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Do You Qualify?
Eligibility Checklist
- Received one or more Tepezza (teprotumumab) infusions for thyroid eye disease
- Experienced hearing loss, tinnitus, autophony, or other hearing changes during or after treatment
- Hearing changes are documented by audiogram or medical records (helpful but not required to begin evaluation)
- Claim falls within the applicable statute of limitations in your state
- Willing to provide medical records and participate in the legal process
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Tepezza Hearing Loss Lawsuit
How Tepezza Causes Hearing Loss and Tinnitus
In Plain Language
Tepezza (teprotumumab-trbw) is a monoclonal antibody approved in January 2020 for thyroid eye disease (TED). It works by blocking the insulin-like growth factor 1 receptor (IGF-1R), which plays a central role in the inflammatory orbital tissue expansion that characterizes TED. However, IGF-1R is also critically expressed in the inner ear — specifically in cochlear hair cells, the stria vascularis, and the spiral ganglion neurons that transmit auditory signals to the brain. By inhibiting IGF-1R throughout the body, Tepezza disrupts the maintenance and survival signaling these inner ear structures depend on, leading to sensorineural hearing loss, tinnitus, and autophony (hearing one's own voice or body sounds abnormally loudly). Clinical trial data showed hearing adverse events in approximately 10% of Tepezza patients compared to 0% in the placebo group — a signal that was inadequately disclosed in the original labeling. Post-market studies have since reported hearing changes in up to 65% of patients receiving the standard eight-infusion course.
IGF-1R Inhibition in Cochlear Hair Cells
The inner ear's outer hair cells — responsible for amplifying sound vibrations and enabling frequency discrimination — express high levels of IGF-1R. These cells rely on IGF-1 signaling for survival, metabolic support, and resistance to oxidative stress. When teprotumumab blocks IGF-1R systemically, cochlear hair cells lose this protective signaling. Unlike most cells in the body, cochlear hair cells in humans do not regenerate. Once damaged or lost, the hearing deficit is permanent. This mechanism explains why Tepezza-induced hearing loss is predominantly sensorineural (nerve-based) rather than conductive, and why it can persist long after the drug is discontinued.
Disruption of the Stria Vascularis and Endocochlear Potential
The stria vascularis is a highly vascularized tissue in the cochlea that generates the endocochlear potential — the electrochemical gradient essential for sound transduction. IGF-1R signaling is critical for maintaining the ion transport channels and cellular integrity of the stria vascularis. Tepezza's systemic IGF-1R blockade impairs strial function, reducing the endocochlear potential and diminishing the cochlea's ability to convert mechanical sound waves into electrical nerve impulses. This disruption manifests as a broad decline in hearing sensitivity across multiple frequencies and contributes to the tinnitus reported by many patients.
Spiral Ganglion Neuron Degeneration
Spiral ganglion neurons are the primary afferent neurons that carry auditory information from the cochlea to the brainstem. These neurons depend on neurotrophic support mediated in part through the IGF-1/IGF-1R signaling axis. Animal models have demonstrated that IGF-1 deficiency leads to progressive spiral ganglion neuron loss, reduced auditory nerve conduction, and elevated hearing thresholds. Tepezza's blockade of this pathway in humans is consistent with the pattern of progressive sensorineural hearing decline observed in treated patients, particularly those receiving the full eight-infusion protocol.
Eustachian Tube Dysfunction and Autophony
A distinctive feature of Tepezza-related otologic complaints is autophony — a condition in which patients hear their own voice, breathing, or heartbeat at abnormally high volume. This symptom is associated with eustachian tube dysfunction and patulous eustachian tube, both of which have been reported in Tepezza patients. The mechanism likely involves IGF-1R-mediated changes in the mucosal and cartilaginous tissues of the eustachian tube, leading to abnormal tube patency. While autophony is not hearing loss per se, it is a debilitating auditory disturbance that significantly impairs quality of life and is characteristic of Tepezza ototoxicity.
