Upstream Bio to Showcase Additional Efficacy Data from the Phase 2 VIBRANT Trial of Verekitug in CRSwNP in Oral Session at EAACI 2026

Upstream Bio (Nasdaq: UPB) will present additional efficacy data from the Phase 2 VIBRANT trial of verekitug in chronic rhinosinusitis with nasal polyps (CRSwNP) at the EAACI 2026 Congress in Istanbul on June 14, 2026.

Rhea-AI Summary

Upstream Bio (Nasdaq: UPB) will present additional efficacy data from the Phase 2 VIBRANT trial of verekitug in chronic rhinosinusitis with nasal polyps (CRSwNP) at the EAACI 2026 Congress in Istanbul on June 14, 2026.

The oral session will highlight a responder analysis of clinically meaningful improvements in key disease measures. Verekitug is described as the only known TSLP receptor antagonist currently in clinical development.

Argus Jun 8 session

-8.51% close to close Open Argus

Details

News Market Reaction – UPB

In the Jun 8 session, UPB declined 8.51%, reflecting a notable negative market reaction.

Data tracked by StockTitan Argus on the day of publication.

Market Context

The stock moved -8.5% in the session following this news. A negative reaction despite additional VIB...

Analysis

The stock moved -8.5% in the session following this news. A negative reaction despite additional VIBRANT efficacy data fits a pattern where clinical news averaged a -6.86% move across five prior updates, including a -47.18% decline on positive VALIANT asthma results. The pullback may reflect broader biotech weakness and existing concerns about dilution from the $150,000,000 ATM program, even as the company reports a cash balance of $294.6 million expected to fund operations through 2027.

Key Figures

Cash & investments: $294.6 million Net loss: $40.6 million Collaboration revenue: $1.0 million +5 more

Cash & investments

$294.6 million

As of March 31, 2026; expected to fund operations through 2027

Net loss

$40.6 million

Quarter ended March 31, 2026; wider vs. $27.3M prior year

Collaboration revenue

$1.0 million

Maruho agreement revenue for quarter ended March 31, 2026

R&D expenses

$36.6 million

Quarter ended March 31, 2026; higher year over year

G&A expenses

$8.1 million

Quarter ended March 31, 2026; higher year over year

ATM program size

$150,000,000

At-the-market equity offering under sales agreement with Leerink Partners

AAER reduction

56%

Phase 2 VALIANT: 100 mg q12w severe asthma vs placebo

AAER reduction

39%

Phase 2 VALIANT: 400 mg q24w severe asthma vs placebo

Previous Clinical trial Reports

5 past events · Latest: May 18

Same Type 5 events

1. May 18

   Phase 2 data update

   24h Move

   -6.4%

   New VIBRANT data in CRSwNP with comorbid asthma showing symptom and steroid-sparing benefits.

2. Apr 17

   Conference presentation

   24h Move

   -1.1%

   Announcement of upcoming VIBRANT CRSwNP data posters at ATS 2026 focused on biomarkers and outcomes.

3. Feb 26

   Additional trial analyses

   24h Move

   +2.1%

   Plan to present additional VIBRANT efficacy and safety analyses at AAAAI 2026 late-breaking session.

4. Feb 11

   Top-line Phase 2 asthma

   24h Move

   -47.2%

   Positive VALIANT asthma results with significant AAER reductions and lung function gains for verekitug.

5. Sep 02

   Top-line Phase 2 CRSwNP

   24h Move

   +18.3%

   VIBRANT CRSwNP met primary endpoint with strong nasal polyp and symptom improvements and favorable safety.

24h Move is the share-price change in the day after each event; other market factors may also have contributed.

