Investigation of Cannabidiol for Reduction of NeuroInflammation in Chronic Back Pain
Phase: PHASE4
Conditions: Back Pain, Low
Sponsor: Massachusetts General Hospital

 
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DETAILED PROTOCOL  
 
Investigation of Cannabidiol for Reduction of NeuroInflammation  
in Chronic Back Pain 
 
NCT # NCT03891264 
11/12/2020 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
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DETAILED PROTOCOL: 
 
Investigation of Cannabidiol for Reduction of NeuroInflammation  
in Chronic Back Pain 
 
PI: Jodi Gilman, PhD 
Co-PI: Marco Loggia, PhD 
Co-I: A. Eden Evins, MD 
Co-I: Yi Zhang, MD 
Co-I: Jianren Mao, MD  
Co-I: Kristina Schnitzer, MD 
 
Date: 11/12/2020 
 
 
BACKGROUND AND SIGNIFICANCE 
 
Millions of individuals suffer from chronic pain  
Chronic pain is defined as pain without apparent biological value that has persisted 
beyond the normal tissue healing time (usually taken to be 3 or 6 months 1,2). Chronic 
pain is a widespread public health issue 3, and its prevalence is enormous. The weighted 
mean prevalence of chronic pain in the general population has been estimated by some at 
35.5%, or 105 million, in the United States 4. Not only does chronic pain affect both 
physical and mental functioning, thus compromising quality of life; it is also associated 
with astronomical costs. In addition to the direct costs of treating pain—including health 
care for diagnosis and treatment, drugs, therapies, and other medical expenses—chronic 
pain results in lost work time and reduced productivity 5,6. Past estimates of the annual 
cost of chronic pain in the United States, including healthcare expenses, lost income and 
productivity, were close to $100 billion 7.  
  
 
Treatment for chronic pain is unsatisfactory 
Despite the enormity of the phenomenon, clinical needs for chronic pain are largely 
unmet. The treatment of choice for the largest majority (as many as 90% 8) of patients 
seeking chronic pain management is based on opioid analgesics. However, the evidence 
supporting long-term effectiveness of opioid drugs in relieving pain and improving 
functional status is weak 9. For instance, despite the widespread use of opioids for 

 
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palliative care, more than half of all hospitalized patients experience pain in the last days 
of their lives, and 50-75% of cancer patients die in moderate to severe pain 10. 
 
The current opioid-based pharmacological approaches to treat chronic pain are not only 
ineffective, but they generally have multiple unpleasant side effects, including 
constipation, pruritus, respiratory depression, nausea, vomiting, hyperalgesia, dizziness, 
sedation 9, as well as abuse and dependence 8,11,12. Taken together, the unsatisfactory 
treatment efficacy and the occurrence of significant side effects, clearly stress the 
importance of achieving a deeper understanding of the pathophysiological mechanisms 
underlying chronic pain, in order to eventually identify viable treatment options 
alternative to ones currently available.  
 
 
Microglia and pain 
One of the reasons for the poor efficacy of the treatment options currently available for 
chronic pain might be that these are primarily aimed at suppressing neuronal activity 
within nociceptive pathways of the nervous system. However, it is now increasingly clear 
that neurons are far from being the only players that drive the establishment and/or 
maintenance of clinical pain symptoms. Rather, evidence from animal studies now 
suggests a central role of glial cells in the nervous system, including microglia 13,14.  
 
Microglia are a subpopulation of macrophages that rapidly activate in response to a 
variety of pathological conditions 15, including persistent pain 16-23. Microglial activation 
(MA) is characterized by a stereotypic pattern of cellular responses, including specific 
morphological changes, proliferation, increased or de-novo expression of cell surface 
markers or receptors, and migration to the site of injury 24. MA generally represents an 
adaptive homeostatic defense response which enables the destruction of invading micro-
organisms, the removal of potentially deleterious debris as well the promotion of tissue 
repair. However, animal studies have now showed that the uncontrolled activation of 
microglial cells under pathological pain conditions induces the release of substances that 
can sensitize pain pathways, such as proinflammatory cytokines, complement 
components, and others 25. While evidence of pain-related MA was originally observed in 
the spinal cord, more recently it was also discovered at the level of the brain, including in 
the rostral ventromedial medulla 20,26, the trigeminal nuclear complex 19,27, and the ventral 
posterolateral nucleus of the thalamus 28,29.  
 
While most of the evidence on the occurrence of pain-related glial responses in the 
central nervous system comes from animal studies, a few important observations indicate 
that similar phenomena should occur also in humans 13. First, immunohistochemical 
markers of microglial and astroglial activation have been detected in the spinal cord of a 
patient with chronic regional pain syndrome in a postmortem study 30. Furthermore, an 
increase in the concentration of the glial marker s-100β was reported in the cerebrospinal 
fluid of patients with lumbar disc herniation and in the serum of children with recurrent 
headaches 31,32. Finally, a positron emission tomography (PET) study has revealed that 

 
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human subjects with neuropathic pain secondary to peripheral nerve damage express 
increased thalamic binding for [11C](R)-PK11195 33, an in vivo marker of microglial cell 
activation 34,35. 
 
Recently, Co-PI Dr. Marco Loggia has also shown that patients with chronic low back 
pain (cLBP) have increased brain levels of the 18kDa translocator protein (TSPO), a 
marker of glial activation36. In addition, preliminary data collected from a different cohort 
of patients with cLBP and sciatica suggest an increase in spinal cord TSPO levels. 
Together, these results suggest that human chronic pain conditions are likely to be 
associated with a glial reaction, both in the spinal cord, as well as in the brain.  
 
 
Cannabidiol and pain 
There is a growing body of evidence to suggest that cannabinoids are beneficial for a 
range of clinical conditions, including pain, inflammation, epilepsy, and sleep disorders37. 
A large body of preclinical and clinical research indicates that the cannabinoid system 
modulates a broad range of physiological processes and behaviors including, but not 
limited to, pain, mood, appetite, neuronal activity, memory, immunity, and cell 
development. The endocannabinoid system’s contribution to the regulation of such a 
variety of processes makes phytocannabinoid pharmacological modulation a promising 
therapeutic strategy 38. 
 
