For more than 10 years he has been pursuing a goal that seemed very distant, but which now seems a little closer: obtaining a preventive vaccine against cancer.
This Friday, the doctor and researcher leads a study that presents the first promising results of a vaccine against colon cancer in a small group of patients who suffer from a rare disease that makes them 17 times more prone to this disease than the general population. The results of the trial showed that the precancerous lesions had not grown one year after receiving the treatment and, more importantly, no new lesions had appeared.
It is a first indication that the vaccine, Nous-209, can help “prevent cancer before it appears,” as reported this Wednesday in a note by the MD Anderson Cancer Center in Houston, in the United States, where Vilar Sánchez works.
“It is an initial step for the field, but we demonstrate that the development of preventive vaccines against cancer is feasible,” the 46-year-old Madrid doctor explains to EL PAÍS.
The trial focuses on a very small and special population: patients with . This inherited genetic condition affects approximately one in every 270 people, and multiplies their risk of developing recurrent colon cancer throughout their life.
The trial involved 45 patients with this syndrome who, so far, had not developed colon cancer, but had possibly precancerous lesions known as . The Nous-209 vaccine consists of a deactivated monkey adenovirus that carries 209 antigens (proteins) that occur recurrently in tumors of the colon, stomach and endometrium. In theory, this immunization helps the immune system recognize cancer cells.
The vaccine was well tolerated, with no serious treatment-related side effects. All participants developed intense immune responses capable of recognizing and attacking cancer-related targets, and these responses increased further with annual re-administration. In laboratory tests, T cells induced by the vaccine were able to eliminate tumor cells and showed signs of long-lasting immune memory. One year after treatment, researchers saw fewer precancerous lesions and no new advanced polyps in 85% of participants, providing “early evidence that NOUS-209 may help stop cancer before it develops.” The results are published in Nature Medicine.
This vaccine or others similar could be. The tumors that these patients develop are characterized by having two lesions in their DNA known as mismatch repair deficiency and microsatellite instability. This same type of lesions appear in 15% of colon tumors, 20% of endometrium tumors, and 5% of bladder and stomach tumors.
Vilar-Sánchez comments on the implications of the results. “Evidently, the direct applicability is towards the population with Lynch syndrome, which is relatively large, accounting for 3% of all colon tumors.” [hay un millón de pacientes con el síndrome solo en Estados Unidos]. In the future, it would also be applicable for the prevention of these cancers in the normal population. Now what we have to do is identify the risk groups and that is where the trick comes in, because the development of preventive vaccines has to go hand in hand with the development of risk identification strategies. The relevant thing is that we take an important first step for an entire field,” he highlights.
The vaccine has been developed by the Swiss pharmaceutical company Nouscom. The company and the United States medical team are already preparing larger clinical trials in which the effectiveness of the immunization will begin to be compared in trials with randomized control groups to clarify the real effectiveness of the treatment.
Rosario Vidal, from the Spanish Society of Medical Oncology, who has not participated in the study, highlights its value. “The efficacy results are exploratory, since the study is not sized or has sufficient follow-up to draw conclusions in this sense. However, it is an innovative and promising strategy in the prevention of cancer in a selected population that could be extrapolated to the prevention of other tumors with the indicated molecular characteristics. It is a very interesting first step in the use of vaccines in the prevention of cancer that must be confirmed with randomized studies and greater follow-up,” he says.
