Anastrozole, 1 and 10 mg once daily, is well tolerated and as effective as megestrol acetate in the treatment of postmenopausal women with advanced breast cancer who progressed following tamoxifen treatment. Moreover, anastrozole therapy avoids the weight gain associated with megestrol acetate treatment.

Arimidex is a potent and selective aromatase inhibitor undergoing evaluation as a treatment for postmenopausal women with advanced breast cancer. Studies to determine the pharmacology of Arimidex were conducted in both animals and humans. In animals, Arimidex was selective for the aromatase enzyme, elicited maximal activity at about 0.1 mg/kg, did not interfere with steroid hormones produced by the adrenal glands, and, at a dose of 1 mg/kg, had no detectable pharmacologic activity other than aromatase inhibition. Absorption of ZD1033, the active component of Arimidex, was rapid and virtually complete after oral administration to animals. ZD1033 was extensively metabolized in animals after oral administration; the metabolites were excreted predominantly in urine. The pharmacodynamic, pharmacokinetic, and safety profiles of single and multiple daily doses of Arimidex were determined in humans. Doses of 1 to 10 mg of Arimidex suppressed estradiol to the maximum degree measurable. Arimidex had no clinically significant effects on key enzymes that regulate cortisol and aldosterone biosynthesis. Absorption of ZD1033 was rapid, with maximum plasma concentrations occurring within 2 hours after oral administration. Plasma concentrations of ZD1033 rose with increasing doses of Arimidex. The elimination half-life of ZD1033 in humans ranged from 30 to 60 hours. Urinary excretion accounted for a small percentage of each dose. A 3- to 4-fold accumulation of ZD1033 in plasma occurred after daily administration of 3-, 5-, or 10-mg doses. Arimidex was well tolerated. Phase III studies are under way to determine the efficacy and safety of Arimidex in postmenopausal women with advanced breast cancer.

Key Points Erwinia asparaginase was granted FDA approval in November 2011 for use in patients with allergic reactions to E coli-derived asparaginase. Erwinia asparaginase 25 000-IU/m2 for 6 intramuscular doses M/W/F can be substituted for a single dose of pegaspargase.

Pubertal gynecomastia is thought to result from transient imbalances between estrogen and androgen concentrations. Anastrozole (ARIMIDEX), a potent and selective aromatase inhibitor, decreases estrogen and increases testosterone concentrations in pubertal boys. The safety and efficacy of anastrozole for the treatment of pubertal gynecomastia were evaluated. In a randomized, double-blind, placebo-controlled study of 80 boys, aged 11-18 yr, with pubertal gynecomastia that had not reduced over a 3-month interval, subjects received either anastrozole (1 mg) or placebo once daily for 6 months. A response was defined as a 50% or greater reduction in the calculated volume of both breasts combined using ultrasonography measurements. A comparison of response rates was performed using logistic regression analysis. Secondary end points included changes in serum hormone concentrations. The percentage of patients with a response was 38.5% for the anastrozole group and 31.4% for the placebo group (odds ratio, 1.513; 95% confidence interval, 0.496-4.844; P = 0.47). At 6 months, the median percent change in the testosterone/estradiol ratio was 166% for the anastrozole group and 39% for the placebo group. Anastrozole treatment was well tolerated. In patients with pubertal gynecomastia, no significant difference in the percentage of patients with a 50% or greater reduction in total breast volume, as calculated from ultrasonography measurements, was demonstrated between the anastrozole and placebo groups.

Background L‐Asparaginase is an integral component of standard chemotherapy regimens for the treatment of acute lymphoblastic leukemia (ALL). Clinical hypersensitivity, a common reason for treatment discontinuation, has been reported in 10–30% of patients receiving Escherichia coli‐derived asparaginase. After hypersensitivity, E. coli‐derived asparaginase should be discontinued and an alternative asparaginase preparation, such as asparaginase Erwinia chrysanthemi, may be initiated. We conducted a compassionate‐use study to collect additional safety information on asparaginase Erwinia chrysanthemi and to support FDA approval of the product. Procedure Patients with ALL or lymphoblastic lymphoma (LBL; N = 1368) who developed a hypersensitivity reaction (grade ≥2) to an E. coli‐derived asparaginase participated in this trial. The recommended asparaginase Erwinia chrysanthemi dose was 25,000 IU/m2 three days per week (Monday/Wednesday/Friday) for two consecutive weeks for each missed pegylated E. coli‐derived asparaginase dose and 25,000 IU/m2 for each missed nonpegylated asparaginase dose for the completion of their planned asparaginase treatment. Results Adverse event reports and/or case report forms were completed for 940 patients. The most common adverse event (AE) was hypersensitivity (13.6%). Eighteen patients (1.9%) died during the study. Most patients (77.6%) completed their planned asparaginase treatment with asparaginase Erwinia chrysanthemi. There was no apparent difference in the incidence of the most commonly reported AEs with asparaginase treatment by age, administration, or disease state. Conclusions This study further established the safety profile of asparaginase Erwinia chrysanthemi in patients with ALL or LBL who had a hypersensitivity reaction to an E. coli‐derived asparaginase. Pediatr Blood Cancer 2014;61:1232–1238. © 2014 Wiley Periodicals, Inc.