The primary cannabinoids found in the cannabis plant include delta-9 -
tetrahydrocannabinol (THC), cannabidiol (CBD), and cannabinol (CBN), with THC 
being the primary psychoactive compound. The second most abundant compound in the 
plant is CBD, which is minimally psychoactive 39. Cannabinoid receptor type 1 (CB1) 
and type 2 (CB2) belong to a family of seven transmembrane Guanosine Binding Protein-
Coupled Receptors, and are widely expressed and distinguished by their specific 
functions, localization and signaling mechanisms. The psychotropic effects of cannabis 
are principally mediated by CB1, which is widely distributed throughout the brain, while 
CB2 is considered the peripheral cannabinoid receptor, found mainly in immune cells, as 
well as in chondrocytes, osteocytes and fibroblasts. Agonists targeting CB2 receptors 
have been proposed as therapies for the treatment or management of a range of painful 
conditions, including acute pain, chronic inflammatory pain, and neuropathic pain 40. In a 
preclinical model, researchers showed that stimulation of CB2 suppresses microglial 
activation 41.  
 
In the current study, we will test whether CBD is a glial inhibitor in patients with chronic 
lower back pain (cLBP). CBD was recently FDA-approved as a liquid formulation (see 
EPIDIOLEX package insert) for epilepsy for children ages 2 and up as well as adults, 
demonstrating significant reductions in total seizure frequency with minimal side effects. 
It is unclear whether cannabidiol reduces glial activation in humans. We will study 20 
patients with low back pain (pain duration > 6 months) longitudinally before and after 4 

 
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weeks of treatment with cannabidiol. Endpoints will be pain scores as well as brain levels 
of the 18kDa translocator protein (TSPO), a marker of glial activation36. 
 
 
SPECIFIC AIMS 
 
Primary Aim: Assess whether CBD reduces neuroinflammation in patients with 
cLBP. 
 
Hypothesis: Patients will demonstrate higher PET signal in the brain (thalamus, S1/M1 
representation of the lumbar spine) before CBD treatment in comparison to after CBD 
treatment. This within-subject comparison will allow us to evaluate short-term change 
over time in cLBP patients. 
 
SUBJECTS SELECTION 
 
We plan to identify 20 patients with chronic low back pain (cLBP; i.e., with a pain 
duration longer than 6 months), who will complete the study.  
 
We are not planning to enroll subjects from at-risk populations (e.g., children and minors, 
cognitively impaired persons, prisoners). Written informed consent form will be obtained 
in all cases.   
 
Inclusion Criteria:  
- 
age ≥ 18 and ≤ 75;  
- 
the ability to give written, informed consent;  
- 
ongoing pain that averaged at least 4, on a 0-10 scale of pain during a 
typical week, and present for at least 50% of days during a typical week; 
- 
on a stable pain treatment (pharmacological or otherwise) for the previous 
four weeks.  
- 
Chronic low back pain, ongoing for at least 6 months prior to enrollment.  
 
Exclusion Criteria:  
- 
outpatient surgery within 2 months and inpatient surgery within 6 months 
from the time of scanning; 
-  
elevated baseline transaminase (ALT and AST) levels above 3 times the 
Upper Limit of Normal (ULN), accompanied by elevations in bilirubin 
above 2 times the ULN 
- 
any interventional pain procedures within 6 weeks prior to scanning 
procedure or at any point during study enrollment; 
- 
surgical intervention or introduction/change in opioid regimen at any point 
during study enrollment  
- 
contraindications to fMRI scanning and PET scanning (including presence 

 
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of a cardiac pacemaker or pacemaker wires, metallic particles in the body, 
vascular clips in the head or previous neurosurgery, prosthetic heart 
valves, claustrophobia);  
- 
current or past history within the last 5 years of major medical illness not 
affecting the central nervous system, other than chronic pain;  
-  
implanted spinal cord stimulator (SCS) for pain treatment; 
- 
any history of neurological illness or major medical illness affecting the 
central nervous system, unless clearly resolved without long-term 
consequences; 
- 
current or past history of major psychiatric illness;  
- 
PTSD, depression, and anxiety are exclusion criteria only if the 
conditions were so severe as to require hospitalization in the past  
year. 
- 
pregnancy or breast feeding; 
- 
history of head trauma requiring hospitalization;  
- 
major cardiac event within the past 10 years; 
- 
any use of recreational drugs in the past 3 months; 
- 
any marijuana use, medical or recreational, in the past 3 months; 
- 
an abnormal physical exam (e.g., peripheral edema); 
-  
use of immunosuppressive medications, such as prednisone, TNF 
medications within 2 weeks of the visit; 
- 
current bacterial or viral infection; 
-  
epilepsy or any prescription of an anti-epileptic drug  
-  
use of the medications valproate and clobazam, which may increase risk of 
hepatic AEs  
- 
use of medications with:  
-  
Strong and moderate CYP3A4 inhibitors including boceprevir, 
cobicistat, conivaptan, danoprevir, elvitegravir, ritonavir, indinavir, 
itraconazole, ketoconazole, lopinavir, paritaprevir and ombitasvir 
and/or dasabuvir, posaconazole, saquinavir and telaprevir, 
tipranavir, clarithromycin, diltiazem, idelalisib, nefazodone, 
nelfinavir, troleandomycin, voriconazole, aprepitant, cimetidine, 
ciprofloxacin, clotrimazole, crizotinib, cyclosporine, dronedarone, 
erythromycin, fluconazole, fluvoxamine, imatinib, tofisopam, 
disulfiram, and verapamil; 
-  
Strong and moderate inhibitors of CYP2C19 including fluoxetine 
and ticlopidine; 
- 
Sensitive and moderately sensitive substrates of CYP2C19 
including clobazam, lansoprazole, omeprazole, S-mephenytoin, 
and rabeprazole; 
-  
Sensitive and moderately sensitive substrates of CYP1A2 
including alosetron, duloxetine, melatonin, ramelteon, tasimelteon, 
theophylline, tizanidine, pirfenidone, and ramosetron; 

