Seattle-based ZymoGenetics (NASDAQ: [[ticker:ZGEN]]) said today that its sole marketed product was able to be safely given to patients with excess surgical bleeding, without provoking an immune system reaction. The study was of 205 patients who were at increased risk for having reactions against the standard product derived from cow blood, marketed by King Pharmaceuticals as Thrombin-JMI. The study found that none of the patients developed immune reactions against the ZymoGenetics drug, marketed as Recothrom, which is made differently, through genetically engineered copies of a human clotting protein. The product has gotten off to a lackluster start in its first year on the market, and is expected to generate $7 million in sales this year, the company has said.