Trial Outcomes & Findings for Evaluating the Role of Neuroinflammation in Low Back Pain (NCT NCT03106740)

Last Updated: 2025-05-11

Results Overview

The ratio of the standardized uptake value (SUV; mean radioactivity divided by the injected dose by weight) of the whole thalamus divided by the SUV of the whole brain (i.e., standardized uptake value ratio or SUVR) derived from the translocator protein positron emission tomography (TSPO-PET) signal. Higher SUVR might be indicative of higher neuroinflammation.

Recruitment status

COMPLETED

Study phase

PHASE2

Target enrollment

60 participants

Primary outcome timeframe

The outcome measure was assessed in two time points, before and after a two-week treatment period.

Results posted on

2025-05-11

Participant Flow

Participant milestones

Participant milestones
Measure	Minocycline Arm Evaluation with Magnetic Resonance-Positron Emission Tomography Imaging and/or behavioral pain assessment before and after a 2-week trial of Minocycline Hydrochloride, 100mg capsule. Minocycline Hydrochloride 100mg Capsule: Minocycline administered by mouth daily for 2 weeks Magnetic Resonance-Positron Emission Tomography Imaging: Up to 15 millicuries of \[11C\]PBR28 administered to each subject at each imaging visit, for a maximum of 2 imaging visits.	Placebo Arm Evaluation with Magnetic Resonance-Positron Emission Tomography Imaging and/or behavioral pain assessment before and after 2 weeks of treatment with a placebo capsule. Placebo Capsule: Placebo (lactose powder) administered by mouth daily for 2 weeks. Magnetic Resonance-Positron Emission Tomography Imaging: Up to 15 millicuries of \[11C\]PBR28 administered to each subject at each imaging visit, for a maximum of 2 imaging visits.
Overall Study STARTED	30	30
Overall Study COMPLETED	25	23
Overall Study NOT COMPLETED	5	7

Reasons for withdrawal

Reasons for withdrawal
Measure	Minocycline Arm Evaluation with Magnetic Resonance-Positron Emission Tomography Imaging and/or behavioral pain assessment before and after a 2-week trial of Minocycline Hydrochloride, 100mg capsule. Minocycline Hydrochloride 100mg Capsule: Minocycline administered by mouth daily for 2 weeks Magnetic Resonance-Positron Emission Tomography Imaging: Up to 15 millicuries of \[11C\]PBR28 administered to each subject at each imaging visit, for a maximum of 2 imaging visits.	Placebo Arm Evaluation with Magnetic Resonance-Positron Emission Tomography Imaging and/or behavioral pain assessment before and after 2 weeks of treatment with a placebo capsule. Placebo Capsule: Placebo (lactose powder) administered by mouth daily for 2 weeks. Magnetic Resonance-Positron Emission Tomography Imaging: Up to 15 millicuries of \[11C\]PBR28 administered to each subject at each imaging visit, for a maximum of 2 imaging visits.
Overall Study Lost to Follow-up	2	2
Overall Study Withdrawal by Subject	2	4
Overall Study Physician Decision	0	1
Overall Study Partial data	1	0