 
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-  
Sensitive and moderately sensitive substrates of CYP2B6 
including bupropion and efavirenz; 
-  
Sensitive and moderately sensitive substrates of CYP2C8 
including repaglinide, montelukast, pioglitazone, and rosiglitazone; 
-  
Sensitive and moderately sensitive substrates of CYP2C9 
including tolbutamide, celecoxib, glimepiride, and warfarin; 
-  
Sensitive and moderately sensitive substrates of UGT1A9 
including diflunisal, propofol, and fenofibrate; 
-  
Sensitive and moderately sensitive substrates of UGT2B7 
including, gemfibrozil, lamotrigine, and morphine; 
-  
The following CNS depressants including all antipsychotics, 
benzodiazepines (except for alprazolam, clonazepam, and lorazepam), and 
the non-benzodiazepine sleep aids including butabarbital sodium, 
eszopiclone, phenobarbital, ramelteon secobarbital sodium, suvorexant, 
zaleplon, and zolpidem; 
-  
regular use of opioids 
- 
actively suicidal, history of suicide attempt or an aborted attempt within 
the last 5 years, or engagement in non-suicidal self-injurious behavior 
within the last year 
- 
Any other contraindications to CBD administration noted by the study  
physician. 
 
SUBJECT ENROLLMENT  
 
Subjects will be recruited through advertising by flyers and printed announcements 
posted within as well as outside of our Partners community. In addition, email, web and 
bulletin board announcements posted in the community will be used. We will also use the 
Partners’ RSVP for Health system, Partners Clinical Trials, as well as ResearchMatch, a 
database of research volunteers developed by Vanderbilt University and approved for use 
by the PHRC. In addition, methods that advertise the study to the greater community will 
be used such as social media posts, posting flyers on community billboards in the greater 
Boston area, emails to physicians and family medicine centers, and advertisements in 
newspapers etc. will be adopted. Advertisements will briefly describe the study and invite 
subjects to call if they are interested. All subjects will undergo a telephone screening to 
attempt to distinguish potential subjects from those not meeting eligibility criteria. 
Informed consent will be obtained from all subjects before initiating any study 
procedures at study visit #1 (Behavioral visit). 
 
During screening, potential participants will be fully informed of the purpose and 
activities involved in the research study. Interested subjects will be scheduled for an in-
person visit where written informed consent will be immediately obtained, prior to 
initiating any of the study procedures. One copy of the signed consent form will be given 
to the patient and one will be kept in the study files for documentation. No time limits 

 
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will be imposed on the informed consent process. Participants will be permitted to take as 
much time as they desire to engage in the informed consent process; any and all of their 
questions will be answered. It is anticipated that obtaining written informed consent will 
take approximately 15-25 minutes, on average. Comprehension of the consent 
information will be assessed via solicitation of answers to questions throughout the 
process. If comprehension appears to be limited, participants will be actively queried to 
determine whether they need further explanation.  
 
A physician member of the staff will obtain informed consent, as in all other protocols 
involving [11C]PBR28 PET/MR scanning (e.g., 2011P002311). 
 
 
STUDY PROCEDURES 
 
After a behavioral visit aimed at determining eligibility, subjects will be scheduled for 
their first imaging visit, during which they will undergo a simultaneous MR-PET scan. At 
this visit, subjects will receive CBD. During the drug trial period, subjects will also be 
sent a daily survey to assess the treatment effect of the medication on their pain. As soon 
as possible after the end of the 4-week drug trial period, all subjects will be scanned 
again.  
 
Investigational Agent 
Epidiolex, an agent within the anti-epileptic drug class, will be used. Epidiolex, 
Greenwich Biosciences Inc.’s CBD formulation, is a 100 mg/mL purified oral solution, 
dissolved in the excipients sesame oil and anhydrous ethanol with added sweetener 
(sucralose) and strawberry flavoring. The drug is formulated from extracts prepared from 
Cannabis sativa L. plants that have a defined chemical profile and contain consistent 
levels of CBD as the principal phytocannabinoid. Extracts from these plants are 
processed to yield pure (>95%) CBD that typically contains less than 0.5% (w/w) THC. 
Cannabidiol is the active ingredient in Epidiolex; inactive ingredients include dehydrated 
alcohol, sesame seed oil, strawberry flavor, and sucralose. Of note, CBD has no 
psychoactive properties. The empirical formula of Epidiolex is C21H30O2 and its 
molecular weight is 314.46. The structure of CBD is provided in the figure below.  
 
 
Figure 1. Cannabidiol Structure 
 

 
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Dose and Exposure 
The recommended starting dosage is 2.5mg/kg taken twice daily (5mg/kg/day). 
Participants will follow a titration schedule, with 5 mg/kg/d in week 1, 10 mg/kg/d in 
week 2, 15 mg/kg/d in week 3, and 20 mg/kg/d in week 4. Subjects will increase to 20 
mg/kg/d on the first day of the final week of the study (week 4) and take Epidiolex at this 
dose for the remainder of this final week. If participants report AEs (tiredness, dizziness, 
not tolerating the medication well), the physician will decrease the dose by 5 mg/kg. 
Participants will be treated for 4 weeks in total. 
 
The 4-week duration of CBD administration is proposed because in the current study, we 
are investigating an endophenotype of pain- neuroinflammation- which may be detectable 
before verbal reports of pain reduction, which is notoriously noisy and susceptible to 
placebo effects. This pilot study will inform us of whether 4 weeks is enough to detect 
changes in TSPO binding that may precede verbal reports of pain reduction.   
 
