Addition Therapeutics to Unveil Novel RNA-Gene Therapy Hybrid at ASGCT

SOUTH SAN FRANCISCO, Calif. – April 27, 2026 – Genetic medicine company Addition Therapeutics is set to emerge from a period of quiet development into the scientific spotlight, announcing it will present pivotal data on its novel therapeutic platform at the upcoming American Society of Gene & Cell Therapy (ASGCT) 29th Annual Meeting in May. The company aims to redefine the boundaries of genetic medicine with what it calls a “best of both modalities” approach, combining the precision of RNA therapeutics with the durability of gene therapy.

The presentations, scheduled for the premier gene and cell therapy conference in Boston, will offer the first detailed public look at Addition’s lead programs for Fabry disease and a rare form of obesity, alongside data on its underlying PRINT™ technology. The company’s ambitious strategy targets severe, lifelong diseases with the goal of delivering functional cures, a promise that has already attracted $100 million in financing from a high-profile syndicate of investors, including the Gates Foundation.

Bridging the Gap Between RNA and Gene Therapy

At the heart of Addition’s strategy is its proprietary PRINT™ (Precise RNA-Mediated Insertion of Transgenes) technology. The platform seeks to solve a fundamental challenge in genetic medicine: the trade-off between the temporary nature of RNA drugs and the potential safety and delivery issues of traditional gene therapies.

Current gene therapies often rely on viral vectors, such as adeno-associated viruses (AAVs), to deliver genetic payloads into cells. While effective, these methods can trigger immune responses and sometimes insert genetic material randomly into the host genome, posing a risk of disrupting essential cellular functions. Conversely, RNA-based therapies like mRNA or siRNA are highly specific and generally safer, but their effects are transient, requiring repeated dosing.

Addition’s all-RNA, non-viral system aims to deliver a one-time, durable treatment without these drawbacks. The technology, which originated from foundational research at the University of California, Berkeley, uses a clinically validated lipid nanoparticle (LNP) to deliver its RNA-based cargo into cells. Once inside, a retrotransposase enzyme—encoded by one of the delivered RNA molecules—creates a DNA copy of the therapeutic transgene. This DNA is then precisely inserted into a specific, highly conserved "safe-harbor" site within the cell's ribosomal DNA.

By targeting this specific genomic location, the company claims its PRINT™ platform can ensure stable, long-term expression of a therapeutic protein without interfering with native genes. This approach effectively turns the patient's own cells into sustainable bio-factories for producing a needed protein or antibody, with the potential for durability lasting the lifetime of the cell. This non-viral, "dosed-to-effect" method could represent a significant leap forward in creating safer and more scalable genetic medicines.

A Broad Pipeline Targeting High Unmet Needs

The upcoming ASGCT meeting will serve as a crucial proving ground for the versatility of the PRINT™ platform. Addition will present data from a diverse pipeline that spans rare genetic disorders, metabolic diseases, and infectious diseases.

The company's two lead programs target conditions with significant unmet needs. For Fabry disease, a rare lysosomal storage disorder, patients currently rely on lifelong, burdensome enzyme replacement therapies (ERT) or chaperone therapies. Addition's preclinical data will showcase a potential one-time treatment designed to insert the GLA transgene, enabling the body to produce its own functional alpha-galactosidase A enzyme. This approach could liberate patients from the constant cycle of infusions and potentially offer more comprehensive protection against the disease's devastating effects on the heart and kidneys. This positions the company in a competitive but high-value space alongside other gene therapy developers like Sangamo Therapeutics and UniQure.

The second lead program, for an undisclosed rare obesity indication, is particularly novel. An oral presentation titled "Turning hepatocytes into incretin factories with PRINT" suggests a strategy to engineer liver cells to produce incretins, hormones that regulate appetite and blood sugar. This could offer a transformative solution for patients with rare genetic forms of obesity characterized by insatiable hunger, a condition for which current options are limited.

Beyond its lead programs, Addition will also present data from key collaborations that underscore the platform's breadth. A poster presentation will detail an HIV program, supported by a $4.2 million grant from the Gates Foundation, which aims to create an in vivo antibody-production platform. The goal is a single-dose therapy that provides lifetime protection against HIV by enabling the body to continuously produce broadly neutralizing antibodies—a potential game-changer for disease prevention, especially in low-resource settings. Additional presentations will cover research in ocular diseases, demonstrating the technology's potential for localized delivery to the eye.

A Calculated Strategy Backed by Top-Tier Investors

Addition Therapeutics' emergence is not just a scientific event but a calculated business maneuver. After operating in stealth, the company's $100 million financing announcement in late 2025 signaled strong investor confidence. The syndicate includes industry heavyweights like SR One, Pivotal Life Sciences, and Abingworth, whose backing provides significant validation for the PRINT™ platform's potential.

The company’s strategy focuses on targeting rare diseases first—a well-established path in biotech for achieving faster regulatory review and demonstrating proof-of-concept in well-defined patient populations. Success in these initial indications, such as Fabry disease, is intended to de-risk the technology and pave the way for expansion into larger, related patient populations. For example, the Fabry program could serve as a blueprint for a broad set of diseases currently treated with enzyme replacement therapies, while the rare obesity program could open doors to treating broader metabolic conditions.

The collaborations with the Gates Foundation and undisclosed top-10 pharmaceutical companies on programs in HIV, CAR-T, and obesity further bolster the company's standing. These partnerships not only provide non-dilutive funding and external validation but also suggest that major players in the industry see significant potential in the PRINT™ platform. As Addition prepares to share its data at ASGCT, it will be closely watched by the scientific community, competitors, and potential partners, all keen to see if this "best of both" approach can deliver on its transformative promise for patients.