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EXHIBIT 99.1 Aclaris Therapeutics Reports First Quarter 2021 Financial Results and Provides a Corporate Update • Data from Phase 2a Trial of ATI - 1777 for Moderate to Severe Atopic Dermatitis Expected in Second Quarter of 2021 • Advancing ATI - 450 with Planned Initiation of Phase 2b Trial for Moderate to Severe Rheumatoid Arthritis in Second Half of 2021 • Advancing ATI - 450 into Two Additional Indications : Hidradenitis Suppurativa and Psoriatic Arthritis • Expands Scientific Advisory Board WAYNE , Pa . , May 7 , 2021 ( GLOBE NEWSWIRE ) -- Aclaris Therapeutics , Inc. ( NASDAQ : ACRS ) , a clinical - stage biopharmaceutical company focused on developing novel drug candidates for immuno- inflammatory diseases , today announced its financial results for the first quarter of 2021 and provided a corporate update . " We're very pleased with the progress of our novel immuno - inflammatory drug development pipeline and look forward to reporting data from our Phase 2a trial of ATI - 1777 in the second quarter of 2021 , " said Dr. Neal Walker , President & CEO of Aclaris . " ATI - 1777 is our second development program generated by KINect , our proprietary drug discovery platform . After generating proof of mechanism in inhibiting TNFα , IL1ẞ and IL6 in our Phase 2a trial of ATI - 450 in moderate to severe rheumatoid arthritis , we are planning to move ATI - 450 forward with a Phase 2b trial in moderate to severe rheumatoid arthritis in the second half of 2021 and planning to initiate two additional trials of ATI - 450 in hidradenitis suppurativa and psoriatic arthritis . " Research and Development Highlights : The global COVID - 19 pandemic continues to rapidly evolve and has caused and may continue to cause Aclaris to experience disruptions that could impact the timing of its research and development and regulatory activities listed below . • ATI - 450 , an investigational oral small molecule MK2 inhibitor compound : O ATI - 450 - RA - 201 : A Phase 2a , multicenter , randomized , investigator and patient - blind , sponsor - unblinded , parallel group , placebo - controlled clinical trial to investigate the safety , tolerability , pharmacokinetics and pharmacodynamics of ATI - 450 in 19 subjects with moderate to severe rheumatoid arthritis . The trial consisted of a 12 - week treatment period and a 4 - week follow - up period . Two subjects withdrew from the trial during the treatment period , one in the treatment arm and one in the placebo arm . ■ Final per - protocol analysis , which consisted of 17 subjects who completed the treatment period ( 15 in the treatment arm and two in the placebo arm ) , confirmed that ATI - 450 demonstrated durable clinical activity , as defined by a marked and sustained reduction in DAS28 - CRP and improvement of ACR20 / 50 / 70 responses over 12 weeks . Overall , ATI - 450 was generally well tolerated . There were no treatment - related serious adverse events and all adverse events were mild to moderate . There was one non - treatment - related serious adverse event ( COVID - 19 ) reported in the 4- week follow - up period of the trial in a subject who was no longer receiving treatment . The subject withdrew during the 4 - week follow - up period of the trial . o Aclaris intends to progress ATI - 450 into a Phase 2b trial in moderate to severe rheumatoid arthritis in the second half of 2021 .