Maintaining success, reducing treatment burden, focusing on survivorship: highlights from the third European consensus conference on diagnosis and treatment of germ-cell cancer

In November 2011, the Third European Consensus Conference on Diagnosis and Treatment of Germ-Cell Cancer (GCC) was held in Berlin, Germany. This third conference followed similar meetings in 2003 (Essen, Germany) and 2006 (Amsterdam, The Netherlands) [Schmoll H-J, Souchon R, Krege S et al. European consensus on diagnosis and treatment of germ-cell cancer: a report of the European Germ-Cell Cancer Consensus Group (EGCCCG). Ann Oncol 2004; 15: 1377-1399; Krege S, Beyer J, Souchon R et al. European consensus conference on diagnosis and treatment of germ-cell cancer: a report of the second meeting of the European Germ-Cell Cancer Consensus group (EGCCCG): part I. Eur Urol 2008; 53: 478-496; Krege S, Beyer J, Souchon R et al. European consensus conference on diagnosis and treatment of germ-cell cancer: a report of the second meeting of the European Germ-Cell Cancer Consensus group (EGCCCG): part II. Eur Urol 2008; 53: 497-513]. A panel of 56 of 60 invited GCC experts from all across Europe discussed all aspects on diagnosis and treatment of GCC, with a particular focus on acute and late toxic effects as well as on survivorship issues. The panel consisted of oncologists, urologic surgeons, radiooncologists, pathologists and basic scientists, who are all actively involved in care of GCC patients. Panelists were chosen based on the publication activity in recent years. Before the meeting, panelists were asked to review the literature published since 2006 in 20 major areas concerning all aspects of diagnosis, treatment and follow-up of GCC patients, and to prepare an updated version of the previous recommendations to be discussed at the conference. In addition, ∼50 E-vote questions were drafted and presented at the conference to address the most controversial areas for a poll of expert opinions. Here, we present the main recommendations and controversies of this meeting. The votes of the panelists are added as online supplements.

Interleukin-2 in combination with interferon-alpha and 5-fluorouracil for metastatic renal cell cancer

Recent clinical trials for the biological therapy of solid tumours have used recombinant human cytokines in combination with conventional chemotherapy. In patients with progressive metastatic renal cell carcinoma, we established a three-drug combination comprising interferon-alpha (IFN-alpha), interleukin-2 (IL-2) and 5-fluorouracil (5-FU), using a regimen which allows outpatient therapy. Treatment consisted of 8 weeks each of IFN-alpha [6-9 MU/m2 once to three times weekly subcutaneously (sc)] combined sequentially with IL-2 (5-20 MU/m2 thrice weekly sc for 4 weeks) and 5-FU [750 mg/m2 intravenously (i.v.) weekly for 4 weeks]. Among the first 35 patients treated, there were 4 complete (11.4%) and 13 partial responders (37.1%), with an overall objective response rate of 48.6% (95% confidence interval 32-66%). Regressions occurred in local relapse, in lung, lymph node, bone, pleural, renal and thyroid metastases. Median response duration was calculated at 7+ months. An additional 13 patients (37.1%) were stable throughout therapy and thereafter (median of 6+ months). Response rate of this three-drug combination regimen compared favourably with single agent IFN-alpha (objective response rate approximately 16%) and against the sc IFN-alpha/IL-2 combination (objective response rate approximately 28%). Systemic toxicity was mild to moderate with no severe 5-FU-related mucositis and no dose-limiting adverse effects of sc IL-2. While the exact mechanisms of the potentially additive or synergistic effects of 5-FU and IFN-alpha/IL-2 remain to be established in more detail, it appears that the sequential use of IFN-alpha/IL-2 and IFN-alpha/5-FU in metastatic renal carcinoma further enhances the therapeutic index of IFN-alpha/IL-2-based biological therapy. Based on the present data, combined biochemotherapy may be a promising new approach to the therapy of advanced renal cancer.

