Protalex, a clinical stage biopharmaceutical company, has reported preliminary results from a Phase 1b dose-escalation study of PRTX-100 in patients with active rheumatoid arthritis (RA).

The randomised, multiple-dose study based in South Africa demonstrated that PRTX-100 was generally safe and well-tolerated in patients with active RA at all dose levels.

Protalex chief medical officer William Gannon said the initial disease activity results from this trial demonstrated an acceptable safety profile and warrants further study of PRTX-100 at doses of 1.50µg/kg and higher in a new clinical trial.

"Once the full analysis of the data from the South Africa study is shortly completed, we will be better informed of the design for the new study, which we expect will provide a fuller understanding of safety and treatment effect on RA disease activity measurements, as well as help define the optimal dose," Gannon added.

The study enrolled a total of 37 patients who had active RA on methotrexate in four dose-escalating cohorts ranging from 0.15ug/kg to 1.50ug/kg of PRTX-100 or placebo, administered weekly for four weeks.

The safety and disease activity were evaluated over 16 weeks following the first dose, according to the company.

PRTX-100 has the ability, at very low concentrations, to bind to and to regulate activation of human B-lymphocytes and macrophages, which are the key cells mediating inflammation in certain autoimmune diseases.