A drug designed by Esperion Therapeutics ( ESPR) to cleanse coronary arteries met its primary objective in a 47-person phase II trial. The company's shares were recently up $2.35, or 16%, to $17.20 on Instinet. The stock was also upgraded Thursday by Piper Jaffray, which raised its price target to $23. In the trial, Esperion's ETC-216 resulted in a statistically significant reduction in artery hardening in a pool of 47 patients who were scheduled to undergo coronary angiography. The drug is derived from a protein called ApoA-I Milano, the major component of HDL, which is believed to protect against cardiovascular disease by removing cholesterol and other lipids from artery walls and other tissues. It's naturally present in a small population of northern Italians. Esperion said it will release further trial results when it makes a complete presentation on the study, pending additional efficacy parameters as well as safety and tolerability analyses.