Relationship between capitulum size and pre-dispersal seed predation by insect larvae in common Asteraceae

The evolution of a showy floral display as an advertisement to pollinators could simultaneously advertise the availability of resources to pre-dispersal seed-predators. The hypotheses tested here are that the incidence of seed predation by bud-infesting insect larvae in capitula of Asteraceae is positively related to (1) capitulum size among species, (2) capitulum size within species, (3) capitulum lifespan, and (4) the degree of flowering asynchrony on individual plants. Three populations of each of 20 common herbaceous species of Asteraceae from disturbed ground and grassland habitats were monitored for the presence of pre-dispersal, seed-eating insect larvae. Mean capitulum size (receptacle width) of each species was measured. In a sub-set of eight species, individual capitula were tagged to determine their flowering phenology and lifespan (from anthesis to seed shedding). From these data an index of flowering synchrony on individual plants was derived. Among species, the incidence of larval infestation increased with capitulum size. Small-flowered species such as Achillea millefolium were largely free of bud-infesting larvae, whilst large-flowered species such as Arctium minus were heavily infested. In three cases investigated in greater detail, bud infestation was found to increase with capitulum size within species, suggesting a potential for natural selection to favour smaller capitula. No relationship was found between infestation levels and either capitulum lifespan or degree of flowering synchrony, and there was no evidence that the relationship between capitulum size and infestation was confounded by correlations with these other features. The results support hypotheses 1 and 2, but not 3 and 4. It is suggested that the characteristic capitulum size of each species may represent a trade-off between the opposing selection pressures of pollinators and pre-dispersal seed predators.

Preclinical and clinical activity of sunitinib in patients with cisplatin-refractory or multiply relapsed germ cell tumors: a Canadian Urologic Oncology Group/German Testicular Cancer Study Group cooperative study

BACKGROUND

The objective of the study was to investigate the activity of sunitinib in a cell line model and subsequently in patients with cisplatin-refractory or multiply relapsed germ cell tumors (GCT).

METHODS

The effect of sunitinib on cell proliferation in cisplatin-sensitive and cisplatin-refractory GCT cell lines was evaluated after 48-h sunitinib exposure by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay, and IC(50) (concentration that causes 50% inhibition of growth) doses were determined. Sunitinib was subsequently administered at a dose of 50 mg/day for 4 weeks followed by a 2-week break to 33 patients using a Simon two-stage design.

RESULTS

Sunitinib demonstrated comparable dose-dependent growth inhibition in cisplatin-sensitive and cisplatin-resistant cell lines, with IC(50) between 3.0 and 3.8 μM. Patient characteristics were as follows: median of 2 (1-6) cisplatin-containing regimens; high-dose chemotherapy 67%; late relapse 33%; and cisplatin refractory or absolute cisplatin refractory 54%. Toxic effects included fatigue (39%), anorexia (21%), diarrhea (27%), mucositis (45%), nausea (33%), hand-foot syndrome (12%), dyspepsia (27%), and skin rash (18%). No unexpected side-effects were observed. Thirty -two of 33 patients were assessable for response. Three confirmed partial responses (PRs) and one unconfirmed PR were seen for a total response rate of 13%. Median progression-free survival (PFS) was 2 months, with a 6-month PFS rate of 11%.

CONCLUSIONS

Sunitinib shows in vitro activity in cisplatin-resistant GCT cell lines. Modest clinical activity in heavily pretreated GCT patients was observed.

Novel therapeutic approach: ligands for PPARgamma and retinoid receptors induce apoptosis in bcl-2-positive human breast cancer cells

Effective treatment of tumors is often associated with activation of the endogenous apoptosis pathways. We have studied eight breast cancer cell lines (MCF-7, BT20, BT474, MDA-MB-231, MDA-MB-436, SKBR3, T-47D, ZR-75-1) possessing a variety of genetic defects. The clonogenic growth of breast cancer cell lines was inhibited by a ligand for PPARgamma (troglitazone, TGZ) combined with a ligand for either retinoid X receptor (RXR) (LG10069) (4/8 cell lines), RAR (ATRA) (5/8 cell lines) or RAR/RXR and RXR/RXR (9-cis-RA) (5/8 cell lines) independent of their expression of bcl-2, bag-1, ERalpha, and p53. The cell lines (MCF-7, T-47D, ZR-75-1), which expressed both BRCA1 and p27, were extremely sensitive to the inhibitory effect of the combination of TGZ and either ATRA or 9-cis-RA (ED90, 2-5 x 10(-11) M). However, only MCF-7, MDA-MB-231, and ZR-75-1 cells, which expressed a high level of bcl-2 protein, underwent apoptosis when exposed to the combination of TGZ and either ATRA or 9-cis-RA. Importantly, this effect was independent of expression levels of p53, ERalpha, HER-2/neu, bag-1, and BRCA1. Therefore, the combination of ligands for PPARgamma and retinoid receptors may have a therapeutic role for breast cancer.

