Upstream Bio, Inc.

What they do

Upstream Bio is developing verekitug, which it describes as the only known antagonist currently in clinical development targeting the receptor for thymic stromal lymphopoietin (TSLP), a cytokine positioned upstream of multiple inflammatory signaling cascades. The company is running separate Phase 2 trials in severe asthma (including a long-term extension), chronic rhinosinusitis with nasal polyps (CRSwNP), and chronic obstructive pulmonary disease (COPD). It is pre-commercial, with operations limited to clinical development, manufacturing and device work; its only reported revenue is $2.4M in 2023, $2.4M in 2024 and $2.9M in 2025.

Revenue drivers

• Verekitug — severe asthma — Clinical-stage monoclonal antibody in Phase 2; positive top-line Phase 2 results reported February 2026 and Phase 3 initiation planned for Q1 2027. No product revenue today.
• Verekitug — CRSwNP — Positive top-line Phase 2 results reported September 2025; Phase 3 initiation planned for Q1 2027. No product revenue today.
• Verekitug — COPD — Phase 2 VENTURE trial initiated July 2025 and enrollment completed with 481 participants; data expected in the second half of 2027. No product revenue today.
• Other revenue — Reported annual revenue was $2.4M in 2023, $2.4M in 2024 and $2.9M in 2025, with quarterly revenue of $1.0M in Q1 2026 and $773,000 in Q2 2026; the filings excerpted do not break this out by source.

Recent performance

Second quarter 2026 revenue was $773,000, down from $1.0M in Q1 2026, against quarterly revenue of $683,000 and $668,000 in the third and fourth quarters of 2025. Annual net losses widened from $20.5M in 2023 to $62.8M in 2024 and $143.4M in 2025, with operating cash use of $37.9M, $59.2M and $133.3M in those years. At June 30, 2026, total assets were $281.2M, total liabilities $10.2M, shareholder equity $271.0M and cash and equivalents $79.4M. The company completed enrollment in the Phase 2 VENTURE COPD trial with 481 participants and said End-of-Phase 2 FDA interactions for severe asthma and CRSwNP remain on track. It also reported positive Phase 2 top-line results in CRSwNP (September 2025) and severe asthma (February 2026).

Strategy

Management plans to initiate Phase 3 trials in severe asthma and CRSwNP in the first quarter of 2027, using a high-dose quarterly regimen in broad, non-biomarker-restricted patient populations. The company is conducting End-of-Phase 2 interactions with the FDA to support those Phase 3 designs, and is advancing CMC and device development toward at-home and in-office administration options. COPD remains a Phase 2 effort through the VENTURE trial, with data expected in the second half of 2027. The company states that more than 500 participants have been treated across verekitug clinical trials to date.

Risks

• No product revenue and recurring losses — Upstream Bio has no approved product and reported net losses of $143.4M in 2025 and operating cash use of $133.3M, relying on its $79.4M cash balance at June 30, 2026 to fund operations.
• Clinical and regulatory risk — Verekitug must still succeed in Phase 3 severe asthma and CRSwNP trials and in the Phase 2 VENTURE COPD trial, and the company must obtain FDA approval; earlier positive Phase 2 results may not replicate.
• Competition from tezepelumab — Tezepelumab (Tezspire, Amgen/AstraZeneca) is already FDA-approved for severe asthma without phenotype or biomarker limitation, and has advanced into Phase 3 development for COPD.
• Reliance on third parties — The company depends on third-party manufacturers to supply verekitug for clinical trials and, if approved, for commercial scale, and has not yet demonstrated commercial-scale manufacturing.

Outlook

Management says it remains on track to initiate Phase 3 trials in severe asthma and CRSwNP in the first quarter of 2027, pending ongoing End-of-Phase 2 interactions with the FDA. It expects Phase 2 VENTURE COPD data in the second half of 2027 and plans to present Phase 2 VALIANT severe asthma data at the ERS Congress in early September 2026. The company describes its goal as best-in-class efficacy with quarterly dosing across its three target indications.