Yesterday, Motley Fool Rule Breakers pick Momenta Pharmaceuticals (NASDAQ:MNTA) announced that it had started treating patients in a phase 2 study of its lead drug, M118.

Momenta developed M118 to be a more effective and safer anticoagulant than current treatments for patients suffering from acute coronary syndromes like a heart attack. The 600 people in the phase 2 study will use M118 as an anticoagulant in conjunction with undergoing angioplasty surgeries.

The company also released safety results of a phase 1 trial of M118. Not much can be gleaned from this study because it was a small trial including 36 healthy patients. Momenta said there were no serious adverse events to report from it, but it's highly unlikely that severe cardiac or other events would emerge in such a healthy and small patient population, if they did exist.

Momenta is best known for its work on developing generic drugs of hard-to-copy blockbuster compounds like Sanofi-Aventis' Lovenox and Teva's Copaxone. It has partnered with generic-drug maker kingpin Novartis (NYSE:NVS) to develop and market these generic drugs, but still holds full worldwide marketing rights to M118.

Rule Breakers analyst Karl Thiel named Momenta his favorite drug stock earlier in the year. Shares have underperformed to date because the Food and Drug Administration has dragged its feet in deciding whether to approve Momenta's generic Lovenox product. Even if this delay continues, successfully bringing M118 through the clinic would be more than enough to make shares of Momenta a huge bargain at today's prices.

Without any effectiveness or safety data from patients actually suffering from an acute coronary episode, it's too soon to say what M118's prospects are, but at least Momenta is one step closer to finding out.

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