Danger Factors
- No Regeneration of Human Cochlear Hair Cells: Unlike birds and some fish, mammals cannot regenerate cochlear hair cells. Once Tepezza damages or destroys these cells through IGF-1R blockade, the hearing loss is irreversible. This biological reality makes Tepezza ototoxicity fundamentally different from many other drug side effects that resolve when the drug is stopped.
- Cumulative Dose-Dependent Toxicity: Tepezza is administered as eight intravenous infusions over approximately 21 weeks. Clinical and post-market data indicate that otologic adverse events increase with cumulative dosing, with many patients experiencing hearing changes only after the fourth or fifth infusion — by which point significant cochlear damage may have already occurred.
- Standard Eight-Infusion Course at $300,000+: The recommended Tepezza treatment course costs approximately $300,000 per patient, creating financial pressure to complete the full regimen even when early hearing symptoms emerge. Patients who reported hearing changes mid-course were not consistently advised to discontinue treatment.
- Delayed Onset Masking Early Detection: Some patients do not experience noticeable hearing changes until weeks or months after completing Tepezza treatment, when irreversible cochlear damage has already been established. The delayed onset of symptoms complicates early detection and intervention.
Scientific Consensus
- The American Academy of Otolaryngology has acknowledged Tepezza-associated hearing loss and recommends baseline and serial audiometric monitoring for all patients receiving the drug
- Post-market studies published in peer-reviewed otolaryngology journals report hearing changes in 65% or more of Tepezza patients — far exceeding the 10% rate reported in clinical trials
- The FDA required a label update in 2023 to strengthen warnings about hearing impairment, including the potential for permanent hearing loss, tinnitus, and autophony
- IGF-1R is well-established in the otologic literature as essential for inner ear development and maintenance, with animal knockout models demonstrating profound hearing loss in the absence of IGF-1 signaling
- Multiple ENT specialists have published case series documenting severe, bilateral sensorineural hearing loss in Tepezza patients that persisted more than one year after drug discontinuation
Why This Matters for Your Case
The Tepezza hearing loss litigation centers on the manufacturer's failure to adequately warn prescribing physicians and patients about the risk of permanent sensorineural hearing loss. The clinical trial data showed a clear 10% vs. 0% hearing adverse event signal, yet the original label characterized hearing events as generally reversible and did not recommend audiometric monitoring. Post-market evidence showing 65% hearing change rates has strengthened plaintiffs' claims that the risk was significantly understated. For affected patients — many of whom are women with thyroid eye disease who were promised a life-changing treatment — the permanent loss of hearing represents a devastating and undisclosed trade-off.
Did you experience hearing loss or tinnitus after Tepezza infusions? Get a free case evaluation today.
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Internal Documents & Evidence
OPTIC Clinical Trial Data: 10% Hearing Adverse Events in Tepezza Arm vs. 0% Placebo
“The pivotal OPTIC clinical trial enrolled 83 patients with thyroid eye disease, randomized to Tepezza or placebo. In the Tepezza arm, 10% of patients experienced hearing-related adverse events including hearing impairment and tinnitus. Zero patients in the placebo arm reported hearing adverse events. This 10% vs. 0% differential represented a statistically and clinically meaningful safety signal — hearing events occurred exclusively in the drug-treated group. Despite this clear signal, the original FDA-approved prescribing information did not include a boxed warning about hearing loss, did not recommend baseline or serial audiometric monitoring, and included language suggesting that hearing events were generally reversible.”
Impact: The clinical trial hearing data is the cornerstone of failure-to-warn claims in the Tepezza litigation. Plaintiffs argue that a 10% vs. 0% hearing adverse event rate — in a trial of only 83 patients — was a definitive safety signal that obligated the manufacturer to include strong warnings and recommend monitoring. The original label's failure to do so, and its misleading suggestion of reversibility, deprived prescribers and patients of information essential to informed consent.
