Immunotherapy in Cancer Treatment

Dr P G Balagopal MS,MCh
Superintendent , Cochin Cancer Research Centre

History
William B Coley is known as the father of immunotherapy. He observed that a number of cancer patients went into spontaneous remission after developing erysipelas. Erysipelas is a bacterial infection affecting skin.

He started injecting mixtures of live and inactivated Streptococcus pyrogenes and Serratia marcescens bacteria into patients tumors in 1891.He could achieve durable complete remission in different kinds of malignancies like sarcoma, testicular carcinoma, and lymphoma. But it failed to get acceptance in medical community because of lack of a known mechanism of action for Coley’s toxins and risks of injecting pathogenic bacteria into cancer patients .

The immunotherapy came into lime light in 1950’s when Thomas and Burnet first proposed the theory of immunosurveillance. They suggested that lymphocytes acted as sentinels to identify and eliminate somatic cells transformed by spontaneous mutations. In 1970 it was observed that the large doses of Interleukin -2 is effective in treating metastatic cancers by increasing the T cell production. But the first drug for immunotherapy was approved by FDA in 1997 only.

Immunotherapy is a type of treatment that uses body’s own immune system to help to fight cancer. In immunotherapy the immune system is artificially stimulated i.e. improving the natural ability of ones own immune system to treat cancer. This can be done in two ways
1)Stimulating ones own immune system through immunotherapy

2) Giving man made immune system proteins to fight cancer

Types of immunotherapy,
Many drugs with different mechanism of actions are used in Immunotherapy, they are

1)Check point Inhibitors –They block proteins that stop the immune system from attacking cancer cells

2)Monoclonal Anti Bodies- These are antibodies produced by identical immune cells that are all clones of unique parent cell

3) Cancer Vaccines –Is the kind of vaccine that either treats existing cancer or it prevent the development of cancer. Some / many of the vaccines are autologous being prepared from the samples taken from the patient and specific to that patient.

4)Cytokines- Is a protein that is important in cell signaling. It is believed that cytokines are involved in autocrine signaling, paracrine signaling and endocrine signaling as immunomodulating agents

5)Adoptive Cell transfer is the transfer of cells originated from the immune system of the patient or another individual with the goal of improving the function and characteristics of immune system

Mechanism of action of Immunotherapy
The immunotherapy works by stopping or slowing the growth of cancer cells or stopping cancer cells from spreading to other parts of the body.The role of immunotherapy is to improve the specificity and memory of the adaptive immune response to achieve long term tumour suppression and possible cure, by administering cytokines and vaccines to increase the frequency of tumour specific T cells and adoptive transfer of tumour of specific effector cells or by using check point inhibitors to overcome the cancer cell induced tumour suppressive mechanisms

Routes of Administration
The immunotherapy drugs can be given in different ways
1) Oral – where the immunotherapy comes in the form of capsules or tablets
2)Topical- Here the immunotherapy comes in the form of cream that the patient can rub on to the skin
3)Intravenous- The medicine is given directly into the vein
4) Intravesical- where the drug goes directly into the bladder

Types of Cancer treated by Immunotherapy
Immunotherapy is not used to treat all forms of cancers, it is mainly used to treat following cancers
1) Lung Cancer
2) Melanoma
3) Skin Cancers
4) Bladder Cancer
5)Lymphoma

Side Effects
The immunotherapy is not without side effects. The side effects are common, but may not occur in all patients or with all types of therapies.The common side effects include
1)Fever
2)Fatigue
3) Nausea
4) Vomiting
5) Skin Rashes or blisters
6) Itching
7) Shortness of breath

Difference between chemotherapy and immunotherapy
The difference between chemotherapy and immunotherapy is in chemotherapy drugs act directly on cancer cells but in immune therapy the drugs act on the immune system of the patient.

Expense
The immunotherapy is very expensive, the treatment to be continued for three to six months depending on the condition of the patient, one therapy ( cycle) of immunotherapy is required for 21 days and the cost of one therapy is in the range of 1- 1.3 lakhs or more .

Conclusion
The immunotherapy is not very poular in India because it is expensive ,not available at all cancer centres and the number of qualified medical oncologists are few in number.