UCLA

Chronic granulomatous disease (CGD) is a severe monogenic immunodeficiency caused by damaging variants in genes required for microbicidal NADPH oxidase activity. Autosomal recessive p47^phox-deficient CGD (p47-CGD) is predominantly caused by a two-nucleotide deletion in exon 2 (delGT) of NCF1. We developed PM359, an autologous CD34+ hematopoietic stem-cell therapy in which prime editing is used to correct delGT. Two participants received PM359 after myeloid conditioning with busulfan: neutrophils and platelets engrafted promptly in both patients. Adverse events were consistent with myeloid conditioning with busulfan. NADPH oxidase activity was observed in neutrophils within 1 month and was maintained for 6 months and 4 months as of the last follow-up visit in Participants 1 and 2, respectively. These results support further investigation of prime editing of CD34+ cells to treat p47-CGD. (Funded by Prime Medicine; ClinicalTrials.gov number, NCT06559176.).