Exagamglogene autotemcel (exa-cel), a CRISPR-Cas9 gene editing therapy developed by Vertex Pharmaceuticals and CRISPR Therapeutics, continues to demonstrate durable clinical benefits for patients with severe sickle cell disease (SCD). Updated data from the ongoing Phase 3 CLIMB SCD-121 study, presented at the 66th American Society of Hematology (ASH) Annual Meeting and Exposition, highlight the therapy's effectiveness in preventing vaso-occlusive events (VOCs) and hospitalizations.
The study, led by Haydar Frangoul, MD, MS, Medical Director, Pediatric Hematology/Oncology, Sarah Cannon Pediatric Transplant and Cellular Therapy Program, TriStar Centennial, and Investigator, Sarah Cannon Research Institute, evaluated exa-cel in patients aged 12 years and older with severe SCD. Exa-cel works by reactivating fetal hemoglobin (HbF), offering a potential one-time curative approach for the disease.
Key Findings from CLIMB SCD-121
Frangoul presented data showing that over 90% of participants remained free of VOCs, a hallmark of SCD characterized by severe pain and organ damage. Furthermore, the therapy demonstrated a greater than 90% prevention rate for hospitalizations related to SCD. These benefits were sustained, with participants maintaining HbF levels above 40% for up to five years.
"I keep telling people that our therapy was CRISPR gene editing 1.0 and I'm pretty sure as the field evolves, we are going to potentially use safer conditioning regimen for patients that will does not cause hair loss and infertility. But we had to start somewhere… and I think that's why it's so groundbreaking, is what we did is we established the bar, and now it can only get better from here," Frangoul told HCPLive®.
Long-Term Impact and Future Directions
While the prevention of VOCs is a significant achievement, Frangoul emphasized the importance of assessing exa-cel's long-term impact on preventing end-organ damage, a common complication of SCD. "The big question that yet to be answered is, yes, we are preventing VOCs, but how is that going to impact the end organ damage that we know SCD patients will develop years and years and years down the road. So, I am very excited to see where the field goes," he noted.
Exa-cel, marketed as Casgevy, received FDA approval in late 2023 as a one-time treatment for severe SCD. The ongoing CLIMB SCD-121 trial continues to monitor the safety and efficacy of exa-cel, providing valuable insights into the long-term outcomes of this innovative gene editing therapy.