Screening visit: Subjects eligible to participate will be recruited to participate in a 3-hour 
characterization session. In this session, we will obtain a signed consent form from the 
subjects, explain the procedures involved in the experiment, and administer some or all of 
the following validated assessments. We will also collect detailed contact information 
(address, social security number, medical record number) as well as collect a blood 
sample and a urine sample. Computer-based rating scales and questionnaires will be 
completed on a laptop. All assessments will be performed by fully trained study staff 
members such as post-doctoral research fellows and Clinical Research Coordinators, 
under the supervision of and periodic monitoring by the Principal Investigator (PI).  
 
Many of these assessments are already in use in one or more IRB approved protocols 
(e.g., 2011P002311). 
 
Hospital Anxiety and Depression Scale (HADS): The HADS is a 14-item self-report 
survey designed for populations with medical illness42. It does not include somatic 
symptoms, such as fatigue and sleeplessness, which may otherwise be attributable to 
pain. It asks patients to rate depression and anxiety symptom over the past week on a 4-
point Likert scale. It has been validated in several medical illness populations and has 
been used extensively in chronic pain patients. This scale will be repeated at Baseline 
scan, 2-week visit, and 4-week visit, and any significant increase will warrant clinical 
attention. If there is more than a 30% increase in symptoms of anxiety or depression, this 
will be immediately reported to the PI, who will consult with study clinicians. Clinicians 
will them determine, with the participant, whether it is in their best interest to continue 
the medication. 
 
The Pain Catastrophizing Scale (PCS): It is a 13-item self-report scale which measures 
pain-related Rumination, Magnification and Helplessness43. 
 

 
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PainDETECT44: The PainDETECT is a screening questionnaire used to estimate the 
likelihood of a neuropathic component in chronic pain. 
 
Social Provisions Scale (SPS): The social provisions scale measures the social support 
provided by the patient’s current relationships.45 
 
Snaith-Hamilton Pleasure Scale (SHAPS)46: The Snaith-Hamilton survey is a 14-item 
questionnaire designed to estimate the degree to which an individual is able to experience 
pleasure, or the anticipation of pleasure. The questionnaire assesses four domains of 
hedonic experience: interest/pastimes, social interaction, sensory experience, and 
food/drink. All items relate to daily experiences encountered by most people.  
 
Fibromyalgia Survey Questionnaire (FSQ)117: The Fibromyalgia Survey Questionnaire is 
a 5-item questionnaire that is aimed at assessing the presence of fibromyalgia, or pain 
centralization, subclinically in people who do not meet the fibromyalgia criteria. 
 
History and physical examination: an MD or NP will also collect medical history and 
perform a formal physical examination, including the recording of vital signs (heart rate, 
blood pressure, and body temperature). 
 
Suicidal Ideation. The Columbia-Suicide Severity Rating Scale (C-SSRS) (Posner et al., 
2010) will be used for prospective suicidality assessment. C-SSRS is a tool used to assess 
the lifetime suicidality of a participant and to track suicidal events through the treatment. The 
structured interview prompts recollection of suicidal ideation, including the intensity of the 
ideation, behavior and attempts with actual/potential lethality. The scale will be administered by 
study staff at the screening visit, baseline, two-week visit, and four-week visit. The C-SSRS 
“Screening/Baseline” will be collected at Screening and Baseline and the C-SSRS “since last 
visit” will be collected at subsequent visits. Participants who answer “yes” to any suicidal 
behavior questions or to suicidal ideation questions 4 or 5 on the C-SSRS during the study should 
be referred for appropriate psychiatric care. If there is more than a 30% increase in symptoms of 
anxiety or depression, this will be immediately reported to the PI, who will consult with study 
clinicians. Clinicians will then determine, with the participant, whether it is in their best interest 
to continue the medication. The decision to discontinue the participant from the study will be 
made by the PI in conjunction with clinical Co-Investigators.  
 
Safety monitoring: As participant suicidality and depression is monitored throughout the 
study with the C-SSRS and BDI questionnaires, any new or worsening expression of 
suicidal ideation or Answers of "Yes" to questions 4 or 5 on C-SSRS throughout the 
study will be evaluation by a licensed clinician member of study staff. The Standard 
Operation Procedure will be reviewed. To summarize, if any risk for self-harm or 
suicidality is identified at visit 1, visit 3, or visit 4, the research coordinators will 
immediately report this to study clinicians, who will determine whether a safety 
assessment is needed. If a clinician is needed to perform a safety assessment, study staff 
will record the date, clinician initials, and comments related to the suicidality assessment 

 
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in the Study Trax C-SSRS module. Following the initial suspicion or identification of 
self-harm and/or suicidality, a study clinician will follow up with the participant on the 
current nature of their situation, querying about any new ideation, intent, and/or plan 
since the last visit. These clinicians, along with the PI will then determine whether a 
participant can safely continue the study. If the clinicians determine that the participant 
cannot safely continue the study, the participant will be discontinued, and will be 
provided with a list of resources for follow-up care. 
 
Blood tests: a trained member of the study staff will draw venous blood (up to 10 ml) 
from all subjects in order to have them genotyped for the Ala147Thr TSPO 
polymorphism in the TSPO gene (rs6971) (unless this genotype information is already 
available), and to check liver enzyme values. Additionally, during screening for 
eligibility, we will conduct routine chemistry and LFT/GGT. We will obtain serum 
transaminases (ALT and AST) and total bilirubin levels in all patients prior to starting 
treatment with CBD.  
 
While [11C]PBR28 has the advantage of binding to the TSPO protein with a higher ratio 
of specific-to-nonspecific binding than [11C](R)PK1119547, it also presents a potential 
limitation, in that about 10% of human subjects show no binding to PBR2848 (whereas  
[11C](R)-PK11195 has never been associated with non-binding49). A recent study has 
demonstrated that the rs6971 polymorphism predicts PBR28 binding affinity in human 
platelets50. Since the low-affinity binder phenotype is consistent across all tissues within 
the same subject 49, testing for the Ala147Thr polymorphism has been suggested to 
predict low affinity for [11C]PBR28 in all organs, including the brain. High or Mixed 
affinity binders (Ala/Ala or Ala/Thr) will be considered eligible, whereas the Low 
affinity binders (Thr/Thr) will be considered ineligible for the research study. The MGH 
lab responsible for genotyping typically runs the genotyping assay only twice per month, 
requiring that we normally schedule screening and scanning visits approximately two 
weeks apart.  
 
