By Lisa Seachrist

Washington Editor

La Jolla Pharmaceutical Co.¿s (LJP) stock toppled 51 percent on news that the company had halted a Phase II/III study of its lupus drug, LJP 394, after the drug failed to meet its primary endpoint in a planned interim analysis of the data.

San Diego-based LJP disclosed the results Wednesday after the market closed, and the company¿s shares (NASDAQ:LJPC) closed Thursday at $1.593, down $1.718.

LJP 394, based on the company¿s Toleragen technology, was being tested against placebo as a way to prevent or delay potentially life-threatening renal flares. As a secondary consideration, LJP 394 was being evaluated on its ability to reduce disease activity, permit lower doses of steroids and chemotherapy, and improve overall quality of life.

The interim analysis, conducted by an independent data monitoring committee, didn¿t consider the secondary endpoints.

¿We did see a reduction in auto-antibodies,¿ said Richard Krawiec, vice president of investor relations for LJP. ¿What¿s puzzling is why we didn¿t see a reduction in the time to renal flare.¿

While the study remains blinded, the committee noted no safety concerns were evident from its analysis.

Krawiec said that, following discussions with the FDA, LJP and its partner, Abbott Laboratories, of Abbott Park, Ill., decided to stop enrollment and treatment in the Phase II/III trial until the data can be validated and analyzed. In addition to the Phase II/III study, LJP 394 is being tested in a Phase II dose-ranging study, which the two companies have decided to complete.

Lupus is a chronic, lifelong, potentially fatal disease in which B cells, normally producers of disease-fighting antibodies, instead create disease-causing auto-antibodies. Lupus affects about 500,000 Americans, 90 percent of whom are women.

The potential treatment market is estimated to be at least $1 billion. A large percentage of lupus sufferers ultimately die of kidney failure. The second most common cause of death is complications arising from the use of current therapies: steroids and chemotherapy.

LJP 394, given intravenously, is designed to reduce the levels of the auto-antibodies to double-stranded DNA that are believed to promote lupus kidney disease. Specifically, the molecule is designed to suppress the production of the renegade B cells responsible for making pathogenic antibodies, without suppressing the entire immune system.

The LJP 394 molecule comprises four double-stranded deoxyribonucleotide strands conjugated to a triethylene glycol platform, designed to cross-link B-cell receptors, thus sending a signal that shuts down antibody production.

¿This study did show that we could reduce the auto-antibody levels in humans,¿ Krawiec said. ¿We will be looking at the other endpoints to see what effect LJP 394 had on those.¿

In addition to LJP 394, the company is developing products to prevent rejection in xenotransplantation and antibody-mediated thrombosis.

The company has $21 million in cash on hand, and ¿a relatively modest burn rate,¿ Krawiec said. ¿This was disappointing news, but the biggest disappointment is for the lupus patients who haven¿t seen a new therapy in almost two decades.¿ n