RARE Daily

Prime Medicine Launches with $315 Million to Deliver on the Promise of Prime Editing

July 13, 2021

Prime Medicine, a company that promises to deliver on prime editing technology to provide lifelong cures to patients, officially launched with $315 million in financing.

The financing comprised $115 million in series A, and based on the rapid progress of its science, another $200 million series B financing approximately nine months after the company began operations. ARCH Venture Partners, F-Prime Capital, GV, and Newpath Partners financed the series A, and all participated in the series B round. The Series B also included new investors Casdin Capital, Cormorant Asset Management, Moore Strategic Ventures, Public Sector Pension Investment Board, Redmile Group, Samsara BioCapital, funds and accounts advised by T. Rowe Price Associates, and a number of additional, unnamed life sciences investment funds.

“Prime Editing is a wonderful example of the revolution in genetic medicine that we are living through,” said Robert Nelsen, co-founder and managing director of ARCH Venture Partners. “When mature, gene editing technologies like this could totally change our conception of what’s possible in treating disease.”

The funds raised will be used to continue building the company, rapidly advance towards clinical indications, expand the capabilities of the platform, and to further enhance the promise of prime editing. By the end of 2021, Prime Medicine expects to employ more than 100 people full-time.

Prime Medicine came on the scene in late 2019 when it entered into a collaboration with Beam Therapeutics to advance the development of its gene editing technology, called prime editing. Under that agreement, Beam got the exclusive right 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, both of which Beam was already pursuing with its base editing technology. Transition mutations (for example A to G, C to T) are the largest single class of disease-associated genetic mutations and are also potentially treatable with base editing.

Prime editing was developed by scientific founders David Liu, a co-founder of Beam Therapeutics, and Andrew Anzalone, at the Broad Institute of MIT and Harvard. Anzalone conceived of prime editing and brought it to Liu’s laboratory, where it was developed. Anzalone is now advancing prime editing as head of Prime Editing Platform at Prime Medicine.

Prime Editing is a next-generation gene editing technology that acts like a DNA word processor to “search and replace” disease-causing genetic sequences at their precise location in the genome, without resulting in double-strand DNA breaks that cause unwanted cellular changes. It is versatile, with the potential to address more than 90 percent of known disease-causing mutations and works in a variety of dividing and non-dividing primary human cells, as well as in animals. Prime editing has been shown by multiple independent laboratories to make genome edits with high fidelity, making edits precisely at the desired location with minimal or no editing in other parts of the genome. Together, these features overcome several technical barriers attributed to earlier gene editing technologies.

“Prime Editing is a transformative technology that we believe will make a significant impact by addressing the fundamental causes of genetic disease,” said Keith Gottesdiener, CEO of Prime Medicine. “Since Prime began operations in the summer of 2020, we have continued to make great progress in advancing the performance of prime editing, which allowed us to close our series B financing nine months later. We are operating from a position of financial strength and look forward to further developing the technology and progressing our preclinical programs toward the clinic, with the hope that they may cure or halt the progression of genetic diseases for patients.”

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

A study describing Prime Editing’s ability to “search and replace” to restore normal genetic function almost anywhere in the genome was first published in Nature in 2019. The technology was immediately and widely recognized as a major advance in gene editing, with the potential to overcome fundamental barriers that have prohibited existing gene editing approaches from addressing many genetic diseases. Since then, Prime Editing has been validated in numerous laboratories around the world and dozens of peer-reviewed articles.

The technology works by using a prime editor protein comprising a Cas nickase domain and a reverse transcriptase domain, together with a prime editing guide RNA (pegRNA) that carries both a targeting sequence and a template for a replacement sequence. The prime editor searches for the specific DNA sequence that needs to be edited. Once located, the prime editor uses the pegRNA’s “replace” sequence to activate the reverse transcriptase domain, which makes a DNA copy of the template carried by the pegRNA, creating 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.

Prime Medicine also benefits from a relationship with Beam Therapeutics. Prime and Beam are separate companies that both emerged from the laboratory of David Liu. Sharing many common interests, Prime and Beam have built a partnership to form a collaborative approach to fighting disease and accelerating the development of prime editing to deliver therapies for patients. In the areas of partnership, Prime Medicine and Beam share research, expertise, and intellectual property for assays, know-how, delivery, and manufacturing.

The Broad Institute of MIT and Harvard has extended a license for prime editing technology to Prime Medicine for human therapeutic uses under the Broad Institute’s inclusive innovation model.

Photo: Keith Gottesdiener, CEO of Prime Medicine

Author: Rare Daily Staff

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