Modern Strategies for Carbon Isotope Exchange.

In contrast to stable and natural abundant carbon-12, the synthesis of organic molecules with carbon (radio)isotopes must be conceived and optimized in order to navigate through the hurdles of radiochemical requirements, such as high costs of the starting materials, harsh conditions and radioactive waste generation. In addition, it must initiate from the small cohort of available C-labeled building blocks. For long time, multi-step approaches have represented the sole available patterns. On the other side, the development of chemical reactions based on the reversible cleavage of C-C bonds might offer new opportunities and reshape retrosynthetic analysis in radiosynthesis. This review aims to provide a short survey on the recently emerged carbon isotope exchange technologies that provide effective opportunity for late-stage labeling. At present, such strategies have relied on the use of primary and easily accessible radiolabeled C1-building blocks, such as carbon dioxide, carbon monoxide and cyanides, while the activation principles have been based on thermal, photocatalytic, metal-catalyzed and biocatalytic processes.

Identification of predictive factors of response to the BH3-mimetic molecule ABT-737: an ex vivo experiment in human serous ovarian carcinoma.

Ovarian cancers are addicted to Bcl-xL and Mcl-1, antiapoptotic members of the Bcl-2 family. Bcl-xL can be inhibited by the BH3-mimetic ABT-737. In vitro, ABT-737 can induce apoptosis of cancer cells, and its activity is potentiated by Mcl-1 inactivation. Herein, we assessed the sensitivity of human ovarian tumor nodes to ABT-737 when combined with carboplatin, which can indirectly inhibit Mcl-1. Fresh samples from 25 patients with high-grade serous ovarian cancer (HGSOC) who were chemo-naïve and had undergone surgery were prospectively exposed ex vivo to ABT-737 ± carboplatin. The treatment effect was studied on sliced tumor nodes by assessment of cleaved-caspase 3 immunostaining. We also studied the association between baseline Bcl-2 family protein expression (via immunohistochemistry) and the response of nodes to treatment. ABT-737 induced apoptosis as a single agent but its efficacy was not improved by the addition of carboplatin. Bim was frequently expressed (20/25) and its absence or low expression was associated with the absence of response to ABT-737, p value = 0.019 by Fisher's test and sensitivity = 93%, (95% confidence interval, 66-100). Moreover, we observed that in tumors in which Bim was expressed, a low expression of phospho-Erk1/2 or Mcl-1 improved the proportion of responses. This pilot study showed that ABT-737 has promise as monotherapy for HGSOC in a specific subgroup of tumors. Bim, Mcl-1, and phospho-Erk1/2 appeared to be relevant biomarkers that could be used for the selection of patients in the design of clinical trials using Navitoclax (an orally available compound related to ABT-737).

Stromal compartment as a survival prognostic factor in advanced ovarian carcinoma.

OBJECTIVE: We investigated the prognostic significance of stromal compartment on the overall survival of patients with advanced epithelial ovarian cancer. METHODS: We evaluated retrospectively the stroma proportion of the tumor surgical specimens of 194 patients with stages III and IV disease, using histochemical staining and fully automatic virtual slide processing. The prognostic significance of stroma proportion and clinical parameters were evaluated using log-rank test and Cox regression. RESULTS: Stroma proportion was found to be an independent prognostic factor by both univariate (P = 0.016) and multivariate analyses (hazards ratio = 1.45, P = 0.011). CONCLUSION: The present data indicate that a high stroma proportion is related to a poor prognosis of stage III and IV ovarian carcinomas.

Prognostic significance of tumour vascularisation on survival of patients with advanced ovarian carcinoma.

OBJECTIVE: The prognostic significance of microvessel density in ovarian cancer is still a matter of debate. Classically, the degree of vascularisation is assessed in areas of high vascular density (hot spots), considered as regions of increased probability of metastasis. Since ovarian tumours have a particular progression and dissemination behaviour, vascularisation outside hot spots may also contribute to their evolution. METHODS: In the present study, the degree of tumour vascularisation was estimated both in whole histogical sections and in hot spots, in 235 patients with ovarian carcinoma, using fully automatic image analysis methods. Six parameters were estimated: mean microvessel density (MVD) and mean microvessel surface fraction (MSP) on the whole section, mean and maximum values of MVD and MSP inside hot spots (MVDHS1, MSPHS1 and MVDHS2, MSPHS2). Relationships between vascular parameters and clinicopathologic features were analysed. RESULTS: In stage III-IV patients multivariate analysis showed that stage IV disease (hazards ratio (HR)=1.72, p=0.001), post-surgical residual disease 1cm (HR=2.86, p<0.001), upper MVD tercile (HR=1.45, p<0.022) and medial MVDHS1 tercile (HR=1.36, p=0.060) retained an independent prognostic value upon overall survival. CONCLUSION: Our results suggest that quantification of blood vessels, both on the whole histological section and in hot spots might be helpful in evaluating prognosis in advanced ovarian carcinomas.

