A handful of biotech startups have recently taken an increasingly popular route of financing: extending existing rounds rather than taking on a whole new fundraising campaign.
If “money is like oxygen for biotechs,” in the words of
Alveus
CEO Raj Kannan, funding-round top-ups are a faster, easier way to catch a quick breath.
Kannan’s Alveus is one of at least four biotechs that have bolstered their existing rounds so far this year. The obesity biotech is joined by blood-focused
Atavistik Bio
,
Xolair hunter
Poplar Therapeutics and movement disorder biotech Vima Therapeutics. Those four extensions have corralled $162 million collectively, or $552 million when factoring in the initial closes of those rounds.
Extensions can avoid the pitfalls of launching an entirely new funding round, a process that requires a longer, more intense campaign with additional diligence and dilution to existing investors. They’re especially helpful when a massive influx of capital isn’t needed to get to key data or the next value inflection point.
They are an “easy and faster way to access capital than raising a new round at new terms,” and less distracting for executives, Société Générale healthcare banker Daniel Parisotto wrote in an email. He considers them a practical solution to fix imbalances that have left many private companies “overfunded relative to public market valuations, but underfunded relative to their clinical timelines.”
About 85 biotech companies have gone this route the past two years, according to a January report from Société Générale. While the deal count stayed relatively flat from 2024 to 2025, going from 42 rounds to 43, the value of those extensions vastly rose — jumping 31% to $1.53 billion.
Jonathan Norris, a managing director of healthcare banking at HSBC, said in an email that extensions avoid potential embarrassment of valuation down-rounds, while giving the biotechs time to bolster their data. And he said there’s another scenario if a company’s results have been “off-the-charts good”: that “insiders get greedy and want the whole round for themselves ahead of a possible transaction.”
Each funding round extension has its own flavor. The motivations behind them can vary from needing more cash to get to a clinical readout, to adding top-tier investors to curry brand-name recognition for the next capital haul, or to padding out the runway to take medicines into more indications than initially planned.
Alveus first closed its Series A on Christmas week. But because there was a lot of demand in the last quarter of 2025 as biotech sentiment picked up, the company gave a 30-day deadline to investors who were already deep in due diligence, Kannan said in an interview. With that additional window, the Philadelphia and Copenhagen biotech was able to secure
fuel
from Jeito Capital and Novo Holdings. The money will fund clinical testing of a GIPR antagonist and GLP-1 agonist fusion protein, and an entry into the hotly contested amylin race.
Extensions can also free up the management team from having to focus on fundraising. In Alveus’ case, Kannan said the business chief and chief scientific officer were “both involved quite a bit” in the Series A discussions, and now with money in the bank, they can now focus on getting Alveus to clinical readouts.
Poplar
, meanwhile, did its extension last week to pad the biotech’s runway with enough money to prove whether its lead anti-IgE medicine works in food allergy and have a chance of going up against Xolair.
The company raised its initial $50 million Series A in October 2024, but didn’t come out of stealth until January, finance chief Vicki Eatwell said in an interview. They then
extended the round
last week, which will entail two tranches of $22.5 million each, the CFO said. She joined in January, reuniting with CEO Chip Baird, with whom she worked at 2seventy bio and bluebird bio.
The extension also allowed Poplar to get a few “marquee investors” with experience in the public markets, Eatwell said. The startup didn’t want to “dilute our existing investors heavily” before getting to key Phase 1 data later this year.
“We didn’t think it was fair to our existing Series A investors to take on $100 million right now in advance” of Phase 1 data, Eatwell said.
For Vima, its $40 million extension comes about 10 months after a $60 million de-stealthing for its dystonia drug. With the extra money, the startup can now test its experimental oral medicine in patients with dystonia as well as Parkinson’s patients who aren’t currently treated by dopamine-based medicines, CEO Bernard Ravina said in an interview.
The round will now get Vima through both Phase 2 studies, which will read out in the first half of 2027, Ravina said.
Vima’s new investor, Frazier, heard about the biotech’s story at Atlas Ventures’ annual retreat and “things moved very quickly from there,” Ravina said.