NEJM: Editas Reni-cel (CRISPR-Cas12a) Eliminates Sickle Cell Crises in 27 of 28 Patients in RUBY Trial

The New England Journal of Medicine publishes full Phase 1/2 data from the RUBY trial of renizgamglogene autogedtemcel (reni-cel), Editas Medicine's CRISPR-Cas12a gene-editing therapy for severe sickle cell disease (NCT04853576). In 28 treated patients (median follow-up 9.5 months), 27 of 28 experienced zero vaso-occlusive events (VOEs) after infusion. At six-month follow-up in 18 evaluable patients, mean total hemoglobin rose from 9.8 to 13.8 g/dL and mean fetal hemoglobin (HbF) increased from 2.5% to 48.1%, remaining stable. Blood cell recovery occurred within one month. A companion NEJM paper on the same date reports that all 9 transfusion-dependent beta-thalassemia patients treated with reni-cel achieved transfusion independence. Reni-cel uses CRISPR-AsCas12a (rather than SpCas9 used in Casgevy) to disrupt BCL11A binding sites in HBG1/2 promoters, reactivating fetal hemoglobin production. Editas argues Cas12a produces more precise, reproducible cuts. These results, combined with BEAM-101/risto-cel data published April 1 and Casgevy's 2023–2024 approvals, establish fetal hemoglobin reactivation as a robust therapeutic target with multiple gene-editing approaches in clinical development.