New U.S. Registry Study Adds Tavneos Liver Injury Evidence for Claim Reviews

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Last reviewed: September 25, 2026

A new U.S. registry study gives
Tavneos families a more concrete
piece of the puzzle: what happened
to 238 American patients who
received avacopan for
ANCA-associated vasculitis in
routine rheumatology care. The
answer is not simple. Most patients
in the study did not have major
liver test problems, but two
patients developed drug-induced
liver injury that the researchers
rated as highly probable for
avacopan causation. One was severe.

That mix matters for a legal
review. It means nobody should
assume every abnormal liver test
after Tavneos is automatically a
claim. It also means serious liver
injury in a U.S. Tavneos patient
cannot be brushed aside as a purely
foreign safety signal.

For the bigger picture, start with our Tavneos lawsuit hub. If you are looking across drug and device investigations, our current mass tort docket shows the matters we are tracking.

What the U.S. registry study actually adds

The report, published in Arthritis
& Rheumatology and indexed by
PubMed, used the Rheumatology
Informatics System for
Effectiveness registry. Researchers
looked for ANCA-associated
vasculitis patients with at least
one avacopan prescription from
October 2021 through March 2025.

Then they looked at liver labs. The
study used FDA-style thresholds,
including AST or ALT above three
times the upper limit of normal,
alkaline phosphatase above two
times the upper limit of normal, or
total bilirubin above 2 mg/dL.

The numbers were small, but they
were not zero:

238 patients had been treated with avacopan.
Five had elevated AST.
Three had elevated ALT.
Four had elevated alkaline phosphatase.
Two had elevated bilirubin.
Two patients, or 0.8% of the group, were identified as drug-induced liver injury cases.

Both DILI cases landed in the RUCAM
highly probable range. In plain
English, that points strongly toward
the drug as the cause. One case also
had biopsy-confirmed severe
hepatocellular injury.

For families, the takeaway is
narrow: the study supports a
careful records review when Tavneos
use is followed by serious liver
injury. It does not replace that
review.

How this fits with the FDA warning

FDA's March 31, 2026 Drug Safety
Communication came from a different
type of evidence. The agency
reviewed postmarketing data,
literature, and adverse-event
reporting and identified 76
drug-induced liver injury cases
with reasonable evidence of a
causal association with avacopan.

Those FDA cases included 54
hospitalizations and 8 deaths. FDA
also described seven
biopsy-confirmed vanishing bile
duct syndrome cases. All seven
involved hospitalization, and three
had a fatal outcome.

The registry study answers a
different question. It looks at a
defined U.S. patient group instead
of reports sent to regulators. That
is useful because it puts the lab
timeline, the prescribing record,
and the diagnosis record in the
same lane.

The records we would want first

Families rarely have a perfect file
on day one. That is fine. The first
job is to build a timeline that a
doctor, lawyer, or expert can
actually follow.

Useful records may include:

The first Tavneos or avacopan prescription date.
Pharmacy fill records, including refills and stop dates.
Rheumatology notes explaining why Tavneos was started.
Baseline ALT, AST, alkaline phosphatase, bilirubin, and INR if available.
Follow-up liver panels during the first three months.
Later liver panels if treatment continued.
Notes about itching, jaundice, dark urine, light-colored stools, nausea, unusual fatigue, abdominal swelling, or right upper abdominal pain.
Emergency room, hospital, hepatology, biopsy, transplant evaluation, transplant, or death records.
A medication list from the same window, including antibiotics, antifungals, immune medicines, supplements, and over-the-counter drugs.
Any FDA MedWatch report confirmation.

A claim review may focus first on
serious outcomes: drug-induced
liver injury requiring
hospitalization, vanishing bile
duct syndrome, acute liver failure,
transplant evaluation, liver
transplant, or death after Tavneos
exposure.

Mass Tort America reviews potential Tavneos claims involving those injuries. You can also read about how Baker Legal Team reviews claims before submitting information.

Why the first months matter

FDA told clinicians to run liver
panel testing every two weeks in
the first month, monthly for the
next five months, and then as
clinically indicated. FDA also
advised prompt discontinuation and
evaluation when certain liver tests
rise above specified thresholds, or
when a patient has symptoms of
cholestasis such as jaundice or
pruritus.

The registry study points the same
way. The authors said liver enzyme
elevations were infrequent in the
U.S. cohort, but severe
drug-induced liver injury occurred.
They said the findings support
vigilant early monitoring and
informed risk discussions while
regulators continue reassessing
Tavneos.

For a legal screening, missed
testing can matter. So can the
exact date a symptom first
appeared, the date Tavneos was
stopped, and whether liver labs
improved after discontinuation.

Regulatory action is evidence, not a shortcut

CDER proposed withdrawing Tavneos
approval on April 27, 2026. The
agency said new information
indicated Tavneos had not been
shown to be effective for its
approved use and that the
application contained untrue
statements of material fact. The
Federal Register notice tied those
concerns to the ADVOCATE study data
and also discussed serious
hepatotoxicity concerns.

European regulators have already
gone further. EMA's Tavneos
referral page says the European
Commission issued a final legally
binding decision on August 4, 2026
revoking Tavneos marketing
authorization in EU Member States.

Those actions are important. They
are not a settlement, a court
finding, or proof that Tavneos
caused one person's injury. An
individual case still depends on
timing, diagnosis, medical records,
competing causes, and state filing
deadlines.

FAQ

Did the U.S. registry study find Tavneos liver injury in American patients?

Yes. It identified two drug-induced
liver injury cases among 238
avacopan-treated patients. Both
were rated highly probable for
avacopan causality.

Does a normal early liver panel rule out a Tavneos claim?

No. A reviewer usually needs the
full timeline: later labs,
symptoms, hospitalization records,
biopsy findings, other medicines,
and when Tavneos was stopped.

Should patients stop Tavneos because of this study?

No one should stop or change a
prescribed vasculitis medication
without medical advice. Patients
with possible liver injury symptoms
should contact their healthcare
professional promptly.

Sources

Informational and attorney advertising disclaimer

This article is for general
information and attorney
advertising. It is not medical
advice and does not create an
attorney-client relationship. Prior
results do not guarantee a similar
outcome. If you are currently
taking Tavneos, talk with your
prescribing doctor before making
any medication changes.

Robert B. Baker, Board-Certified Civil Trial Attorney

Claims reviewed by Baker Legal Team
Robert B. Baker, Esq., B.C.S. — Board-Certified Civil Trial Lawyer. 30+ years of trial experience, more than $400 million recovered for clients. About Robert Baker →