Clinical stage biopharmaceutical company Protalex has enrolled and dosed the first patient in its Phase Ib trial evaluating PRTX-100 in patients with active rheumatoid arthritis.
Protalex has formulated PRTX-100 with a proprietary highly purified form of Staphylococcal Protein A.
The sequential dose escalation phase of the study will enrol up to 40 patients into the dose escalation cohorts, starting at 1.5µg/kg PRTX-100 or placebo, and may be followed by up to 12 additional randomised patients for cohort expansion.
The company expects to carry out enrolment at study sites in both the US and South Africa.
The randomised, multiple-dose study's primary objective is to assess the safety and tolerability of intravenous PRTX-100 administered weekly over five weeks in patients with active rheumatoid arthritis on methotrexate therapy.
The dose-escalation study's secondary objectives comprise determining the effects of PRTX-100 on measures of disease activity, assessing the immunogenicity and evaluating the pharmacokinetic parametres after repeated doses, determining possible relationships between the immunogenicity of PRTX-100 and safety, PK and efficacy parametres.
A previous Phase Ib trial conducted in adult patients with active rheumatoid arthritis in South Africa has demonstrated that PRTX-100 was generally safe and well tolerated at all dose level and at the higher doses.
In this trial, more patients showed improvement in their Clinical Disease Activity Index for RA than did patients at the lower dose or placebo cohorts.
At very low concentrations, PRTX-100 can bind and regulate activation of human B-lymphocytes and macrophages that mediate inflammation in certain autoimmune diseases.