Estrogen provision by reactive glia decreases apoptosis in the zebra finch (Taeniopygia guttata).

Upregulation of aromatase (estrogen synthase) in glia around the site of neural injury may limit neural degeneration. Systemic administration of estrogen limits neural damage, but the specific role of local estrogen provision in this effect is unclear. In male zebra finches, we tested the effect of local aromatase inhibition and estrogen replacement on type of cellular degeneration and the distance of this degeneration from the source of insult. Subjects received injections of the aromatase inhibitor fadrozole into one telencephalic lobe and fadrozole and estradiol into the contralateral lobe. Seventy-two hours later, we used Fluoro-Jade B and TUNEL to label dying and apoptotic cells, respectively. Since each subject was its own control, we were able to assess the influence of local estrogen replacement in relative distinction from circulating steroids and constitutive aromatization. Cellular degeneration around the lesion was measured with Fluoro-Jade B, TUNEL, and indirectly with aromatase expression. Additionally, the glial nature of aromatase-positive cells around the injury was queried by co-localization with vimentin. The estrogen replaced injury had fewer apoptotic cells clustered more closely around the injury compared to the hemisphere injected with fadrozole alone. Since Fluoro-Jade B and TUNEL labeled similar numbers of cells, and the distance of these cells from the injection was identical, we suggest that estrogen replacement functions primarily to restrict apoptosis in the current paradigm. Lastly, aromatase-positive cells around injuries co-localize vimentin, establishing their glial nature. Thus, glial estrogen provision at sites of neural insult may be critical in limiting the cellular degeneration caused by injury via an inhibition of apoptosis.

Lack of efficacy of fadrozole in treating precocious puberty in girls with the McCune-Albright syndrome.

We administered the aromatase inhibitor fadrozole to 16 girls with gonadotropin-independent precocious puberty due to the McCune-Albright syndrome. The girls' ages ranged from 3.2-9.7 yr, and their bone ages ranged from 5.75-14.25 yr. After baseline evaluations, fadrozole was started at a dose of 240 microg/kg.d (equivalent to the dose recommended for therapy of estrogen-dependent breast cancer) for 12-21 months and increased to 480 microg/kg.d for an additional 12 months in 10 girls. During treatment, seven girls had evidence of central precocious puberty; hence, the GnRH agonist deslorelin (4 microg/kg.d sc) was added to their regimen. One girl was on a long-acting GnRH agonist from the start of treatment. Patients were evaluated at 2-6-month intervals throughout treatment. After the first 6-12 months of treatment, fadrozole showed some benefits in 10 girls, including decrease in frequency of menses and/or rates of linear growth and bone maturation; however, fadrozole had no significant benefit in the group as a whole. The seven girls with evidence of central precocious puberty had no slowing in the progression of their puberty during the combined fadrozole and GnRH analog treatment. Adverse effects of fadrozole included inhibition of cortisol and aldosterone biosynthesis at the dose of 480 microg/kg.d, without clinical evidence of adrenal insufficiency. In addition, three patients complained of nonspecific abdominal pain during fadrozole treatment. In one patient, this resolved with a reduction in dose from 480 to 240 microg/kg.d; in two patients, it resolved spontaneously. One girl had muscle weakness and constipation on the 480 microg/kg.d. This resolved after discontinuation of the drug. We conclude that fadrozole is not sufficiently potent to block estrogen synthesis in most girls with gonadotropin-independent precocious puberty due to the McCune-Albright syndrome and may impair the adrenocortical stress response.

Double-blind randomised trial comparing the non-steroidal aromatase inhibitors letrozole and fadrozole in postmenopausal women with advanced breast cancer.

