Researchers at the Centre for Rheumatology at University College, in London, England, report in the April 2005 issue of Rheumatology the first case of a patient with severe systemic lupus erythematosus (SLE), who, having become unresponsive to the chimeric anti-CD20 antibody rituximab, exhibited a good response to a fully-human anti-CD20 antibody (hCD20) provided on a compassionate use basis by Immunomedics, Inc.¹

Although dosing was halted after the third infusion due a mild hypersensitivity reaction, The authors point out that the patient responded well clinically and serologically, exhibiting significant B-cell depletion. The patient had tested positive for the presence of human antichimeric antibodies (43,000 ng/ml) at the time of failure on rituximab.

Preclinical testing demonstrated that the hCD20 antibody possesses similar CD20 affinity and anti-B-cell potency to rituximab. The drug is currently in Phase I/II trials in the US and Europe for non-Hodgkin's lymphoma (NHL), with trials in autoimmune diseases planned, and is the second antibody in Immunomedics' pipeline to demonstrate activity in lupus patients. Epratuzumab, a humanized antibody with a long serum half-life that targets CD22 receptors on B-cells, has shown activity in indolent and aggressive NHL and in patients with moderately active SLE.

The US Food and Drug Administration recently granted its Fast Track Product designation to epratuzumab for the treatment of patients with moderate to severe SLE, and Immunomedics expects to launch two pivotal Phase III studies by the end of June 2005 for this indication. Epratuzumab is also being expanded into other autoimmune diseases, and is currently in a Phase I/II trial for Sjögren's syndrome.

1. Tahir H, Rohrer J, Bhatia A, Wegener WA, and Isenberg DA. Humanized anti-CD20 monoclonal antibody in the treatment of severe resistant systemic lupus erythematosus in a patient with antibodies against rituximab. Rheumatology. 2005;44:561-562.