Shares of La Jolla Pharmaceutical Co. shot to a two-year high Monday after a Pacific Growth Equities analyst said data from a clinical trial of Riquent, its lupus treatment, was better than expected.

Analyst Liana Moussatos upgraded La Jolla shares to "Buy" from "Neutral." On Thursday, the San Diego-based company reported that lupus patients treated with 300 milligrams or 900 milligrams of Riquent per week showed significantly more improvement than those treated given just 100 milligrams per week.

"We believe this is significant as 100 mg was the highest dose tested in previous pivotal studies and the level of antibody reduction achieved with 900 mg has been correlated with potential clinical benefit," Moussatos said. We anticipate a potential top-line data release in early 2009, launch in early 2010 and potential peak U.S. sales of about $378 million."

Shares of La Jolla Pharmaceuticals gained $1.79, or 30.3 percent, to close at $7.70 on the Nasdaq Stock Market, having hit a new high of $8.14 earlier in the session. Previously, the stock traded in a 52-week range of $2.77 and $6.85.