Last couple of years have been fascinating for cancer treatment. New treatments, new research, new therapies. So many advances are we any closer to a cure?
As doctors we are very excited about the personalised treatment targeted therapy offers. It is linked to ‘precision medicine’ that considers individual variability in a person’s genetic work up, environment and lifestyle to arrive at probable treatment options.
It’s an emerging approach and it allows doctors and researchers to predict more accurately which treatment and prevention strategies will work for a particular disease and amongst which groups of people.
This contrasts with a ‘one-size-fits-all’ approach, where individual differences are not considered.
The Ninja At Work
In oncology, precision medicine has started to drive a powerful revolution through the targeted therapy approach.
We can now distinguish between healthy cells and cancer cells and then develop treatment approaches where our drugs kill only cancer cells.
Unlike traditional cancer treatments that destroy both the cancerous cell and its neighboring tissue, targeted therapy uses drugs designed specifically to attack only cancer cells by attaching to or blocking molecular processes that are responsible for cancer development.
Targeted therapy is becoming the focus of anti-cancer research and development both globally and in India. In some ways, it would be correct to say that targeted therapy uses the body’s natural defense mechanisms at a cellular level to control the rogue behavior of cancer cells.
Types of Targeted Therapy
Various forms of targeted treatments have been approved for use in cancer therapy.
Stop Them on Their Track
Angiogenesis inhibitors
Angiogenesis is the process of new blood vessel formation and plays a big role in how cancer cells proliferate in a tumour. Angiogenesis inhibitors are molecules that interfere with this process so that cancer growth can be blocked.
Self Defense
Immunotherapy
This approach uses the growing understanding of how the body’s immune system responds to an external ‘invasion’. But cancer cells can evade the immune system and continue to multiply. Immunotherapy explores new ways of reversing this process and now we have drugs that can help us do this.
Bottom line, our body’s immune system can now be used to fight cancer.
Fight Poison with Poison
Monoclonal antibodies that deliver toxic molecules
This form of targeted therapy involves the use of monoclonal antibodies bound to toxic molecules such as radioactive substances or a poisonous chemical. On recognizing a cancerous cell, the monoclonal antibody releases the toxin which destroys the target cell. The ‘toxin’ does not affect cells that lack the target for the antibody, i.e. the body’s healthy cells.
Block the Good Bad Boys
Growth signal inhibitors
Normally, growth factors stimulate cellular growth, proliferation, healing and cellular differentiation. But when there are too many of these good guys around, they contribute to the growth and division of cancer cells. The inhibitors help in finding molecules that can block these growth signals and prevent cancer cell division.
Fixing the Genes
Gene therapy
About half of all cancers have a mutated p53 gene which prevents tumour cells from self-destructing. Investigators are currently trying to genetically introduce a normal 53 gene into cancer cells to promote their destruction.
Depending on the type of cancer, the ‘targets’ for treatment vary. In the case of lung cancer, we now have targeted treatments in the form of oral medication which have fewer side effects compared to chemotherapy.
So how do physicians decide which patients are eligible for targeted therapy?
Well, there’s a specific FDA-set criteria such as: the cancer does not respond to other therapies, the cancer has spread to other organs, its location causes it to be inoperable, or the patient has some specific onco-characteristics that can be treated by targeted therapy.
The progress we have made in targeted therapies has helped us develop advanced treatment regimes, which have been steadily delivering improved patient outcomes.
Research is ongoing to develop more targeted drugs as we discover suitable ‘targets’ in cancer cells. As we move forward we are likely to see multiple approaches working side by side.
Some of these could come from a greater refinement in existing protocols such as chemotherapy and radiation. Some could come from learning to more effectively combine the old with the new! Others still could be inspired by our growing knowledge of genetics and cell behavior. With each frontier we cross, there is likely to be another one waiting to be reached.
(The author is a leading Medical Oncologist who consults with Wockhardt Hospitals, Jaslok Hospital, Prince Aly Khan Hospital and Fortis Cancer Institute in Mumbai.)
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