The soft X-ray monochromator at the SASE3 beamline of the European XFEL: from design to operation

The SASE3 soft X-ray beamline at the European XFEL has been designed and built to provide experiments with a pink or monochromatic beam in the photon energy range 250-3000 eV. Here, the focus is monochromatic operation of the SASE3 beamline, and the design and performance of the SASE3 grating monochromator are reported. The unique capability of a free-electron laser source to produce short femtosecond pulses of a high degree of coherence challenges the monochromator design by demanding control of both photon energy and temporal resolution. The aim to transport close to transform-limited pulses poses very high demands on the optics quality, in particular on the grating. The current realization of the SASE3 monochromator is discussed in comparison with optimal design performance. At present, the monochromator operates with two gratings: the low-resolution grating is optimized for time-resolved experiments and allows for moderate resolving power of about 2000-5000 along with pulse stretching of a few to a few tens of femtoseconds RMS, and the high-resolution grating reaches a resolving power of 10 000 at the cost of larger pulse stretching.

Performance of a cryo-cooled crystal monochromator illuminated by hard X-rays with MHz repetition rate at the European X-ray Free-Electron Laser

Due to the high intensity and MHz repetition rate of photon pulses generated by the European X-ray Free-Electron Laser, the heat load on silicon crystal monochromators can become large and prevent ideal transmission in Bragg diffraction geometry due to crystal deformation. Here, we present experimental data illustrating how heat load affects the performance of a cryogenically cooled monochromator under such conditions. The measurements are in good agreement with a depth-uniform model of X-ray dynamical diffraction taking beam absorption and heat deformation of the crystals into account.

The SASE1 X-ray beam transport system

SASE1 is the first beamline of the European XFEL that became operational in 2017. It consists of the SASE1 undulator system, the beam transport system, and the two scientific experiment stations: Single Particles, Clusters, and Biomolecules and Serial Femtosecond Crystallography (SPB/SFX), and Femtosecond X-ray Experiments (FXE). The beam transport system comprises mirrors to offset and guide the beam to the instruments and a set of X-ray optical components to align, manipulate and diagnose the beam. The SASE1 beam transport system is described here in its initial configuration, and results and experiences from the first year of user operation are reported.

Die Markierung von Erythrozyten mit radioaktiven Indiumisotopen

Es wird eine Methode zur Markierung von Erythrozyten mit radioaktiven Indiumisotopen beschrieben. Die In-vitro-Markierung erfolgt unter Zusatz von in Trispuffer gelöstem Azetylazeton. Die Markierungsausbeute und die Stabilität der Markierung sind mit den Werten, die mit 51Cr erzielt werden, voll vergleichbar. Die Auswahl unter verschiedenen radioaktiven Indiumisotopen erlaubt die Anpassung der nuklearmedizinischen Untersuchungen an die jeweilige Frage Stellung, die mit einer Erythrozyten-Markierung verbunden sind: Bestimmung des Erythrozytenvolumens, Nachweis eines enteralen Blutverlustes sowie die szintigrafische Darstellung des Blutpools und der Milz. Der Ersatz von 51Cr durch die verschiedenen Indium-Isotope bringt eine nicht zu vernachlässigende Dosisverminderung für den Patienten mit sich.

Prä- und intraoperative Volumenbestimmung bei Craniopharyngiomcysten

Die richtige Dosierung des 90Y für die intracavitäre Therapie bei monocystischen Craniopharyngiomen setzt die genaue Bestimmung des Cystenvolumens voraus. Der intraoperativen Volumenbestimmung mittels Radionuklid-Verdünnungsanalyse wurde die präoperative Volumetrie mit Hilfe von Computertomographieaufnahmen gegenübergestellt. Die Ergebnisse beider Verfahren zeigten eine gute übereinstimmung. Zur frühzeitigen Erkennung von Komplikationen werden Aufnahmen mit der Gammakamera als notwendig erachtet.

