Name: Atebrioz (zilurgisertib) in Fibrodysplasia ossificans progressiva: Contraindications/Warnings/Precautions/Adverse effects
Published: 2026-09-27T12:28:00-04:00

Contraindication: pregnancy

“ATEBRIOZ is contraindicated in pregnancy. ATEBRIOZ can cause fetal harm when administered to a pregnant woman” (opens the prescribing information at this quote)

Embryo-fetal toxicity

“Based on its mechanism of action and findings from animal reproduction studies, ATEBRIOZ can cause fetal harm when administered to a pregnant woman. Oral administration of zilurgisertib to pregnant rats during the period of organogenesis resulted in adverse outcomes, including embryofetal lethality, decreased fetal weight, and skeletal malformations at exposures ≥ 3-times the human exposure at the clinical dose of 100 mg” (opens the prescribing information at this quote)
“For females of reproductive potential, verify that the patient is not pregnant prior to initiation of treatment. Advise females of reproductive potential to use effective contraception during treatment with ATEBRIOZ and for one week after the final dose. Advise patients to discontinue ATEBRIOZ immediately if pregnancy occurs during treatment and to contact their healthcare provider” (opens the prescribing information at this quote)

Adverse reactions occurring in 10% or more of participants through Week 24

“The safety of ATEBRIOZ was evaluated in a 24-week, multicenter, randomized, double-blind, placebo-controlled trial (Study 1; NCT05090891). Sixty-three patients (28 adults and 35 pediatric patients 12 years of age and older) with FOP were randomized to ATEBRIOZ 100 mg (n = 32) or placebo (n = 31) once daily for 24 weeks.” (opens the prescribing information at this quote)

Adverse reaction	Atebrioz (N = 32), n (%)	Placebo (N = 31), n (%)
Headache	“7 (22)”	“5 (16)”
Arthralgia	“7 (22)”	“3 (10)”
Upper respiratory tract infection	“7 (22)”	“3 (10)”
Epistaxis	“4 (13)”	“0”
Nausea	“4 (13)”	“1 (3)”

Adverse reactions occurring in fewer than 10% of participants

“In patients receiving ATEBRIOZ 100 mg orally once daily through Week 24, adverse reactions occurring in < 10% of patients included gastroenteritis, gastroesophageal reflux disease, iron deficiency anemia, rash (3 patients each), and alopecia (2 patients). None of these events were reported in the placebo group.” (opens the prescribing information at this quote)

Laboratory findings: serum iron, hemoglobin, and transferrin saturation

“No significant differences in mean ferritin change from baseline was observed between ATEBRIOZ- and placebo-treated patients, including patients who took iron supplements. Based on the data through Week 100, the increases in serum iron and transferrin saturation with ATEBRIOZ were not associated with signs or symptoms of iron overload.” (opens the prescribing information at this quote)

Nonclinical hepatic findings and carcinogenic potential

“Long-term carcinogenicity studies have not been conducted with zilurgisertib. In a 6-month repeat-dose toxicity study, rats orally administered zilurgisertib developed dose-dependent basophilic foci of cellular alterations (potential preneoplastic findings) and hepatic iron accumulation in the liver (at exposures comparable to clinical exposure).” (opens the prescribing information at this quote)
“Chronic hepatic iron overload has been associated with hepatocarcinogenesis in animal models and in certain human disease states. The clinical relevance of these findings, including the potential carcinogenic risk in humans treated with zilurgisertib, is uncertain.” (opens the prescribing information at this quote)

Mutagenicity and fertility

“Zilurgisertib is not mutagenic based on the results of a bacterial mutagenicity assay. Zilurgisertib was not clastogenic in either an in vivo micronucleus assay or a comet assay in rats, and no genotoxic effects were observed in a 28-day oral toxicity study in rats.” (opens the prescribing information at this quote)
“Zilurgisertib had no effect on fertility or reproductive function in either male or female rats at doses up to 60 mg/kg/day and 200 mg/kg/day, respectively” (opens the prescribing information at this quote)

Adverse events in healthy participants in the phase 1 studies

“In total, TEAEs were reported for 28 participants (31%) during the SAD study [zilurgisertib, n = 23 (33%); placebo, n = 5 (24%)] and 32 participants (41%) during the MAD study [zilurgisertib, n = 27 (46%); placebo, n = 5 (25%)]” (opens the source at this quote in a new tab)
“No dose-limiting toxicities were observed and no deaths occurred during either study.” (opens the source at this quote in a new tab)
“Two participants withdrew from the MAD study due to TEAEs (tachycardia, n = 1; hypersensitivity, n = 1).” (opens the source at this quote in a new tab)