BACKGROUND: To compare the efficacy, safety and tolerability of letrozole, an advanced non-steroidal aromatase inhibitor, and fadrozole hydrochloride, an older-generation drug in this class, we conducted a randomised double-blind trial in postmenopausal women with advanced breast cancer. PATIENTS AND METHODS: One hundred and fifty-seven postmenopausal women with advanced breast cancer were enrolled and randomly assigned to receive letrozole or fadrozole in a multicentre, randomised double-blind trial in Japan. One hundred and fifty-four eligible patients were treated with either letrozole 1.0 mg once daily (n = 77) or fadrozole 1.0 mg twice daily (n = 77), for a minimum of 8 weeks. RESULTS: Letrozole showed a significantly higher overall objective response rate [complete response (CR) + partial response (PR)] than fadrozole (31.2% and 13.0%, respectively; P = 0.011, Fisher's exact test). Clinical benefits defined as CR, PR and stable disease (no change in status for more than 24 weeks) were also higher in patients treated with letrozole (50.6%) than fadrozole (35.1%). Letrozole was significantly superior to fadrozole in terms of the dominant lesion in soft tissue, bone and viscera (P = 0.011, stratified Mantel-Haenszel test). Median time to progression was 211 days in the letrozole group and 113 days in the fadrozole group with no significant difference (P = 0.175, log-rank test). Letrozole markedly reduced the estradiol, estrone and estrone sulfate levels in peripheral blood within 4 weeks. The suppressive effect of fadrozole on these hormone levels was insufficient. Adverse drug reactions were observed in 35.9% of the patients treated with letrozole and in 39.5% of those treated with fadrozole with no significant difference between the two groups (P = 0.74, Fisher's exact test). Most of the adverse drug reactions were rated as grade 1 or 2. CONCLUSIONS: The results show letrozole at a dose of 1.0 mg once daily to be more effective in treating postmenopausal women with advanced breast cancer than fadrozole at 1.0 mg twice daily, with similar safety and tolerability profiles.

Effect of the potent aromatase inhibitor fadrozole hydrochloride (CGS 16949A) in postmenopausal women with breast carcinoma.

BACKGROUND: Fadrozole hydrochloride (CGS 16949A) is a highly potent, nonsteroidal aromatase inhibitor that significantly lowers estrogen levels in postmenopausal women and can be effective therapy for patients with advanced hormone-dependent breast carcinoma. Circulating estradiol, estrone, and estrone sulfate are reduced to undetectable levels within weeks of the initiation of therapy. Before this study, it was not known whether this decrease in serum estrogen levels results in altered parameters associated with cardiovascular disease. The authors examined the levels of several critical blood parameters that are important to cardiovascular risk for heart disease and thromboembolic disorders in patients treated with fadrozole. METHODS: Cholesterol, triglyceride, low density lipoprotein (LDL), high density lipoprotein (HDL), very low density lipoprotein (VLDL), antithrombin III, protein C, protein S, and fibrinogen were serially measured in 21 postmenopausal women with advanced breast carcinoma treated with various doses of fadrozole (1.8 mg/day, n=3; 2.0 mg/day, n=13; 4.0 mg/day, n=5) over 3-24 months (mean, 15.8 months). A repeated measure analysis of variance was applied to each cardiovascular variable to assess changes in the response over time. Analyses were performed separately for each dose group and were also pooled over the dose groups. RESULTS: There was no statistically significant change over time in lipid parameters, namely, total cholesterol (P=0.57), triglyceride (P=0.27), LDL (P=0.99), HDL (P=0.30), and VLDL (P=0.43), over the 24 months of therapy. There were also no significant changes in coagulation factors, namely, antithrombin III (P=0.41), protein C (P=0.49), or protein S (P=0.31), over the 24 months. However, an increase in fibrinogen that occurred over time did reach statistical significance (P=0.011). CONCLUSIONS: With the exception of acute phase reactant fibrinogen, this study did not identify an increase in parameters associated with cardiovascular disease in women treated with fadrozole, a potent aromatase inhibitor.

Fadrozole hydrochloride in postmenopausal patients with metastatic breast carcinoma.