Growth of nano-dots on the grazing-incidence mirror surface under FEL irradiation

A new phenomenon on X-ray optics surfaces has been observed: the growth of nano-dots (40-55 nm diameter, 8-13 nm height, 9.4 dots µm(-2) surface density) on the grazing-incidence mirror surface under irradiation by the free-electron laser (FEL) FLASH (5-45 nm wavelength, 3° grazing-incidence angle). With a model calculation it is shown that these nano-dots may occur during the growth of a contamination layer due to polymerization of incoming hydrocarbon molecules. The crucial factors responsible for the growth of nano-dots in the model are the incident peak intensity and the reflection angle of the beam. A reduction of the peak intensity (e.g. replacement of the FEL beam by synchrotron radiation) as well as a decrease of the incident angle by just 1° (from 3° to 2°) may result in the total disappearance of the nano-dots. The model calculations are compared with surface analysis of two FLASH mirrors.

Comparative study of the X-ray reflectivity and in-depth profile of a-C, B₄C and Ni coatings at 0.1-2 keV

The use of soft X-rays near the carbon edge of absorption (270-300 eV) greatly enhances studies in various branches of science. However, the choice of reflecting coatings for mirrors operating in free-electron and X-ray free-electron laser (FEL and XFEL) beamlines in this spectral range is not so evident and experimental justifications of the mirror efficiency are rather limited. In the present paper it is demonstrated experimentally that the reflectivity of B4C- and Ni-coated grazing-incidence mirrors is high enough for their operation in FEL or XFEL beamlines near the carbon K-edge of absorption. The minimal reflectivity of both mirrors proves to exceed 80% near the carbon absorption edge at a grazing angle of 0.6°. An in-depth profile of the chemical elements composing the reflecting coatings is reconstructed based on analysis of a set of reflectivity curves measured versus the grazing angle at different photon energies in the soft X-ray spectral region. This allows us to predict correctly the mirror reflectivity at any X-ray energy and any grazing angle.

Enhanced albumin uptake by rat tumors

Albumin dominates the nitrogen and energy resources in blood. However, only limited data is available on its accumulation and catabolism by tumors. This was caused by the lack of suitable radiolabels for long-term follow-up of protein catabolism in vivo. Conventional radiolabels like radioiodine are metabolically unstable. After lysosomal degradation diffusible tracer residues are rapidly released from catabolic sites, Tumors with high metabolic activity evade detection. To study the uptake of rat serum albumin (RSA) by tumors a conventional radioiodine label and two residualizing radiolabels were chosen. It is known that residualizing I-131-tyramine-deoxisorbitol and In-111-DTPA protein labels remain trapped at catabolic sites after lysosomal degradation of their carrier proteins. We were able to show by scintigraphy and after organ removal that a Walker-256 carcinosarcoma with a turner size of about 5% of the body weight accumulated more than 20% of the initially injected dose of a In-111-DTPA-RSA within 24 h. Tumor uptake rates for albumin exceeded those of the kidneys by about 4 times, and those of the liver by about 3 times. It was estimated that about one out of two albumin molecules trapped by an ovarian-342 tumor must have been degraded during 72 h. High uptake and degradation rates would make albumin an alternative nitrogen and energy source for these tumors. Although an unfavorable time-frame limits the use of residualizingly labeled albumin for scintigraphic tumor diagnosis in man, albumin might be an interesting carrier for delivering covalently attached chemotherapeutic agents into tumors by an alternative lysosomal route.

The soft x-ray instrument for materials studies at the linac coherent light source x-ray free-electron laser

The soft x-ray materials science instrument is the second operational beamline at the linac coherent light source x-ray free electron laser. The instrument operates with a photon energy range of 480-2000 eV and features a grating monochromator as well as bendable refocusing mirrors. A broad range of experimental stations may be installed to study diverse scientific topics such as: ultrafast chemistry, surface science, highly correlated electron systems, matter under extreme conditions, and laboratory astrophysics. Preliminary commissioning results are presented including the first soft x-ray single-shot energy spectrum from a free electron laser.

Coherence properties of individual femtosecond pulses of an x-ray free-electron laser

Measurements of the spatial and temporal coherence of single, femtosecond x-ray pulses generated by the first hard x-ray free-electron laser, the Linac Coherent Light Source, are presented. Single-shot measurements were performed at 780 eV x-ray photon energy using apertures containing double pinholes in "diffract-and-destroy" mode. We determined a coherence length of 17  μm in the vertical direction, which is approximately the size of the focused Linac Coherent Light Source beam in the same direction. The analysis of the diffraction patterns produced by the pinholes with the largest separation yields an estimate of the temporal coherence time of 0.55 fs. We find that the total degree of transverse coherence is 56% and that the x-ray pulses are adequately described by two transverse coherent modes in each direction. This leads us to the conclusion that 78% of the total power is contained in the dominant mode.

