Rectify's RTY-406: A New Dawn for Devastating Liver Disease?

BARCELONA, Spain – May 27, 2026 – In the global search for a treatment for Primary Sclerosing Cholangitis (PSC), a relentless and progressive liver disease, hope often feels as rare as the condition itself. Today, at the prestigious European Association for the Study of the Liver (EASL) Congress 2026, Boston-based Rectify Pharmaceuticals presented new data that may signal a pivotal shift in this challenging landscape. The company unveiled compelling preclinical results for its drug candidate, RTY-406, suggesting a potential first-in-class therapy that tackles the disease at its biological roots.

The data, derived from studies in both mouse models and non-human primates, demonstrated that RTY-406 significantly improved multiple markers of disease. This has bolstered the company's confidence as it advances the oral small molecule into Phase 1 human clinical trials, offering a tangible glimmer of hope for a patient community that has waited decades for a breakthrough.

A Disease of Desperate Unmet Need

To understand the significance of Rectify's announcement, one must first grasp the grim reality of Primary Sclerosing Cholangitis. PSC is a chronic disease where the immune system appears to mistakenly attack the bile ducts, causing inflammation and scarring (fibrosis). Over time, these ducts narrow and harden, leading to a dangerous backup of bile in the liver—a condition known as cholestasis. This process triggers a cascade of damage, culminating in cirrhosis, liver failure, and a significantly increased risk of bile duct cancer.

With a prevalence as low as 1 in 100,000 people, the disease is rare, but its impact is severe. The median survival from diagnosis without intervention is around 15 years. Currently, there are no approved therapies that can halt or reverse the progression of PSC. Patients are managed with treatments aimed at alleviating symptoms like debilitating fatigue and intense itching, or procedures to temporarily open blocked ducts. For those with end-stage disease, the only curative option is a liver transplant—a major surgery with its own risks and the potential for the disease to recur even in the new organ.

This stark therapeutic void has made PSC a critical area of focus for researchers and pharmaceutical companies. The search is not just for a better treatment, but for the first treatment that can fundamentally alter the disease's course.

Fixing the Cellular Machinery

Rectify Pharmaceuticals is approaching this challenge with a novel class of drugs called Positive Functional Modulators (PFMs). Unlike therapies that aim to manage downstream symptoms, PFMs are designed to directly restore the function of specific proteins that are not working correctly. This approach has seen remarkable success in other fields, most notably with CFTR modulators that have transformed the treatment of cystic fibrosis.

RTY-406 is a dual-acting PFM that targets two critical proteins essential for healthy bile flow: ABCB4 and BSEP. These proteins act as cellular pumps on the surface of liver cells. ABCB4 is responsible for secreting phospholipids into the bile, which protect the bile ducts from the harsh, detergent-like effects of bile acids. BSEP is the primary pump for exporting those bile acids out of the liver cells and into the ducts. In PSC, the function of these pumps is believed to be impaired, leading to toxic bile composition and reduced bile flow—the core drivers of the disease.

"Primary sclerosing cholangitis is a devastating disease for which there are no approved therapies that address the underlying biology driving disease progression," said Rajesh Devraj, PhD, President and Chief Executive Officer of Rectify Pharmaceuticals, in a statement. "RTY-406 simultaneously enhances the function of ABCB4 and BSEP, directly targeting two core pathophysiological drivers of PSC: abnormal bile composition and impaired bile flow."

Compelling Data from Preclinical Studies

The optimism surrounding RTY-406 is fueled by the robust data presented at EASL. In a mouse model designed to mimic PSC, treatment with RTY-406 led to a cascade of positive effects. The drug reduced levels of serum bile acids and alkaline phosphatase (ALP), key blood markers that indicate liver stress and bile duct injury. It also decreased the expression of genes associated with inflammation, ductular reaction (a marker of cholangiocyte injury), and fibrosis—the dangerous scarring that leads to cirrhosis.

Crucially, Rectify also presented data showing the drug's mechanism works as intended in non-human primates, a critical step in translating animal research to human potential. In healthy primates, daily oral administration of RTY-406 led to dose-dependent reductions in ALP and gamma-glutamyl transferase (GGT), another key indicator of bile duct health. These results provide strong evidence that RTY-406 is successfully engaging its targets and improving bile flow and composition in a species much closer to humans.

"What is encouraging about these results is the consistency of the findings across both disease models and non-human primates," added Pol Boudes, MD, Rectify’s Chief Medical Officer. "We observed evidence that RTY-406 improves bile composition and bile flow while reducing markers associated with liver and bile duct injury, all without evidence of liver toxicity."

Charting a New Course in a Crowded Field

Rectify is not alone in the race to conquer PSC. The competitive landscape includes several companies exploring different therapeutic avenues, from modulating bile acid receptors (FXR agonists) and limiting bile acid reabsorption (IBAT inhibitors) to targeting inflammation and fibrosis directly. However, this field has been fraught with challenges, with several promising candidates failing in late-stage trials over the years.

RTY-406's unique dual-modulator mechanism, which aims to restore the natural physiological process of bile formation, could be a key differentiator. By addressing the problem at its source rather than mitigating the consequences, it represents a fundamentally different strategy. The company's belief that RTY-406 has "pipeline-in-a-pill" potential suggests that if successful in PSC, its mechanism could also prove beneficial in a range of other cholestatic liver diseases.

With RTY-406 now entering Phase 1 clinical trials, the focus will shift from animal models to human subjects. The journey from the lab to the pharmacy is long and uncertain, but for the thousands of patients living with PSC, the data presented in Barcelona represents a significant and welcome step forward. The upcoming trials will be watched closely by patients, physicians, and researchers alike, all hoping that this promising science translates into a long-awaited therapy.