Amgen's TEPEZZA continues to dominate the thyroid eye disease (TED) treatment landscape, generating $1.9 billion in sales for the full year 2024, with $460 million in the fourth quarter alone. This strong performance underscores the significant unmet need that existed before TEPEZZA's introduction as the first FDA-approved therapy specifically for TED.
The global thyroid eye disease market, valued at $2.3 billion across seven major markets in 2023, is projected to experience substantial growth through 2034, according to market analysis from DelveInsight. This expansion is primarily driven by increasing disease awareness and a rising prevalence of TED, with the United States representing the largest market segment.
Breakthrough Treatment for a Debilitating Condition
Thyroid eye disease is a rare but serious autoimmune condition affecting the eyes, commonly associated with hyperthyroidism or Graves' disease. Approximately 25-50% of people with Graves' disease develop TED, with women more frequently affected than men. In 2023, there were approximately 1.4 million diagnosed prevalent cases of TED across the seven major markets, with this number expected to increase by 2034.
TEPEZZA (teprotumumab-trbw), a fully human IgG1 monoclonal antibody, works by inhibiting insulin-like Growth Factor-1 receptor (IGF-1R). While its exact mechanism of action in Graves' ophthalmopathy isn't fully understood, it binds to IGF-1R, inhibiting its activation and signaling pathways that contribute to the inflammatory process in TED.
Dr. Kikkawa from Ophthalmology Times noted, "The introduction of TEPEZZA has significantly impacted TED treatment, leading to a reduction in the need for orbital decompression surgeries at their center."
Treatment Protocol and Administration
The prescribed dosage of TEPEZZA involves an initial intravenous infusion of 10 mg/kg, followed by 20 mg/kg infusions every three weeks for a total of seven additional doses. Each single-dose vial contains 500 mg of teprotumumab, along with various excipients, and when reconstituted, yields a final concentration of 47.6 mg/mL.
According to Dr. Tamhankar from Eyes On Eyecare, "The patients exhibiting active disease symptoms—such as significant diplopia, proptosis, and a high Clinical Activity Score (CAS)—respond most favorably to TEPEZZA."
Currently, TEPEZZA is being evaluated in Phase III clinical trials for patients with moderate-to-severe active Graves' orbitopathy and chronic thyroid eye disease with a low Clinical Activity Score. Amgen is also investigating its potential for subcutaneous administration, which could improve convenience compared to the current intravenous formulation.
Expanding Global Footprint
TEPEZZA's market presence continues to grow internationally. In September 2024, Japan's Ministry of Health, Labour and Welfare approved TEPEZZA for the treatment of active Graves' orbitopathy. Additionally, in April 2024, Amgen announced plans to submit a Marketing Authorization Application to the European Medicines Agency, potentially expanding access to European patients in the near future.
The drug's development has been accelerated through various regulatory pathways, including Breakthrough Therapy Designation (2016), Fast Track Designation (2015), and Orphan Drug Designations in both the US and Japan.
Competitive Landscape Evolution
While TEPEZZA currently dominates the TED treatment market, several competitors are developing alternative therapies that could reshape the landscape in the coming years. Key companies in this space include:
- Immunovant, developing IMVT-1401 (batoclimab) and IMVT-1402
- Viridian Therapeutics, with VRDN-001 (veligrotug) and VRDN-003
- Argenx, developing Efgartigimod PH20 SC
- Tourmaline Bio, with Pacibekitug (TOUR006)
- Hoffmann-La Roche, developing ENSPRYNG
- Sling Therapeutics, with Linsitinib
Notably, in January 2025, Sling Therapeutics announced topline results for linsitinib from their Phase IIb/III LIDS trial in patients with active, moderate to severe TED. As an oral small molecule taken twice daily, linsitinib could offer a more convenient alternative to intravenous infusions if approved.
Viridian Therapeutics stands out as the only company developing treatments for both moderate to severe active TED and chronic TED. Their veligrotug trials feature a five-dose regimen with fewer infusions and shorter administration times than TEPEZZA, potentially positioning it as a strong competitor.
Market Dynamics and Future Outlook
The TED treatment market is expected to undergo significant transformation in the coming years. Currently, only about 20% of TED cases are acute and receive treatment, suggesting substantial room for market growth as safer and more effective therapies become available.
TEPEZZA's first-mover advantage, established prescriber base, and the strong unmet need in the TED market are expected to sustain its revenue growth in the near term. However, strategic pricing, patient access initiatives, and continued investment in clinical research will be crucial for maintaining its market dominance as competition intensifies.
The anticipated launch of batoclimab within the next 2-3 years is likely to contribute to market expansion by offering physicians and patients additional treatment options. Research into alternative IGF-1R inhibitors and new therapeutic approaches, including small-molecule drugs and gene therapies, could further diversify treatment options in the longer term.
As awareness of TED continues to grow among healthcare providers and patients, earlier diagnosis and intervention may become more common, potentially expanding the treatable patient population and driving further market growth for TEPEZZA and its competitors.
