Estrogen receptor downregulators, called ERDs for short, block the effects of estrogen in breast tissue. ERDs work in a similar way to SERMs, such as tamoxifen. ERDs sit in the estrogen receptors in breast cells. If an ERD is in the estrogen receptor, there is no room for estrogen and it can't attach to the cell. If estrogen isn't attached to a breast cell, the cell doesn't receive estrogen's signals to grow and multiply. ERDs also:
- reduce the number of estrogen receptors
- change the shape of breast cell estrogen receptors so they don't work as well
There is one ERD available to treat hormone-receptor-positive breast cancer:
- Faslodex (chemical name: fulvestrant)
ERDs keep estrogen from latching onto hormone receptors
Hormone receptors are like ears or antennae on a cell. Estrogen sends signals through the receptors that tell breast cancer cells to grow. Cells with estrogen receptors grow and multiply when estrogen attaches to the receptors. But ERDs like Faslodex break down those receptors so that estrogen can't latch on.