Immunohistochemical Expression of mTOR in Multiple Myeloma: Retrospective Analysis of 31 Cases, a Clinicopathological...

The mammalian target of rapamycin (mTOR) pathway regulates several cellular processes and is implicated in an increasing number of neoplasms. In an attempt to explore the role of mTOR pathway in multiple myeloma, we analyzed immunohistochemical (IHC) expression of mTOR and p-mTOR (phosphorylated-mTOR) in 31 multiple myeloma patients and correlated the results with clinical parameters. On univariate analysis, there was a very high correlation between IHC expression of mTOR and p-mTOR using rabbit monoclonal antibodies that detect endogenous level of total mTOR protein and m-TOR protein phosphorylated at Ser 2448 respectively. Expression of both of these biomarkers was associated mostly with male gender. Further, older patients showed a trend towards having more mTOR positive tumors. No statistically significant difference was noted in mTOR expression between chemotherapy naïve and relapsed patients. Based on our results, we hypothesize that targeted therapy with mTOR inhibitors may have a role as an additional novel component in a subset of multiple myeloma patients.