An additional 10 mL of venous blood will be collected and stored for future 
investigations on the roles of genetic, molecular, and cellular factors in pain disorders. 
This will include the future possibility to generate induced pluripotent stem cells (iPSCs) 
from peripheral blood mononuclear cells51-53 to assess in-vitro alterations in patient-
derived neural or glial cells54,55.  
 
Urine drug test: We will also perform a urine test to screen for use of opioids and illicit 
drugs (including amphetamine, barbiturates, cocaine, marijuana, etc.). The urine drug 
screen will be performed during the screening visit. A rapid urine drug screening that 
utilizes monoclonal antibodies to detect elevated levels of specific drugs in urine, will be 
used for this purpose. Results will be read five minutes after the test was started.  
 
 

 
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MR-PET visits 
 
Participants eligible to continue into the study based on the screening visit and initial 
blood test will be asked to participate in a first MR-PET visit.  
 
Prior to each scan session, subjects will complete screening checklists for MRI and PET. 
These checklists will ask the patients whether they have any contraindications for MR or 
PET scanning. Female participants of childbearing age will be asked to have ~3mL of 
their blood drawn in order to perform a serum pregnancy test on the day of the scan 
(blood will be sent to the core lab for super stat testing). 
 
At the beginning of the scan session, an intravenous catheter will be placed in the 
participant’s antecubital vein of the left or right arm, prior to going to the scanning area. 
Up to 15mL of blood will be drawn to assess the levels of various substances in the 
blood, such as the proinflammatory cytokines IL-6 and TNF-alpha. Blood will be 
collected in various vials (e.g., purple top K3EDTA).  
 
Subjects will be instructed to remain still, with eyes open, for the total duration of the 
scans, except when prompted to express various ratings (e.g., pain intensity, 
unpleasantness, anxiety). The radioligand [11C]PBR28 will used to determine whether 
patients with chronic pain exhibit evidence of microglial activation.  
 
During the scan visit, subjects will be asked to complete the BPI, BDI and PROMIS-29 
assessments. 
 
Brief Pain Inventory (BPI): The BPI is a 15-item questionnaire assessing pain location, 
and 0–10 ratings of pain intensity, relief, quality, pain-related quality of life, and 
function. It has been validated in cancer and noncancer pain conditions56. 
 
Beck Depression Inventory (BDI): The 21-item BDI has shown good sensitivity and 
specificity for major depression in chronic pain patients. 
 
Patient Reported Outcomes Measurement Information System (PROMIS-29) 
questionnaire57: The PROMIS-29 is a 29-item self-report measure assessing physical, 
mental, and social health. 
 
The total duration of each scanning visit will be approximately 4 hours (and up to 6 
hours) (~45min for preparation, ~120 min for scanning procedures and ~60min for filling 
out questionnaires and observation, plus an additional ~90min to perform pregnancy test 
in women of childbearing age). In case of equipment failure (e.g., failure in 
radiosynthesis) delays of  > 2 hours may be possible. In this case, we will ask the 
participant if he or she feels comfortable with staying longer than anticipated, or will 
prefer reschedule to another date. 
 

 
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Depending on the patients’ level of discomfort and time constraints, we may occasionally 
shorten and simplify the scan visits. For instance, if the participant would feel too 
uncomfortable to lay down in the scanner for the full ~2:00 hours of scanning, we may 
administer the radioligand in the injection room and then scan the participant between 45 
and 90 minutes post-injection. 
 
The imaging visit, including all the procedures described above, will be repeated a 
second time after a 4-week trial of CBD.  
 
Drug Administration Protocol 
Following the behavioral visit, subjects will receive CBD. They will be instructed to take 
2.5mg/kg twice daily (5mg/kg/day). Participants will follow a titration schedule, with 5 
mg/kg/d in week 1, 10 mg/kg/d in week 2, 15 mg/kg/d in week 3, and 20 mg/kg/d in 
week 4. Subjects will increase to 20 mg/kg/d on the first day of the final week of the 
study (week 4) and take Epidiolex at this dose for the remainder of this final week. If 
participants report AEs (tiredness, dizziness, not tolerating the medication well), the 
physician will decrease the dose by 5 mg/kg. Participants will be treated for 4 weeks in 
total. Chronic CBD dosing up to 1500 mg/day has been reported to be tolerated well 
without AEs 58-61; minor AEs were reported after CBD use in children with epilepsy 
being treated with multiple other medications in doses up to 50 mg/kg/day62,63. 
Accordingly, we believe an upper limit of 20 mg/kg/day orally is reasonable and safe.  
 
Continuation of medication (e.g., NSAIDS) will be permitted on the condition that 
patients will be on a stable dose for at least 1 month before the baseline MR-PET scan.  
 
The Research Pharmacy at Massachusetts General Hospital will prepare the CBD. The 
study drug will be labeled as Epidiolex 100 mg/mL. It will be labeled with the name of 
the sponsor, lot number, trial subject identification number, storage conditions and the 
statement “for clinical trial use only.” Each container will be labeled with a unique 
number that will be recorded by study staff at the time of administration. As soon as 
possible after the 4-week CBD period, patients will be re-scanned and/or re-evaluated 
clinically to evaluate the hypothesis that CBD reduces glial activation and pain 
symptoms. Participants will be instructed to take CBD with food, rather than in a fasted 
state, and not to take CBD concurrently with alcohol. 
 
 
Follow-up Visits 
2-Week Visit. Patients will undergo a follow-up appointment at Week 2 with a study 
clinician, where health and adverse events will be assessed, and patients will complete 
questionnaires and will be reminded to increase medication dose. Participant may receive 
a ride to and from the study visit if requested.  
 

