Upstream Bio (NASDAQ:UPB) announced breakthrough results for its lead candidate, verekitug, in a mid-stage trial that could disrupt the multibillion-dollar biologics market for severe respiratory diseases.
The Phase 2 VALIANT trial, involving 478 adults with severe asthma, met its primary endpoint by delivering a 56% reduction in the annualized asthma exacerbation rate (AAER) for patients receiving a 100 mg dose every 12 weeks.
Even with a highly extended six-month dosing schedule (400 mg every 24 weeks), the drug maintained a 39% reduction in attacks compared to placebo.
Beyond preventing flares, verekitug showed significant improvements in lung function, with FEV1 gains of up to 139 mL and substantial suppression of airway inflammation (FeNO).
The results de-risk Upstream's strategy to challenge established players like Amgen’s Tezspire.
By targeting the TSLP receptor directly rather than the cytokine itself, verekitug appears to offer comparable efficacy with significantly less frequent injections—a "differentiated profile" that management believes will drive Phase 3 success.
The company, which held $341.5 million in cash at the end of 2025, plans to advance the drug into registrational trials for both severe asthma and nasal polyps later this year.