Phase II study of gemcitabine combined with oxaliplatin in relapsed or refractory paediatric solid malignancies: An innovative therapy for children with Cancer European Consortium Study.

AIM: To assess objective response rates after 4 cycles of gemcitabine in combination with oxaliplatin in children and adolescents with relapsed or refractory solid tumours. METHODS: This multicentre, non-randomised Phase II study included five strata: neuroblastoma, osteosarcoma, medulloblastoma and other CNS tumours strata with two-stage Simon designs and a miscellaneous, extra-cranial solid tumour stratum with descriptive design. Eligibility criteria included: age 6 months to 21 years; measurable, relapsed or refractory solid malignancy; no more than one previous salvage therapy. Gemcitabine was administered intravenously at 1000 mg/m(2) over 100 min followed by oxaliplatin at 100mg/m(2) over 120 min on Day 1 of a 14-d cycle. Tumour response was assessed every 4 cycles according to WHO criteria. RESULTS: Ninety-three out of 95 patients enrolled in 25 centres received treatment: 12 neuroblastoma; 12 osteosarcoma; 14 medulloblastoma; 13 other CNS tumours and 42 miscellaneous non-CNS solid tumours. Median age was 11.7 years (range, 1.3-20.8 years). Tumour control (CR+PR+SD) at 4 cycles was obtained in 30/93 evaluable patients (32.3%; 95% confidence interval (CI), 22.9-42.7%), including four PR: 1/12 patients with osteosarcoma, 1/12 with medulloblastoma, 1/12 with rhabdomyosarcoma and 1/4 with other sarcoma. Five out of 12 eligible patients with neuroblastoma experienced stable disease. During a total of 481 treatment cycles (median 4, range 1-24 per patient), the most common treatment-related toxicities were haematologic (leukopenia, neutropenia, thrombocytopenia) and neurological (dysesthesia, paresthesia). CONCLUDING STATEMENT: The gemcitabine-oxaliplatin combination administered in a bi-weekly schedule has acceptable safety profile with limited activity in children with relapsed or refractory solid tumours.

Phase I study of topotecan in combination with temozolomide (TOTEM) in relapsed or refractory paediatric solid tumours.

PURPOSE: To evaluate maximum tolerated dose and recommended dose (RD) for phase II studies of topotecan (TPT) combined with temozolomide (TMZ) (TOTEM) in children and adolescents with relapsed or refractory solid malignancies. PATIENTS AND METHODS: Multicentre, phase I study with a standard '3+3' design in five dose increments. Eligible patients: aged 6 months to 21 years, diagnosis of a solid malignancy failed at least 2 previous lines of therapy. TMZ was administered orally, starting at 100 mg/m(2)/d, and TPT intravenously over 30 min, starting at 0.75 mg/m(2)/d over 5 consecutive days every 28 d. A pharmacokinetics analysis was performed on Day 1 and Day 5 of cycle 1. RESULTS: Between February and October 2007, 16 patients were treated. The median age was 8.5 years (range, 3-19 years). Dose-limiting toxicity (grade 4 neutropenia and/or thrombocytopenia lasting more than 7 d) during the first cycle occurred in 2 of 3 patients at level 3 (TMZ 150 mg/m(2)/d and TPT 1.0 mg/m(2)/d) and was always manageable. Confirmed complete and partial responses were observed in 4 patients (25%), three with metastatic neuroblastoma and one with high-grade glioma. Seven patients had a stable disease. Pharmacokinetic data show a wide inter-individual variability. No significant differences were observed between plasma TMZ and TPT concentrations on Day 1 and Day 5 indicating the absence of pharmacokinetic interaction between the drugs. CONCLUSIONS: The RD for the combination is TMZ 150 mg/m(2)/d and TPT 0.75 mg/m(2)/d with dose-limiting haematological toxicity. The observed activity deserves further evaluation in paediatric malignancies.

Synthesis of 3,5-bis(2-indolyl)pyridine and 3-[(2-indolyl)-5-phenyl]pyridine derivatives as CDK inhibitors and cytotoxic agents.

