A phase I, randomized, double-blinded, placebo-controlled, single ascending dose study to investigate the safety, local tolerability and transformation of nucleus pulposus following intradiscal injection of STA363 or placebo in patients with discogenic low back pain.

15 patients will participate in either of 3 dose groups, each comprising 5 patients:

• Group 1: STA363 dose 1 (3 patients) or placebo (2 patients)
• Group 2: STA363 dose 2 (3 patients) or placebo (2 patients)
• Group 3: STA363 dose 3 (3 patients) or placebo (2 patients)

Inclusion Criteria:

• Signed informed consent prior to any study-related procedures
• Chronic discogenic low back pain present for more than 6 months prior to the screening visit
• 20 to 60 years of age at the screening visit
• Insufficient response to at least 6 months of non-operative treatment (analgesics and/or antiinflammatory medication, physiotherapy etc.)
• A single lumbar disc appropriate for treatment at L3/4 to L5/S1, based on clinical evaluation by the investigator
• Pfirrmann grade II-III
• Ability to understand the written and verbal information about the study

Exclusion Criteria:

• Treatment with any investigational product within 3 months prior to the screening visit
• More than one painful intervertebral disc
• A painful intervertebral disc above L3/4 level
• Current infection or prior history of spinal infection (e.g., discitis, septic arthritis, epidural abscess) or an active systemic infection
• Previous lumbar spine surgery
• Previous disc invasive treatment procedures at the affected level(s) (e.g., intradiscal electrothermal therapy, intradiscal radiofrequency thermocoagulation)
• Pfirrmann grade I, IV and V
• Evidence of prior lumbar vertebral body fracture or trauma
• Need for spinal decompression assessed by the investigator
• Presence of disc extrusion or sequestration
• Patients previously included in the study
• Patients suffering from psychosomatic pain in the opinion of the investigator
• Referred leg pain of compressive origin
• Known alcohol and/or drug abuse
• Severe intercurrent illness (e.g. rheumatic disease or chronic pain syndrome) or concomitant treatment (e.g. immunosuppressive drugs), which, in the opinion of the investigator, may put the patient at risk when participating in the study, or affect the patient's ability to take part in the study
• Clinically significant abnormalities in clinical chemistry or haematology parameters as assessed by the investigator
• Pregnant or lactating females or intention to become pregnant within the study period
• Known allergy to any of the components of the drug product or placebo
• Known opioid allergy or intolerance
• Patients requiring treatment with warfarin or other anticoagulant therapy
• Unwillingness to refrain from treatment with non-steroidal anti-inflammatory drugs (NSAIDs) within 5 days before the planned study treatment
• Body weight less than 50 kg