Tepezza Litigation Updates

Teprotumumab can cause permanent hearing loss. Plaintiffs allege that the manufacturer, Horizon Pharmaceuticals, failed to warn doctors and patients that hearing loss may be permanent and that no formal guidelines for audiometric monitoring were offered. The first lawsuit has been filed in the Northern District of Illinois, and thousands more are expected.

The first lawsuit against Tepezza was filed on August 25, 2022, by Daniel Weibel, a Tepezza patient who has experienced permanent total hearing loss as a result of taking the drug.

Teprotumumab was approved by the FDA in January 2020 as the first medication for thyroid eye disease, a debilitating condition that causes inflammation of the eyes leading to redness, irritation, and bulging.

This drug received priority review with Fast Track and Breakthrough Therapy designation, resulting in faster approval. It is marketed under the brand name Tepezza.

While the medication effectively treats thyroid eye disease, patients have experienced unexpected side effects related to hearing, some of which have been permanent.

Tepezza Background Information

Teprotumumab is administered as an IV infusion every three weeks for eight doses. According to Horizon Therapeutics PLC, the side effects include:

According to the drugmaker, hearing problems occurred in 10 percent of patients studied and may include deafness, fluid plugging of the ears, and impairment in perceiving the loudness of sounds.

The drugmaker claimed that side effects were mild or moderate and that they resolve during or after treatment. Horizon has not mentioned in any of its literature that hearing problems may be permanent.

Teprotumumab Studies

Horizon Therapeutics PLC obtained FDA approval for teprotumumab after conducting two placebo-controlled studies of 170 patients. The drug maker reported that 10 percent of patients who received teprotumumab experienced temporary mild to moderate hearing symptoms.

However, independent studies found a higher prevalence of hearing symptoms and evidence of irreversible hearing loss.

Hearing Symptoms in 65 Percent of Subjects

A study reported by the Endocrine Society on May 3, 2021, showed that 65 percent of subjects experienced hearing symptoms after an average of 3.6 infusions. The symptoms included:

  • Autophony
  • Tinnitus
  • An ear-plugging sensation
  • Hearing loss
  • Muffled hearing

Testing revealed that some of the patients experiencing hearing loss had developed sensorineural hearing loss, a condition caused by damaged hair cells in the inner ear. Only half of the patients with sensorineural hearing loss experienced improvements.

Patients with patulous eustachian tube dysfunction, the condition responsible for the ear-plugging sensation and autophony, experienced some improvement but not complete resolution.

Hearing Symptoms in 81.5 Percent of Subjects

Another study published by the American Journal of Ophthalmology in February of 2022 found that as many as 81.5 percent of patients developed hearing symptoms after a mean of 3.8 infusions.

In a follow-up approximately 9 months after the last infusion, researchers found that sensorineural hearing loss only resolved in 45.5 percent of patients with these symptoms.

Tepezza Background Information

Insulin-like growth factor-1 (IGF-1) is a molecule found throughout the body with various functions in nearly every body system. It plays important roles in the cellular metabolism and maintenance of the inner ear, including the prevention of cell death in hair cells located in the inner ear, which are critical to hearing.

Teprotumumab inhibits the IGF-1 signaling pathway by targeting the IGF-1 receptor. This creates an IGF-1 deficiency, potentially causing the death of hair cells in the inner ear and resulting in sensorineural hearing loss.

Current Tepezza Litigation

The first lawsuit against Tepezza is Daniel Weibel vs. Horizon Pharmaceuticals Inc., case number 22-cv-4518, filed on August 25, 2022, in the Northern District of Illinois. The defendant is Horizon Therapeutics PLC, misnamed Horizon Pharmaceuticals Inc. Thousands more cases are expected to be filed.

The lawsuit alleges that Horizon had a duty to protect the public by:

  • Providing a label with adequate warnings
  • Performing post-marketing monitoring and safety research
  • Revising the label when reasonable evidence of permanent hearing loss came to light


The plaintiff alleges that Horizon violated its duty of care with the following acts and omissions:

  • Misrepresenting and withholding information from the FDA and the public
  • Ignoring the association between hearing loss and Tepezza
  • Failing to warn the plaintiff and the plaintiff’s health care providers of the real risk of hearing damage
  • Failure to instruct health care providers to monitor hearing complications


The plaintiff is seeking punitive damages on the following grounds:

  • Reckless disregard for human life and the safety of patients exposed to Tepezza
  • Wantonness, recklessness, and a grossly careless disregard for public safety

The plaintiff alleges that Horizon’s preapproval research was insufficient, with only 84 subjects receiving the drug. The lawsuit also alleges that Horizon knew or should have known that IGF-1 disruptors correlate with hearing loss.

While seeking FDA approval, Horizon mischaracterized the hearing loss as mild and of limited duration, according to the lawsuit.

After the drug was approved, Horizon failed to investigate reports that patients were experiencing irreversible hearing loss, despite numerous studies bringing this information to light.

Doctors and patients also reported serious hearing side effects almost immediately after approval, but the company continued to characterize the hearing loss as mild and temporary.

The company failed to instruct doctors to provide audiometric monitoring during treatment. Audiometric monitoring could have allowed patients to make an informed choice about continuing treatment. It is common practice for ototoxic medications to recommend such monitoring.

When studies and patient reports revealed the true risk of permanent hearing loss, the company could have revised the label by utilizing the FDA’s “Changes Being Effected” supplement to provide the updated information.

The company aggressively marketed a dangerous product without warning the public of its risks. In 2021 alone, sales of Tepezza reached $1.66 billion.

Horizon’s Response

Horizon Therapeutics PLC claims its warnings were adequate. The company denies that the new information was sufficient to justify changing the label.

Tepezza Case Management for Your Firm

Case Works can help your law firm prepare for Tepezza cases and handle all aspects of intake, case management, and client retention.