 
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4-Week Visit. Patients will undergo a second follow-up appointment immediately after 
the four-week treatment period with a study clinician, where we will assess back pain, 
general health, and adverse events. On the same day or as close as possible depending on 
scheduling, patients will be re-scanned, using identical protocols, to evaluate the 
hypothesis that CBD reduces glial activation. We will also repeat the questionnaires 
administered during the baseline visit to assess any changes in subjective pain. While this 
study is focused on mechanisms, and is not powered to detect a clinical effect, collecting 
pain scores will allow us to start evaluating the potential clinical significance of any 
reductions in neuroinflammation we will observe, and also provide important preliminary 
data for a subsequent clinical trial focused on efficacy. We will also take a small sample 
of blood for a follow-up liver function test. Participant may receive a ride to and from the 
study visit if requested. 
 
6-Week Call. We will conduct a follow-up call 2 weeks after the discontinuation of the 
study medication. In this call, we will assess back pain, general health and adverse 
events. 
 
 
 
DATA ACQUISITION AND ANALYSES 
 
MR-PET scanning will be performed at 3 Tesla, using Siemens TIM Trio whole-body 
MRI with head PET camera, and/or Siemens Verio whole-body MRI, whole-body PET 
camera (Biograph mMR).  
 
PET 
During each visit, [11C]PBR28 (up to 15 mCi, corresponding to ~3.7mSv) will be injected 
intravenously with a slow bolus over a 30-60s period64. This dose is compatible with a 
longitudinal study, because the total radiation of maximum ~7.4mSv received by the 
subjects participating in two scans will be significantly less than the maximum allowed 
annual whole-body dose set by the U.S. Food and Drug Administration at 5 REM, i.e., 
50mSv). The catheter will be flushed post-injection with 0.9% saline solution. Dynamic 
data will be collected over ~120 minutes in list mode, and framed post-collection. 
Regional uptake of the tracer will be estimated as SUV, SUVR, Vt and/or DVR.  
 
In addition, participants will be asked if they are willing to undergo spinal cord PET 
imaging, which will take ~20-30 minutes extra in the PET scanner at the end of the 90 
minutes post-injection. This will not add significant risk, as it will not require extra 
injection.  
 
MRI 
MRI data will be acquired simultaneously to the PET data, and may include some or all 
of these standard sequences:  BOLD fMRI (e.g., for functional connectivity analyses, to 

 
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estimate motion parameters), Diffusion-Spectrum or Diffusion-Tensor Imaging volumes 
(DSI) (to perform tractography analyses); Chemical shift imaging (to estimate brain 
metabolites); a high resolution structural volume (for anatomical reference, cortical 
reconstruction, volumetric segmentation, and attenuation correction); in addition to 
various T1 and T2 weighted structural volumes.  
 
We may collect a 6-minute resting-state connectivity functional MRI scan. The additional 
MR sequences are only collected when all the core MRI data have been completed early, 
and the patient still needs to remain in the scanner to complete data acquisition. As 
mentioned before, this is an integrated PET/MR study, the MRI (including fMRI) data is 
collected throughout the PET data acquisition, and as such the participant needs to stay in 
the scanner for the 90 minutes to complete the brain scan. Therefore these additional MR 
sequences will not affect the duration of the scan. This additional data will be used for 
ancillary analyses.  
 
Behavioral measures 
Before, during and after the scans, subjects may be asked (either verbally, or using a 
button box connected to a computer) to express various behavioral ratings, including pain 
intensity, unpleasantness, and anxiety.  
 
 
BIOSTATISTICAL ANALYSES 
 
If time allows, we may collect resting-state fMRI scans. This will only be collected if  
core MRI data have been completed early, and the patient still needs to remain in the 
scanner to complete data acquisition. Therefore, the resting state fMRI will not affect the 
duration of the scan. All fMRI data will be stored on hard drive and storage clusters. 
Behavioral data will be recorded and stored in RedCap in preparation for statistical 
analyses.  
 
In order to address our aim (‘Assess the effect of CBD on glial activation and pain), we 
will perform paired t-tests in cLBP patients before vs after receiving CBD. We will also 
perform an ANOVA including age and sex as covariates of no interest. Additionally, 
secondary regression analyses will be performed in order to evaluate the association 
between imaging and behavioral data (e.g., questionnaire scores, pain duration, etc). For 
the exploratory assessment of the relationship between imaging and pain measures, we 
will use multiple regression analysis. We will use a thalamus-targeted region of interest 
analysis, in which mean SUVRs will be extracted from the voxels within the right and 
left thalamus labels of the Harvard-Oxford Subcortical Structural Atlas and will be 
correlated with differences in clinical pain scores from baseline to Week 4. To be 
consistent in our use of non-parametric methods, we will use a non-parametric regression 
method, Generalized Additive Models. We will compute residuals adjusting for the effect 
of genotype. The Ala147Thr polymorphism in the TSPO gene predicts binding affinity 

 
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for 11C-PBR28, with the Ala/Ala, Ala/Thr and Thr/Thr genotypes being associated with 
high, mixed and low affinity binding, respectively. For all analyses, we will adjust for the 
TSPO polymorphism. 
 
Since the analysis plan requires a pre- and post-scan, we will not include patients with 
only one scan in the analysis for this pilot study. If the pilot study warrants a larger trial, 
we will use likelihood based mixed models to produce unbiased estimates of effects in the 
presence of missing data.   
 
These analyses will be performed voxelwise for the brain data, using methods similar or 
identical to those we have previously used36, as well for spinal cord data using methods 
developed by Dr. Cohen-Adad65. In addition to these voxelwise analyses, for the spinal 
cord we will perform region-of-interest (ROI) analyses focused on the spinal cord 
segments contained in the T11-L1 vertebral levels (as these contain the lower 
lumbar/upper sacral spinal cord segments).  
 