BACKGROUND: Fadrozole hydrochloride (CGS-16949A) belongs to the class of aromatase inhibitors that lowers circulating estrogen levels by inhibiting the conversion of androgens to estrogens, thereby causing tumor regression in patients with breast carcinoma. METHODS: This was a prospective, randomized, Phase II study of fadrozole hydrochloride in postmenopausal patients with metastatic breast carcinoma. The three treatment groups received, respectively, fadrozole hydrochloride 0.6 mg three times daily, 1 mg twice daily, and 2 mg twice daily orally. RESULTS: Fifty-six patients were entered on protocol and 54 were eligible (2 patients were perimenopausal). Eight patients had received no prior therapy, 15 patients had received prior hormonal therapy, 5 patients had received prior chemotherapy, and 28 patients had received both. After 12 weeks of treatment, 2 complete and 3 partial responses were observed. Forty patients continued treatment beyond 12 weeks, and 3 additional responses were achieved. Thus, 8 of 56 patients responded (14% overall response rate). Responses did not appear to be dose-related. The median duration of response was 36 months (range, 8-45 months). Subjective toxicity was mild to moderate and appeared more frequent on the 2 mg twice daily dosing schedule. No objective toxicity in laboratory parameters was observed. No patient had severe or life-threatening toxicity. Fadrozole hydrochloride plasma concentrations (obtained every 2 weeks for 12 weeks) appeared to be dose-dependent and noncumulative. CONCLUSIONS: This study confirms modest activity of fadrozole hydrochloride in a heterogeneous group of patients with breast carcinoma treated at three different dose levels.

A randomised study of CGS 16949A (fadrozole) versus tamoxifen in previously untreated postmenopausal patients with metastatic breast cancer.

BACKGROUND: Fadrozole, a potent, highly specific inhibitor of aromatase activity, has only been used as second-line therapy in treatment of post-menopausal women with advanced breast cancer. A prospectively randomised study was therefore undertaken to compare relative clinical efficacy of fadrozole as first-line treatment to that of tamoxifen. PATIENTS AND METHODS: Eighty postmenopausal women who had not received prior treatment for advanced/metastatic breast cancer were randomised to receive either fadrozole, 1 mg twice daily, or tamoxifen, 20 mg daily. RESULTS: Toxicity was not statistically different on the two treatment arms. Only mild to moderate toxicity was documented: hot flashes in 37%, headaches in 6.5%, mild fatigue in 2.6%. There were also no statistically significant differences in objective response rates, survival or time to treatment failure (TTF). Objective response rate on fadrozole was 50% (complete response (CR) 8.3% and partial response (PR) 42%). On tamoxifen objective response was 44.7% (CR 21% and PR 24%). Median TTF was 4.9 months on fadrozole and 5 months on tamoxifen. Median survival was 22.7 months on fadrozole and 27.5 months on tamoxifen. CONCLUSION: While response rates, survival and TTF were not statistically significantly different, there were more complete responses on tamoxifen and duration of objective response (CR + PR) was significantly longer in the patients treated with tamoxifen.

First-line fadrozole HCI (CGS 16949A) versus tamoxifen in postmenopausal women with advanced breast cancer. Prospective randomised trial of the Swiss Group for Clinical Cancer Research SAKK 20/88.