Key Terms

phase 2, chronic rhinosinusitis with nasal polyps, responder analysis, thymic stromal lymphopoietin, +2 more

6 terms

phase 2 medical

"additional data from its Phase 2 VIBRANT trial of verekitug in patients"

Phase 2 is the mid-stage clinical trial where a new drug or treatment is tested in a larger group of patients to see if it works and to keep checking safety after initial human testing. Think of it as a field test that proves whether a product actually delivers its promised benefit. Investors watch Phase 2 closely because its results strongly influence a medicine’s chances of reaching the market, the size of its potential sales, and the company’s valuation.

chronic rhinosinusitis with nasal polyps medical

"verekitug in patients with chronic rhinosinusitis with nasal polyps (CRSwNP)"

A long‑term inflammatory condition of the nose and sinuses that produces swollen tissue and small growths called nasal polyps, which can block airflow and reduce smell. It matters to investors because the condition is chronic, often requires ongoing medication or repeated procedures, and creates predictable demand for diagnostics, drugs and devices—similar to a recurring subscription—affecting revenue prospects and market size in respiratory and allergy-related healthcare.

responder analysis medical

"The presentation will feature a responder analysis examining the proportion"

Responder analysis is a way of measuring how many patients in a clinical study achieve a predefined, meaningful improvement—such as symptom relief or survival benchmark—rather than looking at average changes for the whole group. For investors, it highlights the proportion of people who actually benefit from a treatment, which can be more predictive of regulatory approval, market demand, and commercial value than average results; think of it as counting winners in a game instead of averaging everyone's score.

thymic stromal lymphopoietin medical

"only known antagonist of the thymic stromal lymphopoietin (TSLP) receptor currently"

Thymic stromal lymphopoietin (TSLP) is a small signaling protein the body uses like an alarm bell to alert and steer immune cells, especially in barrier tissues such as the lungs and skin. It matters to investors because drugs that block or measure TSLP can reduce allergic inflammation and other immune-driven diseases; successful therapies or tests can drive regulatory approvals, market adoption and company value much like a new product that solves a widespread problem.

tslp receptor medical

"only known antagonist of the thymic stromal lymphopoietin (TSLP) receptor currently"

A TSLP receptor is a protein on the surface of certain immune cells that binds the signaling molecule thymic stromal lymphopoietin (TSLP) and starts a chain reaction inside the cell. Think of it as a lock on a cell that the TSLP key fits into to trigger inflammation or immune activity; for investors, drugs that block or mimic this receptor can change disease outcomes and create commercial opportunities in allergy, asthma, and immune-related conditions.

biologics medical

"Transforming disease course: clinical outcomes and remission with biologics"

Biologics are medicines made from living cells or their components rather than from simple chemical recipes, more like a handcrafted product than a mass-produced pill. They matter to investors because they often command higher prices and longer patent protection but also carry greater manufacturing, regulatory and supply risks—so a successful biologic can boost a company’s revenue significantly, while setbacks can quickly affect its stock.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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WALTHAM, Mass., June 08, 2026 (GLOBE NEWSWIRE) -- Upstream Bio, Inc. (Nasdaq: UPB), a clinical-stage company developing treatments for inflammatory diseases, with an initial focus on severe respiratory disorders, today announced that additional data from its Phase 2 VIBRANT trial of verekitug in patients with chronic rhinosinusitis with nasal polyps (CRSwNP) will be presented in an oral session at the European Academy of Allergy and Clinical Immunology (EAACI) 2026 Congress in Istanbul, Turkey, on Sunday, June 14, 2026. The presentation will feature a responder analysis examining the proportion of patients who achieved clinically meaningful improvements in key measures of disease with verekitug. Verekitug is the only known antagonist of the thymic stromal lymphopoietin (TSLP) receptor currently in clinical development.

Presentation details:
Presentation Title: Verekitug, a novel TSLP receptor antagonist antibody, in participants with chronic rhinosinusitis with nasal polyps in VIBRANT: responder analysis using clinically meaningful efficacy outcome thresholds

Presenting Author: Joaquim Mullol, MD, PhD, Universitat de Barcelona

Session: OAS23 - Transforming disease course: clinical outcomes and remission with biologics

Presentation Date and Time: Sunday, June 14, 2026 – 15:15 – 16:45 TRT

Location: Room Munich

About Verekitug
Verekitug is a novel recombinant fully human immunoglobulin G1 (IgG1) monoclonal antibody that binds to the thymic stromal lymphopoietin (TSLP) receptor and inhibits proinflammatory signaling initiated by TSLP. It is the only known antagonist currently in clinical development that targets and inhibits the TSLP receptor.

