Targeted therapies are a new type of medication that acts against one or more specific molecular targets characterising a subtype of lung cancer. This new frontier of research gives physicians the ability to tailor cancer treatment for more effective and potentially less harmful outcomes. These therapies target specific biological differences between cancer cells and normal cells to allow the selective destruction of the proliferating abnormal cells without damaging healthy cells. Many targeted therapies are used in combination with chemotherapy.
Epidermal Growth Factor Receptor (EGFR) inhibitors are one type of targeted therapy used to treat some lung cancers. The information on this page discusses targeted therapies in general and EGFR inhibitors in more detail below.
How targeted therapies work
Each type of targeted therapy has a specific mechanism of action that interferes with cancer cell growth and reproduction during the development, growth and spread of cancer cells. Targeted therapies affect the ability of cancer cells to grow, multiply, repair and/or communicate with other cells but have few effects on normal cells, which reduces treatment side effects. These therapies can act against one or more specific molecular targets, such as a protein, receptor, enzyme, or the formation of new blood vessels requested for the growth of the tumour. Others are based on the genetic make-up displayed by the cancer cells. Many of these therapies focus on proteins that are involved in the cell signalling process. By blocking the signals that tell cancer cells how to continuously grow and divide, targeted therapies can stop their growth and division
Depending on the subtype of your lung cancer, a targeted therapy may provide the best treatment option. This type of treatment may be recommended by your multidisciplinary team after your pathology and imaging tests have been analysed. How targeted therapies are used? Targeted therapies can be used alone, in combination with other targeted therapies, or in combination with other cancer treatments such as chemotherapy or radiotherapy.
How targeted therapies are used?
Targeted therapies can be used alone, in combination with other targeted therapies, or in combination with other cancer treatments such as chemotherapy or radiotherapy.
Most of these therapies are available as pills and can be administered orally. This is a convenient way to receive cancer treatment with less impact on your quality of life. Other agents are given by intravenous infusion. The way the targeted therapy is given depends on the type of drug and its mechanism of action.
Many targeted therapies are still in the preclinical (laboratory) testing stage, some are available within clinical trials (testing in humans), and others have been approved for clinical use.
Epidermal Growth Factor Receptor inhibitor (EGFR) treatment
EGFR inhibitors are one type of targeted therapy used to treat some lung cancers. Advancements in modern molecular biology have greatly increased our understanding of how the body functions at the cell level and how this affects health and disease. While cell growth is essential for maintaining healthy cells and tissues, we now know that cell growth becomes dysfunctional in some diseases, such as cancer.
Cells require control mechanisms, such as growth factors, to ensure normal growth and function occurs in individual cells and tissues. Cells produce growth factors, which bind to growth factor receptors on the surface of nearby or distant cells within the body, triggering a response within those cells. The response could be a range of activity, such as cell division (reproduction) or cell death.
Epidermal growth factors (or EGFs) are one of the most important factors in this process. EGF binds to the EGF-receptor (EGFR) found on the cell surface. This receptor is also called the human epidermal growth factor receptor-1 (HER1). When EGF binds to HER1/EGFR, messages are sent into the cell, which may include:
- Cell proliferation (rapid cell growth or reproduction)
- Cell death or cell survival
- The cell’s ability to pass into other structures e.g a blood vessel wall
- Activation of new blood vessel growth (called angiogenesis)
Healthy HER1/EGFR function:
HER1/EGFR is found in many normal tissue types, including cells of the bones, muscle, blood vessels, skin, nervous system and sensory organs. It is vital for cell reproduction (proliferation) and development, and is very important in the growth of human embryos. The key to its functioning properly is that it is very carefully controlled to regulate cell numbers – not too many and not too few.
HER1/EGFR role in cancer:
We now know that HER1/EGFR is also present in many cancer tumours. In non-small cell lung cancer, HER1/EGFR is found in 40-80% of tumour cells. This increased presence of HER1/EGFR causes an increase (or uncontrolled amount) of messages to the cells, resulting in the uncontrolled and excessive growth that is seen in tumour cells.
Drugs targeting HER1/EGFR:
Two drugs (erlotinib and gefitinib) are now available which block HER1/EGFR. Although they have a similar target, these drugs have important differences between them, such as in their chemical structure, how they are administered and their dosage.
Common side effects seen during treatment with EGFR include:
- loss of appetite
- difficulty in breathing
- mouth irritation
- hair loss
- eye irritation
A healthcare professional, such as a medical oncologist, will be able to provide more information on these drugs, which are proving important in the treatment of cancer.
To view our DVD chapter on Targeted Therapies – click here