What Is Targeted Therapy?
Cancer is a devastating illness. Mostly, because of how rapidly it spreads to other areas in the body. Because of this danger, researchers are developing treatments that have the ability to specifically target abnormal cells and then slow or stop those cells from growing and spreading. This method is known as targeted therapy. As scientists discover more about gene and protein changes, their focus is to develop new drugs that hone in and target those changes.
Targeted therapies offer an alternative treatment option to chemotherapy and radiation with less severe side effects. The reason why there are fewer side effects is that targeted treatment specifically targets abnormal cells, versus chemotherapy and radiation, which can’t distinguish between abnormal and healthy cells.
Mesothelioma and Targeted Therapy
Malignant mesothelioma is an aggressive, fatal disease that has seen rising cases over the past 60 years. A person with mesothelioma cancer is generally experiencing tumor growth in the lining (mesothelium) of the lungs, abdomen, or heart (pleura, peritoneum, or pericardium). Resarchers continue to test the use of various targeted therapies on mesothelioma patients in clinical trials.
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Targeted Therapy Types
There are two primary types of targeted therapies: monoclonal antibodies and molecule medications. Small molecule drugs can enter the cancer cells and disrupt a specific cancer growth pathway, and monoclonal antibodies fight cancer cells on the surface, or surrounding areas, and are too big to slip into cancer cells.
Sometimes, oncologists use monoclonal antibodies to launch chemotherapy and radiation treatments straight into tumors. This can occur through an IV in a vein, or as a shot. Monoclonal antibody medication treatments usually end with the stem “-mab.” Four monoclonal antibodies are used in mesothelioma:
- Bevacizumab – Humanized monoclonal antibody that targets the circulatory system (VEGF- vascular endothelial growth factor)
- Ipilimumab – Human antibody that targets CTLA-4, which activates the immune system
- Nivolumab- Nivolumab is a human IgG4monoclonal antibody that blocks PD-1 which activates the immune system
- Pembrolizumab – Humanized monoclonal IgG4 antibody that blocks PD-1 which activates the immune system
Signal Transduction Inhibitors
One of the most common targeted therapies, signal transduction inhibitors block signals that tell cancer cells to divide too much and too fast.
This form of treatment blocks the growth of blood vessels that cancer cells form in order to retrieve nutrients and oxygen. In the case of mesothelioma and some other cancers, the target is a substance called vascular endothelial growth factor (VEGF) and utilizes the drug bevacizumab. It’s usually administered in conjunction with chemotherapy medications pemetrexed and cisplatin.
This treatment utilizes the patient’s immune system to locate and destroy cancer cells. An oncologist can administer immunotherapies that boost the immune system to better attack cancer, or immunotherapies that highlight tumor cells so they’re quicker and easier for the immune system to find and attack.
This treatment is helpful in that it can penetrate cell membranes and interact with targets from the inside of a cell. Small molecule medicines are designed to interrupt the enzymatic activity of a specified protein and generally end with the stem “-ib.” Examples of small molecule medicine that are being tested in mesothelioma include:
- Olaparib and Rucaparib (PARP inhibitors )
- Defactinib (Tyrosine kinase inhibitor)
- Abemaciclib – Cyclin-dependent kinase inhibitor
- Pevonedistat – Proteasome inhibitor
Gene Expression Modulators
Another form of targeted therapy, gene expression modulators modify the proteins that control the abnormal instruction or expression of genes in cancer cells.
When cells die after growing old or becoming damaged, this is called apoptosis. Cancer cells tend to avoid this natural process, and apoptosis inducers cause abnormal cells to go through normal cell death.
Side-Effects of Targeted Treatment
As with most cancer treatments, targeted treatments come with side effects. A patient’s experience with these side-effects varies, as each individual’s case is unique. More common side effects include:
- Extreme Tiredness
- High Blood Pressure
- Loss of appetite
- Mouth Sores
Rarer, but possible side effects of targeted treatments can include:
- Blood clots
- Severe bleeding
- Holes in the colon (intestinal perforation)
Your doctor may have some medications available to help relieve side effects, and it’s recommended you call or stop by their office if you’re experiencing them.
Is Targeted Treatment Right for Me?
A doctor will need to test your tumors to find targets the treatments can focus on. They may use a biopsy to take these tests, which consists of sampling the tumor and then checking it in a lab. Two patients with the same type of mesothelioma may not have the same targets, and some medications may be ineffective if you do not have certain gene mutations. An oncologist may have to administer other mesothelioma medications or treatments before targeted therapy can be applied.
Chat with Your Doctor
You don’t have to go through this alone. Your oncologist will have resources available if you have any questions or issues during any of your mesothelioma treatment. If targeted therapy sounds like an option for you, definitely run that by your cancer-care team, so they can fully assess whether that’s the best option based on your health, mesothelioma stage, and other factors.