
Animal data in hand, Nessan Bermingham banks $91.5M for Atlas-backed RNA editing play
Korro Bio, the RNA editing startup that got started on $4 million in seed funding from Atlas and some more cash from New Enterprise Associates, has brought in $91.5 million for its Series A haul.
Under executive chairman Nessan Bermingham, the biotech has racked up animal data that he said show “pretty high targeted editing straight out of the gate.” Off-target activity wasn’t an issue, and the OPERA platform appeared able to zero in on multiple types of RNA.
Now is the time to begin building the team in earnest — and pave the path to the clinic, where Bermingham hopes to arrive “well in advance of” the funding’s three-years-plus runway.
“We validated the technology, we validated the approach,” he told Endpoints News, “and now let’s take the time to be thoughtful as we think about the application from the clinical standpoint.”
That means picking a lead candidate in a target indication — he’s not ready to divulge which — that follows clear precedents in terms of clinical strategy, patient stratification and endpoints. But it is the second and third backup programs that will offer a window to the new therapeutic paradigm that OPERA opens up.

At the core of the approach is an endogenous enzyme family known as adenosine deaminase acting on RNA, or ADAR. Co-founder Josh Rosenthal elucidated the mechanism in squid and octopus through his work at the Marine Biological Laboratory, using oligonucleotide guides to recruit these enzymes to a specific site where they would convert an A to a G. That kind of change can make a world of difference for disorders like Rett syndrome, Bermingham noted.
Borrowing heavily from established research on oligonucleotides, Korro still lists the liver, eye and the central nervous system as its initial target tissues. In the CNS, in particular, a variety of players have been showing that they can go beyond the spinal cord and cortex to deeper brain regions.
Muscle, cardiovascular and other areas are also in sight down the road.
It’s a complementary tool for the genetic medicine toolbox, to use an analogy Bermingham is fond of, as the delivery system might be able to avoid the safety challenges faced by gene therapy developers such as Solid and Audentes — not to mention the cost of goods and scalability.
“I think it further exemplifies or further highlights the importance of trying to co-opt endogenous systems in cells that are already there versus having to deliver or looking to deliver much larger payloads into these cells,” he said.
There’s much work left to prove it. Having taken space at 1 Kendall Square, Korro plans to double the headcount to 40 or 50 (perhaps including a CEO) by the end of the year.
Wu Capital led the new financing alongside new investors: Qiming Venture Partners USA, Surveyor Capital, Cormorant Asset Management, MP Healthcare Venture Management and Alexandria Venture Investments.
Atlas returned for the round, as did NEA, which also invested in Shape Therapeutics — a rival RNA editing company that had its coming out party last November, one month after Korro did.
“We actually came after Shape, so they’d already committed to invest,” Bermingham said. “Being upfront about it, I think any technology and any area really does need multiple participants in there. […] We’re only better for that because no one company frankly can do it all.”