Tepezza hearing loss lawsuit: where MDL 3079 actually stands heading into bellwether trials

The Tepezza litigation tests whether a pharmaceutical manufacturer can be held liable for failing to warn about serious adverse effects that emerged in clinical trials but weren't included in the FDA-approved label until years after the drug was marketed. MDL 3079 (In re: Tepezza Hearing Loss Litigation), centralized in the U.S. District Court for the Northern District of Illinois before Judge Thomas M. Durkin, consolidates approximately 275 cases as of mid-2026 alleging that Tepezza (teprotumumab-trbw), the first FDA-approved treatment for thyroid eye disease, caused permanent hearing loss and tinnitus in patients who received the infusions. Horizon Therapeutics manufactured and marketed Tepezza from FDA approval in January 2020 until Amgen acquired Horizon in October 2023 for $27.8 billion. Amgen now defends the litigation as the surviving entity.

The substantive case focuses on Horizon's failure to warn about hearing-related adverse effects between FDA approval in January 2020 and the FDA-mandated label update in July 2023. Internal documents produced through discovery show that Horizon received reports of tinnitus and hearing loss as early as May and June 2020 (within months of approval), but the label warning wasn't added for more than three years. During that period, doctors and patients prescribing and receiving Tepezza had no formal warning about the hearing risks. The 2023 label update required physicians to assess patients' hearing before, during, and after treatment, but the warning came too late for the thousands of patients treated during the unwarned period.

The litigation is procedurally smaller than most major mass torts but the bellwether framework is mature. Twelve cases were selected for bellwether discovery in June 2024. The first bellwether trial is scheduled for August 3, 2026, with three subsequent trials on September 28, 2026, November 30, 2026, and February 1, 2027. Each trial is expected to last three to four weeks. The court has been working through Daubert challenges (largely resolved in plaintiffs' favor), expert depositions, and pre-trial motions to prepare the cases for trial. The relatively small case count (compared to mass torts with tens of thousands of plaintiffs) and the concentrated bellwether schedule make Tepezza one of the more procedurally accelerated current mass torts.

This is the science behind the Tepezza-hearing loss connection, the procedural history of MDL 3079, the eligibility framework for filing claims, the bellwether trial framework, and the strategic considerations for current and prospective plaintiffs.

What is Tepezza and how does it work?

Tepezza (teprotumumab-trbw) is a monoclonal antibody and the first FDA-approved treatment for thyroid eye disease (TED). It blocks the IGF-1R receptor to reduce inflammation and eye bulging. Approved in January 2020, it is given as eight intravenous infusions over five months, with total treatment costs typically between $250,000 and $400,000.

Tepezza (teprotumumab-trbw) is a monoclonal antibody designed to treat thyroid eye disease (TED), a rare autoimmune disorder also known as Graves' Orbitopathy. The disease causes inflammation and bulging of the eyes, leading to symptoms ranging from dry eyes and visual disturbances to severe disfigurement and vision loss in extreme cases.

The condition itself:

Autoimmune mechanism. In thyroid eye disease, the immune system mistakenly attacks the tissue around the eyes, triggering inflammation. The mechanism involves antibodies that activate the insulin-like growth factor-1 receptor (IGF-1R) on tissue cells in the eye area.

IGF-1R activation effects. Activated IGF-1R causes overproduction of fibroblasts (connective tissue cells), which produces the characteristic eye bulging, eyelid retraction, eye muscle dysfunction, and other symptoms of TED.

Prevalence. TED affects approximately 16 in 100,000 people in the U.S. annually. Most cases are mild and resolve with conservative treatment. A minority of cases progress to severe forms requiring active intervention.

How Tepezza works:

Mechanism. Tepezza binds to IGF-1R and blocks its activation, interrupting the disease process. The drug was the first targeted therapy specifically designed for TED.

Administration. Tepezza is given as eight intravenous infusions over approximately five months, one infusion every three weeks. Each infusion takes 60-90 minutes.

FDA approval pathway. The FDA approved Tepezza in January 2020 through expedited review pathways. Horizon Therapeutics received Orphan Drug designation in 2013, fast-track designation in 2013, and Breakthrough Therapy Designation in 2016. The Biologics License Application was submitted in July 2019 and approved in January 2020.

