Ligand earns million dollar payment from GSK

San Diego-based Ligand Pharmaceuticals has earned a US$1m milestone payment from GlaxoSmithKline (GSK) with that company's commencement of Phase II trials of SB-497115, an oral, small molecule drug that mimics the activity of thrombopoietin (TPO), a protein factor that promotes growth and production of blood platelets.

If the drug ultimately is approved and marketed, Ligand could receive double-digit royalties on product sales.

Thrombocytopenia (decreased platelet count) is a common side effect of many chemotherapies and can lead to uncontrolled bleeding, thus representing a significant problem in the treatment of cancer patients. Similarly, thrombocytopenia is commonly seen in patients undergoing myelosuppressive therapies or in those with leukaemias or metastatic tumours. The company estimates, based on available data, that approximately 20-25% of the nearly one million patients who undergo chemotherapy each year experience thrombocytopenia. These estimates do not include patients suffering from idiopathic thrombocytopenia. Currently, thrombocytopenia patients have few therapeutic options other than platelet transfusions.

There are no approved TPO agents for the treatment or prevention of thrombocytopenias. SB-497115 is being developed for the treatment of thrombocytopenia associated with chemotherapy or disease states such as immune thrombocytopenic purpura and chronic liver disease.

SB-497115 is the first, and most advanced in human development, non-peptide small molecule TPO receptor agonist with demonstrated activity in human bone marrow in vitro assays and pharmacological activity in humans.

'GSK's decision to move SB497115, an oral, small molecule TPO growth factor, into Phase II development is an exciting step forward for patients with thrombocytopenia,' said Dr Andres Negro-Vilar, Ligand's executive vice president of research and development and chief scientific officer. 'An oral TPO receptor agonist, if successful, will add a third key component to the hematopoietic factors (EPO, G-CSF) that have proven useful in the treatment of anaemias and neutropenias in cancer patients and in those with different hematopoietic disorders. We are also excited about SB-497115 because it is the first product to move into Phase II studies from our growth factor collaboration with GSK and represents an accelerated development and registration track opportunity with targeted NDA submission in 2006. It also underscores the continued maturation of our portfolio of 11 "big drugs" in human development which resulted from our first decade of collaborative research programmes.'