Nanofocusing of hard X-ray free electron laser pulses using diamond based Fresnel zone plates

A growing number of X-ray sources based on the free-electron laser (XFEL) principle are presently under construction or have recently started operation. The intense, ultrashort pulses of these sources will enable new insights in many different fields of science. A key problem is to provide x-ray optical elements capable of collecting the largest possible fraction of the radiation and to focus into the smallest possible focus. As a key step towards this goal, we demonstrate here the first nanofocusing of hard XFEL pulses. We developed diamond based Fresnel zone plates capable of withstanding the full beam of the world's most powerful x-ray laser. Using an imprint technique, we measured the focal spot size, which was limited to 320 nm FWHM by the spectral band width of the source. A peak power density in the focal spot of 4×10¹⁷ W/cm² was obtained at 70 fs pulse length.

Time-resolved investigation of nanometer scale deformations induced by a high flux x-ray beam

We present results of a time-resolved pump-probe experiment where a Si sample was exposed to an intense 15 keV beam and its surface monitored by measuring the wavefront deformation of a reflected optical laser probe beam. By reconstructing and back propagating the wavefront, the deformed surface can be retrieved for each time step. The dynamics of the heat bump, build-up and relaxation, is followed with a spatial resolution in the nanometer range. The results are interpreted taking into account results of finite element method simulations. Due to its robustness and simplicity this method should find further developments at new x-ray light sources (FEL) or be used to gain understanding on thermo-dynamical behavior of highly excited materials.

Observation of phonons with resonant inelastic x-ray scattering

Phonons, the quantum mechanical representation of lattice vibrations, and their coupling to the electronic degrees of freedom are important for understanding thermal and electric properties of materials. For the first time, phonons have been measured using resonant inelastic x-ray scattering (RIXS) across the Cu K-edge in cupric oxide (CuO). Analyzing these spectra using an ultra-short core-hole lifetime approximation and exact diagonalization techniques, we can explain the essential inelastic features. The relative spectral intensities are related to the electron-phonon coupling strengths.

Transverse acoustic excitations in liquid Ga

The transverse acoustic excitation modes were detected by inelastic x-ray scattering in liquid Ga in the Q range above 9 nm(-1) although liquid Ga is mostly described by a hard-sphere liquid. An ab initio molecular dynamics simulation clearly supports this finding. From the detailed analysis for the S(Q,omega) spectra with a good statistic quality, the lifetime of 0.5 ps and the propagating length of 0.4-0.5 nm can be estimated for the transverse acoustic phonon modes, which may correspond to the lifetime and size of cages formed instantaneously in liquid Ga.

The possibility of transverse excitation modes in liquid Ga

The dynamic structure factor S(Q,ω) of liquid Ga was measured at 100 °C using a high resolution inelastic x-ray scattering (IXS) spectrometer at 3-ID-C/APS. The spectra obtained clearly demonstrate the existence of longitudinal propagating modes at small Q values, like a previous IXS result at 42 °C obtained by Scopigno et al and an inelastic neutron scattering (INS) one at 47 °C obtained by Bove et al, but unlike an INS study at 57 °C by Bermejo et al. The dispersion relation of the excitations deviates positively from the hydrodynamic prediction by about 13%. There are two new findings from this experiment. Firstly, an additional lower energy excitation is necessary to reproduce S(Q,ω) spectra in the Q range beyond 10 nm(-1), in agreement with the result of a first-principles molecular dynamic simulation, which may indicate a transverse acoustic mode in this peculiar liquid metal. Secondly, the quasielastic line comprises a Gaussian contribution at Q values near the first maximum in S(Q), which may indicate the existence of short-lived covalent correlation in liquid Ga with a lifetime of 0.39 ps.

