Sponsor's strategic decision not related to safety concerns.

The primary objective of the study is to assess the overall efficacy of a single intervertebral local administration of AGA111 in patients with degenerative disc disease undergoing lumbar interbody fusion.

This is a phase 3, randomized, double-blind, placebo-controlled study to evaluate the efficacy and safety of a single intervertebral local administration of AGA111 in patients with degenerative disc disease undergoing lumbar interbody fusion. About 400 subjects who meet the eligibility criteria will be randomly assigned to the following two treatment groups in a 1:1 ratio.

Inclusion Criteria:

1. Has degenerative disc disease of L3-S1 with low back pain, with or without a history of radiating leg or buttock pain, paresthesia, numbness or weakness secondary to radiculopathy of the corresponding spinal segment;
2. Has radiographic evidence (e.g., X-ray and CT/magnetic resonance imaging MRI) of degenerative disc disease;
3. Adults ≥ 18 and ≤ 80 years of age and skeletally mature at the time of surgery;
4. Plan to undergo a single-level lumbar interbody fusion;
5. Preoperative ODI score ≥ 30;
6. Has not respond to conservative treatment (e.g, bed rest, physical therapy, drugs, local injections, manipulation and other non-surgical treatments) for a period of at least 3 months;
7. Willing and able to comply with the protocol and able to understand and sign the subject's informed consent form (ICF) ;
8. Female subjects of child-bearing potential must agree to use a highly effective method of birth control during the study and for 1 year after the administration of investigational drug, and must have a negative pregnancy test prior to the randomization.

Exclusion Criteria:

1. Has undergone other decompression, fusion, and/or other non-fusion spinal surgery at the spinal segment intended to undergo the surgery prior to the screening (except for transforaminal endoscopic discectomy);
2. Known other significant lumbar instability;
3. Lumbar scoliosis > 30 degrees (evaluated by investigators);
4. Presence of active malignancy or prior history of malignancy;
5. Overt or active infection, either local to surgical space or systemic;
6. Patients with a dual-energy X-ray absorption (DXA) total hip T-score ≤ -3.0;
7. Body weight index (BMI) <18.5 kg/m2 or BMI > 35 kg/m2;
8. Have received other treatments affecting fusion surgery, such as radiotherapy near the surgical site;
9. Presence of other co-morbidities of the spine or upper/lower extremities that may affect the investigator's assessment of the lumbosacral nervous system and/or pain;
10. Presence of mental disease or psychiatric condition that interferes with the patient's self-assessment of function, pain, or quality of life;
11. History of progressive osseous heteroplasia or fibrodysplasia ossificans progressiva;
12. Known hypersensitivity or allergy to bone morphogenetic protein (BMP) products or their excipient; and/or instrumentation materials in surgery, e.g., titanium, titanium alloy, cobalt chrome, cobalt chrome alloy, or polyetheretherketone (PEEK);
13. Pregnant or lactating women; or plan to become pregnant within 1 year following the study surgery.
14. Other conditions that, in the opinion of the investigator, would interfere with the subject's ability to comply with the protocol, and other conditions that will make the subject inappropriate for participation in the study as judged by the investigator.