Inflammation-focused Upstream set to join growing trickle of biotech IPOs

The fall flurry of biotech IPOs shows no signs of abating, with Upstream Bio becoming the latest company to express an intention to go public.

The Waltham, Massachusetts-based biotech has yet to set expectations on the size of its proposed offering, but said in a Securities and Exchange Commission filing yesterday that the proceeds would be directed toward its lead asset verekitug.

The company has pitched verekitug as the “only known antagonist currently in clinical development that targets the receptor for thymic stromal lymphopoietin (TSLP).” This cytokine is a known driver of the inflammatory response, affecting a range of immune-mediated diseases.

Proceeds from the IPO will go in part to completing an ongoing phase 2 trial of the drug in severe asthma, as well as launching a phase 3 study in the same indication. Funds will also be used to continue an ongoing phase 2 study of verekitug in chronic rhinosinusitis with nasal polyps, with plans for a phase 3 to follow. In addition, the biotech has its eye on a potential phase 2 study in COPD.

Any remaining cash will be spent on further R&D for verekitug, including expanding into other indications, as well as for working capital and general business costs, according to the filing.

The company’s recent clinical efforts have been funded by a $200 million series B last year, which saw Enavate Sciences and Venrock Healthcare Capital Partners lead a group of investors including the likes of Bain Capital Life Sciences, Wellington Management and OrbiMed. That round came just a year after the company hauled in $200 million from a series A as part of its launch in June 2022.

The Upstream story can be traced back to 2021, when lead backers OrbiMed and Maruho began building the company around verekitug, an asset won in an auction from Japanese pharma Astellas. Rather than put up a small amount to start off with, OrbiMed, Maruho and other investors provided the new biotech with significant cash to get through its initial stages.

The company began with what it described to Fierce Biotech at the time as a “lean and mean” team of 13 people, but yesterday’s filing shows that this workforce had increased to 38 full-time employees by last month.

Upstream’s C-suite also received a shake-up (PDF) in April, when Rand Sutherland, M.D., took on the CEO role after having headed up Seeker Biologics—which closed last year—and previously serving as president of Translate Bio prior to its acquisition by Sanofi.

Upstream’s intentions are the latest indication that after a summer lull, the biotech IPO scene has picked up pace, with a trio of clinical-stage companies all going public with nine-figure offerings last Friday. They were followed by the smaller-scale IPO of Kairos Pharma on Monday.