Korro launches to develop RNA-editing therapies

Korro Bio, a start-up that’s designing RNA-editing therapies, has launched with an undisclosed amount of funding from cofounder Atlas Venture and from New Enterprise Associates.

The start-up is based on the work of cofounder Joshua Rosenthal, a scientist at the Marine Biological Laboratory in Woods Hole, Massachusetts, who studies an enzyme called ADAR (adenosine deaminases acting on RNA). ADAR changes an adenosine to an unusual nucleoside called inosine, which protein-making machinery reads as a guanosine. Rosenthal’s group developed oligonucleotides that latch on to ADAR and direct it to a specific RNA sequence to make the nucleotide edit.

While gene-editing systems like CRISPR are designed to make permanent alterations to DNA, RNA editing is temporary. That has led some scientists and companies to cite RNA editing as a safer alternative to CRISPR. But Korro CEO Nessan Bermingham—the former CEO of the CRISPR company Intellia Therapeutics—doesn’t expect RNA editing to replace gene editing. Instead, he says, it will be used for conditions in which a permanent change to DNA would be undesirable.

Although Bermingham won’t name Korro’s lead programs, work by Rosenthal and others suggests that RNA editing could provide a way to temporarily change the production of proteins involved in cancer and inflammation by introducing a mutation that alters the protein’s function or prevents it from being made. RNA editing could also yield new, nonaddictive pain therapies by mimicking rare but naturally occurring mutations found in the sodium ion channels of people with high tolerance for pain.