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Aromatase and its inhibitors in breast cancer treatment--overview and perspective
1Department of Pharmacology, School of Medicine, University of Maryland, Baltimore 21201.
Abstract:
Estrogen has an important role in stimulating the growth of breast carcinomas. Inhibition of estrogen production is therefore a logical treatment strategy. A number of selective inhibitors have been developed against aromatase, a cytochrome P-450 enzyme which catalyzes the rate limiting step in the biosynthesis of estrogens. The mechanisms of the aromatase reaction, current knowledge of the enzyme, and regulation of its expression are discussed as the basis for inhibitor development. Two classes of aromatase inhibitors, steroidal and non-steroidal compounds, are now coming into use. Among the steroid substrate analogues, 4-hydroxyandrostenedione (4-OHA) has been shown to be effective in breast cancer patients with advanced disease and was recently approved for treatment in the United Kingdom. Several different classes of compounds which act as aromatase inhibitors are currently in clinical trials and should provide breast cancer patients with a number of treatment options. Among these are highly potent and selective non-steroidal inhibitors which have recently been found to suppress plasma and urinary estrogens over 95% in breast cancer patients. The potency of these newer aromatase inhibitors provides the opportunity to determine whether complete suppression of estrogen production and action will result in enhanced tumor regression.
Insights
New aromatase inhibitors effectively block estrogen production, offering promising new treatment options for advanced breast cancer. Researchers are evaluating if complete estrogen suppression enhances tumor regression.
Area of Science:
- Endocrinology
- Oncology
- Enzyme Inhibition
Background:
- Estrogen fuels breast carcinoma growth, making estrogen production inhibition a key therapeutic strategy.
- Aromatase, a cytochrome P-450 enzyme, catalyzes the rate-limiting step in estrogen biosynthesis.
- Understanding aromatase mechanisms and regulation is crucial for developing effective inhibitors.
Purpose of the Study:
- To review the mechanisms, knowledge, and regulation of aromatase for inhibitor development.
- To discuss current and emerging aromatase inhibitors for breast cancer treatment.
- To explore the potential of potent inhibitors in achieving complete estrogen suppression for enhanced tumor regression.
Main Methods:
- Review of scientific literature on aromatase enzyme and its inhibitors.
- Discussion of steroidal and non-steroidal aromatase inhibitor classes.
- Analysis of clinical trial data for novel inhibitor efficacy.
Main Results:
- Steroidal inhibitor 4-hydroxyandrostenedione (4-OHA) shows effectiveness in advanced breast cancer.
- Potent non-steroidal inhibitors achieve over 95% suppression of plasma and urinary estrogens.
- Multiple classes of aromatase inhibitors are in clinical trials, expanding treatment options.
Conclusions:
- Aromatase inhibitors are a vital therapeutic approach for estrogen-dependent breast cancers.
- Emerging non-steroidal inhibitors offer high potency and selectivity.
- Further research will determine if complete estrogen suppression improves treatment outcomes.