The drug has received the designation as it has potential to treat a disorder that affects less than 200,000 people in the US. The status confers several benefits including seven years of market exclusivity in the US upon approval of the drug.
The drug is designed to be a multitargeted compound, directed to the inhibition of key cell-signaling pathways involved in tumor growth and spread. Zactima is being developed to tackle follicular, medullary, anaplastic, locally advanced and metastatic papillary thyroid cancer.
Tumor cells are targeted through inhibition of epidermal growth factor receptor (EGFR) and RET tyrosine kinases, while tumor blood supply is targeted through inhibition of vascular endothelial growth factor receptor (VEGFR) tyrosine kinase. RET tyrosine kinase activity is an important growth driver in certain thyroid tumors.
Zactima is currently in phase II clinical trials in medullary thyroid cancer as well as phase III clinical trials in advanced non-small-cell lung cancer.