To maintain their drug franchises, large cap biotech companies have begun to advance modified versions of their best-selling drugs closer to the markets they already dominate. Amgen Inc. (AMGN, Thousand Oaks, Calif.), for example, is in Phase III testing of NESP (Novel Erythropoiesis Stimulating Protein), a version of its Epogen erythropoietin that has five amino acids changed to increase glycosylation, half-life and potency.

Similarly, Genentech Inc. (GNE, South San Francisco, Calif.) last week announced positive data from its 17,000-patient Phase III ASSENT 2 trial at the American College of Cardiology meeting. ASSENT 2 compared GNE's marketed heart attack thrombolytic Activase alteplase tPA with tenecteplase TNK-tPA. TNK-tPA is a version of Activase that has 6 amino acids changed at 3 sites in