Upstream Bio Shares Surge 18.27% on Strong Phase 2 Trial Data for Verekitug

Upstream Bio (UPB) shares surged 18.27% on Monday, marking a three-day rally of 21.32% and pushing the stock to its highest level since September 2025. The intraday gain reached 18.97%, driven by strong momentum following the release of pivotal clinical data.

The stock’s performance aligns with the announcement of positive Phase 2 trial results for verekitug, Upstream Bio’s lead candidate for chronic rhinosinusitis with nasal polyps (CRSwNP). The VIBRANT trial demonstrated statistically significant improvements in key endpoints, including a -1.8 reduction in nasal polyp score (p<0.0001) and a 76% decrease in the need for surgery or corticosteroids. These outcomes highlight verekitug’s potential to address a major unmet need in a disease affecting 4% of the global population.

Verekitug’s mechanism, targeting the TSLP receptor, distinguishes it from existing therapies that focus on downstream inflammatory pathways. The drug’s extended dosing interval of every 12 weeks further enhances its competitive profile. Preclinical and Phase 1 data have already established its favorable safety profile, with no serious adverse events reported in the VIBRANT trial. This positions verekitug as a candidate for regulatory readiness, with endpoints aligned to prior approvals in the CRSwNP space.

Upstream Bio is now advancing verekitug into trials for severe asthma and COPD, broadening its potential applications. The company plans to present VIBRANT data at a major medical conference, aiming to strengthen its visibility among investors and stakeholders. Management emphasized the therapy’s potential to redefine treatment standards, citing its clinical differentiation and long-term tolerability.

The stock’s recent rally reflects optimism around verekitug’s regulatory pathway and market potential. With no products currently on the market, Upstream Bio relies heavily on clinical milestones to sustain investor confidence. The trial’s success reduces dilution risks and supports a narrative of long-term growth, particularly as the company moves toward potential commercialization in a competitive respiratory therapeutics landscape.