All voxelwise analyses will be conducted using the FSL suite66 for the brain, and using 
the Spinal Cord Toolbox65 for the spinal cord. Group comparisons maps will be 
thresholded using threshold-free cluster enhancement67, and a corrected threshold of 
p=0.05. All behavioral, demographic and ROI data will be analyzed using Statistica 10.0 
(StatSoft Inc., USA), and an alpha level of 0.05.  
 
Consideration of sex as a biological variable 
 In addition to the aforementioned analyses, the effect of sex will be evaluated using 
ANOVAs, because animal research suggests the presence of a possible sexual 
dimorphism in the role of glia in pain (as pain hypersensitivity may be microglial-
dependent only in males68). The effect of menstrual cycle status will also be evaluated by 
comparing women in early follicular (day 2-7 after onset of menses) and midluteal (day 
20-25 after onset of menses), based on self-report69. 
 
 
POWER ANALYSIS 
 
The purpose of this pilot study is to collect data to adequately power a placebo-
controlled trial. The sample size proposed in this study, n = 20, is similar to other 
cohorts in the PET literature. Most similar to our study is a report in Brain by Loggia et 
al that showed significant reductions in TSPO binding between 10 chronic back pain 
patients and 9 healthy controls (Loggia, 2015). This is not a fully-powered trial. If we 
see a trend toward reduction in TSPO, this will warrant a fully-powered, placebo-
controlled trial, for which an adequate sample size will be calculated.  We will have 
dual criteria by which we will consider a trend-level effect to be worthy of 
consideration of applying for funding to support a larger placebo-controlled trial.  If we 
either (1) observe a TSPO reduction in binding of 5-10% on average from post to pre-

 
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CBD, or (2) observe a clear and consistent reduction in TSPO binding in those patients 
who also report pain reductions, we will consider this a trend worth pursuit. 
 
 
RISKS AND DISCOMFORTS 
 
All subjects will undergo a telephone or email screening to attempt to distinguish 
potential subjects from those not meeting eligibility criteria. Likely candidates will 
undergo a characterization and training session, which will include a clinical screening 
procedure. This procedure will involve answering questions about subjects’ medical 
history recording of medical history review and answering questions about their medical 
situation including liver disease, kidney disease, blood disorders, heart disease, alcohol 
and opioid use, high blood pressure, asthma and other respiratory disorders. 
 
PET/MR Procedure: The U.S. Food and Drug Administration (FDA) recently gave the 
first regulatory clearance of a hybrid PET/MRI scanner in the U.S. Additionally, FDA 
considers investigations of MRI software and hardware operating within FDA specific 
parameters as non-significant risk device studies. All studies will adhere to these FDA 
approved safety levels for the Siemens system. These safety parameters include static 
magnetic field, time varying magnetic fields (dB/dt), specific absorption rate (SAR), and 
acoustic noise levels. Subjects will be informed about minimal risks of routine high 
magnetic field and non-ionizing RF radiation involved in MR imaging.  
 
 
 
 
 
Subjects will also be informed about the PET procedure and the minor risks associated 
with exposure to radiation. Subjects will also be informed about small space within the 
magnet and noises made by switching gradients. Subjects will be informed that if they 
feel uncomfortable with the study, they can choose to terminate the study at any 
time.  They will be informed that their refusal to participate in the study or choosing to 
terminate it at some point will have no effect on care and treatment received by them at 
MGH now or in future.  The subjects will be informed that their personal information will 
be protected as per the HIPAA guidelines.  
 
Intravenous catheter: An intravenous catheter will be placed for this study. The subject 
will feel a slight pinprick, similar to a bee sting, and may feel some discomfort and have 
some bruising or bleeding at the site where the needle goes in. Depending on the length 
of time the catheter is in place, a bruise may last for a day or so. Rarely an infection may 
occur at this site.  If infection does occur, it will be treated. About 24 hours after the 
beginning of the imaging procedures, we will give the subject a phone call to determine 
whether he or she is experiencing study related issues. 
 
Radiation exposure: The radiation exposure in this study will be small and there is no 
evidence that it represents a major health risk.  If subjects have participated in other 
research studies in the past 12 months that have involved radiation exposure, they will be 

 
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asked to inform the investigators or study staff (by writing initials on the consent form 
verifying that they have not been exposed to other radiation in the past 12 months).  If it 
is determined that their prior radiation exposure exceeds our current guidelines, they may 
not be allowed to participate in this study.   
 
We will use [11C]PBR28 produced by the cyclotron/radiochemistry/radiopharmacy 
facility at the A. A. Martinos Center for Biomedical Imaging. The Martinos Center has 
studied several hundreds of people with this radioligand and have had no clinically 
detectable effects or side effects. Given the use of [11C]PBR28 in a small clinical trial, we 
are in the process of requesting an IND from the FDA. 
 
The IV injection will be administered by a licensed nuclear medicine technologist. 
Should there be an adverse event, Dr. Gilman will be responsible for communicating with 
the IRB within the stipulated time frame. 
 
Imaging will be stopped should any untoward reaction be observed during the imaging 
session or if the participant so requests for whatever reason. Some subjects find it 
unpleasant or feel anxious when confined in the enclosed space of the scanner. If this 
happens, the study will be aborted. Patients will be required to use earplugs to decrease 
the noise perceived while in the scanner. 
 
EPIDIOLEX (CBD): CBD is an FDA approved medication used to treat epilepsy. 
According to the FDA briefing document on Epidiolex, dated 04/19/2018, treatment-
emergent AEs in controlled trials for Lennox-Gastaut and Dravet syndromes included 
decreased appetite, diarrhea, irritability, somnolence, fatigue, aggression, pneumonia, 
rash, and hepatic symptoms, and in a very small number of patients, an increase in 
suicidal thoughts. Of note, AE related to hepatic function were likely due to the 
interaction between CBD and anti-epileptic drugs; prescription of an anti-epileptic drug is 
an exclusionary criterion for this proposed study. Further, CBD may produce 
pharmacokinetic interaction effects when taken with opioids (Benowitz et al., 1980; 
Kotlinska-Lemieszek et al., 2015). Any subjects who at baseline had elevated AST/ALT 
levels but still met the eligibility criteria for the study will undergo a follow-up liver 
function tests at 2 weeks. In addition, we will perform a liver function test in subjects 
who at any time point during the study develop clinical signs or symptoms suggestive of 
hepatic dysfunction. 
 
