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Ivan Pourmir (medical oncologist)
Moderna and Merck Laboratories announced on December 13 a very encouraging first result of their mRNA vaccine against melanoma. It would reduce the risk of relapse or death by 44%! An important step towards a cancer vaccine? The opinion of our expert, Dr. Yvan Pourmir, oncologist and researcher in immunology.
The RNA vaccine is back in the spotlight and, no offense to its opponents, with excellent news. In a press release, the American laboratories Moderna and Merck announced on December 13 positive preliminary results for their messenger RNA vaccine under development against melanoma, an aggressive skin cancer. According to their announcement, out of 150 people with stage 3 or 4 melanoma, taking the vaccine along with the cancer drug Keytruda (immunotherapy) reduced the risk of the cancer coming back and dying by 44%. compared to people only treated with the anti-cancer drug.
This new messenger RNA vaccine is personalized for each patient. It works from DNA taken via a tumor biopsy. Next, the cancer sample is analyzed and mutations in the tumor cells called neoepitopes identified. Moderna selects several dozen neoepitopes that it believes would generate the strongest immune response in a patient, and inserts the genetic codes of these neoepitopes into a vaccine.
Just like the covid vaccine, this vaccine uses messenger RNA. Once inside the body, the mRNA instructs the patient’s cells to make the neoepitopes. Which is supposed to trigger an immune response that can better target and destroy cancer cells. The present vaccine is administered in nine doses every three weeks, as well as a course of Keytruda every three weeks.
A big step in the fight against cancer?
“We will begin additional studies in melanoma and other forms of cancer, with the goal of providing patients with truly individualized cancer treatments. We look forward to publishing the full dataset and sharing the results at an upcoming oncology medical conference, as well as with health authorities.” announce the laboratories.
On the strength of this success, they wish “rapidly” the approval of a final phase clinical trial which would confirm the effectiveness of the vaccine on a much larger group of patients. If the study confirms the good results, the melanoma vaccine could be approved within six months. The companies also plan to test the vaccine on other cancers.
The good idea of combining immunotherapy and vaccine
Consulted on the subject, Dr. Yvan Pourmir, oncologist and researcher in immunology, gives us a slightly more medical point of view of this stage, far from the media hype and the effects of the announcement of American laboratories.
“This idea of a cancer vaccine is not new. The principle is similar to that against infectious diseases, except that in an RNA vaccine, it is a question of educating the immune system against something already in place and not in a preventive way. This is called adaptive immunity. The goal is for the immune cells to recognize the antigens, specific to the tumor cells”.
Many attempts have been made, all of which have ended in failure so far.
“In therapy alone, anti-tumor vaccines resulted in failures, because complementary elements, immune checkpoints, prevented them from acting. The fact of combining an anti-tumour vaccine with immune checkpoint inhibitors is promising and allows a priori results. This is the strength of these associated companies, Moderna which makes vaccines and Merck which produces a very popular immunotherapy treatment” he explains.
Special attention should be paid to side effects
The researcher, on the other hand, has two reservations about this announcement of an mRNA vaccine against cancer:
“On the one hand, as researchers, I am not convinced by the procedure which uses injection and immunotherapy as an adjuvant treatment, ie after melanoma surgery. I think it would be more effective to use it as a “neo adjuvant”, starting before the operation. Because in the tumor there are interesting and necessary immune structures to activate the immune response”.
Finally, according to him, the question of side effects is covered in the press release offered by Moderna.
“In the proposed one-year treatment, we can legitimately worry about side effects such as myocarditis already encountered in vaccines against covid (also stamped Moderna), knowing that it is also a risk in immunotherapies against cancer. It should be noted that this vaccine is individualized to produce personalized RNA (this is understandable because each cancer does not present the same antigens), but this also means that there will be as many products as there are different patients. .with the effects that go with it”.