Search

International audience; For all fabrication processes of the photovoltaic (PV) industry based on silicon, grain boundaries, dislocations, and impurity contamination control during solidification remains a major challenge to improve the electrical properties. In particular, carbon (C) is a major deleterious impurity for solar cells. The combination of X-ray radiography and Bragg diffraction imaging (topography) achieved in situ during silicon solidification allowed us to characterise the dynamics of the growth mechanisms involved in the formation of the grain structure and of defects, related to the presence of C. Ex situ techniques were used to characterise the grain structure and for a more precise analysis of the defects and their associated distortion fields. In the presence of C, it is shown that the resulting grain structure is constituted by a higher proportion of high-order and incoherent twin boundaries compared with the case of pure samples. Crystal distortion is characterised at the grain scale level and at a lower scale, both in situ and after cooling-down. The highest distortion at the grain scale corresponds to the position of the high order twin boundaries and is accentuated during cooling-down following solidification. Locally distorted regions and sub-grains are distributed all over the samples. They are observed in situ during the solidification from various seeds containing C (mono-crystals, industrial ribbons and multi-crystalline samples) and are retrieved after solidification. A model implying the presence of SiC precipitates at the solid-liquid interface is proposed to explain the formation during solidification of these sub-grains and of the associated local distortion.

Supplementary Data from Next-Generation Sequencing of Minimal Residual Disease for Predicting Relapse after Tisagenlecleucel in Children and Young Adults with Acute Lymphoblastic Leukemia

We assessed minimal residual disease (MRD) detection and B-cell aplasia after tisagenlecleucel therapy for acute lymphoblastic leukemia (ALL) to define biomarkers predictive of relapse (N = 143). Next-generation sequencing (NGS) MRD detection >0 in bone marrow (BM) was highly associated with relapse. B-cell recovery [signifying loss of functional chimeric antigen receptor (CAR) T cells] within the first year of treatment was associated with a hazard ratio (HR) for relapse of 4.5 [95% confidence interval (CI), 2.03–9.97; P < 0.001]. Multivariate analysis at day 28 showed independent associations of BMNGS-MRD >0 (HR = 4.87; 95% CI, 2.18–10.8; P < 0.001) and B-cell recovery (HR = 3.33; 95% CI, 1.44–7.69; P = 0.005) with relapse. By 3 months, the BMNGS-MRD HR increased to 12 (95% CI, 2.87–50; P < 0.001), whereas B-cell recovery was not independently predictive (HR = 1.27; 95% CI, 0.33–4.79; P = 0.7). Relapses occurring with persistence of B-cell aplasia were largely CD19− (23/25: 88%). Detectable BMNGS-MRD reliably predicts risk with sufficient time to consider approaches to relapse prevention such as hematopoietic cell transplantation (HCT) or second CAR-T cell infusion.Significance:Detectable disease by BMNGS-MRD with or without B-cell aplasia is highly predictive of relapse after tisagenlecleucel therapy for ALL. Clonotypic rearrangements used to follow NGS-MRD did not change after loss of CD19 or lineage switch. High-risk patients identified by these biomarkers may benefit from HCT or investigational cell therapies.See related commentary by Ghorashian and Bartram, p. 2.This article is highlighted in the In This Issue feature, p. 1

Differentially Expressed Proteins Deleted versus non-deleted clones

Supp Fig. S1-6, Supp Tables S1-S3, Supp Methods and References

Deletion of chromosome 6q is a well-recognized abnormality found in poor-prognosis T-cell acute lymphoblastic leukemia (T-ALL). Using integrated genomic approaches, we identified two candidate haploinsufficient genes contiguous at 6q14, SYNCRIP (encoding hnRNP-Q) and SNHG5 (that hosts snoRNAs), both involved in regulating RNA maturation and translation. Combined silencing of both genes, but not of either gene alone, accelerated leukemogeneis in a Tal1/Lmo1/Notch1-driven mouse model, demonstrating the tumor-suppressive nature of the two-gene region. Proteomic and translational profiling of cells in which we engineered a short 6q deletion by CRISPR/Cas9 genome editing indicated decreased ribosome and mitochondrial activities, suggesting that the resulting metabolic changes may regulate tumor progression. Indeed, xenograft experiments showed an increased leukemia-initiating cell activity of primary human leukemic cells upon coextinction of SYNCRIP and SNHG5. Our findings not only elucidate the nature of 6q deletion but also highlight the role of ribosomes and mitochondria in T-ALL tumor progression.Significance:The oncogenic role of 6q deletion in T-ALL has remained elusive since this chromosomal abnormality was first identified more than 40 years ago. We combined genomic analysis and functional models to show that the codeletion of two contiguous genes at 6q14 enhances malignancy through deregulation of a ribosome–mitochondria axis, suggesting the potential for therapeutic intervention.This article is highlighted in the In This Issue feature, p. 1494

