by Ana Ramirez
Editorial Disclaimer
The views expressed represent the author’s interpretation of current scientific evidence and do not constitute medical advice. Readers are encouraged to consult qualified medical professionals and primary literature for clinical guidance.
The field of genome editing has rapidly shifted from experimental molecular biology to clinically validated medicine, largely driven by CRISPR-Cas9. What began as a bacterial adaptive immune system has now become one of the most powerful tools for treating genetic disease, engineering immune cells, and developing diagnostic technologies. In recent years, multiple human clinical trials and regulatory approvals have demonstrated that CRISPR is no longer theoretical, it is entering real-world medicine.
First approved CRISPR therapy in human disease
A landmark development in genomic medicine is the approval of extraglomogene autotemcel (Casgevy), the first CRISPR-based therapy approved for clinical use in humans. It was developed by Vertex Pharmaceuticals in collaboration with CRISPR Therapeutics.
This therapy uses ex vivo editing of patient hematopoietic stem cells to disrupt the BCL11A enhancer, leading to reactivation of fetal hemoglobin production. Clinically, this compensates for defective adult hemoglobin in sickle cell disease and ?-thalassemia.
Clinical trial results have shown that most treated patients achieve elimination or major reduction of vaso-occlusive crises and transfusion dependence, representing one of the strongest demonstrations of durable therapeutic genome editing.
In vivo CRISPR therapy for systemic disease
Another major advance is the development of in vivo genome editing, where CRISPR components are delivered directly into the body rather than modifying cells externally.
A key example is NTLA-2001, developed by Intellia Therapeutics. This therapy targets the TTR gene in hepatocytes using lipid nanoparticle delivery systems to treat transthyretin (ATTR) amyloidosis.
Clinical data show significant and sustained reductions in serum transthyretin protein levels after a single infusion, suggesting long-term therapeutic potential from a one-time gene editing intervention.
CRISPR in inherited retinal disease
Gene editing is also being explored in ophthalmology for previously untreatable genetic blindness. One major clinical program is EDIT-101, developed by Editas Medicine.
This therapy targets the CEP290 mutation responsible for Leber congenital amaurosis type 10 (LCA10). Delivered via subretinal injection, CRISPR-Cas9 is used to excise a pathogenic DNA sequence directly in retinal cells.
Early clinical trial findings have reported partial improvements in visual function in some patients, indicating potential for functional restoration in inherited blindness.
CRISPR-engineered cancer immunotherapy
CRISPR technology is increasingly being used in oncology to enhance immune cell function and overcome tumor resistance. In early clinical trials, researchers have used CRISPR to engineer T cells for improved tumor recognition and persistence.
One of the first human studies of CRISPR-edited T cells was reported in patients with advanced cancers, demonstrating feasibility and acceptable safety profiles. These studies include gene knockouts that enhance immune activity and improve CAR-T cell performance.
Although still experimental, these approaches are expanding rapidly, particularly for solid tumors, which remain difficult to treat with conventional CAR-T therapies.
References
- Frangoul et al., New England Journal of Medicine (2021), “CRISPR-Cas9 Gene Editing for Sickle Cell Disease and ß-Thalassemia”
- U.S. FDA & MHRA regulatory approvals (2023-2024 updates)
- Gillmore et al., New England Journal of Medicine (2021), “In Vivo CRISPR-Cas9 Genome Editing for Transthyretin Amyloidosis”
- Intellia Therapeutics NTLA-2001 Phase 1 clinical trial updates (2021-2024)
- Maeder et al., Nature Medicine (2019), preclinical development of EDIT-101
- Editas Medicine Phase 1/2 clinical trial reports (2020-2023)
- Stadtmauer et al., Science (2020), “CRISPR-Engineered T Cells in Cancer Patients”
- ClinicalTrials.gov Identifier: NCT03399448
About the Author
Ana is a high school senior passionate about medicine and health, and a regular contributor to science academia, with a focus on the evolving fields of genetics and cellular biology.