Crispr therapeutics and vertex announce positive safety and efficacy data from first two patients treated with investigational crispr/cas9 gene-editing therapy ctx001® for severe hemoglobinopathies

Crispr therapeutics and vertex pharmaceuticals incorporated announced positive, interim data from the first two patients with severe hemoglobinopathies treated with the investigational crispr/cas9 gene-editing therapy ctx001 in ongoing phase 1/2 clinical trials. one patient with transfusion-dependent beta thalassemia (tdt) received ctx001 in the first quarter of 2019 and data for this patient reflect nine months of safety and efficacy follow-up. one patient with severe sickle cell disease (scd) received ctx001 in mid-2019 and data for this patient reflect four months of safety and efficacy follow-up. these studies are ongoing and patients will be followed for approximately two years following infusion. several additional patients have been enrolled and have had drug product manufactured across the two studies. the patient with tdt has the ss0/ivs-i-110 genotype and required 16.5 transfusions per year (annualized rate during the two years prior to consenting for the study) before enrolling in the clinical study. the patient achieved neutrophil engraftment 33 days after ctx001 infusion and platelet engraftment 37 days after infusion. two serious adverse events (saes) occurred, neither of which the principal investigator (pi) considered related to ctx001: pneumonia in the presence of neutropenia and veno-occlusive liver disease attributed to busulfan conditioning; both subsequently resolved. at nine months after ctx001 infusion, the patient was transfusion independent and had total hemoglobin levels of 11.9 g/dl, 10.1 g/dl fetal hemoglobin, and 99.8% f-cells (erythrocytes expressing fetal hemoglobin). the patient with scd experienced seven vaso-occlusive crises (vocs) per year (annualized rate during the two years prior to consenting for the study) before enrolling in the clinical study. the patient achieved neutrophil and platelet engraftment 30 days after ctx001 infusion. three saes occurred, none of which the pi considered related to ctx001: sepsis in the presence of neutropenia, cholelithiasis, and abdominal pain, all of which resolved. at four months after ctx001 infusion, the patient was free of vocs and had total hemoglobin levels of 11.3 g/dl, 46.6% fetal hemoglobin, and 94.7% f-cells (erythrocytes expressing fetal hemoglobin). the ongoing phase 1/2 open-label trial, climb-thal-111, is designed to assess the safety and efficacy of a single dose of ctx001 in patients ages 18 to 35 with tdt. the study will enroll up to 45 patients and follow patients for approximately two years after infusion. each patient will be asked to participate in a long-term follow-up study. enrollment is ongoing at six clinical trial sites in the united states, canada and europe. the ongoing phase 1/2 open-label trial, climb-scd-121, is designed to assess the safety and efficacy of a single dose of ctx001 in patients ages 18 to 35 with severe scd. the study will enroll up to 45 patients and follow patients for approximately two years after infusion. each patient will be asked to participate in a long-term follow-up study. enrollment is ongoing at 12 clinical trial sites in the united states, canada and europe.
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