BOSTON, MASSACHUSETTS, May 04, 2026
Ascidian Therapeutics has announced the completion of the adult dose escalation phase in its Phase 1/2 STELLAR clinical trial evaluating ACDN-01, a first-in-class RNA exon editing therapy for Stargardt disease, a rare inherited retinal disorder with no approved treatments. The company also revealed plans to expand the trial to include pediatric patients aged 12 and older, marking a critical step toward addressing early-stage disease intervention. In parallel, Ascidian has launched STARPATH, an observational prescreening study designed to accelerate patient identification and streamline enrollment for future clinical trials, reinforcing its commitment to advancing precision genetic medicine.
STELLAR Trial Demonstrates Progress in RNA Editing Therapy
The STELLAR Phase 1/2 clinical trial is a multi-center, open-label, dose-escalation study assessing the safety and preliminary efficacy of ACDN-01 in patients with Stargardt disease and other ABCA4-related retinopathies. The completed dose escalation phase enrolled 10 adult participants aged 18 to 77, evaluating the effects of a single subretinal injection of the investigational therapy.
Initial first-in-human safety data from the study will be presented at the American Society of Gene & Cell Therapy Annual Meeting 2026, providing important insights into the therapy’s clinical potential and tolerability profile. The expansion to pediatric patients is particularly significant, as earlier intervention may improve long-term outcomes in progressive retinal diseases characterized by early-onset vision loss.
RNA Exon Editing Offers Breakthrough Genetic Approach
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ACDN-01 represents a novel RNA-based therapeutic approach that differs fundamentally from traditional gene therapy and gene editing technologies. Instead of modifying DNA, ACDN-01 uses RNA exon editing to restore full-length, functional ABCA4 protein, directly addressing the genetic root cause of Stargardt disease. This approach is especially valuable given the large size and high mutation variability of the ABCA4 gene, which make it challenging to target using conventional gene replacement or base editing methods.
Delivered via a single adeno-associated virus (AAV) vector, ACDN-01 has demonstrated efficient and durable RNA editing in preclinical models, offering the potential for a one-time treatment with sustained therapeutic benefit. By avoiding permanent genomic modification and the introduction of foreign enzymes, this technology provides a potentially safer and more precise alternative in the evolving field of genetic medicine.
Expanding Clinical Strategy and Rare Disease Innovation
The launch of the STARPATH observational study further strengthens Ascidian’s clinical development strategy by enabling genetic screening and high-resolution retinal imaging to better characterize disease progression and identify eligible patients for future trials. Stargardt disease affects approximately 30,000 individuals in the United States, with symptoms typically emerging in childhood or early adulthood, leading to progressive vision loss and significant impact on quality of life.
From a GxP perspective, both STELLAR and STARPATH are conducted under Good Clinical Practice (GCP) standards, ensuring data integrity, patient safety, and regulatory compliance. The expansion of ACDN-01 into broader patient populations highlights the growing importance of RNA-based therapeutics in addressing complex genetic disorders, particularly those with limited or no treatment options.
Ascidian’s innovative platform underscores a broader industry shift toward precision medicine and next-generation biologics, offering new hope for patients with inherited retinal diseases. If successful, ACDN-01 could represent a paradigm shift in treating Stargardt disease, paving the way for scalable RNA editing solutions across multiple genetic conditions and reinforcing Ascidian’s leadership in cutting-edge biopharmaceutical innovation.
Source: Ascidian Therapeutics press release
