Toremifene and tamoxifen in advanced breast cancer--a double-blind cross-over trial. Phase III randomized trial of toremifene vs tamoxifen in hormonodependant advanced breast cancer. Meta-analysis of trials comparing toremifene with tamoxifen and factors predicting outcome of antiestrogen therapy in postmenopausal women with breast cancer. Randomized comparison of tamoxifen and two separate doses of toremifene in postmenopausal patients with metastatic breast cancer. Comparison of toremifene and tamoxifen in post-menopausal patients with advanced breast cancer: a randomized double-blind, the 'nordic' phase III study. A phase III comparison of two toremifene doses to tamoxifen in postmenopausal women with advanced breast cancer. Eastern European Study Group. Phase III, double-blind, controlled trial of atamestane plus toremifene compared with letrozole in postmenopausal women with advanced receptor-positive breast cancer.
Toremifene (TOR) is a triphenylethylene derivative related to tamoxifen (TAM). TOR has antitumor activity, not dependent on estrogen receptors, and responses with TOR have been observed in patients with progressive disease during TAM-treatment. To elucidate possible cross-resistance between these two antiestrogens, we compared their anti-tumor activity in a randomized, double-blind, cross-over study. 66 postmenopausal women with advanced estrogen receptor positive or unknown breast cancer and a median age of 63 years (range 38-82) were included. Patients were randomized to TAM 40 mg/day or TOR 240 mg/day. Treatment continued until progressive disease, when cross-over to the alternative treatment was done. The response rate with first line TOR was 29% (95% confidence limits 10-41%) and with TAM 42% (95% confidence limits 25-61%). Response rates and response durations, survival and toxicity were not significantly different between the two treatments. 44 patients progressing on first line TAM or TOR were evaluable for second line TOR or TAM treatment. As no responses were observed, the possibility of over-looking a response rate of 20% or more is less than 1%. In conclusion, this study strongly indicates that TOR and TAM are clinically cross-resistant in patients with advanced breast cancer. Efficacy and safety of toremifene (TOR) 60 mgs/dayly/o.r. was compared with tamoxifen (TAM) 40 mgs/dayly/o.r. in a group of postmenopausal women with advanced breast cancer, without previous systemic therapy for advanced breast cancer.
                The study was a prospective double-blind randomized trial. All treated patients presented with positive estrogen receptors. Main end points were response rates, toxicity profile analysis, time to progression and survival. WHO and ECOG criteria were employed for response evaluation while toxicity was assesed according to WHO guidelines. Curves were constructed by means of Kaplan-Meier methodology and were compared by means of log-rank test.
                From January 1996 to January 1999 a total of 217 patients were included in the study (106 in the TOR branch and 111 in the TAM arm). Both groups of patients were homogeneous regarding the main prognostic factors. A response rate of 64% (68/106) was observed in the TOR group as compared with a 52% (58/111) in the TAM group. Median times to progression and overall survival were not significantly different. A lower incidence of undesirable effects was apreciated in the TOR arm.
