Immunotherapy for Cancer: An Overview
What is immunotherapy?
Immunotherapy is a type of cancer treatment that uses the body’s immune system to fight cancer. It works by stimulating the immune system to help it do its job more effectively against cancer cells. The immune system consists of a complex process that the body uses to fight cancer, involving cells, organs, and proteins. Cancer cells can sometimes evade the immune system’s natural defenses, allowing them to continue growing. Immunotherapy helps the immune system better recognize and attack cancer cells. It can be used alone or in combination with other treatments like chemotherapy.
How does immunotherapy work?
There are several key mechanisms by which different types of immunotherapy stimulate the immune system to target and destroy cancer cells:
- Blocking Immune Checkpoints: Immune checkpoint inhibitors block proteins like PD-1 that act as “brakes” on the immune system. By blocking these checkpoints, the drugs allow T cells to respond more strongly against cancer cells. Anti-PD-1 antibodies work not only in the tumor itself but also in the lymph nodes, where they recruit new lymphocytes to fight the tumor.
- Activating T Cells: Some therapies work by directly activating T cells to attack cancer. T-cell transfer therapy involves boosting the natural ability of a patient’s T cells to fight their specific cancer. Chimeric antigen receptor (CAR) T-cell therapy engineers a patient’s T cells in the lab to better recognize and kill cancer cells.
- Stimulating the Immune System: Cytokines and immunomodulators are drugs that stimulate the immune system in various ways to enhance its cancer-fighting abilities. Cancer vaccines work by exposing the immune system to tumor antigens to generate a specific immune response against cancer.
- Targeting Tumor Antigens: Monoclonal antibodies are designed to attach to specific targets on cancer cells, helping the immune system identify and attack those cells. Antibody-drug conjugates and bispecific T-cell engagers also use antibodies to deliver cancer-killing agents or connect T cells to tumor cells.
Watch this informative video about how the immune system fights against cancer from the National Cancer Institute.
By harnessing different mechanisms to activate the immune system, immunotherapies have shown promise in treating a wide range of cancers. However, they don’t work for everyone, and researchers are working to improve their effectiveness, predict responses, and reduce side effects.
Types of immunotherapy
The types of immunotherapy include various approaches that leverage the body’s immune system to combat cancer. Here are some key types based on the provided sources:
- Checkpoint Inhibitors: These drugs block proteins on T-cells that act as “brakes” on the immune system, allowing T-cells to recognize and destroy cancer cells. Examples include pembrolizumab (Keytruda) and ipilimumab (Yervoy).
- Monoclonal Antibodies (MABs): These antibodies recognize and attach to specific proteins on cancer cells, helping the immune system target and attack cancer cells. MABs can trigger the immune system or assist it in attacking cancer.
- CAR T-cell Therapy: This therapy involves modifying a patient’s T cells in the lab to better recognize and kill cancer cells. CAR T-cell therapy is used for certain types of leukemia and lymphoma and is being researched for other cancers like breast and brain cancer.
This image is taken from cancer.gov
- Cytokines: These proteins naturally found in the body play a role in boosting the immune system. Man-made versions of cytokines like interferon and interleukin are used to treat some types of cancer.
- Vaccines for Cancer Treatment: Unlike preventive vaccines, cancer treatment vaccines are designed for individuals already diagnosed with cancer. These vaccines help the immune system recognize and mount an attack against specific cancer cells by targeting proteins in the cancer cells.
These types of immunotherapy work in different ways to enhance the immune system’s ability to identify and eliminate cancer cells, offering promising treatment options for various types of cancer.
Signs immunotherapy is working
The signs that immunotherapy is working include:
- Tumor Response: Therapy is considered effective when a tumor shrinks in size or stops growing. It’s important to note that immunotherapy drugs may take longer to shrink tumors compared to traditional treatments like chemotherapy. In some cases, tumors may appear to enlarge on scans before getting smaller, known as pseudoprogression, which indicates that the treatment is working as immune cells penetrate and attack the tumor.
- Side Effects: Side effects such as inflammation can confirm that therapy is impacting the immune system. In certain cancers, specific side effects like vitiligo (white patches of blotchy skin) can indicate a higher likelihood of treatment success. Notably, melanoma patients who develop vitiligo are more likely to respond positively to immunotherapy.
- Immune-Related Side Effects: Immune checkpoint inhibitors, a common form of immunotherapy, can lead to immune-related adverse events (irAEs) like diarrhea, skin reactions, lung inflammation, and thyroid inflammation. Studies have shown that patients experiencing these side effects tend to have better survival outcomes, indicating that the immune system is actively responding to the treatment.
