Susanna Fletcher Greer, Chief Scientific Officer at the V Foundation, shared on LinkedIn:
“One of the most heartbreaking truths about breast cancer is that even after successful treatment, the disease can return years, even decades, later. Why? Because tiny clusters of cancer cells sometimes “hide out” in places like the bone marrow, lying dormant like seeds buried in the soil.
These “sleeping” cancer cells often don’t cause trouble for years. But given the right conditions, they can “wake up,” grow, and spread, leading to recurrence. We call these dormant cells “disseminated tumor cells” (DTCs). For patients, they represent the shadow of uncertainty: even after finishing treatment, the question remains: could my cancer come back?
To tackle this challenge, the V Foundation grantee Dr. Lewis Chodosh, Chair and Perelman Professor of the Department of Cancer Biology at the University of PennsylvaniaPerelman School of Medicine asked a bold question: could they directly target these hidden cells before they get the chance to wake up?
The Chodosh team tried a set of existing therapies, including drugs like hydroxychloroquine (often used for malaria) and everolimus (a cancer drug), to see if they could shrink or eliminate the pool of dormant cells. The results were striking: in mice, these treatments reduced the number of hidden cancer cells and improved survival.
But would this work in people?
To find out, they launched a clinical study called the CLEVER trial. They enrolled breast cancer survivors who, despite completing their treatment, still had dormant cancer cells in their bone marrow. Patients were given either hydroxychloroquine, everolimus, or a combination.
The outcome is very promising:
- The treatments were safe and well tolerated.
- Patients who received them had fewer dormant cancer cells.
- Most importantly, their chances of staying cancer-free at three years were excellent, over 90%, and 100% for those who received the drug combination.
Why This Matters for Patients
Think of dormant cancer cells as embers after a fire. You may not see flames, but the risk of reignition is always there. Current breast cancer treatments often blast the entire forest with water, meaning everyone gets treated, even those without embers left. That saves lives, but also exposes many women to side effects they may not need.
This study suggests we may be able to do something smarter: identify who still has embers smoldering, then use targeted drugs to put them out before they spark. If larger trials confirm these results, this approach could transform survivorship, offering women not just remission, but peace of mind.
This is an early-stage trial, and more research is needed before these strategies become standard care. But the proof-of-concept is powerful: by hunting down and extinguishing hidden cancer cells, we may be able to prevent recurrence altogether.
For the 3 million breast cancer survivors in the U.S., and millions more worldwide, this work represents a potential shift from watchful waiting to proactive prevention.
Read about this clinical trial here.”
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