BIO 6.5 - Immunotherapy

Cancer

A disease where cells divide uncontrollably, forming an abnormal mass of cells called a malignant tumor. This can occur when several mutations occur to the same cell.

Mutation

A change in an organism’s genetic code

Mutagens

Agents that cause gene mutations

Examples of mutagens that can cause cancer

• Chemicals (carcinogens)

• High energy radiation (X-rays)

• UV light

• Some viruses

Common treatments for cancer

Chemotherapy - drugs that are cytotoxic to cancer cells, but also kill healthy body cells which divide rapidly

Radiation therapy - kills cells by damaging DNA, but also kills healthy cells

Surgery - removes cancerous tumours but some cancer cells could remain

Immunotherapy

A type of treatment that alters the immune response to combat disease

Non-specific immunotherapies

Inject cytokines to stimulate the immune system in general, causing a stronger response against cancer cells

Specific immunotherapies

Stimulate a specific adaptive immune response against the cancer through vaccines or monoclonal antibodies

Cancer vaccines

Contain peptides or whole proteins of cancer cells to stimulate an immune response against them.

OR - the patient’s own immune cells can be harvested and exposed to antigens, then injected back into the patient.

Monoclonal antibodies

Artificially produced antibodies that are used to treat cancer and autoimmune diseases

Process of making monoclonal antibodies (6)

1. An animal (mouse) is injected with an antigen from the cancer cell and produces specific plasma B cells

2. The plasma cells are harvested from the spleen of the animal

3. Plasma cells are fused with tumour or myeloma cells to form hybridoma cells that are immortal

4. The hybridoma cells are screened to determine which ones are producing useful antobodies

5. The selected hybridoma is allowed to divide and produce clones

6. Hybridomas are then used to synthesise large quantities of monoclonal antibodies to fight the cancer

Conjugated monoclonal antibodies

The antibodies are attached to a chemotherapy drug, toxin or radioactive particle and carries the treatment directly to the cancer cells

Bispecific monoclonal antibodies

Have 2 binding sites that bind to 2 different antigens (e.g. binds to a cancer cell and a cytotoxic T cell)

Uses of monoclonal antibodies in cancer treatment

• Directly attacks cancer cells

• Flags cancer cells for destruction

• Blocks cell growth

• Prevents blood vessel growth

• Blocks immune system inhibitors

Uses of monoclonal antibodies against autoimmune diseases

Antibodies slow down the immune responses that cause inflammation

• Binds to cytokines to stop their action and reduce inflammation

• Binds to B cells to stop the production of specific antibodies that attack self cells