We here report the synthesis and biological evaluation of new 3,5-bis(2-indolyl)pyridine and 3-[(2-indolyl)-5-phenyl]pyridine designed as potential CDK inhibitors. Indole, 5-hydroxyindole, and phenol derivatives were used to generate three substitutions of the pyridine. The resulting skeletons were successively exploited to introduce various dimethylaminoalkyl side chains by Williamson type reactions. The synthesis includes Stille or Suzuki type reactions, which were realized on the 3,5-dibromopyridine. The preparation and the use of stannylindoles in mono or bis cross-coupling reactions were also described and each step was optimized and detailed. Kinase assays were realized and shown that nude compounds 7, 18, and 25 inhibited CDK1 in the 0.3-0.7 micromolar range with a good selectivity over GSK-3. Cytotoxicity against CEM human leukemia cells was evaluated with IC(50) values in the 5-15 micromolar range. Precise structure-activity relationships were delineated. Molecular modeling and docking solutions were proposed to complete the studies and to explain the observed SAR in the CDK assays.

Chiral capillary electrophoretic determination of the enantiomeric purity of homocamptothecin derivatives, promising antitumor topoisomerase I inhibitors, using highly sulfated CDs and fluorescence detection.

EKC methods for the enantiomeric resolution of homocamptothecin derivatives, potent anticancer agents targeting DNA topoisomerase I selected for clinical trials, were developed using highly sulfated beta-CD as chiral selectors at acidic pH. Optimal electrophoretic conditions, with migration times under 15 min, were as follows: for the neutral homocamptothecin analog 1, a BGE of 75 mM phosphate buffer pH 2.5 (H(3)PO(4) + triethanolamine)/ACN - 95/5 v/v, with 7.5% w/v highly S-beta-CD, an applied field of 0.2 kV/cm and a fused capillary temperature control of 30 +/- 0.1 degrees C (typical current approximately 175 microA); for the cationic homocamptothecin 2, a BGE of 25 mM phosphate buffer pH 2.5 (H(3)PO(4) + TEA)/ACN - 90/10 v/v, with 2.5% w/v highly S-beta-CD, an applied field of 0.15 kV/cm and a fused capillary temperature control of 25 +/- 0.1 degrees C (typical current approximately 45 muA), and both are validated. The best results in terms of LOQ were obtained by EC with fluorescence detection: 10 ng/mL and 20 ng/mL for 1 and 2, respectively (LOQ divided by 150 for 1 and 5 for 2 with respect to UV), thus making this method particularly convenient for enantiomeric purity determination of galenic forms. UV detection appears to be an alternative to fluorescence for the analysis of the main component either for the control of galenic forms or for therapeutic adaptation. Moreover, this method exhibits better performances than HPLC.

Synthesis and biological evaluation of novel phenylcarbazoles as potential anticancer agents.

We here report the synthesis and biological evaluation of new phenylcarbazole derivatives designed as potential anticancer agents. Indole and hydroxyindole were used to generate three scaffolds that were successively exploited to introduce various substituents on the maleimide moiety. The synthesis includes a final intramolecular key Heck-type reaction, which was carried out with a triflate derivative or with a bromophenyl derivative. Each step was optimized and the complete chemical strategy is detailed. Several compounds showed a marked cytotoxicity against CEM human leukemia cells with IC(50) values in the 10-100 nM range. Precise structure-activity relationships were delineated. Cell cycle analysis, topoisomerase I inhibition, and interaction with DNA were evaluated, and inhibition of CDK activity was also investigated. Although binding of the drugs to DNA likely contributes to the cytotoxic action, the exact molecular targets of these molecules remain undiscovered. The efficient chemical routes reported here for the design of highly cytotoxic compounds provide novel opportunities to identify antitumor agents in the phenylcarbazole series.

Synthesis of 2,6-diphenylpyrazine derivatives and their DNA binding and cytotoxic properties.