- Tumor Monitoring: Regular scans of the tumor are essential to track its response to immunotherapy. In some cases, the tumor may initially appear larger on scans due to pseudoprogression, but this does not necessarily mean the treatment is ineffective. Doctors may recommend waiting for additional treatment cycles to confirm the response.
These signs collectively help healthcare providers assess the effectiveness of immunotherapy and make informed decisions about the continuation of treatment or the need to explore alternative therapies.
Immunotherapy side effects
The side effects of immunotherapy can vary depending on the type of treatment received and the individual’s response to the therapy. Common side effects of therapy include:
- Fatigue
- Itchy rash
- Diarrhea
- Nausea and vomiting
- Decreased thyroid hormone levels
- Allergic reactions affecting the skin
- Increased enzyme levels in the liver
- Inflammation in the lungs (pneumonitis)
- Hormonal imbalances affecting the thyroid
- Nervous system conditions
- Cardiovascular issues like irregular heartbeat
- Joint inflammation (arthritis)
- Side effects specific to different types of immunotherapy such as immune checkpoint inhibitors, adoptive cell therapy, CAR T-cell therapy, monoclonal antibodies, and vaccines.
FAQs
Can immunotherapy cure stage 4 cancer?
Immunotherapy offers hope by prolonging survival and enhancing the quality of life for stage 4 cancer patients, but it does not guarantee a cure. Stage 4 cancer, also known as metastatic cancer, is generally considered incurable, but treatments aim to manage symptoms and extend life. Therapy has shown great promise in treating stage 4 cancer by helping the body fight cancer cells more effectively, offering a potential game-changer in cancer treatment.
How is immunotherapy administered?
Depending on the type of treatment and the patient’s condition, immunotherapy can be administered through:
- IV immunotherapy: Administered directly into the vein as an infusion.
- Intravesical immunotherapy: Administered as a liquid medication, typically used for early-stage bladder cancer.
- Oral immunotherapy: Administered as a powder or drops, often taken with food or under the tongue.
- Subcutaneous immunotherapy: Injected under the skin.
- Topical immunotherapy: Applied to the skin as a cream.
The duration of an immunotherapy session also varies depending on the type of treatment and the severity of the condition: it typically lasts between 30 and 90 minutes, with doses given every two to three weeks for up to two years.
What are the benefits of immunotherapy treatment?
Immunotherapy treatment offers benefits such as targeting individual mutations in cancer cells, effectively combating resistant cancer, and stimulating the immune system to recognize and destroy cancer cells. It can lead to long-term remission by targeting cancer stem cells and often has fewer side effects compared to traditional treatments like chemotherapy.
What is the success rate of immunotherapy?
The success rate of immunotherapy varies depending on the type of cancer but generally falls between 15-50%. Immunotherapy works better for some cancers than others, with an overall response rate of about 15-20%. While therapy can be highly effective for some patients, it does not work for everyone.
What are the risks of cancer immunotherapy?
The risks of cancer immunotherapy include ineffective treatment, side effects like flu-like symptoms and autoimmune-like effects, and life-threatening conditions such as organ damage and nervous system disorders. Younger age, melanoma, and kidney cancer are predictive of severe therapy toxicities. Patients must discuss the pros and cons with their healthcare provider.
What are cancer vaccines?
Cancer vaccines are a type of immunotherapy that train the immune system to recognize and attack cancer cells. They work by exposing the immune system to specific antigens found on cancer cells, enabling it to identify and destroy those cells. Cancer vaccines can be used to treat existing cancer or prevent certain virus-related cancers like cervical and liver cancer. There are two main types of cancer vaccines:
- Preventive Cancer Vaccines: These vaccines protect against certain viral infections that can lead to cancer. Examples include the HPV vaccine, which prevents cervical cancer and other cancers caused by the human papillomavirus, and the hepatitis B vaccine, which reduces the risk of liver cancer.
- Therapeutic Cancer Vaccines: These vaccines are used to treat cancer after it occurs. They work by training the body’s immune system to recognize and attack cancer cells. Therapeutic cancer vaccines can help stop tumor growth, destroy remaining cancer cells after treatment, and prevent cancer from recurring.
How long does immunotherapy stay in your system?
Immunotherapy can continue working long after treatment stops, as it strengthens the immune system’s ability to fight cancer. While some immunotherapies are given daily, weekly, or monthly, many patients receive them in cycles with rest periods in between. The optimal duration of immunotherapy is still being studied, but some patients achieve durable responses with shorter courses, potentially limiting the toxicity of prolonged treatment.