Upstream Bio IPOs at $830M Valuation, Raises $255M, Advances Respiratory Treatments

Upstream Bio (Nasdaq: UPB), a Waltham, Massachusetts-based biotech startup, raised $255 million in its initial public offering (IPO), valuing the company at $830 million. Priced at $17 per share, the IPO falls within the target range of $15 to $17.

The company is targeting major respiratory conditions with its lead drug candidate, verekitug (UPB-101), which is in mid-stage trials for severe asthma and chronic rhinosinusitis with nasal polyps (CRSwNP). Verekitug is the only known antagonist in clinical development that targets the receptor for Thymic Stromal Lymphopoietin (TSLP), a cytokine that drives inflammatory responses upstream of multiple signaling cascades. This unique mechanism has the potential to provide significant relief for patients dealing with chronic respiratory inflammation.

Upstream Bio, led by CEO Rand Sutherland, MD, MPH, has advanced verekitug through several clinical trials, including a Phase 1 single-ascending dose trial, a Phase 1b multiple-ascending dose trial in asthma patients, and a Japanese ethnobridging study. Across these trials, verekitug demonstrated rapid, substantial, and sustained target engagement for up to 24 weeks after the last dose, with high subcutaneous bioavailability and no clinically meaningful immunogenicity.

The company is currently conducting two multinational, placebo-controlled Phase 2 trials for severe asthma and CRSwNP, testing dosing intervals of 12 and 24 weeks. Upstream also plans to initiate a Phase 2 clinical trial for chronic obstructive pulmonary disease (COPD) in the second half of 2025, with the goal of addressing the high unmet needs in COPD treatment.

Founded in 2021 by Oren Becker and Eran Perry, Upstream Bio has raised $400 million in funding to date, including a $200 million Series B round led by Enavate Sciences and Venrock Healthcare Capital Partners in 2023.

Upstream Bio also holds a pending patent titled 'Pharmaceutical compositions comprising anti-human TSLP receptor antibodies and methods of using the same,' covering pharmaceutical compositions that include anti-TSLP-R antibodies, buffers, excipients, and surfactants.

Upstream's shares are set to begin trading today (October 11), alongside other healthcare debuts like CAMP4 Therapeutics and CeriBell, marking momentum for the sector.

J.P. Morgan, TD Cowen, Piper Sandler, and William Blair underwrote the offering.