Targeted therapy for thyroid cancer

Targeted therapy 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.

Targeted therapy is sometimes used to treat thyroid cancer. If you have targeted therapy, your healthcare team will use what they know about the cancer and about your health to plan the drugs, doses and schedules.

You may have targeted therapy to:

• treat some types of locally advanced or metastatic thyroid cancer
• treat thyroid cancer that doesn't respond to other treatments or comes back (recurs) after treatment
• relieve pain or control symptoms of advanced thyroid cancer (called palliative therapy)

The following types of targeted therapy may be used to treat thyroid cancer.

Kinases are proteins on the surface of cells that send signals to help cells grow and form new blood vessels. Multikinase inhibitors block the action of different kinases, which helps slow or stop cancer cells from growing or spreading. Multikinase inhibitors are often given daily as a pill by mouth (orally). They are usually given until the disease progresses or the side effects outweigh the benefits of having the treatment.

Sorafenib (Nexavar) or lenvatinib (Lenvima) may be used to treat papillary or follicular (including Hurhtle cell) thyroid cancer.

Vandetanib (Caprelsa) or cabozantinib (Cabometyx) may be used to treat medullary thyroid cancer.

Some thyroid cancers, such as papillary and follicular, have certain changes in the RET gene. These changes cause the cancer cells to make excess RET kinase protein, which helps them grow. RET inhibitors work by attacking the RET protein. RET inhibitors are often taken by mouth.

RET inhibitors used to treat thyroid cancer include:

• selpercatinib (Retevmo) for medullary, anaplastic or advanced papillary or follicular thyroid cancers that have mutations of the RET gene
• pralsetinib (Gavreto) for medullary thyroid cancer

Some thyroid cancers have mutations in the NTRK genes that help cancer cells grow. NTRK inhibitors work to target and disable abnormal proteins made by NTRK genes. NTRK inhibitors are taken by mouth.

NTRK inhibitors used for anaplastic, papillary or follicular thyroid cancer include:

• larotrectinib (Vitrakvi)
• entrectinib (Rozlytrek)

Some anaplastic thyroid cancers have changes in the BRAF gene. The MEK gene works together with the BRAF gene so drugs that block MEK can also help treat cancers with changes in the BRAF gene.

BRAF and MEK inhibitors used to treat thyroid cancer include:

• dabrafenib (Tafinlar)
• trametinib (Mekinist)

Side effects of targeted therapy will depend mainly on the type of drug or combination of drugs, the dose, how it's given and your overall health. Tell your healthcare team if you have side effects that you think are from targeted therapy. The sooner you tell them of any problems, the sooner they can suggest ways to help you deal with them. Talk to your doctor or pharmacist about what side effects to expect.

Multikinase inhibitors can cause fatigue, skin rash, loss of appetite, diarrhea, nausea and high blood pressure. They can also cause pain, tingling, numbness, redness and scaling or shedding of skin on the hands and feet (called hand-foot syndrome) or tumour lysis syndrome.

RET inhibitors can cause dry mouth, diarrhea, constipation, high blood pressure, fatigue, swelling in the hands or feet, skin rash, high blood sugar levels, low white blood cell count and low blood platelets.

NTRK inhibitors can cause dizziness, fatigue, nausea, vomiting, constipation, weight gain and diarrhea.

BRAF and MEK inhibitors can cause skin changes, rash, itching, sun sensitivity, headache, fever, chills, joint or muscle pain, fatigue, cough, hair loss, nausea, diarrhea and high blood pressure.

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

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