Aromatase inhibitors may be beneficial in endometrial stromal sarcomas
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In a study of patients with endometrial stromal sarcomas treated with aromatase inhibitors the objective response rate was more modest than expected, but a majority did achieve stable disease, according to a study presented at the ASCO Annual Meeting.
Because account for only 7% to 25% of uterine mesenchymal tumors, researchers have had difficulty conducting large clinical trials in this patient population and treatment is currently guided by small retrospective studies.
To evaluate the role of aromatase inhibitors (AIs) in the treatment of endometrial stromal sarcomas, researchers conducted a retrospective chart review of all patients treated in the gynecology oncology department at Memorial Sloan Kettering Cancer Center between 1998 and 2020.
Fionnuala Crowley, MD, a PGY2 internal medicine resident at Mount Sinai Morningside West, and colleagues identified 48 patients with endometrial stromal sarcomas (median age, 54 years; median BMI, 27; 79% white) treated with AIs during the study period. All patients were menopausal at the time of AI initiation. Among the 48 patients observed, 12 had synchronous cancers. The majority of patients had stage III and IV cancers, and of the 39 patients with available hormone status, 37 were ER-positive/PR-positive and two were ER-positive/PR-negative.
Patients were treated with different AIs such as letrozole (73%), anastrozole (44%) and exemestane (39.6%), with 45.8% of patients receiving treatment with two or more AIs.
Fifty-eight percent of patients experienced adverse events and 25% switched AIs due to toxicity. Of those who switched, two-thirds tolerated the second AI better than the first. Overall, though, 20.8% of all patient discontinued treatment due to adverse events.
Although the objective response rate was 8.3%, which was lower than reported in previous studies, only 25% of patients had disease progression and 67% of patients achieved stable disease as their best response.
At the time of data analysis, 67% of patients were still alive, preventing calculation of median overall survival, but median progression-free survival was 161.6 months, according to the data.
Researchers noted that patients who progress on one AI might benefit from trial of a second AI.
“This study represents the largest study of AI use in endometrial stromal sarcomas,” Crowley said during a virtual poster presentation. “Our ORR was more modest than previously reported. The majority of our patients achieved stable disease with a disease control rate of 58% even in the stage-IV setting. We eagerly await the results of a phase 2 clinical trial studying the interruption vs. maintenance AI in locally advanced metastatic endometrial stromal sarcoma, which is currently underway.”
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Crowley F, et al. Abstract 5575. Presented at: ASCO Annual Meeting; June 4-8, 2021 (virtual meeting).
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