A series of 2,6-diphenylpyrazine derivatives was synthesized from 2,6-dichloropyrazine and 4-methoxyphenylboronic acid using palladium(0) as catalyst in a Suzuki methodology. After deprotection of the hydroxyl, alkylation reactions with different halides afforded compounds 5-8 bearing hydrophilic chains. DNA binding and cytotoxic properties were investigated. Compound 11 bearing imidazoline terminal groups was found to be a potent AT-specific DNA minor groove binder but there was no relationship between DNA interaction and cytotoxicity. However, in all cases the incorporation of the pyrazine ring was found to promote the cytotoxicity of the molecules compared to the corresponding pyridine analogues, previously synthesized.

Oxoazabenzo[de]anthracenes conjugated to amino acids: synthesis and evaluation as DNA-binding antitumor agents.

We report the synthesis of an original series of oxoazabenzo[de]anthracenes conjugated to an amino acid: Ala, Phe, Pro, Lys, or Gly (4a-e, respectively). The compounds, derived from 1,8-dihydroxyanthracene-9,10-dione, were studied for DNA binding and cytotoxicity. Melting temperature, fluorescence quenching, and surface plasmon resonance methods all indicated that the lysine derivative 4d binds to DNA much more strongly that the Pro, Ala, and Gly conjugates whereas the Phe analogue showed the lowest DNA binding capacity. These compounds form intercalation complexes with DNA, as judged from electric linear dichroism and topoisomerase I-based DNA unwinding experiments. Preferential binding of 4d to defined sequences such as 5'-CTAAAGG and 5'-ATGC was evidenced by DNase I footprinting. This Lys conjugate was found to be over 20 times more cytotoxic to CEM human leukemia cells than the other conjugates, with an IC50 in the submicromolar range. A high antiproliferative activity, likely attributable to the enhanced DNA binding capacity, is maintained despite the incapacity of the compound to stabilize topoisomerase-DNA covalent complexes. The cell cycle effects of 4d consisted in an S phase accumulation of cells coupled with a pro-apoptotic action (appearance of hypodiploid sub-G1 cells) which were confirmed by measuring the inhibition of BrdU incorporation into DNA and labeling of phosphatidylserine residues with annexin V-FITC by means of flow cytometry. Altogether, the work provides interesting structure-activity relationships in the oxoazabenzo[de]anthracene-amino acid conjugate series and identifies the lysine derivative 4d as a promising candidate for further in vivo evaluation and drug design.

Synthesis of 2,5- and 3,5-diphenylpyridine derivatives for DNA recognition and cytotoxicity.

A series of 2,5- and 3,5-diphenylpyridine derivatives was synthetised in high yields. A versatile chemical strategy allows the design of diphenylpyridines differently substituted with cationic or neutral side chains. The interaction of the molecules with DNA was investigated by biophysical and biochemical methods and an AT-binder (20) was characterised. A few cytotoxic molecules were identified but their antiproliferative activity does not correlate with DNA binding. Two compounds 18 and 22 showed significant antiproliferative activity and provide a novel route to potential anticancer agents.

Drugs targeting mitochondrial functions to control tumor cell growth.

Mitochondria, the power houses of the cell, are at the cross-road of many cellular pathways. They play a central role in energy metabolism, regulate calcium flux and are implicated in apoptosis. Mitochondrial dysfunctions have been associated with various physiopathological disorders, especially neurodegenerative diseases and cancer. Structurally diverse pharmacological agents have shown direct effects on mitochondria ultra-structures and functions, either at the DNA level or upon targeting proteins located in the inner or outer mitochondrial membranes. The brief review deals with the molecular targets and mechanisms of action of chemically diverse small molecules acting on specific mitochondrial loci, such as the respiratory chain, DNA biogenesis, potassium channels, the Bcl-2 protein and the permeability transition pores (PTP). Drugs, which specifically compromise the structural and functional integrity of mitochondria, may provide novel opportunities to combat cancer cell proliferation, providing that these molecules can be selectively delivered to tumor sites. Different examples reported here show that mitochondrial insult or failure can rapidly lead to inhibition of cell survival and proliferation. Mitochondrial impairment may be a successful anti-cancer strategy.

