China’s Linafexor: A Paradigm Shift in Drug Design for Liver Disease
Chinese researchers have developed a groundbreaking new drug that could fundamentally change how we treat chronic liver diseases — and, more importantly, how we think about drug design itself. The drug, Linafexor (CS0159), represents a first-in-class approach to treating bile acid metabolism disorders by mimicking the body’s natural physiological rhythms rather than overriding them, as People’s Daily reported.
Developed by a joint team from the Shanghai Institute of Materia Medica (SIMM) at the Chinese Academy of Sciences, Linafexor is a non-bile acid FXR (Farnesoid X Receptor) pulsed agonist that has completed Phase II clinical validation. The research was published in the journal Nature, and the drug is being commercialized by CASI Pharmaceuticals (凯思凯迪), which recently completed a 318 million RMB (approximately $44 million USD) Series D financing round.
The Problem with “Long-Acting” Drugs
For decades, the pharmaceutical industry has operated on a simple principle: the longer a drug stays in the body, the better. Longer half-lives mean less frequent dosing, better patient compliance, and more sustained therapeutic effect. This logic has driven the development of dozens of FXR agonists over the past 20 years — nearly all designed as “long-acting” agents that essentially hold the receptor switch down continuously.
The problem? The human body doesn’t work that way.
Bile acids, which act as the liver’s “natural detergent” for digesting fats and regulating metabolism, operate on a rhythmic cycle. They surge after meals and recede during fasting. The FXR receptor — the master switch that senses bile acid levels and regulates their synthesis, transport, and clearance — is designed to open and close in response to these natural fluctuations.
“When most new drugs pursue ‘the longer they stay in the body, the better,’ the research team ‘followed the body’s physiological rhythms’ to design this ‘quickly coming and going’ drug Linafexor,” said Li Jia, Director of SIMM, as People’s Daily reported.
A Radical New Approach: Pulsed Activation
Linafexor represents a complete departure from conventional thinking. Instead of sustained activation, it delivers “pulsed activation” — pressing the receptor switch briefly and then letting go, much like a heartbeat or the ebb and flow of tides.
The drug is designed to be “fast-in, fast-out” in the human body. Across multiple species — mice, rats, dogs, and monkeys — Linafexor’s half-life is less than one hour, far shorter than previous long-acting FXR drugs. This means the drug is quickly cleared from the body after doing its work, rather than accumulating over time.
“Health is a dynamic physiological homeostasis; disease is the disruption of this homeostasis. An ideal drug should restore and strengthen normal physiological rhythms, not disrupt them,” Li Jia explained.
This insight, which the team calls “first principles of drug design” from physiological rhythms, could have far-reaching implications. Many physiological processes — hormone signaling, immune regulation, and circadian metabolic rhythms — similarly depend on rhythmic rather than continuous signaling.
Addressing a Massive Unmet Need
The clinical need for better treatments is enormous. Primary Biliary Cholangitis (PBC) affects over 10 million patients globally, and nearly half have inadequate responses to first-line therapy with ursodeoxycholic acid (UDCA). Currently, no domestically developed second-line drug is approved in China.
The existing alternative, obeticholic acid (OCA), has a pruritus (severe itching) side effect rate exceeding 60%, making it poorly tolerated by many patients. Linafexor’s pulsed activation mechanism appears to dramatically reduce these side effects while maintaining efficacy.
Beyond PBC, Linafexor targets multiple bile acid metabolism disorders:
- Primary Sclerosing Cholangitis (PSC) — for which it has received FDA Orphan Drug designation
- Metabolic dysfunction-associated steatohepatitis (MASH) — a massive unmet market with no curative drugs globally
- Homozygous Familial Hypercholesterolemia (HoFH) — a rare genetic disorder
The drug has also received FDA Fast Track qualification, underscoring its potential.
Strong Validation from Clinical Data
Phase II data for Linafexor was presented at the 2026 European Association for the Study of the Liver (EASL) Annual Meeting as a late-breaking oral presentation and was selected as the Annual Best Research Highlight. The data confirmed its efficacy in patients with inadequate response to UDCA, with a favorable safety profile.
Phase III trials are now being prepared simultaneously in China and the United States, positioning Linafexor to potentially become the first domestically developed, globally synchronized second-line innovative drug for PBC.
A Promising Pipeline and Strong Backing
CASI Pharmaceuticals, founded in 2017 by SIMM researcher Xu Huaqiang, has built a robust pipeline around bile acid metabolism. Beyond Linafexor, the company’s portfolio includes CS060380 (a THR-β agonist for MASH in Phase II) and CS060304 (for HoFH, with clinical trial approval).
The company has raised over 1.4 billion RMB (approximately $194 million USD) cumulatively. Its Series D round in June 2026, led by Taiping Fund and Shanghai Science and Technology Innovation Group, followed an early R&D collaboration with Eli Lilly’s ExploR&D announced in April 2026.
“Bile acid metabolism is the most promising frontier in metabolic liver disease, but the barrier to original innovation is extremely high,” said Xu Huaqiang, Founder and Chief Scientist of CASI Pharmaceuticals, as reported by MedValley.
Broader Implications for Drug Discovery
Perhaps the most significant aspect of Linafexor is not the drug itself, but the paradigm it represents. The concept of pulsed activation — designing drugs that work with the body’s natural rhythms rather than against them — could be applied across therapeutic areas.
This approach may help address two of the most persistent challenges in drug development: toxicity and narrow therapeutic windows. By avoiding continuous receptor activation, pulsed agonists may reduce the desensitization and side effects that have plagued many drug candidates.
As Li Jia put it: “An ideal drug should restore and strengthen normal physiological rhythms, not disrupt them.”
What to Watch For
As Linafexor moves into Phase III trials, several key questions will determine its ultimate impact:
- Efficacy at scale: Will the promising Phase II results hold in larger, more diverse patient populations?
- Regulatory pathway: Can CASI Pharmaceuticals navigate simultaneous approvals in China and the US?
- Commercial adoption: Will Linafexor’s tolerability advantage be sufficient to displace existing therapies?
If successful, Linafexor could not only provide a much-needed treatment option for millions of liver disease patients but also validate a new philosophy of drug design — one that respects the rhythm of life itself.
The SIMM press release notes that the Nature publication details the structural basis and preclinical validation of this novel approach, providing a foundation for future pulsed agonist development across multiple therapeutic areas.
This article is based on reporting from People’s Daily, the Shanghai Institute of Materia Medica, and MedValley, with additional context from CASI Pharmaceuticals disclosures.