Market position. Tepezza was marketed as a breakthrough therapy for a previously untreatable condition. Horizon priced the drug at approximately $14,000 per vial, with total treatment cost typically $250,000-$400,000 per patient.

How does Tepezza cause hearing loss?

Tepezza causes hearing loss by blocking IGF-1R receptors present in cochlear hair cells, the sensory cells responsible for hearing. Reports of tinnitus and hearing loss surfaced within months of FDA approval in 2020, but the FDA did not require a label warning for severe and permanent hearing loss until July 2023, more than three years later.

The connection between Tepezza and hearing loss emerged shortly after FDA approval:

Clinical trial data. Hearing impairment was identified as a potential adverse event during the Tepezza clinical trials. Horizon's pivotal Phase III trials included some reports of hearing-related adverse events.

FDA advisory committee. Hearing impairment was discussed at the FDA advisory committee meeting before approval. Horizon characterized the risk as modest.

Initial label. The original FDA-approved label included some reference to hearing-related adverse events but characterized them as relatively minor and typically reversible.

Early post-market reports. The FDA received the first adverse event report of tinnitus following Tepezza use on May 13, 2020, just four months after FDA approval. By June 2020, the FDA had received four reports from Horizon of patients experiencing tinnitus and hearing loss.

Mounting evidence. Reports continued through 2020, 2021, and 2022. By 2022, peer-reviewed studies were documenting hearing-related adverse effects in larger patient populations. A 2024 case series following 22 Tepezza-treated patients found that 39% of ears experienced hearing loss meeting ototoxicity criteria.

July 2023 label update. The FDA required Horizon to update Tepezza's label to include a warning for severe and permanent hearing loss. The updated label instructed physicians to assess patients' hearing before, during, and after Tepezza infusions. The warning came more than three years after FDA approval and more than three years after the first adverse event reports.

The science of how Tepezza causes hearing damage:

IGF-1R in cochlear hair cells. The same IGF-1R receptors that Tepezza blocks in eye tissue are present in cochlear hair cells (the sensory cells responsible for hearing). When Tepezza blocks IGF-1R activity systemically, it may interfere with cochlear hair cell function.

Direct ototoxicity. Multiple otologists and pharmacologists have submitted expert testimony in MDL 3079 connecting teprotumumab to inner ear damage. The mechanism is believed to involve direct ototoxicity from the drug's effect on cochlear cells.

Subtle damage profile. Research suggests that hearing loss from Tepezza can be subtle, delayed, or fall outside the range of standard audiometry. Some patients suffer ototoxic damage that doesn't show up clearly on standard hearing tests, leading to undiagnosed impairment.

Permanence. The most concerning aspect is that hearing damage from Tepezza appears to be largely permanent. Unlike some ototoxic effects that resolve after the drug is discontinued, Tepezza-related hearing loss persists in most affected patients.

What hearing conditions are alleged in Tepezza lawsuits?

Plaintiffs in MDL 3079 allege several hearing and ear-related conditions caused by Tepezza, including permanent sensorineural hearing loss, persistent tinnitus, hyperacusis, autophony, eustachian tube dysfunction, and inner ear injury. These conditions may occur individually or in combination, often with substantial impact on daily functioning and quality of life.

Plaintiffs in MDL 3079 allege various hearing and ear-related conditions caused by Tepezza:

Permanent sensorineural hearing loss. The most severe and most common claimed condition. Sensorineural hearing loss involves damage to the inner ear or auditory nerve and is typically permanent.

Tinnitus. Persistent ringing, buzzing, or other phantom sounds in the ears. Can range from mild and intermittent to severe and constant. Tinnitus from ototoxic medications is often permanent.

Hyperacusis. Abnormal sensitivity to normal-volume sounds. Sounds that wouldn't bother most people cause significant discomfort or pain.

Autophony. Hearing one's own body sounds at abnormal volume: breathing, heartbeat, swallowing, speech. Indicates abnormal middle or inner ear function.

Eustachian tube dysfunction. Problems with the eustachian tube affecting ear pressure regulation. Can cause feeling of fullness, popping, or imbalanced pressure between ears.

