SOUTH SAN FRANCISCO, Calif., April 13, 2026
Septerna, Inc. has announced the initiation of its Phase 1 clinical trial for SEP-479, a novel oral small molecule PTH1R agonist designed for the treatment of hypoparathyroidism, a rare endocrine disorder with significant unmet medical need. The milestone marks a major advancement in Septerna’s GPCR-targeted drug discovery platform, with the first participants now dosed in a randomized, placebo-controlled study evaluating safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD). The company expects to report clinical data by late 2026 or early 2027, reinforcing its commitment to accelerating innovative endocrine therapies.
Novel Oral Therapy Targeting PTH1R Pathway
SEP-479 represents a first-in-class oral therapeutic approach aimed at directly activating the parathyroid hormone receptor (PTH1R), which plays a central role in calcium homeostasis. Current standard treatments for hypoparathyroidism rely on frequent calcium supplementation or daily hormone injections, placing a substantial burden on patients. In contrast, SEP-479 is being developed as a once-daily oral therapy, offering the potential for full-day calcium control and improved patient convenience. Preclinical studies have demonstrated that SEP-479 can normalize serum calcium levels and mimic the activity of natural PTH, supporting its potential as a disease-modifying therapy. This innovative mechanism underscores Septerna’s strategy to unlock GPCR biology for next-generation therapeutics.
Phase 1 Study Design and Clinical Evaluation
The ongoing Phase 1 clinical trial is structured into single-ascending dose (SAD) and multiple-ascending dose (MAD) cohorts, enrolling up to 150 healthy adult volunteers. The study aims to generate comprehensive data on drug safety, dose response, and biological activity, with key biomarkers including serum calcium and endogenous PTH levels. The trial design reflects a rigorous clinical development framework, ensuring that SEP-479’s pharmacological profile is thoroughly evaluated before progressing into later-stage trials. The inclusion of both SAD and MAD phases enables researchers to assess both short-term and repeated dosing effects, providing critical insights into the drug’s therapeutic potential and optimal dosing strategy
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Addressing Unmet Needs in Endocrine Disorders
Hypoparathyroidism is a chronic and debilitating condition characterized by low levels of parathyroid hormone, leading to muscle cramps, fatigue, cognitive impairment, and life-threatening complications such as seizures and cardiac arrhythmias. Existing treatments often fail to fully replicate the physiological effects of PTH, leaving patients with suboptimal disease control and reduced quality of life. SEP-479’s mechanism of action aims to restore natural calcium regulation, potentially transforming the standard of care.
Septerna’s proprietary Native Complex Platform® enables the discovery of targeted oral therapies for GPCR-driven diseases, positioning the company at the forefront of precision endocrinology innovation. With a growing pipeline spanning endocrinology, immunology, and metabolic diseases, Septerna is leveraging advanced science to address high-value therapeutic areas with significant unmet need.
As the clinical development of SEP-479 progresses, the therapy holds promise to become a breakthrough oral alternative to injectable hormone treatments, offering patients greater convenience, improved compliance, and enhanced clinical outcomes. This milestone reinforces Septerna’s role as a next-generation biotech innovator, advancing transformative solutions for complex endocrine disorders and redefining treatment paradigms in hypoparathyroidism.
Source: Septerna press release
