CRISPR Therapeutics (NASDAQ:CRSP) and collaboration partner Vertex Pharmaceuticals (NASDAQ:VRTX) announce new interim data from two clinical trials evaluating CRISPR/Cas9 gene-editing therapy in patients with transfusion-dependent beta thalassemia (TDT) and severe sickle cell disease (SCD). The results were virtually presented at the European Hematology Association (EHA) Congress.

Phase 1/2 CLIMB-111 study evaluating CTX001 in TDT: Patient #1, with the β0/IVS-I-110 genotype, required 34 units of packed red blood cells each year before enrollment. The patient achieved neutrophil engraftment 33 days after CTX001 infusion and achieved platelet engraftment in 37 days. The patient was transfusion-independent at month 15 post-treatment.

Patient #2, with the β0/IVS-II-745 genotype, required 61 units of packed red blood cells each year. After infusion with CTX001, neutrophil and platelet engraftment occurred in 36 days and 34 days, respectively. The patient remained transfusion-independent five months post-treatment.

Phase 1/2 CLIMB-121 study evaluating CTX001 in SCD: Patient #1 experienced seven vasco-occlusive crises (VOCs) and five transfusions of packed red blood cells each of the prior two years before enrollment. Full neutrophil and platelet engraftment achieved in 30 days post-infusion. At month 9, the patient was VOC-free and transfusion-independent.

Both studies are ongoing. Dosing being re-initiated at certain sites where the studies were temporarily paused due to COVID-19.

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