The immune system uses special proteins called antibodies to fight off germs and other invaders. These antibodies stick to specific targets called antigens and help the body destroy cells containing these antigens. Scientists can create customized antibodies that target specific antigens, like those found on cancer cells. These are called monoclonal antibodies (mAbs or Moabs), and they’re made in labs. Monoclonal antibodies are used to treat various diseases, including some types of cancer. But it’s not always easy to find the right targets on cancer cells, so these treatments work better for some cancers than others.
Some monoclonal antibodies act like targeted therapy, blocking specific functions in cancer cells. Others help the immune system find and attack cancer cells more effectively, acting more like immunotherapy.
How Monoclonal Antibodies Treat Cancer?
Monoclonal antibodies are used to treat various types of cancer. Administered through an infusion, they can be used alone or alongside other cancer treatments. Each monoclonal antibody targets specific antigens, working in one or more ways.
Some monoclonal antibodies bind directly to cancer cells to kill them, targeting specific receptors. These are known as targeted therapies. For example, trastuzumab (Herceptin) treats HER2-positive breast and stomach cancers by attaching to HER2 receptors on cancer cells, preventing their multiplication and slowing cancer progression.
Other monoclonal antibodies enhance the immune system’s response to cancer cells, functioning as immunotherapy. Nivolumab, which targets the PD-1 receptor, is used to treat various cancers, including lung, kidney, melanoma, lymphoma, and some head and neck cancers.
Immunotherapy drugs like nivolumab can sometimes cause severe side effects, such as inflammation in the colon or lungs, as the immune system may attack normal tissue. To manage this inflammation, patients may stop immunotherapy and receive steroids. If steroids are ineffective, a different monoclonal antibody may be administered to reduce the inflammation.
What mAbs Are Made Of?
Monoclonal antibodies (mAbs) are man-made proteins designed to function like human antibodies in the immune system. They can be produced in four different ways, each named according to their composition:
Murine: These antibodies are made entirely from mouse proteins. Treatments using murine antibodies have names that end in “-omab”.
Chimeric: These antibodies are part mouse and part human. By combining elements from both species, they create a hybrid protein. Treatments with chimeric antibodies end in “-ximab”.
Humanized: These antibodies are mostly human but include small segments of mouse proteins. This combination aims to reduce immune reactions while maintaining the antibody’s effectiveness. Treatments using humanized antibodies end in “-zumab”.
Human: These antibodies are composed entirely of human proteins. They are designed to be fully compatible with the human immune system, minimizing the risk of rejection or adverse reactions. Treatments with human antibodies end in “-umab”.
Types of Monoclonal Antibodies in Cancer Treatment
Monoclonal antibodies (mAbs) play a major role in cancer treatment, offering tailored approaches to target cancer cells and strengthen immune responses. Let’s understand the different types of mAbs utilized in cancer therapy:
Naked Monoclonal Antibodies
These antibodies operate independently without any drug or radioactive material attached. They primarily target antigens on cancer cells, acting as markers for the immune system to destroy them. For instance, rituximab (Rituxan) binds to CD antigens on B lymphocytes, enhancing immune responses against lymphoma cells. Other naked mAbs, like trastuzumab (Herceptin), block proteins on cancer cells to inhibit their growth, such as the HER2 protein in breast and stomach cancers.
Conjugated Monoclonal Antibodies
Conjugated mAbs are linked to chemotherapy drugs or radioactive particles, acting as carriers to deliver these substances directly to cancer cells. Antibody-drug conjugates (ADCs) like brentuximab vedotin (Adcetris) and ado-trastuzumab emtansine (Kadcyla) target specific antigens on cancer cells while delivering potent chemotherapy drugs. Radiolabeled antibodies, on the other hand, utilize small radioactive particles to target and irradiate cancer cells directly, a process known as radioimmunotherapy (RIT).
