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Switch off a gene of your choice

This piece from Works in Progress argues that we are standing on the precipice of a medical revolution, not through the discovery of new drugs, but through the ability to simply turn off the genes that cause disease. It suggests that decades of struggle in traditional drug discovery are finally being bypassed by a technology that treats the body's instructions as editable code rather than immutable fate. For busy leaders tracking the future of biotech, this is not just a scientific update; it is a signal that the most intractable diseases may soon be manageable with a quarterly injection rather than a lifetime of complex regimens.

The End of the "Undruggable" Era

The article opens with a stark metaphor for the current state of pharmaceutical research, describing it as "a boot stamping on a biologist's face" where the boot is labeled "medicinal chemistry." This vivid imagery sets the stage for the central problem: traditional small-molecule drugs rely on finding a specific "pocket" on a protein to bind to, a process that fails for the vast majority of human proteins. Works in Progress notes that "the majority of human proteins are considered 'undruggable'... either because those proteins lack a convenient pocket for drugs to attach to or because they are 'intrinsically disordered'."

Switch off a gene of your choice

The piece argues that this limitation has forced researchers to focus only on the easy targets, much like "the proverbial drunk searching for his keys under the streetlamp because that's where the light shines." This framing effectively highlights the inefficiency of the current paradigm. By shifting the focus from designing chemicals to fit proteins, to designing molecules that destroy the instructions for making those proteins, the field bypasses the structural limitations that have stalled progress for decades. This is a profound shift in strategy, moving from physical blocking to genetic silencing.

"If the mRNA is destroyed, the protein won't be built. That's exactly what siRNA, or 'small interfering RNA', does: it's a short strand of RNA that interferes with the production of protein by destroying mRNA."

The historical context provided is particularly compelling. The technology emerged not from a grand design for human medicine, but from a botched experiment with petunias in 1990. Scientists at DNA Plant Technology Corporation were trying to make flowers darker by adding extra pigment genes, only to find the flowers turned white. As the editors explain, "Adding an extra copy of a gene for an enzyme would mean more enzyme and therefore more pigment. But somehow, the extra copy eliminated the enzyme's production, rather than boosting it." This accidental discovery of "cosuppression" revealed a natural mechanism where cells use small RNA strands to silence genes, a process that was later validated by Nobel laureates Andrew Fire and Craig Mello. It serves as a reminder that some of the most transformative medical breakthroughs come from understanding nature's own error-correction systems.

Solving the Delivery Puzzle

The core of the argument, however, is not the mechanism of silencing, but the decades-long struggle to deliver the silencer to the right cells. The piece details why simply injecting RNA is futile: "If you just injected siRNA into a patient's veins, nothing useful would happen." The body's enzymes destroy unprotected RNA, and even intact molecules cannot easily enter cells or escape the digestive compartments within them.

Works in Progress traces the evolution of delivery systems, noting that while viruses were an obvious candidate, they carry significant risks of immune reaction. Similarly, early lipid-based carriers struggled with toxicity or inefficiency. The breakthrough came with "ionizable lipids," which are neutral in the bloodstream but turn positive inside the acidic environment of a cell's endosome, destabilizing the membrane and releasing the payload. This chemical ingenuity allowed for the first FDA-approved siRNA drug, patisiran, which treats hereditary transthyretin amyloidosis. The editors note that this drug "needed to be dosed every three weeks," highlighting that while the problem was solved, the solution was still cumbersome.

The narrative then pivots to a more elegant solution that emerged from the same research lineage. Instead of relying on complex carriers, researchers began chemically modifying the RNA itself to make it durable enough to survive "naked" in the bloodstream. By swapping reactive oxygen atoms for stable fluorine or hydrogen, they created molecules that could persist indefinitely. To target the liver specifically, they attached a "sugar molecule called GalNAc," which acts as a homing beacon for liver cells. The result was a dramatic improvement in patient convenience and safety. As the piece states, "Patisiran, which is carried by a lipid nanoparticle, needed to be dosed every three weeks. In contrast, Alnylam's newer drug, vutrisiran, a naked siRNA drug attached to a GalNAc sugar, is approved to treat the same medical condition, but needs to be dosed only once every three months."

