The ACR50 response rate will be determined for Natrunix treatment in comparison with MTX (+folate). There will be a total study population of 150 subjects with 1:1 randomization (75 subjects receiving Natrunix + MTX placebo (+folate) and 75 receiving Natrunix placebo + MTX (+folate)).~Patients will undergo a preliminary assessment for study eligibility. Patients who meet the eligibility criteria will be screened and be required to provide an informed consent to acknowledge understanding and accept enrollment in the clinical study. Subjects enrolled will be randomized in a 1:1 ratio to receive either test article (Natrunix) + MTX placebo OR Natrunix placebo + MTX (+folate). Four weeks are allotted to complete all screening procedures. During the screening period, certain treatments will be washed out (discontinued), as applicable, according to eligibility requirements.~Clinical assessments and collection of blood samples for Natrunix pK determination or other analysis will be performed at specified clinic visits. Natrunix + MTX placebo (+folate) OR Natrunix placebo + MTX (+folate) will be administered weekly for 12 weeks. After 13 weeks, the study will conclude. All data must be entered into the database in a timely manner, including data from the last visit.~Patients will receive the following treatments every week: 400 mg Natrunix or Natrunix placebo injected subcutaneously once a week, followed by MTX placebo or MTX taken orally once a week respectively and a minimum of 1 mg folic acid taken orally every day or 5 mg of folinic acid taken orally once a week.~A patient should start on a reduced dose of 7.5 mg of MTX or MTX placebo at visit 1. On day 5 (5 days after the first dose), the patient laboratory findings are checked and if there are no clinically significant findings, the dose of MTX or MTX placebo may be increased up to 15 mg once weekly and maintained throughout the study. The dose of MTX may range from 7.5-15 mg once weekly based on discretion of the Principal Investigator.
Phase II Double-Blinded, Placebo-Controlled Randomized Study Examining the Safety and Efficacy of Natrunix versus MTX (+folate) for the Treatment of Rheumatoid Arthritis