Treatment with nab-sirolimus yielded durable responses in patients with malignant perivascular epithelioid cell tumors (PEComa), according to research published in the Journal of Clinical Oncology.

In the phase 2 AMPECT study (ClinicalTrials.gov Identifier: NCT02494570), researchers evaluated the safety and efficacy of nab-sirolimus in patients with malignant PEComa.

Researchers enrolled and treated 34 patients. The patients’ median age was 60 years (range, 27-78 years), 82% were women, 71% were White, and 76% had a performance status of 0. Patients had metastatic disease (85%) or inoperable, locally advanced disease (15%), and 12% had received prior systemic therapy for advanced PEComa.


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The patients received nab-sirolimus at 100 mg/m2 intravenously once weekly for 2 weeks in 3-week cycles until disease progression or unacceptable toxicity.

There were 31 patients evaluable for efficacy. According to independent review, the overall response rate was 39%. This included 1 complete response and 11 partial responses. The disease control rate was 71%, the rate of stable disease was 52%, and 10% of patients had progressive disease.

Responses occurred within 6 weeks in 67% of patients. At a median follow-up of 2.5 years, the median duration of response was not reached.  

A multivariate analysis revealed that TSC2-inactivating mutations (P <.001) and pS6 expression (P =.004) were associated with response. Responses were seen in 89% of patients with a TSC2 mutation and 13% of patients without a TSC2 mutation. The response rate was 59% in patients with pS61-positive tumors and 0% in patients with pS61-negative tumors.

The median progression-free survival (PFS) was 10.6 months. The PFS rate was 79% at 3 months, 69% at 6 months, and 47% at both 12 months and 24 months.

The median overall survival (OS) was 40.8 months. The OS rate was 93% at 6 months, 89% at 12 months, and 70% at 24 months.

A majority of treatment-related adverse events (TRAEs) were grade 1 or 2 in nature, and there were no grade 4 or 5 TRAEs. The most common TRAEs were mucositis (79%), fatigue (59%), rash (56%), anemia (47%), and thrombocytopenia (32%).

“The response rate, durability of response, disease control rate, and safety profile support that nab-sirolimus represents an important new treatment option for this disease,” the researchers wrote.

Disclosures: This research was supported by Aadi Bioscience. Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.

Reference

Wagner AJ, Ravi V, Riedel RF, et al. Nab-sirolimus for patients with malignant perivascular epithelioid cell tumors. J Clin Oncol. Published online October 12, 2021. doi:10.1200/JCO.21.01728