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Until now, most of the major breakthroughs in the CRISPR field have been led by US academics. Not anymore; Toolgen, a South Korea-based biotech company, has reported three breakthrough techniques in top-tier scientific journals.

 

The first study presents a new cell-based assay called TAgmentation of Prime Editor sequencing (TAPE-seq) that can predict genome-wide off-target candidates for prime editors (PEs). PEs are powerful tools that allow for more precise genome editing, but until now, methods for predicting off-target effects have relied on analyzing the activity of Cas9 nucleases or nickases. Toolgen’s TAPE-seq is the world’s first genome-wide off-target prediction experiment that directly uses PEs. TAPE-seq shows a lower miss rate and higher accuracy compared to existing methods and can identify valid off-target sites that were missed by other methods. The results were published in Nature Communications in December 2022.

 

The second study presents a new genome-wide off-target prediction method called Extru-seq. Until now, more than 20 genome-wide off-target prediction methods for CRISPR have been reported, which were classified as either cell-based, in vitro, or in silico. There were pros and cons for each cell-based or in vitro method. Toolgen’s Extru-seq broke the barrier between these methods by using an extruder to generate a state between cell-based and in vitro. As a result, this method combines the beneficial features of both cell-based and in vitro methods, demonstrating a high validation rate and retention of information about the intracellular environment, as well as a low miss rate. Extru-seq can be easily performed in clinically relevant cell types with little optimization. The results were published in Genome Biology in January 2023.

 

Finally, the third study presents an improved version of a high-fidelity Cas9 nuclease called Sniper2L, which has higher specificity with retained high activity. Various mutant Cas9s have been reported, which claim to show improved specificity. However, later studies have shown that there is an inverse correlation between general activity and general specificities of these mutant Cas9 proteins, which were defined as theoretical limits. Toolgen’s Sniper2L has overcome this limitation to show high specificities without losing general activities. This puts Toolgen’s patent strategies on the high ground as Toolgen can now evergreen its patent via using its biobetter Sniper2L. The results were published in Nature Chemical Biology in March 2023.

 

Jungjoon K. Lee, director and head of research of Toolgen’s platform development team, said that “Directed evolution and genome-wide off-target assessment tools are both critical technical areas for CRISPR. Toolgen proved its innovation capabilities in the recent three papers. TAPE-seq shows Toolgen’s speed as TAPE-seq is the world’s first genome-wide off-target prediction method for PEs. Extru-seq is a disruptive technology that removed the barrier between cell-based and in vitro methods. Sniper2L is an outlier that overcame the theoretical limit between general specificities and general activities of Cas9 variants. Speed, disruption, and outlier are very traits for innovation, which have mostly been monopolized by US universities until now. Now the torch has been passed to other sectors, and Toolgen, a South Korea-based biotech, has proudly joined the league of innovators for genome editing.”

The results were selected for an oral presentation (Sniper2L) and two poster presentations (Extru-seq and TAPE-seq) at the American Society of Gene & Cell Therapy (ASGCT) Conference to be held in Los Angeles from May 16-20, 2023.

 

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