They lived. Their survival was indistinguishable from healthy mice.
In the quiet corridors of a research institute, two scientists from unrelated fields stumbled into a discovery that may rewrite the fate of patients born with a disease that has never had a treatment. A small molecule called N-PPG, originally explored for cancer and neurodegeneration, has now demonstrated the ability to completely prevent kidney failure and restore normal survival in mice with primary hyperoxaluria type 2 — a rare genetic disorder that currently leaves roughly 1,700 Americans with no options beyond transplant or dialysis. The finding, published in Kidney International, reminds us that the boundaries we draw around scientific disciplines are often more arbitrary than the problems they are meant to solve.
- Infants and young adults with PH2 face relentless kidney destruction with no approved therapy — until now, their only lifelines were transplant or dialysis, both temporary and incomplete.
- In six-month mouse trials, every untreated PH2 animal died of kidney failure within 15 weeks, while every animal given daily oral N-PPG survived the full study period with healthy kidneys.
- The drug operates on two fronts simultaneously: it cuts off excess oxalate production at its enzymatic source while also fortifying kidney cells through a stress-response mechanism called mitohormesis.
- No significant side effects — no organ damage, no weight loss, no behavioral changes — have emerged across multiple mouse studies, including those running half a year.
- The discovery was not planned; it emerged from cross-disciplinary conversation between a cancer researcher and a neuroscientist sharing lab space, a reminder that scientific breakthroughs often live at unexpected intersections.
- Human trials remain on the horizon pending pharmacokinetic and expanded safety studies, but the research opens potential treatment pathways for PH3 and common recurrent kidney stone disease as well.
At the Buck Institute for Research on Aging, a chance collaboration between scientists working on entirely different diseases has produced the first real therapeutic hope for patients with primary hyperoxaluria type 2 — a rare genetic disorder that destroys kidneys and has no cure. The compound at the center of this discovery is N-propargylglycine, or N-PPG, a small molecule that completely prevented kidney stone formation and restored normal survival in mouse models of the disease.
PH2 affects roughly 1,700 diagnosed Americans, though the true number is likely higher due to underrecognition. The disease causes the liver and kidneys to overproduce oxalate, which crystallizes into calcium oxalate stones that progressively destroy kidney function. It can strike in infancy or young adulthood, and its trajectory is unrelenting. Kidney transplant and dialysis exist as stopgaps, but no drug has ever been shown to address the underlying biology — until now.
The path to this discovery was indirect. Gary Scott, a cancer researcher, was studying N-PPG for its ability to trigger mitohormesis — a mild cellular stress response that paradoxically strengthens cell function. His colleague Lisa Ellerby, a neuroscientist studying Huntington's disease, wondered if the same mechanism might protect neurons. As they explored the compound's biochemistry together, they noticed it was interfering with the metabolic pathway responsible for oxalate overproduction. That observation redirected their work entirely.
The mouse studies were decisive. In a three-week trial, N-PPG dramatically reduced urinary oxalate and nearly eliminated stone formation. In a six-month survival study, untreated PH2 mice died at a median of 15 weeks; treated mice survived all 24 weeks with kidney function and body weight indistinguishable from healthy animals. The drug is taken orally, distributes throughout the body, and has produced no significant side effects across all studies conducted to date.
N-PPG works through two mechanisms: it blocks PRODH2, the enzyme driving excess oxalate production, and it induces mitohormesis, building the kidney's resilience against damage. Researchers are already developing chemical variants to isolate which properties matter most. The drug may also prove effective against PH3 and common recurrent kidney stones, given the shared metabolic pathways involved.
Pharmacological and expanded safety studies must precede any human trials, and the road from mouse to patient is never short. But for those living with PH2, this research offers something that has never existed before: evidence that the disease can be stopped, and that the right molecule, found in the right conversation, can change what survival means.
In a laboratory at the Buck Institute for Research on Aging, scientists have identified a small molecule that does something previously thought impossible: it completely stops kidney stones from forming in mice engineered to carry primary hyperoxaluria type 2, a rare genetic disease that has no treatment and no cure.
The compound, called N-propargylglycine or N-PPG, works by blocking an enzyme in the liver and kidneys that produces excess oxalate—a chemical that crystallizes into calcium oxalate stones, the kind that destroy kidney function and eventually kill. About 1,700 Americans are diagnosed with PH2, though researchers suspect the true number is much higher because many cases go unrecognized. The disease strikes infants and young adults without warning. It progresses relentlessly. The only options available now are kidney transplant or dialysis, and even those are temporary measures. This discovery, published in Kidney International, represents the first real therapeutic hope these patients have ever had.
