Positive Phase 1 Results for SEPN's Oral GPCR Medicine

By Chris Stiles • Monday, March 02 11:04 • Permanent Link

Septerna, Inc. (NASDAQ: SEPN) has recently announced positive results from the phase 1 clinical trial of its oral small molecule GPCR-targeted medicine, SEP-631, designed for the treatment of mast cell-driven diseases. The results showed that SEP-631, a potent and selective oral negative allosteric modulator of mas-related G protein-coupled receptor x2 (MRGPRX2), demonstrated robust and dose-dependent inhibition of icatibant-induced skin wheal formation, with complete inhibition observed at doses as low as 10 mg once-daily.

In terms of safety and tolerability, SEP-631 was found to be well-tolerated across all doses studied, with an adverse event profile comparable to placebo. Additionally, there were no severe or serious adverse events reported, and no clinically meaningful laboratory or ECG abnormalities were observed.

The pharmacokinetic profile of SEP-631 supports convenient once-daily oral dosing, with a half-life of approximately 24 hours and no clinically meaningful effect of food on exposure, indicating dosing without food restrictions.

Moving forward, Septerna plans to advance SEP-631 into phase 2 development for chronic spontaneous urticaria (CSU) and continue evaluating additional mast cell-driven indications, such as atopic dermatitis, interstitial cystitis, migraine, and asthma.

The company is set to initiate a phase 2b clinical trial of SEP-631 in CSU in the second half of 2026. This study will be a randomized, double-blind, placebo-controlled global trial evaluating once-daily oral SEP-631 in adult patients with moderate-to-severe CSU who remain symptomatic despite treatment with second-generation antihistamines. Additionally, Septerna plans to pursue an open-label study in chronic inducible urticaria (CINDU) following the CSU study initiation.

Following the positive phase 1 results, Septerna is scheduled to host a conference call and webcast on Monday, March 2, 2026, at 8:00 a.m. ET to discuss the phase 1 results and initial phase 2 development strategy for SEP-631.

Following these announcements, the company's shares moved -4.79%, and are now trading at a price of $26.07. If you want to know more, read the company's complete 8-K report here.

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