Upstream Bio — Third Quarter 2026 Earnings Summary

Financial Performance:

• Cash, cash equivalents, and short-term investments totaled $207.4 million as of September 30, 2026, expected to fund operations through 2027.
• Research and development expenses were $36.6 million for the quarter ended September 30, 2026, an increase from $33.0 million in the same period in 2025, driven by higher personnel-related expenses (including share-based compensation) and clinical costs.
• General and administrative expenses were $7.2 million for the quarter ended September 30, 2026, an increase from $5.5 million in the same period in 2025, driven by higher personnel-related expenses and professional fees.
• Net loss was $41.2 million for the quarter ended September 30, 2026, compared to a net loss of $33.7 million for the same period in 2025.
• Collaboration revenue was $0.395 million for the quarter ended September 30, 2026, down from $0.683 million in the same period in 2025.
• For the nine months ended September 30, 2026, total operating expenses were $131.6 million compared to $116.4 million in the prior year period.
• Net loss for the nine months ended September 30, 2026, was $121.5 million compared to $101.0 million in the prior year period.
• Total assets were $246.0 million as of September 30, 2026, down from $353.8 million as of December 31, 2025.
• Accumulated deficit increased to $455.7 million as of September 30, 2026, from $334.2 million as of December 31, 2025.

Guidance and Future Outlook:

• The company plans to initiate Phase 3 trials for verekitug in severe asthma and chronic rhinosinusitis with nasal polyps (CRSwNP) in the first quarter of 2027.
• Preparations for the Phase 3 trial initiations are underway, with key clinical, regulatory, and manufacturing milestones achieved.
• Data from the Phase 2 VENTURE trial in COPD and the Phase 2 VALOUR long-term extension study in severe asthma are expected in the second half of 2027.
• Management expects operating expenses and capital expenditure requirements to support maturation into a late clinical-stage company.

Business Segments and Product Lines:

• Verekitug is the only known antagonist in clinical development targeting and inhibiting the thymic stromal lymphopoietin (TSLP) receptor.
• The Phase 2 VENTURE trial in COPD is ongoing with approximately 480 participants enrolled; it is a global, randomized, double-blind, placebo-controlled trial assessing efficacy and safety across 12 and 24-week dosing intervals with a primary endpoint of annualized COPD exacerbation rates.
• Enrollment for the VENTURE trial was completed in August 2026.
• The Phase 2 VALOUR long-term extension study in severe asthma is ongoing with more than 90% retention of eligible participants from the Phase 2 VALIANT study.
• More than 500 participants have been treated with verekitug across clinical development programs to date.
• Positive Phase 2 results have been generated for verekitug in CRSwNP and severe asthma.

Market and Competitive Landscape:

• Verekitug targets severe inflammatory respiratory diseases including severe asthma, CRSwNP, and COPD, areas with significant unmet medical need.
• The company positions verekitug as having the potential to deliver best-in-class efficacy and convenient quarterly at-home dosing, aiming to redefine treatment expectations and establish a new standard of care.
• Verekitug's mechanism targets TSLP, a cytokine positioned upstream of multiple inflammatory pathways.

Risks and Challenges:

• Risks include the ability to advance verekitug through clinical development and obtain regulatory approval on the expected timeline.
• Clinical study results may not be predictive of future results.
• The company faces dependence on third parties for clinical trials, manufacturing, and potential commercialization.
• There is a risk regarding the ability to attract, hire, and retain key personnel and protect intellectual property.
• The company may require substantial additional funds to complete development activities and commercialize verekitug.
• Regulatory approval processes and competitive industry dynamics present uncertainties.

Management Commentary and Tone:

• CEO Rand Sutherland, MD, stated the team is focused on the timely execution of startup activities for Phase 3 trials.
• Management expressed confidence that verekitug has the potential to make a meaningful difference for patients based on substantial and consistent clinical evidence.
• The tone emphasizes advancing verekitug in diseases with unmet medical need where its efficacy profile and dosing convenience offer opportunities to establish a new standard of care.

Other Key Points:

• Upstream Bio will participate in the Truist Securities 2026 Biopharma Symposium (November 12), the 9th Annual Evercore Healthcare Conference (November 30–December 2), and the 38th Annual Piper Sandler Healthcare Conference (December 1–3).
• The company intends to use its investor relations website to disclose material nonpublic information in compliance with Regulation FD.
• The press release includes forward-looking statements regarding clinical development, regulatory interactions, and financial expectations, subject to risks and uncertainties.