The longest-tracked patients who received Casgevy, the world's first approved CRISPR gene-editing therapy for sickle cell disease, have now gone more than five and a half years without a vaso-occlusive crisis — the agonizing pain episodes that define the condition. [1]

Data presented at the European Hematology Association congress and the American Society of Hematology meeting show that 100 percent of the 45 evaluable patients (those with at least 16 months of follow-up) achieved freedom from hospitalization for severe crises for at least 12 consecutive months. [1] The mean crisis-free duration now exceeds 35 months, with the longest extending past 67 months.

Vertex Pharmaceuticals, which co-developed Casgevy with CRISPR Therapeutics, expects to file for an expanded label in children aged 5 to 11 in the first half of 2026, after Phase 3 data in younger patients showed consistent results. [2] Revenue for the therapy reached $115.8 million in 2025, up from just $10 million in its first full year. About 90 percent of U.S. patients now have reimbursed insurance access. [2]

The therapy works by editing a patient's own stem cells to boost fetal hemoglobin production, which prevents the sickling that causes crises. It requires a one-time infusion after chemotherapy conditioning — a difficult journey, but one that appears to produce lasting results.

For a disease that affects roughly 100,000 Americans, the word "durable" has never sounded so good.

-- KENJI NAKAMURA, Tokyo