BACKGROUND: In a phase III randomized trial, we compared the effectiveness and tolerability of fadrozole (CGS 16949A), a non-steroidal aromatase inhibitor, to tamoxifen as first-line endocrine therapy in postmenopausal women with advanced breast cancer. PATIENTS AND METHODS: Two hundred twelve eligible patients were randomized to receive tamoxifen 20 mg daily, or fadrozole 1 mg twice daily orally until disease progression or the advent of undue toxicity. The treatments were to be discontinued upon disease progression. RESULTS: Prognostic factors were well balanced between the treatment groups, except for sites of metastatic disease. Fadrozole-treated patients had significantly more visceral, especially liver, involvement and less bone-dominant disease. Response rates for fadrozole and tamoxifen were similar, 20% and 27% (95% Confidence Limits (CL): 13%-29% and 21%-35%), respectively. Time to treatment failure was longer in patients randomized to tamoxifen (8.5 months for tamoxifen vs. 6.1 months for fadrozole), but did not reach statistical significance after adjustment for prognostic factors (P = 0.09). Fadrozole, for which a significantly lower percentage of clinically relevant toxic effects (WHO toxicity grade > or = 2) was recorded (27% vs. 13%, respectively; P = 0.009), was better tolerated than tamoxifen. Severe cardiovascular events including 3 fatalities were seen only in patients treated with tamoxifen. Eighty-two patients crossed over to tamoxifen and 66 patients to fadrozole. Crossover endocrine therapy led to response or stable disease in 64% of the patients. The overall survival times of the two treatment groups were similar. CONCLUSIONS: Fadrozole and tamoxifen showed similar efficacy as first-line treatments in postmenopausal patients with advanced breast cancer. Fadrozole was significantly better tolerated and may therefore be an appropriate alternative to tamoxifen, especially for patients predisposed to thromboembolic events.

Fadrozole HCL (CGS-16949A) versus megestrol acetate treatment of postmenopausal patients with metastatic breast carcinoma: results of two randomized double blind controlled multiinstitutional trials.

BACKGROUND: Breast cancer patients with prior response to endocrine therapy achieve subsequent benefit from additional endocrine therapies. The efficacy and safety of an aromatase inhibitor, fadrozole HCL, were compared with megestrol acetate in post menopausal patients who had disease progression after receiving antiestrogen therapy either for metastatic disease or as adjuvant therapy. METHODS: In 2 multiinstitutional prospective trials, 683 postmenopausal patients were randomized to receive either fadrozole HCL, 1 mg twice daily, or megestrol acetate, 40 mg 4 times daily, in a double blind fashion after progression on first-line hormonal therapy. Objective response rates, time to progression, survival and safety of the two regimens were compared. RESULTS: Results of intent-to-treat analyses are presented in this study. No significant differences were detected between the two treatment groups in time to progression, objective response rates, duration of response, and survival in either trial. There were no clinically meaningful differences between the treatment groups in the incidence and severity of adverse experiences, except that weight gain, fluid retention, and dyspnea were observed in more patients in the megestrol acetate group compared with those receiving fadrozole HCL, whereas nausea and vomiting were observed in more patients in the fadrozole HCL group compared with those receiving megestrol acetate. CONCLUSIONS: Fadrozole HCL was as efficacious as megestrol acetate in postmenopausal patients with metastatic breast carcinoma after one hormonal therapy. Adverse experiences were mild with both therapies, but megestrol acetate was associated wiht a higher frequency of weight gain, fluid retention and dyspnea, whereas fadrozole HCL was associated with a higher frequency of nausea and vomiting.

Therapeutic effects of the aromatase inhibitor fadrozole hydrochloride in advanced breast cancer.

The endocrine and therapeutic effects of the aromatase inhibitor fadrozole hydrochloride have been assessed in 80 post-menopausal patients with recurrent breast cancer after tamoxifen failure. Treatment allocation was randomly 0.5, 1.0 or 2.0 mg orally b.d. Eight patients were not assessable for response. All patients were evaluated for toxicity (intent-to-treat analysis). In general, the patients' characteristics were well balanced between the three randomised groups. The endocrine data from this study previously reported suggest a dose-related suppression of oestrone, but not oestradiol or oestrone sulphate. The objective response rate was 17% (95% CI 8.9-27.3%) with no complete responders. Fifteen patients (21%) had stable disease (NC) and 45 patients (63%) had progressive disease (PD). The median duration of objective response was 36 weeks. The median time to treatment failure was 12.7 weeks. The log-rank test showed no statistical difference between the dosage groups. The main adverse events reported were mild to moderate severity: nausea in 11 patients (15%), hot flashes in four (5%) and somnolence in three (4%). No serious adverse events were reported. In conclusion, fadrozole is a clinically active aromatase inhibitor with a low incidence of side-effects and phase III clinical trials in post-menopausal women are currently under way.

