Immunotherapy for Colorectal Cancer
Immunotherapy involves the use of drugs that enable a person’s immune system to attack cancer cells more effectively. These therapies target a specific feature of our immune system, the “checkpoint” proteins, which serve to prevent our immune system from attacking our body’s normal, healthy cells. These checkpoint proteins, however, can sometimes be used by tumour cells to help them “silence” the immune system and avoid being attacked. Immunotherapy drugs, also known as immune checkpoint inhibitors, act on the checkpoint proteins to restore the immune system’s response against tumour cells.
For the treatment of colorectal cancer, immunotherapy has been shown to be highly effective in a subset of patients who have specific genetic changes in their tumours, namely high microsatellite instability (MSI-H) or mutations in one of the mismatch repair (MMR) genes (also known as mismatch repair deficiency).
There Are Two Main Groups Of Immunotherapy Drugs:
PD-1 inhibitors
PD-1 inhibitors are drugs that target a protein called PD-1 which is found on T cells, a type of cell that is part of our immune system. PD-1 is involved in preventing T cells from attacking the body’s own cells. By blocking the activity of PD-1, these immunotherapy drugs increase the immune response against cancer cells.
Pembrolizumab (Keytruda ®), is given through intravenous infusion and can be used to treat patients with advanced or metastatic colorectal cancer that is microsatellite instability high (MSI-H) / mismatch repair (MMR) deficient as their initial (first line) treatment.
Nivolumab (Opdivo®) is given through intravenous infusion alone or in combination with ipilimumab (see below) for patients with metastatic colorectal cancer that does not respond to chemotherapy.
CTLA-4 inhibitors
Ipilimumab (Yervoy®) is an immunotherapy drug given intravenously that boosts the immune response by targeting a protein called CTLA-4. CTLA-4 is found on the surface of a type of immune cell, and it helps to keep the body’s immune responses in check. Ipilimumab is typically used in combination with nivolumab.
Nivolumab and ipilimumab are currently approved by Health Canada for the treatment of advanced colorectal cancer, though they are not covered by provincial health care plans. However, if immunotherapy could be right for you, talk to your medical team as some drugs may be accessible through compassionate access or expanded access programs.
Side Effects of Immunotherapy
In rare cases, immunotherapy may cause severe allergic and inflammation-related reactions.
It is important that you are able to contact a member of your healthcare team, day or night, and know when to seek medical attention if any of these potentially serious side effects occur. If you are ever in doubt, always report to the emergency department of your hospital without delay.
Side Effects of Immunotherapy
In rare cases, immunotherapy may cause severe allergic and inflammation-related reactions.
It is important that you are able to contact a member of your healthcare team, day or night, and know when to seek medical attention if any of these potentially serious side effects occur. If you are ever in doubt, always report to the emergency department of your hospital without delay.
Common Side Effects of Pembrolizumab (Keytruda ®) Include:
Common Side Effects of Nivolumab (Opdivo®) Include:
Common Side Effects of Ipilimumab (Yervoy®) Include:
Remember that not all patients will experience all of the side effects mentioned above. If you do experience any side effects, be sure to talk to your medical team to learn about options to help manage and prevent the worsening of side effects.
Some side effects can be cumulative and may become more severe with time or when given in combination with other drugs. Speak to your doctor to find out how to best manage your side effects.
