Early Results Are Positive for Experimental CRISPR Therapies

Two clinical trial participants—one with β-thalassemia and one with sickle cell disease—appeared to benefit from the gene-editing treatments with minimal side effects, according to the companies.

Written byJef Akst

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ABOVE: Red blood cells with the sickle-cell phenotype
© ISTOCK.COM, IVAN MATTIOLI

The first patients in each of two early-stage clinical trials testing CRISPR-based treatments for inherited blood disorders have been symptom free for several months with normalized hemoglobin levels, the companies developing the therapies announced today (November 19). Both participants experienced only treatable, temporary side effects, according to the data.

Last fall, Switzerland-headquartered CRISPR Therapeutics and Vertex Pharmaceuticals in Boston teamed up to launch a trial in Germany testing a CRISPR-based approach to treating β-thalassemia. The therapy, known as CTX001, is applied to blood stem cells removed from the patient to cleave the BCL11A gene that represses the production of fetal hemoglobin. These cells are then reinfused to provide a healthy supply this protein, normally only produced in infancy, to overcome problems associated with mutations in the gene encoding the adult version. A few months later, the two companies launched ...

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Meet the Author

Jef Akst
Jef (an unusual nickname for Jennifer) got her master’s degree from Indiana University in April 2009 studying the mating behavior of seahorses. After four years of diving off the Gulf Coast of Tampa and performing behavioral experiments at the Tennessee Aquarium in Chattanooga, she left research to pursue a career in science writing. As The Scientist's managing editor, Jef edited features and oversaw the production of the TS Digest and quarterly print magazine. In 2022, her feature on uterus transplantation earned first place in the trade category of the Awards for Excellence in Health Care Journalism. She is a member of the National Association of Science Writers.
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