What is targeted therapy?

Targeted therapy is a treatment that uses medicines to kill cancer cells or slow their growth. These medicines target certain parts of some cancer cells. They change the ability of the cancer cells to grow and survive. This can block the growth and spread of cancer cells while limiting damage to healthy cells.

Your cancer cells must be tested for genes, proteins, and other factors before targeted therapy is used. This is so the right medicine can be used.

When might targeted therapy be used for soft tissue sarcoma?

Targeted therapy is used for advanced (late-stage) soft tissue sarcoma. It is used to try to stop the cancer from growing any further or to shrink it.

These medicines may be used in cases where the cancer:

• Has already been treated with chemotherapy

• Has spread (metastasized)

• Has come back (is recurring)

• Can’t be removed by surgery

Targeted therapy can’t cure soft tissue sarcoma. But it can help to control and slow its growth.

What types of targeted therapy medicines are used to treat soft tissue sarcoma?

• Tyrosine kinase inhibitors (TKIs)

• Histone methyltransferase (HMT) inhibitors

• Neurotrophic tyrosine receptor kinase (NTRK) inhibitors

Tyrosine kinase inhibitors (TKIs)

These medicines block certain signals in cancer cells. This stops chemical reactions that are needed for cells to grow and divide. TKIs used for soft tissue sarcoma include:

• Pazopanib. This medicine may be used after other medicines have been tried. It works by blocking proteins that the tumor needs to create new blood vessels. Without new blood vessels, the tumor can’t grow.

• Imatinib. This medicine may be used to treat gastrointestinal stromal tumors (GISTs). It may be given before surgery. This can shrink a GIST so that it can be taken out by surgery more easily. It may also reduce the risk of a GIST recurring.

• Sunitinib. This medicine may also be used to treat GISTs. It works by stopping chemical reactions that help the cell to grow and divide. It can also help prevent the tumor from forming new blood vessels.

• Regorafenib. This may be used after imatinib and sunitinib have been tried. It may be used for a late-stage GIST that can’t be treated with surgery. It may help to reduce the tumor. Or to keep it from growing.

Histone methyltransferase (HMT) inhibitors

These medicines work by blocking certain enzymes in some types of cancer cells. These enzymes help with cell division. Blocking them stops cancer cells from growing.

HMT inhibitors used for soft tissue sarcoma include:

• Tazemetostat. This medicine attacks a protein called EZH2 that helps certain cancer cells to grow. This medicine can help shrink epithelioid sarcomas that are too big to be removed by surgery. Or it can help to slow down their growth.

Neurotrophic tyrosine receptor kinase (NTRK) inhibitors

NTRK inhibitors work by targeting soft tissue sarcoma cells that have the NTRK fusion gene.

When a cell has a fusion gene, it means a change (mutation) has occurred. In this case, a part of the chromosome that has the NTRK gene comes loose. It attaches (fuses) to a gene on another chromosome. NTRK fusion genes help create TRK fusion proteins. These proteins may help cancer cells to grow.

NTRK inhibitors that treat soft tissue sarcoma include:

• Larotrectinib

• Entrectinib

• Repotrectinib

These medicines may be used when:

• The cancer has spread

• Surgery is not advised

• No other treatment options exist

How is targeted therapy given for soft tissue sarcoma?

Before treatment starts, you’ll meet with a medical oncologist. This is a doctor who specializes in treating cancer with medicines. They will discuss your treatment choices with you and explain what you might expect.

The targeted therapy medicines used for soft tissue sarcoma are given as tablets or capsules.

What are possible side effects of targeted therapy?

Side effects of targeted therapy will depend on which medicine you're taking. Ask your doctor for more details about possible side effects. Tell your provider about any changes or side effects you have. There are often things that can be done to help you feel better. In most cases, side effects start going away within a few weeks after treatment ends.

Possible side effects from targeted therapy for soft tissue sarcoma can include:

• Upset stomach (nausea) and vomiting

• Diarrhea

• Feeling tired

• Belly pain

• Loss of appetite

• High blood pressure

• High blood sugar (glucose)

• Muscle and bone pain

Working with your doctor

It's important to know which medicines you're taking. Write down the names of your medicines. Ask your healthcare team how they work and what side effects they might cause.

Ask your doctors what symptoms to watch for. Ask when to call them. For example, many of these medicines can cause diarrhea. You may be told to drink a lot of fluids, not eat high-fiber foods, and call if you have 4 or more loose bowel movements a day for more than 2 days.

Make sure you know what number to call with questions or problems. Ask if there is a different number to call after hours when the clinic is closed.

It may help to keep a diary of your side effects. Write down physical, thinking, and emotional changes. A written list will make it easier for you to remember your questions when you go to your appointments. It will make it easier for you to work with your healthcare team to make a plan to manage your side effects.