Sears et al. 2022: 65% Hearing Change Rate in Audiometric Study of Tepezza Patients
“A prospective audiometric study conducted at Stanford University by Sears and colleagues objectively measured hearing function in Tepezza patients before and after treatment using standard clinical audiometry. The study found that approximately 65% of patients experienced measurable hearing changes after Tepezza treatment — a rate more than six times higher than the 10% reported in the clinical trials. Critically, the clinical trials relied primarily on patient self-reporting of hearing symptoms, which significantly underestimates the true rate of hearing damage compared to objective audiometric testing. The Sears study also documented cases in which hearing loss persisted at 12-month follow-up, contradicting the label's suggestion of reversibility.”
Impact: The Sears study is the most frequently cited post-market evidence in the Tepezza litigation. It demonstrates that the clinical trial's 10% rate dramatically understated the true incidence of Tepezza-induced hearing damage, that objective audiometric testing was needed to detect hearing changes that patients might not immediately recognize, and that hearing loss can be permanent. The study's findings directly support claims that the original label was inadequate and that the manufacturer knew or should have known that the true hearing risk was far greater than disclosed.
Sifrim et al. 2023: IGF-1R Expression in Human Cochlea Confirms Biological Mechanism
“Multiple research groups have confirmed that IGF-1R is expressed at high levels in the human cochlea — specifically in outer hair cells, the stria vascularis, and spiral ganglion neurons. Animal models in which IGF-1R is knocked out or IGF-1 signaling is disrupted demonstrate progressive sensorineural hearing loss, reduced auditory brainstem response amplitudes, and degeneration of cochlear structures. This body of basic science research establishes that systemic IGF-1R blockade — the mechanism of action of Tepezza — would be expected to damage the inner ear. Critically, much of this basic science was available in the published literature before Tepezza's clinical trials were designed, raising questions about whether adequate otologic monitoring was incorporated into the trial protocol.”
Impact: The IGF-1R cochlear expression data provides the biological mechanism linking Tepezza to hearing loss. In litigation, this evidence supports the argument that Tepezza's ototoxicity was scientifically predictable based on the known role of IGF-1R in the inner ear, that the manufacturer should have anticipated hearing adverse events and designed clinical trials with objective audiometric endpoints, and that the post-market hearing loss reports are consistent with the drug's mechanism of action rather than coincidental.
Did you experience hearing loss or tinnitus after Tepezza infusions? Get a free case evaluation today.
Get Your Free Case Reviewor call 1-800-555-0100
Regulatory History of Tepezza: From Accelerated Approval to Hearing Loss Warnings
Tepezza received FDA approval in January 2020 as the first and only drug approved for thyroid eye disease (TED). The approval was based on two clinical trials totaling 170 patients. While hearing adverse events were observed in the Tepezza arm and not in the placebo arm, the original prescribing information did not include a boxed warning, did not recommend audiometric monitoring, and characterized otologic events as generally reversible. As post-market reports of permanent hearing loss, tinnitus, and autophony accumulated through the FDA Adverse Event Reporting System (FAERS), the agency required label revisions strengthening the hearing warnings — but critics argue these changes came years too late for thousands of patients already treated.
FDA approved Tepezza (teprotumumab-trbw) as the first treatment for thyroid eye disease under Priority Review. The approval was based on the OPTIC and OPTIC-X clinical trials. The prescribing information noted hearing impairment as an adverse reaction (10% Tepezza vs. 0% placebo) but did not include a boxed warning, did not recommend baseline or serial audiometry, and stated that hearing events 'resolved' in some patients without specifying the rate of persistence.
By mid-2021, the FDA Adverse Event Reporting System had received hundreds of reports of hearing impairment, tinnitus, and autophony associated with Tepezza. Reports included cases of permanent bilateral sensorineural hearing loss confirmed by audiometry, tinnitus that persisted more than one year after drug discontinuation, and cases in which hearing loss was severe enough to require hearing aids. The volume and severity of reports exceeded what would be predicted from the clinical trial data.
