Vertex Showcases Long-Term Durability and Consistency of Casgevy

At the recent European Hematology Association (EHA) conference, Vertex Pharmaceuticals unveiled compelling long-term data regarding the efficacy and durability of its gene therapy, Casgevy. This therapy, a pioneering treatment developed using CRISPR gene editing technology, targets patients suffering from sickle cell disease (SCD) and transfusion-dependent beta thalassemia (TDT).

Six months following the U.S. Food and Drug Administration's (FDA) groundbreaking approval of Casgevy for SCD, Vertex’s data reveal promising results. Among 39 SCD patients who received the gene therapy and were followed for at least 16 months, a remarkable 92%—or 36 individuals—experienced no vaso-occlusive crises (VOCs) for a minimum of 12 consecutive months. VOCs are severe pain episodes characteristic of SCD. On average, patients remained VOC-free for 28 months, with one patient reaching an impressive 55 months without a crisis. Furthermore, almost all these patients avoided hospitalization due to VOCs for at least 12 consecutive months, aligning with the trial’s previously reported primary and secondary endpoints.

In parallel to the SCD findings, Vertex also presented data for TDT patients treated with Casgevy. Five months after the FDA’s approval for this indication, the results were equally promising. Out of 52 TDT patients with a follow-up of at least 16 months, 94%—or 49 individuals—achieved transfusion independence for a minimum of 12 consecutive months. The average duration of transfusion independence stood at 31 months, with one patient reaching 59 months. Notably, all participants in the study are now free from transfusions. Of the three patients who initially did not achieve independence, two have been transfusion-free for over a year, and the third patient has been transfusion-independent for four months.

Patients in both the SCD and TDT groups reported "sustained clinically meaningful improvements in their quality of life and functional well-being," according to Vertex. Additionally, the levels of the diagnostic biomarker BCL11A remained stable over time in both bone marrow and peripheral blood, serving as an indicator of successful and enduring gene editing in long-term hematopoietic stem cells.

These robust results are expected to support Vertex’s efforts to obtain marketing authorization for Casgevy in the United Kingdom. Last month, the National Institute for Health and Care Excellence (NICE) in the UK did not recommend Casgevy for commercial use in its draft guidance. In the U.S., the one-time treatment is priced at $2.2 million, while European authorities granted approval in February.

Dr. Franco Locatelli, a professor of pediatrics at the Catholic University of the Sacred Heart of Rome, emphasized the significance of these findings. "The comprehensive data set presented today for adult and adolescent TDT patients adds to the growing body of evidence for Casgevy, and it is important to now ensure the availability of this innovative treatment to patients in the real world," he stated. "With the longest follow-up now more than five years, alongside stable editing and sustained fetal hemoglobin levels, I have conviction in the durable benefit to the patients treated with Casgevy."

In summary, the long-term data presented by Vertex at the EHA conference underscores Casgevy’s potential as a transformative treatment for SCD and TDT, highlighting its ability to provide lasting clinical benefits and significantly improve patients’ quality of life.