Upstream Bio (UPB) Corporate presentation summary

Company overview and strategy

• Clinical-stage immunology company developing verekitug, a potent TSLP receptor antagonist for severe respiratory diseases.

• Targeting severe asthma, CRSWNP, and COPD, with Phase 2 trials completed in asthma and CRSWNP, and ongoing in COPD.

• Plans to initiate Phase 3 trials in severe asthma and CRSWNP in Q1 2027, with regulatory engagement scheduled for later this year.

• Existing capital expected to fund operations through 2027.

• Leadership team has deep experience across biotech and pharma sectors.

Verekitug mechanism and clinical profile

• Verekitug is a fully human IgG1 antibody, uniquely antagonizing the TSLP receptor with ~300-fold greater potency than tezepelumab.

• Demonstrated robust efficacy and favorable safety in ~500 participants across five clinical studies.

• Every 12-week dosing showed strong clinical benefit in both severe asthma and CRSWNP.

• Well-characterized immunogenicity profile with no meaningful impact on safety or efficacy.

• High exposure tertiles correlated with greater clinical benefit in both indications.

Market opportunity and product positioning

• Severe asthma and COPD markets projected to exceed $35B globally by 2033, with asthma and CRSWNP representing significant commercial opportunities.

• Efficacy is the primary driver for HCPs in biologic selection; dosing convenience is valued but not at the expense of efficacy.

• Quarterly at-home dosing with a single high-dose injection is prioritized to maximize commercial value and patient convenience.

• Market research confirms most value is captured by moving to quarterly dosing, with minimal incremental benefit from less frequent dosing.