Oct 10 (Reuters) - Upstream Bio, which is

developing treatments for some respiratory disorders, said on

Thursday it had raised $255 million in its initial public

offering in the United States.

The drug developer joins a swath of biotech companies

rushing towards a stock market listing as a long-awaited policy

easing cycle begins. September was the busiest month for

healthcare IPOs this year, Dealogic data showed.

Waltham, Massachusetts-based Upstream sold 15 million shares

priced at $17 apiece, within its marketed range of $15 to $17.

The IPO valued the drug developer at about $830 million.

Upstream's lead experimental drug, verekitug, is being

developed in mid-stage studies to treat severe asthma and

chronic rhinosinusitis with nasal polyps (CRSwNP), a condition

characterized by benign growths that cause pain and stuffiness.

Prior to the IPO, Upstream Bio had raised about $400 million

from investors since its inception in 2021, including a $200

million funding round last year that was led jointly by Enavate

Sciences and Venrock Healthcare Capital Partners.

The offering was underwritten by J.P. Morgan, TD Cowen,

Piper Sandler, and William Blair.

Upstream shares are expected to start trading on the Nasdaq

Global Market on Oct. 11 under the ticker symbol "UPB."

Kaiser Permanente-backed drug developer CAMP4 Therapeutics

and TPG-backed medical device maker CeriBell are also set to

start trading on Friday.