Synthesis and biological evaluation of novel naphthocarbazoles as potential anticancer agents.

We report the efficient synthesis involving palladium-catalyzed reactions and biological evaluation of new naphthocarbazoles designed as potential anticancer agents. The use of 5- and 6-benzyloxyindoles generated three substitution sites which were successively exploited to introduce several hydrophilic side chains. The cytotoxicity of the newly designed compounds was evaluated on three cell lines. Several compounds showed a marked cytotoxicity with IC(50) values in the sub-micromolar range. This is the case for the 3-hydroxy-naphthopyrrolocarbazoledione 37, bearing a dimethylaminoethyl side chain, which is extremely cytotoxic to L1210 and DU145 cells (IC(50): 36 nM, 108 nM) and induces an accumulation of L1210 cells in the G2+M phases of the cell cycle. Some of the most cytotoxic compounds were tested for inhibition of CDK-5, GSK-3 and topoisomerase I, and their interaction with DNA was also evaluated. Interaction with DNA was detected, suggesting that nucleic acids represent a privileged target for these molecules.

Targeting DNA with novel diphenylcarbazoles.

Double-stranded DNA is a therapeutic target for a variety of anticancer and antimicrobial drugs. Noncovalent interactions of small molecules with DNA usually occur via intercalation of planar compounds between adjacent base pairs or minor-groove recognition by extended crescent-shaped ligands. However, the dynamic and flexibility of the DNA platform provide a variety of conformations that can be targeted by structurally diverse compounds. Here, we propose a novel DNA-binding template for construction of new therapeutic candidates. Four bisphenylcarbazole derivatives, derived from the combined molecular architectures of known antitumor bisphenylbenzimidazoles and anti-infectious dicationic carbazoles, have been designed, and their interaction with DNA has been studied by a combination of biochemical and biophysical methods. The substitutions of the bisphenylcarbazole core with two terminal dimethylaminoalkoxy side chains strongly promote the interaction with DNA, to prevent the heat denaturation of the double helix. The deletion or the replacement of the dimethylamino-terminal groups with hydroxyl groups strongly decreased DNA interaction, and the addition of a third cationic side chain on the carbazole nitrogen reinforced the affinity of the compound for DNA. Although the bi- and tridentate molecules both derive from well-characterized DNA minor-groove binders, the analysis of their binding mode by means of circular and linear dichroism methods suggests that these compounds form intercalation complexes with DNA. Negative-reduced dichroism signals were recorded in the presence of natural DNA and synthetic AT and GC polynucleotides. The intercalation hypothesis was validated by unwinding experiments using topoisomerase I. Prominent gel shifts were observed with the di- and trisubstituted bisphenylcarbazoles but not with the uncharged analogues. These observations, together with the documented stacking properties of such molecules (components for liquid crystals), prompted us to investigate their binding to the human telomeric DNA sequence by means of biosensor surface plasmon resonance. Under conditions favorable to G4 formation, the title compounds showed only a modest interaction with the telomeric quadruplex sequence, comparable to that measured with a double-stranded oligonucleotide. Their sequence preference was explored by DNase I footprinting experiments from which we identified a composite set of binding sequences comprising short AT stretches and a few other mixed AT/GC blocks with no special AT character. The variety of the binding sequences possibly reflects the coexistence of distinct positioning of the chromophore in the intercalation sites. The bisphenylcarbazole unit represents an original pharmacophore for DNA recognition. Its branched structure, with two or three arms suitable to introduce a structural diversity, provides an interesting scaffold to built molecules susceptible to discriminate between the different conformations of nucleic acids.

Analogues of antifungal tjipanazoles from rebeccamycin.

