- The stock price of Rapt Therapeutics Inc (NASDAQ: RAPT) increased by over 80% during intraday trading. This is why it happened.
The stock price of Rapt Therapeutics Inc (NASDAQ: RAPT) – a clinical-stage, immunology-based biopharmaceutical company focused on discovering, developing and commercializing oral small molecule therapies for patients with significant unmet needs in oncology and inflammatory diseases – increased by over 80% during intraday trading as it went from a previous close of $18.57 to a day high of $41.99.
Investors are responding positively to RAPT Therapeutics announcing positive topline results from its randomized placebo-controlled Phase 1b clinical trial of RPT193 as monotherapy in 31 patients with moderate-to-severe atopic dermatitis (AD). And after 4 weeks of treatment, patients with moderate-to-severe AD who received RPT193 showed a 36.3% improvement from baseline in the Eczema Area and Severity Index (EASI) score, a standard measure of disease severity, compared to 17% in the placebo group. But in the 2-week period following the end of treatment, the RPT193 group showed continued improvement and further separation from placebo with a 53.2% improvement in EASI at the six-week time point compared to 9.6% in the placebo group. This continued improvement may be related to RPT193’s mechanism of action — which is upstream of other agents targeting cytokines or signaling pathways.
In the Phase 1b study, 21 patients with moderate-to-severe atopic dermatitis were treated with 400 mg of RPT193, administered orally once a day for 4 weeks while 10 patients received placebo. And the RPT193 group showed clear improvement in key efficacy measures compared to placebo at the end of the 4-week treatment period, including improvement in the Eczema Area and Severity Index (EASI) score, validated Investigator Global Assessment (vIGA) and pruritis Numerical Rating Scale (NRS):
— Patients treated with RPT193 achieved a 36.3% improvement in EASI score from baseline compared with a 17.0% improvement in patients in the placebo group
— 42.9% of patients treated with RPT193 achieved a 50% improvement in EASI score (EASI-50) compared with 10.0% in the placebo group
— 4.8% of patients treated with RPT193 achieved a vIGA score of 0/1 and at least a two-point improvement over baseline compared with 0.0% in the placebo group; and
— 45% of patients treated with RPT193 achieved at least a 4-point reduction in the pruritus NRS score, compared with 22.2% in the placebo group
The patients were also evaluated for exploratory endpoints at 6 weeks (2 weeks after the end of treatment). At 6 weeks, the patients treated with RPT193 showed further improvement in EASI score and vIGA:
— Patients treated with RPT193 achieved a 53.2% improvement in EASI score from baseline compared with a 9.6% improvement in patients in the placebo group
— 61.9% of patients treated with RPT193 achieved EASI-50 compared with 20.0% in the placebo group; and
— And 14.3% of patients treated with RPT193 achieved a vIGA score of 0/1 and at least a two-point improvement over baseline compared with 0.0% in the placebo group
Based on exploratory statistical analyses, the difference between RPT193 and placebo on the percent change in EASI score and EASI-50 was statistically significant at Day 43 (p < 0.05). And no other endpoints or timepoints achieved statistical significance.
RPT193 was well-tolerated in the Phase 1b study. And no serious adverse events were reported and all adverse events reported were mild or moderate in intensity. The overall safety profile of RPT193 to date, including the Phase 1b study and the previously reported blinded safety data from our Phase 1a study in healthy volunteers, suggests RPT193 is a well-tolerated oral drug that would not require any laboratory safety monitoring.
In addition to the topline data reported today, RAPT plans to report additional data and analyses in a future publication or at an upcoming medical conference. And based on the efficacy and safety data observed in the Phase 1b study, RAPT plans to initiate a dose-ranging Phase 2b study in patients with moderate-to-severe AD and is also planning a Phase 2a study in asthma.
KEY QUOTES:
“These data strongly support the potential of RPT193 as a safe, once-daily, oral treatment for patients with atopic dermatitis which would be an attractive therapeutic alternative ahead of injectable drugs. We look forward to advancing RPT193 to a Phase 2b trial in atopic dermatitis and a Phase 2a trial in asthma.”
— Brian Wong, M.D., Ph.D., President and CEO of RAPT Therapeutics
“I am very excited about these results as they not only demonstrate clinically meaningful improvement after just four weeks of treatment, but also further improvement for two weeks after completion of treatment. This may suggest that this novel mechanism of action targeting CCR4 on Th2 cells could have prolonged, disease-modifying effects, which could differentiate it from other agents. Along with being an oral drug that seems to have promising clinical activity and a well-tolerated safety profile, RPT193 could fill a high unmet medical need for AD patients.”
— Emma Guttman-Yassky, M.D., Ph.D., the Waldman Professor of Dermatology and System Chair Department of Dermatology at the Icahn School of Medicine at Mount Sinai, and member of RAPT’s Scientific Advisory Board
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