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Septerna Announces Dosing of the First Participants in Phase 1 Clinical Trial of SEP-631, an Oral Small Molecule MRGPRX2 Negative Allosteric Modulator for the Treatment of Mast Cell-Driven Diseases
Trial Designed to Evaluate the Safety, Tolerability, Pharmacokinetics and Pharmacodynamics of SEP-631 in Healthy Volunteers SOUTH SAN FRANCISCO, Calif., Aug.
About this update from Septerna, Inc.
[{"type":"text","content":"Trial Designed to Evaluate the Safety, Tolerability, Pharmacokinetics and Pharmacodynamics of SEP-631 in Healthy Volunteers\nSOUTH SAN FRANCISCO, Calif., Aug. 21, 2025 (GLOBE NEWSWIRE) -- Septerna, Inc. (Nasdaq: SEPN), a clinical-stage biotechnology company pioneering a new era of G protein-coupled receptor (GPCR) drug discovery, today announced the dosing of the first participants in its Phase 1 clinical trial of SEP-631, a selective oral small molecule Mas-related G protein-coupled receptor X2 (MRGPRX2) negative allosteric modulator (NAM) being developed for the treatment of chronic spontaneous urticaria (CSU) and other mast cell-driven diseases. The Phase 1 single-ascending dose (SAD) and multiple-ascending dose (MAD) clinical trial will evaluate the safety, tolerability, pharmacokinetics (PK) and pharmacodynamics (PD) of SEP-631 in healthy adult volunteers. “Mast cell-driven diseases represent significant unmet medical needs worldwide, affecting millions of patients who often struggle with inadequate symptom relief with current therapies,” said Jae Kim, M.D., chief medical officer of Septerna. “We are excited to initiate the first-in-human trial for SEP-631, a small molecule NAM that aims to inhibit mast cell activation by selectively blocking MRGPRX2, a GPCR that plays a critical role in mast cell activation and degranulation. SEP-631 has the potential to provide a convenient oral treatment option for patients with CSU and other mast cell-driven diseases. As we initiate this Phase 1 trial, we look forward to further demonstrating the potential of our Native Complex Platform™ to discover new ways to modulate GPCR targets to develop novel medicines for patients in need of better treatment options.\" One of the most common mast cell-driven diseases, CSU is a systemic inflammatory skin disease characterized by the spontaneous and persistent recurrence of itchy, painful hives and angioedema. While there is no known trigger, the activation and degranulation of mast cells and release of histamine and other inflammatory mediators lead to these debilitating symptoms. While patients are initially treated with antihistamines, a significant portion do not respond to therapy, underscoring the need for new oral treatment options. Mast cells are also implicated in multiple other diseases, including asthma, atopic dermatitis, interstitial ...