A few years ago, the gene editing approach at Tessera was just a “twinkle in our eye,” CEO and co-founder Geoff von Maltzahn said.

Nucleases — the crucial machinery underlying the gene editing field — do a pretty good job of cutting DNA, allowing scientists to switch off a specific gene. But von Maltzahn saw the opportunity in being able to do more.

Since launching in 2018, Tessera has created multiple platforms for what von Maltzahn calls gene writing, or the ability to write a short or long sequence into the genome autonomously and without making double strand breaks.

“Each of those three platforms is able to do things that are quite distinctive and important, and offer the potential for a whole portfolio of future clinical indications and medicines to come,” he said.

But, as the CEO says: “You gotta have fuel in the tank to go on a really big adventure.”

On Tuesday, Tessera unveiled a roughly $300 million Series C round, bringing the company’s total raise past $500 million. A global syndicate of investors dug into their wallets for this round, including the biotech’s founder Flagship Pioneering.

Also chipping in were: a subsidiary of the Abu Dhabi Investment Authority; the Alaska Permanent Fund Corporation; Altitude Life Science Ventures; ARTIS Ventures; Cormorant Asset Management; Hanwha Impact Partners; Longevity Vision Fund; March Capital; the SALT Fund; SoftBank Vision Fund 2; funds and accounts advised by T. Rowe Price Associates, and others.

The company is deploying a three-tiered platform — sans CRISPR — using mobile genetic elements in pursuit of some “really sensational medicines,” von Maltzahn said.

The category of “gene writers,” von Maltzahn said, are RNA gene writers that can rewrite the genome, changing any one base pair to another or making small insertions or deletions.

The second approach is “to give just two RNAs to human cells, and have those cells wake up the next day with a DNA gene in their genome.”

“That’s possible because the machinery that we borrowed from is able to reverse transcribe an RNA sequence into the form of DNA, and so we deliver an mRNA encoding and gene writer protein, it grabs onto the other RNA, takes it to the genome and then one letter at a time it literally writes new DNA into that location on the genome,” he said.

Those two approaches would allow scientists to make modifications to the genome with no viral vectors, opening the door for “incredible” scalability, customization and speed, the CEO explained.

The third category is what von Maltzahn calls DNA gene writers, in which they “deliver an mRNA that then codes for a protein that grabs onto the loop of DNA takes it to the genome and autonomously inserts it, and that offers the potential to allow AAVs to be cures for genetic diseases in dividing cell types like the liver,” he said.

The Series C funds will be used to “aggressively invest in the platform,” move programs toward the clinic, build up manufacturing capabilities, and expand the roughly 200-person team. The first focus will be on liver and rare genetic disease, sickle cell, and engineering CAR-T cells “both outside and inside the body.”

Von Maltzahn declined to comment on how soon those programs might reach the clinic. And when asked if he’s planning a public debut, he responded: “No plans to go public in the near future.”

“[What] financings with the splashy headlines… often miss is just how much scientific uncertainty and courage and teamwork and resolve it takes to climb these kinds of mountains,” he said. “We feel really fortunate to have the opportunity to build the company we’ve been dreaming of.”

This announcement was originally featured in Endpoints News here: https://endpts.com/flagship-founded-tessera-fuels-up-with-300m-to-go-on-a-really-big-adventure-in-gene-editing/