Tumor Calcification: A New Response Pattern of Myxoid Liposarcoma to Trabectedin

Introduction: Myxoid/round-cell liposarcoma (MRCL) is a specific histological subtype that accounts for 30-35% of liposarcomas and whose virulence depends on the quantity of round-cells within the tumor. MRCL is associated with specific chromosomal translocations resulting in the formation of CHOP/FUS and CHOP/EWS fusion proteins. A high sensitivity of MRCL to trabectedin was reported. Case Report: We report the case of a 63-year-old woman with a bulky and metastatic MRCL, treated with trabectedin 1.5 mg/m2 as a first-line treatment. She experienced a long-lasting clinical benefit. The patients received 14 cycles of trabectedin and achieved a durable partial response to the metastases and a stable disease of the primary tumor, which is a very favorable safety profile. Also noteworthy is that we have observed a calcification of the primary tumor and the metastasis. The response, which lasted 30 months, led to a symptomatic improvement, associated with an excellent general condition and an absence of pain. Conclusion: To the best of our knowledge, this is the first report of a MRCL treated with trabectedin that resulted in a calcification of the primary tumor and the metastases, associated with an outstandingly long response. This case suggests that trabectedin may represent a feasible first-line therapeutic option for patients with MRCL, with meaningful clinical benefits and an acceptable safety profile.