Myxoid liposarcoma and the mammalian target of rapamycin pathway

PURPOSE OF REVIEW: 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. RECENT FINDINGS: 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. SUMMARY: 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.