Baseline Characteristics

Evaluating the Role of Neuroinflammation in Low Back Pain

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	Minocycline Arm n=25 Participants Evaluation with Magnetic Resonance-Positron Emission Tomography Imaging and/or behavioral pain assessment before and after a 2-week trial of Minocycline Hydrochloride, 100mg capsule. Minocycline Hydrochloride 100mg Capsule: Minocycline administered by mouth daily for 2 weeks Magnetic Resonance-Positron Emission Tomography Imaging: Up to 15 millicuries of \[11C\]PBR28 administered to each subject at each imaging visit, for a maximum of 2 imaging visits.	Placebo Arm n=23 Participants Evaluation with Magnetic Resonance-Positron Emission Tomography Imaging and/or behavioral pain assessment before and after 2 weeks of treatment with a placebo capsule. Placebo Capsule: Placebo (lactose powder) administered by mouth daily for 2 weeks. Magnetic Resonance-Positron Emission Tomography Imaging: Up to 15 millicuries of \[11C\]PBR28 administered to each subject at each imaging visit, for a maximum of 2 imaging visits.	Total n=48 Participants Total of all reporting groups
Age, Continuous	44.6 Years STANDARD_DEVIATION 16.9 • n=5 Participants	49 Years STANDARD_DEVIATION 17.1 • n=7 Participants	45.9 Years STANDARD_DEVIATION 16.1 • n=5 Participants
Sex: Female, Male Female	16 Participants n=5 Participants	14 Participants n=7 Participants	30 Participants n=5 Participants
Sex: Female, Male Male	9 Participants n=5 Participants	9 Participants n=7 Participants	18 Participants n=5 Participants
Race (NIH/OMB) American Indian or Alaska Native	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants
Race (NIH/OMB) Asian	2 Participants n=5 Participants	3 Participants n=7 Participants	5 Participants n=5 Participants
Race (NIH/OMB) Native Hawaiian or Other Pacific Islander	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants
Race (NIH/OMB) Black or African American	2 Participants n=5 Participants	1 Participants n=7 Participants	3 Participants n=5 Participants
Race (NIH/OMB) White	19 Participants n=5 Participants	18 Participants n=7 Participants	37 Participants n=5 Participants
Race (NIH/OMB) More than one race	1 Participants n=5 Participants	1 Participants n=7 Participants	2 Participants n=5 Participants
Race (NIH/OMB) Unknown or Not Reported	1 Participants n=5 Participants	0 Participants n=7 Participants	1 Participants n=5 Participants
Region of Enrollment United States	25 participants n=5 Participants	23 participants n=7 Participants	48 participants n=5 Participants
Genotype GG	16 Participants n=5 Participants	14 Participants n=7 Participants	30 Participants n=5 Participants
Genotype GA	9 Participants n=5 Participants	9 Participants n=7 Participants	18 Participants n=5 Participants

PRIMARY outcome

Timeframe: The outcome measure was assessed in two time points, before and after a two-week treatment period.

Outcome measures

Outcome measures
Measure	Minocycline Arm n=25 Participants Evaluation with Magnetic Resonance-Positron Emission Tomography Imaging and/or behavioral pain assessment before and after a 2-week trial of Minocycline Hydrochloride, 100mg capsule. Minocycline Hydrochloride 100mg Capsule: Minocycline administered by mouth daily for 2 weeks Magnetic Resonance-Positron Emission Tomography Imaging: Up to 15 millicuries of \[11C\]PBR28 administered to each subject at each imaging visit, for a maximum of 2 imaging visits.	Placebo Arm n=23 Participants Evaluation with Magnetic Resonance-Positron Emission Tomography Imaging and/or behavioral pain assessment before and after 2 weeks of treatment with a placebo capsule. Placebo Capsule: Placebo (lactose powder) administered by mouth daily for 2 weeks. Magnetic Resonance-Positron Emission Tomography Imaging: Up to 15 millicuries of \[11C\]PBR28 administered to each subject at each imaging visit, for a maximum of 2 imaging visits.
Changes in Thalamic Standardized Uptake Value Ratio (SUVR) - Pre-treatment Thalamic SUVR	1.188 Standardized uptake value ratio Standard Deviation 0.051	1.166 Standardized uptake value ratio Standard Deviation 0.056
Changes in Thalamic Standardized Uptake Value Ratio (SUVR) - Post-treatment Thalamic SUVR	1.189 Standardized uptake value ratio Standard Deviation 0.045	1.165 Standardized uptake value ratio Standard Deviation 0.054

SECONDARY outcome

Timeframe: 2 weeks

The investigators will test for the presence of a significant treatment\*time interaction in the spinal \[11C\]PBR28 signal.

Outcome measures

Outcome data not reported

SECONDARY outcome

Timeframe: 2 weeks

The investigators will test for the presence of a significant treatment\*time interaction in pain outcomes using the severity subscale of the Brief Pain Intensity, short form (range 0-10)

