Korro Bio and Frequency Therapeutics to merge


Korro Bio, Inc., an RNA editing company focused on the discovery and development of novel genetic medicines, and Frequency Therapeutics, Inc. have entered into a definitive merger agreement to combine the companies in an all-stock transaction. 

The combined company will focus on the advancement of Korro Bio’s portfolio of RNA editing programs, is expected to operate under Korro Bio, Inc. and will apply to trade on Nasdaq under the ticker symbol KRRO.

Korro Bio has secured commitments from a syndicate of life sciences investors for a planned concurrent $117 million financing, co-led by Surveyor Capital (a Citadel company) and Cormorant Asset Management and participation from Atlas Venture, NEA, Platanus, Qiming Venture Partners USA, MP Healthcare Venture Management, Eventide Asset Management, Fidelity Management & Research Company LLC, Invus, Point72, Verition Fund Management, Monashee Investment Management, Sixty Degree Capital and additional investors. 

The financing is expected to close immediately prior to the completion of the merger. The combined company is expected to have approximately $170 million in cash, cash equivalents and marketable securities at close after estimated transaction expenses. The pro-forma cash balance is expected to provide a cash runway through several value-creating milestones and into 2026. The merger and related financing are expected to close in the fourth quarter of 2023, subject to approval by Frequency Therapeutics’ stockholders and other customary closing conditions.

“RNA editing, specifically utilizing our OPERA platform, holds significant promise to transform the therapeutic landscape for rare and common diseases. The ability to make a single base change on RNA using a simple drug product provides an opportunity to modify disease in an unprecedented manner,” said Ram Aiyar, chief executive officer of Korro Bio. 

“The power of our OPERA platform is exemplified by our lead program in AATD, where we have demonstrated an increase of normal A1AT protein to 85% of total protein in circulation, which has the potential of disease-modifying effects. We are committed to creating value for Korro Bio’s and Frequency Therapeutics’ stockholders as we work to develop a novel class of innovative medicines that have the potential to improve the lives of patients.”

Lead program for AATD

Korro Bio is advancing its lead program for AATD to a clinical trial and intends to submit a regulatory filing in the second half of 2024. AATD is an inherited disease that results from a single genetic defect that manifests itself as a broad spectrum of clinical pathologies. A majority of the patients are diagnosed later in life, having multiple clinical effects including liver disease and lung disease, eventually leading to organ transplant in some cases. 

Studies suggest that clinical unawareness of AATD results in a significant number of patients that go undiagnosed or misdiagnosed with approximately 100,000 patients in the U.S. currently identified with AATD. Korro Bio’s lead program is focused on precisely and transiently editing the genetic mutation in RNA rather than permanently altering DNA. Korro Bio has also demonstrated the ability to edit within the coding region of the SERPINA1 gene showing translation from the PiZ mouse model to non-human primates.

“Following comprehensive review and consideration of our strategic options, management and our board of directors believe the merger with Korro Bio provides the best opportunity for the company and its stockholders,” said David. L. Lucchino, chief executive officer of Frequency Therapeutics. 

“Korro Bio’s RNA editing technology leverages genetics transiently, expanding the target space to intervene in biology in a unique manner. We are confident in their ability to bring forward important genetic medicines with the potential to transform the lives of patients.”

Korro Bio’s proprietary RNA editing platform enables a breadth of indications with an initial focus on six potential programs that are all wholly owned, including AATD.

“This transformative transaction enables us to take our lead program in AATD into the clinic and progress our pipeline,” said Vineet Agarwal, chief financial officer of Korro Bio. 

“In addition, we will be able to fund our company through several value-creating milestones into 2026.”

Proposed merger

Pre-merger Frequency Therapeutics stockholders are expected to own approximately 8% of the combined company and pre-merger Korro Bio stockholders (including those purchasing Korro Bio shares in the private financing) are expected to own approximately 92% of the combined company.  Under the terms of the merger agreement, stockholders of Korro Bio will receive newly issued shares of Frequency Therapeutics common stock pursuant to a formula set forth in the merger agreement. The percentage of the combined company that Frequency Therapeutics stockholders will own upon the closing of the merger is subject to adjustment based on the amount of Frequency Therapeutics’ net cash at the time of closing.

Frequency Therapeutics has discontinued development of its remyelination program for multiple sclerosis as it explores strategic alternatives for the program. If Frequency Therapeutics has not otherwise monetized its remyelination program for multiple sclerosis prior to the closing of the proposed merger, Frequency Therapeutics stockholders of record will be issued a contingent value right (CVR) for each outstanding share of Frequency Therapeutics common stock held by such Frequency Therapeutics stockholder prior to the closing of the proposed merger. The CVR would represent the right to receive certain cash payments from proceeds received by Frequency Therapeutics related to its remyelination program for multiple sclerosis that is in preclinical development.

The merger agreement has been unanimously approved by the boards of directors of both companies. 

About Korro Bio

Korro Bio is an RNA editing company focused on the discovery and development of a new class of precision genetic medicines for rare and highly prevalent diseases. RNA editing is a natural physiological process that occurs in cells, including a mechanism mediated by an enzyme called adenosine deaminase acting on RNA (ADAR). Korro Bio’s RNA editing approach involves co-opting this endogenous editing system via a proprietary engineered oligonucleotide to introduce precise edits to RNA. The technology enables the development of therapeutic candidates that deliver the functional benefits of gene therapy with a transient, titratable and specific treatment regimen, offering the potential to advance genetic medicines beyond rare genetic diseases into larger patient populations with common diseases. 


Korro Bio’s platform, OPERA (oligonucleotide promoted editing of RNA), builds on an understanding of ADAR biology, and combines oligo discovery, chemistry and data-driven design with clinically validated delivery vehicles, to achieve highly selective RNA editing product candidates. OPERA is designed to enable the precise repair and modulation of disease-causing mutations and protein function to provide new possibilities for treating diseases in which progress with existing technologies has been slow to materialize.

Korro Bio’s lead program in AATD

AATD is an inherited genetic disorder that can cause severe progressive lung and liver disease due to a lack of normal alpha-1 antitrypsin protein (A1AT). Korro Bio’s AATD product candidate is an oligonucleotide that uses an established lipid nanoparticle (LNP) based delivery system administered intravenously to restore production of normal functional A1AT to liver hepatocytes. The oligonucleotide drug product co-opts the naturally occurring ADAR pathway, repairing disease-related mutations and restoring production of normal A1AT.

Korro Bio believes this will provide clinically differentiated benefits for both liver and lung function in affected individuals. Proof of concept has been shown in preclinical models, and studies in mice and non-human primates demonstrated high editing efficiency and expression of functional A1AT protein to support potential modification of disease progression. Korro Bio intends to submit a regulatory filing in the second half of 2024.

About Korro Bio’s portfolio of programs 

Korro Bio’s wholly owned, early-stage pipeline targets several diseases, such as Parkinson’s disease, severe alcoholic hepatitis, amyotrophic lateral sclerosis, subsets of pain, and cardiometabolic disease.

About Frequency Therapeutics

Headquartered in Lexington, Mass., Frequency Therapeutics is pioneering a new category in regenerative medicine that aims to restore human function by developing therapeutics that activate a person’s innate regenerative potential within the body through the activation of progenitor cells.

Frequency Therapeutics’ lead preclinical program is designed to activate oligodendrocyte precursor cells with the goal of driving remyelination and potential functional recovery for individuals living with multiple sclerosis. 

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