Targeted therapy for soft tissue sarcoma

Some people with certain types of soft tissue sarcoma have targeted therapy. It uses drugs to target specific molecules (such as proteins) on cancer cells or inside them. These molecules help send signals that tell cells to grow or divide. By targeting these molecules, the drugs stop the growth and spread of cancer cells and limit harm to normal cells. Targeted therapy may also be called molecular targeted therapy.

You may have targeted therapy to:

• stop cancer cells from growing, dividing and spreading
• relieve pain and control other symptoms of advanced soft tissue sarcoma (called palliative therapy)

Your healthcare team will consider your personal needs to plan the drugs, doses and schedules of targeted therapy. You may also receive other treatments.

The following are targeted therapy drugs that may be used to treat soft tissue sarcoma.

Tyrosine kinase inhibitors (TKIs) block chemicals called tyrosine kinases. These chemicals are part of the signalling process within cells. When this process is blocked, the cell stops growing and dividing.

Pazopanib (Votrient) is a TKI drug that may be used to treat soft tissue sarcoma. It targets many different proteins including VEGF (vascular endothelial growth factor), which helps cells form new blood vessels. Pazopanib works by finding and attaching to VEGF and preventing cells from forming new blood vessels that they need to grow.

Pazopanib may be used for some types of advanced soft tissue sarcoma when chemotherapy has already been given or the soft tissue sarcoma has continued to grow within 1 year after treatment. It is taken as a pill once a day.

Imatinib (Gleevec) is another TKI that may also be used to treat soft tissue sarcoma. It targets many different proteins including the KIT protein, which helps cells grow, divide and move around.

Imatinib may be used for:

• unresectable or metastatic gastrointestinal stromal tumours (GISTs)
• unresectable, recurrent or metastatic dermatofibrosarcoma protuberans (DFSP)

Imatinib is taken daily as a pill. There is no standard for how long imatinib is given, but doctors may have you take it for up to 3 years.

Neurotrophic tyrosine receptor kinase (NTRK) inhibitors may be used to treat soft tissue sarcoma.

The NTRK gene tells nerve cells to make a protein that helps them send information about certain bodily sensations. When part of the NTRK gene breaks off and joins with another gene, it is called an NTRK gene fusion. This change causes abnormal proteins called TRK fusion proteins, which may cause cancer cells to grow.

The following drugs may be used to treat soft tissue sarcoma with an NTRK gene fusion. They are given as pills.

• larotrectinib (Vitrakvi)
• entrectinib (Rozlytrek)

Side effects can happen with any type of treatment for soft tissue sarcoma, but everyone’s experience is different. Some people have many side effects. Other people have few or none at all.

Targeted therapy attacks cancer cells but doesn’t usually damage healthy cells, so there are usually fewer and less severe side effects than with chemotherapy or radiation therapy. Chemotherapy and radiation therapy can damage healthy cells along with cancer cells.

If you develop side effects, they can happen any time during, immediately after or a few days or weeks after targeted therapy. Sometimes late side effects develop months or years after targeted therapy. Most side effects go away on their own or can be treated, but some side effects may last a long time or become permanent.

Side effects of targeted therapy will depend mainly on the type of drug, the dose, how it’s given and your overall health. Some common side effects of targeted therapy for soft tissue sarcoma are:

• nausea and vomiting
• muscle and bone (musculoskeletal) pain
• diarrhea
• high blood sugar (glucose) levels
• heart problems
• fatigue
• loss of appetite
• pain in the abdomen
• skin problems, such as a rash

Pazopanib may also cause high blood pressure (hypertension) and hair colour changes.

Tell your healthcare team if you have these side effects or others you think might be from targeted therapy. The sooner you tell them of any problems, the sooner they can suggest ways to help you deal with them.

Details on specific drugs change regularly. Find out more about sources of drug information and where to get details on specific drugs.

Find out more about targeted therapy. To make the decisions that are right for you, ask your healthcare team questions about targeted therapy.