                Our data suggest that TOR is an efficient and well-tolerated agent for the therapy of postmenopausal women with hormonal positive receptors advanced breast cancer, and must be considered an alternative to TAM as first line therapy for ER+ advanced breast cancer patients and as well as an adjuvant treatment. Meta-analysis of all clinical data was conducted to compare toremifene 40-60 mg/day (TOR) with tamoxifen 20-40 mg/day (TAM) in postmenopausal women with estrogen receptor (ER) positive or ER unknown advanced breast cancer and assess factors predicting treatment outcome. Data from five randomized parallel group studies (all studies) were combined. Efficacy variables were the response rate in all studies and also the time to treatment failure and survival in the three major studies (pivotal studies). Of the 1421 patients, 725 received TOR and 696 TAM. Response rates were 24.0% and 25.3%, respectively (p = 0.675) with 95% confidence interval (95% CI) for the difference -5.3 to 3.4. Of the 1157 patients in the pivotal studies, 75% had progressed and 50% expired. Median treatment times were 4.9 months in TOR and 5.3 months in TAM groups (p = 0.762, hazard ratio 0.98 with 95% CI 0.87-1.11). Median survival times were 31.0 (TOR) and 33.1 (TAM) months (p = 0.758, hazard ratio 0.98 with 95% CI 0.83-1.15). All results are consistent with the criteria of statistical equivalence between TOR and TAM. More patients in TAM (20%) than in TOR (14%, p = 0.007) discontinued the treatment prematurely but overall the treatments were well tolerated. As the treatments were equally effective all data were analyzed together for predictive factors. High tumor ER concentration, long disease free time, soft tissue metastases, few metastatic sites, and good performance status all independently predicted longer survival (p<0.001). Previous adjuvant tamoxifen predicted shorter survival (p = 0.008). Objective response to treatment or disease stabilization for at least 12 months both predicted prolonged survival (p = 0.001). TOR 60 mg/day and TAM are equally effective and well tolerated in the treatment of advanced breast cancer in postmenopausal women. Probability of survival may be predicted based on patient characteristics and on the initial response to the treatment. To perform a randomized three-arm comparison of tamoxifen (TAM; 20 mg/d) and two separate doses of toremifene (TOR; 60 mg/d [TOR60] and 200 mg/d [TOR200]) in postmenopausal patients with hormone receptor-positive or -unknown metastatic breast cancer.
                Six hundred forty-eight patients with hormone receptor-positive or -unknown metastatic breast cancer were randomly assigned to receive TAM (n = 215), TOR60 (n = 221), or TOR200 (n = 212).
                The combined response rates (by intent to treat) were as follows;: TAM, 44%; TOR60, 50%; and TOR200, 48%. Complete and partial response rates were as follows: TAM, 19%; TOR60, 21%, and TOR200, 23% (not statistically different). Median times to progression and overall survival were not significantly different. Adverse events (lethal, serious but nonlethal, and important but non-life-threatening) were similar in all three arms, except that patients in the TOR200 arm had a statistically significantly increased rate of nausea (37% v 26% and 26% for TOR200, TAM, and TOR60, respectively; P = .027). Quality-of-life assessments were not different among the three arms.
                The activity, toxicity, and side effects of TOR in postmenopausal women with hormone receptor-positive or -unknown metastatic breast cancer are similar if not equivalent to those of TAM. We detected no clear evidence of a dose-response effect for TOR. TOR60 is an effective and safe agent for the treatment of postmenopausal women with hormone receptor-positive metastatic breast cancer and can be considered an alternative to TAM as first-line treatment for such patients. The study was planned to compare, in a prospective double-blind randomized trial, the efficacy and safety of toremifene (TOR) and tamoxifen (TAM) in post-menopausal patients with advanced breast cancer who have not had prior systemic therapy for advanced disease. Four hundred and fifteen post-menopausal patients with oestrogen receptor (ER)-positive or ER-unknown advanced breast cancer were randomly assigned to receive daily either 60 mg TOR or 40 mg TAM. The patients were stratified to measurable and non-measurable but evaluable groups. They were assessed for response to therapy, time to progression (TTP), time to treatment failure (TTF), response duration, overall survival and drug toxicity. Two hundred and fourteen patients were randomized into TOR and 201 into TAM treatment. The response rate (complete + partial) was 31.3% for TOR and 37.3% for TAM (P = 0.215). The 95% confidence interval (CI) for the 6% difference was -15.1% to 3.1%. The median TTP was 7.3 months for TOR and 10.2 months for TAM (P = 0.047). The 95% CI for the hazard