A 2 m inelastic X-ray scattering spectrometer at CMC-XOR, Advanced Photon Source

The design and commissioning of an inelastic X-ray scattering instrument at CMC-XOR at the Advanced Photon Source is reported. The instrument features a 2 m vertical-scattering arm with a novel counterweight design to reduce the twisting moment as the arm is moved in the scattering plane. A Ge(733) spherical analyzer was fabricated and an overall resolution of 118 meV (FWHM) was obtained with a Si(444) monochromator and a Si(111) pre-monochromator. Early results from a representative cuprate, La(2)CuO(4), are reported.

Oblimersen (O) in combination with docetaxel (T), adriamycin (A), and cyclophosphamide (C) as neoadjuvant systemic therapy (NST) in primary breast cancer (PBC): Final results of a multicentric phase I study

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Background: The Bcl-2 downregulator O in combination with standard cytotoxic chemotherapy leads to synergistic antitumor effects in preclinical trials. To evaluate maximum tolerated dose (MTD), safety and preliminary efficacy of O in combination with TAC as NST in PBC we performed a multicentric phase I study. Methods: Previously untreated patients with PBC T2–4a-c N0–3 M0 received escalating doses of O as a 24 hour continuous infusion on day (d) 1–7 in combination with T 75mg/m2, A 50mg/m2 and C 500 mg/m2 on day 5 followed by five three weekly cycles of TAC without O. Results: A total of twenty-eight patients with a median age of 50 years were enrolled. 61% of tumors were T2, 43% grade 3, 68% ductal-invasive, and 64% hormone receptor positive. Patients received O in a dose of 3 mg/kg/d (cohort I, 9 patients), 5 mg/kg/d (II, 9 patients), and 7 mg/kg/d (III, 10 patients), respectively. No dose-limiting toxicity occurred. Most common adverse events [all National Cancer Institute-Common Toxicity Criteria (NCI-CTC) grade = 2] were fatigue, nausea, alopecia, headache and flue-like symptoms observed in 78% (I), 89% (II), and 90% (III) of patients, respectively. Following OTAC the most severe hematological toxicity was neutropenia (NCI-CTC grade 1–2/3/4) which developed in 0/0/56% of patients (I), 11/0/56% of patients (II), and 20/20/50% of patients (III), respectively. At least 50% reduction in tumor volume was oberved in 14 patients. Five patients (18%) achieved a pathologic complete response (3 patients in cohort I, 2 patients in cohort II). Conclusions: O up to a dose of 7 mg/kg/d given as a 24 hour infusion on day 1–7 can be safely administered in combination with standard TAC on day 5 as NST in patients with PBC. The preliminary efficacy warrants further evaluation of this combination in a randomised trial.

No significant financial relationships to disclose.

Formation of a new dynamical mode in -uranium observed by inelastic x-ray and neutron scattering

Phonon dispersion curves were obtained from inelastic x-ray and neutron scattering measurements on alpha-uranium single crystals at temperatures from 298 to 573 K. Both measurements showed a softening and an abrupt loss of intensity in the longitudinal optic branch along [00zeta] above 450 K. Above the same temperature a new dynamical mode of comparable intensity emerges along the [01zeta] zone boundary with energy near the top of the phonon spectrum. The new mode forms without a structural transition but coincides with an anomaly in the mechanical deformation behavior. We argue that the mode is an intrinsically localized vibration and formed as a result of a strong electron-phonon interaction.

Excitations of lithium ammonia complexes studied by inelastic x-ray scattering

We have carried out high-resolution inelastic x-ray scattering measurements of the excitations of lithium dissolved in ammonia. The incident x-ray energy was 21.6 keV and the resolution was about 2 meV. Several different excitations are observed in the energy range of 0-60 meV (0-500 cm(-1)). In addition to acoustic phonons at low energies, we see excitations that are associated with vibrations of Li(NH3)4+ complexes. We examined these excitations as a function of momentum transfer, lithium concentration, temperature, and state of the system (solid versus liquid). Data are compared with Hartree-Fock and density-functional theory calculations of the excitations of this complex, which agree well with the measured excitation energies.

Albumin-coupled methotrexate (MTX-HSA) is a new anti-arthritic drug which acts synergistically to MTX

OBJECTIVE

To evaluate the anti-arthritic effects of the new inflammation-targeted drug MTX-HSA and to investigate whether peripheral blood mononuclear cells (PBMC) are potential target cells for albumin-mediated drug delivery.

