What is the mechanism of action for selective estrogen receptor downregulators (SERDs)?

The mechanism of action for selective estrogen receptor downregulators (SERDs) involves binding to estrogen receptors and inducing their degradation. SERDs are designed to not only bind to estrogen receptors but also promote their destruction, effectively reducing the availability of these receptors for estrogen to bind. This mechanism is particularly valuable in treating estrogen receptor-positive breast cancer, as it leads to decreased estrogen receptor signaling that can promote tumor growth. By degrading the receptors, SERDs lower the overall estrogen-driven activity that can contribute to cancer progression, making them an important therapeutic option in oncology.

The other options provided involve different mechanisms that do not pertain specifically to the action of SERDs. For instance, blocking androgen receptors and inhibiting androgen synthesis relate to the treatment of hormone-sensitive cancers dependent on androgen rather than estrogen. Activating estrogen receptors would contradict the intended action of SERDs, as they aim to reduce estrogenic activity, not enhance it. Understanding these distinctions helps in appreciating the targeted approach of SERDs in breast cancer treatment.