Cancer cells generally generate higher amounts of reactive oxygen species than normal cells. On the basis of this difference, prodrugs have been developed (e.g., hydroxyferrocifen), which remain inactive in normal cells, but become activated in cancer cells. In this work we describe novel aminoferrocene-based prodrugs, which, in contrast to hydroxyferrocifen, after activation form not only quinone methides (QMs), but also catalysts (iron or ferrocenium ions). The released products act in a concerted fashion. In particular, QMs alkylate glutathione, thereby inhibiting the antioxidative system of the cell, whereas the iron species induce catalytic generation of hydroxyl radicals. Since the catalysts are formed as products of the activation reaction, it proceeds autocatalytically. The most potent prodrug described here is toxic toward cancer cells (human promyelocytic leukemia (HL-60), IC(50) = 9 μM, and human glioblastoma-astrocytoma (U373), IC(50) = 25 μM), but not toxic (up to 100 μM) toward representative nonmalignant cells (fibroblasts).

Despite the clinical application of adeno-associated virus (AAV) gene therapy, the titration of viral stocks has not yet been standardized. This complicates the comparison of viral stocks between laboratories. Functional titering of AAV is time-consuming, requires the manipulation of hazardous material, and often has a high degree of variability. We established an optimized real-time quantitative polymerase chain reaction (RQ-PCR) titration assay to determine viral titers and compared it with a functional green fluorescent protein (GFP)-based titration method. With a combination of improved lysis procedures and RQ-PCR protocols we could decrease the intraexperimental coefficient of variation (CV) from 0.24 +/- 0.03 to 0.042 +/- 0.004 and the interexperimental CV from 0.34 +/- 0.06 to 0.093 +/- 0.028 following functional and RQPCR-based titration, respectively. This low variability conforms to even the strictest quality standards required, for example, in clinical laboratories. The highly standardized titration by RQPCR described here will be especially advantageous for groups working on AAV-based gene therapy in a good manufacturing practice setting.

Radiotherapy is a crucial component of cancer care, employed in the treatment of over 50% of cancer patients. Patients undergoing image-guided radiotherapy or brachytherapy routinely have inert radiotherapy (RT) biomaterials implanted into their tumors. The single function of these RT biomaterials is to ensure geometric accuracy during treatment. Recent studies have proposed that the inert biomaterials could be upgraded to ‘smart’ RT biomaterials, designed to do more than one function. Such smart biomaterials include next generation fiducial markers, brachytherapy spacers, and balloon applicators, designed to respond to stimulus and perform additional desirable functions like controlled delivery of therapy-enhancing payloads directly into the tumor sub-volume, while minimizing normal tissue toxicities. More broadly, smart RT biomaterials may include functionalized nanoparticles that can be activated to boost radiotherapy efficacy. This work reviews the rationale for smart radiotherapy biomaterials, the state-of-the-art in this emerging cross-disciplinary research area, challenges/opportunities for further research and development, and a purview of potential clinical applications. Applications covered include using smart RT biomaterials for boosting cancer therapy with minimal side effects, combining radiotherapy with immunotherapy or chemotherapy, reducing treatment time or healthcare costs, and other incipient applications.

Overexpression of BCR-ABL and P-glycoprotein (Pgp) are two of the known mechanisms of imatinib resistance. As combination therapy may allow to overcome drug resistance, we investigated the effect of combination treatment with imatinib and 17-allylamino-17-demethoxygeldanamycin (17-AAG), a heat-shock protein 90 (Hsp90) inhibitor, on different imatinib-sensitive and imatinib-resistant CML cell lines. In imatinib-sensitive cells, combination index (CI) values obtained using the method of Chou and Talalay indicated additive (CI ¼ 1) or marginally antagonistic (CI41) effects following simultaneous treatment with imatinib and 17-AAG. In imatinib-resistant cells both drugs acted synergistically (CIo1). In primary chronic-phase CML cells additive or synergistic effects of the combination of imatinib plus 17-AAG were discernible. Annexin V/propidium iodide staining showed that the activity of imatinib plus 17-AAG is mediated by apoptosis. Combination treatment with imatinib plus 17-AAG was more effective in reducing the BCR-ABL protein level than 17-AAG alone. Monotherapy with 17-AAG decreased P-glycoprotein activity, which may increase intracellular imatinib levels and contribute to the sensitization of CML cells to imatinib. The results suggest that combination of imatinib and 17-AAG may be useful to overcome imatinib resistance in a clinical setting.