METHODS

The murine model of collagen-induced arthritis (CIA) was used to measure the anti-arthritic effect of MTX, MTX-HSA or a combination of both (n = 30 to 35 per group). In addition, the uptake of fluorescence-labelled albumin (AFLc-HSA) in PBMC of 14 patients with RA was measured by fluorescence-activated cell sorting (FACS).

RESULTS

In equivalent doses of 7.5 mg/kg intravenously (IV) twice a week, MTX-HSA is significantly (P<0.02) superior to MTX in inhibiting the development of CIA and reducing the joint count as well as the number of affected paws. When given in lower doses as combination therapy, both drugs act synergistically (P<0.03). A mean of 96, 72 and 64% of the CD14-, CD16- and CD20-positive cells from peripheral blood of rheumatoid arthritis (RA) patients showed an uptake of albumin after incubation with AFLc-HSA in vitro. This finding was not significantly different in comparison to healthy controls. In contrast, the number of CD3-positive cells taking up albumin is increased significantly in RA patients in comparison to controls (26.3 +/- 12.9% s.d. vs 11.6 +/- 7.3% s.d.; P = 0.005).

CONCLUSION

The data show that the effectiveness of MTX-HSA in CIA is superior to MTX and that both drugs act synergistically. In addition, albumin appears to be taken up by peripheral blood cells, suggesting that they might be one of the potential target cells of this novel anti-arthritic treatment approach.

Microscopic dynamics of liquid aluminum oxide

Collective excitations have been observed in liquid aluminum oxide at high temperatures by combining a containerless sample environment with inelastic x-ray scattering. The excitation spectra show a well-defined triplet peak structure at lower wave vectors Q (1 to 6 nanometers-1) and a single quasi-elastic peak at higher Q. The high-Q spectra are well described by kinetic theory. The low-Q spectra require a frequency-dependent viscosity and provide previously unknown experimental constraints on the behavior of liquids at the interface between atomistic and continuum theory.

Magnetic resonance imaging of nude mice with heterotransplanted high-grade squamous cell carcinomas: use of a low-loaded, covalently bound Gd-Hsa conjugate as contrast agent with high tumor affinity

RATIONALE

Malignant tumors often show an increased uptake and metabolism of plasma proteins, especially albumin.

OBJECTIVES

Determine whether the accumulation of low loaded Gd-albumin improves visualization of malignant tumors by MRI.

METHODS

Twelve nude mice with heterotransplanted squamous cell carcinomas were studied. The signal intensity of tumor, blood, liver, kidney and muscle tissue was studied in MR images after application of Gd-albumin during a period of 144 hours. MRI results were histologically correlated after simultaneously injection of Gd- and fluorescein-labeled albumins in 9 nude mice.

RESULTS

Although liver and kidney had a maximum increase in signal intensity within 30 minutes, tumors showed a delayed 51% increase in the 24 hours after application. Histologic and fluorescence evaluation demonstrated albumin localization in tumors predominantly in stroma and necroses.

CONCLUSIONS

Gd-albumin is efficiently accumulated in SCC transplants. MRI with low loaded Gd-albumin may offer relevant opportunities for recognizing tumors sensitive to a therapy with cyostic drug-labeled albumins.

Comparison of the in vivo efficiency of photofrin II-, mTHPC-, mTHPC-PEG- and mTHPCnPEG-mediated PDT in a human xenografted head and neck carcinoma

BACKGROUND AND OBJECTIVE

One of the approaches to enhance the selectivity and efficiency of photodynamic therapy (PDT) was the conjugation of the photosensitizer meta-tetrahydroxyphenylchlorin (mTHPC) to the water-soluble polymer polyethylene glycol (PEG). Several studies have demonstrated that mTHPC-PEG has a higher selectivity and a longer circulating half-life than free mTHPC, whereas no in vivo effect of this benefit could be seen.

STUDY DESIGN/MATERIALS AND METHODS

In a model of RAG-2-mice bearing a human oral squamous cell carcinoma xenograft (XF 354), the in vivo efficiency assessed as growth retardation or remission caused by Photofrin II and free mTHPC was compared with mTHPC coupled in two different ways to polyethylene glycol (PEG). One hundred and fourty-nine female RAG-2-mice were randomised into one control group and 13 therapy groups. Treatment parameters were adapted from those routinely applied in animal studies.

