5047 - mTOR inhibitors in uterine and extra-uterine malignant PEComas: a multicenter international case series retrospective analysis.

Background

Perivascular epithelioid cell tumors (PEComa) are exceedingly rare mesenchymal neoplasms arising from a broad variety of anatomic sites. Within the female genital tract, most frequently PEComas affect the uterus. Over the last few years, the activity of mTOR inhibitors in these neoplasms has been convincingly shown. The aim of this multicenter retrospective analysis was to compare the activity of mTOR inhibitors in uterine versus extra-uterine malignant PEComas.

Methods

We retrospectively identified pts with advanced PEComa treated with mTOR inhibitors since January 2002 at Fondazione IRCCS Istituto Nazionale dei Tumori, Milan - Italy, and within the Italian Rare Cancer Network (RTR); at the Royal Marsden Hospital, London – UK; within centers of the French and Spanish Sarcoma Groups. We stratified patients based on uterine and extra-uterine primary site and collected data on the safety and efficacy of mTOR inhibitors, including PFS and OS.

Results

A total of 41 pts with advanced PEComa treated mTOR inhibitors were analyzed. We identified 8 (20%) pts with uterine PEcomas and 33 (80%) with extra-uterine. In the group of uterine PEComas 1 out of 8 patients had a PR (12%), and 3/8 (37%) had SD with a median PFS of 4 months. In the group of extra-uterine PEComas, 16/33 (48%) had a PR, 10/33 (30%) stable disease, with a median PFS of 14 months. Two patients out of 33 were not evaluable by RECIST.

Conclusions

In our retrospective series, uterine PEComas had a numerically lower response rate to mTOR inhibitor therapy compared to those with extra-uterine primary tumors. Further work is required to confirm these preliminary data and to investigate the reasons for this observation. Our study provides a benchmark for further research and suggests that uterine PEComas may need to be analysed separately with regard to anti-tumor activity of novel agents.

Clinical trial identification

Legal entity responsible for the study

R. Sanfilippo.

Funding

Has not received any funding.

Editorial Acknowledgement

Disclosure

All authors have declared no conflicts of interest.