RAPT Therapeutics has announced the initiation of a Phase 2a clinical trial to evaluate RPT193 as a potential treatment for moderate-to-severe asthma. This global, multicenter study aims to assess the efficacy and safety of RPT193, an oral, once-daily monotherapy, in patients whose asthma is partially controlled by standard medications. The trial is a randomized, double-blind, placebo-controlled study conducted over 14 weeks.
RPT193: Targeting Th2 Cell Migration in Asthma
RPT193 is a CCR4 antagonist designed to selectively inhibit the migration of Th2 cells into inflamed tissues. Type 2-high asthma, characterized by eosinophilic airway infiltrate and overexpression of Th2 cytokines (IL-4, -5, and -13), is the initial focus of this trial. By blocking CCR4, RPT193 aims to reduce the inflammatory response driven by Th2 cells in the airways.
Trial Design and Endpoints
The Phase 2a trial will enroll approximately 100 adult patients with moderate-to-severe Type 2-high asthma, randomized 1:1 to receive either 400 mg of RPT193 or a placebo once daily. Patients will undergo a 28-day run-in period with standardized regimens of inhaled corticosteroids (ICS) and long-acting beta agonists (LABA). During the 14-week treatment period, background ICS and LABA will be gradually tapered, with patients receiving RPT193 or placebo as monotherapy for the final 3-4 weeks.
The primary endpoint of the trial is the proportion of patients who experience a loss of asthma control, defined by criteria such as a significant reduction in morning peak expiratory flow, increased use of reliever inhalations, increased ICS dose, or asthma exacerbations requiring systemic corticosteroids, hospitalization, or emergency room visits.
Asthma and the Need for New Therapies
Asthma, a chronic inflammatory disease affecting an estimated 25.2 million individuals in the United States, is characterized by airway obstruction, swelling, and mucus hyperproduction. Type 2 asthma, driven by overactive Th2 cells, accounts for approximately 80% of asthmatic children and 60% of asthmatic adults. Standard treatments include inhaled corticosteroids and beta agonists, with biologics available for uncontrolled cases. RAPT Therapeutics believes that RPT193, as an oral, upstream alternative to existing therapies, could address a significant market opportunity.
Prior Clinical Evidence
RPT193 has previously demonstrated promising results in a Phase 1b trial for atopic dermatitis, showing clinically meaningful improvements in disease signs and symptoms. Brian Wong, M.D., Ph.D., President and CEO of RAPT, stated that the company views asthma as the next key indication in their pipeline-in-a-product strategy, building upon the observed efficacy and safety profile in atopic dermatitis.