RESULTS

Photofrin II-mediated PDT and mTHPC-mediated PDT were both in vivo highly effective, whereas mTHPC induced less scars. The in vivo results after mTHPC-PEG-mediated PDT were disappointing, whereas the effectiveness of mTHPCnPEG-mediated PDT, a newly coupled macromolecular photosensitizer, were promising.

CONCLUSIONS

These results demonstrated the impact of the method of linkage between the photoactive agent mTHPC and polyethylene glycol (PEG) upon the in vivo effectiveness. mTHPC and mTHPCnPEG are promising photosensitizers for the future, especially for the cosmetic treatment needs of head and neck surgery.

Mode of action of methotrexate-albumin in a human T-cell leukemia line and activity against an MTX-resistant clone

Limitations of low mol. wt anticancer drugs are short tumor exposure times and toxicity to normal tissue. Methotrexate (MTX) covalently linked to human serum albumin (HSA) as a macromolecular carrier caused tumor regressions concomitant with a favorable toxicity profile in a clinical phase I trial (Hartung et aL, Clin. Cancer Res., 1999, 5, 753). We examined the uptake, intracellular degradation, metabolism and thymidylate synthase (TS) inhibition of MTX-HSA in the T-cell leukemia line CCRF-CEM and the MTX transport resistant clone CCRF-CEM/MTX. The number of MTX molecules per albumin molecule was determined by electrospray mass spectrometry. A loading ratio (LR) of approximately 1.4 mol MTX/albumin revealed intact complexes with one and two MTX molecules/albumin. In the complex with an LR of 5.7, albumin with up to 16 MTX molecules was seen. MTX-HSA was taken up by CCRF-CEM cells via endocytosis and cleaved by lysosomal enzymes. Liberated MTX was a poor substrate of folylpolyglutamate synthetase and was exported into the medium. TS was inhibited and cell survival was impaired by MTX-HSA in a time- and concentration-dependent manner. CCRF-CEM/MTX cells exhibited a growth inhibition of 30-40% after MTX-HSA treatment, but no TS inhibition. The alternative uptake route via endocytosis enables MTX-HSA to overcome transport resistance to MTX.

Pre-clinical evaluation of a methotrexate-albumin conjugate (MTX-HSA) in human tumor xenografts in vivo

Methotrexate covalently bound to human serum albumin in a 1:1 molar ratio (MTX-HSA) is a new macromolecular drug which is currently being studied in phase I clinical trials by the German Association for Medical Oncology (AIO) Phase I/II study group. Previous studies have shown that MTX-HSA differs favorably from unbound MTX in terms of plasma half-life time, tumor accumulation of albumin and uptake mechanisms into cancer cells. To achieve optimal drug efficacy, repeated treatment cycles were necessary. To evaluate the anti-tumor activity of MTX-HSA and MTX in pre-clinical in vivo models, we selected 7 solid human tumor xenografts growing s.c. in nude mice and administered drug either i.p. or i.v. weekly for 3 weeks. The maximal tolerated dose (MTD) of MTX-HSA in nude mice was 12.5 mg/kg given i.p. on days 1, 8 and 15, whereas the MTD for free MTX was 100 mg/kg given i.v. MTX-HSA was significantly more active (p > 0.01) than MTX in 3 models. In the soft tissue sarcoma SXF 1301, MTX-HSA effected complete remission/cure after a single injection, whereas free MTX resulted in short-lasting, partial tumor regression. In the prostate-cancer model PRXF PC3M, MTX-HSA produced growth inhibition of 92.8% of control or an optimal test/control (T/C) of 7.2% compared to a T/C of 20.8% for MTX (p = 0.05). In the osteosarcoma model SXF 1410, optimal T/C values were 10.2% and 14.5%, respectively (p = 0.025). In lung cancers LXFE 409 and LXFL 529, bladder cancer BXF 1258 and breast cancer MAXF 449, both compounds were inactive. The improved therapeutic effects seen in 3 xenograft models under MTX-HSA treatment are promising and might be due to specific accumulation of the compound in solid tumors owing to their enhanced permeability and retention effect. Thus, clinical development of MTX-HSA will continue and sarcomas as well as prostate cancers will be included as potential target tumors for upcoming clinical phase II trials.

