Immunotherapy-Types of Immunotherapy for cancer




Immunotherapy-Types of Immunotherapy for cancer
Immunotherapy-Types of Immunotherapy for cancer

What is immunotherapy?

  • Immunotherapy is defined as one of the methods of treatment by inducing, enhancing, or suppressing an immune response.
  • It is one of the types of biological therapy in which the substances obtained from living organisms are used to treat cancer.
  • Generally, immunotherapies are classified into two groups:
    • Activation immunotherapies: includes immunotherapies employed for amplifying an immune response.
    • Suppression immunotherapies: includes immunotherapies that suppress or reduce an immune response.
  • Mostly, immunotherapies have been found to be promising to cure varieties of cancer.
  • Also, it often has fewer side effects in comparison to the existing drugs.

Relation between immunotherapy and immune system:

  • Immunotherapy helps to enhance immune cells by providing with additional components.
  • Immunotherapy instructs the immune system to identify and defend specific cancer cells.
  • Immunotherapy helps to eradicate cancer by boosting immune cells.

Types of Immunotherapy for cancer:

There are various types of immunotherapy. They are listed as follows:

  1. Monoclonal antibodies and tumor-agnostic treatments, such as checkpoint inhibitors
  2. Oncolytic virus therapy
  3.  CAR T-cell therapy
  4. Cancer vaccines
  5. Immune checkpoint inhibitors

1. Monoclonal antibodies (mAbs or MoAbs) and tumor-agnostic treatments:

  • When a threat is sensed by the immune system, it produces antibodies.
  • Antibodies are proteins that interact with antigens and initiate an immune response in the body.
  • Monoclonal antibodies are defined as antibodies that are prepared in laboratory in order to boost the natural antibodies or to defend the foreign threats itself.
  • Monoclonal antibodies help to fight cancer in several ways, for instance, monoclonal antibodies can be designed to fight with a specific cancer cell.
  • Thus, it is also termed as targeted therapy.
  • Basically, three types of mAbs are introduced, they are:
    • i. Naked monoclonal antibodies:
      • Most commonly used for treatment of cancer.
      • They are not attached to any other substance.
      • These antibodies instruct the immune system to defend cancer cells or block proteins within tumor.
    • ii. Conjugated monoclonal antibodies:
      • These are attached with either a radioactive particle or chemotherapy drug.
      • They are capable of attaching directly to the cancer cells.
      • It works by delivering the drug to the location of utmost requirement.
      • There are reduced or less chance of side effects and enhances the chemotherapy as well as radiation.
    • iii. Bispecific monoclonal antibodies (BsMAb):
      • These are antibodies designed in order to bind with two proteins at once.
      • Few can bind to both cancer cells and an immune system cell facilitating the immune response on cancer.

2. Oncolytic virus therapy:

  • In this type of treatment, viruses used are modified in the lab with a motive to infect and kill specific tumor cells.
  • Procedure of Oncolytic virus therapy:
    • First, the genetically modified virus is injected into the tumor.
    • Then the virus reaches the cancer cells and make copy of itself.
    • This leads to the disruption of cancer cells and ultimately their death.
    • As soon as the cells die, it stimulates the immune system to attack any cancer cells on the body having alike proteins as that of dead cells.
  • This modified oncolytic virus doesn’t affect healthy cells.
  • This therapy is considered superior to all other immunotherapies as it does not depend on any specific antigen expression patterns.
  • The features that makes it an ideal candidate for the treatment of diverse malignancies are as follows:
    • Oncolytic viruses enhance the recruitment of tumor-infiltrating lymphocytes (TILs)
    • Reprogramming of immunosuppressive tumor micro-environment (TME)
    • Boosts systemic anti-tumor immunity

 3. CAR T-cell therapy:

  • It stands for chimeric antigen receptor T-cell therapy (CAR T-cell therapy).
  • T cell, a type of leukocytes is one of the main constituents of the adaptive immune system.
  • In CAR T-cell therapy, the doctor reprograms T cells after taking out T cells from blood in order to find cancer cells more easily in contrast to it, T-cell therapy instruct the T-cells to search for tiny bits of specific antigens inside the cancer cells.
  • Procedure of CAR T-cell therapy:
    • At first T cells are isolated from patient’s blood.
    • Then, the receptors, which are specific proteins are added to it in the laboratory.
    • The receptors permit the T cells to identify cancer cells.
    • Then, the programmed T cells are then re-entered into the body.
    • Now, these cells find and destroy cancer cells.
  • Side effects such as low blood pressure, fever, confusion, and in rare cases, seizures are observed.

4. Cancer vaccines:

  • These are also termed as therapeutic vaccines.
  • The vaccines are employed to people already diagnosed with cancer with a motive to increase body’s natural defense in order to fight cancer.
  • The vaccines may either prevent the cancer from recurrence, destroy any cancer cells remnant even after the accomplishment of other treatments or stop a tumor from spreading.
  • Procedure of cancer vaccine therapy:
    • As we know, when the antibodies are produced in response to the antigens, the immune system develops memory cells, which will respond to these antigens in future.
    • Cancer vaccines enhance the immune system’s capacity to identify and destroy antigens.
    • Certain molecules termed as cancer specific antigens are present on the surface of the cancer cells, which are lacked by healthy cells.
    • These molecules act as antigens when given to a person, and trigger the immune system to identify and kill cancer cells having these molecules on the surface.
    • Few cancer vaccines also consist of adjuvants that may enhance the immune response.

5. Immune-checkpoint inhibitors:

  • It is the significant function of immune cells to be able to differentiate between the own normal cells and foreign cells.
  • Checkpoints are thus required, in order to monitor the foreign cells.
  • In general term, immune checkpoints are molecules on specific immune cells that needs to be either activated or inactivated for starting an immune response.
  • Drugs targeting these checkpoints are found to be promising for cancer treatment.
  • These drugs are hence termed as checkpoint inhibitors.
  • Two types of checkpoint inhibitors are described on the basis of proteins they target, they are:
  • i. Checkpoint inhibitors that target PD-1 or PD-L1:
    • T cells are immune cells and PD-1 is a checkpoint protein on it.
    • PD-1 protein prevents the T-cells from attacking other cells in the body, acting as a type of off switch.
    • It occurs when it is bound to PD-L1, which is a protein on some normal and cancer cells.
    • After the binding, it stops T-cells from attacking any cells favoring the cancer cells with high PD-L1 protecting it from immune attack.
    • Monoclonal antibodies targeting either PD-1 cells or PD-L1 cells can prevent the binding and enhance immune response against cancer cells.
      • Drugs targeting PD-1 (PD-1 inhibitors):
        • Pembrolizumab (Keytruda)
        • Nivolumab (Opdivo)
        • Cemiplimab (Libtayo)
      • Drugs targeting PD-L1 (PD-L1 inhibitors):
        • Atezolizumab (Tecentriq)
        • Avelumab (Bavencio)
        • Durvalumab (Imfinzi)
  • ii. Checkpoint inhibitors that target CTLA-4
    • Some T cells contain CTLA-4 protein that also acts as a off switch inorder to regulate immune system.
    • The CTLA-4 is inhibited by Ipilimumab (Yervoy) which is a monoclonal antibody that attaches to CTLA-4.
    • The body’s immune response is hence improved.
    • This drug is proved to treat melanoma of skin.
  • Side effects of checkpoint inhibitors include:
    • – Inflammation in the lungs
    • – Rashes along with itchiness
    • – Kidney infections
    • – Diarrhea

Immunotherapy-Types of Immunotherapy for cancer