Combinations of surgery, chemotherapy and precision medicines are increasingly successful ways of treating a greater number of patients with bowel cancer metastases

In 2004, the U.S. Food and Drug Administration (FDA) began to approve precision medicines, also known as personalised, targeted or biological therapies for the treatment of cancer.  These treatments work in a variety of ways, including blocking receptors that send growth and survival signals into cells or engaging the body’s immune system to fight cancer cells and have revolutionised cancer treatment.  
 
Initially, therapies targeted the specific proteins vascular endothelial growth factor (VEGF), but now the latest therapies target multiple growth factors and pathways.  Today, there are three types of antiangiogenic therapies for treating metastatic bowel cancer - antibody, fusion protein, and tyrosine kinase inhibitor - that are available in three lines of therapy.
 
The development of precision medicine is an exciting step in the treatment of metastatic bowel cancer as it may make it possible to destroy cancer cells without damaging other, healthy cells. As a result, precision medicine makes it possible for your oncologist to tailor your treatment program to:
 
  • reduce side effects; 
  • extend survival, and 
  • limit toxicity exposure.
These new treatments may:
  • stop cancer cells from dividing and growing
  • seek out cancer cells and kill them
  • encourage the immune system to attack cancer cells
  • alter the growth of blood vessels into the tumour
There is no simple way of grouping these treatments.  Some are grouped according to the effect they have, for example: drugs that block cancer cell growth (called EGFR inhibitors) or drugs that block the growth of new blood vessels to the tumour (VEGF inhibitors).
 
The epidermal growth factor receptor (EGFR) is a molecule identified on cancer cells that contributes to tumor development and growth.  In about 80% of malignant bowel cancer tumors, EGFR signaling plays a role in the progression of the disease.  EGFR also can cause angiogenesis.  Anti-EGFR treatment targets this receptor to interrupt its signaling and, thus, hinder tumor development.
 
Some of these drugs can also be called monoclonal antibodies because they target specific proteins on cancer cells.  New drugs are being developed which act in different ways and may have multiple modes of action.  
 
Treatment Targeted Therapies

 
 

Chemotherapy and Precision Medicines
 
Sometimes your multi-disciplinary team will decide that surgery is unlikely to be an option for you, or that it could be an option at a later date but further exploration/treatment is needed first.
 
Combinations of surgery, chemotherapy and precision medicines are increasingly successful ways of treating a greater number of patients with bowel cancer metastases.
 
The purpose of these types of treatments is to shrink the tumours down and kill the cancer cells, to either make them dormant, or to bring them to a point where they can be removed with surgery, or safely targeted with other kinds of treatment directly into them.
 
The standard chemotherapy drugs for metastases are the same as the ones used to treat cancer in the bowel (colon or rectum).  They can be given on their own, in different combinations at the same time, or given one after the other, depending on your own particular circumstances.  You may recognise some of the names of the individual drugs: Eloxatin (Oxaliplatin), (Camptosar) Irinotecan, 5-FU (5-fluorouracil) and Xeloda (Capecitabine).
 
These are some of combinations currently being used:

  • FOLFOX (5-FU + Oxaliplatin)
  • FOLFIRI (5-FU + Irinotecan)
  • FOLFOXIRI (5-FU + Oxaliplatin + Irinotecan)
  • XELOX (Capecitabine + Oxaliplatin)
With the exception of the capecitabine capsules, all these drugs are given as infusions.
 
Precision medicines work by interfering with the way individual cancer cells behave so that they cannot thrive or reproduce properly.
 
Used in combination with standard chemotherapy treatments, they can offer a very effective treatment option for some bowel cancer patients.
 
There are currently a number of targeted therapies available for use in Australia to treat advanced (metastatic) bowel cancer.  These include:

  • Avastin (Bevacizumab)
  • Erbitux (Cetuximab)
  • Vectibix (Panitumumab)
  • Stivarga (Regorafenib) 
  • Zaltrap (Aflibercept rch)
Your oncologist will be able to discuss the possibilities for treatment with you, depending on your own particular circumstances.
 
For more information about chemotherapy and precision medicines please refer to Bowel Cancer Australia's Bowel Cancer - Surgery & Treatment and Advanced Bowel Cancer - Surgery & Treatment resources. 
 

Monoclonal Antibody Therapy
  
Monoclonal antibody therapy is a type of precision medicine being used for the treatment of bowel cancer.
 
'Monoclonal' means all one type.  'Antibody' is a protein in your immune system that recognises and attacks foreign substances.
 
Monoclonal antibody therapy uses antibodies made in the laboratory from a single type of immune system cell.  These antibodies can identify substances on cancer cells or normal substances that may help cancer cells grow.
 
So a 'monoclonal antibody' is a treatment designed to recognise and target only one type of foreign substance (e.g. cancer cells).
 
The antibodies attach to the substances and kill the cancer cells, block their growth, or keep them from spreading.  Monoclonal antibodies are given by infusion.  They may be used alone or to carry drugs, toxins, or radioactive material directly to cancer cells.
 
During treatment, your health care team will watch for signs of problems.  Some people get medicine to prevent a possible allergic reaction.  The side effects depend mainly on the monoclonal antibody used.  Side effects may include rash, fever, abdominal pain, vomiting, diarrhoea, blood pressure changes, bleeding, or breathing problems.  Side effects usually become milder after the first treatment.
 
You might want to ask your oncologist these questions before having a precision medicine:

  • What drugs will I have?
  • What will they do?
  • When will treatment start?
  • When will it end?
  • How often will I have treatments?
  • Where will I go for treatment?
  • Will I be able to drive home afterward?
  • What can I do to take care of myself during treatment?
  • How will I know the treatment is working?
  • Which side effects should I tell you about?
  • Will there be long-term side effects?
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