Immunotherapy

Immunotherapy

• While chemotherapy or tumour-targeted drugs directly affect the growth and proliferation of tumour cells, immuno-oncological drugs harness the body’s natural anti-cancer immune response to attack and destroy the cancer.
• Manipulation of immune checkpoints is at the leading edge of immuno-oncology.

– Immune checkpoints are designed to turn off the immune response to prevent autoimmunity and damage to healthy cells, but cancer hijacks these mechanism by “deactivating” T cells once they have recognised the cancer, preventing attack and destruction of a cancer cell.

– Checkpoint inhibitors such as CTLA-4 inhibitors and PD-1 pathway inhibitors (two types already available in the clinic) or PD-L1 inhibitors (one type available in the clinic) prevent this deactivation and increase the body’s anti-tumour immune response.

How does modern immunotherapy differ from chemotherapy and tumour-targeted drugs?

• Chemotherapy involves the use of one or more drugs to destroy tumour cells, based on the fact that these cells typically divide rapidly; side effects are caused by damage to normal cells, especially those that also divide rapidly, such as cells in the bone marrow, hair follicle and gastrointestinal tract.
• Tumour-targeted drugs speci cally act against molecular targets in cancer cells identi ed by tissue and blood samples. These drugs are used to treat some types of cancer in selected patients based on molecular characteristics of their tumours. In general, it is expected that these drugs have less side effects on normal cells than chemotherapy, but side effects from tumour-targeted drugs could also be substantial and depend largely on what each drug targets.
• Because modern immunotherapy with checkpoint inhibitors blocks the body’s natural safeguards that prevent immune overactivation, it can also affect normal tissues and cause autoimmune side effects. These comprise a different spectrum of events compared with those associated with chemotherapy and tumour-targeted drugs, and require different management strategies.