Windward Bio is sailing toward the public markets with the aim of wafting in over $200 million in proceeds to fund two respiratory drugs licensed from China.
The Swiss biotech already outlined an intention to list on the Nasdaq, and on Monday the company said it was planning to offer 10.3 million shares priced between $16 and $18 apiece. Assuming the final price falls in the middle of this range, Windward expects to take $203.8 million in net proceeds—rising to $228 million if underwriters fully take up their offer to buy an additional 1.5 million shares, according to a Monday filing.
Top of the list of spending priorities is WIN378, an anti-human thymic stromal lymphopoietin (TSLP) monoclonal antibody that Windward acquired from Kelun-Biotech and Harbour BioMed in a $970 million biobucks deal last year. Since then, the biotech has taken the candidate into a phase 2 trial in chronic obstructive pulmonary disease (COPD) and a phase 2/3 trial in asthma.
Windward reckons it will need up to $227.5 million to complete these studies, as well as kick off a phase 3 trial in asthma, which is due to launch in the first half of next year.
TSLP has become a hot target in immunology, acting as an upstream master switch for the inflammatory cascade. Amgen and AstraZeneca broke into the field in 2021 with the FDA’s approval for the injection Tezspire as an add-on maintenance treatment of severe asthma.
More recently, Upstream Bio’s verekitug has shown Tezspire-like efficacy in asthma, although a 24-week dose—which would be a more direct competitor to Windward’s WIN378—fell short of expectations.
GSK entered the arena in 2024 through its $1 billion upfront deal to acquire Aiolos Bio, which got its long-acting anti-TSLP antibody from China’s Hengrui Pharmaceuticals. Other companies, such as Teva and Blackstone-backed Uniquity Bio, are also in the mix with their own anti-TSLP candidates.
Windward has another bet on TSLP in the form of WIN027, which targets both TSLP and human interleukin-13 (IL-13). The biotech is betting that this dual targeting has the “potential to deliver deeper and more durable disease control than targeting either pathway alone,” it explained in the filing.
Sanofi’s TSLP and IL-13 inhibitor aced a pair of mid-stage studies for respiratory diseases earlier this year, but missed on a phase 2 eczema trial.
Windward reckons it may need up to $85 million to run a planned phase 2b study of WIN027 in COPD and launch a phase 2 trial in atopic dermatitis. Windward also acquired that asset from China last year, penning a $700 million deal with Qyuns Therapeutics for the IgG1 bispecific monoclonal antibody.
Then there’s between $5 million and $10 million that could be used to advance the company’s preclinical bispecific programs. These are headed up by a next-gen bispecific targeting both type 2 (T2) and non-T2 inflammatory pathways.
The Basel-based biotech is headed up by CEO Luca Santarelli, M.D., who previously ran VectivBio and Therachon. VectivBio was bought by Ironwood Pharmaceuticals, while Therachon was acquired by Pfizer.
Windward hasn’t had any problems bringing in funds in the past, having secured a $200 million series A in 2025 backed by the likes of Novo Holdings. The company followed that up with a $165 million series B earlier this year—which saw Sanofi’s VC arm hop aboard—and still had $207.3 million in cash, cash equivalents and marketable securities at the end of June.
Alongside the IPO, Sanofi has agreed to purchase $50 million of Windward’s stock in a private placement, the biotech disclosed in the filing.
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