Systemic delivery of sticky siRNAs targeting the cell cycle for lung tumor metastasis inhibition.

RNA interference allows the design of new inhibitors that target deregulated pathways in cancer. However systemic delivery of siRNA for the treatment of solid tumors still remains an issue. In our study, in order to suppress the progression of lung cancer metastasis in mice, we developed sticky siRNA (ssiRNA) to inhibit survivin and cyclin B1, two candidates involved in cell survival and proliferation. We exploited the linear polyethylenimine (PEI) as potent non-viral carrier to efficiently deliver our inhibitors. As a proof of concept, we have chosen a very aggressive mammary adenocarcinoma model (TSA-Luc cells), which forms lung metastases upon systemic cell injection. We confirmed in vitro, that the ssiRNAs delivered with PEI are not only able to inhibit our target genes at the mRNA and protein levels, but are also able to block the cell cycle and cell proliferation through a mechanism of RNA interference. More importantly, we showed in vivo by luciferase dosage, bioimaging and tissue section, an inhibition of lung tumor metastases after systemic delivery of cyclin B1 and survivin ssiRNA complexed with PEI. Alternating treatment with cisplatin and ssiRNA/PEI showed an additive effect between the two anticancer drugs on lung tumor inhibition leading to a significant increase in animal survival. Moreover a promising window between activity (IC50) and toxicity (LD50), essential for therapeutic application, was observed. Our data show that systemic delivery of ssiRNA/PEI complexes targeting the cell cycle is a valuable strategy for the treatment of lung tumor metastasis and that it can be combined with chemotherapy.

A randomized phase II non-comparative study of pemetrexed­carboplatin and gemcitabine­vinorelbine in anthracycline- and taxane-pretreated advanced breast cancer patients.

Pemetrexed-carboplatin and gemcitabine­vinorelbine combination therapies were efficacious in phase II and phase III studies as first-line breast cancer treatment. Thus, Arm A and Arm B combinations were investigated in patients pretreated with anthracycline and taxanes. Women with advanced breast cancer, with ≥1 measurable lesion per RECIST, were stratified by line of treatment (1st, 2nd), visceral disease (yes/no), ECOG PS (0-1 vs. 2) and randomized 1:1 to Arm A (pemetrexed 600 mg/m², D1 i.v. q21; carboplatin, AUC 5, D1 i.v. q21) or Arm B (gemcitabine 1,200 mg/m² D1, D8 i.v. q21; vinorelbine 30 mg/m² D1, D8 i.v. q21). Treatment continued until progression. The primary endpoint was objective response rate (RR). Secondary endpoints were duration of response (DoR), time-to-response (TTR), time-to-progressive disease (TTPD), time-to-treatment failure (TTTF) and safety. A two-stage design was employed independently for each arm. Of 135 randomized patients, 125 (Arm A, n=64; Arm B, n=61) qualified for tumor-response analysis. The mean (standard deviation) number of cycles administered was 6.3 (4.13) in Arm A and 6.2 (4.39) in Arm B. Efficacy in Arm A and Arm B were: RR (95% CI), 26.6 (16.3-39.1) and 29.5 (18.5-42.6); time-to-events (months), DoR 7.7 and 7.5; TTPD, 5.1 and 5.6; TTR, 1.8 and 1.8; TTTF, 4.8 and 5.1; respectively. Most common grade 3/4 adverse events possibly related to study-drug were neutropenia, thrombocytopenia, anemia and leucopenia in Arm A and neutropenia, leucopenia and fatigue in Arm B. In this study, both combinations showed moderate activity as predefined RR was not reached and were well tolerated.