Two independent receptors allow selective target lysis by T cell clones

Dimethylbenzanthracene-induced P1 sarcoma cells induce P1-specific antibodies in syngeneic DA rats. Antiidiotypic antibodies of specificity DA anti-(DA anti-P1) were induced against the tumor-specific antibodies and used to restimulate P1-primed DA T cells in vitro. Using antiidiotypic antibodies and T cell growth factor, P1-specific cytotoxic DA T cell clones were established by limiting dilution and kept in vitro. Two of these clones acquired during culture periods in addition to the P1 specificity lytic activity towards natural killer (NK) targets YAC-1 or K562. Cold target inhibition experiments showed that the very same cytotoxic T cells kill P1 and NK targets. Antiidiotypic antibodies of specificity DA anti-(DA anti-P1) inhibited cytotoxicity against P1 but not against YAC-1 or K562. We conclude that two independent receptors are located on these double-reactive T cell clones, one that is idiotypic and antigen-specific, and another displaying the binding profile of NK cells.

Early plant growth: identifying the end point of the seedling phase

•  Despite the importance of seedling establishment in plant biology, there is no consensus on what constitutes a 'seedling'. Here we examined aspects of early plant development that could be used to mark the transition from the seedling to the postseedling phase. •  Using a hypogeal species (pea, Pisum sativum) and an epigeal species (sunflower, Helianthus annuus), we investigated whether the utilization of cotyledon-stored mineral nutrients coincides with any changes in relative growth rate (RGR). We also examined how the timing of cotyledon removal at different points during early development affected subsequent growth. •  For both species, the timing of RGR_max , the exhaustion of cotyledon reserves, and the attainment of independence from cotyledons all roughly coincided (though exhaustion of seed reserves was not observed in the epigeal species because the cotyledons absorbed external nutrients). •  We conclude that because the point of attainment of RGR_max is a distinctly identifiable event, it is a more reliable marker for defining the end of the seedling stage than either the exhaustion of mineral reserves, or the cessation of dependence on cotyledon reserves.

Chromosomal instability during neurogenesis in Huntington's disease

Huntington's disease (HD) is a fatal neurodegenerative disease caused by expansion of CAG repeats in the Huntingtin gene (HTT). Neither its pathogenic mechanisms nor the normal functions of HTT are well understood. To model HD in humans, we engineered a genetic allelic series of isogenic human embryonic stem cell (hESC) lines with graded increases in CAG repeat length. Neural differentiation of these lines unveiled a novel developmental HD phenotype: the appearance of giant multinucleated telencephalic neurons at an abundance directly proportional to CAG repeat length, generated by a chromosomal instability and failed cytokinesis over multiple rounds of DNA replication. We conclude that disrupted neurogenesis during development is an important, unrecognized aspect of HD pathogenesis. To address the function of normal HTT protein we generated HTT^+/- and HTT^-/- lines. Surprisingly, the same phenotype emerged in HTT^-/- but not HTT^+/- lines. We conclude that HD is a developmental disorder characterized by chromosomal instability that impairs neurogenesis, and that HD represents a genetic dominant-negative loss of function, contrary to the prevalent gain-of-toxic-function hypothesis. The consequences of developmental alterations should be considered as a new target for HD therapies.

