Amgen's Tepezza (teprotumumab) has received approval from Japan's Ministry of Health, Labour and Welfare (MHLW) for the treatment of active thyroid eye disease (TED) or TED with a high clinical activity score (CAS). This marks a significant advancement for patients in Japan, providing a new treatment option for this debilitating condition.
OPTIC-J Trial Results
The approval was primarily based on the results of the OPTIC-J study, a Phase 3, randomized, double-masked, placebo-controlled, parallel-group, multicenter trial conducted in Japan. The study evaluated the efficacy, tolerability, and safety of Tepezza in Japanese patients with active TED. The primary endpoint, a clinically meaningful improvement in proptosis (eye bulging), was met with high statistical significance. Specifically, 89% of patients treated with Tepezza showed an improvement in proptosis of 2 mm or more compared to only 11% in the placebo group (p<0.0001) at week 24.
Clinical Significance
Thyroid eye disease is a rare autoimmune condition that can cause a range of symptoms, including proptosis, diplopia (double vision), eye pain, redness, and swelling. It is estimated that 25,000 to 35,000 people in Japan live with TED, encompassing both active and chronic forms of the disease. Prior to the approval of Tepezza, treatment options were limited, often involving complex surgeries and high-dose steroids, which can lead to further complications.
According to Yuji Hiromatsu, MD, a professor emeritus at the Kurume University Medical Center, "People living with active TED can experience a significant burden of disease with symptoms that can make daily life difficult to navigate. The approval of TEPEZZA in Japan is an important advancement for patients and offers a new treatment option that targets the underlying mechanism of the disease."
Ongoing Research
Amgen is also conducting a separate Phase 3 clinical trial in Japan to assess the efficacy of Tepezza in patients with chronic TED and a low clinical activity score (CAS). This trial aims to expand the treatment options for a broader range of patients with TED.
Regulatory Context
Tepezza received orphan drug designation in Japan, which expedited the regulatory review process to nine months, compared to the standard 12-month review period. This designation highlights the unmet medical need for effective treatments for TED in Japan.
Global Availability
In addition to Japan, Tepezza is approved in the United States, Brazil, and the Kingdom of Saudi Arabia. Regulatory reviews are currently underway in Europe, Canada, and Australia, potentially expanding the availability of this treatment to more patients worldwide.