Purpose: Tumor cells residing in tumor hypoxic zones are a major cause of drug resistance and tumor relapse. In this study, we investigated the efficacy of evofosfamide, a hypoxia-activated prodrug, and its combination with topotecan in neuroblastoma and rhabdomyosarcoma preclinical models.Experimental Design: Neuroblastoma and rhabdomyosarcoma cells were tested in vitro to assess the effect of evofosfamide on cell proliferation, both as a single agent and in combination with topotecan. In vivo antitumor activity was evaluated in different xenograft models. Animal survival was studied with the neuroblastoma metastatic tumor model.Results: All tested cell lines showed response to evofosfamide under normoxic conditions, but when exposed to hypoxia overnight, a 2- to 65-fold decrease of IC50 was observed. Adding topotecan to the evofosfamide treatment significantly increased cytotoxicity in vitro. In neuroblastoma xenograft models, single-agent evofosfamide treatment delayed tumor growth. Complete tumor regression was observed in the combined topotecan/evofosfamide treatment group after 2-week treatment. Combined treatment also improved survival in a neuroblastoma metastatic model, compared to single-agent treatments. In rhabdomyosarcoma xenograft models, combined treatment was more effective than single agents. We also showed that evofosfamide mostly targeted tumor cells within hypoxic regions while topotecan was more effective to tumor cells in normoxic regions. Combined treatment induced tumor cell apoptosis in both normoxic and hypoxic regions.Conclusions: Evofosfamide shows antitumor effects in neuroblastoma and rhabdomyosarcoma xenografts. Compared with single-agent, evofosfamide/topotecan, combined therapy improves tumor response, delays tumor relapse, and enhances animal survival in preclinical tumor models. Clin Cancer Res; 22(11); 2697–708. ©2015 AACR.

PDF file - 73K

Limited anti-tumor effects of ifosfamide in the CHLA-20 xenograft model. A total of 1 Ã- 106 CHLA-20 cells were implanted subcutaneously into SCID/SCID mice. Once tumors were palpable (about 0.25cm3), mice were randomized into vehicle control (n=6) or ifosfamide treatment group (n = 6 for each group). Ifosfamide was administered intraperitoneally at 50 mg/kg five times a week. After 2 weeks, there was slightly delay of tumor growth with ifosfamide treatment, but the difference between control tumors and ifosfamide group was not statistically significant (p>0.05).

Continued 3-day hypoxia does not increase cytotoxicity of evofosfamide compared to overnight hypoxia. A panel of two NBL cell lines (CHLA-20 and SK-N-BE(2)) and two rhabdomyosarcoma cell line (RH4 and RD) were selected to assess the effects of evofosfamide on cell proliferation in vitro. Cell viability was measured by Alamar Blue assays after exposing tumor cells to increasing concentrations of evofosfamide in vitro for 72 hours under normoxia, 1% O2 for 2 hours, 1% O2 overnight, or 1% O2 for three days. Dose-response curves were fit to the data by GraphPad Prism software.

