Tepezza, a drug used to treat thyroid eye disease, has come under scrutiny for leaving people with permanent hearing loss, including tinnitus and deafness. To date, at least 34 lawsuits have been filed against Horizon Pharmaceuticals Inc., claiming that the company did not properly warn people of this potentially permanent side effect. 

The drug earned FDA approval in 2020, and since then, hearing loss and other hearing-related side effects have come pouring in. Below, find a timeline of the Tepezza lawsuits and related events.  

2013: The FDA granted Orphan Drug and later fast-track designation to teprotumumab

Teprotumumab is the active ingredient in Tepezza. Orphan drug designation can be given to drugs that are intended to diagnose, treat, or prevent a rare disease or condition. The designation gives companies tax credits for clinical trials, exemption from user fees, and the potential for seven years of market exclusivity after approval. 

Fast-track designation helps speed up the process of approving a new drug. Drugs can be given this designation if they treat serious or life-threatening conditions and address unmet medical needs. 

2016: The FDA granted Breakthrough Therapy Designation to teprotumumab

Breakthrough therapy designation is given to drugs that are intended to treat serious conditions. Preliminary clinical evidence must show that the drug provides a substantial improvement over other currently available treatments. This designation can help expedite the development and review of the drug. 

January 2020: Tepezza approved by the FDA

Tepezza was approved by the FDA to treat thyroid eye disease (TED), and it is the only drug that has been approved for this condition. Because symptoms of TED can be devastating and affect quality of life, many people were excited to have a treatment available and didn’t hesitate to begin treatment. Symptoms of TED can include pain, trouble moving eyes, difficulty closing eyes, bulging eyes, and blurred vision. 

The Tepezza warning label did not include a warning about deafness and hearing-related issues. 

May and June 2020: Reports of tinnitus after Tepezza use

Shortly after the drug was approved, people started to report instances of tinnitus, which is characterized by hearing ringing or other noises in the ear. 

July 2020 to December 2020: Continued reports of hearing issues including deafness 

Month after month, Horizon continued to report incidents of hearing loss and other hearing issues to the FDA. Some common issues included tinnitus, hearing loss, and deafness in one or both ears. 

October 2021: Horizon Pharmaceuticals began its postmarketing study 

Postmarketing clinical trials are conducted after a drug has been approved by the FDA and is available to the public. They help companies collect data on things like safety, efficacy, and optimal use. Horizon began their study over a year after the drug was first approved by the FDA. 

February 2022: Horizon released the results of the postmarketing study 

Preliminary data from the Tepezza postmarketing study showed that about 10% of people experienced a hearing-related event after being treated with Tepezza.  

March 2021: A study found up to 65% of people that take Tepezza have hearing issues

A separate study that included 26 patients taking Tepezza found a much higher percentage of hearing-related events. In the study, 65% of people suffered from hearing issues after taking the drug for TED. These included subjective hearing loss, tinnitus, an ear plugging sensation, and autophony (a condition where your own voice or other noises within your body sound exceptionally loud). 

January to September 2022: Continued reports of hearing issues 

Many people continued to report hearing-related issues, including deafness, hearing loss, and tinnitus. 

August 2022: The first Tepezza lawsuit is filed 

A man who developed permanent hearing loss after taking Tepezza filed the first lawsuit against Horizon Pharmaceuticals. 

December 2022: Horizon Pharmaceuticals announces it will be acquired by Amgen 

Amgen and Horizon Pharmaceuticals announced that Amgen would acquire Horizon for upwards of $27 billion. 

January 2023: Amgen investors attempt to block the acquisition 

Worried about litigation, many Amgen investors attempted to block the acquisition of Horizon Pharmaceuticals. 

March 2023: At least 34 Tepezza lawsuits have been filed, and a motion is filed to make the lawsuits an MDL

As of March 2023, at least 34 Tepezza lawsuits have been filed, most claiming that Tepezza caused hearing-related issues including permanent hearing loss. Those affected claim that Horizon was aggressive in their drug marketing and that they did not disclose the risks of hearing-related issues such as permanent hearing loss and deafness. 

Thirteen of the lawsuits may have been settled out of court as they have been dismissed. 

There was also a motion filed to make the Tepezza lawsuits a class action MDL. There are currently 18 cases pending across five districts, and the preferred venue for the MDL is the Northern District of California. 

April 2023 and beyond: Tepezza lawsuits continue to grow, label is updated but does not include information on hearing loss

A Stanford case study found that the risk of hearing loss is less when the Tepezza dose is lower. In the case study, a woman who had previously experienced hearing loss after taking Tepezza repeated treatment a year later but at a lower dose. During her second treatment, she did not experience hearing loss.  

The Tepezza lawsuits will likely continue to grow in number through 2023. 

The Tepezza label was updated to change the indication. The drug can now be used for thyroid eye disease regardless of disease activity or duration. This makes it easier for people to access the drug and may reduce the time it takes someone to begin receiving treatment. 

At this time, there has been no recall of Tepezza, and there has been no warning added to the label regarding the dangers of hearing loss and other hearing-related issues.