Given the use of EPIDIOLEX in a small clinical trial, we are in the process of requesting 
an IND (or an IND exemption) from the FDA. 
 
Questionnaires: Minimal risks associated with completing questionnaires are subject 
fatigue and the possibility of minor psychological distress associated with answering 
sensitive questions regarding psychological functioning. Subjects will be instructed to 
complete the questionnaires to the best of their ability, but will have the option to leave 

 
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any question(s) blank. In the unlikely event that evidence of physical or psychological 
disorder is found, with the individual's permission, the information will be shared with 
his or her primary care physician who can direct care as needed.  
 
Confidentiality: As detailed, the investigators are quite careful regarding the protection 
of confidentiality, and multiple procedures are in place to reduce the likelihood of a 
breach of confidentiality. However, there is a small risk that information about subjects 
could become known to people outside of this study, and this risk is identified in the 
informed consent form. 
 
The key investigators will meet quarterly to discuss any potential adverse event and side 
effects. We will involve the MGH Human Research Committee and Radiation Safety 
Committee if any additional potential risks arise. Adverse events and unanticipated 
problems involving risks to subjects or others will be reported to the PHRC in accordance 
with PHRC adverse event and unanticipated problems reporting guidelines, as well as 
FDA when appropriate. 
 
 
POTENTIAL BENEFITS: 
 
It is unlikely that individual subjects will benefit from taking part in this study. While this 
study is powered to possibly observe a statistically significant reduction in pain due to 
CBD, it is unclear whether the effect will be clinically meaningful. However, findings 
from these studies will help advance our understanding of the pathophysiology of pain 
disorders. In particular, this project will assess the role of microglia in the establishment 
and/or maintenance of chronic pain, and how this may be affected by CBD. 
 
 
REMUNERATION: 
 
Subjects will be paid by check at the completion of the study for their participation. 
 
We will pay up to $525. Payments will be as follows: 
 
- 
$75 for the initial behavioral session (Visit 1) 
- 
$50 for completing daily surveys 
- 
$200 for each MR-PET scanning visit 
 
If during the imaging visit(s) we cannot inject the subject with the radioligand (e.g., due 
to a failure in radiosynthesis, or to issues with the scanner) he/she will receive $50. 
 
If the subject will need to stop the scan early for any reason, he/she will still receive $50 
for his/her time. Additionally, parking fees will be covered as needed.  

 
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MONITORING AND QA 
 
The proposed study will be monitored for safety, with monthly staff meetings reviewing 
adverse events and treatment outcomes and directly reporting any adverse events. The PI 
will also routinely monitor and assure the validity and integrity of collected data and 
adherence to the IRB-approved protocol. The trained staff members who carry out the 
procedures will also carefully monitor the study throughout its duration. The team will 
evaluate the progress of the study, verify that the rights and well-being of the subjects are 
protected, verify that the reported study data are accurate, complete and verifiable from 
source documents, and the conduct of the study is in compliance with the approved 
protocol and amendments. Outcome monitoring and adverse events will all be reported 
through appropriate channels of the Human Studies Committee as well to the FDA when 
appropriate. 
 
If a patient develops clinical signs or symptoms suggestive of hepatic dysfunction (e.g., 
unexplained nausea, vomiting, right upper quadrant abdominal pain, fatigue, anorexia, or 
jaundice and/or dark urine), we will promptly measure serum transaminases and total 
bilirubin and interrupt or discontinue treatment with EPIDIOLEX, as appropriate. We 
will discontinue EPIDIOLEX in any patients with elevations of transaminase levels 
greater than 3 times the ULN and bilirubin levels greater than 2 times the ULN. Our 
physician monitoring group (Drs. Mao, Zhang, Schnitzer, and Evins) will consider 
stopping the study if back pain becomes significantly worse in 3 or more patients. If 
serum liver enzyme concentrations are significantly elevated (with elevations of 
transaminase levels greater than 3 times the ULN and bilirubin levels greater than 2 times 
the ULN) in 2 or more patients, which will be considered serious adverse events, the 
study will be stopped.  In addition, if two or more patients experience any serious adverse 
event, the study will be stopped. 
 
The Siemens MR-PET scanners have a built-in self-monitoring system that automatically 
shuts off if parameters exceed safe levels.  For backup protection NMR technicians 
constantly monitor the subjects’ physiological signs and the quality of the raw data. 
 
Quality assurance of the scanner’s performance is obtained by a daily quality assurance 
protocol.  More extensive quality assurance protocols are performed monthly under the 
commercial service contract with Siemens Medical Systems.  The daily quality assurance 
protocol consists of an image Signal-to-Noise measurement in a phantom and a stability 
run which checks the image-to-image variation in image intensity over 600 images using 
a standard echoplanar imaging sequence with a head-sized phantom.  The images are 
analyzed by the technologist to provide data on SNR (as an absolute, unitless number) 

 
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and stability expressed as the peak-to-peak variation in the mean of a 15x15 pixel region 
of interest (ROI) in the center of the phantom expressed as a percentage of the mean of 
the ROI.  Runs are performed at each of 3 TR values (300ms, 800ms, 1300ms).  The time 
course of the means is also reviewed to check for periodicities (the TR values are chosen 
so as not to be multiples of one another).  If the peak-to-peak variation is greater than 
0.5% of the mean value, the Siemens Medical System service engineer is called.   In 
addition to these daily quality assurance tests, the Siemens Medical System service 
engineer performs quality assurance tests once a month.  These tests include a SNR test, a 
small sample stability test, a gradient stability test, a gradient eddy current test, a shim 
test, an image uniformity test, and an RF stability test. 
 

 
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