Sickle Cell Anemia and Beta Thalassemia

Busulfan may be an important component in CRISPR technology as a conditioning agent to remove diseased cells prior to CRISPR gene editing.

A new medical breakthrough gives promise to sickle cell anemia and thalassemia patients using CRISPR-Cas 9 technology, a gene editing technology, with IV busulfan as a conditioning agent. In 2020, CRISPR-Cas 9 received recognition when Jennifer Doudna and Emmanuelle Charpentier received the Nobel Prize in Chemistry for their work in this field of technology. There are now treatments using this technology in late-stage clinical trials in the United States.

Instead of using CRISPR to replace the mutated gene with a healthy copy, biopharmaceutical startups have used genome editing to alter the gene-regulation machinery that normally switches off another hemoglobin-encoding gene early in fetal development. This procedure provides enough healthy, alternative hemoglobin to compensate for the mutation. In November 2020, CRISPR Therapeutics demonstrated early success from their CTX001 candidate, CTX001, which delivers CRISPR-Cas9 to hematopoietic stem cells via electroporation. After a patient’s own hematopoietic stem cells are chemically eliminated with busulfan, the CRISPR-edited stem cells are infused back into the patient. The patients treated with CTX001 no longer depended on transfusions for the treatment of their β- thalassemia or sickle-cell disease.