CSL, Alentis Partner on Claudin-1 MAb Lixudebart for Kidney Disease

CSL and Alentis Therapeutics have entered an exclusive global collaboration to co-develop and co-promote lixudebart, a potential first-in-class monoclonal antibody (mAb) targeting claudin-1 for a range of rare kidney, liver, and other diseases, CSL announced October 5, 2026. ¹ Under the agreement, CSL will pay Alentis an initial $355 million, with up to an additional $1.2 billion in commercial milestones. Upon commercialization, the companies will share global profits with 55% to CSL and 45% to Alentis.¹

"This partnership enables us to dramatically accelerate the development of lixudebart in several indications in parallel," said Mark Pruzanski, MD, CEO, Alentis, in a company press release.¹ "We are convinced CSL's demonstrated clinical development and commercialization capabilities in AAV [adeno-associated virus] and kidney diseases makes them the right partner to bring lixudebart to patients."

What is lixudebart, and how does it work?

Lixudebart (formerly ALE.F02) selectively targets exposed claudin-1, a protein that drives inflammatory and fibrotic signaling across the kidney, liver, lung, intestine, and other solid organs.¹ Research from Alentis's founding scientists describing a mAb against nonjunctional claudin-1 found that blocking the protein reduced fibrosis and altered cell plasticity in patient-derived liver and lung tissue models, providing early preclinical support for the claudin-1-targeting approach lixudebart is built on.²

What indications will the companies pursue first?

The lead indication is anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis with rapidly progressive glomerulonephritis (AAV-RPGN), a rare and potentially life-threatening autoimmune disease in which ANCA autoantibodies attack small blood vessels in the kidney, causing rapid loss of kidney function that can progress to irreversible damage and end-stage renal disease despite potent immunosuppressive treatment.¹ Lixudebart is being evaluated in an ongoing phase 2 trial (RENAL) in AAV-RPGN.

CSL and Alentis also plan to develop the mAb for focal segmental glomerulosclerosis (FSGS), a rare progressive kidney disease, and primary sclerosing cholangitis (PSC), an autoimmune chronic liver disease.¹ Claudin-1 has separately been identified as a disease-relevant mediator in PSC itself, providing additional biological rationale for testing lixudebart in that indication.³

What clinical data exist for lixudebart so far?

In an interim analysis of 26 patients with AAV-RPGN in the phase 2 RENAL trial, lixudebart showed improvement in kidney function, measured by estimated glomerular rate and proteinuria, at 24 weeks.¹ In the phase 1b FEGATO trial, which enrolled 41 patients with advanced F3/F4 liver fibrosis, lixudebart was associated with improved liver function at 6 weeks.¹ Both studies showed dose-dependent claudin-1 target engagement along with a favorable safety and tolerability profile, and lixudebart has received FDA orphan drug designation for idiopathic pulmonary fibrosis.¹

What are the terms of the agreement, and why these 2 companies?

CSL will fully fund the ongoing phase 2 RENAL trial, the planned phase 3 AAV-RPGN trial, and the phase 2 FSGS and PSC trials.¹ William Mezzanotte, MD, CSL's executive vice president, head of R&D, and chief medical officer, said in the release, "We believe lixudebart has the potential to become an important new therapeutic option to help improve kidney function and prevent progression to end-stage kidney disease, first in AAV-RPGN and hopefully also in focal segmental glomerulosclerosis, while potentially showing similar benefit on liver function in primary sclerosing cholangitis."¹

What are the limitations?

The phase 2 RENAL interim results are drawn from just 26 patients and have not been peer-reviewed or published in full, and no data from the FSGS or PSC programs have yet been disclosed. CSL and Alentis did not provide a timeline for completing the phase 3 AAV-RPGN trial or for potential regulatory filings, and the $1.2 billion milestone figure represents a maximum potential total contingent on development, regulatory, and commercial targets that may not necessarily be met.

References

1. CSL. CSL and Alentis announce global partnership to develop and commercialize lixidebart for rare kidney and liver diseases. Press release. Published October 5, 2026. Accessed October 6, 2026. https://newsroom.csl.com/2026-10-04-CSL-and-Alentis-announce-global-partnership-to-develop-and-commercialise-lixudebart-for-rare-kidney-and-liver-diseases
2. Roehlen N, Saviano A, El Saghire H, et al. A monoclonal antibody targeting nonjunctional claudin-1 inhibits fibrosis in patient-derived models by modulating cell plasticity. Sci Transl Med. 2022;14(676):eabj4221. doi:10.1126/scitranslmed.abj4221
3. Del Zompo F, Crouchet E, Ostyn T, et al. Claudin-1 is a mediator and therapeutic target in primary sclerosing cholangitis. J Hepatol. 2025;83(6):1305-1319. doi:10.1016/j.jhep.2025.08.005