Targeted Therapy for Basal and Squamous Cell Skin Cancers

As researchers have learned more about some of the changes inside skin cancer cells that help them grow, they have developed newer types of drugs that target these changes. These drugs target parts of skin cancer cells that make them different from normal skin cells.

Targeted drugs work differently from standard chemotherapy (chemo) drugs. They may work sometimes when chemo drugs don’t. They can also have different side effects.

Like chemo and immunotherapy, targeted drugs enter the bloodstream and reach almost all areas of the body, so they can sometimes be helpful against skin cancers that have spread too far to be treated with surgery or radiation.

Doctors are still learning the best way to use these drugs to treat skin cancers.

Hedgehog pathway inhibitors

These targeted drugs can be used to treat some advanced or recurrent basal cell skin cancers (BCCs). Examples include:

• Vismodegib (Erivedge)
• Sonidegib (Odomzo)

It’s very rare for BCCs to reach an advanced stage, but if they do, these cancers can be hard to treat. In most BCCs, the cells have mutations (changes) in genes that are part of a cell signaling pathway called hedgehog. (Cell signaling pathways are how a cell gives instructions from one part of the cell to another, or to other cells.) The hedgehog pathway is crucial for the development of the embryo and fetus and is important in some adult cells, but it can be overactive in BCC cells, helping them grow. These drugs target a protein in this pathway.

These drugs are taken as capsules, typically once a day.

For BCCs that have spread, that have come back after surgery or radiation therapy, or that can’t be treated with surgery or radiation, these targeted drugs can often help shrink tumors or slow their growth.

Side effects of hedgehog pathway inhibitors

Side effects can include muscle spasms, joint pain, hair loss, fatigue, problems with taste, poor appetite and weight loss, nausea and vomiting, itchy skin, diarrhea, and constipation. These drugs can also cause women to stop having their periods.

Because the hedgehog pathway affects fetal development, these drugs should not be taken if someone is pregnant or could become pregnant. It is not known if these drugs could harm the fetus if taken by a male partner. Anyone taking these drugs should use reliable birth control during and for some time after treatment.

EGFR inhibitors

In squamous cell cancer (SCC) of the skin, the cells often have too much of a protein called EGFR on their surfaces, which can help them grow.

Drugs that target the EGFR protein, such cetuximab (Erbitux), have been shown to shrink some SCCs in early studies. Although the evidence for their use so far is limited, they might help some people who aren’t helped by other treatments.

Side effects of EGFR inhibitors can include:

• Skin problems
• Diarrhea
• Mouth sores
• Loss of appetite

Skin problems can include an acne-like rash on the face and chest, which in some cases can lead to skin infections.