The FDA required Horizon Therapeutics (by then acquired by Amgen) to update the Tepezza prescribing information to include strengthened warnings about hearing impairment. The revised label acknowledged the risk of permanent hearing loss, recommended audiometric monitoring before and during treatment, and expanded the description of otologic adverse events to include autophony and eustachian tube dysfunction. The label revision did not include a boxed warning.
The American Academy of Otolaryngology published clinical guidance recommending baseline audiometry and serial monitoring for all patients receiving Tepezza. The guidance acknowledged that hearing loss associated with Tepezza can be severe, bilateral, and permanent, and recommended that patients experiencing hearing changes during treatment be promptly referred for otologic evaluation. The AAO guidance went beyond the drug label in recommending universal monitoring.
Multiple post-market studies published in the American Journal of Otolaryngology, Otology & Neurotology, and other peer-reviewed journals reported hearing change rates of 50-65% among Tepezza patients — dramatically higher than the 10% rate in clinical trials. These studies used objective audiometric testing rather than patient self-reporting, explaining the higher detection rate. Several studies documented hearing loss persisting 12+ months after drug discontinuation, contradicting the original label's suggestion of reversibility.
Significance Legend
Key Takeaway
The regulatory history of Tepezza reveals a pattern in which a clear clinical trial safety signal — 10% hearing adverse events vs. 0% placebo — was inadequately communicated in the original label, post-market evidence of much higher rates and permanent injury accumulated rapidly, and label corrections came years after thousands of patients had already been treated without appropriate audiometric monitoring or informed consent regarding the risk of permanent hearing loss.
Horizon Therapeutics and the Tepezza Revenue Story: $2 Billion Drug, $27.8 Billion Acquisition
Tepezza was the crown jewel of Horizon Therapeutics' portfolio — a rare disease drug with no competition, a captive patient population, and a list price of approximately $300,000 per treatment course. From its January 2020 approval, Tepezza rapidly became one of the highest-grossing rare disease drugs in the world, generating $1.67 billion in U.S. net sales in 2022 alone. The drug's extraordinary revenue trajectory made Horizon an acquisition target, and in December 2022, Amgen announced a $27.8 billion all-cash deal to acquire Horizon — a transaction driven overwhelmingly by Tepezza's commercial value. Throughout this period, Horizon's public communications emphasized Tepezza's efficacy and commercial potential while minimizing the emerging hearing safety signal that post-market studies would eventually reveal affected a majority of treated patients.
Timeline: Horizon Therapeutics (acquired by Amgen, October 2023)
Did you experience hearing loss or tinnitus after Tepezza infusions? Get a free case evaluation today.
Get Your Free Case Reviewor call 1-800-555-0100
State-Specific Information
Sources & References
- Hearing Dysfunction After Treatment With Teprotumumab for Thyroid Eye Disease — Prospective study finding 65% of patients experienced audiometric changes — Endocrine Society / American Journal of Ophthalmology (2022) [Link]
- FDA Updates Tepezza Prescribing Information to Include Warning of Severe and Possibly Irreversible Hearing Impairment (July 2023) — U.S. Food and Drug Administration (FDA) [Link]
- Audiology Findings in Patients with Teprotumumab-Associated Otologic Symptoms — 81.5% developed new otologic symptoms after mean 3.8 infusions — PMC / National Library of Medicine [Link]
- In re: Tepezza (Teprotumumab) Products Liability Litigation — MDL No. 3079, N.D. Illinois, Judge Thomas M. Durkin — U.S. District Court, Northern District of Illinois
- Hearing Loss and Teprotumumab — Review of IGF-1R pathway role in cochlear hair cell survival and ototoxicity mechanism — PMC / National Library of Medicine [Link]