A Retrospective Study of Patients with Malignant PEComa Receiving Treatment with Sirolimus or Temsirolimus: The Royal Marsden Hospital Experience

Perivascular epithelioid cell tumors (PEComas) are rare tumors driven by tuberous sclerosis complex gene mutations causing up-regulation of mTOR. We report the outcome of ten consecutive patients treated with sirolimus or temsirolimus. Patients and Methods: A retrospective analysis was performed on patients seen between 2007 and 2013. Demographic and treatment data were collected and radiological response was assessed. Results: Ten patients were investigated, eight females, with median age of 47.5 years. Nine patients received sirolimus, one temsirolimus. The median treatment duration was 128 (range=7-1,366 days). Temsirolimus was given at 25 mg IV weekly and median starting dose of sirolimus was 3 mg daily. Seven patients were evaluable for response by RECIST: 5 showed partial response (50%), 1 stable disease (10%) and 1 progressive disease (10%). Two patients progressed rapidly on treatment. One patient stopped due to grade 3 hyperlipidaemia although CT scan shows maintained response. Three patients continue on treatment while the remainder stopped due to disease progression. Conclusion: Our study confirms that mTOR inhibition with sirolimus/temsirolimus is well-tolerated with good radiological responses, albeit short-lived, and supports its use in PEComas.