Search

Sickle cell disease (SCD) is a widespread genetic disease associated with severe disability and multi-organ damage, resulting in a reduced life expectancy. None of the existing clinical treatments provide a solution for all patients. Gene therapy and fetal haemoglobin (HbF) reactivation through genetic approaches have obtained promising, but early, results in patients. Furthermore, the search for active molecules to increase HbF is still ongoing. The delta-globin gene produces the delta-globin of haemoglobin A2 (HbA2). Although expressed at a low level, HbA2 is fully functional and could be a valid anti-sickling agent in SCD. To evaluate the therapeutic potential of a strategy aimed to over-express the delta-globin gene in vivo, we crossed transgenic mice carrying a single copy of the delta-globin gene, genetically modified to be expressed at a higher level (activated), with a humanised mouse model of SCD. The activated delta-globin gene gives rise to a consistent production of HbA2, effectively improving the SCD phenotype. For the first time in vivo, these results demonstrate the therapeutic potential of delta-globin, which could lead to novel approaches to the cure of SCD.

Summary As a result of the anti-tumour activity observed in vitro and in vivo with combined anti-CD20 and anti-CD74 antibodies, we initiated a phase I/II trial of veltuzumab and milatuzumab in patients with relapsed or refractory B-cell non-Hodgkin lymphoma (NHL). Patients received an induction of veltuzumab 200 mg/m2 weekly combined with escalating doses of milatuzumab at 8, 16 and 20 mg/kg weekly for 4 weeks. Patients without disease progression could receive an extended induction with treatment on weeks 12, 20, 28 and 36. A total of 35 patients enrolled on the study. Median age was 63 years, median number of prior therapies was 3, and 63% of patients were rituximab refractory. No dose-limiting toxicities were observed in the phase I study. Related grade 3–4 toxicities included lymphopenia, leucopenia, neutropenia, anaemia, infusion reactions, hyperglycaemia, fatigue and atrial tachycardia. Median weeks of therapy was 12 and 29% of patients completed all 36 weeks of therapy. The overall response rate was 24%, median duration of response was 12 months, and responses were observed at all dose levels and in 50% of patients refractory to rituximab. Combination therapy with veltuzumab and milatuzumab demonstrated activity in a population of heavily pre-treated patients with relapsed or refractory indolent NHL.

KLF1/EKLF and related Krueppel-like factors (KLFs) are variably implicated in the regulation of the HBB-like globin genes. Prompted by the observation that four KLF sites are distributed in the human alpha-globin gene (HBA) promoter, we investigated if KLFs could also act to modulate the expression of the HBA genes. Among the KLFs tested, only KLF4/GKLF bound specifically to three out of four alpha-globin KLF sites. The occupancy of the same sites by KLF4 in vivo was confirmed by chromatin immunoprecipitation assays with KLF4-specific antibodies. In luciferase reporter assays in MEL cells, high levels of the wild type HBA promoter, but not mutated promoters bearing point mutations that disrupted KLF4-DNA binding, were transactivated by over-expression of KLF4. In K562 cells, induced KLF4 expression with a Tet-off regulated cassette stimulated the expression of the endogenous HBA genes. In a complementary assay in the same cell line, knocking down KLF4 with lentiviral delivered sh-RNAs caused a parallel decrease in the transcription of the HBA genes. All experiments combined support a regulatory role of KLF4 in the control of HBA gene expression.

Cutaneous T-cell lymphomas (CTCL) are a heterogeneous group of malignancies derived from skin-homing T cells. The most common forms of CTCL are Mycosis Fungoides (MF) and Sezary Syndrome (SS). Accurate diagnosis remains a challenge due to the heterogeneity of presentation and the lack of highly characteristic immunophenotypical and genetic markers. Over the past decade molecular studies have improved our understanding of the biology of CTCL. The identification of gene expression differences between normal and malignant T-cells has led to promising new diagnostic and prognostic biomarkers that now need validation to be incorporated into clinical practice. These biomarkers may also provide insight into the mechanism of development of CTCL. Additionally, treatment options have expanded with the approval of new agents, such as histone deacetylase inhibitors. A better understanding of the cell biology, immunology and genetics underlying the development and progression of CTCL will allow the design of more rational treatment strategies for these malignancies. This review summarizes the clinical epidemiology, staging and natural history of MF and SS; discusses the immunopathogenesis of MF and the functional role of the malignant T-cells; and reviews the latest advances in MF and SS treatment.

