USC researcher Eunji Chung spent over a decade learning to steer nanoparticles through the body. Now she’s using that knowledge to take on one of the most common inherited kidney disorders.

Eunji Chung and her team were working hard to engineer and design tiny drug-carrying particles, called nanoparticles, to deliver medicine to the heart. When the results came back, the specific particles they had developed  had another target in mind: They had traveled to the kidneys, where they gathered in the tissue with unexpected precision. It was not what anyone had planned. It was also too striking to dismiss.

“For a moment, we thought we had failed,” said Chung, the Dr. Karl Jacob Jr. and Karl Jacob III Early Career Chair and an associate professor of biomedical engineering, chemical engineering, medicine and surgery at the Alfred E. Mann Department of Biomedical Engineering at USC Viterbi. “But then we realized the particles were doing something very specific.”

Rather than discarding the result, Chung’s lab began to investigate it.

That fortuitous discovery now anchors Silver Spur Therapeutics, the Los Angeles-based startup Chung founded in 2024. The company is working to develop a new class of nanoparticle treatments for autosomal dominant polycystic kidney disease, or ADPKD, an inherited condition in which cysts slowly overtake the kidneys and eventually destroy their ability to function.

From discovery to startup

Chung didn’t set out to become an entrepreneur. “I thought strong science would find its way,” she said.

Promising research often stalls in university labs — not because the science isn’t there, but because moving a discovery forward requires things academia rarely has: manufacturing capacity, regulatory expertise and the infrastructure to run large-scale human clinical trials.

“There is a gap between discovery and the clinic,” she said.

Silver Spur Therapeutics aims to bridge the two. The company has secured early funding for preclinical development, brought on experienced leadership, including a CEO, and moved a bit closer to commercialization after spending time in the USC and Techstars Accelerator.

A disease with few options

ADPKD affects roughly 1 in 400 to 1 in 1,000 people worldwide, making it one of the most common inherited kidney disorders. In people with the condition, fluid-filled cysts form and slowly expand throughout the kidneys over years or decades, crowding out healthy tissue and eroding the organ’s ability to filter waste from the blood.

The disease often moves silently. By the time many patients are diagnosed, significant damage has already occurred. Many eventually need dialysis, in which a machine takes over the kidneys’ filtering role, or a kidney transplant.

Treatment options remain limited. The only FDA-approved therapy can slow disease progression over time, but many patients find its side effects unmanageable, among them liver-related complications and a severe, persistent thirst. In time, many people stop taking the drug.

“When you look at the patient experience, it is clear there is still a major unmet need,” Chung said.

Reaching the right cells

Chung’s team is developing therapies using a molecule called small interfering RNA, or siRNA. Think of it as a biological off switch: it can be programmed to seek out and silence specific genes, in this case, the ones responsible for triggering cyst growth.

The challenge is getting that molecule to the right place. RNA is fragile: It breaks down quickly in the bloodstream if left unprotected. And a drug that spreads throughout the body loses potency while raising the risk of harming organs that don’t need treatment.

“If a drug goes everywhere, you lose effectiveness and increase the risk of side effects,” Chung said. “You need it to go where the disease is.”

Her lab’s answer is a custom nanoparticle, a microscopic capsule that carries the siRNA, protects it as it travels through the bloodstream, and unloads only once it reaches the kidney, releasing the siRNA inside cells where it can silence the genes driving cyst growth.

“I often explain it as an Amazon package,” she said. “You need both protection and the correct address.”

Most nanoparticle-based drug delivery systems end up in the liver or spleen, which naturally clear particles out of the blood. Engineering particles that bypass those organs and home in on the kidney instead requires precise control over how they are built. Chung’s lab has spent more than a decade developing exactly that understanding.

Helping people

Chung’s research centers on understanding how a nanoparticle’s physical properties, its size, shape and surface chemistry, determine where it goes once it enters the body. By mapping those relationships systematically, her lab has moved beyond trial and error, gaining the ability to design particles with a specific biological destination in mind. That knowledge is what made the kidney-targeting discovery possible, and what Silver Spur is now trying to translate into an effective medicine.

Her work has earned Chung myriad plaudits, including election as a fellow of both the American Institute for Medical and Biological Engineering, the Biomedical Engineering Society, and the American Heart Association. Technologies she helped develop in graduate school at Northwestern University also made it into clinical use, a reflection of her emphasis on moving research out of the lab and into practice.

That same drive now shapes Silver Spur’s mission. The company is focused on advancing its ADPKD program while building a broader pipeline of kidney-targeted therapies.

“For me, the goal has never been just to publish,” Chung said. “It’s to take something from the lab and actually help people by seeing it reach patients.”