Inner ear injury. Various forms of inner ear damage including labyrinthitis-like conditions, vertigo, and balance problems.

Ear fullness or pressure sensations. Persistent sensation of fullness or pressure in the ears that doesn't resolve.

The conditions can occur individually or in combination. Severe cases involve multiple conditions simultaneously, with substantial impact on daily functioning, employment, and quality of life.

What is the procedural history of MDL 3079?

MDL 3079 was formed in June 2024 in the Northern District of Illinois before Judge Thomas M. Durkin, consolidating approximately 275 Tepezza hearing loss cases. Twelve bellwether cases were selected, with the first trial scheduled for August 3, 2026. Fact discovery closed in May 2025, and Daubert challenges have been largely resolved in plaintiffs' favor.

The litigation has developed:

Late 2022. First Tepezza hearing loss lawsuits filed. Early cases focused on permanent hearing loss and tinnitus claims.

March 2023. Motion to consolidate cases into MDL filed with the JPML.

May 25, 2023. JPML held oral arguments on consolidation motion.

June 2024. MDL 3079 formed in the Northern District of Illinois before Judge Thomas M. Durkin.

June 11, 2024. Twelve cases designated as bellwether pool for case-specific discovery.

Throughout 2024-2025. Discovery proceeded. Plaintiff and defense experts deposed. Case-specific discovery on bellwether cases.

May 9, 2025. Fact discovery closed. Expert discovery began.

June 9, 2025. Expert reports submitted.

August 22, 2025. First bellwether trial date adjusted to August 3, 2026 (from earlier scheduled date), with three subsequent trials on September 28, 2026, November 30, 2026, and February 1, 2027.

Throughout 2025-2026. Daubert challenges and pre-trial motions resolved. Court denied Horizon's (Amgen's) motion to dismiss the entire litigation. Court denied Amgen's attempts to exclude critical plaintiff expert testimony from a leading otolaryngologist linking teprotumumab to irreversible cochlear damage.

Settlement discussions. Judge Durkin has directed parties to meet for settlement talks at least once per quarter. As of mid-2026, no global settlement has been reached, but the settlement framework is developing as bellwether trials approach.

Who is eligible to file a Tepezza hearing loss claim?

Eligibility for a Tepezza hearing loss claim requires documented Tepezza use, a diagnosed qualifying condition such as permanent sensorineural hearing loss or persistent tinnitus, temporal proximity between treatment and symptom onset, supporting audiology documentation, and compliance with state statutes of limitations. The strongest claims involve patients treated between January 2020 and July 2023, before the label update.

The framework for filing Tepezza claims:

Documented Tepezza use. Records showing the claimant received Tepezza infusions. Medical records, infusion center records, prescription documentation, or insurance records. The dosage and timing of infusions should be documented.

Diagnosed qualifying condition. Medical records establishing one of the qualifying conditions:

• Permanent sensorineural hearing loss
• Persistent tinnitus
• Hyperacusis
• Inner ear injury or damage
• Eustachian tube dysfunction (in some firms' frameworks)

Treatment of TED. The claimant received Tepezza for the treatment of thyroid eye disease (or related off-label uses). Tepezza prescribed for unrelated conditions wouldn't typically fit the MDL framework.

Temporal proximity. The hearing-related condition emerged during or after Tepezza treatment. The timeline should be consistent with Tepezza-related ototoxicity rather than pre-existing or unrelated hearing problems.

Audiology documentation. Audiograms or other audiology testing showing hearing loss patterns consistent with ototoxic injury. Standard audiometry may miss some Tepezza-related damage (subtle or high-frequency), so additional testing (high-frequency audiometry, otoacoustic emissions, etc.) may be needed for some cases.

Statute of limitations compliance. State-specific limitations periods apply, typically 2-4 years from injury or discovery. Some state deadlines are expiring in 2026 for patients treated between 2020 and 2022, making timely filing increasingly important.

No significant alternative causation. Cases involving strong alternative causes for hearing loss (occupational noise exposure, other ototoxic medications, hereditary hearing loss, etc.) face more difficult causation analysis.