Outcome measures

Outcome data not reported

Adverse Events

Minocycline Arm

Serious events: 1 serious events

Other events: 9 other events

Deaths: 0 deaths

Placebo Arm

Serious events: 0 serious events

Other events: 15 other events

Deaths: 0 deaths

Serious adverse events

Serious adverse events
Measure	Minocycline Arm n=30 participants at risk Evaluation with Magnetic Resonance-Positron Emission Tomography Imaging and/or behavioral pain assessment before and after a 2-week trial of Minocycline Hydrochloride, 100mg capsule. Minocycline Hydrochloride 100mg Capsule: Minocycline administered by mouth daily for 2 weeks Magnetic Resonance-Positron Emission Tomography Imaging: Up to 15 millicuries of \[11C\]PBR28 administered to each subject at each imaging visit, for a maximum of 2 imaging visits.	Placebo Arm n=30 participants at risk Evaluation with Magnetic Resonance-Positron Emission Tomography Imaging and/or behavioral pain assessment before and after 2 weeks of treatment with a placebo capsule. Placebo Capsule: Placebo (lactose powder) administered by mouth daily for 2 weeks. Magnetic Resonance-Positron Emission Tomography Imaging: Up to 15 millicuries of \[11C\]PBR28 administered to each subject at each imaging visit, for a maximum of 2 imaging visits.
Nervous system disorders Stroke	3.3% 1/30 • Number of events 1 • Between 14 and 43 days from the pre-treatment scan. Any untoward or unfavorable medical occurrence in a participant, including any abnormal sign (for example, abnormal physical exam or laboratory finding), symptom, or disease, temporally associated with the participant's participation in the research, whether or not considered related to the participant's participation in the research. Three types of adverse event data are to be reported: "All-Cause Mortality," "Serious," and "Other (Not Including Serious)" Adverse Events.	0.00% 0/30 • Between 14 and 43 days from the pre-treatment scan. Any untoward or unfavorable medical occurrence in a participant, including any abnormal sign (for example, abnormal physical exam or laboratory finding), symptom, or disease, temporally associated with the participant's participation in the research, whether or not considered related to the participant's participation in the research. Three types of adverse event data are to be reported: "All-Cause Mortality," "Serious," and "Other (Not Including Serious)" Adverse Events.

