In vivo selection of genetically modified erythroblastic progenitors leads to long-term correction of β-thalassemia

Gene therapy for β-thalassemia requires stable transfer of a β-globin gene into hematopoietic stem cells (HSCs) and high and regulated hemoglobin expression in the erythroblastic progeny. We developed an erythroid-specific lentiviral vector driving the expression of the human β-globin gene from a minimal promoter/enhancer element containing two hypersensitive sites from the β-globin locus control region. Transplantation of transduced HSCs into thalassemic mice leads to stable and long-term correction of anemia with all red blood cells expressing the transgene. A frequency of 30–50% of transduced HSCs, harboring an average vector copy number per cell of 1, was sufficient to fully correct the thalassemic phenotype. In the mouse model of Cooley's anemia transplantation of transduced cells rescues lethality, leading to either a normal or a thalassemia intermedia phenotype. We show that genetically corrected erythroblasts undergo in vivo selection with preferential survival of progenitors harboring proviral integrations in genome sites more favorable to high levels of vector-derived expression. These data provide a rationale for a gene therapy approach to β-thalassemia based on partially myeloablative transplantation protocols

Phase I study of the gamma secretase inhibitor PF-03084014 in combination with docetaxel in patients with advanced triplenegative breast cancer

Background: The NOTCH signaling pathway may be involved in the survival of stem cell-like tumor-initiating cells and contribute to tumor growth. In this phase Ib, open-label, multicenter study (NCT01876251), we evaluated PF-03084014, a selective gamma-secretase inhibitor in patients with advanced triple-negative breast cancer. Methods: The dose-finding part was based on a 2×3 matrix design using the modified toxicity probability interval method. Oral PF-03084014 was administered twice daily continuously in combination with intravenous docetaxel given on day 1 of each 21-day cycle. Primary endpoint was first-cycle dose-limiting toxicity (DLT) for the dose-finding part and 6-month progression-free survival (PFS) for the expansion cohort treated at the maximum tolerated dose (MTD). Secondary endpoints included safety, objective response, and pharmacokinetics of the combination. Results and Conclusions: The MTD was estimated to be PF-03084014 100 mg twice daily / docetaxel 75 mg/m2. At this dose level, combination treatment was generally well tolerated (one DLT, grade 3 diarrhea, among eight DLT-evaluable patients). The most common all-grade, treatment-related adverse events reported in all patients (N = 29) were neutropenia (90%), fatigue (79%), nausea (72%), leukopenia (69%), diarrhea (59%), alopecia (55%), anemia (55%), and vomiting (48%). No effect was observed on the pharmacokinetics of docetaxel when administered in combination with PF-03084014. Four (16%) of 25 response-evaluable patients achieved a confirmed partial response; nine (36%) patients had stable disease, including five patients with unconfirmed partial response. In the expansion cohort, median PFS was 4.1 (95% CI 1.3-8.1) months (6-month PFS rate 17.1% [95% CI 0.8-52.6%]).SCOPUS: ar.jinfo:eu-repo/semantics/publishe