Exagamglogene autotemcel — Drug Monograph
Brand names: Casgevy
Drug class: Other
Mechanism of Action
Casgevy is the world's first approved CRISPR-Cas9–based medicine. It is an autologous, ex vivo CRISPR-Cas9–edited CD34+ hematopoietic stem and progenitor cell (HSPC) therapy. Patient-derived HSPCs are edited using a CRISPR-Cas9 ribonucleoprotein complex that creates a double-strand break at the BCL11A erythroid enhancer — a region that suppresses fetal hemoglobin (HbF, γ-globin) expression after birth. Disruption of this enhancer permanently and heritably reduces BCL11A expression in erythroid lineage cells, de-repressing HbF production. The resulting high levels of HbF (≥20–30 pg/cell in…
FDA Indications
- Sickle cell disease (SCD) with recurrent vaso-occlusive crises (VOCs) — patients aged 2 years and older (FDA approved December 8, 2023 for ages 12+; expanded July 1, 2026 to ages 2+)
- Transfusion-dependent β-thalassemia (TDT) — patients aged 2 years and older (FDA approved December 8, 2023 for ages 12+; expanded July 1, 2026 to ages 2+)
Common Side Effects
- Oral mucositis (from busulfan conditioning)
- Febrile neutropenia (expected during engraftment period)
- Nausea, vomiting (conditioning-related)
- Headache
- Fatigue
- Alopecia (conditioning-related)
- Musculoskeletal pain during HSPC mobilization
Clinical Pearl
Casgevy is a landmark — the first CRISPR-Cas9 medicine approved anywhere in the world (UK Dec 2023, US Dec 2023). In the pivotal CLIMB-SCD-121 trial (SCD), 93.5% of evaluable patients were free from severe VOC episodes for at least 12 consecutive months. In CLIMB-THAL-111 (TDT), 89.6% achieved transfusion independence for ≥12 months. The July 2026 FDA expansion to ages 2+ is transformative — treating children before cumulative organ damage from SCD occurs. The critical practical consideration:…