It is a dream of millions of patients and doctors: a vaccine against cancer. The American laboratories Moderna and Merck have just successfully tested a therapy against relapses of skin cancer. In patients with this disease, treatment generally consists of removing the tumor, the melanoma, and then giving immunotherapy for a year, that is to say a drug that will help the immune system to detect and fight cancer cells which could redevelop and lead to a relapse.
In the clinical trial proposed here, the idea is to combine this treatment with a second, this time totally personalized since it is made from the patient's tumor cells. More than 1,100 patients were followed, some receiving dual treatment, and others receiving only immunotherapy. According to the two laboratories, the risk of recurrence was significantly reduced in patients in the first group.
So is there hope? Suzette Delaloge, oncologist and president of the board of directors of the National Cancer Institute, details this progress for franceinfo.
franceinfo: how do you analyze these first results?
Suzette Delaloge: I think that a priori these are very interesting results. The precise data have not yet been presented and they will be presented, I think, at the European Cancer Congress in two months. So, we only have the announcement, but we had very solid preliminary data and it is a very well-conducted clinical study, in which France participated extensively, which gives us real hope. It is a completely innovative, very interesting medicine.
This is to slow down the occurrence of a possible recurrence. For the oncologist that you are, is this already a big step?
In fact, it's huge. These are people who have a melanoma, therefore a skin tumor, which in certain cases presents in a form that is either locally advanced or with lymph node involvement. These were not people who had a very small, very localized melanoma, they were a slightly more advanced melanoma. And in fact, in these cases, there may be a risk of relapse in the form of metastases, which can be lethal. This risk can be up to 30%.
Currently, we have already implemented immunotherapy. By giving this immunotherapy, we reduce the risk of relapse in the form of metastasis of this melanoma. And there, this study compares either standard immunotherapy alone, or immunotherapy combined with a vaccine. It is a very original vaccine since, based on data from each person's tumor, we will design the vaccine which will recognize up to 34 antigens specific to the person's tumor, and make it possible to educate their immunity to avoid relapse.
Very concretely, how does this happen? Should we remove part of the tumor?
In fact, we will sequence the DNA of a small fragment of the tumor. It's something we really do routinely. From there, we will identify abnormalities in the tumor's DNA, which we know can constitute antigens very easily recognized by the immune system.
We will build a vaccine from these small proteins which will allow immunity to be educated by saying to ourselves: “If I encounter these proteins in the future, it is abnormal and I will kill the cells which carry them.” These proteins are specific to cancer and are not present, or exceptionally present, on other cells.
Is it easy to reproduce a vaccine on a large scale that will be different for each person?
This is what was done in this study. There were just over 1,100 people who participated. So, we don't have all the data yet, but in the preliminary study which was very interesting and for which we have 5 years of follow-up, there was a reduction in the risk of relapse of around 50%, which is still enormous. There was a tendency to say that maybe this could improve overall life expectancy — we'll have the results in a long time for the big study.
In any case, it was doable. That is to say that there were 85% of people entering the preliminary study for whom we were able to designate the personal vaccine. It's not 100%, we'll see what that gives for the study presented here, but it's still quite remarkable. And then, our technologies evolve. It is an RNA vaccine that has been built for several years now; we really have experience that it works, we can do it.
Can we imagine treating other cancers with this type of vaccines?
With this approach developed by these two laboratories, there are other large studies underway around the world, in other pathologies. For the moment, they are focusing more on very “immunomediated” pathologies, that is to say which are quite sensitive to immunotherapy. For some cancers, it is much more difficult to wake up immunity. These are cancers that we call “cold”, that is to say which have few neo-antigens or for which immunity is very extinguished.
However, studies are underway for different cancers, including bladder or lung cancer for example. So yes, this will happen for other cancers. It's a little more difficult for breast cancer type cancers.
