Why Is Design Therapeutics Stock Moving Lower Today?

Design Therapeutics Inc DSGN reported initial results from the company's Phase 1 multiple-ascending dose (MAD) clinical trial of DT-216 in patients with Friedrich ataxia (FA). 

As of a data cutoff date of Aug. 7, results showed that DT-216 was generally well-tolerated and achieved a statistically significant and dose-related increase in frataxin (FXN) mRNA levels in skeletal muscle biopsies.

Injection site reactions associated with the formulation excipients, or inactive ingredients, were observed across dose cohorts.

Design Therapeutics planned to reformulate its Friedreich ataxia drug following injection site reactions in a Phase 1 study.

The company plans to begin a new multiple-dose Phase 1 study in the second half of 2024, with initial data in the first half of 2025. 

Previously, in May, Design had guided that it expected to start a Phase 2 study in Friedreich Ataxia in the second half of this year.

Exploratory analyses of muscle FXN mRNA levels from the Phase 1 MAD study showed that:

FA patients in the 300 milligrams cohort had a 30% mean increase from baseline in FXN mRNA two days after the third weekly dose, which was significant compared to placebo (p<0.05), with a trend in increased FXN mRNA seven days post-dose.

The mean increase in FXN mRNA of the 300 milligrams cohort was above the 75th percentile of FA patients from the observational study.

There was a significant DT-216 dose-response trend and tissue exposure-response relationship with muscle FXN mRNA expression.

Based on current methods and procedures, the treatment effect of DT-216 on FXN protein was inconclusive due to high intra-individual variability, consistent with what was seen in the observational study.

There was a transient increase of FXN mRNA in peripheral blood mononuclear cells (PBMCs) 24 hours after dose, which is consistent with and confirms the results from the Phase 1 single ascending dose study. 

As of this data cutoff, PBMC FXN protein results are not available.

Price Action: DSGN shares are down 45.7% at $3.98 during the premarket session on the last check Tuesday.