Dendritic cell vaccination as postremission treatment to prevent or delay relapse in acute myeloid leukemia

Relapse is a major problem in acute myeloid leukemia (AML) and adversely impacts survival. In this phase II study, we investigated the effect of vaccination with dendritic cells (DCs) electroporated with Wilms’ tumor 1 (WT1) mRNA as post-remission treatment in 30 AML patients at very high risk of relapse. There was a demonstrable anti-leukemic response in 13 patients. Nine patients achieved molecular remission as demonstrated by normalization of WT1 transcript levels, 5 of which are sustained after a median follow-up of 109.4 months. Disease stabilization was achieved in 4 other patients. Five-year overall survival (OS) was higher in responders than in non-responders (53.8% vs. 25.0%; P=0.01). In patients receiving DCs in first complete remission (CR1), there was a vaccine-induced relapse reduction rate of 25% and the 5-year relapse-free survival was higher in responders than in non-responders (50% vs. 7.7%; P65 years who received DCs in CR1, 5-year OS was 69.2% and 30.8% respectively, as compared to 51.7% and 18% in the Swedish Acute Leukemia Registry (SALR). Long-term clinical response was correlated with increased circulating frequencies of poly-epitope WT1-specific CD8+ T-cells. Long-term OS was correlated with interferon-γ+ and tumor necrosis factor-α+ WT1-specific responses in delayed type hypersensitivity-infiltrating CD8+ T-lymphocytes. In conclusion, vaccination of AML patients with WT1 mRNA-electroporated DCs can be an effective strategy to prevent or delay relapse after standard chemotherapy, translating into improved OS rates, which are correlated with the induction of WT1-specific CD8+ T-cell response. This trial was registered at www.clinicaltrials.gov as #NCT00965224

Synthesis of α-amino-lipophosphonates as cationic lipids or co-lipids for DNA transfection in dendritic cells

International audienceCationic lipid/co-lipid combinations have been extensively explored in gene delivery as alternatives to viral vectors. To be established as a gold standard of chemical vectors, considerable improvement in their transfection efficiency is however required. Herein, we report a simple procedure to synthesize new cationic and co-lipids for the DNA transfection of dendritic cells (DCs). Seven α-amino-lipophosphonates featuring two aza-heterocycles with protonable sites (imidazole or pyridine) were synthesized and used as co-lipids in liposomes with cationic lipid. For each liposome, the cationic lipid is either the imidazolium lipophosphoramidate (Lipid 2) or α-amino-lipophosphonate containing basic tertiary aliphatic amine in the polar head group (Lipid 3b). The cationic lipids either with new co-lipids or DOPE formed positively charged nano-sized stable liposomes that effectively interact with plasmide DNA (pDNA) to produce lipoplexes. Membrane fusion studies showed that α-amino-phosphonates featuring imidazole moiety in the polar head group exhibited higher fusion at pH 5.5 than pH 7.4. This study suggests that the best formulations for the transfection of DCs (based on the % transfected cells and the intensity of EGFP-based fluorescence) are Lipid 2 associated with either 3a, 3d or DOPE and the cationic lipid 3b formulated with 3a or DOPE as helper lipid. Furthermore, Lipid 3a could be used as an alternative to DOPE as a helper lipid. Overall, these results indicate that novel imidazole containing α-amino-phosphonates can serve as effective transfection agents for the DC-based vaccines

Evaluation of New Fluorescent Lipophosphoramidates for Gene Transfer and Biodistribution Studies after Systemic Administration

International audienceThe objective of lung gene therapy is to reach the respiratory epithelial cells in order to deliver a functional nucleic acid sequence. To improve the synthetic carrier’s efficacy, knowledge of their biodistribution and elimination pathways, as well as cellular barriers faced, depending on the administration route, is necessary. Indeed, the in vivo fate guides the adaptation of their chemical structure and formulation to increase their transfection capacity while maintaining their tolerance. With this goal, lipidic fluorescent probes were synthesized and formulated with cationic lipophosphoramidate KLN47 (KLN: Karine Le Ny). We found that such formulations present constant compaction properties and similar transfection results without inducing additional cytotoxicity. Next, biodistribution profiles of pegylated and unpegylated lipoplexes were compared after systemic injection in mice. Pegylation of complexes led to a prolonged circulation in the bloodstream, whereas their in vivo bioluminescent expression profiles were similar. Moreover, systemic administration of pegylated lipoplexes resulted in a transient liver toxicity. These results indicate that these new fluorescent compounds could be added into lipoplexes in small amounts without perturbing the transfection capacities of the formulations. Such additional properties allow exploration of the in vivo biodistribution profiles of synthetic carriers as well as the expression intensity of the reporter gene