The path to N-PPG was unexpected. Gary Scott, a senior scientist studying breast cancer, was sharing lab space with Lisa Ellerby, a neuroscientist focused on Huntington's disease. Over coffee or in passing conversation, they began talking about their work. Scott mentioned he was investigating N-PPG as a potential cancer agent because it seemed to trigger a cellular response called mitohormesis—a small amount of stress that paradoxically makes cells function better. Ellerby wondered if the same mechanism might help neurons damaged by Huntington's. They tested it. The compound corrected about half the gene expression problems associated with the disease. As they dug deeper into the biochemistry, they realized N-PPG was affecting the metabolic pathway that produces oxalate. That observation opened a door neither of them had anticipated walking through.
The mouse studies were striking. In a three-week trial, N-PPG reduced urinary oxalate levels dramatically and nearly eliminated stone formation. The treated mice showed far less kidney damage and preserved kidney function compared to untreated animals, whose kidneys filled with stones and failed. But the six-month survival study was the one that mattered most. Untreated mice with PH2, fed a diet high in hydroxyproline to mimic the human disease, lived a median of 15 weeks before dying of kidney failure. Nearly all of them died. The mice treated daily with oral N-PPG survived all 24 weeks of the study. Their survival, weight, and kidney function were indistinguishable from healthy mice. They lived.
What makes N-PPG particularly promising is its dual mechanism. It blocks PRODH2, the enzyme that generates excess oxalate in the first place, cutting off the problem at its source. But it also induces mitohormesis—it strengthens the kidney's ability to resist damage. The drug is taken by mouth, penetrates tissues throughout the body, and in all the mouse studies conducted so far, including those lasting six months, it has caused no significant side effects. No organ damage. No weight loss. No behavioral changes.
The implications extend beyond PH2. Because PH3, another form of primary hyperoxaluria, depends on the same metabolic pathway, N-PPG may work for that disease too. And because the mitohormetic effect strengthens mitochondrial resilience generally, the drug might eventually prevent the more common forms of recurrent kidney stones that affect thousands of people each year. Researchers are already developing chemical variants of N-PPG to better understand which of its properties matters most for kidney protection.
Before any patient receives this drug, more work remains. Pharmacokinetic studies are needed to understand how the body absorbs, distributes, and eliminates N-PPG. Safety studies must be expanded. The path from mouse to human is long and uncertain. But for the first time, patients with primary hyperoxaluria type 2 have something to point to: evidence that their disease is not inevitable, that the damage can be stopped, that survival is possible. The discovery also speaks to something less tangible but equally important—what happens when researchers from different fields, studying different diseases, share space and remain open to conversation. Scott and Ellerby were not looking for a kidney stone cure. They found one anyway.
Notable Quotes
We became quite excited about that, generating our interest in a completely different field: nephrology. It's a fun collaboration and it shows what can happen when your next-door neighbor is open and receptive.— Gary Scott, senior scientist at Buck Institute
N-PPG appears to be an amazing drug candidate, not just because it's orally bioavailable and penetrates many different tissues without producing any side effects, but its mitohormetic properties may extend its utility to prevention of more common forms of recurrent kidney stone disease.— Christopher Benz, Buck Institute professor and oncologist
The Hearth Conversation Another angle on the story
Why does this matter so much for such a small number of people—1,700 in the whole country?
Because for those 1,700, there is literally nothing else. No approved treatment. No option except transplant or watching your kidneys fail. Imagine being a parent of a child diagnosed with this. Right now, you have no hope. This changes that.
How did two cancer and neurology researchers end up solving a kidney disease problem?
They were neighbors in the lab. Scott mentioned his work on N-PPG, Ellerby thought it might help Huntington's patients, they tested it, and when they looked at the biochemistry, they realized it was affecting oxalate production. It's the kind of discovery that only happens when people are talking to each other across disciplines.
The mice treated with N-PPG survived the full study while untreated mice died. That's a huge difference. Why should we be cautious about that result?
Mouse studies don't always translate to humans. The dosing might be different. Side effects might emerge that weren't visible in six months of mouse treatment. The human body is more complex. But it's a genuine signal of efficacy, not a marginal improvement.
You mentioned the drug has a dual mechanism—blocking the enzyme and inducing mitohormesis. Which one actually matters more?
That's what they're trying to figure out now. The blocking of the enzyme stops oxalate production. The mitohormesis strengthens the kidney's ability to handle stress. Both seem important, but they don't yet know which is doing the heavy lifting.
What's the timeline before patients could actually take this?
Years, probably. They need safety studies, pharmacokinetic studies, then regulatory approval, then clinical trials. This is not something that will be available next year. But for a disease with no treatment, the fact that there's a clear path forward is itself significant.