CSL Limited (ASX:CSL) has entered an exclusive global collaboration with Alentis Therapeutics to co-develop and co-promote lixudebart, an investigational monoclonal antibody targeting claudin-1.

The agreement, announced on 5 October 2026, covers development across several rare kidney and liver diseases and places CSL in charge of funding the remaining specified clinical development program.

Partnership Terms

Under the agreement, CSL will make an initial payment of US$355 million to Alentis.

Alentis may also receive up to US$1.2 billion in additional commercial milestone payments if specified development and commercial objectives are reached.

Those milestone payments are contingent and are not guaranteed.

If lixudebart reaches commercialisation, global profits will be shared 55% to CSL and 45% to Alentis.

CSL will fully fund completion of the ongoing Phase 2 RENAL trial, the planned Phase 3 trial in ANCA-associated vasculitis with rapidly progressive glomerulonephritis, Phase 2 trials in focal segmental glomerulosclerosis and primary sclerosing cholangitis, and related development activities.

Lixudebart Targets Claudin-1

Lixudebart, previously known as ALE.F02, is an investigational monoclonal antibody that selectively targets exposed claudin-1.

Claudin-1 is associated with inflammatory and fibrotic signalling pathways across several organs, including the kidneys, liver and lungs.

The lead clinical program is focused on ANCA-associated vasculitis with rapidly progressive glomerulonephritis, a rare autoimmune disease that can cause rapid deterioration in kidney function.

Phase 2 RENAL Trial

Lixudebart is currently being assessed in the Phase 2 RENAL trial in patients with ANCA-associated vasculitis and rapidly progressive glomerulonephritis.

CSL and Alentis reported an interim analysis involving 26 patients.

The companies said the analysis showed improvements in kidney function at 24 weeks, assessed through estimated glomerular filtration rate and proteinuria.

The data are interim results from a relatively small patient group and do not represent a completed pivotal study.

A Phase 3 trial in the same indication is planned.

Additional Kidney and Liver Indications

The collaboration also covers focal segmental glomerulosclerosis and primary sclerosing cholangitis.

Focal segmental glomerulosclerosis is a kidney disease involving scarring of the kidney’s filtering structures.

Primary sclerosing cholangitis is a chronic liver disease affecting the bile ducts.

Both indications are planned for Phase 2 development under the collaboration.

The agreement therefore gives CSL exposure to several clinical programs built around the same antibody and biological target.

Liver Fibrosis Data

Lixudebart has also been studied in the Phase 1b FEGATO trial.

That study involved 41 patients with advanced F3 or F4 liver fibrosis.

The companies reported improved liver function at six weeks.

As with the RENAL interim findings, these results are early-stage clinical data and require further investigation in larger studies before any regulatory conclusion can be reached.

FDA Orphan Drug Designation

Lixudebart has received Orphan Drug designation from the US Food and Drug Administration for idiopathic pulmonary fibrosis.

An Orphan Drug designation does not represent Marketing approval.

It is a regulatory designation for therapies being developed for rare diseases and can provide certain development incentives.

The current CSL collaboration is focused on kidney and liver indications rather than commercialisation in idiopathic pulmonary fibrosis.

Alentis Pipeline Continues Separately

Alentis is a clinical-stage biotechnology company developing claudin-1-targeting antibodies and antibody-drug conjugates.

Beyond lixudebart, its pipeline includes ALE.P02 and ALE.P03.

ALE.P02 has received FDA Fast Track Designation for advanced or metastatic claudin-1-expressing squamous cancers and is being assessed in Phase 1/2 studies.

ALE.P03 is also in Phase 1/2 development.

These oncology programs are separate from the CSL collaboration covering lixudebart.

Development Risk Remains

Lixudebart remains an investigational therapy and has not received regulatory approval for the indications covered by the collaboration.

The current clinical evidence includes an interim Phase 2 analysis and an earlier Phase 1b study.

Further development will require completion of the RENAL trial, initiation and completion of the planned Phase 3 study, and progression of the additional Phase 2 programs.

Clinical studies can be delayed, modified or discontinued depending on safety, efficacy, recruitment and regulatory factors.

The US$355 million upfront payment is committed under the agreement, while the additional US$1.2 billion in milestone payments depends on future commercial progress.

Next Clinical Milestones

The immediate development priorities are completion of the Phase 2 RENAL trial and preparation for the planned Phase 3 study in ANCA-associated vasculitis with rapidly progressive glomerulonephritis.

Phase 2 studies in focal segmental glomerulosclerosis and primary sclerosing cholangitis are also planned.

Future disclosures are expected to provide further information on trial timing, patient recruitment, clinical outcomes and the accounting treatment of the upfront payment.