MEK Inhibitor Mirdametinib (PD-0325901) in Patients With Neurofibromatosis Type 1 Associated Plexiform Neurofibromas

Neurofibromas are non-malignant peripheral nerve sheath tumors, which are classified as plexiform neurofibromas (PNs) if they extend longitudinally along a nerve and involve multiple fascicles. PNs are a major cause of morbidity and disfigurement in individuals with NF1, and as the tumor growth progresses, can cause a multitude of clinical problems including pain and impaired physical function. PNs have the potential to undergo malignant transformation to Malignant Peripheral Nerve Sheet Tumors (MPNST). Mirdametinib (PD-0325901) is an orally delivered, highly selective small-molecule inhibitor of the dual specificity kinases, MEK1 and MEK2 (MAPK/ERK Kinase) which prevents the phosphorylation and subsequent activation of mitogen-activated protein kinase (MAPK). Previous studies of mirdametinib (PD-0325901) demonstrated PN shrinkage and sustained inhibition of pERK. Reduced tumor volume indicated that cell proliferation or cell death may be altered in PNs with administration of mirdametinib (PD-0325901).