Announcement • May 20

Upstream Bio, Inc. Presents New Data from Phase 2 Vibrant Trial of Verekitug Demonstrating Improvement in Asthma Symptom Control in Participants with CRSwNP and Comorbid Asthma

Upstream Bio, Inc. presented new data from the Phase 2 VIBRANT trial evaluating verekitug in participants with chronic rhinosinusitis with nasal polyps (CRSwNP). The data, presented in two posters at the American Thoracic Society 2026 International Conference in Orlando, FL, demonstrated the positive effect of verekitug in participants with CRSwNP and comorbid asthma, as well as its impact on type 2 inflammatory biomarkers in blood and nasal secretions. Approximately 60% of the 81 participants in the VIBRANT trial had comorbid asthma. Among participants with comorbid asthma, verekitug 100 mg administered every 12 weeks led to improvement in asthma symptom control at Week 24, with a placebo-adjusted least squares mean reduction in ACQ-6 of -0.9 (95% CI: -1.6 to -0.2; nominal p=0.014) compared with placebo—well above the minimal clinically important change in ACQ-6 of -0.5. Verekitug also led to improvements in NPS at Week 24 in participants with and without comorbid asthma, consistent with the previously reported VIBRANT top-line results. In participants with comorbid asthma, generally greater improvements were observed across sinonasal symptom measures, including nasal congestion score (NCS), total symptom score (TSS), difficulty with sense of smell (DSS), and Lund-Mackay score, compared with participants without comorbid asthma. Among participants with comorbid asthma, verekitug reduced the need for rescue systemic corticosteroids or CRSwNP surgery by 83% (nominal p=0.027) compared with placebo. In a separate post hoc analysis, verekitug 100 mg administered every 12 weeks led to rapid and sustained reductions in key type 2 inflammatory cytokines, including IL-4, IL-5, and IL-13, in both blood and nasal secretions over 24 weeks of treatment with generally greater reductions observed in nasal secretions. Verekitug also reduced additional mediators of local inflammation and fibrotic activity, including periostin, thymus and activation-regulated cytokine (TARC), macrophage-derived chemokine (MDC), and eotaxin-3, shedding light on the mechanisms by which a thymic stromal lymphopoietin (TSLP) receptor blockade may benefit patients with inflammatory airway disease. Verekitug reduced blood eosinophils by 50% as early as Week 2, with reductions sustained through Week 24. Reductions in IgE were observed beginning at Week 4 and continued to decline through Week 24. The magnitude of IL-5 reduction in blood correlated with the magnitude of reduction in blood eosinophils following verekitug treatment (Pearson r=0.68). VIBRANT (NCT06164704) was a Phase 2 global, randomized, double-blind, placebo-controlled, parallel group clinical trial that evaluated the efficacy and safety of verekitug over 24 weeks in 81 adults with CRSwNP. Upstream Bio designed the VIBRANT trial using endpoints that, pending interactions with regulatory authorities, could produce data to support submissions for product approval. The Company plans to initiate dosing in Phase 3 registrational trials in both CRSwNP and severe asthma in the first quarter of 2027. The Phase 2 VIBRANT trial (NCT06164704) was a global, randomized, placebo-controlled, parallel group clinical trial, which was designed to assess the efficacy and safety of verekitug in adults with CRSwNP who were receiving concurrent intranasal corticosteroid therapy. Participants received either 100 mg of verekitug or placebo subcutaneously every 12 weeks for 24 weeks. The primary endpoint was change in endoscopic nasal polyp score at Week 24, a primary endpoint that has been used in several registrational trials for other biologic treatments for CRSwNP. Secondary endpoints included: nasal congestion score, sinus opacification, difficulty with sense of smell, total symptom score, percentage of participants requiring systemic corticosteroids or nasal polyp surgery, and time to first such interventions up to Week 24. 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 positive VIBRANT trial (NCT06164704) in patients with CRSwNP and the positive 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.

Announcement • Sep 30

Upstream Bio, Inc. Presents Data Showing Structural and Mechanistic Drivers of Verekitug's Potent Pharmacodynamic Activity and Differentiated Clinical Profile at European Respiratory Society Congress

Upstream Bio, Inc. presented structural and mechanistic data showing verekitug's potent pharmacodynamic activity through its unique approach of targeting the thymic stromal lymphopoietin (TSLP) receptor. Data were presented at the European Respiratory Society (ERS) Congress being held September 27 - October 1, 2025, in Amsterdam, Netherlands. Preclinical and clinical data to date demonstrate verekitug's highly potent inhibition of the TSLP receptor. In clinical trials, verekitug has demonstrated rapid, substantial, and sustained TSLP receptor inhibition for up to 24 weeks after the last dose. Verekitug has advanced into three separate global, placebo-controlled, randomized Phase 2 clinical trials including the recently completed VIBrant trial (NCT06164704) in patients with chronic rhinosinusitis with nasal polyps (CRSwNP), which demonstrated that verekitug, dosed at 100 mg once every 12 weeks, met both the primary and secondary endpoints at Week 24 and was generally well tolerated. Two additional ongoing clinical trials include the VALIANT trial (NCT06196879) in patients with severe asthma and the VENTURE trial (NCT06981078) in patients with moderate-to-severe chronic obstructive pulmonary disease (COPD). 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. Three Phase 1 clinical trials have been completed for verekitug, including a Phase 1 single-ascending dose (SAD) clinical trial and a Phase 1b multiple-ascending dose (MAD) clinical trial. These statements may be identified by words such as "aims," "anticipates," "continue," "continue," "could," "estimates," "forecasts," " goal," "intends," "plans," "possible," "predict," "project," "seeks," "should, "target," "will" and variations of these words or similar expressions. These forward-looking statements include, without limitation, express or implied statements regarding: the clinical development of verekitug for the treatment of severe asthma, CRSwNP and COPD, including the initiation, timing, progress and results of ongoing and planned clinical trials; expectations for future discussions with regulatory authorities and the potential of the endpoints of the Company's clinical trials to produce data that could support submissions for product approval; expectations regarding the differentiation, safety, efficacy or tolerability of verekitug; expectations regarding the translation of PK/PD modeling data of verekitug to clinical effects; and assessments compari ng non-head-to-head clinical data of vere kitug to published data fortezepelumab. Readers are cautioned that actual results, levels of activity, safety, efficacy, performance or events and circumstances could differ materially from those expressed or implied in the Company's forward-looking statements due to a variety of risks, risks, and risks, and risks, risks, risks, risks, and risks and risks, risks, and risks of the Company's forward-looking statement due to a variety of risks.

