Personalized Medicine and Molecular Testing

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Personalized Medicine: Targeted Therapies

All cells in your body have the same genetic blueprint that tells them when to grow and when to die. When that blueprint is damaged, those cells can grow uncontrollably, becoming cancer cells. 

Breakthroughs in research have helped us understand that specific changes (mutations, rearrangements, translocations and other alterations) to the genetic code can drive cancer growth. In most cases, these changes to the genetic code are not hereditary and only exist in cancer cells. They can be caused by exposure to cancer-causing agents (such as cigarette smoke or damaging UV light), or are caused by random mistakes in the life cycle of the cell.  

Conventional chemotherapy attacks rapidly growing cells, regardless of what is driving cancer growth. But these treatments are not always effective and have significant side effects. Some lung cancer patients can benefit more from targeted therapies that attack the specific changes driving cancer cells to grow. These treatment options can prolong life, with fewer side effects.

 

Molecular Testing: Matching a Targeted Therapy to the Right Patient

Lung cancers are not all the same, every patient’s cancer is different. That means that cancer cells with different genetic changes may not be affected by a particular targeted therapy. To know whether a patient will respond to a particular targeted therapy, doctors will conduct molecular testing (also called genetic or genomic testing, or profiling) on the tumor, to match patients to the appropriate targeted therapy.

Professional Guidelines state all patients with advanced-stage lung adenocarcinoma should receive molecular testing for EGFR and ALK to match patients to targeted therapy, regardless of clinical history. 
Read a summary of the guidelines here.

FISH staining for EML4-ALK in lung cancer cells. Credit: Dr. Christine Lovly, Vanderbilt University

  • Between 10-35% of non-small cell lung cancers are driven by changes to the Epidermal Growth Factor Receptor (EGFR)EGFR is a normal gene that tells cells to divide and grow to replace old or injured cells in the body. In cancer cells, mutations can cause EGFR to be constantly active, telling cells to divide and grow. EGFR-positive patients have shown a 70% response rate to treatment, lasting longer than chemotherapy responses and with less toxicity.

  • Changes to the Anaplastic Lymphoma Kinase (ALK) gene are present in 3-7% of non-small cell lung cancers. ALK also tells cells to divide and grow. In cancer cells, the ALK gene breaks apart and attaches to another gene (called rearrangement). This causes ALK to be constantly active. ALK-positive patients have shown a 60% response rate to treatment, with less toxicity than chemotherapy.

There are many other specific genes associated with driving cancer growth, and researchers are hard at work developing new drugs to target them. Some of these genes, such as KRAS, can also give us information about whether a tumor will respond well or poorly to other treatments. Other types of lung cancers with specific biomarkers may have additional targeted therapies being developed in clinical trials

 

What are biomarkers? Biomarkers are things that can be measured in the body to give us information about a disease or other condition. ‘Biomarker’ is a broad term that can be applied to a number of things, including genes, proteins, and imaging methods.  In the context of targeted therapies, biomarkers refer to specific genes, or the products of genes (proteins), that indicate whether a patient is likely to respond to a particular treatment. In the context of early detection, biomarkers are proteins or other elements that can tell us if cancer is present.

 

Questions to Ask Your Doctor

  • Should I be tested for the two molecular biomarkers, EGFR mutation and ALK rearrangement? 
  • What were the results of my molecular tests? 
  • What targeted therapies are available to me? 
  • Is the laboratory performing my testing an accredited laboratory?

 

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