Other adverse events

Other adverse events
Measure	Minocycline Arm n=30 participants at risk Evaluation with Magnetic Resonance-Positron Emission Tomography Imaging and/or behavioral pain assessment before and after a 2-week trial of Minocycline Hydrochloride, 100mg capsule. Minocycline Hydrochloride 100mg Capsule: Minocycline administered by mouth daily for 2 weeks Magnetic Resonance-Positron Emission Tomography Imaging: Up to 15 millicuries of \[11C\]PBR28 administered to each subject at each imaging visit, for a maximum of 2 imaging visits.	Placebo Arm n=30 participants at risk Evaluation with Magnetic Resonance-Positron Emission Tomography Imaging and/or behavioral pain assessment before and after 2 weeks of treatment with a placebo capsule. Placebo Capsule: Placebo (lactose powder) administered by mouth daily for 2 weeks. Magnetic Resonance-Positron Emission Tomography Imaging: Up to 15 millicuries of \[11C\]PBR28 administered to each subject at each imaging visit, for a maximum of 2 imaging visits.
Injury, poisoning and procedural complications Ecchymosis	13.3% 4/30 • Number of events 4 • Between 14 and 43 days from the pre-treatment scan. Any untoward or unfavorable medical occurrence in a participant, including any abnormal sign (for example, abnormal physical exam or laboratory finding), symptom, or disease, temporally associated with the participant's participation in the research, whether or not considered related to the participant's participation in the research. Three types of adverse event data are to be reported: "All-Cause Mortality," "Serious," and "Other (Not Including Serious)" Adverse Events.	20.0% 6/30 • Number of events 6 • Between 14 and 43 days from the pre-treatment scan. Any untoward or unfavorable medical occurrence in a participant, including any abnormal sign (for example, abnormal physical exam or laboratory finding), symptom, or disease, temporally associated with the participant's participation in the research, whether or not considered related to the participant's participation in the research. Three types of adverse event data are to be reported: "All-Cause Mortality," "Serious," and "Other (Not Including Serious)" Adverse Events.
Injury, poisoning and procedural complications Vasovagal syncope	3.3% 1/30 • Number of events 1 • Between 14 and 43 days from the pre-treatment scan. Any untoward or unfavorable medical occurrence in a participant, including any abnormal sign (for example, abnormal physical exam or laboratory finding), symptom, or disease, temporally associated with the participant's participation in the research, whether or not considered related to the participant's participation in the research. Three types of adverse event data are to be reported: "All-Cause Mortality," "Serious," and "Other (Not Including Serious)" Adverse Events.	3.3% 1/30 • Number of events 1 • Between 14 and 43 days from the pre-treatment scan. Any untoward or unfavorable medical occurrence in a participant, including any abnormal sign (for example, abnormal physical exam or laboratory finding), symptom, or disease, temporally associated with the participant's participation in the research, whether or not considered related to the participant's participation in the research. Three types of adverse event data are to be reported: "All-Cause Mortality," "Serious," and "Other (Not Including Serious)" Adverse Events.
Injury, poisoning and procedural complications Claustrophobia	0.00% 0/30 • Between 14 and 43 days from the pre-treatment scan. Any untoward or unfavorable medical occurrence in a participant, including any abnormal sign (for example, abnormal physical exam or laboratory finding), symptom, or disease, temporally associated with the participant's participation in the research, whether or not considered related to the participant's participation in the research. Three types of adverse event data are to be reported: "All-Cause Mortality," "Serious," and "Other (Not Including Serious)" Adverse Events.	6.7% 2/30 • Number of events 2 • Between 14 and 43 days from the pre-treatment scan. Any untoward or unfavorable medical occurrence in a participant, including any abnormal sign (for example, abnormal physical exam or laboratory finding), symptom, or disease, temporally associated with the participant's participation in the research, whether or not considered related to the participant's participation in the research. Three types of adverse event data are to be reported: "All-Cause Mortality," "Serious," and "Other (Not Including Serious)" Adverse Events.
Injury, poisoning and procedural complications Discomfort	13.3% 4/30 • Number of events 4 • Between 14 and 43 days from the pre-treatment scan. Any untoward or unfavorable medical occurrence in a participant, including any abnormal sign (for example, abnormal physical exam or laboratory finding), symptom, or disease, temporally associated with the participant's participation in the research, whether or not considered related to the participant's participation in the research. Three types of adverse event data are to be reported: "All-Cause Mortality," "Serious," and "Other (Not Including Serious)" Adverse Events.	10.0% 3/30 • Number of events 3 • Between 14 and 43 days from the pre-treatment scan. Any untoward or unfavorable medical occurrence in a participant, including any abnormal sign (for example, abnormal physical exam or laboratory finding), symptom, or disease, temporally associated with the participant's participation in the research, whether or not considered related to the participant's participation in the research. Three types of adverse event data are to be reported: "All-Cause Mortality," "Serious," and "Other (Not Including Serious)" Adverse Events.
Gastrointestinal disorders Gastrointestinal discomfort	0.00% 0/30 • Between 14 and 43 days from the pre-treatment scan. Any untoward or unfavorable medical occurrence in a participant, including any abnormal sign (for example, abnormal physical exam or laboratory finding), symptom, or disease, temporally associated with the participant's participation in the research, whether or not considered related to the participant's participation in the research. Three types of adverse event data are to be reported: "All-Cause Mortality," "Serious," and "Other (Not Including Serious)" Adverse Events.	10.0% 3/30 • Number of events 3 • Between 14 and 43 days from the pre-treatment scan. Any untoward or unfavorable medical occurrence in a participant, including any abnormal sign (for example, abnormal physical exam or laboratory finding), symptom, or disease, temporally associated with the participant's participation in the research, whether or not considered related to the participant's participation in the research. Three types of adverse event data are to be reported: "All-Cause Mortality," "Serious," and "Other (Not Including Serious)" Adverse Events.
