A new biotech company is tackling one of the world’s most common—and stubborn—genetic kidney diseases, with a bold plan to address the biology at its core.
Renasant Bio, founded with $54.5 million in seed funding, is emerging from the shadows to pioneer next-generation small molecule therapies for autosomal dominant polycystic kidney disease (ADPKD). The financing round, led by 5AM Ventures, also drew support from Atlas Venture, OrbiMed, and Qiming Venture Partners USA, signaling strong investor conviction in the company’s mission to deliver the first truly disease-modifying treatments for ADPKD. Impacting over 12 million individuals worldwide, ADPKD is a dominantly inherited genetic disease in which patients develop cysts in their kidneys that progressively increase in number and size, impairing renal function. These patients end up in renal failure, and, because there’s currently only one approved therapy, Tolvaptan, which isn’t well tolerated, most of these patients require either dialysis or a kidney transplant.
For CEO Emily Conley, PhD, and her team, the solution lies not in symptom management but in fixing the fundamental cellular defects caused by the disease—an approach reminiscent of the therapeutic revolution in cystic fibrosis (CF), another genetic disorder of ion channel dysfunction. Renasant Bio aims to adapt the “corrector and potentiator” strategy that transformed CF care to ADPKD, offering a radically new way to stop, and potentially reverse disease progression. While CF affects roughly 40,000 patients in the U.S., ADPKD affects at least 300,000 in the U.S. and Europe alone—nearly 10 times more. Yet it has no disease-modifying therapies. “CF is a $10 billion market with only a fraction of the patients,” Conley told Inside Precision Medicine. “ADPKD has an even larger population and far greater unmet needs. The therapeutic opportunity is enormous!”
Polycystin science
Even seasoned drug developers have long viewed targeting the root biology of ADPKD as too ambitious. ADPKD is caused by mutations in either the PKD1 or PKD2 genes, disrupting the function of the polycystin-1 (PC1) and polycystin-2 (PC2) proteins, respectively, and preventing the proper formation and function of the calcium-permeable polycystin ion channel. The polycystin complex is massive, a tetramer—one PC1 and three PC2 proteins—which adds yet another layer of complexity. “No single mutation is found in more than 2% of patients,” said Conley. “That makes gene editing impractical. You’d need a separate gene therapy for every tiny patient subpopulation.”
To make things even more complicated, the polycystin channel is located in the single primary cilium of each kidney cell. This microscopic signaling hub regulates various cellular processes, including those that prevent cyst formation. When the polycystin channel doesn’t function properly, renal cysts begin to form and grow, ultimately enlarging the kidneys and destroying their architecture. “The channel resides in the primary cilia—this tiny organelle that’s only one ten-thousandth the size of the cell,” said Conley. “Studying it is incredibly difficult. But we now have the tools and expertise to finally do it.”
Those tools stem largely from the research of UCSF professors Markus Delling, PhD, and Jeremy Reiter, MD, PhD, who first approached 5AM Ventures with the idea of adapting CF therapies to ADPKD. Delling is the only scientist to have ever recorded activity from the polycystin complex in a human cell line—a technical feat that underpins Renasant’s entire platform. “Markus and Jeremy came to 5AM Ventures and said, ‘The technology is finally good enough to go after this ion channel.’ 5AM said yes and wrote the founding check,” said Conley. “A year later, I joined to build the company.”
Page from the CF playbook
To understand Renasant Bio’s approach, it helps to revisit CF. In that disease, mutations in the CFTR ion channel result in either misfolding (so the protein never reaches the cell surface) or dysfunction (the channel remains closed). Drug developers solved this by creating “correctors,” which help stabilize and traffic the protein to the membrane, and “potentiators,” which keep the channel open. Renasant is applying the same two-pronged strategy to polycystins in ADPKD.
Renasant is betting on broad-spectrum small molecules that can correct or potentiate a wide range of mutations. Early preclinical data, Conley says, is promising. “We’ve seen activity across a wide swath of mutations. That gives us confidence that this isn’t just a theoretical idea—it’s translatable,” Conley said.
“PC1 is a huge protein—4,303 amino acids. Most pathogenic mutations cause it to misfold, which triggers ERAD (endoplasmic reticulum associated degradation) quality control mechanisms in the cell to destroy it before it can reach the cilium,” Conley explained. “Our correctors act like chemical chaperones. They stabilize the protein so it escapes the cellular trash bin and gets to where it needs to go.”
But getting the protein to the cilium is only part of the battle. In some cases, the channel is present but still closed. That’s where potentiators come in. Conley said, “In CF, it took a combination of correctors and potentiators—Vertex’s Trikafta is three drugs together [elexacaftor/tezacaftor/ivacaftor]—to deliver meaningful clinical benefits. We think the same is true here. We have two programs: the corrector is in lead optimization, and the potentiator is in discovery.”
All the eggs in one basket
Unlike other biotech startups that spread their bets across multiple indications, Renasant Bio is laser-focused on ADPKD. “This disease is hard,” Conley acknowledged. “There are other related channelopathies, and they’re intriguing, but this is an all-hands-on-deck problem. To do it right, we have to go all in.”
The decision to focus exclusively on ADPKD also reflects the company’s scientific lineage. Conley has assembled a board and leadership team deeply steeped in renal disease, protein trafficking, and small molecule drug discovery. Their Scientific Advisory Board includes the researchers who cloned the PKD1 and PKD2 genes, developed key animal models, and led every major clinical trial in the space—from Tolvaptan to the recent Regulus and Vertex programs. “We’re fortunate to have Nira Dahl on our SAB,” said Conley. “She’s been a lead investigator on all the big trials and is closely connected to Metera, which does genetic testing for patients. We’re also proud that five out of seven members of our board are women—a rarity in biotech.”
While the company is still preclinical, the funding will support progression of the corrector program toward a development candidate while accelerating discovery efforts in the potentiator space. Animal models play a central role in Renasant’s pipeline, and recent advances have allowed for better replication of human disease. “Back when I did my PhD, these models weren’t nearly as predictive,” Conley noted. “Now, they give us critical insight.” Computational modeling is also part of the workflow, though not in the way many might expect. “We’re not using AI to decide where to go—we’re using it after we’ve found interesting molecules to understand how and why they work.”
Renal medicine renaissance?
While other players are entering the ADPKD race—most notably Vertex and Novartis-acquired Regulus—Renasant believes its approach can potentially treat a larger swath of the patient population. Vertex, for example, has stated that their candidate targets about 10% of genetically defined ADPKD patients. Renasant Bio’s aim is broader. Conley said, “We want a therapy that can be effective regardless of which mutation a patient has. That’s the holy grail here. We’re not there yet, but we’re building towards it.”
If Renasant succeeds, it could do for ADPKD what Vertex did with Trikafta for CF—redefine treatment from palliative care to genuine disease modification. But unlike CF, where a few common mutations account for most cases, ADPKD’s mutational spectrum is vast and fragmented. That makes the challenge harder—and the potential reward even greater. “It’s not just a technical challenge—it’s a biological one,” Conley said. “We’re going after the real disease drivers, in a part of the cell that people have long ignored because it’s so hard to study. But the science is ready, the tools are here, and we’re ready.”
For the millions of people living with ADPKD, hope has long been deferred. With Renasant Bio’s launch, that hope may finally find a clear molecular target—and a company bold enough to chase it.
