GEN ranks not only the top 10 publicly traded developers of editing-based therapies, but the top five privately held companies, listed below. The privately held companies have been ranked by total capital raised as confirmed by the companies, or as reported by PitchBook (for companies that had not replied to GEN queries at deadline).

The five leading developers have collectively raised more than $2.25 billion, reflecting investor confidence in the emerging field. That number is up 17.5% from the $1.917 billion-plus raised collectively by last year’s top five. Below the top five, privately held companies that ranked sixth to tenth have raised a combined $1.122 billion in total capital, up more than 28% from the $874 million raised by the next five last year.

Just missing the top five was sixth-ranked Atsena Therapeutics ($328 million, of which $150 million came from an oversubscribed Series C financing completed in January). Seventh-ranked Scribe Therapeutics has garnered $260 million-plus—consisting of $120 million in venture capital, $140 million in upfront payments from partners that include Prevail, Biogen, and Sanofi; and undisclosed milestone payments from Prevail and Sanofi. Ranking eighth to tenth were Tune Therapeutics ($215 million); EdiGene (RMB 1.182 billion [$164 million]); and Pairwise ($155 million).

Additional companies positioning themselves to grow into top-10 privately held edited therapy developers include SparingVision (€135 million [$144 million]); Epicrispr Biotechgnologies ($123 million, according to PitchBook, including a $68 million Series B financing secured in March); and iECURE ($115 million), founded to advance the life’s work of gene therapy pioneer James M. Wilson, MD, PhD.

1. Tessera Therapeutics       

Tessera Therapeutics, a Flagship Pioneering company, added to its total capital raised last December when it secured an undisclosed initial investment from the Bill and Melinda Gates Foundation under an agreement to jointly fund the company’s in vivo program for sickle cell disease (SCD), to support its advance into clinical trials. The investment could potentially grow up to $50 million, which would bring Tessera’s capital well past the “approximately $600 million” that earned the company the top spot on GEN’s 2024 A-List of top five privately held editing therapy developers. Tessera’s honors include the Prix Galien USA 2023, won in the Best Startup category. Tessera’s non–long nonterminal repeat retrotransposons write genes into the genome through a method that entails binding RNA, binding DNA, nicking DNA, then priming reverse transcription.

2. Mammoth Biosciences 

Mammoth Biosciences achieved a clinical milestone in May when it nominated its first clinical development candidate, MB-111, a potential first-in-class in vivo ultracompact CRISPR therapy for familial chylomicronemia syndrome and severe hypertriglyceridemia. MB-111 uses CasPhi, an ultracompact CRISPR in vivo gene editing system less than half the size of first-generation Cas9-based systems, encapsulated in a lipid nanoparticle for delivery to the liver after IV administration. In January, Mammoth researchers posted a preprint on bioRxiv reporting they established proof-of-concept for NanoCas™, the first ultracompact CRISPR system capable of efficient extrahepatic editing when delivered systemically using a single adeno-associated viral (AAV) vector. Mammoth’s capital haul lives up to the company name at $465 million, including about $365 million in equity capital and $100 million-plus in non-dilutive funding from big-name biopharma partners such as Regeneron Pharmaceuticals, Bayer, and Vertex Pharmaceuticals.

3. nChroma Bio

nChroma Bio emerged last December from the merger of two editing therapy startups. One is Nvelop Therapeutics, which exited from stealth last year with $100 million (seed funding raised in 2022) and a pair of validated in vivo delivery approaches developed by gene editing pioneers David R. Liu, PhD, and J. Keith Joung, MD, PhD. The other is Chroma Medicines, which raised $257 million toward developing programmable epigenetic editors—placing it fifth on last year’s A-List. Upon combining, the companies completed an oversubscribed $75 million financing intended to help build a robust pipeline of next generation hepatic and extrahepatic targeted therapies. That pipeline is led by CRMA-1001, an epigenetic editor in development as a potential functional cure for chronic hepatitis B and hepatitis D. nChroma says the $75 million financing will also support “meaningful” clinical data for CRMA-1001, for which the company plans to submit a clinical trial application later this year.

4. Arbor Biotechnologies

Arbor Biotechnologies in March completed a $73.9 million Series C financing to support clinical development of its lead candidate ABO-101, a treatment for primary hyperoxaluria type 1 (PH1), and advance to clinical trials pipeline programs that include a reverse transcriptase (RT) editing program for a rare liver disease and a program targeting amyotrophic lateral sclerosis (ALS). At the recent 2025 American Society of Gene and Cell Therapy (ASGCT) 28th Annual Meeting, Arbor showcased data supporting the therapeutic potential of ABO-101 in PH1 and clinical evaluation in the Phase I/II redePHine trial (NCT06839235), plus in vivo proof-of-concept data supporting the first type V gene editing program for SOD1-ALS, and the first disclosure of its therapeutic gene editing approach to Angelman syndrome. Arbor has raised more than $400 million—including $300+ million from equity financings, and $100+ million from partnerships.

5. ReCode Therapeutics

ReCode Therapeutics in March received the FDA’s Orphan Drug designation for RCT2100, a messenger RNA (mRNA) therapy being developed to treat cystic fibrosis (CF). RCT2100 is being evaluated in a Phase Ib study in patients with CF who do not respond to or are intolerant of current modulator therapies. The study is part of a multi-part trial (NCT06237335) enrolling patients in the United States, United Kingdom, France, and the Netherlands. ReCode has raised a total $387 million in capital—including the up-to-$15 million invested by the Cystic Fibrosis Foundation toward the company’s gene correction research program, which aims to develop and commercialize new treatments for people with CF, including those with genotypes that do not respond to or are intolerant to approved CFTR modulators.

Also read GEN‘s Top 10 Publicly Owned Editing Therapy Companies list.