Skin and subcutaneous tissue disorders Rash	0.00% 0/30 • Between 14 and 43 days from the pre-treatment scan. Any untoward or unfavorable medical occurrence in a participant, including any abnormal sign (for example, abnormal physical exam or laboratory finding), symptom, or disease, temporally associated with the participant's participation in the research, whether or not considered related to the participant's participation in the research. Three types of adverse event data are to be reported: "All-Cause Mortality," "Serious," and "Other (Not Including Serious)" Adverse Events.	3.3% 1/30 • Number of events 1 • Between 14 and 43 days from the pre-treatment scan. Any untoward or unfavorable medical occurrence in a participant, including any abnormal sign (for example, abnormal physical exam or laboratory finding), symptom, or disease, temporally associated with the participant's participation in the research, whether or not considered related to the participant's participation in the research. Three types of adverse event data are to be reported: "All-Cause Mortality," "Serious," and "Other (Not Including Serious)" Adverse Events.
Infections and infestations COVID-19 infection	10.0% 3/30 • Number of events 3 • Between 14 and 43 days from the pre-treatment scan. Any untoward or unfavorable medical occurrence in a participant, including any abnormal sign (for example, abnormal physical exam or laboratory finding), symptom, or disease, temporally associated with the participant's participation in the research, whether or not considered related to the participant's participation in the research. Three types of adverse event data are to be reported: "All-Cause Mortality," "Serious," and "Other (Not Including Serious)" Adverse Events.	3.3% 1/30 • Number of events 1 • Between 14 and 43 days from the pre-treatment scan. Any untoward or unfavorable medical occurrence in a participant, including any abnormal sign (for example, abnormal physical exam or laboratory finding), symptom, or disease, temporally associated with the participant's participation in the research, whether or not considered related to the participant's participation in the research. Three types of adverse event data are to be reported: "All-Cause Mortality," "Serious," and "Other (Not Including Serious)" Adverse Events.
Infections and infestations Shingles	0.00% 0/30 • Between 14 and 43 days from the pre-treatment scan. Any untoward or unfavorable medical occurrence in a participant, including any abnormal sign (for example, abnormal physical exam or laboratory finding), symptom, or disease, temporally associated with the participant's participation in the research, whether or not considered related to the participant's participation in the research. Three types of adverse event data are to be reported: "All-Cause Mortality," "Serious," and "Other (Not Including Serious)" Adverse Events.	3.3% 1/30 • Number of events 1 • Between 14 and 43 days from the pre-treatment scan. Any untoward or unfavorable medical occurrence in a participant, including any abnormal sign (for example, abnormal physical exam or laboratory finding), symptom, or disease, temporally associated with the participant's participation in the research, whether or not considered related to the participant's participation in the research. Three types of adverse event data are to be reported: "All-Cause Mortality," "Serious," and "Other (Not Including Serious)" Adverse Events.
Musculoskeletal and connective tissue disorders Pain	0.00% 0/30 • Between 14 and 43 days from the pre-treatment scan. Any untoward or unfavorable medical occurrence in a participant, including any abnormal sign (for example, abnormal physical exam or laboratory finding), symptom, or disease, temporally associated with the participant's participation in the research, whether or not considered related to the participant's participation in the research. Three types of adverse event data are to be reported: "All-Cause Mortality," "Serious," and "Other (Not Including Serious)" Adverse Events.	3.3% 1/30 • Number of events 1 • Between 14 and 43 days from the pre-treatment scan. Any untoward or unfavorable medical occurrence in a participant, including any abnormal sign (for example, abnormal physical exam or laboratory finding), symptom, or disease, temporally associated with the participant's participation in the research, whether or not considered related to the participant's participation in the research. Three types of adverse event data are to be reported: "All-Cause Mortality," "Serious," and "Other (Not Including Serious)" Adverse Events.
Neoplasms benign, malignant and unspecified (incl cysts and polyps) Skin cancer removal	3.3% 1/30 • Number of events 1 • Between 14 and 43 days from the pre-treatment scan. Any untoward or unfavorable medical occurrence in a participant, including any abnormal sign (for example, abnormal physical exam or laboratory finding), symptom, or disease, temporally associated with the participant's participation in the research, whether or not considered related to the participant's participation in the research. Three types of adverse event data are to be reported: "All-Cause Mortality," "Serious," and "Other (Not Including Serious)" Adverse Events.	0.00% 0/30 • Between 14 and 43 days from the pre-treatment scan. Any untoward or unfavorable medical occurrence in a participant, including any abnormal sign (for example, abnormal physical exam or laboratory finding), symptom, or disease, temporally associated with the participant's participation in the research, whether or not considered related to the participant's participation in the research. Three types of adverse event data are to be reported: "All-Cause Mortality," "Serious," and "Other (Not Including Serious)" Adverse Events.

Additional Information

Marco Loggia

Massachusetts General Hospital

Phone: (617) 643-7267

Email: [email protected]

Results disclosure agreements

Principal investigator is a sponsor employee
Publication restrictions are in place