CCR Translation for This Article from A Phase I Trial and Pharmacokinetic Study of Aflibercept (VEGF Trap) in Children with Refractory Solid Tumors: A Children's Oncology Group Phase I Consortium Report

Topotecan enhanced intracellular ROS in rhabdomyosarcoma cells under hypoxia. Tumor cells were exposed different concentrations of evofosfamide overnight with or without the presence of topotecan (20nM). DCFDA assay was performed as described above. The results are expressed as the percentage of DCF fluorescence intensity with respect to controls cells under normoxia. Data are means {plus minus} SEM of three independent experiments. *P

Increased ROS in neuroblastoma and rhabdomyosarcoma cells under hypoxia. The generation of intracellular oxidative activities was evaluated by measuring intracellular peroxide-dependent oxidation of 2′,7′-dichlorodihydrofluorescein diacetate (DCFDA, Sigma D6883) to form the fluorescent compound, 2′,7′-dichlorofluorescein (DCF) (50). Tumor cells were cultured in 96-well culture plates. After culturing overnight under normoxic or hypoxic (1%O2) conditions, the cells were incubated with 20μM of DCFDA at 37{degree sign}C for 30min. The culture medium was then removed, and the cells were washed twice with Hank's buffered salt solution. The fluorescence intensity of the cells in each well was determined using a Spectromax plate reader with excitation at 495nm and emission at 529nm. Thereafter cell viability was determined by AlamarBlue assay and DCF fluorescence was normalized to the viability. Results are expressed as a percentage of fluorescence intensity with respect to the cells under normoxic conditions. Error bars indicate SEM from three independent experiments. *P

PDF file - 229K, Supplementary Figure 1. Expression of SPARC and PTEN in neuroblastoma cell lines. SPARC and PTEN expression were assessed in a panel of eight neuroblastoma cell lines by Western Blot. For Western blot analysis, 50 microg protein was resolved over 10% polyacrylamide gels and transferred to a nitrocellulose membrane. The blot was blocked in blocking buffer (5% non-fat dry milk/1� Tween 20 in TBS) for 1 h at room temperature, incubated with polyclonal primary antibodies against SPARC (Cell Signaling Technology) and PTEN (Cell Signaling Technology) overnight at 4 {degree}C. The blot was then incubated with appropriate horseradish peroxidase conjugated secondary antibody and detected by enhanced chemiluminescence and autoradiography using X-ray film. beta-actin was detected on the same membrane and used as a loading control

Purpose: To investigate the antitumor effect of nab-paclitaxel, an albumin-stabilized nanoparticle formulation of paclitaxel, on pediatric solid tumor models.Experimental Design: A panel of three rhabdomyosarcoma, one osteosarcoma and seven neuroblastoma cell lines were exposed to increasing concentrations of nab-paclitaxel in vitro. Cell viability was evaluated using the Alamar Blue Assay. Antitumor effect was further assessed in vivo in NOD/SCID xenograft and metastatic neuroblastoma mouse models. Tumor sections were analyzed by immunohistochemistry for cleaved caspase-3 and phospho-histone H3. Plasma and intratumoral paclitaxel concentrations were measured by liquid chromatography–mass spectrometry. Ratio of intratumoral and plasma concentration was compared between nab-paclitaxel and paclitaxel treatment groups.Results: Nab-paclitaxel displayed significant cytotoxicity against most pediatric solid tumor cell lines in vitro in a dose-dependent manner. In vivo, nab-paclitaxel showed antitumor activity in both rhabdomyosarcoma (RH4 and RD) and neuroblastoma [SK-N-BE(2) and CHLA-20] xenograft models. In the SK-N-BE(2) metastatic model, nab-paclitaxel treatment significantly extended animal survival compared with control (P < 0.01). Nab-paclitaxel treatment induced tumor cell-cycle arrest and apoptosis in vivo. In the RH4 model, increased local relapse-free intervals were observed with nab-paclitaxel treatment (37.7 ± 3.2 days) comparing with paclitaxel (13.6 ± 2.07 days). Local relapsed tumors following paclitaxel treatment proved to be paclitaxel-resistant and remained responsive to nab-paclitaxel. Mechanistically, a higher tumor/plasma paclitaxel drug ratio in favor of nab-paclitaxel was observed.Conclusions: Nab-paclitaxel showed significant antitumor activity against all pediatric solid tumors associated with an enhanced drug intratumor delivery. Furthermore, testing of nab-paclitaxel in pediatric solid-tumor patient population is under development. Clin Cancer Res; 19(21); 5972–83. ©2013 AACR.