Children's Cancer

Targeted therapy includes a range of treatments that target the genes, proteins or tissues that make cancer cells different from normal cells, or that contribute to cancer cell growth. Targeted therapies work differently from standard chemotherapy.

Targeted therapy can include treatments that:

• switch off the genes that tell cancer cells to grow
• switch on the genes that tell cancer cells to die
• deliver toxic substances directly to the cancer cells to destroy them
• alter cells within the body, so they destroy cancer cells.

Targeted therapy is a form of personalised medicine. This means the doctors look at your child’s genes, proteins or cell processes, and try to find treatments that will work best. This requires genetic or molecular testing, which is usually done with a blood test or a biopsy. Your child and your child’s cancer need to match a targeted treatment for it to be an option for your child.

Targeted therapies are providing new ways to treat cancer. However, targeted therapies have some limits:

• If your child does not have the target gene or protein, the therapy will not work.
• If your child does have the target gene or protein, it does not guarantee that the treatment will work.
• The cancer may become resistant to the treatment. This means that targeted therapy may work at first but then stop working.

Doctors usually use targeted therapy in combination with other treatments, such as radiation therapy, chemotherapy or surgery. In some cases, targeted therapy is an option after other treatments haven’t worked.

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Types of targeted therapy

Targeted therapy includes:

• monoclonal antibodies (a type of immunotherapy)
• small molecule therapy
• chimeric antigen receptor T-cell (CAR-T) therapy (another type of immunotherapy).

Monoclonal antibodies

Monoclonal antibody therapy is a type of immunotherapy. The antibodies attach to a target on the outside of the cancer cell or tissue around the cancer.

Your child will likely get monoclonal antibody therapy intravenously (in a vein).

The therapy may serve different purposes:

• The antibody attaches to a cancer cell. It then acts as a ‘flag’ to your child’s own immune system to destroy that cell.
• The antibody can block growth receptors on the surface of the cancer cell. Then, substances that make the cancer cell divide cannot reach the cancer cell.
• The antibody may have radiation therapy attached to it. This is called radioimmunotherapy. It allows low doses of radiation to be delivered to the cancer cell without affecting healthy cells.
• The antibody may have chemotherapy attached to it, which attaches to the cancer cell. Then the chemotherapy is sent to the cancer cells and not to healthy cells.

Small molecule therapies

Small molecule therapies are medicines that block processes that make cancer cells:

• grow
• survive
• spread to other parts of the body.

Small molecule therapies can include targeting specific growth factors.

Your child will likely get their small molecule therapy as a pill to swallow.

Chimeric antigen receptor T-cell (CAR-T) therapy

CAR-T therapy is a term for a type of immunotherapy that changes your child’s own T-cells so they can attack the cancer cells.

Some of your child’s blood will taken and sent to a laboratory. In the laboratory, your child’s cells will be changed so that they have structures called chimeric antigen receptors on the surface. After growing enough of the new cells, they are injected back into your child. In the body, the cells will replicate and grow. The ‘new’ T cells may be able to find and attack the cancer cells.

The T cells are taken and re-injected intravenously (in a vein).

Currently, CAR-T therapy is only used for some forms of acute lymphoblastic leukaemia (ALL).

Side effects of targeted therapy

Although targeted therapy aims to specifically target cancer cells and not healthy cells, it can still have side effects. Children receiving targeted therapy can have problems with:

• their skin, hair, nail or eyes
• their liver¹
• high blood pressure
• bleeding, blood clotting or wound healing
• their immune system².

Targeted therapies affect each person differently. Your child may experience none, some or many of these problems.

Medicines and other treatments are available to help deal with many of these side effects. Your child’s doctor will discuss these with you.

Some of these side effects seem severe and can be distressing for you and your child. However, the benefits of targeted therapy usually outweigh the risks. Your child’s doctor will discuss the risks and benefits with you.

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References

^{1 & 2} https://www.cancer.gov/about-cancer/treatment/types/targeted-therapies/targeted-therapies-fact-sheet