Biotech Uncloaks Primed for 'Search and Replace' Gene Editing with $315 Million

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With its "search and replace" gene editing technology, Prime Medicine emerged from stealth mode with a massive $315 million infusion of cash to support its efforts to address the underlying genetic cause of diseases and restore normal gene function in patients with long-lasting cures.

Describing itself as a "next-generation" gene editing company, Cambridge, Mass.-based Prime Medicine likened its approach to a "DNA word processor" that has a "search and replace" function. The company's technology aims to precisely search out genetic mutations at their precise genome location, limiting concerns about toxicities or unwanted cellular changes. The company claims the technology has the potential to address more than 90% of known disease-causing mutations. 

In its announcement, Prime Medicine said its technology is exact and has been shown in laboratory models to hit the desired target with minimal or no editing in other parts of the genome. Prime Medicine said the features of its technology are capable of overcoming several technical barriers that exist with current gene-editing technologies. 

The company is advancing multiple drug discovery programs targeted at liver, eye, ex-vivo hematopoietic stem cell, and neuro-muscular indications.

Prime Medicine's "search and replace" technology, which David R. Liu and Andrew Anzalone developed, uses a prime editor protein that includes a Cas nickase domain and a reverse transcriptase domain, along with a prime editing guide RNA (pegRNA) that carries both a targeting sequence and a template for a replacement sequence. The platform searches out the specific DNA sequence in need of editing and uses the pegRNA's "replace" sequence to activate the reverse transcriptase domain. That, in turn, makes a DNA copy of the template and creates a corrected DNA sequence. The corrected sequence then preferentially replaces the original genomic DNA, resulting in a permanent edit of the DNA at the target location.

Keith Gottesdiener, chief executive officer of Prime Medicine, said its Prime Editing technology is transformative and has the potential to make a significant impact in treating diseases with an underlying genetic cause by being able to address the root of the problem. Gottesdiener, who previously helmed Rhythm Pharmaceuticals, said the company has made "great progress" in advancing its technology over the past year since the company began operating in stealth mode. 

With the $315 million from a combined Series A and Series B financing rounds, Gottesdiener said the company is operating from a position of financial strength and is driving its technology toward clinical studies in humans. He said Prime hopes that its technology "may cure or halt the progression of genetic diseases for patients."

Two years ago, while still in its early stages, Prime Medicine forged a collaboration and license agreement with Beam Therapeutics to develop prime editing technology for the "creation or correction of any single-base transition mutations, as well as for the treatment of sickle cell disease." 

The $315 million financing was supported by ARCH Venture Partners, F-Prime Capital, GV, Newpath Partners, Casdin Capital, Cormorant Asset Management, Moore Strategic Ventures, Public Sector Pension Investment Board (PSP Investments), Redmile Group, Samsara BioCapital, funds and accounts advised by T. Rowe Price Associates, Inc.

"Prime Editing represents an opportunity to do what no gene editing approach has yet been capable of – correcting nearly all types of pathogenic gene mutations, correcting multiple mutations at once, and bringing durable cures to patients across multiple disease areas, potentially with a single 'once and done' treatment approach," David Schenkein, General Partner at GV said in a statement.

In addition to developing its editing technology, Prime Medicine will use the $315 million to scale operations. The company has a goal of employing more than 100 people by the end of 2021. 


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