No new drugs to treat lupus have been approved in over 50 years. Physicians currently have precious few choices for lupus treatment: chemotherapy, steroids that can control inflammation, and a malaria drug that works in some patients. But the side effects of harsher treatments can be so severe that "as many patients die from that as those who die from lupus," says Tammy Utset, associate professor at the University of Chicago Medical Center who was also an investigator in the Benlysta trials.

Much of the challenge in developing lupus drugs stems from the variability of the disease. Some patients suffer flares frequently, for example, while others might get them only once a year. And the symptoms can strike many different organs. That makes measuring the response to an experimental drug difficult, says Sandra Raymond , CEO of the Lupus Foundation of America. To standardize these measurements, Human Genome Sciences worked closely with the U.S. Food and Drug Administration to develop a composite index that measures response to Benlysta according to several different parameters, including the number of both severe and moderate flares. The index also includes global assessments by treating physicians of whether or not the patients are getting worse. "What that's done is carved a pathway for other companies, because they've put together an index that really gets at how the patient is feeling," Raymond says.

Cephalon has yet to announce the timing of its phase III program or details about how it will measure patient response to Lupuzor in those trials. Still, the fact that there are any products at all in late-stage testing is a welcome relief to physicians like Kyriakos Kirou, a rheumatologist at the Mary Kirkland Center for Lupus Care at Hospital for Special Surgery in New York. "The drugs we have now are nonspecific and not very potent," Kirou says. "We need to strike the right balance in controlling the immune system, and hopefully these new medicines will do a better job of that. It's a very exciting time in lupus."