Safety Study of PRTX-100 With Methotrexate or Leflunomide to Treat Active Rheumatoid Arthritis

A Phase Ib Randomized, Double-Blind, Placebo-Controlled, Multiple Dose, Dose Escalation, Safety and Tolerability Study of PRTX-100 in Combination With Methotrexate or Leflunomide in Patients With Active Rheumatoid Arthritis

The purpose of this study is to determine the safety and tolerability of PRTX-100 when various doses are given 5 times at weekly intervals to patients with active rheumatoid arthritis that are taking methotrexate or leflunomide. The drug is administered in a physician's office via an intravenous infusion. PRTX-100 may be effective in rheumatoid arthritis by suppressing the immune responses.

PRTX-100 is a highly-purified bacterial protein called Staphylococcal Protein A. In this study, cohorts of patients with active RA will receive sequentially higher doses of PRTX-100. There will be an inactive placebo cohort for comparison. Patients who do not attain low RA disease activity, by a commonly used measure, will leave the study at 3 months after their first dose of study drug.

Inclusion Criteria:

• Active RA with disease duration of not less than 6 months
• Concomitant stable methotrexate or leflunomide therapy

Exclusion Criteria:

• Diagnosis of any other inflammatory arthritis
• ACR Functional Classification of IV
• Significant systemic involvement secondary to RA (except for secondary Sjogren's syndrome)
• History of clincally significant hypogammaglobulinemia, common variable immunodeficiency, or humeral immunodeficientncy
• History of active tuberculosis, pro-thrombotic disorder, venous thrombosis requiring anti-coagulation, substance abuse, or serious psychiatric condition
• History of allergy or hypersensitivity to aspirin or non-steroidal cyclooxygenase inhibitors, Staphylococcal protein A
• History or presence of malignancy (except for surgically treated basal or squamous cell carcinoma of the skin at least 3 months prior to the start of study medication)
• Uncontrolled diabetes or Type 1 diabetes
• Unstable ischemic heart disease
• Serious active or recurrent infection, hepatic cirrhosis, or other medically unstable condition
• Systemic autoimmune diseases other than RA (such as systemic lupus erythematosus, scleroderma, inflammatory bowel disease, inflammatory myopathy)
• Positive for HIV, hepatitis B surface antigen, or hepatitis C antibody
• Pregnant or nursing females
• Inadequate hepatic, renal, or hematologic function
• Receipt of live vaccine within 5 weeks of start of study medication
• Concomitant administration of other biologic or non-biologic DMARDS, corticosteroids, or anti-CD20 antibodies