No abstract

Adverse reactions in normal tissue after radiotherapy (RT) limit the dose that can be given to tumour cells. Since 80% of individual variation in clinical response is estimated to be caused by patient-related factors, identifying these factors might allow prediction of patients with increased risk of developing severe reactions. While inactivation of cell renewal is considered a major cause of toxicity in early-reacting normal tissues, complex interactions involving multiple cell types, cytokines, and hypoxia seem important for late reactions. Here, we review ‘omics’ approaches such as screening of genetic polymorphisms or gene expression analysis, and assess the potential of epigenetic factors, posttranslational modification, signal transduction, and metabolism. Furthermore, functional assays have suggested possible associations with clinical risk of adverse reaction. Pathway analysis incorporating different ‘omics’ approaches may be more efficient in identifying critical pathways than pathway analysis based on single ‘omics’ data sets. Integrating these pathways with functional assays may be powerful in identifying multiple subgroups of RT patients characterized by different mechanisms. Thus ‘omics’ and functional approaches may synergize if they are integrated into radiogenomics ‘systems biology’ to facilitate the goal of individualised radiotherapy.

Radiotherapy is a fundamental part of cancer treatment but its use is limited by the onset of late adverse effects in the normal tissue, especially radiation-induced fibrosis. Since the molecular causes for fibrosis are largely unknown, we analyse if epigenetic regulation might explain inter-individual differences in fibrosis risk. DNA methylation profiling of dermal fibroblasts obtained from breast cancer patients prior to irradiation identifies differences associated with fibrosis. One region is characterized as a differentially methylated enhancer of diacylglycerol kinase alpha (DGKA). Decreased DNA methylation at this enhancer enables recruitment of the profibrotic transcription factor early growth response 1 (EGR1) and facilitates radiation-induced DGKA transcription in cells from patients later developing fibrosis. Conversely, inhibition of DGKA has pronounced effects on diacylglycerol-mediated lipid homeostasis and reduces profibrotic fibroblast activation. Collectively, DGKA is an epigenetically deregulated kinase involved in radiation response and may serve as a marker and therapeutic target for personalized radiotherapy.

Summary. Peripheral blood progenitor cells (PBPC) can be mobilized using chemotherapy and granulocyte colonystimulating factor (G-CSF). We and others previously reported a correlation of steady-state PBPC counts and the PBPC yield during mobilization in a small group of patients. Here we present data on 100 patients (patients: 25 nonHodgkin's lymphoma (NHL), five Hodgkin's disease, 35 multiple myeloma (MM), 35 solid tumour) which enabled a detailed analysis of determinants of steady-state PBPC levels and of mobilization efficiency in patient subgroups. Previous irradiation (P ¼ 0·0034) or previous chemotherapy in patients with haematological malignancies (P ¼ 0·0062) led to a depletion of steady-state PB CD34 þ cells. A correlation analysis showed steady-state PB CD34 þ cells (all patients: r ¼ 0·52, P < 0·0001; NHL patients, r ¼ 0·69, P ¼ 0·0003; MM patients: r ¼ 0·66, P ¼ 0·0001) and PB colony-forming cells can reliably assess the CD34 þ cell yield in mobilized PB. In patients with solid tumour a similar trend was observed in mobilization after the first chemotherapy cycle (r ¼ 0·51, P ¼ 0·05) but not if mobilization occurred after the second or further cycle of a sequential doseintensified G-CSF-supported chemotherapy regimen, when premobilization CD34 þ counts were 18-fold elevated (P ¼ 0·004). When the patients with MM (r ¼ 0·63, P ¼ 0·0008) or with NHL (r ¼ 0·65, P ¼ 0·006) were analysed separately, a highly significant correlation of the steady-state PB CD34 þ cell count to the mean leukapheresis CD34 þ cell yield was found, whereas no correlation was observed for patients with a solid tumour. For patients with haematological malignancies estimates could be calculated which, at a specific steady-state PB CD34 þ cell count, could predict with a 95% probability a defined minimum progenitor cell yield. These results enable recognition of patients who mobilize PBPC poorly and may assist selection of patients for novel mobilization regimens.