Beam Therapeutics Reports Promising Long-Term Data for Base-Edited Sickle Cell Therapy Risto-cel
Key Insights
Beam Therapeutics presented updated data from 31 patients in the BEACON Phase 1/2 trial showing risto-cel (search) achieved mean hemoglobin F levels above 60% and reduced pathologic hemoglobin S below 40% for up to 20 months.
The base-edited cell therapy demonstrated efficient manufacturing with patients requiring a median of only one stem cell collection cycle and rapid engraftment with median neutrophil recovery in 17.5 days.
No patients experienced severe vaso-occlusive crises (search) post-engraftment, and all patients achieved resolution of anemia (search) with normalized hemolysis markers following treatment.
Beam Therapeutics announced updated safety and efficacy data from its BEACON Phase 1/2 clinical trial of ristoglogene autogetemcel (search) (risto-cel (search)) at the 67th American Society of Hematology Annual Meeting, demonstrating sustained clinical benefits in patients with severe sickle cell disease (search). The data, based on 31 adult and adolescent patients with follow-up ranging from 0.3 to 20.4 months, reinforce the potential of base editing as a precision genetic medicine approach.
Sustained Hemoglobin Improvements Drive Clinical Benefits
The therapy achieved mean hemoglobin F (HbF) levels above 60% and sustained reductions in pathologic hemoglobin S (HbS) below 40%, consistent with previously reported data from the European Hematology Association 2025 Congress. Patients demonstrated a pancellular distribution of HbF across most circulating red blood cells, with mean per-cell HbF levels maintained above the sickling threshold throughout follow-up.
"With a growing dataset and longer follow up, these updated data continue to underscore the potential of risto-cel (search) to make a transformative difference in the lives of patients with SCD," said Ashish Gupta, M.D., MPH, from the University of Minnesota.
All patients experienced resolution of anemia (search) after elimination of transfused blood, with total hemoglobin levels increasing rapidly. Key markers of hemolysis, including indirect bilirubin, haptoglobin, lactate dehydrogenase, and reticulocytes, normalized or improved in all patients following treatment. Erythropoietin levels also trended toward normal, indicating significant improvement in oxygen delivery to tissues.
Efficient Manufacturing and Rapid Engraftment
The base editing approach demonstrated manufacturing advantages over traditional gene therapy approaches. Patients required a median of one stem cell collection cycle, comprising a median of three total collection days for manufacturing and backup cell collection. The efficient cell collection and manufacturing processes, combined with high, predictable yields from base editing, resulted in streamlined treatment logistics.
Patients achieved rapid bone marrow reconstitution post-treatment, with median time to neutrophil engraftment of 17.5 days and median duration of severe neutropenia of only seven days. Median time to platelet engraftment was 19 days, and notably, 29% of patients did not require any platelet transfusions following treatment.
Strong Safety Profile and Clinical Outcomes
No patients experienced investigator-reported severe vaso-occlusive crises (search) post-engraftment, representing a significant clinical milestone for this patient population. The safety profile remained consistent with busulfan conditioning and autologous hematopoietic stem cell transplantation, with the most common treatment-emergent adverse events including stomatitis, febrile neutropenia, and decreased appetite.
One patient death occurred four months after infusion due to respiratory failure, which investigators determined was likely related to busulfan conditioning and unrelated to risto-cel (search) itself.
Durable Editing Efficiency
The therapy demonstrated sustained editing efficiency in both peripheral blood and bone marrow. Mean peripheral blood editing reached 67.4% at month 6 and increased to 72.8% by month 12, indicating durable genetic modification.
Optimized Cell Collection Protocol
Beam also presented data showing that a tiered fixed-dose plerixafor mobilization regimen led to higher CD34+ (search) cell yields, faster collection, and fewer collection cycles compared to traditional weight-based dosing. The fixed-dose regimen demonstrated greater efficiency in stem cell collection while maintaining a comparable safety profile.
"Risto-cel (search) continues to demonstrate how base editing can fulfill its promise as a next-generation precision genetic medicine that could significantly improve the treatment process and outcomes for patients with SCD," said John Evans, chief executive officer of Beam Therapeutics.
About the Therapy and Disease
Risto-cel (search) consists of autologous CD34+ (search) hematopoietic stem and progenitor cells that have been base-edited in the promoter regions of the HBG1/2 (search) genes. The edit is designed to inhibit the transcriptional repressor BCL11A (search) from binding to the promoter without disrupting BCL11A expression, leading to increased production of non-sickling fetal hemoglobin.
Sickle cell disease (search) affects an estimated 100,000 individuals in the United States and approximately eight million people worldwide. The disease is caused by a single point mutation in the beta globin gene, resulting in sickled red blood cells that obstruct blood vessels and cause severe complications including anemia (search), pain crises, infections, stroke, and organ failure.