How GX-03's Trial Design Supports Meaningful Efficacy Assessment

Bradley Burnam, founder and CEO of Turn Therapeutics, recently provided an overview of the statistical design behind the final stage 2 protocol of the company's phase 2 trial evaluating GX-03 in atopic dermatitis (AD).¹ Burnam explained why the trial uses the Hochberg multiple testing procedure across a family of related efficacy end points and how patients are stratified by baseline Eczema Area and Severity Index (EASI) score.

Why Hochberg's Procedure Fits Eczema End Points

Traditional trials allocate a fixed amount of statistical alpha to test a single primary end point, Burnam said, leaving no path to statistical significance on secondary endpoints if the primary endpoint fails to reach it.

"In a traditional clinical trial, if you fail on that primary end point, you're kind of out of luck for the rest of them. You don't get the opportunity to prove statistical significance," Burnam said.

Burnam said the FDA has published guidance supporting evaluation of a related family of end points, and eczema trials are well-suited to this approach given the range of clinically relevant measures available.

"Eczema is the perfect example of this, because you have got EASI 50% reduction, EASI 75% reduction, EASI 90% reduction. Is their itch getting better? Are there lesions clinically less severe?" Burnam said.

Hochberg's procedure ranks end points within that family from the worst P-value to the best, testing sequentially, so significance on the first result implies significance on the rest, Burnam said.

"It essentially spends the alpha in a very efficient way to allow us to test for multiple end points," Burnam said.

Stratifying Patients By Baseline EASI Score

Burnam also described how the trial stratifies patients into 3 baseline EASI groups, informally mild, moderate, and severe, to allow balanced comparisons within each severity band rather than mixing widely different baseline disease levels.

"We want to make sure that we're getting buckets of patients and that they're balanced within each bucket," Burnam said. The strata span EASI scores of 1.1 to 7.0, 7.1 to 15.9, and 16 and above, he said.

Burnam said the design ensures the trial evaluates every end point on equal footing rather than favoring a single result.

"We're not simply cherry picking the one that we think works best. We're giving it a chance to really work across all the different strata," Burnam concluded.

Reference

1. Turn Therapeutics announces final stage 2 design and data-driven expansion of GX-03 phase 2 program in atopic dermatitis. News release. Turn Therapeutics July 7, 2026. Accessed July 8, 2026. https://ir.turntherapeutics.com/news-releases/news-release-details/turn-therapeutics-announces-final-stage-2-design-and-data-driven