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Tome Biosciences debuts with $213M and a new way to edit the genome

Dive Brief:

  • Biotechnology startup Tome Biosciences emerged from stealth on Tuesday with $213 million in venture funding to develop a new gene editing technology it believes can overcome some of the limitations of existing methods.
  • Called “programmable genomic integration,” or PGI, and based on research licensed from the Massachusetts Institute of Technology, the approach is designed to insert varying sizes of genetic material anywhere in the genome without damaging or breaking DNA. Tome will initially use it to create gene therapies for liver disorders and cell therapies for autoimmune disease, but wasn’t more specific in its announcement.
  • The $213 million comes via Series A and B rounds amassed since 2021. A lengthy list of investors contributed to the rounds, including a16z Bio + Health, Arch Venture Partners, GV and Longwood Fund. Tome is led by Rahul Kakkar, the former CEO of autoimmune drugmaker Pandion Therapeutics, which sold to Merck & Co. for $2 billion two years ago.

Dive Insight:

The recent arrival of the blood disease treatment Casgevy was a milestone for gene editing research, a field of science that’s exploded in the last decade. It is the first approved medicine based on the gene editing system known as CRISPR, and its initial clearances came only a decade after published papers described the system’s potential as a gene editing tool.

Yet scientists and a growing wave of biotechnology companies have already been working for years to improve the technology Casgevy is founded upon. For all of its impact so far, CRISPR is a somewhat blunt tool that slices through DNA’s double-stranded helix, leaving open the possibility of accidental, off-target edits and uncertainty as to the gene expression those cuts will yield. In recent years, newer methods, such as “base” and “prime” editing, have emerged as potentially more precise tools and attracted sizable investments. So, too, have approaches that make temporary or subtler changes.

Tome is pursuing what it believes to be another advance. Its approach involves a suite of technologies that can precisely insert large DNA sequences into any part of the genome. A paper co-authored by Tome’s scientific founders and published in the journal Nature last year showcased the ability of the technology the company’s built on. That paper described the potential for PGI to place sequences as large as 36,000 bases into multiple locations and cell types, all without breaking DNA. It “expands the capabilities” of gene editing, they wrote at the time.

PGI “allows us to look at DNA as if it were software and truly reprogram cells in the body to express healthy genes instead of broken ones,” Kakkar wrote in an email.

Those features may enable Tome to go after diseases other genetic medicines have a tough time targeting. Duchenne muscular dystrophy, for instance, is caused by a mutation to the largest known human gene, forcing drugmakers to develop workarounds to address it. Kakkar also claims the approach could enable the use of “safety switches” or other protective characteristics meant to boost the effectiveness or safety of cell therapies.

“CRISPR is great for breaking genes; prime and base editing are great for making small DNA changes; PGI allows us to insert any DNA sequence of any size into any programmed location,” added Chief Scientific Officer John Finn, an early employee at the gene editing company Intellia Therapeutics.

Research is in its early stages, however. Tome hasn’t named a lead candidate or said when it expects to bring a program into human testing. The company hopes to present its progress at scientific meetings next year, according to Kakkar.

“We are moving as quickly as we can,” he wrote.


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