Changes in germinability, ABA content and ABA embryonic sensitivity in developing seeds of Sorghum bicolor (L.) Moench. induced by water stress during grain filling

The effect of intermittent water stress during grain filling on the germinability of developing seeds of S. bicolor was investigated. The drought treatment was imposed in cycles within the maturation period by withholding water for 5-6 days, rewatering at the end of each drought cycle and withholding water again. Changes in abscisic acid (ABA) content and embryonic sensitivity to ABA in the maturing seeds were also monitored in order to find out if there were any parallel changes with seed germinability resulting from drought conditions. Seeds developing in plants subjected to drought showed a high level of germinability earlier in the maturation period than did control seeds; consequently, they were less resistant to pre-harvest sprouting as shown when panicles were exposed to high humidity conditions. Very high levels of ABA accumulated in the early stages of development in seeds maturing on water-stressed mother plants; however. ABA content fell markedly when the seeds stopped growing, and remained significantly below those recorded in control seeds until the end of the maturation period. Development under drought conditions decreased the sensitivity of the isolated embryo to exogenous ABA by about 10-fold. The good agreement found between germinability, endogenous ABA concentrations and embryo sensitivity to ABA at different stages of development, suggests a key role for ABA as a major inhibitor of precocious germination and shows that changes in germinability caused by water stress during grain filling are likely to be related to changes in ABA pool size in the developing seed.

Treatment of everolimus-resistant metastatic renal cell carcinoma with VEGF-targeted therapies

Background:

Treatment of everolimus-resistant disease remains largely undefined in metastatic renal cell carcinoma (mRCC). We report on 40 patients (pts) who receive systemic treatment after failure of everolimus.

Patients and methods:

Forty pts received sunitinib (n=19), sorafenib (n=8), dovitinib (n=10) or bevacizumab/interferon (n=3) after failure of everolimus. Median progression-free survival (PFS), overall survival (OS) and best tumour response (according to Response Evaluation Criteria In Solid Tumors) were analysed retrospectively. Kaplan–Meier, log-rank test and Cox regression analyses were used to estimate or predict OS and PFS.

Results:

Treatment of everolimus-resistant disease was associated with a PFS of 5.5 months. (range 0.4–22.3) and an objective partial remission (PR) in 4 pts (10%) and stable disease (SD) in 22 pts (55%). In univariate analyses, first-line treatment with sorafenib was the only variable to correlate with a prolonged PFS of treatment in everolimus-resistant disease (P=0.036). However, its significance as a predictive marker for subsequent therapy could not be verified in multivariate analyses.

Conclusions:

Vascular endothelial growth factor targeted therapy shows promising activity in everolimus-resistant metastatic renal cancer and warrants further studies.

A peptide analogue to a fusion domain within photoreceptor peripherin/rds promotes membrane adhesion and depolarization

Photoreceptor peripherin/rds promotes membrane fusion, through a putative fusion domain located within the C-terminus (Boesze-Battaglia et al., Biochemistry 37 (1998) 9477-9487). A peptide analogue to this region, PP-5, competitively inhibits peripherin/rds mediated fusion in a cell free assay system. To characterize how this region is involved in the fusion process we investigated two of the individual steps in membrane fusion, membrane adhesion and membrane destabilization inferred from depolarization studies. Membrane depolarization was measured as the collapse of a valinomycin induced K(+) diffusion potential in model membranes, using a potential sensitive fluorescent probe, diS-C(2)-5. PP-5 induced membrane depolarization in a concentration dependent manner. PP-5 has been shown by Fourier transform infrared spectroscopy to be an amphiphilic alpha-helix. Therefore, the requirement for an amphiphilic alpha-helix to promote depolarization was tested using two mutant peptides designed to disrupt either the amphiphilic nature of PP-5 (PP-5AB) or the alpha-helical structure (PP-5HB). PP-5AB inhibited PP-5 induced depolarization when added in an equimolar ratio to PP-5. Neither mutant peptide alone or in combination with PP-5 had any effect on calcium dependent vesicle aggregation. Using non-denaturing gel electrophoresis and size exclusion chromatography techniques PP-5 was shown to form a tetrameric complex. Equimolar mixtures of PP-5 and PP-5AB formed a heterotetramer which was unable to promote membrane depolarization. The hypothesis that PP-5 tetramers promote membrane depolarization is consistent with the calculated Hill coefficient of 3.725, determined from a Hill analysis of the depolarization data.

