Abstract
BackgroundAfter the failure of a non-steroidal aromatase inhibitor (nsAI) for postmenopausal patients with metastatic breast cancer (mBC), it is unclear which of various kinds of endocrine therapy is the most appropriate. A randomized controlled trial was performed to compare the efficacy and safety of daily toremifene 120 mg (TOR120), a selective estrogen receptor modulator, and exemestane 25 mg (EXE), a steroidal aromatase inhibitor. The primary end point was the clinical benefit rate (CBR). The secondary end points were objective response rate (ORR), progression-free survival (PFS), overall survival (OS) and toxicity.MethodsInitially, a total of 91 women was registered in the study and randomly assigned to either TOR120 (n = 46) or EXE (n = 45) from October 2008 to November 2011. Three of the 46 patients in the TOR120 arm were not received treatment, 2 patients having withdrawn from the trial by their preference and one having been dropped due to administration of another SERM.ResultsWhen analyzed after a median observation period of 16.9 months, the intention-to-treat analysis showed that there were no statistical difference between TOR120 (N = 46) and EXE (n = 45) in terms of CBR (41.3% vs. 26.7%; P = 0.14), ORR (10.8% vs. 2.2%; P = 0.083), and OS (Hazard ratio, 0.60; P = 0.22). The PFS of TOR120 was longer than that of EXE, the difference being statistically significant (Hazard ratio, 0.61, P = 0.045). The results in treatment-received cohort (N = 88) were similar to those in ITT cohort. Both treatments were well-tolerated with no severe adverse events, although the treatment of 3 of 43 women administered TOR120 was stopped after a few days because of nausea, general fatigue, hot flush and night sweating.ConclusionsTOR120, as a subsequent endocrine therapy for mBC patients who failed non-steroidal AI treatment, could potentially be more beneficial than EXE.Trial registration numberUMIN000001841
Highlights
After the failure of a non-steroidal aromatase inhibitor for postmenopausal patients with metastatic breast cancer, it is unclear which of various kinds of endocrine therapy is the most appropriate
Exemestane (EXE) is a steroidal AI with modest androgenic activity, which was studied in a phase II trial after documented progression during treatment with an non-steroidal aromatase inhibitor (nsAI), and showed a clinical benefit rate (CBR) of 20-40% [4]
Study design The high-dose toremifene (Fareston®) for patients with non-steroidal aromatase inhibitor-resistant tumor compared to exemestane (Hi-FAIR ex) study group consists of experts in breast cancer endocrine therapy from 15 facilities
Summary
After the failure of a non-steroidal aromatase inhibitor (nsAI) for postmenopausal patients with metastatic breast cancer (mBC), it is unclear which of various kinds of endocrine therapy is the most appropriate. A randomized controlled trial was performed to compare the efficacy and safety of daily toremifene 120 mg (TOR120), a selective estrogen receptor modulator, and exemestane 25 mg (EXE), a steroidal aromatase inhibitor. Non-steroidal aromatase inhibitors (nsAIs), such as anastrozole and letrozole, have been mainly employed as early recurrent treatment for postmenopausal breast cancer [2,3]. Exemestane (EXE) is a steroidal AI (sAI) with modest androgenic activity, which was studied in a phase II trial after documented progression during treatment with an nsAI, and showed a clinical benefit rate (CBR) of 20-40% [4]. In our previous retrospective study (Hi-FAIR study), TOR120 showed a CBR of 45% and ORR of 10% after prior AI [8]
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