Discrimination of the V600E Mutation in BRAF by Rolling Circle Amplification and Förster Resonance Energy Transfer

International audienceThe quantification of very low concentrations of circulating tumor DNA (ctDNA) biomarkers from liquid biopsies has become an important requirement for clinical diagnostics and personalized medicine. In particular, the simultaneous detection of wild-type (WT) dsDNA and their cancer-related counterparts presenting single-point mutations with simple, sensitive, specific, and reproducible technologies is paramount for ctDNA assays in clinical practice. Here, we present the development and evaluation of an amplified dsDNA assay based on a combination of isothermal rolling circle amplification (RCA) and time-gated Förster resonance energy transfer (TG-FRET) between a Tb donor and two dye (Cy3.5 and Cy5.5) acceptors. The RCA–FRET assay is free of washing and separation steps and can quantify both WT and mutated (MT) (V600E) dsDNA in the BRAF gene from a single sample in the 75 fM to 4.5 pM (4.5 × 105 to 2.7 × 107 copies) concentration range. This assay includes all steps from denaturation of the dsDNA targets to the final duplexed quantification of WT and MT targets. High assay performance at different dsDNA sequence lengths and high target specificity even in the presence of a large excess of nonspecific cell-free DNA from human plasma samples demonstrated the applicability to clinical samples. The RCA–FRET single-point mutation sensor has the potential to become an important complementary technique for analyzing liquid biopsies in advanced cancer diagnostics

A predictor of unfavourable outcome in neutropenic paediatric patients presenting with fever of unknown origin

Background. No sensitive, specific marker able to discriminate favourable or unfavourable outcome of fever of unknown origin (FUO) at diagnosis has been identified. Procalcitonin, a recently assessed infection marker, may be useful in predicting the outcome of FUO. Methods. We conducted a prospective study examining the following variables: age 0.5-22 years; solid tumour diagnosis; chemotherapy-related grade-4 febrile neutropenia (FN). A complete clinical, bacteriological and biological evaluation was performed at hospital admission (H0). Other investigations depended on clinical status. FUO was considered to be of unfavourable outcome if the fever was persistent or re-appeared at day 3 (or later), or if secondary clinical or microbiological infection occurred. To validate the results of the analysis the data set was randomly split into a training set and a validation set. Results. Out of 172 episodes of FN, 136 episodes were classified as FUO (80%). Seventy-two (53%) were included in this study. PCT values were significantly higher in episodes of unfavourable outcome (P<0.001). None of the other prediction candidates appeared to be significantly linked to the risk of unfavourable outcome. In the validation set, the best PCT cut-off was 0.12 μ/L, which was associated with a sensitivity of 80% and specificity of 64%. Conclusions. PCT-H0 level can predict FUO outcome. A protocol based on PCT-H0 measurement, integrating clinical and bacteriological evaluation, facilitates shorter hospital stays and less antibiotic treatment. Patients with a PCT-H0 value <0.12 μ/L could benefit from an outpatient treatment starting at H48 thus reducing hospitalisation costs and improving quality of life. © 2009 Wiley-Liss, Inc.SCOPUS: ar.jFLWINinfo:eu-repo/semantics/publishe

A Defined Epitope on the Human Choriogonadotropin α-Subunit Interacts with the Second Extracellular Loop of the Transmembrane Domain of the Lutropidchoriogonadotropin Receptor

International audienceThe monoclonal antibody, HT13 recognizes human choriogonadotropin (CG) bound to the extracellular domain of its receptor, but not to the full-length receptor. The HT13 epitope is located in the regions of residues 15-17 and 73-75 of the human CG alpha-subunit. Only one synthetic peptide, lutropin (LH)/CG-receptor-(481-497)-peptide (EL2 peptide), which spans the second putative extracellular loop of the LH/CG-receptor endodomain, prevents recognition of human CG by HT13 mAb. EL2 peptide decreases hormone-induced cAMP production, but not high-affinity binding. An anti-EL2 serum also displays the capacity to inhibit human CG-stimulated cAMP production. These results suggest that the second extracellular loop of the receptor is in contact with the HT13 epitope of human CG alpha-subunit and is involved in signal transduction. A relative orientation of the hormone versus the endodomain is proposed

Irinotecan loaded in eluting beads: preclinical assessment in a rabbit VX2 liver tumor model.

PURPOSE: The purpose of this study was to study the pharmacokinetics of irinotecan injected intravenously, intra-arterially, or loaded onto a delivery platform. MATERIAL AND METHODS: Fifty-four New Zealand White rabbits with VX2 liver tumor, divided in 3 groups of 17 rabbits, each received irinotecan either by intravenous (IV) route, intra-arterial hepatic (IA) route, or loaded on drug-eluting beads (DEBIRI). Animals were killed at 1, 6, and 24 h. Irinotecan and SN-38 concentrations were measured at different time points in serum, tumor, and normal liver. RESULTS: Twelve milligrams of irinotecan were injected IV and IA, whereas 6-16.5 mg were injected loaded onto DEBIRI. Normalized serum irinotecan reached a peak of 333 ng/ml (range 198.8-502.5) for IV, 327.1 ng/ml (range 277.1-495.6) for IA, and 189.7 ng/ml (range 111.1-261.9) for DEBIRI (P &lt; 0.001) delivery. The area-under-the-curve value from 10 to 60 min of serum irinotecan concentration was significantly lower for DEBIRI (P = 0.0009). Tumor irinotecan levels for IV, IA, and DEBIRI (in ng/200 mg of tissue followed by ranges in parentheses) were, respectively, 23.6 (0.3-24.9), 36.5 (7.7-1914.1), and 20.2 (2.9-319) at 1 h; 4.2 (1-27.9), 99.3 (46.6-159.5), and 42.1 (11.3-189) at 6 h; and 2.7 (2.5-6.9), 18.3 (1.5-369.1), and 174.4 (3.4-5147.3) at 24 h (P = 0.02). At 24 h, tumor necrosis was 25% (10-30), 60% (40-91.25), and 95% (76.25-95) for IV, IA, and DEBIRI, respectively (P = 0.03). CONCLUSION: Compared with IV or IA, DEBIRI induces lower early serum levels of irinotecan, a high and prolonged intratumoral level of irinotecan, and a greater rate of tumor necrosis at 24 h. Further evaluation of the clinical benefit of DEBIRI is warranted