US-based biotechnology firm Five Prime Therapeutics has started dosing in its Phase I clinical trial of FPA008, a monoclonal antibody that inhibits colony stimulating factor-1 receptor (CSF1R), to treat patients with rheumatoid arthritis (RA).
Currently being developed to treat RA and solid tumours, FPA008 has two modes of action in RA, blocking the production of multiple inflammatory cytokines and directly inhibiting the activity of osteoclasts, thus preventing bone erosion.
Five Prime senior vice-president and chief medical officer Dr Julie Hambleton said: "We are pleased with the progress we've made in the healthy volunteer portion of our Phase I clinical trial, for which we recently reported initial results at the 2014 American College of Rheumatology Annual Scientific Meeting, and are excited to be advancing into patients with active RA.
"There is still an unmet need for effective and novel RA treatments, particularly for patients who aren't responding to anti-TNF or anti-IL6 therapies.
"Because of FPA008's unique ability to both reduce inflammatory factors and prevent bone erosion, we believe it offers considerable potential as a differentiated therapeutic in the treatment of RA and other inflammatory diseases."
The randomised, double-blind, placebo-controlled, single- and multiple-ascending dose Phase I trial will evaluate FPA008 in both healthy volunteers and patients with active RA.
The trial's primary endpoint is safety, while secondary endpoints include pharmacokinetics (PK), pharmacodynamics and, in the RA patients, disease activity as measured by ACR scores and magnetic resonance imaging (MRI).
The first two parts of the three-part Phase I trial evaluated single ascending doses and then multiple ascending doses of FPA008 in healthy volunteers.
In the third part, the company will evaluate FPA008 in patients with RA who have active disease and are on methotrexate.
The company said that after an initial open label dose escalation period of FPA008 in combination with methotrexate, around 30 patients will be randomised versus a placebo control at one or two selected doses and followed for 12 weeks.
FPA008 inhibits the activation and survival of monocytes and macrophages that produce cytokines and are elevated in RA and certain tumours.