How is immunotherapy used to treat cancer?
Immunotherapy is a type of cancer treatment in which the body’s immune system is used to treat the cancer. It is also known as biological therapy. In this form of treatment, the immune system is stimulated to be an effective force in fighting cancer.
In immunotherapy, doctors also use lab—made substances that function like the components of your immune system to improve its efficiency in finding and attacking cancer cells.
What are the types of immunotherapy?
There are different types of immunotherapy. Few of these are available at clinics while many are under clinical trial or research.
Biological response modifiers:
• This form of therapy has an indirect impact on the tumour by triggering your immune system to effectively work against them. Examples are cytokines such as interleukins and interferons.
• For this type of treatment, larger doses are injected or infused to try and stimulate the immune system cells so that they can act more effectively.
Tumour vaccines: (Under Clinical Trial)
• A concept in development with research still going on its benefits and effectiveness
• Once developed and ready, these vaccines are administered just like many other vaccines
• They will be given after initial cancer treatment has been done, and will help to prevent the cancer from coming back again
• It may also help the body in rejecting any tumour lumps
CAR-T Cells – Currently not commercially available in India
Chimeric antigen receptors (CARs, also known as chimeric immunoreceptors, chimeric T cell receptors or artificial T cell receptors)
CAR-T cell therapy uses T cells (immune system cells) engineered with CARs for cancer therapy. The premise of CAR-T immunotherapy is to modify T cells to recognize cancer cells in order to more effectively target and destroy them. Scientists collect these T cells from people, genetically alter them, then infuse the resulting CAR-T cells into patients to attack their tumors. CAR-T cells can be either derived from T cells in a patient’s own blood (autologous) or derived from the T cells of another healthy donor (allogeneic). Once isolated from a person, these T cells are genetically engineered to express a specific CAR, which programs them to target an antigen that is present on the surface of tumours. For safety, CAR-T cells are engineered to be specific to tumours and do not harm normal cells.
Dendritic Cell therapy- commercially not available in India.
Dendritic cell therapy provokes anti-tumor responses by causing dendritic cells to present tumour antigens to lymphocytes (immune system cells) , which activates them, priming them to kill other cells that present the antigen (tumor cell specific). Dendritic cells are antigen presenting cells (APCs) in the mammalian immune system. In cancer treatment they aid cancer antigen targeting. The only approved cellular cancer therapy based on dendritic cells is sipuleucel-T in prostate cancer
Immunotherapy Drugs available commercially.
Cancer cells affect immune system cells of patient which results in immune cells protecting cancer cells rather than killing these. Immunotherapy drugs are also called ‘checkpoint inhibitors’ prevent cancer cells from stopping patient’s immune system from doing its work, which in turn track and destroy the cancer cells. These are currently approved in many cancers and showing promising results even in advanced cancers.
The most common types of immunotherapy drugs are:
• Ipilimumab (Yervoy)
• Nivolumab (Opdivo)
• Pembrolizumab (Keytruda)
• Atezolizumab (Tecentriq)
How is immunotherapy treatment given?
Currently these are available as parenteral (intravenous) preparations. These are delivered at regular intervals (every 2 or 3 or 4 weeks) alone or with other targeted agents with close monitoring of side effects. Assessment of response to these modalities is done as per protocol.
What are the side effects of immunotherapy?
It is possible that some patients face different side effects from immunotherapy, such as:
• Feeling excessive fatigue
• Symptoms that mimic the flu
• Skin reaction, such as redness, swelling, itching or pain in the area where the needle was administered
• Pneumonitis (inflammation of the lungs) causing shortness of breath, chest pain
• Hepatitis (inflammation of the liver) causing dark urine, yellowing of skin or eyes, pain in the right side of the stomach, bleeding or bruising easily
• Myocarditis (inflammation of the heart muscle) causing shortness of breath, irregular or fast heartbeat, pain in the chest
• Uveitis (inflammation of the eyes) causing changes in vision
• Hormonal disorders (endocrine disorders) causing sweating, fast heartbeat, mood swings, sensitivity to cold, excessive fatigue, headache, hair loss
• Colitis (inflammation of the bowel) causing more frequent passing of stool than usual, pains in the stomach, mucus or blood in the stool, diarrhoea
• Arthritis causing pain in the joints or muscles
In most cases, these side effects will be mild and your doctor will be able to help you manage them best. Some patients may experience severe effects, and should immediately inform the doctor of the same.