Early evaluation of the effects of chemotherapy with longitudinal FDG small-animal PET in human testicular cancer xenografts: early flare response does not reflect refractory disease.

AIM: We aimed to evaluate the usefulness of FDG PET in the early prediction of the effects of chemotherapy on human testicular cancer xenografts. MATERIAL AND METHODS: Nude rats bearing subcutaneous human embryonal carcinoma xenografts received either cisplatin (5 mg/kg) or saline serum. Small-animal PET studies were performed on days 0, 2, 4 and 7 and compared to immunochemistry studies, flow cytometry studies and hexokinase assays. RESULTS: Cisplatin treatment resulted in biphasic FDG uptake evolution: a peak was observed on day 2, followed by a marked decrease on day 7 despite an insignificant change in tumour volume. Similarly, a peak in cyclin A immunostaining was observed on days 2 and 4), followed by a significant decrease on day 7. Flow cytometry showed that the cyclin A peak was not related to increased cell proliferation but was due to a transient S and G(2)/M cell cycle arrest. A marked increase in cell apoptosis was observed from day 2 to day 7. GLUT-1 showed a significant decrease on day 7. Macrophagic infiltrate remained stable except for an increase observed on day 7. In control tumours, continuous growth was observed, all immunostaining markers remaining stable over time. Hexokinase activity was significantly lower on day 7 in treated tumours than in controls. CONCLUSION: FDG PET may be useful in the early evaluation of treatment in patients with testicular cancer. In our model, a very early increased [(18)F]-FDG uptake was related to a transient cell cycle arrest and early stage apoptosis but did not reveal refractory disease.

Usefulness of automatic quantification of immunochemical staining on whole tumor sections for correlation with oncological small animal PET studies: an example with cell proliferation, glucose transporter 1 and FDG.

AIM: To highlight the use of automatic quantification of immunochemical staining on digitized images of whole tumor sections in preclinical positron emission tomography (PET) studies. MATERIALS AND METHODS: Xenografted human testicular tumors (36) were imaged with 2-deoxy-2[F-18]fluoro-D: -glucose (FDG) small animal PET (SA-PET). Tumor cell proliferation and glucose transportation were assessed with cyclin A and Glut-1 immunostaining. Tumor slides were digitized and processed with PixCyt software enabling whole slide quantification, then compared with junior and senior pathologist manual scoring. Manual and automatic quantification results were correlated to FDG uptake. RESULTS: For cyclin A, inter- and intra-observer agreement for manual scoring was 0.52 and 0.72 and concordance between senior pathologist and automatic quantification was 0.84. Correlations between Tumor/Background ratio and tumor cell proliferation assessed by automatic quantification, junior and senior pathologists were 0.75, 0.55, and 0.61, respectively. Correlation between Tumor/Background ratio and Glut-1 assessed by automatic quantification was 0.74. CONCLUSION: Automatic quantification of immunostaining is a valuable tool to overcome inter- and intra-observer variability for correlation of cell proliferation or other markers with tumor tracer uptake.

Improvement of semi-quantitative small-animal PET data with recovery coefficients: a phantom and rat study.

AIM: To evaluate the accuracy of semi-quantitative small-animal PET data, uncorrected for attenuation, and then of the same semi-quantitative data corrected by means of recovery coefficients (RCs) based on phantom studies. MATERIALS AND METHODS: A phantom containing six fillable spheres (diameter range: 4.4-14 mm) was filled with an 18F-FDG solution (spheres/background activity=10.1, 5.1 and 2.5). RCs, defined as measured activity/expected activity, were calculated. Nude rats harbouring tumours (n=50) were imaged after injection of 18F-FDG and sacrificed. The standardized uptake value (SUV) in tumours was determined with small-animal PET and compared to ex-vivo counting (ex-vivo SUV). Small-animal PET SUVs were corrected with RCs based on the greatest tumour diameter. Tumour proliferation was assessed with cyclin A immunostaining and correlated to the SUV. RESULTS: RCs ranged from 0.33 for the smallest sphere to 0.72 for the largest. A sigmoidal correlation was found between RCs and sphere diameters (r(2)=0.99). Small-animal PET SUVs were well correlated with ex-vivo SUVs (y=0.48x-0.2; r(2)=0.71) and the use of RCs based on the greatest tumour diameter significantly improved regression (y=0.84x-0.81; r(2)=0.77), except for tumours with important necrosis. Similar results were obtained without sacrificing animals, by using PET images to estimate tumour dimensions. RC-based corrections improved correlation between small-animal PET SUVs and tumour proliferation (uncorrected data: Rho=0.79; corrected data: Rho=0.83). CONCLUSION: Recovery correction significantly improves both accuracy of small-animal PET semi-quantitative data in rat studies and their correlation with tumour proliferation, except for largely necrotic tumours.