Therapeutic Approaches to Radiation-Induced Fibrosis.

Radiation induced fibrosis (RIF) is a common morbidity in patients being treated for cancer with radiation. Off-target effects result in intense inflammatory responses which ultimately results in the generation of extracellular matrix (ECM) producing myofibroblasts which mediate a progressive fibrosis resulting in scarring and organ and tissue dysfunction. Unfortunately, currently, there are no effective therapies to block the excess accumulation of ECM. We have previously reported on the use of trametinib, a MEK inhibitor, to essentially block the formation of abdominal adhesions in a mouse model of cecal abrasion. Using this drug in the mouse model, the complete trans-differentiation of precursor cells into ECM-producing myofibroblasts was blocked. Trametinib is a potentially powerful drug to thwart organ and tissue fibrosis in RIF because it has a potential dual function in that it may block RIF as well as prevent radiation-resistance. Given the intractability of RIF, trametinib should be considered for more extensive testing.