When Fierce last caught up with OMass Therapeutics’ CEO Ros Deegan, it was hard not to be impressed by the company’s ambition.
Deegan told Fierce when the drug developer was crowned a Fierce 15 winner of 2024 that she had a goal of making the Oxford, U.K.-based startup—which at that point was still preclinical—into “Britain's Big Biotech.”
“The U.K. hasn't had a Vertex, a Genentech, a Biogen,” she pointed out, name-checking companies that pioneered the route from R&D lab to market.
Fast forward two years, and Deegan’s drive remains undimmed. Having announced an impressive $310 million series C round on Wednesday morning, the CEO described the financing as a “fantastic milestone” on the ambitious journey to “Big Biotech” status.
The company touted the raise as the second biggest of any European biotech so far in 2026, only beaten by Alphabet-founded Isomorphic Labs' $2.1 billion series B.
Like Isomorphic, OMass counts GV—the VC arm of Google’s parent company Alphabet—among its backers. The series C was co-led by Bain Capital Life Sciences, Forbion and Novo Holdings, with Janus Henderson Investors, SV Health Investors and Jefferson Life Sciences joining existing investors like Syncona, Sanofi Ventures, the U.K. government’s British Business Bank and the University of Oxford.
Having split her career across both sides of the Atlantic, Deegan told Fierce in an interview that she was “thrilled with the high-quality U.S. and European investors that are joining the syndicate.”
Top of the list of spending priorities for the series C windfall is taking OMass’ lead candidate, a melanocortin-2 (MC2) receptor antagonist dubbed OMS1620, through an ongoing phase 1 study and into phase 2 development in congenital adrenal hyperplasia (CAH) and ACTH-dependent Cushing’s syndrome.
So far, OMS1620 has only made it as far as the single-ascending dose stage of the phase 1 trial, but the company likes what it’s seen.
“Another reason that investors like this particular program is that even in the phase 1, in a healthy volunteer trial, you can do a challenge experiment with the natural hormone,” Deegan explained. “So you can get a very good read on efficacy.”
In patients with CAH, low cortisol production interrupts the normal negative feedback loop to the brain, causing the pituitary gland to overproduce adrenocorticotropic hormone (ACTH). The preclinical data Deegan's team has seen is backing up the theory that OMS1620 will be better at inhibiting high concentrations of ACTH than competitor products, as OMass’ drug is “sticky on the receptor,” she said.
“So even as those ACTH levels surge during the day, there's effectively no time for the ACTH to bind the receptor because our compound's just hanging on in there,” Deegan explained.
The biotech also has a second program in the works in the form of a preclinical SLC15A4 inhibitor, which will target lupus and other diseases associated with interferon overproduction and pathogenic B-cell activation.
When Odyssey Therapeutics went public in May, the Boston-based biotech hailed its own preclinical SLC15A4 program to modulate pathogenic B cells as a way to offer “CAR-T-like effects, but in a pill.”
OMass’ Deegan noted there’s “a lot of excitement around the target” at the moment. While early data for turning T-cell therapies like CAR-Ts towards autoimmune diseases caught the attention of the industry, Deegan pointed out that more recent readouts for these drugs have not been “quite as compelling.”
“We’ve always felt that there will be an opportunity for a new small molecule ... that can be taken potentially once a day, and more upstream in the pathway,” the CEO explained.
“What's cool about this mechanism is it's actually very similar philosophically to the MC2 mechanism, because we're going after what we think is the best node in a clinically validated pathway,” Deegan added.
In both cases, OMass' technology can trace its origins back to the University of Oxford lab of Professor Carol Robinson, Ph.D. This tech received some welcome validation last year when one of OMass' role models, Genentech, paid $20 million upfront for the license to OMass’ preclinical inflammatory bowel disease program.
Deegan said the biotech has been “very strategic” when it comes to partnering.
“How do you get a high-quality partnership, but around something where you're not actually giving away the crown jewels and reducing the potential upside?” she said.
To grow those jewels into approval-ready medicines, OMass will use part of the series C funds to “build our development capabilities … to really fill out those functions.”
“Because we're currently in phase 1, we're pretty lean from a development perspective,” Deegan explained. “But as we progress into phase 2, we’re [becoming] multi-geography.”
Having already established a presence in the U.S. back in 2024, Deegan said the financing “is going to make sure that we're able to attract the best talent on both sides of the pond.”
After ramping up the company's headcount with an eye to reading out clinical data, Deegan isn’t ruling out OMass taking its pipeline all the way to commercialization.
“My approach is always: if you can, build with your destiny in your own hands,” she said. “If you set out with your ‘Plan A’ being to build a real company, then you're going to set yourself up to make decisions … from a position of strength and only if it really moves the needle.”
So does this mean OMass has an eye on the public markets, ending the half-decade drought of IPOs for British biotechs?
“We have the capital now, so we’re not … thinking about any other kind of strategic moment,” the CEO responded.
“We're focused on progressing what we think are assets that can have a meaningful impact on patients to clinical milestones that we're now funded to deliver,” she added. “That will give us the options to make the right decisions.”
The state of biotech funding is one of the hot topics being discussed at Fierce Biotech's high-impact event in London next month. Find out more information and register by clicking on the banner below:
