Respiratory biotech Upstream joins Nasdaq IPO surge

Upstream Bio has become the latest biotech to chance its arm with a public listing in the US, hoping to raise funds for inflammatory respiratory disease therapy verekitug.

The Waltham, Massachusetts-based company has advanced its TSLP inhibitor verekitug into a pair of phase 2 trials in severe asthma and chronic rhinosinusitis with nasal polyps (CRSwNP) and is also planning a mid-stage trial in chronic obstructive pulmonary disease (COPD).

It is joining the initial public offering (IPO) queue amid a flurry of IPO activity in the sector, with three biotechs listing on the Nasdaq last week – Bicara Therapeutics, Zenas BioPharma, and MBX Biosciences – while BioAge is expected to follow suit in the coming weeks.

There is a placeholder of $100 million on Upstream's IPO, according to Renaissance Capital, but the recent debuts have outperformed expectations. MBX had a similar target, but ended up raising $163 million, while Bicara and Zenas raised $315 million and $225 million, respectively.

There have been 18 biotech IPOs so far this year, roughly in line with the levels recorded in 2023 and 2022, but still a fraction of the 100-plus that made it over the line in 2021.

Verekitug has the same target as Amgen and AstraZeneca's antibody-based TSLP inhibitor Tezspire (tezepelumab), which has been approved since 2021 for severe asthma and is in clinical development for CRSwNP, eosinophilic oesophagitis, and COPD. Sales of Tezspire reached $653 million last year, fuelled by the launch of a new self-injector version.

Other potential rivals include Uniquity Bio's solrikitug, licensed from MSD, which is set to start a phase 2 trial in COPD shortly, GSK/Aiolus AIO-001 in phase 2 for asthma, and Sanofi's lunsekimig (SAR443765), a bispecific antibody that blocks both TSLP and IL-13 and is also in mid-stage testing for asthma.

In its prospectus (PDF) for the IPO, Upstream says its candidate has the potential to offer "a differentiated product profile, including improved clinical outcomes, substantially extended dosing intervals, and the potential to treat a broad spectrum of patients." It reckons its drug is the only monoclonal antibody currently in clinical development that targets and inhibits the TSLP receptor.

In phase 1b data presented at the European Respiratory Society (ERS) congress earlier this month, verekitug showed a greater effect on biomarkers of inflammation like IL-15 and IgE than have been seen with Tezspire, according to the company, and has a pharmacodynamic profile that could support dosing every 12 or 24 weeks. Amgen and AZ's drug is licensed for administration every four weeks.

Upstream plans to list on the Nasdaq under the symbol UPB. It emerged onto the scene in 2022 with a $200 million Series A round and followed that with a $200 million Series B the following year.