Rapid and Durable Response With Nab-Sirolimus After Everolimus Failure in a Patient With Perivascular Epithelioid Cell Tumors (PEComas) of the Uterus.

Perivascular epithelioid cell tumors (PEComas) are rare mesenchymal tumors with a natural history ranging from indolent benign lesions to ones with an aggressive clinical course including distant metastases. Recent reports have suggested that mTOR inhibitor sirolimus and related drugs show some benefit in non-tuberous sclerosis complex PEComas. However, therapeutic options for patients who progress on sirolimus are very limited. We describe a patient with metastatic uterine PEComa, who progressed on mTOR inhibitor everolimus but had a rapid and durable response to nab-sirolimus.