptors. [11C]MePPEP was studied in approximately 8 scans in monkeys at NIH and showed excellent properties. In brief, brain uptake was high (~463+/- 116 %SUV at 46+/-22 min post injection), had a regional distribution appropriate for CB1 receptor, washed out quickly, and could be displaced by agents selective for the CB1 receptor. A representative time-activity curve is shown below in Figure 1.
We also studied the biodistribution of [11C]MePPEP in two monkeys to estimate radiation exposure to organs of the body. Lisa Coronado of the NIH RSC approved our analysis of the imaging data. We found that the tracer caused relatively low radiation burden, with an Effective Dose of 24.5 mrem/mCi. Our proposed injected activity of 20 mCi would yield 490 mrem, well below the NIH annual limit of 5,000 mrem.
We will soon apply to the FDA for an IND to study [11C]MePPEP. Of course, we will not begin any research without their approval.
2.3.Background of Approach
This protocol describes the use of a new PET radiotracer and follows some but not all aspects of the previously approved template for initial human use. The prior template had two components: whole body imaging for measurement of organ dosimetry and kinetic imaging of the brain. New Guidance from the FDA on the so-called "ExploratoryIND." ( has allowed a new path for PET radiotracers. The initial human studies should evaluate whether the tracer is useful in a "limited" number of human subjects. If it is, then additional studies are justified. If not, then no further studies will be done, and the whole body dosimetry studies will have been avoided.
On July 28, 2005, the NIH Radiation Safety Committee reviewed the Guidance on ExploratoryIND and supported this approach. In addition, the NIMH Council at its February and May 2005 meetings has reviewed ways to reduce the regulatory barrier for introduction of new radiotracers in man The Council has supported reduced barriers such as the exploratory IND, written a letter to the FDA to this effect, and had the FDA Director of Medical Imaging (George Mills, MD) speak at its May 2005 meeting.
3.Study Objectives or Hypotheses
The protocol has two objectives:
1) Phase 1 will be performed to test the accuracy of CB1 binding parameters in brain using [11C]MePPEP PET imaging with arterial data in healthy volunteers
2) Phase 2. If phase 1 is successful, we will proceed to phase 2 during which we will estimate radiation-absorbed doses of [11C]MePPEP in healthy human subjects by performing whole body imaging.
4.Subjects
4.1.Description of Study Populations
We will select fifteen healthy adult female and male volunteers (age 18–65 years old) for brain imaging and ten healthy volunteers for whole body dosimetry analysis. We will exclude children or minors because this study involves radiation exposure. The proportion of ethnic minorities (vs. Caucasians) in the total sample will approximately be consistent with the overall U.S. population proportions
4.2.Inclusion Criteria
All subjects must be healthy and aged 18–65 years, with history/physical exam, ECG, and laboratory tests within one year of the PET scan. The volunteer must sign an informed consent form.
4.3.Exclusion Criteria
1)Current psychiatric illness, substance abuse including marijuana use, or severe systemic disease based on history and physical exam.
2)Laboratory tests with clinically significant abnormalities or positive urine toxicology screen.
3)Prior participation in other research protocols in the last year such that radiation exposure would exceed the annual limits.
4)Pregnancy and breast feeding.
5)Claustrophobia.
6)Presence of ferromagnetic metal in the body or heart pacemaker.
7)Positive HIV test.
8)Employee of the investigative site or an immediate family member of an employee of the investigative site. Immediate family member is defined as a spouse, parent, child, or sibling, whether biological or legally adopted.
9)Employee of Eli Lilly and Company.
5.Study Design and Methods
5.1.Recruitment - sample composition and characteristics
Twenty-five healthy controls will be studied. All subjects must meet the inclusion and exclusion criteria listed in Sections4.2 and 4.3. We will select healthy adult female and male volunteers in this protocol.
We will initiate the study within 1–2 months of final approval. Healthy controls meeting inclusion and exclusion criteria (above) will be recruited from the community and NIH through advertisements in newspaper, newsletter, and the NIH website, private physicians and social service agencies. We will obtain informed consent from all healthy controls.
5.2.Screening
Healthy volunteers will be screened at NIH for meeting the inclusion or exclusion criteria.
5.3.Study Design
This study will proceed in 2 phases.
Phase 1. This phase entails three components: Evaluation, MRI, and PET. The MRI will be obtained within one year of the PET scan, i.e., up to one year before or one year after the PET scan. All subjects will have an initial visit(s) for evaluation: physical/history, laboratory screening tests. The subjects must be documented to meet inclusion and exclusion criteria and sign an informed consent. Evaluation, MRI, and PET sessions will take approximately 3 h, 1 h, and 5 h, respectively.
During Phase 1 we will assess the accuracy of measuring CB1receptor levels by dynamic brain PET imaging using [11C]MePPEP and we will perform a quantification study in 10-15 normal subjects. We will quantify CB1binding parameters to determine the reliability of these parameters using [11C]MePPEP. The injected dose for Phase 1 subjects is expected to be 20 mCi based on whole body dosimetry of [11C]MePPEP in rhesus monkeys. Phase 1 will include subject’s evaluation, PET scan, and post-scan safety monitoring laboratory tests. Evaluation and PET sessions will take approximately 3 h and 5 h, respectively.
