Myxoid liposarcoma and the mammalian target of rapamycin pathway

Abstract

Myxoid/round cell liposarcoma (MRCL) represents about 10% of all soft-tissue sarcomas. Therapeutic options for this subgroup of tumours are limited, essentially doxorubicin-based regimens and trabectedin. Recently, the mammalian target of rapamycin (mTOR) pathway has been identified as a therapeutic target in several sarcomas. MRCLs should be included among these, as various molecular aberrations of the mTOR pathway have been recently reported. PI3KCA mutations were identified in 10-20% of MRCLs. Other molecular aberrations include loss of PTEN, Akt activation and overexpression of IGF1R. Recently, two minor responses to mTOR inhibitors were reported. The relatively high frequency of mTOR signalling pathway alterations in MRCL provides a preclinical rationale for considering mTOR inhibition as a potential novel therapeutic strategy warranting further investigation.