Tepezza infusions treat thyroid eye disease (TED), but new evidence shows they can cause permanent hearing loss. Individuals who suffered severe hearing damage from Tepezza are now filing product liability lawsuits against the manufacturer, Horizon Therapeutics.
One of the most recently filed Tepezza lawsuits is Diaz v. Horizon Therapeutics USA, Inc. (1:23-cv-00896), filed in the U.S. District Court for the Northern District of Illinois on February 14, 2023. The Diaz case is a good example of the types of allegations being made against Horizon Therapeutics in connection with Tepezza hearing loss claims. In this post, we will provide a detailed summary of this case in which the plaintiff alleges hearing loss from Tepezza infusions.
Facts of the Case
The plaintiff, Norma Perez Diaz, is a California resident and citizen. The single defendant named in the case is Horizon Therapeutics USA, Inc. (“Horizon”) which is the company that manufactures and sells Tepezza.
According to the Complaint, Norma was diagnosed with thyroid eye disease and/or Graves’ disease and received Tepezza infusions from November 2021 through April 2022. However, the Complaint asserts that neither Norma nor her physicians were given any warning or knowledge of the severe risk of permanent hearing loss and/or tinnitus posed by Tepezza.
This Tepezza lawsuit contends that Horizon did not indicate or warn that Tepezza could cause permanent hearing damage. Moreover, physicians were not directed by Horizon to conduct baseline audiology testing before treatment with Tepezza or monitor hearing acuity during treatment.
The Complaint alleges that as a direct result of receiving infusions of Tepezza, Norma now suffers from permanent hearing loss and/or tinnitus. Her lawsuit contends that Horizon negligently failed to warn about the true risk of hearing loss associated with Tepezza.
About Thyroid Eye Disease (TED)
Thyroid eye disease, also known as TED, is a condition characterized by inflammation in the tissues surrounding the eyes, causing discomfort, redness, and swelling of the eyelids. In some cases, the eyes may bulge or push forward, known as proptosis. While Horizon’s marketing materials suggested that vision impairment was common among patients diagnosed with TED, this outcome is rare, affecting only 3-5% of patients.
It is believed that TED is an autoimmune disease associated with hyperthyroidism, though the exact mechanism of the disease is not fully understood. Symptoms can vary widely between individuals, ranging from mild to severe, including redness, irritation, discomfort, and dryness of the eyes and eyelids, pain when moving the eyes, and eyelid retraction.
The active phase of TED can last from six months to two years and is followed by an inactive phase, during which the patient’s condition does not worsen. Treatment for TED typically involves reversing hyperthyroidism in individuals with underlying Graves’ disease and supportive measures such as wearing dark sunglasses and using artificial tears.
Development of Tepezza
Horizon designed Tepezza to treat thyroid eye disease and sought FDA approval for the drug. In May 2013, the FDA granted Orphan Drug designation for teprotumumab, which provides a separate pathway for approval and qualifies sponsors for incentives such as tax credits for clinical trials, exemption from user fees, and up to seven years of market exclusivity post-approval.
In January 2020, the FDA approved Tepezza as the first drug indicated to treat TED. It works by inhibiting the activity of the protein insulin-like growth factor-1, believed to play a significant role in the development of the disorder. While the severity of TED is distinct from disease activity, severity is best defined by functional or cosmetic impairment.
Despite this, Horizon marketed Tepezza for use by anyone diagnosed with TED and for early treatment of the disease. In 2021, the EUGOGO issued clinical practice guidelines recommending Tepezza as a second-line treatment for moderate-to-severe and active Graves’ orbitopathy, noting that its incorporation into routine clinical practice is currently limited by the lack of comprehensive long-term efficacy and safety data, absence of head-to-head comparison with i.v. glucocorticoids, restricted geographical availability, reimbursement (outside the U.S.), and costs.
Failure to Test Tepezza
The Tepezza label, which provides information on the drug’s use, states that the drug’s mechanism of action in treating Thyroid Eye Disease (TED) is not fully understood. According to the label, Tepezza works by binding to IGF-1R and blocking its activation and signaling. But the defendant did not conduct tests to determine the exact mechanism of action of the drug. The label also admits that no formal pharmacodynamic studies have been conducted with teprotumumab-trbw, indicating that the drug’s safety was not thoroughly tested before approval.
The safety and efficacy of Tepezza were evaluated in two randomized, double-masked, placebo-controlled clinical studies consisting of 170 patients with TED. Of those patients, 84 received Tepezza, and 86 received a placebo. However, the label for Tepezza contains warnings for infusion reactions, exacerbation of preexisting inflammatory bowel disease, and hyperglycemia. The only reference to hearing loss on the label is listed among the adverse reactions, with eight Tepezza users experiencing some form of hearing impairment compared to none in the placebo group. The label does not mention whether any adverse events are permanent or the duration of the symptoms, nor does it mention tinnitus.
Moreover, regardless of which representation on the Tepezza label regarding the total number of study participants is accurate, Tepezza was submitted to FDA for approval with less than 100 patients receiving the drug in clinical trials. That is not a lot of patients. This raises concerns about the drug’s efficacy and safety, particularly given the warnings listed on the label.
Post-Market Testing of Tepezza
According to the Complaint, Horizon’s 2021 Annual Report, it delayed the start of an FDA-required post-marketing study to evaluate the safety of Tepezza in a larger patient population and retreatment rates. The study eventually began in the fourth quarter of 2021. However, in the interim, the defendant continued to market and sell Tepezza.
On February 22, 2022, Horizon issued a press release announcing the results of a new post-marketing safety analysis of hearing events associated with Tepezza for treating Thyroid Eye Disease. These findings were presented at the 48th Annual Meeting of the North American Neuro-Ophthalmology Society. Thousands of patients were included in this 19-month analysis, and the results demonstrated that approximately 10% of all cases reported to the safety database included a hearing-related event. The most frequently reported hearing event was hyperacusis (reduction in hearing), followed by tinnitus (ringing in the ears). The defendant continued to assert that most hearing-related adverse events in the pivotal trials and post-approval have been mild to moderate and reversible.
However, almost immediately after the FDA approved Tepezza, patients and doctors began reporting serious complications related to ear and permanent hearing problems in patients taking Tepezza.
Plaintiff’s Tort Claims
The Complaint alleges that Norma began receiving Tepezza infusions in November 2021 to treat her thyroid eye disease. She continued receiving Tepezza infusions through April 2022. It was at that point, before her Tepezza infusion treatment was even finished, that Norma experienced an adverse immune system reaction that resulted in significant hearing loss.
The Complaint asserts four claims against Horizon: (1) Strict Liability Failure to Warn, (2) Strict Liability Design Defect, (3) Negligent Failure to Warn, and (4) Negligent Design Defect. The Complaint also asserts a separate claim for punitive damages.
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