This transition from complex, frequent dosing to a simple, quarterly regimen represents a massive leap in the viability of gene therapies. It transforms a treatment from a medical burden into a manageable routine. Critics might note that this success is currently limited almost exclusively to the liver, as the GalNAc receptor is abundant there but rare elsewhere in the body. The article acknowledges this, noting that "every success story so far has involved the liver," and that expanding this technology to the brain or muscles remains the next great frontier.

"Simply put, temporarily switching off a precise gene in the liver is now a solved problem, and it can be achieved with drugs that require no more than four administrations per year."

The implications for public health are staggering. The editors point out that this technology is already being applied to high cholesterol, hemophilia, and acute hepatic porphyria, with trials underway for hypertension and diabetes. The ability to silence a gene that causes high blood pressure could potentially prevent strokes and heart attacks before they occur, shifting medicine from reactive treatment to proactive prevention. This aligns with the broader historical trend seen in other biotech sectors, such as the development of intrathecal administration techniques which allowed drugs to bypass the blood-brain barrier, proving that delivery hurdles are often the only thing standing between a hypothesis and a cure.

Bottom Line

The strongest part of this argument is its clear demonstration that the "undruggable" label is no longer a biological fact but a technological limitation that has been overcome for a specific class of diseases. The piece effectively reframes the history of drug discovery, showing how a failed petunia experiment led to a solution that could treat dozens of deadly conditions. However, the argument's biggest vulnerability lies in its optimism regarding non-liver targets; until delivery systems can be perfected for the brain or heart, the revolution will remain partial. The reader should watch for the next wave of clinical trials that attempt to break the liver's monopoly on siRNA success, as that will determine whether this technology truly changes medicine as we know it.

Deep Dives

Explore these related deep dives:

  • DNA Plant Technology

    This company's failed attempt to deepen petunia pigment by adding gene copies accidentally discovered the phenomenon of RNA interference, providing the accidental origin story for the entire field.

  • Asialoglycoprotein receptor

    This specific liver receptor is the critical biological 'doorway' that allows synthetic siRNA molecules to enter hepatocytes, solving the delivery problem that previously made the therapy impossible.

  • Intrathecal administration

    The article contrasts the difficulty of systemic drug delivery with the invasive necessity of injecting therapeutics directly into the spinal fluid to treat neurological conditions like Huntington's.

Sources

Switch off a gene of your choice

This piece is featured in Issue 25 of Works in Progress. Subscribe today to get an issue every two months delivered straight to your door.

Jacob Witten explains why siRNA will change medicine as we know it.

If you want a picture of biomedical research, imagine a boot stamping on a biologist’s face – for decades. The boot is labeled ‘medicinal chemistry’. This should not be taken as an insult to medicinal chemists, who heroically navigate maybe the hardest field in biomedicine.1 Rather, what I mean is this. A biologist might have a clear hypothesis about how to stop a disease, such as: blocking a particular protein will lower blood cholesterol and reduce the risk of heart disease. Naturally enough, the biologist would like to test that hypothesis. But there is no magic button to switch off this protein; something physical has to do the blocking. Usually, that thing is a small chemical carefully designed to be administered into the body, bind to the protein, block it – and do nothing else. In practice, this almost never goes as planned, which is a major reason most drugs fail in clinical trials.

It’s worse than this: medicinal chemists struggle to come up with ways to interact with most proteins at all. The majority of human proteins are considered ‘undruggable’, meaning that none of the small molecules we can currently synthesize can effectively bind to them, either because those proteins lack a convenient pocket for drugs to attach to or because they are ‘intrinsically disordered’, with little coherent structure.2 Drug discovery ends up focusing on the minority of targets that are druggable, like the proverbial drunk searching for his keys under the streetlamp because that’s where the light shines.

Even for those targets, success is far from guaranteed. A drug that works in the lab might be broken down in the body before it reaches its target protein, interfere with other proteins and cause toxic side effects, or fail to be absorbed and distributed to the right tissues. Our ability to predict what small molecule drugs will do in the body is so poor that even if the drug works, it might be for a different reason than originally hypothesized!3

But what if, instead of spending years optimizing small molecule chemistry to treat just one disease, and all that work merely delivering a sharp reminder that no plan survives first contact with ...