Using tiny strands of synthetic DNA, University of Geneva researchers have built a drug system that activates only on cancer cells. The approach could lead to programmable, “smart” medicines that spare healthy tissue.
For decades, one of the toughest problems in cancer treatment has been how to kill tumor cells without harming the healthy tissue around them. A team at the University of Geneva believes it has found a powerful new way forward, using synthetic DNA to build “smart” drugs that switch on only where they are truly needed.
The researchers have designed a drug delivery system made of small DNA strands that can recognize cancer cells with exceptional precision and release toxic payloads only at the tumor site. Their work, published in the journal Nature Biotechnology, points toward a future of programmable medicines that can make decisions inside the body.
Traditional chemotherapy floods the body with drugs that attack fast-dividing cells, often causing serious side effects. In recent years, antibody-drug conjugates, or ADCs, have offered a more targeted option by using antibodies to ferry drugs directly to cancer cells. But even these advanced treatments have drawbacks, including limited penetration into dense tumor tissue and a cap on how many drug molecules each antibody can carry.
The Geneva team set out to solve those problems by swapping bulky antibodies for much smaller DNA components. Because synthetic DNA strands are tiny and flexible, they can move through tumors more easily and can be engineered to carry and assemble multiple drug molecules.
In their system, separate DNA strands each carry a different piece of the puzzle: two distinct cancer-targeting binders and a powerful cell-killing drug. On their own, these components remain inactive. The key is that they are designed to come together only when they encounter a very specific combination of markers on the surface of a cancer cell.
The process works a bit like two-factor authentication for online banking. One DNA strand latches onto one cancer marker, another strand binds to a second marker, and only when both are present do the DNA pieces start to snap together in a chain reaction. That self-assembly brings the drug molecules into position and concentrates them directly on the tumor cell.
If either cancer marker is missing, the chain reaction never starts and the drug stays off.
In lab studies, the technology was able to pick out cancer cells that displayed the right combination of surface proteins and deliver toxic drugs to them, while leaving nearby healthy cells unharmed. The researchers also showed that they could load different types of therapeutics into the same system, a strategy that could help prevent or overcome drug resistance by hitting tumors from multiple angles at once.
Senior author Nicolas Winssinger, a professor of organic chemistry in the School of Chemistry and Biochemistry at the University of Geneva, noted the work represents a shift in how we think about medicines.
“This could mark an important step forward in the evolution of medicine, with the introduction of a self-operating drug system. Until now, computers and AI have helped us design new drugs. What’s new here is that the drug itself can, in a simple way, ‘compute’ and respond intelligently to biological signals,” Winssinger said in a news release.
The logic behind the system is borrowed from the world of digital electronics. Just as “computers” rely on basic logic operations such as “and,” “or” and “not,” the Geneva team built a molecular version of an “and” gate into their drug design. In this first demonstration, the drug is activated only when two cancer biomarkers are present at the same time, making it highly selective.
In the future, the same DNA-based framework could be expanded to include more complex logic. For example, a drug might be programmed to turn on only if several disease markers are present and certain healthy-cell markers are absent, or to change its behavior depending on signals from the immune system.
That kind of programmable behavior could open the door to truly “smart” medicines that adapt to their surroundings inside the body. Instead of delivering a fixed dose everywhere, treatments could be tailored in real time to each patient’s unique biology, potentially improving effectiveness while minimizing side effects.
The approach is not limited to cancer. In principle, any disease that leaves a recognizable molecular fingerprint on cells could be targeted by similar DNA-based systems. Because the DNA strands are modular, researchers could swap in different binders and payloads to build therapies for a wide range of conditions.
The work was supported by the Swiss National Science Foundation and builds on earlier advances from the NCCR Chemical Biology program. The next steps will likely involve testing how well the DNA-drug assemblies perform in more complex biological models and, eventually, in animals and humans.
If those tests go well, the technology could help transform how doctors deliver some of the most powerful drugs in their arsenal, turning them from blunt instruments into finely tuned tools that seek out disease and leave healthy tissue largely untouched.
Source: University of Geneva