Updated from 11:27 a.m. EDT.

NEW YORK (TheStreet) -- Shares of Rigel Pharmaceuticals (RIGL) - Get Report were soaring 42.61% to $3.77 on heavy trading volume late Tuesday afternoon after the company reported that its experimental drug, fostamatinib, for patients with an autoimmune platelet disease met its primary endpoint in a phase III study.

The biotechnology company reported that 18% of patients receiving the drug achieved a stable platelet response vs. none who received the placebo.

Following the results, Piper Jaffray raised its price target on shares of the San Francisco-based company to $11 from $10 and maintained an "outperform" rating in a note cited by TheFly.

The firm said the response rate leaves "little room for error," but still puts the company "in good shape."

Rigel was able to establish proof of concept with the study and has "some cushion" for the next results, Piper Jaffray noted.

More than 52.4 million shares have traded so far today vs. the 30-day average of 954,000 shares.

Separately, TheStreet Ratings objectively rated this stock according to its "risk-adjusted" total return prospect over a 12-month investment horizon. Not based on the news in any given day, the rating may differ from Jim Cramer's view or that of this articles's author.

TheStreet Ratings rated this stock as a "sell" with a ratings score of D.

Among the areas we feel are negative, one of the most important has been weak operating cash flow.

You can view the full analysis from the report here: RIGL

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