When people first hear about immunotherapy, a common question is whether it can treat their type of cancer. The answer is not always straightforward.
Immunotherapy is now part of treatment for several cancers, including some lung cancers, melanomas, kidney and bladder cancers, colorectal cancers and blood cancers. It also has a role in selected breast, liver, head and neck, stomach, cervical and prostate cancers.
What matters, though, is not just the name of the cancer. Its subtype, stage and biological features can all influence whether immunotherapy is worth considering. Your previous treatment and general health matter too.
What is immunotherapy?
The immune system is constantly protecting the body from infection and abnormal cells. Cancer is more difficult because it develops from the body's own cells. Some cancer cells also learn to hide from the immune system or interfere with the signals immune cells use to attack them. Immunotherapy tries to overcome some of these problems. Rather than describing one particular drug, immunotherapy is a broad name for treatments that help the immune system act against cancer. How they do this varies considerably.
What are the different types of cancer immunotherapy?
Immune checkpoint inhibitors
Think of immune checkpoints as controls that stop the immune system from becoming overactive. They are important because an uncontrolled immune response could damage healthy tissue.
Cancer cells can sometimes take advantage of these controls. Checkpoint inhibitors block certain signals and allow immune cells to remain active against the cancer.
You may hear your doctor mention PD-1, PD-L1 or CTLA-4. These are some of the checkpoint targets used in cancer treatment.
T-cell therapies
T cells are part of the immune system. Certain treatments use these cells more directly. With CAR T-cell therapy, T cells are collected from the patient and genetically modified in a laboratory so they can recognise a particular target on cancer cells. They are then returned to the patient. CAR T-cell treatment currently has an important role in certain blood cancers.
TIL therapy, short for tumour-infiltrating lymphocyte therapy, takes a different approach. Immune cells found within a tumour are collected and grown in large numbers before being given back to the patient. One TIL therapy, lifileucel, has FDA accelerated approval in the United States for certain adults with unresectable or metastatic melanoma after specified previous treatment.
Monoclonal antibodies
Monoclonal antibodies are made in a laboratory to recognise particular targets. Some help immune cells find cancer cells. Others bring immune cells and cancer cells closer together, making it easier for an immune response to occur.
There is an important distinction here. Not every monoclonal antibody is an immunotherapy. Some are classified as targeted treatments because of the way they work.
Cancer treatment vaccines
These are not the same as vaccines given to prevent an infection. Cancer treatment vaccines are given after cancer has developed. Their purpose is to encourage the immune system to recognise and respond to cancer. Sipuleucel-T, used for selected patients with metastatic castration-resistant prostate cancer, is one example.
Other immune-based treatments
Immunotherapy also includes approaches such as certain cytokines, immune-system modulators and oncolytic virus therapy. This variety is one reason the word “immunotherapy” can sometimes be confusing. Two patients may both be receiving immunotherapy while having very different treatments.
Which cancers can be treated with immunotherapy?
The list has grown considerably, but immunotherapy does not have the same role in every cancer.
Why does immunotherapy work for some people and not others?
Two tumours can share the same cancer name and still behave differently. This is where biomarker testing can become useful. A biomarker is a biological feature that may provide information about the cancer or help guide treatment.
For immunotherapy, doctors may look at PD-L1, MSI-H, dMMR or, in certain situations, TMB. Which tests matter depends on the cancer. CAR T-cell therapy uses specific targets in a different way. For example, some CAR T-cell treatments recognise CD19 in B-cell cancers, while others target BCMA in multiple myeloma.
No test tells the whole story. Your oncologist also looks at how far the cancer has progressed, treatments you have already received, other treatment choices, your general health, and the balance between possible benefit and harm. A favourable biomarker result can help with the decision, but it cannot promise a response.
Can immunotherapy be used with chemotherapy or other treatments?
Yes. Cancer treatment often involves more than one approach. For some cancers, immunotherapy is given with chemotherapy or targeted therapy. In other situations, it may be combined with radiotherapy or used before or after surgery. The order matters. So does the combination.
Your treatment team chooses an approach based on what has been shown to work for your particular cancer and treatment setting, rather than simply adding immunotherapy to another treatment.
What side effects can immunotherapy cause?
The side effects depend on the type of immunotherapy. With immune checkpoint inhibitors, activating the immune system can sometimes lead it to attack healthy tissue. This may cause inflammation in different parts of the body. Other forms of immunotherapy have their own side-effect patterns.
Some problems can become serious if they are not recognised early. Before treatment, your oncology team should tell you which symptoms need attention and how to contact them.
If you notice a new symptom or a change in how you feel during treatment, report it promptly, even if you are unsure whether immunotherapy is the cause.
Do not stop or change cancer treatment without discussing it with your oncology team.
How will my doctor know if immunotherapy is right for me?
There is no universal immunotherapy test. Instead, your oncologist puts several pieces of information together. These may include your pathology report, the exact type and stage of cancer, relevant biomarker results, treatments you have already received and your general health.
If immunotherapy is being discussed, you could ask:
Why are you considering immunotherapy for my cancer?
Do I need any biomarker tests first?
What are we hoping this treatment will achieve?
What side effects should I report?
What are my other treatment choices?
Will I receive immunotherapy on its own or with another treatment?
You do not need to understand every technical detail. What matters is understanding why the treatment is being recommended for you.
If you are considering immunotherapy or supportive care, speak with Dr Tarang Krishna and his team about how these options may fit your specific cancer, treatment needs and overall health.