ratio of 0.80 was 0.64-1.00. A percentage of the TOR patients (9.8%) and the TAM patients (18.9%) discontinued the treatment prematurely (P = 0.011) for various reasons. Consequently, the median TTF of 6.3 vs 8.5 months did not differ significantly (P = 0.271). The hazard ratio was 0.89 and the subsequent 95% CI 0.73-1.09. The median overall survival was 33.0 months for TOR and 38.7 months for TAM (P = 0.645). The hazard ratio was 0.94 with 95% CI of 0.73-1.22. The transient difference in TTP may be related to an imbalance in ER content of the tumours. When only patients with ER-positive tumours were considered (n = 238), no difference between two treatments was seen (P = 0.578). TAM was associated with an overall slightly higher frequency of adverse drug reactions than TOR (44.3 vs 39.3%) and a higher discontinuation rate due to these events (3.5% vs 0.9%). Treatment-emerged moderate dizziness (P = 0.026) and cataracts (P = 0.026) were more frequent among TAM than among TOR patients. In conclusion, TOR (60 mg day(-1)) and TAM (40 mg day(-1)) are equally effective and safe in the treatment of advanced post-menopausal ER-positive or ER-unknown breast cancer. Efficacy and safety of toremifene 60 and 240 mg daily (TOR60 and TOR240) are compared to 40 mg tamoxifen daily (TAM40) in postmenopausal women with advanced estrogen receptor (ER) positive or ER unknown breast cancer. The study is randomized and open label in three parallel groups. Primary efficacy variables are response rate and time to progression. WHO and ECOG criteria were used for measurable and nonmeasurable disease assessment, respectively. Safety was reported according to WHO criteria. Altogether 463 patients were randomized (157 to TOR60, 157 to TOR240, and 149 to TAM40). By data cut-off, after 20.5 months median follow-up time, over 70% of the patients had experienced disease progression. Response rates are 20.4%, 28.7%, and 20.8% in TOR60. TOR240, and TAM40, respectively. TOR60 and TAM40 show statistically equivalent efficacy and the difference between TOR240 and TAM40 is not significant (P = 0.112). Median times to progression are 4.9 (TOR60), 6.1 (TOR240), and 5.0 (TAM40) months and the corresponding hazard ratios (TAM:TOR) 1.015 and 1.124. Again, TOR60 and TAM40 are statistically equivalent and the difference between TOR240 and TAM40 is not significant (P = 0.374). All treatments were well tolerated. As a conclusion, TOR60 and TAM40 show equivalent clinical efficacy and tolerability. The higher dose of toremifene slightly but not statistically significantly improves response rate and time to progression. In postmenopausal women, toremifene 60 mg daily is an effective and safe treatment of advanced ER-positive or ER-unknown breast cancer. To compare time to progression (TTP) with a steroidal aromatase inhibitor (AI) atamestane (ATA) combined with toremifene (TOR; complete estrogen blockade) versus letrozole (LET) in receptor-positive advanced breast cancer (ABC).
                Eligibility included postmenopausal receptor-positive ABC and adjuvant hormonal therapy completed more than 12 months prior to study entry. Participants received daily ATA 500 mg with TOR 60 mg (ATA + TOR), or letrozole 2.5 mg (LET). The primary end point was TTP, whereas secondary objectives included objective response (OR), overall survival (OS), and time to treatment failure (TTF). The study had 80% power to detect a 25% increase in TTP assuming a TTP of 9.4 months in the LET population.
                A total of 865 patients were randomly assigned (434 to ATA + TOR and 431 to LET) in 60 centers in the United States, Canada, Russia, and Ukraine. Baseline characteristics were balanced. Median TTP was identical in the two arms at 11.2 months (P < .92). Median TTF was similar at 9.24 months (ATA + TOR) versus 10.44 months (LET). The hazard ratios (LET/ATA + TOR) were 1.00 (95% CI, 0.92 to 1.08) for TTP, 0.99 (95% CI, 0.92 to 1.06) for TTF, and 0.98 (95% CI, 0.87 to 1.11) for OS. OR occurred in 30% of patients receiving ATA + TOR and in 36% of patients receiving LET (P < .1). Adverse events (AEs) were similar for patients receiving ATA + TOR versus LET, and serious AEs were 10% v 11%, respectively.
                TTP for patients receiving ATA + TOR was identical to that for patients receiving LET, representing the first endocrine therapy comparable to LET in ABC. Unlike in the Anastrozole, Tamoxifen, and Combined trial, addition of an antiestrogen did not decrease efficacy of the AI. Future studies of AIs in combination with more effective selective estrogen receptor modulators or selective receptor downregulators is warranted.
TOR and TAM are equally effective and the safety profile of the former is at least not worse than the latter in the first-line treatment of patients with advanced breast cancer. Thus, TOR may serve as a reasonable alternative to TAM when anti-oestrogens are applicable but TAM is not the preferred choice for some reason.