Glyco-phospho-glycero-ether lipid as modulator of SK3 ion channel and SK3-dependent cancer cell migration

International audienceIn this short review paper, we report our efforts to design new inhibitors of SK3 ion channel that are involved in cancer cell migration and metastases formation. The originality of the new SK3 inhibitors comes from their amphiphilic nature and contrast form others inhibitors that are peptides or heterocyclic compounds. We found that ether lipids and ether phospho-glyco-lipids are indeed efficient to modulate SK3 ion channel that consequently reduced cancer cell migration (in vitro assays) and abolished the formation of bone metastases in a murine model of breast cancer

Synthetic phospholipids and phospho-bola-amphiphiles for nucleic acid delivery

International audienceCationic lipids are widely used as synthetic vectors for gene delivery. In this short review article we report the recent developments dedicated to the synthesis of synthetic cationic phospholipids and neutral phospholipids that are specially designed for gene delivery applications. These cationic lipids that make use of a phosphorylated functional group (phosphoramide, phosphate) as a cornerstone of their structure, possess two identical or different lipid chains bonded to the phosphorus functional group whereas the last valence on the phosphorus atom is used to attach a cationic or neutral polar head group. These vectors were successfully used for in vitro and in vivo transfection assays. The supramolecular packing of these amphiphilic compounds can be tuned by ramifying the lipid chains via thiol-ene click reactions; this allows an increased versatility of these cationic lipids. Interestingly, cationic lipids possessing a trimethylarsenium polar head group exhibited outstanding antibacterial properties

Synthesis of ether lipids: natural compounds and analogues

Ether lipids are compounds present in many living organisms including humans that feature an ether bond linkage at the sn-1 position of the glycerol. This class of lipids features singular structural roles and biological functions. Alkyl ether lipids and alkenyl ether lipids (also identified as plasmalogens) correspond to the two sub-classes of naturally occurring ether lipids. In 1979 the discovery of the structure of the platelet-activating factor (PAF) that belongs to the alkyl ether class of lipids increased the interest in these bioactive lipids and further promoted the synthesis of non-natural ether lipids that was initiated in the late 60’s with the development of edelfosine (an anticancer drug). More recently, ohmline, a glyco glycero ether lipid that modulates selectively SK3 ion channels and reduces in vivo the occurrence of bone metastases, and other glyco glycero ether also identified as GAEL (glycosylated antitumor ether lipids) that exhibit promising anticancer properties renew the interest in this class of compounds. Indeed, ether lipid represent a new and promising class of compounds featuring the capacity to modulate selectively the activity of some membrane proteins or, for other compounds, feature antiproliferative properties via an original mechanism of action. The increasing interest in studying ether lipids for fundamental and applied researches invited to review the methodologies developed to prepare ether lipids. In this review we focus on the synthetic method used for the preparation of alkyl ether lipids either naturally occurring ether lipids (e.g., PAF) or synthetic derivatives that were developed to study their biological properties. The synthesis of neutral or charged ether lipids are reported with the aim to assemble in this review the most frequently used methodologies to prepare this specific class of compounds

Involved-field radiotherapy for advanced Hodgkin's lymphoma

BACKGROUND: The use of involved-field radiotherapy after chemotherapy for advanced Hodgkin's lymphoma is controversial. METHODS: We randomly assigned patients with previously untreated stage III or IV Hodgkin's lymphoma who were in complete remission after hybrid chemotherapy with mechlorethamine, vincristine, procarbazine, prednisone, doxorubicin, bleomycin, and vinblastine (MOPP-ABV) to receive either no further treatment or involved-field radiotherapy. Radiotherapy consisted of 24 Gy to all initially involved nodal areas and 16 to 24 Gy to all initially involved extranodal sites. Patients in partial remission were treated with 30 Gy to nodal areas and 18 to 24 Gy to extranodal sites. RESULTS: Of 739 patients, 421 had a complete remission; 161 of these patients were assigned to no further treatment, and 172 to involved-field radiotherapy. The median follow-up was 79 months. The five-year event-free survival rate was 84 percent in the group that did not receive radiotherapy and 79 percent in the group that received involved-field radiotherapy (P=0.35). The five-year overall survival rates were 91 and 85 percent, respectively (P=0.07). Among the 250 patients in partial remission after chemotherapy, the five-year event-free and overall survival rates were 79 and 87 percent, respectively. CONCLUSIONS: Involved-field radiotherapy did not improve the outcome in patients with advanced-stage Hodgkin's lymphoma who had a complete remission after MOPP-ABV chemotherapy. Radiotherapy may benefit patients with a partial response after chemotherap