Septerna (Nasdaq: SEPN) will present Phase 1 data for SEP-631, an oral MRGPRX2 negative allosteric modulator, at the 2026 AAAAI Annual Meeting in Philadelphia, Feb 27–Mar 2, 2026. The poster (L58) is scheduled for March 1, 2026, 9:45–10:45 a.m. ET in Hall E.
The presentation describes a first-in-human, proof-of-mechanism Phase 1 study using short wave infrared imaging to assess response to an icatibant skin challenge in chronic spontaneous urticaria and other mast cell-driven diseases.
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News Market Reaction – SEPN
+0.41%
+0.41%Session close to close
In the Feb 10 session, SEPN gained 0.41%, reflecting a mild positive market reaction.
This announcement highlights an upcoming Phase 1 data presentation for SEP-631, an oral MRGPRX2 nega...
Analysis
This announcement highlights an upcoming Phase 1 data presentation for SEP-631, an oral MRGPRX2 negative allosteric modulator targeting mast cell-driven diseases such as chronic spontaneous urticaria. It follows earlier milestones, including first dosing in up to 150 volunteers and the strategic shift away from SEP-786. Investors may track the 2026 AAAAI meeting (Feb 27–Mar 2) for initial human data readouts and compare them against the company’s prior disclosures of $561.6M in cash and runway into at least 2029.
Key Figures
Phase 1 volunteers:up to 150 healthy adultsAAAAI meeting dates:Feb 27–Mar 2, 2026Cash & securities:$561.6M+5 more
Discontinued SEP-786 Phase 1 after bilirubin elevations; shifting to next-gen PTH1R agonists.
24h Move is the share-price change in the day after each event; other market factors may also have contributed.
Pattern Detected
Clinical-trial headlines have produced volatile but generally directionally aligned moves, with positive SEP-631 news up and negative SEP-786 news sharply down.
Recent Company History
Recent clinical-trial news has centered on Septerna’s early pipeline. On Feb 18, 2025, the company discontinued SEP-786’s Phase 1 trial after safety findings, and the stock fell 46.99%. Later, on Aug 21, 2025, initiation of the Phase 1 trial for SEP-631 in up to 150 healthy volunteers lifted shares by 5.5%. Today’s announcement about presenting Phase 1 SEP-631 data at AAAAI ties directly into this ongoing program progression.
Key Terms
G protein-coupled receptor (GPCR), Mas-related G protein-coupled receptor X2 (MRGPRX2), negative allosteric modulator (NAM), chronic spontaneous urticaria (CSU), +4 more
8 terms
G protein-coupled receptor (GPCR)medical
"a clinical-stage biotechnology company pioneering a new era of G protein-coupled receptor (GPCR) drug discovery"
G protein-coupled receptors are a large family of proteins on the surface of cells that act like sensors or doorbells: they detect hormones, neurotransmitters and other signals outside the cell and trigger internal switch proteins to change the cell’s behavior. They matter to investors because a large portion of approved drugs and experimental medicines work by turning these sensors on or off, so discoveries, trial results or approvals involving GPCRs can significantly affect a biotech or pharmaceutical company’s value.
Mas-related G protein-coupled receptor X2 (MRGPRX2)medical
"Mas-related G protein-coupled receptor X2 (MRGPRX2) negative allosteric modulator (NAM)"
A cell-surface protein (a G protein‑coupled receptor) found mainly on immune cells called mast cells that acts like a lock for certain drugs and chemicals; when activated it can trigger rapid allergic-type reactions, inflammation, or pain. Investors care because unintended activation by a drug candidate can cause safety problems, regulatory setbacks or additional development costs, while deliberately targeting it can create new therapeutic opportunities—think of it as a safety switch or potential drug target.
negative allosteric modulator (NAM)medical
"MRGPRX2) negative allosteric modulator (NAM) being developed for the treatment"
A negative allosteric modulator (NAM) is a drug that attaches to a different spot on a cell’s receptor than the normal activating molecule and reduces the receptor’s activity — like turning down the volume on a radio without changing the station. For investors, NAMs matter because they can offer more precise control of a drug’s effects, potentially improving safety, dosing and competitive differentiation, which influences development costs, approval prospects and commercial value.
chronic spontaneous urticaria (CSU)medical
"developed for the treatment of chronic spontaneous urticaria (CSU) and other mast cell-driven diseases"
Chronic spontaneous urticaria (CSU) is a disease in which red, itchy hives or swollen welts recur for six weeks or more without a clear trigger, often flaring unpredictably and lasting months to years. For investors, CSU represents a defined and persistent patient population where new drugs, regulatory approvals, trial results, or changes in coverage can meaningfully affect treatment demand and a company’s revenue outlook—like a market reshaped by a reliable, long‑term product.
mast cell-driven diseasesmedical
"for the treatment of chronic spontaneous urticaria (CSU) and other mast cell-driven diseases"
A group of conditions caused when mast cells — a type of immune cell that helps defend the body — activate inappropriately and release chemicals that produce chronic allergy, inflammation or other systemic symptoms. Think of mast cells as fire alarms that sometimes trigger sprinklers for no fire; that misfiring drives persistent illness and health-care demand. For investors, these diseases represent targets for drug development, clinical trials and regulatory milestones that can create significant market opportunities or reshape treatment landscapes.
