An unprecedented clinical trial funded by the American federal authorities has shown that it is possible to identify breast cancer patients likely to see their disease recur, and to effectively treat the dormant cells responsible for relapses. There is not even a question of developing a new treatment, since existing drugs do the job very well.
Researchers from the Abramson Cancer Center and the Perelman School of Medicine at the University of Pennsylvania (United States) published their results in the journal Nature Medicine. They explain that although the chances of survival from breast cancer have significantly improved over the last decades, relapses still represent a therapeutic impasse: once the cancer returns, there is no possible cure, only treatments intended to contain it.
Nearly 30% of patients will experience a recurrence, sometimes only a few years after the initial diagnosis, sometimes several decades later. Until now, no tool has made it possible to identify patients carrying these dormant cells in real time.
The phase 2 clinical trial, carried out on 51 women who completed their treatment, provides initial proof of feasibility. In 80% of cases, the drugs tested eliminated dormant tumor cells. After a 42-month follow-up, the relapse-free survival rate reached more than 90% in patients receiving a single drug, and 100% in those treated with the combination of two molecules.
These dormant cells, also called “minimal residual disease” (MRD), escape imaging tests because they do not behave like active cancer cells. However, they can reactivate years later and cause incurable metastases. It is this silent phase that the researchers chose to target. “Our study shows that monitoring and eliminating dormant tumor cells is a promising strategy to prevent relapse”analyzes lead researcher Angela DeMichele.
Review how to manage “after”
The scientists relied on preclinical work carried out in the laboratory and in mice. The team of biologist Lewis Chodosh had, for example, shown that two drugs already approved by the American Food and Drug Administration (FDA) for other indications could prolong survival by eliminating residual cells. Notable fact: these molecules prove to be ineffective against active cancers, but act on dormant cells.
In the clinical trial, participants whose bone marrow still contained tumor cells after standard treatment were divided into three groups: one receiving one drug alone, the second the other drug, and the third both combined. After six to twelve months of treatment, the dormant cells had disappeared in most patients.
At this point, only two relapses have been observed after three and a half years of follow-up. However, the team is careful not to draw hasty and definitive conclusions: the trial remains limited in size and must be confirmed on a larger scale. Two other phase 2 trials are already underway in several American centers to test these results on a larger sample of patients.
Beyond medical results, the study aims to change clinical practice. Today, after complete treatment for breast cancer, follow-up largely consists of waiting for possible signs of relapse. Researchers hope to move this cursor towards early treatment, based on systematic screening of these dormant cells and rapid intervention in the event of detection.
For patients, the psychological impact could be as important as the medical impact. The anxiety of relapse persists long after treatment has ended and the prospect of finally being able to identify and reduce this risk opens the way to a new way of considering life “after” breast cancer.
