Epidermal Growth Factor Receptor inhibitor (EGFR) treatment

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.

Side effects:

Common side effects seen during treatment with EGFR include:

• rash
• diarrhoea
• tiredness
• loss of appetite
• difficulty in breathing
• cough
• infection
• nausea
• vomiting
• mouth irritation
• stomach
• pain
• itchingdry
• skin
• 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.