Interest coverage ratio	n/a
Cash	US$294.58m
Equity	US$304.00m
Total liabilities	US$14.06m
Total assets	US$318.05m

Data	Last Updated (UTC time)
Company Analysis	2026/06/14 05:43
End of Day Share Price	2026/06/12 00:00
Earnings	2026/03/31
Annual Earnings	2025/12/31

Package	Data	Timeframe	Example US Source ^*
Company Financials	10 years	Income statement Cash flow statement Balance sheet	SEC Form 10-K SEC Form 10-Q
Analyst Consensus Estimates	+3 years	Forecast financials Analyst price targets	Analyst Research Reports Blue Matrix
Market Prices	30 years	Stock prices Dividends, Splits and Actions	ICE Market Data SEC Form S-1
Ownership	10 years	Top shareholders Insider trading	SEC Form 4 SEC Form 13D
Management	10 years	Leadership team Board of directors	SEC Form 10-K SEC Form DEF 14A
Key Developments	10 years	Company announcements	SEC Form 8-K

Analyst	Institution
Cory Kasimov	Evercore ISI
Matthew Caufield	H.C. Wainwright & Co.
Tessa Romero	J.P. Morgan

Upstream Bio Balance Sheet Health

Financial Health criteria checks 6/6

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Recent financial health updates

Will Upstream Bio (NASDAQ:UPB) Spend Its Cash Wisely?

Upstream Bio (NASDAQ:UPB) Is In A Good Position To Deliver On Growth Plans

We Think Upstream Bio (NASDAQ:UPB) Can Afford To Drive Business Growth

Recent updates

Price target decreased by 12% to US$38.25

Will Upstream Bio (NASDAQ:UPB) Spend Its Cash Wisely?

Upstream Bio: The Reset Is The Opportunity, Initiating At Buy

Consensus revenue estimates increase by 51%

Upstream Bio, Inc. Presents New Data from Phase 2 Vibrant Trial of Verekitug Demonstrating Improvement in Asthma Symptom Control in Participants with CRSwNP and Comorbid Asthma

First quarter 2026 earnings: EPS in line with analyst expectations despite revenue beat

Upstream Bio, Inc., Annual General Meeting, Jun 09, 2026

Price target decreased by 11% to US$44.14

Full year 2025 earnings: Revenues exceed analysts expectations while EPS lags behind

Upstream Bio, Inc. has filed a Follow-on Equity Offering in the amount of $150 million.

Upstream Bio, Inc. to Present Additional Analyses from Phase 2 Vibrant Trial in Chronic Rhinosinusitis with Nasal Polyps in Late-Breaking Session At AAAAI Annual Meeting 2026

New major risk - Share price stability

Upstream Bio, Inc. Reports Positive Top-Line Results from the Phase 2 Valiant Trial of Verekitug for the Treatment of Severe Asthma

New major risk - Revenue and earnings growth

Third quarter 2025 earnings: EPS and revenues exceed analyst expectations

Upstream Bio, Inc. Presents Data Showing Structural and Mechanistic Drivers of Verekitug's Potent Pharmacodynamic Activity and Differentiated Clinical Profile at European Respiratory Society Congress

New minor risk - Share price stability

Upstream Bio, Inc. Reports Positive Top-Line Results from the Phase 2 Vibrant Trial of Verekitug for the Treatment of Chronic Rhinosinusitis with Nasal Polyps (CRSwNP)

Upstream Bio (NASDAQ:UPB) Is In A Good Position To Deliver On Growth Plans

New major risk - Revenue and earnings growth

Upstream Bio, Inc. Announces First Patient Dosed in Phase 2 Clinical Trial of Verekitug in Chronic Obstructive Pulmonary Disease (COPD)

Upstream Bio, Inc.(NasdaqGS:UPB) dropped from Russell 3000E Growth Index

First quarter 2025 earnings released: US$0.51 loss per share (vs US$4.68 loss in 1Q 2024)

Upstream Bio, Inc., Annual General Meeting, Jun 10, 2025

Upstream Bio: Verekitug, A Longer-Acting Dupixent? - Key Data Is Imminent

We Think Upstream Bio (NASDAQ:UPB) Can Afford To Drive Business Growth

Full year 2024 earnings: EPS and revenues exceed analyst expectations

Upstream Bio: Treating Respiratory Disorders With TSLP Targeting Differentiation

Upstream Bio: Attractive, But Let's Wait For More Data And Lock-Up Expiry

Third quarter 2024 earnings: Revenues exceed analysts expectations while EPS lags behind

Upstream Bio, Inc. has completed an IPO in the amount of $255 million.

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