Conjugating phosphospermines to siRNAs for improved stability in serum, intracellular delivery and RNAi-mediated gene silencing.

siRNAs are usually formulated with cationic polymers or lipids to form supramolecular particles capable of binding and crossing the negatively charged cell membrane. However, particles hardly diffuse through tissues when administered in vivo. We therefore are developing cationic siRNAs, composed of an antisense sequence annealed to an oligophosphospermine-conjugated sense strand. Cationic siRNAs have been previously shown to display gene silencing activity in human cell line (Nothisen et al. J. Am. Chem. Soc.2009). We have improved the synthesis, purification and characterization of oligospermine-oligoribonucleotide conjugates which provide cationic siRNAs with enhanced biological activity. We show data supporting their carrier-free intracellular delivery in a molecular, soluble state. Additional results on the relationship between global charge, uptake and silencing activity confirm the requirement for an overall positive charge of the conjugated siRNA in order to enter cells. Importantly, conjugated siRNAs made of natural phosphodiester nucleotides are protected from nuclease degradation by the oligophosphospermine moiety, operate through the RNAi mechanism and mediate specific gene silencing at submicromolar concentration in the presence of serum.

Zip nucleic acids are potent hydrolysis probes for quantitative PCR.

Zip nucleic acids (ZNAs) are oligonucleotides conjugated with cationic spermine units that increase affinity for their target. ZNAs were recently shown to enable specific and sensitive reactions when used as primers for polymerase chain reaction (PCR) and reverse-transcription. Here, we report their use as quantitative PCR hydrolysis probes. Ultraviolet duplex melting data demonstrate that attachment of cationic residues to the 3' end of an oligonucleotide does not alter its ability to discriminate nucleotides nor the destabilization pattern relative to mismatch location in the oligonucleotide sequence. The stability increase provided by the cationic charges allows the use of short dual-labeled probes that significantly improve single-nucleotide polymorphism genotyping. Longer ZNA probes were shown to display reduced background fluorescence, therefore, generating greater sensitivity and signal level as compared to standard probes. ZNA probes thus provide broad flexibility in assay design and also represent an effective alternative to minor groove binder- and locked nucleic-acid-containing probes.

Zip Nucleic Acids: new high affinity oligonucleotides as potent primers for PCR and reverse transcription.

Most nucleic acid-based technologies rely upon sequence recognition between an oligonucleotide and its nucleic acid target. With the aim of improving hybridization by decreasing electrostatic repulsions between the negatively charged strands, novel modified oligonucleotides named Zip nucleic acids (ZNAs) were recently developed. ZNAs are oligonucleotide-oligocation conjugates whose global charge is modulated by the number of cationic spermine moieties grafted on the oligonucleotide. It was demonstrated that the melting temperature of a hybridized ZNA is easily predictable and increases linearly with the length of the oligocation. Furthermore, ZNAs retain the ability to discriminate between a perfect match and a single base-pair-mismatched complementary sequence. Using quantitative PCR, we show here that ZNAs are specific and efficient primers displaying an outstanding affinity toward their genomic target. ZNAs are particularly efficient at low magnesium concentration, low primer concentrations and high annealing temperatures, allowing to improve the amplification in AT-rich sequences and potentially multiplex PCR applications. In reverse transcription experiments, ZNA gene-specific primers improve the yield of cDNA synthesis, thus increasing the accuracy of detection, especially for genes expressed at low levels. Our data suggest that ZNAs exhibit faster binding kinetics than standard and locked nucleic acid-containing primers, which could explain why their target recognition is better for rare targets.

Laser-evoked potentials correlate with clinical evolution in a case of spontaneous and recurrent complex regional pain syndrome type I.

We describe a case of spontaneous complex regional pain syndrome developing first in the left arm and 2 years later in the right foot of a 14-year-old girl. Physical examination showed abnormalities in tactile and thermal sensitivity. Laser-evoked potentials (LEPs) after stimulation of the affected right foot were absent in the acute phase and then progressively recovered over a period of 5 months, in correlation with clinical changes. To our knowledge, no systematic analysis of LEPs in complex regional pain syndrome has been published. We suggest that the observed electrophysiologic alterations could result from a temporary dysfunction of attentional systems, which are assumed to contribute greatly to the LEPs vertex complex. Further studies are needed to test this hypothesis.