Bispecific Monoclonal Antibodies
Bispecific mAbs consist of parts from two different antibodies, allowing them to attach to two distinct proteins simultaneously. Bispecific T-cell engagers (BiTEs) are a notable example, where one part binds to a protein on cancer cells while the other attaches to T cells, facilitating a more robust immune response against cancer cells. BiTEs are increasingly vital in the treatment of certain cancers, enhancing the immune system’s ability to target and destroy cancerous cells.
Understanding the distinct mechanisms and applications of these monoclonal antibodies is crucial for optimizing cancer therapy and improving patient outcomes.
Which Cancers Can Be Treated With Monoclonal Antibodies?
Monoclonal antibodies (mAbs) are used to treat a variety of cancers. Some of the cancers commonly treated with mAbs include:
- Breast Cancer: Monoclonal antibodies may target proteins like HER2 found on breast cancer cells, helping to slow or stop their growth.
- Colorectal Cancer: In colorectal cancer, monoclonal antibodies can interfere with signals that promote tumor growth, aiding in controlling the disease.
- Lymphomas: Monoclonal antibodies can recognize and attach to specific proteins on lymphoma cells, assisting in directing the immune system to destroy them.
- Leukemias: Monoclonal antibodies may be utilized to target leukemia cells, enhancing immune-mediated killing and impeding disease progression.
- Lung Cancer: Certain monoclonal antibodies target proteins on lung cancer cells, hindering their growth and spread.
- Melanoma: Monoclonal antibodies can be designed to recognize proteins expressed on melanoma cells, aiding in immune-mediated clearance of cancerous cells.
- Stomach Cancer: Monoclonal antibodies may bind to specific targets on stomach cancer cells, impeding their proliferation and facilitating their elimination by the immune system.
- Head and Neck Cancers: In head and neck cancers, monoclonal antibodies can target proteins like EGFR, inhibiting cancer cell growth and enhancing treatment effectiveness.
Also Read: What is the Success Rate of Immunotherapy?
Side Effects of Monoclonal Antibodies
Monoclonal antibodies can cause side effects that vary from person to person. The specific side effects you might experience depend on several factors, including your overall health, the type and stage of your cancer, the type of monoclonal antibody you receive, and the dosage.
Healthcare providers cannot predict exactly when or if side effects will occur or how severe they might be, so it’s crucial to be aware of potential signs and know what to do if you experience any problems.
Common side effects, similar to those from other immunotherapies, include skin reactions at the injection site and flu-like symptoms.
Injection site reactions can include:
- Pain
- Swelling
- Soreness
- Redness
- Itchiness
- Rash
Flu-like symptoms can include:
- Chills
- Fatigue
- Fever
- Muscle aches and pains
- Nausea
- Vomiting
- Diarrhea
Monoclonal antibodies can also cause other side effects, such as:
- Mouth and skin sores, which can lead to serious infections
- High blood pressure
- Congestive heart failure
- Heart attacks
- Inflammatory lung disease
In some cases, monoclonal antibodies can cause allergic reactions during treatment, which can range from mild to severe, and, in rare instances, be life-threatening.
Other potential side effects include:
Capillary Leak Syndrome: This condition causes fluid and proteins to leak from tiny blood vessels into surrounding tissues, leading to dangerously low blood pressure, multiple organ failure, and shock.
Cytokine Release Syndrome: Although often mild, this syndrome can occur with monoclonal antibodies. It involves a sudden increase in cytokines, which are immune system substances. Symptoms may include:
- Fever
- Nausea
- Headache
- Rash
- Rapid heartbeat
- Low blood pressure
- Trouble breathing
It’s essential to communicate with your healthcare team about any side effects you experience to manage them effectively.
Conclusion
Monoclonal antibodies (mAbs) are a big step forward in cancer treatment. They target cancer cells precisely, stopping their growth or flagging them for the immune system to attack. mAbs also boost the body’s defenses against cancer, playing a key role in immunotherapy. By blocking immune checkpoints or delivering drugs directly to cancer cells, mAbs enhance immune responses. This combination of mAbs and immunotherapy is changing cancer care, giving patients hope for better outcomes.
Also Read: Immunotherapy Drugs for Cancer
