Background: This phase II study investigated the efficacy and safety of everolimus, an inhibitor of mammalian target of rapamycin (mTOR), in locally advanced or metastatic thyroid cancer. Patients and methods: Patients with thyroid cancer of any histology that was resistant or not appropriate for 131I received everolimus 10 mg daily orally until unacceptable toxicity or disease progression. The primary end point was disease control rate [partial response (PR) + stable response ≥12 weeks]. Secondary end points included response rates, clinical benefit (PD + durable stable disease (SD)], progression-free survival (PFS), overall survival, duration of response, and safety. Results: Thirty-eight of 40 enrolled patients were evaluable for efficacy. The disease control rate was 81% and two (5%) patients achieved objective response; their duration of response was 21+ and 24+ weeks. Stable disease (SD) and progressive disease was reported in 76% and 17% of patients, respectively. Seventeen (45%) patients showed durable SD (≥24 weeks) and clinical benefit was reported in 19 (50%) patients. Median PFS was 47 weeks [95% confidence interval (CI) 14.9-78.5]. Calcitonin, CEA, and thyroglobulin concentrations were ≥50% lower than baseline in three (30%) and four (44%) patients with medullary thyroid cancer and five (33%) patients with PTC, respectively. The most common treatment-related adverse events were mucositis (84%), anorexia (44%), and aspartate transaminase/alanine transaminase elevation (26%). Conclusions: Everolimus had a limited activity with low response rate in locally advanced or metastatic thyroid cancer. Reasonable clinical benefit rate and safety profile may warrant further investigation.
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