World Cancer Day: Can a vaccine eradicate the other pandemic of the 21st century?

Not only did he die of COVID-19 in 2020. In the same year, about 10 million people died from cancer, more than five times more than from the new coronavirus, according to data published by the World Health Organization (WHO) on the occasion of the World Cancer Day.

To these deaths were added the collateral victims of the emergency situation that they saw how they received a late diagnosis or suffered delays in the beginning of their treatments due to the saturation of the health systems of their countries.

Between March and June 2020, as a result of the confinement, they were detected in Spain 21% fewer new cases, according to data from the Spanish Association for Scientific Communication (AECC).

However, cancer did not cease, with 19.3 million diagnoses in the last year, worldwide. Currently one in five people will get cancer in their lifetime. The WHO warns that by 2040 the number will increase by up to 50%.

With vaccines more than ever in full swing, could they end not only the coronavirus pandemic?

Vaccines are given to achieve long-lasting immunity by inoculating attenuated or inactivated parts of a disease to teach the immune system to defend itself.

The only disease that has been completely eradicated thanks to vaccination has been smallpox, a virus with high mortality rates – 30% of those infected died – and which was characterized by the appearance of pustules, which could trigger a fatal inflammatory response.

The last person diagnosed with this disease dated 1977, three years later the WHO certified its eradication.

The end was written by a vaccine that consisted of injecting the virus vaccinia, first isolated in horses and similar to smallpox, in healthy people to produce mild illness and educate the immune system before the deadly virus is caught.

Although this has been the most successful case, the list of diseases that vaccination has managed to reduce to a minimum is extensive: diphtheria, poliomyelitis, measles, tetanus …

The vaccines that already exist against cancer

Currently there are already vaccines that can prevent some types of cancer, but the challenge is that most cases do not originate from an infectious agent like a virus or a bacterium, explains to Euronews the researcher Rubén Pío, director of the Solid Tumors Program at the University of Navarra.

“We must distinguish between preventive and therapeutic vaccines”, Pío points out, “the COVID vaccine, for example, is preventive because you receive it when you are healthy to activate defense mechanisms against the infectious agent.”

This can also train the immune system to defend itself against viruses that can cause cancer, but only 25% of cases are caused by an infection, according to WHO data.

Therefore, the field of preventive vaccination against cancer is not very extensive, but there are examples.

The most widespread is the human papillomavirus (HPV) vaccine, indicates Pío, which is an infection that can cause cancers of the cervix or throat, among others. Another vaccine that can prevent some cases of cancer, specifically liver cancer, is that of hepatitis B.

But the possibilities of vaccination against cancer are not only limited to prevention. “You can also use therapeutic vaccines, which teach your immune system to recognize the tumor when it is already present,” explains the researcher.

Pío cites, for example, the Heberprovac vaccine to treat advanced prostate cancer developed by Cuban scientists and which expanded its clinical trial in 2019.

Another example, the researcher points out, is the terapia del bacilo from Calmette-Guérin (BCG) which is used to treat bladder cancer “by injecting an attenuated virus similar to tuberculosis to generate an immune response that attacks the tumor.”

A different disease in each person

Another major obstacle to cancer vaccination is that the disease is different in the genome of each person, unlike what can happen with a virus such as the coronavirus that is universal.

With cancer, Pío explains that the DNA damage of each person changes and something specific to that tumor is needed to make a vaccine, for example, there is no universal antigen for all lung cancers.

“Not only are no two cancers the same, but in the same person it evolves,” says the researcher, which is why there are treatments that stop working after a while in some patients. “You can never say never in science but it seems difficult that the alterations of a specific tumor can be sequenced to design a universal vaccine.”

Research is advancing towards personalized oncology medicine, thanks to the development of knowledge about the human genome and technologies that allow sequencing of specific alterations for each patientPío explains.

The key to all these advances – which are encompassed in the field of immunotherapy – is to understand how the body’s defenses respond to the attack of tumor cells. Vaccines are just one of their strategies, Pío says.

Hope in the immune system

Cancer has been the leading cause of death in the last half centuryJapanese immunologist Tasuku Honjo began his acceptance speech for the Nobel Prize in Medicine, and the trend worsens even more as average life expectancy increases.

Reside in decipher the secrets of our sophisticated immune systems may this prognosis not be grim.

This is how Hojo explained it when he received the highest award in the field of Medicine in 2018 for his advances in the treatment of cancer through immunotherapy:

How could we develop such a sophisticated immune recognition system that it employs genetic rearrangement? The genetic rearrangement mechanism must have developed accidentally, probably about half a billion years ago, when vertebrates evolved. From then on, it must have persisted through natural selection due to the advantage of surviving infectious diseases. “

And he concludes: “Considering that the probability of such a mutation and selection must be incredibly low, human beings are very lucky“.

Advances in Medicine focus on our luck as a species one day being able to immunize us against all types of cancer.