A groundbreaking discovery from the Buck Institute for Research on Aging may soon rewrite the medical landscape for patients suffering from Primary Hyperoxaluria Type 2 (PH2), an aggressive and devastating genetic disorder known for causing progressive kidney failure in infants and young adults. A small orally administered molecule, N-propargylglycine (N-PPG), has been shown in a mouse model to completely halt the formation of calcium oxalate kidney stones—a hallmark of PH2 pathology—protect renal function, and restore survival rates to normal levels. This discovery represents a watershed moment for a disease that currently lacks effective treatments and imposes severe morbidity on approximately 1,700 known patients in the United States, with many more potentially undiagnosed globally.
Primary hyperoxaluria is a group of rare hereditary metabolic disorders characterized by the body’s overproduction of oxalate, a metabolic compound that forms insoluble calcium oxalate crystals within the kidneys. These crystals accumulate and cause recurrent kidney stone formation, leading to extensive tubular injury, renal scarring, and eventually end-stage renal disease. Unlike Primary Hyperoxaluria Type 1 (PH1), which now benefits partly from two approved RNA interference therapies, PH2 and PH3 patients remain without viable pharmaceutical interventions. The only available options for these individuals often entail invasive kidney and liver transplantation procedures, underscoring the urgent need for novel therapeutic strategies.
The research conducted at Buck Institute takes a precision approach by targeting the hydroxyproline dehydrogenase enzyme (HYPDH/PRODH2), a mitochondrial catalyst predominantly located in liver and kidney tissues. This enzyme facilitates the first critical step in the catabolic pathway of hydroxyproline, an amino acid primarily derived from collagen turnover. In PH2 patients, faulty metabolism downstream of this step leads to excessive production of glyoxylate, which the body cannot effectively process, culminating in the pathological overabundance of oxalate. By inhibiting HYPDH/PRODH2 activity through administration of N-PPG, researchers successfully suppressed oxalate synthesis at its source, preventing the detrimental precipitation of calcium oxalate deposits in renal tissues.
The genesis of this discovery is itself a story of scientific serendipity and interdisciplinary collaboration. Gary Scott, PhD, a senior scientist focused on breast cancer in the Benz Lab, was exploring N-PPG’s potential as an anti-mitochondrial agent in oncology. Concurrently, neuroscientist Lisa Ellerby, PhD, whose lab investigates Huntington’s and Alzheimer’s diseases, considered the compound’s effects through the lens of mitohormesis—a phenomenon where controlled mitochondrial stress enhances cellular robustness. When N-PPG displayed partial correction of gene expression abnormalities in Huntington’s disease cellular models, the two teams connected the dots linking N-PPG’s metabolic pathway involvement with oxalate production, pivoting their collaborative efforts toward nephrology and rare kidney stone disorders.
In a pivotal initial study lasting three weeks, mice genetically engineered to mimic PH2 were administered N-PPG orally. The results demonstrated a significant decrease in urinary oxalate concentration and a near-complete eradication of calcium oxalate crystal formation. Histological examination revealed substantially reduced tubular damage and better preservation of renal architecture and function in treated animals compared to untreated controls that rapidly accumulated damaging kidney stones and suffered severe renal impairment.
Follow-up long-term survival studies spanning six months reinforced these remarkable therapeutic effects. Untreated PH2 mice maintained on a hydroxyproline-rich diet mimicking the human metabolic environment exhibited median survival times of only 15 weeks, with death primarily resulting from renal failure. Contrastingly, mice receiving daily N-PPG treatment not only survived the full 24-week study period but also maintained normal weight gain and exhibited no decline in kidney function, making them indistinguishable from healthy wild-type mice. This profound survival rescue underscores N-PPG’s potential to transform outcomes in lethal primary hyperoxaluria.
Mechanistically, N-PPG’s appeal rests on its dual action. As Ellerby explains, the molecule not only potently inhibits the PRODH2 enzyme crucial for the generation of oxalate but also triggers mitohormesis. This stress adaptation response boosts mitochondrial resilience within kidney cells, fortifying them against oxidative injury and other nephrotoxic insults. This dual mechanism suggests that N-PPG’s benefits extend beyond simply reducing oxalate burden; it enhances intrinsic renal protection, which could prove invaluable for managing calcific nephropathies and other diseases characterized by mitochondrial dysfunction.
Buck Institute professor Christopher Benz highlights the therapeutic promise of N-PPG, emphasizing its oral bioavailability, broad tissue penetration, and striking safety profile observed in multiple preclinical studies. No significant side effects were reported even after six months of continuous administration in animal models, bolstering the compound’s prospects for human translation. Importantly, Benz notes that N-PPG’s unique mitohormetic properties may widen its application beyond rare PH2, potentially preventing the recurrence of common calcium oxalate kidney stones and benefiting other organ systems where mitochondrial robustness is critical.
Given the shared metabolic pathway involving hydroxyproline catabolism in both PH2 and PH3 subtypes, researchers anticipate N-PPG may also offer therapeutic utility for PH3 patients once suitable animal models become accessible. Additional pharmacokinetic and detailed safety profiling studies are planned to expedite clinical development. Parallel chemical optimization efforts aim to delineate the mitohormesis-related kidney benefits of N-PPG from those deriving solely from enzyme inhibition, which could inform the design of future targeted therapies with improved efficacy and safety.
The researchers candidly acknowledge that this venture into nephrology and rare kidney stone disease emerged serendipitously from cross-disciplinary dialogue rather than a premeditated strategy. Ellerby’s focus on orphan neurological diseases and Benz’s oncology background underscore the novelty and breadth of collaborative science fostered at the Buck Institute. This integrative research environment—bringing together diverse expertise and encouraging open scientific exchange—has been instrumental in uncovering innovative treatments with meaningful translational potential.
The collective enthusiasm from the team is palpable, as this initial success heralds hope for patients and families affected by PH2, who have long awaited effective therapies to alleviate the fatal consequences of oxalate nephropathy. Beyond the immediate impact on hyperoxaluria, this discovery opens new avenues to exploit mitohormesis as a therapeutic axis in mitochondrial medicine, broadening the horizon for addressing multiple age-related and metabolic diseases. Consequently, N-PPG could emerge not merely as a rare disease treatment but as a pioneering molecule with far-reaching implications across medicine.
The study, published in the high-impact journal Kidney International, stands as a testament to innovative scientific exploration—merging metabolic biochemistry, mitochondrial biology, and nephrology to tackle one of the most intractable renal disorders. As research moves forward, the medical research community eagerly anticipates clinical trials that could eventually deliver this promising compound to patients, transforming the prognosis of PH2 and perhaps altering the management of kidney stone disease on a global scale.
Subject of Research: Animals
Article Title: N-Propargylglycine Restores Survival by Preventing Calcium Oxalate Stone Formation, Tubular Injury, and Kidney Dysfunction in a Lethal Mouse Model of Primary Hyperoxaluria Type 2
News Publication Date: 20-Mar-2026
Web References: https://pubmed.ncbi.nlm.nih.gov/41866121/; http://dx.doi.org/10.1016/j.kint.2026.02.024
References: DOI: 10.1016/j.kint.2026.02.024
Keywords: Primary Hyperoxaluria Type 2, N-propargylglycine, calcium oxalate kidney stones, hydroxyproline dehydrogenase, mitohormesis, mitochondrial resilience, kidney failure, rare genetic disorder, metabolic disease, nephrology, mitochondrial biology
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