This is a Phase 2a safety and efficacy study of XT-150 in adult participants experiencing back pain due to inflammation of the facet joint, also known as facet joint osteoarthritis (FJOA), and who are eligible for intra articular glucocorticoid injection, or radiofrequency ablation of medial branches of the primary dorsal ramus of the exiting nerve root, which innervates the adjacent facet joints.

Study drug will be administered at Day 0 and Day 90 by bilateral intra-articular (IA) injection into the facet capsule, at the affected spinal level (e.g. Lumbar [L]3-4, L4-5, or L5-Sacrum [S]1) as determined by imaging (e.g., Magnetic resonance imaging [MRI], Computed tomography [CT]), X-ray, etc.) and physical exam.

Up to 72 participants will be randomized to placebo or one of two dose treatment groups (24 participants per treatment group).

1. 0.15 mg XT-150 (1.0 milliliter [mL] total delivered by two 0.5 mL injections)
2. 0.45 mg XT-150 (1.0 mL total delivered by two 0.5 mL injections)
3. Placebo (Sterile saline) (1.0 mL total delivered by two 0.5 mL injections)

Inclusion Criteria:

Participants are required to meet ALL of the following inclusion criteria:

1. Male or female, between 18 and 90 years of age, inclusive.
2. Sufficiently severe facet arthropathy of lumbar facets as determined by imaging (e.g., MRI, CT, X-ray, etc.) to establish an underlying basis of disease, as determined by usual bony and ligamentous signs of osteoarthritis (OA). Use of historical images permitted if obtained within the last 12 months.
3. Complaint of nociceptive, mechanical pain of lumbar spine, in particular pain localized to paramedian axis as opposed to midline or radicular. Radicular pain as a secondary finding may be allowed if it is in addition to mechanical pain and can be clinically distinguished by participant.
4. LBP (Low Back Pain) worsened by activity or motion of region
5. Have had a positive diagnostic facet pain block with lidocaine; admittance if participant gains 50% relief of pain within 30 minutes of test injection
6. Be free of local or intra-articular infection, tumor or other causes of localized LBP, for example, spondylolysis/pars defect, and adjacent vertebral body compression fracture based on imaging evaluation.
7. Symptomatic disease because of osteoarthritis, established by imaging of facet joint and defined as a worst pain of at least 50 at the Screening Visit and the Baseline (Day 0) Visit (based on scale of 0 to 100, with 100 representing "pain as bad as you can imagine") using Visual Analog Scale (VAS).
8. Stable analgesic regimen during the 4 weeks prior to enrollment. Participants who are not currently on any analgesics at the time of enrollment because they have discontinued prior analgesic therapy due to intolerance or lack of effect may be included. New analgesics or changes to the pre-established regimen during the study, with the exception of rescue medication use, are not permitted.
9. Inadequate pain relief with prior therapies lasting 3 months or more.
10. In the judgment of the Investigator, acceptable general medical condition
11. Heterosexually active participants, male and female who are not surgically sterile or post-menopausal, must agree to use effective contraception, including abstinence, for the duration of the study and for 3 months after the study is completed
12. Have suitable facet joint anatomy for intra-articular injection
13. Willing and able to return for the follow-up (FU) visits
14. Able to read and understand study instructions, and willing and able to comply with all study procedures

Exclusion Criteria:

Participants must NOT meet any of the following exclusion criteria:

1. Hypersensitivity, allergy, or significant reaction to lidocaine or any ingredient of the study drug, including double-stranded DNA, mannose, and sucrose
2. Facet injection with corticosteroid in the past 6 months
3. Lumbar medial branch nerve ablation (e.g., by radiofrequency technique) within the past 12 months
4. Prior lumbar fusion surgery
5. Prior or existing medial branch nerve stimulation device (e.g., Mainstay device)
6. Scheduled surgical procedure or nerve ablation to joint within the next 6 months; participant agrees not to schedule a surgical procedure, nerve ablation, or added facet injection within 6 months of study treatment
7. High peri-operative risks which in the judgment of the investigator preclude a safe facet joint injection procedure (e.g. extreme obesity putting injection accuracy at risk, etc.)
8. Current treatment with immunosuppressive (systemic corticosteroid therapy [equivalent to >10 milligrams per day {mg/day} prednisone] or other strong immunosuppressant)
9. History of immunosuppressive therapy; high-potency systemic steroids in the last 3 months.
10. Currently receiving systemic chemotherapy or radiation therapy for malignancy
11. Clinically significant hepatic disease as indicated by clinical laboratory results ≥3 times the upper limit of normal for any liver function test (e.g., aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase)
12. Severe anemia (Grade 3; hemoglobin <8.0 grams per deciliter [g/dL], <4.9 millimoles per liter [mmol/L], <80 g/L; transfusion indicated), Grade 1 white cell counts (lymphocytes \

Adverse events were collected from the time of informed consent through the last study visit on Day 270 (9 months). Treatment Emergent Adverse Events occurred from the time of study drug treatment on Day 0 through end of study (Day 270) or early termination.

Placebo controlled, double blind