On May 7, 2024, Pfizer stated in a letter to a patient advocacy organization for Duchenne muscular dystrophy that the companyA participant in the Phase 2 DAYLIGHT study of an experimental gene therapy for Duchenne muscular dystrophy has suddenly died., For this reason, PfizerSuspension of Dosing Related to the Crossover Portion of the Phase 3 CIFFREO Trial。Duchenne Muscular Dystrophy (DMD) is an X-linked recessive genetic skeletal muscle disease caused by mutations in the dystrophin gene, and it is the most common muscular dystrophy among rare diseases. To date, there is no specific cure for DMD. The main treatment methods include standardized drug therapy, rehabilitation training, nutritional enhancement, and other symptomatic supportive treatments, with the aim of prolonging survival and improving quality of life.DAYLIGHTIt is a single-arm, non-randomized, open-label study including boys aged at least 2-4 years (including 3-4 year birthdays). All boys in the study need to test negative for neutralizing antibodies against AAV9, as measured by a study-specific screening test.The primary analysis of the trial is planned to be conducted after all participants complete their visits up to Week 52 (or withdraw from the study before Week 52). According to Pfizer, all participants will undergo five years of follow-up after receiving the gene therapy.The main completion date of the trial is expected to be December 27 this year, with full completion anticipated by January 2029.。In November 2022, Pfizer began dosing in younger patients with DMD in its gene therapy trial. According to reports,The young patient who died this time received fordadistrogene movaparvovec in early 2023.Due to the death of this boy, Pfizer suspended the cross-over portion of its Phase 3 CIFFREO study for patients aged 4-7.CIFFREOThe clinical trial is a Phase 3 global multicenter clinical trial conducted by Pfizer worldwide. Across 42 clinical trial sites globally (in Asia: Japan, South Korea, and Taiwan, China), a total of 99 DMD patients aged 4 years and older but under 8 years (including those turning 7-8 years old) were enrolled.Currently,Pfizer does not yet know the cause of the patient's death, nor whether the death is related to its treatment.Pfizer stated in the letter, "We do not yet have complete information and are actively working with the investigators at the trial site to understand what happened."Pfizer's study is one of several trials currently underway, with others including a Phase 3 placebo-controlled trial in older boys, the results of which are expected to be released this year. Pfizer has been hoping that positive data could support an approval application.In fact,Pfizer's research on DMD had previously slowed down due to safety concerns.As early as December 2021, Pfizer reported the death of a young male patient in a Phase 1 DMD trial. The company suspended screening and dosing for the study, and the FDA also placed the clinical study on hold. Later, Pfizer implemented safeguards to allow the study to resume. These measures included requiring patients to be closely monitored in the hospital for one week after treatment, among others.Even before that, the company had already recorded safety issues associated with the therapy in the Phase 3 trial testing its dynamic function. After reporting three adverse events, Pfizer revised the study protocol to exclude patients with certain genetic mutations.Brian Abrahams, an analyst at RBC Capital Markets, said that if the boy's death was related to Pfizer's treatment, it would be unusual. "Most serious side effects associated with Duchenne gene therapy are acute... We do not expect this mechanism or approach to produce delayed toxicity," Abrahams wrote in a client report.It is worth noting that,If fordadistrogene movaparvovec enters the market, it will become the second gene therapy for DMD.. The first is Sarepta Therapeutics' Elevidys.In June 2023, Sarepta Therapeutics received FDA accelerated approval for Elevidys (delandistrogene moxeparvovec-rokl), marking the entry of the first gene therapy for DMD into the market. Elevidys® is an AAV-based gene therapy used to treat non-ambulatory pediatric patients with DMD aged 4-5 years and confirmed DMD gene mutations. Last year,Elevidys Generated $200.4 Million in Net Product Revenue for Sarepta Therapeutics. Currently,The company is working hard to expand the drug's range of application.According to relevant news last week, it may soon receive a new product label from the FDA.References:[1]Patient dies in Pfizer’s Phase 2 Duchenne muscular dystrophy trial.Endpoints News.May 7, 2024 04:28 PM EDT.[2]Patient dies in Pfizer study of Duchenne gene therapy.BIOPHARMADIVE.Published May 7, 2024.[3]Pfizer pauses phase 3 dosing in gene therapy trial after young boy's death.By Gabrielle Masson.May 7, 2024 4:29pm.[4]Boy Dosed with Pfizer DMD Gene Therapy Dies a Year after Phase II Trial.By Alex Philippidis.May 7, 2024.[5] Summary of DMD Drug Research Progress. Zhi Ai Progressive Muscular Dystrophy Care Center. 2022-11-21.Scan the WeChat QR code, add the editor of the Biologics Circle, and those who meet the requirements can join.Biological Products WeChat Group! Please indicate: Name + Research Direction! 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