Design Therapeutics (NASDAQ:DSGN) outlined its near-term clinical priorities and key upcoming data readouts during a conference discussion with Leerink Partners’ Joe Schwartz, featuring comments from CEO Pratik Shah. The conversation focused on the company’s Friedreich’s ataxia (FA) program, ongoing work in Fuchs’ endothelial corneal dystrophy (FECD), and preclinical progress in myotonic dystrophy type 1 (DM1), along with timing expectations for multiple data updates in the second half of the year.
Friedreich’s ataxia: focus on endogenous frataxin restoration
Shah emphasized that FA is caused by low levels of “normal endogenous frataxin,” framing the central therapeutic objective as increasing frataxin produced by the patient’s own cells. He identified the most important upcoming milestone for the FA program as whether the company can demonstrate an increase in normal endogenous frataxin in patients in its multiple-dose RESTORE-FA study.
Assay work, reference studies, and selectivity rationale
Shah said the company has invested in assay validation and in generating reference data sets to contextualize results. He described running “highly validated” mRNA and protein assays and conducting background reference studies to understand frataxin levels in FA patients and in healthy carriers. He also discussed how the field has viewed frataxin increases, citing commentary from other sponsors suggesting that “any increase in frataxin” has been considered a success criterion in some regulatory discussions, and adding that reaching levels in the healthy-carrier range would reduce doubt about sufficiency.
On the question of GeneTAC selectivity, Shah pointed to preclinical work across multiple FA patient-derived cell types. He said GeneTAC molecules increased endogenous frataxin RNA and led to downstream effects including normalization of protein levels and improvements in functions such as cis-aconitate and cellular respiration. He added that exposure of wild-type genotype cells to an FA GeneTAC molecule had no impact because the repeat number in the wild-type allele is short and therefore does not produce a functional consequence when treated.
RESTORE-FA design, exposure targets, and timing
Shah said the company is running multiple ascending dose studies in FA patients following single-dose studies in healthy volunteers, where it confirmed safety/tolerability and observed a dose-to-exposure relationship consistent with non-clinical studies. He described a cohort-by-cohort escalation approach with safety as the gating criterion and said the objective remains to evaluate the frataxin response after 12 weeks of dosing. He said the company anticipates having that 12-week data in the second half of the year, with the exact timing driven mostly by operational factors and how many cohorts are needed to reach clear conclusions.
In discussing exposures believed to be necessary for meaningful frataxin increases, Shah connected the company’s target to DT-216 potency in cellular systems, stating that approximately 10 nanomolar exposures provide full pharmacology if exposure duration is sufficient. He referenced FA patient trials run in 2023, saying the company saw about 8–10 nanomolar exposure at day 2, but that drug levels were “almost all gone by day 7,” effectively turning what was intended to be a multiple ascending dose study into a set of single-dose administrations one week apart. Despite the limited exposure duration, he said the company observed an “unmistakable” increase in frataxin RNA expression at that time point in both muscle biopsy samples and peripheral blood cells, which he described as the first validation in humans of the 10 nanomolar exposure target derived from cellular studies.
Shah also described a hypothesis that sustaining plasma exposure in the “tens of nanomolar” range could support sustained frataxin response. He said the 12-week study duration is designed to allow drug and pharmacology to reach steady state, noting frataxin protein has an estimated 10-day to two-week half-life.
Patient population and endpoints in the FA study
Shah described RESTORE-FA enrollment criteria as “pretty permissive” beyond genetic confirmation of FA, including ambulatory and wheelchair-bound patients. He said the current study explores both IV and subcutaneous (sub-Q) administration to help determine dose route, dosing interval, and the frataxin response to inform future clinical investigation. While functional assessments are customary in FA trials and are being performed, he said the primary goal of the study is to look for a frataxin response.
Pipeline updates: FECD biomarker study and DM1 program differentiation
In FECD, Shah said the company is conducting an exploratory Phase 2 biomarker study in late-stage patients. He described the eventual product goal as an eye drop intended to slow or stop disease progression, potentially preserving visual quality in patients diagnosed earlier in the disease course. Because demonstrating target engagement has been challenging, he said the company developed a potential biomarker approach by measuring splicing from corneal tissue that would otherwise be discarded following corneal transplant surgery. He acknowledged key limitations: pre-treatment tissue cannot be collected from the same patient, the study population is very late-stage and already scheduled for surgery, and the approach could yield a false negative. However, he said seeing any impact on splicing relative to reference splice data would provide evidence the eye drops are affecting pathogenic spliceopathy. Shah said the FECD study results are also expected in the second half of the year.
For DM1, Shah highlighted DT-818 as a small-molecule approach rather than an oligonucleotide, which he said differentiates it from other clinical-stage programs targeting DMPK. He said DT-818 distributes naturally across affected tissues and is designed to recognize pathogenic CTG repeat expansions and dial down expression of the mutant DMPK allele while sparing the wild-type kinase. Shah cited preclinical observations of over 90% reduction in toxic DMPK RNA as visualized by RNA foci, with corresponding improvements in splice index. He also discussed repeat-length dynamics in affected tissues—suggesting that reported repeat numbers can be much lower than those present in muscle—and said DT-818 showed comparable pharmacology across a wide range of repeat lengths. Shah added that while IV is the main focus, DT-818—like DT-216—also appears bioavailable by sub-Q administration, which could be relevant if it translates clinically.
Shah also noted that lessons from DT-216/DT-216P and DT-168 have been applied to DT-818, including work on developing pharmaceutically suitable injection products and running biomarker studies with rigorous measurements.
On financial resources, Shah stated the company has over $200 million in cash and that its current cash position supports its plan “into 2029.” He said the business plan is designed to reach positive clinical proof of concept in at least one of its target areas, with multiple updates anticipated in the second half of the year.
About Design Therapeutics (NASDAQ:DSGN)
Design Therapeutics, Inc a biopharmaceutical company, researches, designs, develops, and commercializes small molecule therapeutic drugs for the treatment of genetic diseases in the United States. The company utilizes its GeneTAC platform to design and develop therapeutic candidates for inherited diseases caused by nucleotide repeat expansion. Its lead product candidates for potentially disease-modifying treatment comprises Friedreich Ataxia, a monogenic, autosomal recessive, progressive multi-system disease that affects organ systems dependent on mitochondrial function that brings to neurological, cardiac, and metabolic dysfunction; Myotonic Dystrophy Type-1, a dominantly-inherited, monogenic progressive neuromuscular disease affecting skeletal muscle, heart, brain, and other organs; Fuchs Endothelial Corneal Dystrophy, a genetic eye disease characterized by bilateral degeneration of corneal endothelial cells and progressive loss of vision; and Huntington's Disease, a dominantly inherited, monogenic neurodegenerative disease characterized by movement, cognitive, and psychiatric disorders.
