The US Food and Drug Administration (FDA) has granted orphan drug designation for AstraZeneca’s investigational MEK 1/2 inhibitor, selumetinib, for adjuvant treatment of patients with Stage III or IV differentiated thyroid cancer (DTC).

The Orphan Drug Designation program provides orphan status to drugs and biologics, which are defined as those intended for the safe and effective treatment, diagnosis or prevention of rare diseases or disorders that affect fewer than 200,000 people in the US.

Selumetinib is an oral, potent, selective inhibitor of MEK, part of the mitogen-activated protein kinase (MAPK) pathway, which is frequently activated in cancer, including those with the KRAS mutation, which is present in 20% of human cancers and 20-30% of non-small cell lung cancer tumors. MAPK activation also inhibits expression of thyroid hormone biosynthesis genes, including the sodium/iodine symporter, which facilitates iodine uptake into cells. Pre-clinical studies have suggested that following MAPK inhibition, iodine uptake by thyroid tumor cells is regained.

The drug is being tested in Phase III trials in patients with DTC who are at high risk of recurrence. It is also being tested in a Phase II study of patients with advanced thyroid cancer, a Phase III trial of patients with KRAS-mutant advanced non-small cell lung cancer, and in a Phase II registration trial of pediatric and adolescent patients with neurofibromatosis Type 1.

AstraZeneca acquired exclusive worldwide rights to selumetinib from Array BioPharma Inc. in 2003.

Source: AstraZeneca