Analogues of antifungal tjipanazoles were obtained by semi-synthesis from rebeccamycin, an antitumor antibiotic isolated from cultures of Saccharothrix aerocolonigenes. The antiproliferative activities of the new compounds were evaluated in vitro against nine tumor cell lines. The effect on the cell cycle of murine leukemia L1210 cells was examined and the antimicrobial activities against two Gram positive bacteria, a Gram negative bacterium and a yeast were determined. The inhibitory properties toward four kinases and toward topoisomerase I were evaluated. The most cytotoxic compound in the series was a dinitro derivative characterized as a potent topoisomerase I inhibitor.

Semi-synthesis, topoisomerase I and kinases inhibitory properties, and antiproliferative activities of new rebeccamycin derivatives.

In the course of structure-activity relationship studies, new rebeccamycin derivatives substituted in 3,9-positions on the indolocarbazole framework, and a 2',3'-anhydro derivative were prepared by semi-synthesis from rebeccamycin. The antiproliferative activities against nine tumor cell lines were determined and the effect on the cell cycle of murine leukemia L1210 cells was examined. Their DNA binding properties and inhibitory properties toward topoisomerase I and three kinases PKCzeta, CDK1/cyclin B, CDK5/p25 and a phosphatase cdc25A were evaluated. The 3,9-dihydroxy derivative is the most efficient compound of this series toward CDK1/cyclin B and CDK5/p25. It is also characterized as a DNA binding topoisomerase I poison. Its broad spectrum of molecular activities likely accounts for its cytotoxic potential. This compound which displays a tumor cell line-selectivity may represent a new lead for subsequent drug design in this series of glycosylated indolocarbazoles.

Potential roles of antisense oligonucleotides in cancer therapy. The example of Bcl-2 antisense oligonucleotides.

Antisense oligonucleotides have been widely used to specifically and selectively downregulate gene expression at the messenger RNA level. Even though oligonucleotides are commonly used in laboratories and clinical trials, they can induce non-specific effects that can lead to misinterpretation of experimentally-derived results. This review summarizes precautions one should take when using oligonucleotides. In addition, the role of one oligonucleotide, G3139, which is targeted to the coding region of bcl-2 messenger RNA, in inhibiting tumor progression in vitro and in clinical trials, is described.

RNA hairpin invasion and ribosome elongation arrest by mixed base PNA oligomer.

Recently, we have shown that peptide nucleic acid (PNA) tridecamers targeted to the codon 74, 128 and 149 regions of Ha-ras mRNA arrested translation elongation in vitro. Our data demonstrated for the first time that PNAs with mixed base sequence targeted to the coding region of a messenger RNA could arrest the translation machinery and polypeptide chain elongation. The peculiarity of the complexes formed with PNA tridecamers and Ha-ras mRNA rests upon the stability of PNA-mRNA hybrids, which are not dissociated by cellular proteins or multiple denaturing conditions. In the present study, we show that shorter PNAs such as a dodecamer or an undecamer targeted to the codon 74 region arrest translation elongation in vitro. The 13, 12, and 11-mer PNAs contain eight and the 10-mer PNA seven contiguous pyrimidine residues. Upon binding with parallel Hoogsteen base-pairing to the PNA-RNA duplex, six of the cytosine bases and one thymine base of a second PNA can form C.G*C(+) and T.A*T triplets. Melting experiments show two well-resolved transitions corresponding to the dissociation of the third strand from the core duplex and to melting of duplex at higher temperature. The enzymatic structure mapping of a target 27-mer RNA revealed a hairpin structure that is disrupted upon binding of tri-, dodeca-, undeca- and decamer PNAs. We show that the non-bonded nucleobase overhangs on the RNA stabilize the PNA-RNA hybrids and probably assist the PNA in overcoming the stable secondary structure of the RNA target. The great stability of PNA-RNA duplex and triplex structures allowed us to identify both 1:1 and 2:1 PNA-RNA complexes using matrix-assisted laser desorption/ionization time-of -flight mass spectrometry. Therefore, it is possible to successfully target mixed sequences in structured regions of messenger RNA with short PNA oligonucleotides that form duplex and triplex structures that can arrest elongating ribosomes.