The strongest typical case profile:

A patient who received Tepezza between January 2020 and July 2023 (the period of inadequate warning), developed permanent sensorineural hearing loss documented through audiology testing, has comprehensive medical records establishing the timeline, and has no significant alternative causation. Cases involving patients treated after the July 2023 label update face more difficult failure-to-warn arguments because the warning was provided.

What are the expected Tepezza lawsuit settlement amounts?

No global settlement has been reached as of mid-2026.

Settlement range. $140,000 to $500,000 per case for favorable facts. Severe cases may exceed this range; less severe cases may fall below.

Influenced by bellwether outcomes. The first bellwether trial verdict in August 2026 will substantially affect settlement framework.

Possibly accelerated settlement. Some analysts predicted potential settlement before the first bellwether trial, particularly given Amgen's acquisition of Horizon and the strategic implications for Amgen's broader operations.

The case count of ~275 makes Tepezza a smaller litigation than many mass torts in dollar terms (total exposure perhaps $50-150 million depending on outcomes). The relatively small scale may favor faster resolution than larger mass torts produce.

How does the Tepezza lawsuit compare to other mass torts?

The Tepezza litigation is smaller than most major mass torts (approximately 275 cases) but procedurally advanced. Unlike the Zantac MDL, Tepezza survived Daubert challenges. Unlike the Philips CPAP litigation, it is proceeding through bellwether trials rather than settling early. Total litigation exposure is estimated at $50 to $150 million.

The litigation has distinctive features:

The broader procedural framework for mass tort settlements is detailed in our overview of how mass tort litigation works. Tepezza represents one of the smaller-scale but procedurally advanced current mass tort litigations.

What should Tepezza plaintiffs consider before filing?

Prospective Tepezza plaintiffs should file promptly because state statutes of limitations are expiring throughout 2026 for patients treated between 2020 and 2022. Key steps include engaging experienced counsel, obtaining comprehensive audiology documentation (including high-frequency testing), and assembling detailed treatment timeline records. First bellwether trials begin August 2026.

For potential plaintiffs:

Don't delay filing. State statutes of limitations are expiring throughout 2026 for patients treated between 2020 and 2022. The discovery rule may extend limitations in some cases, but the rule has limits. Early filing preserves claim viability.

Engage Tepezza-experienced counsel. The MDL is procedurally specific and benefits from counsel with established Tepezza case experience. Most plaintiffs' firms work on contingency basis (typically 30-40% of recovery).

Obtain comprehensive audiology documentation. Standard audiometry may miss subtle Tepezza-related damage. High-frequency audiometry, otoacoustic emissions testing, and ototoxicity-specific evaluations may be needed. Coordinate with audiologists familiar with ototoxic injury patterns.

Document the treatment timeline. Detailed records of Tepezza infusion dates, dosages, prescribing physician, infusion center, and related details. Records of pre-Tepezza hearing baseline (if available) and post-Tepezza changes.

Be realistic about timeline. First bellwether trials begin August 2026. Resolution of remaining cases through settlement or post-bellwether procedures may take through 2027 or beyond. Plan for extended litigation timelines.

Consider audiology baselining. For patients currently receiving Tepezza or considering treatment, comprehensive pre-treatment audiology baseline testing creates important documentation if hearing loss subsequently develops.

Coordinate with treating audiologists. Audiologists familiar with the Tepezza litigation can provide more useful documentation than general otology practices. The case strength depends substantially on audiology evidence.

Watch for settlement framework development. If global settlement occurs before bellwether trials, the settlement implementation procedures will be different from post-trial settlements. Monitor settlement framework developments and ensure timely participation in any settlement opportunities.

The Tepezza litigation represents a procedurally focused case against a major pharmaceutical manufacturer who allegedly delayed warnings about serious permanent adverse effects for more than three years after the effects became apparent. For patients who received Tepezza during the unwarned period (January 2020 - July 2023) and developed permanent hearing damage, the framework provides meaningful paths to compensation. The August 2026 bellwether trial will substantially affect the resolution framework for remaining cases. For potential plaintiffs, engagement with experienced counsel, comprehensive medical documentation, and timely filing within applicable limitations periods are the procedural steps that preserve eligibility for participation in whatever resolution framework emerges. The science is strong, the procedural framework is mature, and the bellwether trials should produce meaningful resolution within the next 12-18 months.