Phase 2. We will proceed to Phase 2 only if resultsofPhase 1 showed stable values of receptor density measured as distribution volume calculated with compartmental modeling.
In Phase 2 we will estimatehuman dosimetry of [11C]MePPEP by performing whole body imaging studies in 10 healthy subjects (approximately 5 males and 5 females). Our available human dosimetry data has been estimated from non-human primate biodistribution studies. Injection dose in this second part of the protocol is expected to be approximately 10 mCibased on the results of the whole body imaging studies in rhesus monkey.
5.4.Study Procedures
5.4.1.Evaluation
Healthy volunteers will be evaluated at NIH. A 12-lead EKG will be obtained, and subjects will be asked to provide blood and urine samples for a battery of laboratory screening tests such as complete blood count including platelet count, chemistries (Na, K, Cl, HCO3, BUN, Cr, glucose, Ca, PO4, SGOT, SGPT, LDH, alkaline phosphatase, CPK, bilirubin, total protein, albumin), RPR, urinalysis, and urine drug screen. All women of child bearing potential will have a blood pregnancy test within 24 h prior to the PET and MRI scans.
5.4.2.Phase 1 – Brain Imaging
5.4.2.1.PET Procedure
The NIMH Radiochemistry Laboratory (Dir., Victor Pike, PhD) will synthesize and perform QC (quality control) for[11C]MePPEP.
All women of child bearing potential will have a blood pregnancy test again within 24 h prior to the PET tracer injection.
PET dynamic brain scanning will be performed using the GE Advance or HRRT in the PET Department. Subjects will be placed on the scanner bed with his/her head held firmly in place with a thermoplastic mask fixed to the bed. One antecubital venous and one radial arterial catheter will be placed. An anesthesiologist will place the arterial catheter in the subject’s wrist after numbing the area with Novocain prior to the placement to minimize discomfort. The anesthesiologist will attempt no more than two (2) skin punctures in one arm to place the arterial line before trying in the other arm. The venous catheter is for radioligand injection and the arterial catheter is for blood sampling. Prior to beginning the PET scan procedure, a baseline blood sample will be drawn for the laboratory tests, and a transmission scan will be performed with a 68Ge rotating pin source to provide a measured attenuation correction. The radiation-absorbed dose from a transmission scan was estimated to be 0.05 rad to the red marrow, lens of eyes, thyroid, and the brain (based on measurement by M. Daube-Witherspoon, Ph.D., memo of Nov 29, 1994). The radioligand(20 mCi of [11C]MePPEP) will be injected intravenously as a bolus injection. The dosage of 20 mCi of [11C]MePPEP was selected for several reasons. First, it is safe from a radiation safety perspective and would cause an estimated ED of ~0.5 rem. In addition, this is an exploratory IND with the purpose of determining whether the tracer is useful for CB1 receptor imaging. For this purpose, we plan to scan for 2.5 hours – i.e., approximately eighthalf-lives. Thus, little activity will remain at the end of the study. The latter portions of the brain time activity curve (90 – 150 min) will be particularly important to examine for radiolabeled metabolites (which would be evidenced by an increasing transient volume of distribution). Finally, we hope to obtain plasma measurements of parent radiotracer and metabolites for the entire period. We need to start with adequate activity to have measurable amounts at the end of the experiment.
To measure input function of the radioligand, blood samples will be obtained frequently from the arterial line. Several venous samples will also be obtained at several time points to estimate arterial input function using venous blood data. Blood sampling volume will be no more than 250 mL.
5.4.2.2.MRI Procedure
Subjects will have an MRI scan for anatomical localization by coregistering onto PET image. MRI scanning will be done on a 1.5 Tesla scanner located at the NIHClinicalCenter. Transaxial and coronal scans will be acquired in a spoiled GRASS (SPGR) gradient echo pulse sequence. MRI will take up to 1 hour.
If subjects become anxious during a scan lorazepam (Ativan0.5–1mg) may be administered orally.
Brain imaging study (Phase 1)
1st VisitScreen / 2nd Visit / 3rd Visit / 4thVisit
Time - weeks / 0 / 24 / 24
Informed consent /
Physical Exam /
Neurological Exam /
Pregnancy test (female ≤ 55) / / * / *
MRI / **
Brain PET /
Blood and urine tests / / / / #
*A pregnancy test will be done within 24 h prior of PET ligand administration and the MRI scan.
**Depending on the availability of PET and MRI scanners, an MRI scan may be scheduled at any point in time for this protocol, either before or after the PET procedures.
#The blood and urine samples will be taken approximately 24 h after PET procedure. If the subjects cannot come to the ClinicalCenter at above mentioned time, the blood and urine samples will be taken shortly after the PET procedure.