January is National Thyroid Awareness Month, a month in which the American Thyroid Association promotes campaigns to educate the public on the importance of thyroid health, as well as the prevention, treatment and cure of thyroid-related diseases.
The thyroid is a small gland located in the base of the neck. It produces the hormones triiodothyronine (T3) and thyroxine (T4) that play crucial roles in the regulation of metabolism. Abnormal production of these hormones can lead to thyroid disorders, the most common of which is hypothyroidism (underactive thyroid). Typical symptoms of hypothyroidism, which is caused by insufficient production of T4, include fatigue, weight gain, low mood and increased sensitivity to cold temperatures. Treatment usually involves hormone replacement therapy with oral levothyroxine, a synthetic version of T4.
Increasing awareness of hypothyroidism and other thyroid disorders represents an important public health strategy. Although hypothyroidism is common, it is significantly underdiagnosed. This reflects the limited awareness of thyroid function among the general public and the non-specific symptoms associated with the disease, which means that symptoms can often be attributed to other causes. Millions of Americans are currently living with undiagnosed hypothyroidism, which places them at an increased risk of complications from this condition, including cardiovascular, neurosensory and gastrointestinal diseases.
In addition to low diagnosis rates, clinical unmet needs remain in hypothyroidism as treatment with levothyroxine can often be challenging. Dosing is individualised based on factors such as age, sex, body mass and residual thyroid function, but this often requires adjustment in response to physiological changes throughout the lifetime, including ageing, weight change, pregnancy and menopause. The drug also has a narrow therapeutic index (the window of doses that are effective between those that are ineffective or produce adverse events), which means that both overdosing and underdosing of levothyroxine is common in this setting.
This highlights an unmet need for novel therapeutics. Despite this, industry investment in hypothyroidism is relatively limited. According to GlobalData’s clinical trial database, a large majority of Phase I–III clinical trials in hypothyroidism initiated over the past five years were sponsored by academic institutions, while only 14% were sponsored by pharmaceutical companies. A notable industry player within the research and development (R&D) landscape is XERIS Pharmaceuticals, which is developing XP-8121, a novel subcutaneous formulation of levothyroxine that could potentially be dosed once weekly. XP-8121 has the potential to mitigate some of the limitations associated with oral levothyroxine that can lead to suboptimal therapeutic effects, including absorption variation, which can present challenges for establishing an ideal dose. The company expects preliminary results for its Phase I trial of XP-8121 in the first quarter of this year.
Increased rates of diagnosis and treatment could, however, also spur greater R&D investment in this field by enhancing the commercial incentives for companies active within this space. This underlines the importance of campaigns that promote greater public awareness of hypothyroidism and related disorders.