Upstream Bio plunges as asthma drug misses 'home run' bar

Upstream Bio

11/02/2026 13:24

Updates

** Shares of drug developer Upstream Bio UPB.O slide 20% to $22 in premarket trading

** Company says its experimental asthma drug, Verekitug, reduced yearly asthma flare‑ups by 56% at a lower dose and 39% at a higher dose, and improved lung function in a mid‑stage study

** Truist analyst Danielle Brill says the 56% reduction is good but this "falls short of the 'home run' efficacy scenario we recently outlined"

** Side-effects were similar to earlier studies; over 90% of eligible patients entered a long‑term extension study, company says

** "There may be some initial noise in the stock given differing buy-side bogeys, we ultimately expect this outcome to drive shares higher and see upside potential of ~30% or more" Brill adds

** "Not sure this dataset dispels concerns" around emerging competition from other asthma drugs in development, Mizuho analysts notes

** UPB plans late‑stage trials in severe asthma and chronic sinus disease after talks with regulators

** Shares up ~65% in 2025

 (Reporting by Sahil Pandey and Kamal Choudhury in Bengaluru)

 ((Sahil.Pandey@thomsonreuters.com))