TSLP is a cytokine that is a key driver of the inflammatory response in major allergic and inflammatory diseases, such as asthma, where disruption of TSLP signaling has been clinically validated as an effective therapeutic strategy. TSLP activation is one of the first events in the inflammatory cascade stimulated by allergens, viruses and other triggers, initiating the activation of downstream targets such as IL-4, IL-5, IL-13, IL-17 and IgE. Because TSLP is a target upstream in the inflammatory cascade, blocking the TSLP receptor presents an opportunity for a single treatment to impact the drivers of multiple pathological inflammatory processes across a broad set of diseases.

Verekitug has advanced into three separate global, placebo-controlled, randomized Phase 2 clinical trials including the recently completed positive VIBRANT trial (NCT06164704) in patients with CRSwNP and VALIANT trial (NCT06196879) in patients with severe asthma. The VENTURE trial (NCT06981078) in patients with moderate-to-severe chronic obstructive pulmonary disease (COPD) is ongoing. Additionally, in May 2025, Upstream Bio initiated the VALOUR trial (NCT06966479), a long-term extension study in eligible participants with severe asthma who completed the VALIANT Phase 2 clinical trial.

About Upstream Bio
Upstream Bio is a clinical-stage biotechnology company developing treatments for inflammatory diseases, with an initial focus on severe respiratory disorders. The Company is developing verekitug, the only known antagonist currently in clinical development that targets and inhibits the receptor for thymic stromal lymphopoietin (TSLP), a cytokine which is a clinically validated driver of inflammatory response positioned upstream of multiple signaling cascades that affect a variety of immune-mediated diseases. The Company has advanced this highly potent monoclonal antibody into separate Phase 2 trials for the treatment of chronic rhinosinusitis with nasal polyps (CRSwNP), severe asthma, and chronic obstructive pulmonary disease (COPD). Upstream Bio’s team is committed to maximizing verekitug’s unique attributes to address the substantial unmet needs for patients underserved by today’s standard of care. To learn more, please visit www.upstreambio.com.

Investor and Media Contact:
Meggan Buckwell
Director, Corporate Communications and Investor Relations
ir@upstreambio.com

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What is Upstream Bio (NASDAQ: UPB) presenting about verekitug at EAACI 2026?

Upstream Bio will present additional efficacy data from the Phase 2 VIBRANT trial of verekitug in CRSwNP. According to Upstream Bio, the oral session will focus on responder analyses showing proportions of patients achieving clinically meaningful improvements in key disease outcome measures.

When and where will Upstream Bio (UPB) present VIBRANT Phase 2 data at EAACI 2026?

The VIBRANT Phase 2 data on verekitug will be presented June 14, 2026, in Istanbul, Turkey. According to Upstream Bio, the session runs from 15:15 to 16:45 TRT in Room Munich during EAACI 2026’s OAS23 session.

What is the focus of the VIBRANT responder analysis of verekitug in CRSwNP?

The VIBRANT responder analysis examines patients achieving clinically meaningful improvements in key CRSwNP disease measures with verekitug. According to Upstream Bio, the analysis evaluates the proportion of participants crossing predefined efficacy thresholds considered clinically relevant for chronic rhinosinusitis with nasal polyps.

Why is verekitug noteworthy in Upstream Bio’s (UPB) CRSwNP pipeline?

Verekitug is described as the only known thymic stromal lymphopoietin (TSLP) receptor antagonist in clinical development. According to Upstream Bio, this novel antibody targets TSLP receptor activity in patients with chronic rhinosinusitis with nasal polyps enrolled in the Phase 2 VIBRANT trial.

Who will present Upstream Bio’s VIBRANT Phase 2 data on verekitug at EAACI 2026?

The VIBRANT Phase 2 verekitug data will be presented by Joaquim Mullol, MD, PhD, from Universitat de Barcelona. According to Upstream Bio, Mullol presents during EAACI 2026’s OAS23 session titled “Transforming disease course: clinical outcomes and remission with biologics.”