The results of the international MAPPYACTS study, co-funded by Imagine for Margo, have just been published. They lay the foundations for access to precision medicine for young children with cancer when conventional treatment has failed. A real hope for all our little warriors who are fighting against the disease. Birgit Geoeger from Gustave Roussy (France) and Gudrun Schleiermacher from the Institut Curie (France) explain this project to us.


Precision medicine is a term that has replaced personalized medicine. It is used to describe this approach aimed at adapting the therapeutic strategy according to the patient.

In the case of cancers, and more particularly those in children and teenagers, precision medicine will intervene in the event of failure of so-called “standard” treatments: chemotherapy, surgery or radiotherapy.

Indeed, in these cases, new therapeutic approaches will have to be found. For this, we will analyze and interpret more precisely the molecular profile present in the patient’s tumor in order to find the alterations that are responsible for the disease.

From there, we propose to adapt the treatment in order to target the various alterations in order to increase the chances of recovery for children and teenagers.


In other words, precision medicine consists in providing, for a given patient, a personalized therapeutic strategy specific to the characteristics of his/her disease. Our goal in doing this research is to provide therapeutic sessions that better target the disease. 


The first advance of MAPPYACTS is to have determined the feasibility and importance of molecular sequencing. By studying the latter in 787 patients, it was possible to find in 69% of them, one or more abnormalities likely to be specifically targeted by a new drug. 30% of patients were able to benefit from a therapeutic approach targeted at the anomaly. More than half (57%) of these innovative treatments were administered as part of a clinical trial, including 72% in the European AcSé-ESMART study, which was conducted in parallel. It is also thanks to this joint evolution that we have recorded such a high rate of therapeutic reorientation. Usually we were at 10%. The combination of AcSé-ESMART and MAPPYACTS has opened up the chances of specific treatments for patients.

Then, the second achievement of MAPPYACTS is in what is called “circulating DNA”. Indeed, the study demonstrated that it was possible, in certain types of cancer such as neuroblastoma, to find molecules of the tumor in the blood. If this had been proven for many years in the context of leukemia, solid tumors were not concerned.

This discovery opens the door to a new technique, which can, in some cases, replace biopsy in order to follow the evolution of a tumor. It could therefore also become a means of predicting the risk of relapse and therefore of adapting the follow-up of the child. It is important, once again, to mitigate this new technique; for the moment it is a practice under examination which will be studied in MAPPYACTS 2.

Although there is still a long way to go, the results of MAPPYACTS therefore offer hope for many children and teenagers who are fighting against the disease.


In concrete terms, MAPPYACTS has shown us that for a certain number of patients, unfortunately still a minority, thanks to sequencing, it is possible to treat molecular alterations and therefore the “driver” of the tumor as soon as the diagnosis is made or during a treatment failure.

For other patients, the disease being more complex, it is important to continue research in order to always be able to treat children better and more.


The first step is to make sequencing a success. Today, we know that sequencing is vital. But if we only have the latter without the treatments, then it will not directly serve the child concerned. In addition, we must also observe how the immune system responds to the disease in order to help treatments to better fight the disease.

Even if medicine has made progress, it is not enough for most children whose treatment fail and that is why we must continue to accelerate research by reinvesting in both MAPPYACTS 2 and ESMART. The objective, to develop new ideas and continue to heal children more and better.

The second step is that thanks to MAPPYACTS, we have opened the door to a preventive exploration of follow-ups and long-term treatments via the circulating DNA technique. It is now a question of confirming the hypotheses for all children and teenagers with cancer.