TL;DR
The RUBY trial's two-year data remains durable — 93% of treated sickle cell patients are transfusion-free with no late relapses.
MSM Perspective
Medical press continues to cover the NEJM results as a milestone but has not revisited the access gap.
X Perspective
Gene therapy advocates on X call the durability data the strongest evidence yet that CRISPR cures are permanent.
The numbers from the RUBY trial have not moved, which is the point. As this paper detailed yesterday, twenty-seven of twenty-eight patients in the initial cohort experienced zero vaso-occlusive crises after a single CRISPR-Cas12a infusion. At two years of follow-up, 93 percent of the expanded forty-patient group remain transfusion-free, with hemoglobin levels holding at a mean of 13.8 g/dL — squarely normal [1].
No late relapses have been observed. The two patients who experienced crises did so in the first six months, suggesting that the protective effect strengthens as edited stem cells fully repopulate bone marrow [1]. Fetal hemoglobin levels have remained stable above 40 percent of total hemoglobin across the cohort.
The clinical question is shifting from whether the therapy works to how long the cure lasts. Two years of durable remission in a disease with a median life expectancy of forty-five years is significant but not yet definitive. Editas Medicine is continuing follow-up, and the FDA's eventual review will weigh durability heavily [2].
The access question — who can reach a $2-3 million autologous cell therapy requiring myeloablative conditioning — remains unanswered. Twenty million people worldwide have sickle cell disease. Forty have been treated. The science is solved. The logistics are not.
-- KENJI NAKAMURA, Tokyo
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