TPO through 3-D glasses

Several years ago, thrombopoietin (TPO) was a hot molecule, with Amgen Inc. and Genentech Inc. leading the charge to push recombinant TPO into trials to treat thrombocytopenia. However, after discouraging results, Amgen gave up the pursuit and Genentech out-licensed it to Pharmacia Corp., where development has been static. Last week, 3-Dimensional Pharmaceuticals Inc. revisited the area, in-licensing GW 395058, a pegylated synthetic TPO peptide mimetic from GlaxoSmithKline plc.

Instead of focusing on past failures, DDDP (Exton, Penn.) is looking at the potential of GW 395058 based on the wealth of knowledge around the TPO pathway. TPO has been shown to stimulate megakaryocyte growth and platelet production through binding of the Mpl receptor. GW 395058, though conformationally different than the Mpl-binding site of TPO, can still activate the receptor to promote TPO responsive function. ...