Targeted Therapy

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How does targeted therapy work?

Targeted therapy is used to keep cancer from growing and spreading. To become cancer cells, normal cells go through a process called carcinogenesis (car-sin-oh-JEN-eh-sis). Cancer cells may then grow into tumors or reproduce throughout a body system, like blood cancers do. Scientists have learned a lot about the molecules that are part of this process and the signals a cell gets to keep this process going.

Targeted therapy disrupts this process. The drugs target certain parts of the cell and the signals that are needed for a cancer to develop and keep growing. These drugs are often grouped by how they work or what part of the cell they target.

Enzyme inhibitors

Our bodies produce many types of enzymes, which are special proteins that help control many of the things our cells do. When most people think of enzymes, the first ones that come to mind are those that help digest (break down) the food we eat. But some enzymes serve as signals for cancer cells to grow.

Some targeted therapies block (inhibit) enzymes that are signals for cancer cells to grow. These drugs are called enzyme inhibitors. Blocking these cell signals can keep the cancer from getting bigger and spreading. So even if the tumor is not getting smaller, its out-of-control growth has been interrupted. This may give regular chemo a better chance to work. Slowing or stopping out-of-control growth may also help people live longer, even without adding other drugs.

Enzyme inhibitors may be called different names based on the enzymes they block:

  • Tyrosine kinase inhibitors (tie-ruh-seen kine-ace)
  • mTOR inhibitors
  • Proteosome inhibitors (pro-tee-us-ohm)
  • Growth factor inhibitors
  • Signal-transduction inhibitors (trans-duck-shun)
  • Multi-targeted kinase

A multi-targeted kinase drug blocks many different enzymes. It may also be called a multikinase inhibitor.

Apoptosis-inducing drugs

Some targeted therapies change proteins within the cancer cells and cause the cells to die. These are called apoptosis-inducing drugs. (Apoptosis, pronounced a-pop-TOE-sis, is the medical word for cell death. These drugs cause or induce cell death.) Many cancer treatments, including radiation and chemo, cause cell changes that lead to apoptosis. But targeted drugs in this group are different, because they are aimed right at the parts of the cell that control whether cells live or die.

Angiogenesis inhibitors

Angiogenesis (an-jee-oh-JEN-uh-sis) is the process of making new blood vessels. In most cases, this is a normal, healthy process. As the human body grows and develops, it needs to make new blood vessels to get blood to all of its cells. As adults, we don’t have quite the same need for making new blood vessels, but there are times when angiogenesis is still important. New blood vessels, for instance, help the body heal wounds and repair damage.

But in a person with cancer, this same process creates new blood vessels that give a tumor its own blood supply. This blood brings nutrients that allow the cancer to grow and spread. Angiogenesis inhibitors target and stop (or inhibit) this process—they stop the tumors from making new blood vessels. This helps cut off the tumors’ blood supply, and without blood, tumors can’t grow.

Many of these drugs work by blocking vascular endothelial (vas-ku-ler end-oh-THEE-lee-al) growth factor, also called VEGF. VEGF is a family of protein growth factors made by some tumors. The VEGF proteins can attach to the VEGF receptors of blood vessel cells. This causes new blood vessels to form around the tumors. Blocking this process prevents angiogenesis, which would form new blood vessels to feed tumors so they could grow.

Last Medical Review: 07/12/2013
Last Revised: 07/12/2013