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Upstream Bio, a richly funded startup, reveals its lead drug and research plans

An inflammatory disease drug cast aside by Astellas Pharma has a new owner in Upstream Bio, an emerging biotechnology startup led by industry veteran Samantha Truex and backed by $200 million in venture financing.

Upstream, which has been operating in stealth since forming last year, will build on initial research conducted by Astellas and initially develop the drug for asthma. The investors behind Upstream bought the experimental medicine from the Japanese pharmaceutical company at an auction in October, when they also closed the startup’s Series A financing.

Upstream officially launched publicly Thursday, announcing its development plans, as well as the appointment of former Biogen executive Aaron Deykin as chief medical officer and head of R&D. Endpoints News previously, reported Upstream’s formation.

Upstream is an atypical startup as it’s built around a drug candidate that’s already been through preclinical testing and into early human study. The antibody-based treatment, now called UBP-101, targets a protein that influences the body’s inflammatory response to triggers like allergens or viruses. Called TSLP for short, the protein signals others that also play a role in inflammation.

And unlike most other startups whose first challenge is proving their science, Upstream can point to Amgen and AstraZeneca’s recently approved asthma medicine Tezspire, which also targets TSLP.

According to Truex, the company believes UBP-101 can separate itself from Tezspire in asthma and in other inflammatory diseases. “We have hypotheses about differences we can provide, and we’ll be testing those in the clinic,” the CEO said in an interview. One difference is how UBP-101 works, binding to the TSLP receptor rather than the associated ligand, or protein.

Truex has a background in inflammatory and autoimmune diseases, having served as CEO at Quench Bio and as chief business officer at Padlock Therapeutics, a startup Bristol Myers Squibb acquired in 2016, before that. After winding down Quench in 2021, Truex joined Atlas Venture as a venture partner.

Truex said she was searching for an asset to build her next company around when Upstream’s investors reached out, offering what she described as an opportunity she couldn’t turn down.