This phase 3 study is a multicenter, randomized, double-blind, placebo-controlled study of lorecivivint injected intra-articularly (IA) into the target (most painful) knee joint of moderately to severely symptomatic osteoarthritis (OA) subjects at a single dose of 0.07 mg lorecivivint per 2 mL injection. This study will utilize standard outcomes to evaluate the safety and efficacy of lorecivivint.

Inclusion Criteria:

• Males and females between 40 and 80 years of age, inclusive, in general good health apart from their knee OA
• Ambulatory (single assistive devices such as canes allowed if needed less than 50% of the time, subjects requiring a walker are excluded)
• Diagnosis of femorotibial OA in the target knee by standard American College of Rheumatology (ACR) criteria at the Screening Visit (clinical AND radiographic criteria); OA of the knee is not to be secondary to any rheumatologic conditions (e.g., rheumatoid arthritis)
• Radiographic disease Stage 2 or 3 in target knee within 24 weeks of the Screening Visit according to the Kellgren-Lawrence (KL) grading of knee OA as assessed by independent central readers
• Qualifying mean score on the 24-h average pain score (0-10 numeric rating scale)
• Pain compatible with OA of the knee(s) for at least 26 weeks prior to the Screening Visit
• Primary source of pain throughout the body is due to OA in the target knee
• Body mass index (BMI) ≤ 35 kg/m2 at the Screening Visit

Exclusion Criteria:

• Pregnant women, breastfeeding women, and women who are not post-menopausal (defined as 12 months with no menses without an alternative medical cause) or permanently surgically sterile (includes hysterectomy, bilateral salpingectomy, and bilateral oophorectomy) who have a positive or indeterminate pregnancy test result at the Screening Visit or Day 1
• Partial or complete joint replacement in either knee
• Currently requires use of a lower extremity prosthesis, and/or a structural knee brace (i.e., a knee brace that contains hardware)
• Any surgery (e.g., arthroscopy) in either knee within 26 weeks prior to Day 1
• Intra-articular (IA) injection into the target knee with a therapeutic aim including, but not limited to hyaluronic acid, platelet-rich plasma (PRP), and stem cell therapies within 26 weeks prior to Day 1; or IA glucocorticoids within 12 weeks prior to Day 1 allowed
• Previous treatment with lorecivivint (SM04690)
• Participation in a clinical research trial that included the receipt of an investigational product or any experimental therapeutic procedure within 26 weeks prior to the Screening Visit, or planned participation in any such trial
• Subjects requiring the use of opioids > 1x per week within 12 weeks prior to Day 1
• History of malignancy within the last 5 years; not including subjects with prior history of adequately treated in situ cervical cancer or basal or squamous cell skin cancer
• Clinically significant abnormal screening hematology values, blood chemistry values, or urinalysis values as determined by the Investigator
• Any known active infections, including urinary tract infection, upper respiratory tract infection, sinusitis, suspicion of IA infection, hepatitis B or hepatitis C infection, and/or infections that may compromise the immune system such as human immunodeficiency virus (HIV) at Day 1
• Use of APAP or NSAIDs during washout period (between Screening Visit 2 and Day 1). Use of aspirin (up to 325 mg/day) for thrombosis prophylaxis is permitted.