Targeted therapies are drugs that block the growth of cancer by interfering with the molecules involved in tumor growth and spread. This treatment differs from chemotherapy, which targets any rapidly dividing cells, because targeted therapies are designed to interfere with genes and proteins specific to the malignant cancer. Because of this level of specificity, targeted therapies for colorectal cancer tend to have less severe side effects than chemotherapy. However, while targeted therapies have been shown to be helpful in patients with stage IV cancer, they have not been as helpful in patients with stage III cancer.

Download our 3-part book, Your Guide in the Fight, for more in-depth information on your options for targeted therapies for colorectal cancer.

Types of Targeted Therapies for Colorectal Cancer

Angiogenesis Inhibitors

Angiogenesis is a normal process the body undergoes to grow new blood vessels and provide oxygen and nutrients to new cells. Cancer cells also need a blood supply to survive and continue growing. Angiogenesis inhibitors block the growth of blood vessels so that tumors are unable to thrive.

Some angiogenesis inhibitors target the action of vascular endothelial growth factor (VEGF), which signals new blood vessel formation. Other angiogenesis inhibitors target different molecules in the blood vessel formation process.

• Bevacizumab (Avastin®) is a monoclonal antibody used to block the growth and development of blood vessels.
• Bevacizumab-awwb (Mvasi®) is a biosimilar of bevacizumab that received FDA approval in 2017.
• Ramucirumab (Cyramza®) is a monoclonal antibody used to block the growth and development of blood vessels.
• Ziv-aflibercept (Zaltrap®) is a recombinant fusion protein used to block blood vessel development.

Gene Expression Modulators

Gene expression modulators change the specific proteins in cancer cells that control gene expression, and therefore, the function or structure of cancer cells.

Immunotherapies

Immunotherapies attempt to destroy cancer cells by stimulating the immune system. There are two methods by which immunotherapy can signal cancer cell death: The treatment can flag the surface of the cancer cells for destruction, or the treatment can bind to immune cells to strengthen their capability to kill cancer cells. Currently, immunotherapy that targets Pd-1  is only approved for a small subset (5%) of patients with metastatic colorectal cancer. 

Monoclonal Antibodies

Certain types of monoclonal antibodies can deliver toxic molecules themselves. The antibodies carry a toxic molecule, such as a radioactive substance or poisonous chemical, attaches itself to the surface of a cancer cell, and inserts the toxic molecule into the cancer cell. The toxin doesn’t affect healthy cells since the antibody only recognizes specific proteins on the surface of cancer cells.

• Cetuximab (Erbitux®) is a monoclonal antibody that inhibits cell growth for patients without a KRAS or NRAS mutation.
• Panitumumab (Vectibix®) is a monoclonal antibody that inhibits cell growth for patients without a KRAS or NRAS mutation and wild-type RAS metastatic colorectal cancer (mCRC).

Signal Transduction Inhibitors

Signal transduction inhibitors block molecules that signal cancer cells to divide uncontrollably.

• Regorafenib (Stivarga®) is a small molecule drug that inhibits cell growth by interfering with the internal workings of the cell.

What to Expect Before Receiving Targeted Therapies

Targeted therapies can be administered through an IV or orally in pill- or capsule-form. Typically, monoclonal antibodies are administered through an IV. It depends on the drug and how it will be administered to determine whether you can undergo treatment at home or at a medical facility.

Side Effects of Targeted Therapies

Since targeted therapies are designed to have a more focused action, they tend to have less severe side effects when compared to chemotherapies. However, the actual effects and their severity largely depends on the targeted action in question. And since targeted therapies are a relatively new development in cancer treatment, the long-term effects are still being studied.

Skin Problems

Targeted therapies can sometimes cause skin problems over the course of a few days or weeks, such as a rash or other skin changes. These differ from drug allergies, which start within a few minutes or hours of starting the treatment. Any skin problems should be reported to your oncology team before starting any over-the-counter medicines. Possible instances of this side effect include:

• Sunburnt feeling without the appearance of redness or rash
• Photosensitivity
• Rash
• Dry skin
• Red, sore cuticles
• Hand-foot syndrome
• Changes in hair growth
• Changes in hair or skin color
• Changes in and around the eyes

Other Side Effects of Targeted Therapies

Depending on the action of the targeted therapy being used, you may experience the following side effects:

• High blood pressure
• Bleeding or blood clotting problems
• Slow wound healing
• Heart damage
• Autoimmune reactions
• Swelling

Since targeted therapies can sometimes be considered a form of chemotherapy, you may also experience similar side effects such as:

• Nausea and vomiting
• Diarrhea or constipation
• Mouth sores
• Shortness of breath or trouble breathing
• Cough
• Fatigue
• Headache
• Hair loss
• Damage to organs such as the thyroid gland, liver, or kidneys
• Allergic reactions (while getting an IV drug)
• Increased risks of certain infections

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