NEW YORK (AP) — La Jolla Pharmaceutical Co. and BioMarin Pharmaceutical Inc. ended a trial of the lupus drug candidate Riquent, the companies said Thursday, after reviewers determined the drug wasn’t working. San Diego-based La Jolla developed Riquent and licensed it to BioMarin last month for up to $288.5 million. The California-based companies said they decided to stop the study after a data monitoring board found there was no reason to continue. Riquent is intended to prevent or delay renal flare-ups in patients with the autoimmune disorder lupus. About half of all lupus patients suffer from kidney disease. La Jolla is a development stage biotechnology company with no drugs currently on the market, and no other product candidates in clinical trials. Its stock tumbled $1.79, or 79.2 percent, to 48 cents per share from a Wednesday closing price of $2.31. Novato, Calif.-based BioMarin said it spent only $15 million on the drug, which it deemed a reasonable amount considering the size of the market.