• Change from baseline to week 12 in the WOMAC total score (based on the full survey) in patients treated with REGN5069 compared to patients treated with placebo [ Time Frame: Baseline to week 12 ]
  The WOMAC measures five items for pain (score range 0-20), two for stiffness (score range 0-8), and 17 for functional limitation (score range 0-68)
• Change from baseline to week 12 in the WOMAC physical function subscale score in patients treated with REGN5069 compared to patients treated with placebo [ Time Frame: Baseline to week 12 ]
  The WOMAC measures five items for pain (score range 0-20), two for stiffness (score range 0-8), and 17 for functional limitation (score range 0-68)
• Change from baseline to week 12 in the Patient Global Assessment score in patients treated with REGN5069 compared to patients treated with placebo [ Time Frame: Baseline to week 12 ]
  The Patient Global Assessment of OA is a patient-rated assessment of current disease state on a 5-point Likert scale (1 = very good; 2 = good; 3 = fair; 4 = poor; and 5 = very poor)
• Change from baseline to week 12 in WOMAC stiffness subscale score in patients treated with REGN5069 compared to patients treated with placebo [ Time Frame: Baseline to week 12 ]
  The WOMAC measures five items for pain (score range 0-20), two for stiffness (score range 0-8), and 17 for functional limitation (score range 0-68)
• Percentage of patients treated with REGN5069, compared to that of patients treated with placebo, who had a response at week 12, with response defined as an improvement by ≥30% in the WOMAC pain subscale scores [ Time Frame: Baseline to week 12 ]
  The WOMAC measures five items for pain (score range 0-20), two for stiffness (score range 0-8), and 17 for functional limitation (score range 0-68)
• Incidence of treatment-emergent adverse events (TEAEs) in patients treated with REGN5069 compared to patients treated with placebo [ Time Frame: Through the study duration (52 weeks) ]
• Incidence of imaging abnormalities consistent with accelerated arthropathies as assessed by X-ray and MRI in patients treated with REGN5069 compared to patients treated with placebo [ Time Frame: Through the study duration (52 weeks) ]
• Presence of anti-REGN5069 antibody development in patients treated with REGN5069 compared to patients treated with placebo [ Time Frame: Through the study duration (52 weeks) ]

• Change from baseline to week 12 in the WOMAC total score (based on the full survey) in patients treated with REGN5069 compared to patients treated with placebo [ Time Frame: Baseline to week 12 ]
  The WOMAC measures five items for pain (score range 0-20), two for stiffness (score range 0-8), and 17 for functional limitation (score range 0-68)
• Change from baseline to week 12 in the WOMAC physical function subscale score in patients treated with REGN5069 compared to patients treated with placebo [ Time Frame: Baseline to week 12 ]
  The WOMAC measures five items for pain (score range 0-20), two for stiffness (score range 0-8), and 17 for functional limitation (score range 0-68)
• Change from baseline to week 12 in the Patient Global Assessment score in patients treated with REGN5069 compared to patients treated with placebo [ Time Frame: Baseline to week 12 ]
  The Patient Global Assessment of OA is a patient-rated assessment of current disease state on a 5-point Likert scale (1 = very good; 2 = good; 3 = fair; 4 = poor; and 5 = very poor)
• Change from baseline to week 12 in WOMAC stiffness subscale score in patients treated with REGN5069 compared to patients treated with placebo [ Time Frame: Baseline to week 12 ]
  The WOMAC measures five items for pain (score range 0-20), two for stiffness (score range 0-8), and 17 for functional limitation (score range 0-68)
• Percentage of patients treated with REGN5069, compared to that of patients treated with placebo, who had a response at week 12, with response defined as an improvement by ≥30% in the WOMAC pain subscale scores [ Time Frame: Baseline to week 12 ]
  The WOMAC measures five items for pain (score range 0-20), two for stiffness (score range 0-8), and 17 for functional limitation (score range 0-68)
• Incidence of treatment-emergent adverse events (TEAEs) in patients treated with REGN5069 compared to patients treated with placebo [ Time Frame: Through the study duration (36 weeks) ]
• Incidence of imaging abnormalities consistent with accelerated arthropathies as assessed by X-ray and MRI in patients treated with REGN5069 compared to patients treated with placebo [ Time Frame: Through the study duration (36 weeks) ]
• Presence of anti-REGN5069 antibody development in patients treated with REGN5069 compared to patients treated with placebo [ Time Frame: Through the study duration (36 weeks) ]

The primary objective of the study is to evaluate the efficacy of REGN5069 compared to placebo in patients with pain due to radiographically-confirmed OA of the knee who have a history of inadequate joint pain relief or intolerance to current analgesic therapy.

The secondary objectives of the study are:

• To characterize the concentrations of functional REGN5069 in serum over time when patients are treated for up to 12 weeks
• To assess the safety and tolerability of REGN5069 compared with placebo when patients are treated for up to 12 weeks
• To measure levels of anti-drug antibodies (ADAs) against REGN5069 following multiple IV administrations

• Osteoarthritis of the Knee
• Pain

• Drug: REGN5069
  Intravenous (IV) Dose every 4 weeks (Q4W)
• Drug: Matching Placebo
  Intravenous (IV) Dose every 4 weeks (QW4)

• Experimental: REGN5069 Low Dose
  Randomized in a 1:1:1 ratio
  Intervention: Drug: REGN5069
• Experimental: REGN5069 High Dose
  Randomized in a 1:1:1 ratio
  Intervention: Drug: REGN5069
• Experimental: Matching Placebo
  Randomized in a 1:1:1 ratio
  Intervention: Drug: Matching Placebo

Key Inclusion Criteria:

• Generally in good health at the screening visit
• Body mass index (BMI) ≤39 kg/m2 at the screening visit
• Clinical diagnosis of OA of the knee on the American College of Rheumatology criteria (Altman, 1986) with radiologic evidence of OA (K-L score ≥2) at the index joint at the screening visit
• Moderate-to-severe pain in the index joint
• A history of inadequate pain relief from or intolerance to analgesics used for OA

Key Exclusion Criteria:

• Diagnosis of systemic diseases that may affect joints
• History or presence of osteonecrosis, destructive arthropathy, neuropathic joint arthropathy, pathologic fractures in any shoulder, hip, or knee joint(s), hip dislocation (prosthetic hip dislocation is eligible), or knee dislocation (patella dislocation is eligible) at the screening visit. Presence of subchondral insufficiency fracture on screening films or MRI as assessed by the central imaging reader.
• Is scheduled for a joint replacement surgery to be performed during the study period
• Received an intra-articular injection of hyaluronic acid in any joint within 90 days prior to the screening visit
• Systemic (ie, IV, oral, or intramuscular) corticosteroids within 30 days prior to the screening visit. Intra-articular corticosteroids in the index joint within 12 weeks prior to the screening visit, or to any other joint within 30 days prior to the screening visit (topical, intranasal, or inhaled corticosteroids are permitted).
• History or presence at the screening visit of multiple sclerosis, autonomic neuropathy, diabetic neuropathy, or other peripheral neuropathy
• Significant concomitant illness including, but not limited to, psychiatric, cardiac, renal, hepatic, neurological, endocrinological, metabolic, or lymphatic disease that, in the opinion of the investigator, would adversely affect the patient's participation in the study
• History of myocardial infarction, acute coronary syndromes, transient ischemic attack, or cerebrovascular accident within 12 months prior to the screening visit

Note: Other protocol defined inclusion/exclusion criteria apply.