The purpose of this study was to characterize the local duration of exposure of TCA for 2 doses of FX006 relative to 40 mg of TCA IR in patients with OA of the knee.

This study was an open-label, single administration design, conducted in male and female patients ≥40 years of age with OA of the knee.

Patients were enrolled sequentially with 8 patients per cohort, as follows:

Cohort A: FX006 40 mg, Final Visit at Week 20 Cohort B: FX006 40 mg, Final Visit at Week 16 Cohort C: FX006 10 mg, Final Visit at Week 12 Cohort D: FX006 40 mg, Final Visit at Week 12 Cohort E: Triamcinolone acetonide immediate-release (TCA IR) 40 mg, Final Visit Week 12

Each patient was evaluated for up to 12, 16, or 20 weeks following a single IA injection depending on the assigned cohort. Following the screening visit, safety was evaluated at 3 out-patient visits and synovial fluid was collected at Day 1 for baseline measurements and the Final Visit for drug concentration measurements.

Key Inclusion Criteria:

• Written consent to participate in the study
• Willingness and ability to comply with the study procedures and visit schedules and ability to follow verbal and written instructions
• Has documented diagnosis of OA of the index knee made at least 6 months prior to Screening
• Currently meets American Collage of Rheumatology Criteria (clinical and radiological) for OA
• Index knee pain for >15 days over the last month
• Body mass index (BMI) ≤ 40 kg/m2
• Ambulatory and in good general health

Key Exclusion Criteria:

• History of Reiter's syndrome, rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, arthritis associated with inflammatory bowel disease, sarcoidosis or amyloidosis
• History of arthritides due to crystals (e.g., gout, pseudogout)
• History of infection in the index joint
• Clinical signs and symptoms of active knee infection or crystal disease of the index knee
• Presence of surgical hardware or other foreign body in the index knee
• Unstable joint (such as a torn anterior cruciate ligament) within 12 months of Screening
• IA corticosteroid (investigational or marketed) in any joint within 6 months of Screening
• IA hyaluronic acid (investigational or marketed) in the index knee within 6 months of Screening
• Oral corticosteroids (investigational or marketed) within 1 month of Screening
• Inhaled, intranasal and topical corticosteroids (investigational or marketed) within 2 weeks of Screening
• Any other IA investigational drug/biologic within 6 months of Screening
• Prior use of FX006
• Prior arthroscopic or open surgery of the index knee within 12 months of Screening
• Planned/anticipated surgery of the index knee during the study period
• Active or history of malignancy within the last 5 years, with the exception of resected basal cell carcinoma, squamous cell carcinoma of the skin, or resected cervical atypia or carcinoma in situ

Adverse Events were monitored/assessed from post-injection on Day 1 through 12 weeks for FX006 10 mg and TCA IR groups and up to 20 weeks for FX006 40 mg groups.