The side effects of Targeted cancer therapies

Scientists had expected that targeted cancer therapies would be less toxic than traditional chemotherapy drugs because cancer cells are more dependent on the targets than are normal cells. However, targeted cancer therapies can have substantial side effects.
The most common side effects seen with targeted therapies are diarrhea and liver problems, such as hepatitis and elevated liver enzymes.  Other side effects seen with targeted therapies include:

• Skin problems (acneiform rash, dry skin, nail changes, hair depigmentation)
• Problems with blood clotting and wound healing
• High blood pressure
• Gastrointestinal perforation (a rare side effect of some targeted therapies)

Certain side effects of some targeted therapies have been linked to better patient outcomes.  For example, patients who develop acneiform rash (skin eruptions that resemble acne) while being treated with the signal transduction inhibitors erlotinib (Tarceva®) or gefitinib (Iressa®), both of which target the epidermal growth factor receptor, have tended to respond better to these drugs than patients who do not develop the rash. Similarly, patients who develop high blood pressure while being treated with the angiogenesis inhibitor bevacizumab generally have had better outcomes.
The few targeted therapies that are approved for use in children can have different side effects in children than in adults, including immunosuppression and impaired sperm production.