Stock of biotech Isis Pharmaceuticals plunged 18.66% to $8.98 today (Feb. 10) as news about its experimental new cholesterol drug, mipomersen, disappointed investors. Results of a late-stage clinical trial showed that mipomersen did a good job reducing cholesterol for patients with a rare genetic disorder, hypercholesterolemia, that is found in only one of one million people. The developmental drug is also effective for another group affecting one in 500 people. While mipomersen was more effective than placebos reducing "bad" cholesterol in these tests, there were signs of possible future liver damage. The drug is being developed with Genzyme, those stock only declined 0.67% to $54.50.