Technology & Medicine › Internet, genomes & AI › CRISPR gene editing
First approved CRISPR therapy (Casgevy)
November 2023 (UK); December 2023 (US)· Invention or discovery· Germs, drugs & genetics
Well documentedSolid records, physical evidence or scientific consensus.
The first approved medicine made with CRISPR gene editing, a one-time treatment for sickle cell disease and beta thalassemia.
See it on the Technology & Medicine map →How it works
Sickle cell disease is an inherited blood disorder in which faulty hemoglobin bends red cells into sickles that block vessels, causing pain and early death. Casgevy, from Vertex and CRISPR Therapeutics, takes a patient's blood stem cells, uses CRISPR to switch on fetal hemoglobin, a backup version the body normally turns off after birth, and returns them after chemotherapy clears the marrow. Britain approved it in November 2023, the US in December.
Why it mattered
It was the first approved CRISPR medicine and a functional cure for many patients, though its US price of about $2.2 million limits access.
Think of it like
Rather than repairing a broken boiler, it turns back on a spare boiler that was shut off at birth.
How we know
Trials in which 29 of 31 evaluated sickle-cell patients went at least a year without severe pain crises; UK and US approval records; first patient Victoria Gray's documented case.
Still unknown or debated
Long-term safety, whether the edits cause hidden DNA damage, and how to reach patients in Africa and India, where most live, remain open questions.
Connections (2)
▸Genetic engineering (recombinant DNA) set the stage for gene therapies like the First approved CRISPR therapy (Casgevy)Mostly agreed
The connection
Recombinant DNA gave medicine the tools to put new or corrected genes into patients' cells, launching gene therapy trials in 1990. Early efforts used viruses to add genes and suffered setbacks, including a patient's death in 1999. Casgevy follows the same plan of modifying patients' cells outside the body, but uses CRISPR to edit them precisely.
When and how
First approved gene therapy trial at the US National Institutes of Health, 1990; Jesse Gelsinger's death in a Philadelphia trial, 1999; Casgevy approved in Britain and the US, 2023.
How sure are we?
The lineage is documented in medical literature: Casgevy uses the same remove, modify and return approach as earlier cell-based gene therapies.
Debates and open questions
Whether editing genes inside the body, rather than removing cells, will make such therapies cheaper and available worldwide is still being tested.
▸CRISPR gene editing led to the First approved CRISPR therapy (Casgevy)Well documented
The connection
Casgevy uses CRISPR-Cas9 to cut one spot in patients' blood stem cells: a switch region of the BCL11A gene that normally shuts off fetal hemoglobin after birth. Disabling it lets red cells make healthy fetal hemoglobin again. It reached approval about 11 years after the 2012 CRISPR paper, fast for a new kind of medicine.
When and how
CRISPR Therapeutics, co-founded by Emmanuelle Charpentier, with Vertex; first patient Victoria Gray treated in Nashville in July 2019; approvals in late 2023.
How we know
Trial results in the New England Journal of Medicine (2021, 2024) and regulators' approval documents describe the CRISPR editing step.
Debates and open questions
Patients are being followed for 15 years to check that the edits stay safe and effective; rival gene therapies compete for the same patients.