Immunotherapy for Cervical Cancer
Cervical cancer is not common in United States, but very common worldwide, with more than half a million women diagnosed each year worldwide. Nearly all cases are caused by human papillomavirus (HPV), which is a sexually transmitted infection. In most cases, an HPV infection is harmless and will resolve on its own after the body’s immune system fights it off. But, in some women, an HPV infection can persist and cause cellular changes in the cervix that can lead to the development of cervical cancer.
How is cervical cancer detected?
Cervical cancer grows very slowly and usually does not produce symptoms until it becomes invasive. However, it can often be detected early—before symptoms such as abnormal vaginal bleeding develop—through a routine Pap test. This relatively simple, noninvasive procedure involves collecting cells from the cervix. The sample is then examined by a pathologist under a microscope for signs of precancerous and cancerous changes. If found, these abnormalities can be promptly addressed.
Screening plays a vital role in preventing cervical cancer. A physician can recommend an appropriate screening plan, which may include periodic Pap and/or HPV testing.
How is cervical cancer treated?
When caught early, cervical cancer is very treatable. Some treatment options include surgery or radiation therapy with/without chemotherapy. The optimal approach can vary based on the extent of the cancer and the patient’s age and overall health.
While chemotherapy is a common treatment that can be very effective for addressing advanced or recurrent cervical cancer, it does have some limitations. For instance, some chemo drugs specifically target a certain cellular characteristic that is not present in every cancer cell. Other chemo drugs nonspecifically target the DNA of rapidly-growing cells, which are not always cancerous.
Recently, more options treatment such as immunotherapy was added to treatment tools. Immunotherapies do not have any such limitations. Instead, these treatments work by boosting the body’s own immune system, which can help it fight off cervical cancer.
Checkpoint blockade immunotherapy
One of the more innovative immunotherapy treatments for cervical cancer is checkpoint blockades. A checkpoint is a molecule on an immune cell that helps the immune system differentiate from healthy and foreign cells. When a checkpoint is working effectively, the immune system is able to attack foreign cells while leaving healthy cells alone. However, cancer cells can sometimes use these checkpoints to their advantage, circumventing their system to avoid being attacked by the immune system. This allows cancer cells to spread easily in the body.
Checkpoint blockade immunotherapy targets checkpoint molecules. In doing so, immune cells called T cells can recognize and attack tumors. Checkpoint inhibitors aren’t designed to work directly on tumors; instead, they allow the immune system to work more effectively. One type of checkpoint blockade immunotherapy for cervical cancer is called immunomodulators.
Pembrolizumab is a checkpoint inhibitor, a type of drug that blocks the PD-1 proteins in T cells. A type of white blood cell, T cells help keep the body healthy by fighting off invaders, such as viruses and cancer. The PD-1 proteins in T cells prevent the immune system from targeting healthy tissues by binding with the PD-L1 proteins found in many normal cells. However, PD-L1 proteins are also found in some cancerous cells, which means those cells are able to evade detection by passing as normal cells. When the PD-1 proteins in T cells are blocked by a checkpoint inhibitor, the “brakes” on the immune system are effectively released, allowing the T cells to better identify and destroy cancerous cells.
Checkpoint blockade immunotherapy is given intravenously with each treatment lasting 30 to 60 minutes. The number of treatments needed varies from patient to patient. While immunotherapy can be easier on the body than chemotherapy, side effects can occur, such as diarrhea, rash, kidney infections, pneumonitis and hormone issues.
Researchers continue to evaluate and develop new immunotherapies and other treatment options for cervical cancer. For instance, immunotherapies that target HPV-infected tumors are now being tested in clinical trials.
Can cervical cancer be prevented?
Several vaccines are approved by the FDA for the prevention of cervical cancer and other conditions caused by certain types of HPV. Since the introduction of the first HPV vaccine, the number of cervical cancer cases reported in the U.S. has dropped significantly. Researchers estimate that widespread vaccination could prevent more than two-thirds of all cervical cancers.
HPV vaccines are most effective when administered before HPV exposure. Because the peak time for acquiring an HPV infection is shortly after an individual becomes sexually active, many experts recommend vaccination prior to any sexual activity. A physician can suggest an appropriate cervical cancer prevention strategy, which may include an HPV vaccine.
In sum, comprehensive cervical cancer control involves three key steps: The first is prevention through vaccination against HPV. The second is prevention through routine screening and treatment of precancerous cervical lesions. The third is early diagnosis and appropriate treatment of cervical cancer.
Moffitt Cancer Center is leading the fight against cervical cancer
If you’d like more information on how cervical cancer can be prevented, diagnosed or treated, you can talk with an oncologist in the gynecological clinic at Moffitt Cancer Center. Our research team is continually exploring new ways to harness the body’s immune system to more effectively fight cervical cancer, and we are actively participating in clinical trials involving immunotherapies such as targeted antibodies, immunomodulators and vaccines.