Optimizing Production of Antigens and Fabs in the Context of Generating Recombinant Antibodies to Human Proteins

We developed and optimized a high-throughput project workflow to generate renewable recombinant antibodies to human proteins involved in epigenetic signalling. Three different strategies to produce phage display compatible protein antigens in bacterial systems were compared, and we found that in vivo biotinylation through the use of an Avi tag was the most productive method. Phage display selections were performed on 265 in vivo biotinylated antigen domains. High-affinity Fabs (<20nM) were obtained for 196. We constructed and optimized a new expression vector to produce in vivo biotinylated Fabs in E. coli. This increased average yields up to 10-fold, with an average yield of 4 mg/L. For 118 antigens, we identified Fabs that could immunoprecipitate their full-length endogenous targets from mammalian cell lysates. One Fab for each antigen was converted to a recombinant IgG and produced in mammalian cells, with an average yield of 15 mg/L. In summary, we have optimized each step of the pipeline to produce recombinant antibodies, significantly increasing both efficiency and yield, and also showed that these Fabs and IgGs can be generally useful for chromatin immunoprecipitation (ChIP) protocols.

Invasive behavior of mouse sarcoma cells is inhibited by blocking a 37,000-dalton plasma membrane glycoprotein with Fab fragments

Abercrombie 's confronted explant technique was used to study the role of tumor surface antigens in malignant invasion. Plasma membranes were isolated from mouse sarcoma cells ( FS9 ) and a mouse cell line (L929) of the same H-2 haplotype. FS9 cells are highly invasive when confronted with chicken heart fibroblasts, whereas the L929 cells are not [ Abercrombie , M. (1979) Nature (London) 281, 259-262]. The FS9 plasma membranes contained significantly higher concentrations of a 37,000-dalton glycoprotein. When antiserum directed against FS9 plasma membranes was preabsorbed with L929 cells, the antibodies remaining reacted predominantly with the 37,000-dalton antigen. Fab fragment prepared from the preabsorbed antiserum inhibited the invasion of chicken heart fibroblasts by FS9 cells. Fab prepared from a monoclonal antibody directed against the 37,000-dalton antigen also inhibited invasivity , whereas monoclonal antibodies reacting with two other FS9 cell surface antigens did not. The results imply a relationship between the increased concentration of the 37,000-dalton glycoprotein on the surface of the FS9 cells and their invasivity .

Studies of the invasiveness of the chemically induced mouse sarcoma FS9. I. Monoclonal antibodies to a 37,000 dalton membrane glycoprotein inhibit invasion of fibroblasts in vitro

Monoclonal antibodies against the mouse sarcoma FS9 were prepared. Antibodies recognizing a 37,000 dalton glycoprotein on FS9 tumor cells inhibit invasion by FS9 sarcoma cells of chicken heart fibroblasts in vitro as assessed by Abercrombie's confronted explant assay. Antibodies to other membrane proteins of FS9 tumor cells failed to inhibit invasiveness of FS9 sarcoma cells. The 37,000 dalton glycoprotein, which is neither a histocompatibility antigen nor a gp37 glycoprotein of Rous sarcoma virus nor the MEP described by Gottesman, is present on the surface and in the cytoplasm of FS9 sarcoma cells. The plasma membrane of the non-invasive mouse cell line L929 contains only low concentrations of the 37,000 dalton antigen. Hence, a relationship apparently exists between the increased concentration of this protein on the surface of FS9 cells and their invasiveness.

Lack of therapeutic efficacy of tamoxifen in advanced renal cell carcinoma

In the present study, we treated a total of 62 patients with advanced renal cell carcinoma with high-dose tamoxifen (100 mg/m2/day). Patients were treated in the outpatient setting, and were evaluated 8-12 weeks after initiation of therapy or sooner, when clinical disease progression was evident; a total of 15 patients were seen at short regular intervals for evaluation of clinical and laboratory parameters. Of these 62 patients, 59 were evaluable for treatment response, survival and systemic toxicity. One partial remission was achieved (1.7%; 95% confidence interval, 0.04-9.09%), response duration was 3 months. 10 patients presented with stable disease, for a median duration of 4.0 months, and 48 patients exhibited disease progression upon and after therapy. Systemic toxicity was significant; severe fatigue occurred in 5% of patients, and moderate anaemia, dyspnea, alopecia and malaise in almost 20% of patients. Antineoplastic efficacy of tamoxifen at this dosage in this cohort of patients was at best marginal and well in the range associated with the occurrence of spontaneous remissions. Toxicity was substantial, and it was not balanced by therapeutic benefit. This is consistent with the known lack of therapeutic efficacy of endocrine therapy in advanced renal cell carcinoma.