Phase 1 clinical trialmedical
"present data from its Phase 1 clinical trial of SEP-631 at the 2026 American"
A phase 1 clinical trial is the first stage of testing a new drug or treatment in people, typically involving a small group to assess safety, how the body handles the treatment, and appropriate dosing. For investors, phase 1 results are an early risk check — like a test drive that can reveal fatal flaws or promising signals — and they often cause big changes in a drug’s perceived value and the company’s prospects.
short wave infrared imagingmedical
"Utilizing Short Wave Infrared Imaging to Assess Response to an Icatibant Skin Challenge"
Short wave infrared (SWIR) imaging is a camera technology that captures light just beyond the visible spectrum, revealing details about materials, moisture, and temperature that ordinary cameras miss. Think of it as a special pair of glasses that lets you see hidden differences in objects and scenes, which matters to investors because it powers higher-value products and services (in manufacturing, agriculture, defense, and medical devices), can improve quality control and safety, and thus creates potential revenue and competitive advantage for companies developing or using the sensors.
icatibantmedical
"Infrared Imaging to Assess Response to an Icatibant Skin Challenge"
Icatibant is a prescription drug given by injection that blocks the action of a chemical (bradykinin) that causes sudden, severe swelling in people with hereditary angioedema. It acts quickly to relieve acute attacks and is used on demand rather than as a daily medicine. For investors, icatibant matters because its clinical effectiveness, regulatory approval, pricing and patient access directly influence a maker’s sales potential and competitive position in a niche, recurring-care market.
SOUTH SAN FRANCISCO, Calif., Feb. 10, 2026 (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 that the company will present data from its Phase 1 clinical trial of SEP-631 at the 2026 American Academy of Allergy Asthma & Immunology (AAAAI) Annual Meeting, taking place February 27-March 2, 2026, in Philadelphia. SEP-631 is 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.
Poster Presentation Details:
Title: First-In-Human, Proof-of-Mechanism Phase 1 Study of the Oral MRGPRX2 Antagonist SEP-631 Utilizing Short Wave Infrared Imaging to Assess Response to an Icatibant Skin Challenge Poster Number: L58 Session: Late Breaking Poster Session II Session Date and Time: March 1, 2026, 9:45-10:45 a.m. ET Location: Pennsylvania Convention Center, Level 2, Hall E
About SEP-631 Septerna is developing SEP-631, a selective oral small molecule Mas-related G protein-coupled receptor X2 (MRGPRX2) negative allosteric modulator (NAM) for the treatment of patients with chronic spontaneous urticaria (CSU) and other mast-cell driven diseases. MRGPRX2 is known to play an important role in mast cell activation and degranulation which, in combination with other inflammatory mediators, lead to debilitating symptoms for patients. In addition to CSU, MRGPRX2 is highly and uniquely expressed on mast cells implicated in multiple diseases, including asthma, atopic dermatitis, interstitial cystitis, and migraine. In preclinical studies, SEP-631 demonstrated potent and long-lasting inhibition of MRGPRX2 and blocked mediator-induced skin extravasation in mice engineered to express the human MRGPRX2 receptor.
About Septerna Septerna, Inc. is a clinical-stage biotechnology company with a world-class team of GPCR experts and drug developers advancing cutting-edge science to unlock the full potential of GPCR therapies for patients with significant unmet needs. The company’s proprietary Native Complex Platform™ is designed to enable new approaches to GPCR drug discovery and has led to the development of a diverse pipeline of novel oral small molecule drug candidates. Septerna is advancing programs in endocrinology, immunology and inflammation, metabolic diseases and additional therapeutic areas, both independently and with partners. For more information, please visit www.septerna.com.
What Phase 1 SEP-631 data will Septerna (SEPN) present at AAAAI 2026?
Septerna will present first-in-human, proof-of-mechanism Phase 1 data for SEP-631 on March 1, 2026. According to Septerna, the poster describes use of short wave infrared imaging to assess responses to an icatibant skin challenge in mast cell-driven diseases.
When and where is Septerna's (SEPN) SEP-631 poster session at the 2026 AAAAI meeting?
The SEP-631 poster (Number L58) is scheduled for March 1, 2026, 9:45–10:45 a.m. ET at the Pennsylvania Convention Center, Level 2, Hall E. According to Septerna, it will appear in Late Breaking Poster Session II.
What is SEP-631 and which conditions is Septerna (SEPN) developing it to treat?
SEP-631 is a selective oral MRGPRX2 negative allosteric modulator under development for chronic spontaneous urticaria and other mast cell-driven diseases. According to Septerna, the program targets MRGPRX2-mediated mast cell activation pathways.
How did Septerna (SEPN) assess pharmacologic effect in the SEP-631 Phase 1 study?
The Phase 1 study used short wave infrared imaging to measure response to an icatibant skin challenge as a proof-of-mechanism. According to Septerna, this imaging approach was applied to quantify SEP-631 effects on mast cell-driven skin responses.
Will Septerna (SEPN) provide clinical readouts or timelines for SEP-631 commercialization at AAAAI 2026?
The AAAAI poster presents early Phase 1 proof-of-mechanism data and does not announce commercialization timelines. According to Septerna, the presentation focuses on first-in-human results and imaging-based assessment rather than regulatory or commercial milestones.