The transcription factor erythroid Kruppel-like factor (EKLF) specifically activates the beta-globin gene by interacting with the proximal beta-globin CACCC box, a known hot spot for thalassaemia mutations. This study investigated whether EKLF could also bind to, and activate from, the distal CACCC, which is a rare site of thalassaemia mutations. Using band shift and transient expression analysis with wild type, single and double CACCC mutants, we established that the distal CACCC box is weakly bound by EKLF, but, when mutated, significantly impairs EKLF-dependent beta-globin stimulation. Thus, EKLF requires both CACCC boxes to maximally stimulate the beta-globin gene.

KLF1/EKLF and related Krueppel-like factors (KLFs) are variably implicated in the regulation of the HBB-like globin genes. Prompted by the observation that four KLF sites are distributed in the human alpha-globin gene (HBA) promoter, we investigated if KLFs could also act to modulate the expression of the HBA genes. Among the KLFs tested, only KLF4/GKLF bound specifically to three out of four alpha-globin KLF sites. The occupancy of the same sites by KLF4 in vivo was confirmed by chromatin immunoprecipitation assays with KLF4-specific antibodies. In luciferase reporter assays in MEL cells, high levels of the wild type HBA promoter, but not mutated promoters bearing point mutations that disrupted KLF4-DNA binding, were transactivated by over-expression of KLF4. In K562 cells, induced KLF4 expression with a Tet-off regulated cassette stimulated the expression of the endogenous HBA genes. In a complementary assay in the same cell line, knocking down KLF4 with lentiviral delivered sh-RNAs caused a parallel decrease in the transcription of the HBA genes. All experiments combined support a regulatory role of KLF4 in the control of HBA gene expression.

The transcription factor erythroid Kruppel-like factor (EKLF) specifically activates the beta-globin gene by interacting with the proximal beta-globin CACCC box, a known hot spot for thalassaemia mutations. This study investigated whether EKLF could also bind to, and activate from, the distal CACCC, which is a rare site of thalassaemia mutations. Using band shift and transient expression analysis with wild type, single and double CACCC mutants, we established that the distal CACCC box is weakly bound by EKLF, but, when mutated, significantly impairs EKLF-dependent beta-globin stimulation. Thus, EKLF requires both CACCC boxes to maximally stimulate the beta-globin gene.

The clinical and laboratory data of 48 leukapheresis-treated patients with hyperleucocytic leukaemia (HL) was reviewed to assess the correlation between the degree of leucoreduction and early mortality. Leukapheresis resulted in > 50% leucoreductions and postapheresis WBC counts < 100 x 10(9)/l in most patients (64.5%). Patients presenting with neurological, respiratory or renal complications had higher early mortality rates than patients without such complications, despite similar initial WBC counts and comparable leucoreductions. Thus, in these patients, more efficient leucoreduction was not associated with improved early survival.

We have evaluated the possibility of enhancing the cell killing effect of ara-C on AML blasts by increasing their proliferative activity with haemopoietic growth factors. Leukaemic cells from 10 AML patients were incubated for 3 d in liquid culture in the presence or in the absence of the human recombinant growth factors IL-1 beta (5 U/ml) and IL-3 (3 U/ml), and subsequently exposed to ara-C (3 micrograms/ml) for the last 24 h. The number of residual leukaemic stem cells was evaluated by a clonogenic assay in semisolid medium. The results showed that ara-C exposure inhibits the proliferation of a higher proportion of clonogenic cells in cultures pretreated with growth factors than in the controls (mean inhibitory values: in the absence of growth factors = 49.8%; with IL-1 beta = 58.3%; with IL-3 78.9%). The effect was statistically significant only when IL-3 was used as a growth factor. The results suggest that haemopoietic growth factors may help to improve the therapeutic index of cytostatic agents.