If the drug continues in development and ultimately is approved and marketed, Ligand could receive additional milestone payments and 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 myeloablative therapies or in those with leukemias or metastatic tumors.
In February 2005 Ligand earned a $1 million milestone payment after GlaxoSmithKline initiated a phase II trials of another thrombopoietin (TPO), product, SB-497115.
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. Data from a phase I study in healthy volunteers show that SB-497115 increased platelet counts in a dose-dependent fashion when administered orally.
“Glaxo’s decision to move a second, small-molecule TPO growth factor into human development is an exciting further evolution of products from our collaborative research programs, especially following so quickly after SB-497115 moving into phase II,” said Dr Andres Negro-Vilar, Ligand’s executive vice president of R&D and chief scientific officer.
“Either or both of these drugs, if successful, will add a key component to the hematopoietic factors (EPO, G-CSF) that have proven so useful in the treatment of anemias and neutropenias in cancer patients and in those with different hematopoietic disorders.”