[Phase II study of CGS16949A, a new aromatase inhibitor--a dose finding study].

A dose finding phase II study of a novel aromatase inhibitor CGS16949A was performed in postmenopausal patients with advanced breast cancer. The daily dose of 1 mg (0.5 mg b.i.d.), 2 mg (1 mg b.i.d.) or 4 mg (2 mg b.i.d.) CGS16949A was administered orally for 8 weeks or more on dose escalation schedule. The response rates (CR+PR) in the evaluable cases were 13.6%, 22.0% and 13.3% in 1 mg/day group (1 mg group), 2 mg/day group (2 mg group) and 4 mg/day group (4 mg group), respectively. There was no statistically significant difference in the response rates among the three treatment groups. Median time to the onset of PR was 99, 113 and 114 days in 1 mg, 2 mg and 4 mg group, respectively, and the median duration of response was 276 days, 391 days and 277 days in 1 mg, 2 mg and 4 mg group, respectively. Five patients in each treatment group showed prolonged stabilization of disease ("long NC", lasting > or = 6 months). Median durations of stabilization were 223 and 241 days in 2 and 4 mg group respectively. The incidence of adverse effects were 11.9%, 7.5% and 13.0% in 1 mg, 2 mg and 4 mg group respectively, and 30 out of 33 symptoms (90.9%) were of mild. Laboratory abnormalities were observed in 12.2%, 22.9% and 23.8% in the respective groups of 1, 2 and 4 mg, and no patient experienced clinical symptoms related to these changes. Plasma estradiol concentration at one month after initiation of the treatment decreased significantly in comparison with pretreatment levels, and was slightly exceeding the limit of detection. Plasma cortisol was not changed. As shown in this results, CGS16949A showed sufficient efficacy and good tolerability in postmenopausal patients with advanced breast cancer. It was considered that the optimal dose in clinical use judged as 2 mg/day.

[Clinical evaluation of CGS16949A in advanced or recurrent breast cancer--a multi-institutional late phase II clinical trial].

A multi-institutional late-phase II clinical trial of CGS 16949A was conducted at the dose of 1 mg twice daily in postmenopausal patients with advanced or recurrent breast cancer. Seventy patients entered into the study; 65 were eligible and 53 were complete cases. There were 3 CR, 11 PR, 10 long-NC, 14 NC and 25 PD with an overall response rate of 22.2% in 63 evaluable cases. The median period of overall duration of responses was 327.5 days. There were 22 cases that drug was found useful or better, and global usefulness rate was 33.8%. Forty six (76.7%) of patients experienced no side effects in this therapy. Grade 2 toxicities included anorexia (1 pt.), feeling of distension of abdomen (1 pt.), vomiting (1 pt.), fatigue (1 pt.), and only one patient experienced Grade 3 toxicity (anorexia). Grade 2 laboratory abnormalities were confirmed in two patients; one with elevated gamma-GTP and another with elevated LDH, and both were in the absence of liver metastasis. From these results, it is concluded that CGS16949A seemed to be a useful hormonal agent in the treatment of postmenopausal breast cancer.

The effect of food on the relative bioavailability of fadrozole hydrochloride.

The effect of food on the pharmacokinetic disposition of fadrozole hydrochloride was evaluated in nine healthy male and female volunteers. Single 12 mg doses of fadrozole were orally administered to subjects immediately following a standardized meal or after fasting for 12 h, in a randomized crossover design. No statistically significant treatment differences were detected for the pharmacokinetic parameters AUC and half-life. Cmax was significantly reduced by 15% for the fed treatment relative to the fasted treatment, and tmax was delayed by 39%. These findings indicate that the concomitant ingestion of food with fadrozole delays the gastric emptying and/or absorption of fadrozole, but has no effect on the extent of absorption.