(Montreal) An experimental vaccine given in conjunction with immunotherapy treatment has almost halved the risk of recurrence and death for some patients with metastatic skin cancer, American researchers recently announced.

The mRNA-4157/V940 vaccine teaches the patient’s immune system to identify and destroy melanoma cells after they have been made visible by immunotherapy treatment.

It uses the same messenger RNA technology used to develop the vaccines that eventually tamed the COVID-19 pandemic. It was also developed by Moderna, whose rival BioNTech is working on a similar project.

“I don’t get excited every time something new comes out, but today I find it to be a study that is very significant and very exciting,” commented Dr. Claude Perreault, who is a full professor at the Institute for Research in Immunology and Cancer of the University of Montreal. These are very interesting results. »

Unlike vaccines that have been attempted to fight cancer for the past few decades, he added, this vaccine is the first to use messenger RNA technology, “and I would say that’s a benefit secondary to the COVID pandemic”.

Each dose of the vaccine is formulated based on the individual genetic code of the patient’s cancer cells, with the help of algorithms that predict which genetic mutations are most likely to be recognized by the immune system.

Of all cancers, melanoma is also the one with the most genetic mutations, which probably explains why American researchers have chosen it as a target, said Dr. Perreault.

In the end, around 30 genetic mutations were incorporated into the vaccine.

“This is an important feature of the vaccine,” said Dr. Perreault. The vaccine did not contain normal proteins. It contained RNA that codes for mutant proteins that are only found in cancer cells. »

Previously developed cancer vaccines used proteins that were more abundant in cancer cells, but also present in normal cells, “and that doesn’t work because our immune system is made to react to foreign proteins , not proteins found on normal cells,” he explained.

But this time, the use of RNA as a support for the vaccine and the use of antigens that are only present in cancer cells give birth to much more promising results.

Administration of mRNA-4157/V940 reduced the risk of recurrence or death by 44% compared to immunotherapy treatment alone.

The study focused on patients who had previously had surgery to remove cancerous cells from the lymph nodes or elsewhere. Their risk of recurrence was considered to be at least 50%. About 100 patients received the experimental vaccine and immunotherapy treatment, and 50 others only the immunotherapy treatment.

The cancer came back in 22% of patients who had received both treatments (possibly because the algorithms had chosen the wrong antigens and now need to be tweaked), compared to 40% of patients who had only been treated with immunotherapy.

The development of each vaccine dose, however, requires considerable work, and each dose is only ready after six or eight weeks of effort.

“It seems like a colossal challenge to me,” warned Dr. Perreault. There is quite a margin between doing a study on a small number of patients and bringing this approach to the clinic. »

Beyond the work required to obtain a single dose, it remains to be seen whether the same strategy would prove effective against other types of cancer. Next in line is likely to be lung cancer, which has the second highest number of mutations after melanoma.

On the other hand, breast cancer, prostate cancer and leukemia have so few genetic mutations that the effectiveness of the new vaccine would be surprising, said Dr. Perreault.

But in the end, this is a first step that we can only rejoice in, underlined the specialist.

“It’s very encouraging,” he said. We finally have a strategy that works. After several failures, it will give everyone confidence that cancer vaccinology can work. »

“It seems like a colossal challenge to me,” warned Dr. Perreault. There is quite a margin between doing a study on a small number of patients and bringing this approach to the clinic. »

The vaccine will now undergo a phase III clinical trial with one thousand participants. It could be available in a few years if the results are convincing.

The results of this study were unveiled this weekend at a conference of the American Association for Cancer Research.