RAPT Therapeutics Announces Positive Results from Phase 1a/1b Clinical Trial of Zelnecirnon for Atopic Dermatitis

November 27, 2023 - RAPT Therapeutics, Inc. announced the publication of results from its Phase 1a/1b clinical trial of zelnecirnon (formerly RPT193) in the journal Allergy. The trial demonstrated positive clinical and molecular effects in treating atopic dermatitis (AD), with significant improvements in key efficacy endpoints such as the Eczema Area and Severity Index (EASI), EASI-50, validated Investigator Global Assessment (vIGA), and pruritis Numerical Rating Scale (NRS) after four weeks of treatment.

In the Phase 1b portion of the trial, 31 patients with moderate-to-severe AD were treated with zelnecirnon or placebo. The zelnecirnon group showed a 36.3% improvement in EASI score from baseline, compared to 17.0% in the placebo group. Notably, the response deepened two weeks post-treatment, with a 53.2% improvement in EASI score at the six-week mark, compared to 9.6% in the placebo group.

Significant changes in the transcriptional profile of patients treated with zelnecirnon were observed at Day 29, correlating with clinical efficacy measures. Zelnecirnon was well tolerated, with no serious adverse events reported, and all adverse events were mild-to-moderate.

Brian Wong, M.D., Ph.D., President and CEO of RAPT Therapeutics, expressed enthusiasm about the data, highlighting zelnecirnon's potential as a safe, once-daily oral treatment for AD, offering an attractive alternative to injectable drugs. RAPT Therapeutics is progressing with a Phase 2b trial in AD and a Phase 2a trial in asthma.

Zelnecirnon, a small molecule oral therapy, targets the CCR4 receptor to inhibit the migration of Th2 cells into inflamed tissues, potentially modulating Th2 cell function and reducing inflammation. This mechanism offers therapeutic promise across a range of inflammatory diseases, including AD, asthma, and others.

Atopic dermatitis is a chronic, inflammatory skin disease that significantly impacts patients' quality of life. The development of zelnecirnon represents a potential advancement in the treatment of AD and other inflammatory disorders, addressing a significant unmet medical need with the convenience of oral dosing.