While this could be very good news, I realized that the headline could be unintentionally misleading. This experimental new skin cancer vaccine will only treat patients who are already sick. Why is it called a vaccine if it doesn’t prevent cancer?
I biochemist When molecular biologist I study the role of microorganisms in health and disease. He also teaches cancer genetics to medical students and is interested in how the public understands the science. Prophylactic and therapeutic vaccines are administered for a variety of health care purposes, but both train the immune system to recognize and fight off specific disease-causing pathogens.
How do preventive vaccines work?
Most vaccines are given to healthy people before they get sick to prevent diseases caused by viruses and bacteria. These include vaccines to prevent polio, measles, COVID-19, and many other diseases.Researchers have also developed a vaccine prevent some types of cancer It is caused by viruses such as human papillomavirus and Epstein-Barr virus.
your immune system It recognizes objects such as specific microorganisms and allergens that do not belong to the human body and initiates a series of cellular events that attack and destroy them. Therefore, viruses and bacteria that enter the body are recognized as foreign substances and trigger an immune response to fight off the microbial invaders. cellular memory This triggers an even faster immune response the next time the same organism invades.
The problem is that the first infection can cause serious illness before the immune system can react to it. Suffering the potentially harmful consequences of the initial infection.
This is where preventive vaccines come in. By introducing a harmless version or part of a microbe into the immune system, the body can learn to mount an effective response against it without causing disease.
for example, Gardasil-9 vaccine It protects against human papillomavirus (HPV), which causes cervical cancer. It contains protein components found in viruses that do not cause disease but induce an immune response that protects against future HPV infections, thereby preventing cervical cancer.
How does the Moderna cancer vaccine work?
Unlike cervical cancer, cutaneous melanoma is not caused by a viral infection. latest evidenceAlso, Moderna’s experimental vaccine does not prevent cancer like Gardasil-9.
Moderna’s vaccine trains the immune system to fight off invaders, much like the preventive vaccines most people are familiar with. In this case, however, the invader is a tumor, a rogue version of normal cells harboring abnormal proteins that the immune system can recognize as foreign and attack.
What are these unusual proteins and where do they come from?
All cells are composed of proteins and other biomolecules such as carbohydrates, lipids and nucleic acids. Cancer is caused by mutations in regions of the genetic material or DNA that code for instructions about what proteins to make.A mutated gene results in what is called an abnormal protein neoantigen The body perceives it as a foreign object. This may trigger an immune response that fights off nascent tumors. However, sometimes the immune response fails to suppress the cancer cells either because the immune system cannot mount a strong enough response or because the cancer cells have found ways to evade the immune system’s defenses.
Moderna’s experimental melanoma vaccine contains genetic information that codes for some of the neoantigens in the tumor. This genetic information mRNAwhich is the same format used in Moderna, and Pfizer Biotech COVID19 vaccine. Importantly, the vaccine does not cause cancer because it only encodes a small, nonfunctional portion of the protein. When the genetic information is translated into these protein pieces in the body, the immune system launches an attack on the tumor. Ideally, this immune response causes the tumor to shrink and disappear.
Specifically, the Moderna melanoma vaccine is tailored to each patient. Because each tumor is unique, so should the vaccine. To customize a vaccine, researchers first biopsy a patient’s tumor to determine which neoantigens are present. Vaccine manufacturers then design specific mRNA molecules that encode these neoantigens. When this custom mRNA vaccine is administered, the body converts the genetic material into proteins specific to the patient’s tumor, resulting in an immune response against the tumor.
Combined vaccination and immunotherapy
the vaccine is immunotherapyIt uses the immune system to treat disease. However, other immunotherapeutic anticancer agents are not vaccines. Because it also stimulates the immune system but does not target specific neoantigens.
In fact, the Moderna vaccine is co-administered with immunotherapeutic drugs pembrolizumab, marketed as Keytruda. Why do we need two drugs?
certain immune cells called T cells Have Molecular accelerator and brake components It serves as a checkpoint to ensure that it is only activated in the presence of foreign invaders such as tumors. However, sometimes tumor cells find ways to keep the T cell brake on and suppress the immune response. In such cases, the Moderna vaccine correctly identifies the tumor, but the T cells cannot respond to it.
However, pembrolizumab can bind directly to the brake component of T cells, inactivating the brake system and allowing immune cells to attack tumors.
Not a cancer vaccine
So why can’t the Moderna vaccine be given to healthy people to prevent melanoma before it occurs?
Cancer varies greatly from person to person. Each melanoma has a different neoantigen profile that cannot be predicted in advance. Therefore, we cannot develop a vaccine before we get sick.
An experimental mRNA melanoma vaccine, currently in early-stage clinical trials, is an example of a new frontier in personalized medicine. By understanding the molecular basis of diseases, researchers can explore how their underlying causes vary from person to person, providing personalized treatment options for those diseases.
This article is reprinted from conversation, is a non-profit news site dedicated to sharing ideas from academic experts. If you find it interesting, Subscribe to our weekly newsletter.
It was written by: Mark R. O’Brien, University of Buffalo.
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Mark R. O’Brian is funded by the National Institutes of Health.
