The Covid-19 vaccine developed by Oxford University in partnership with pharmaceutical company AstraZeneca could facilitate the establishment of immunity against cancer.
In tests in mice, the candidate vaccine was able to increase levels of cancer-fighting cells and improve the effectiveness of treatment against the disease. The results were published in the Journal for ImmunoTherapy of Cancer.
The Oxford/AstraZeneca vaccine against the new coronavirus uses a technology called a nonrecurrent viral vector, which aims to stimulate an immune system response and generate protection against disease. The immunizing agent is based on a genetically modified chimpanzee adenovirus, incapable of harming humans, with a gene for the novel coronavirus S protein (spike) protein.
Based on the knowledge gained in creating the vaccine that has been widely used in Brazil, Oxford researchers are working to develop an immune agent aimed at treating cancer. The candidate vaccine, which is still in preclinical testing with animal participation, also uses vector technology with a two-dose initial dose regimen.
Vaccine + Immunotherapy
According to the study, the vaccine showed positive results when used in conjunction with immunotherapy, which is a treatment method against cancer that relies on inducing the patient’s immune system to fight cancer cells. The treatment is different from the methods of chemotherapy and radiotherapy, for example, which attack cancer cells directly.
Although immunotherapy is promising, it may have low efficacy for some patients, especially those with low levels of tumor-fighting cells in the body.
“Immunotherapy will only work if the patient has the correct immune system cells, in which case it will be CD8+ cells, which attack the tumor and defend our body. In cancer patients, these cells are often reduced by the tumor,” explains Brian Eric Strauss, Research Coordinator at the Virus Vector Laboratory of the Center for Transformational Research in Oncology (CTO) of the São Paulo State Cancer Institute (ICSP).
In this context, the Oxford vaccine technology enters, which generates strong responses from certain defense cells in the body, called CD8 + T lymphocytes, which are necessary for good effects against tumors.
Experimenting with Oxford/AstraZeneca immunogens, researchers have developed a potential two-dose therapeutic vaccine with different primary and supportive viral vectors, including the Covid-19 vaccine vector.
Preclinical trials in mice showed that the vaccine increased levels of CD8+ T cells, which infiltrate the tumor, and amplify the response to immunotherapy. The combination of vaccine and immunotherapy resulted in a greater reduction in tumor size and improved animal survival compared to immunotherapy alone.
“If you stimulate the immune system and increase CD8+ cells, freed from the inhibitory effect caused by the tumor, thanks to the effect of immunotherapy, there will be a greater effect against the disease,” explains researcher Luis Fernando Lima Reyes, director of education. and research at Sírio-Libanês Hospital in São Paulo.
Vaccine recipe
Vaccines can be produced using different technologies. However, the goal is the same: to provide the immune system with information related to the body’s harmful agent, which can be a virus, bacteria and even a tumor, so that the defense system produces specific cells and antibodies to fight. against this agent.
To craft an immune system that specifically targets cancer cells, the researchers focused on two types of proteins found on the surface of different types of cancer cells, called MAGE.
An antigen is a bait that shows the immune system how to attack a tumor. It’s similar to what’s done in the Covid-19 vaccine, which uses the Spike protein as information the immune system needs to find a target and get rid of the coronavirus. In the case of cancer, this antigen is a protein that cancer cells have that normal cells don’t have,” explains Brian.
According to the researcher from ICESP, using proteins found in a variety of tumors as a prescription for an immunizing agent allows a vaccine candidate to use it in the future to fight different types of cancer.
For Brian, developing a vaccine against cancer faces challenges such as searching for an appropriate antigen that does not cause adverse effects in patients and is able to activate the immune response.
Finding the right antigen to use in a vaccine is problematic. In the case of Covid-19, for example, it is very clear. With cancer, this is very complicated because we have thousands of different proteins and you never know which patient will express any of these proteins, which vary from person to person,” he explains.
According to the University of Oxford, next steps in the research include conducting a phase I and II clinical trial of a cancer vaccine in combination with immunotherapy. The study, which should include 80 lung cancer patients, is due to begin at the end of this year.
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