Evidence for an instability near twice the fermi wave vector in the low electronic density liquid metal Li(NH3)4

We report high-resolution inelastic x-ray scattering measurements in the metallic liquid Li(NH3)4, which to a good approximation can be treated as a dilute alkali metal. We see a well-defined excitation out to large momentum transfers. This excitation shows a strong softening at wave vectors near the first peak in the structure factor, which occurs near twice the Fermi momentum.

Laser-induced fluorescence detection of malignant gliomas using fluorescein-labeled serum albumin: experimental and preliminary clinical results

To delineate the tumor margins of malignant gliomas laser-induced fluorescence detection technique was applied using 5-aminofluorescein-albumin as the fluorescent dye. The 5-aminofluorescein was linked to serum albumin (= AFlc-SA) as a cumulative protein label using residualizing markers. In a C6-glioma model the biodistribution and pharmacokinetics of the injected dye were investigated by labeling the protein conjugate with 111In-DTPA. Twenty-four hours after intravenous injection of the dye, fluorescence was activated by an argon laser and inspected in the C6-gliomas. Histological examinations were performed to compare the microscopic margins of the fluorescence-stained tumors with hematoxylin/eosin. The tumor uptake 24 h after dye injection was 23-fold higher than in the surrounding brain. Fluorescence inspection under laser activation demonstrated clearly stained and sharply demarcated tumors. The microscopic borders of the tumors corresponded exactly with the fluorescence, also demonstrating intracellular tumor uptake of the dye. In a preliminary study, three patients with malignant gliomas were operated using laser-induced fluorescence detection technique after injection of AFlc-SA. In all patients, the borders of the malignant gliomas were clearly stained by AFlc-SA during surgery. Laser-induced fluorescence imaging using the albumin conjugate AFlc-SA may be a promising method for delineating tumor margins which are hard to detect under the operating microscope alone.

Albumin-based drug carriers: comparison between serum albumins of different species on pharmacokinetics and tumor uptake of the conjugate

Albumin-based drug carrier systems have been developed in the field of chemotherapy to improve the passive tumor targeting properties of anti-cancer drugs. Usually, serum albumins of different species are used as carrier proteins, mostly of bovine (BSA), human (HSA) or rat (RSA) origin. The resulting albumin conjugates are often tested for anticancer activity in heterologous tumor models. No data is available whether the choice of the albumin species might influence the pharmacokinetics or the tumor uptake rates of the conjugates in vivo. Residualizingly ([111In]DTPA) radiolabeled RSA, BSA or HSA were administered to Walker-256 carcinoma-bearing rats. No significant difference was found in the absolute or the weight-adjusted tumor uptake rates of the three albumin tracers. The tumors were the major catabolic sites accumulating 14-18% of the injected dose (ID). Low hepatic uptake rates were determined for all albumins (below 100% ID). Minor differences were found for hepatic uptake in favor of the autologous RSA (5.8% ID) versus HSA (6.9%) and BSA (8.0%). These differences might have occurred during the commercial preparation or the radiolabeling of the different batches. In addition, there are structural differences between the three albumins, which might have contributed, despite high sequence homologies above 70% for RSA, HSA and BSA. These minor differences in the distribution patterns of RSA, HSA or BSA might not decisively influence the results of drug targeting experiments in rats. For further studies with albumin conjugates, HSA was chosen as drug carrier in rodent animal models when considering later human use. In rats or nude mice multiple injections of various HSA-drug conjugates were well tolerated without signs of allergy or anaphylaxis.

Phase I trial of methotrexate-albumin in a weekly intravenous bolus regimen in cancer patients. Phase I Study Group of the Association for Medical Oncology of the German Cancer Society

Methotrexate-albumin conjugate (MTX-HSA) is a novel human albumin-based prodrug conjugate of methotrexate (MTX). A low MTX loading rate provided optimal tumor targeting and therapeutic efficacy during preclinical testing. The objectives of this first Phase I study of MTX-HSA were to determine dose-limiting toxicity (DLT) and maximum tolerated dose (MTD) in a weekly regimen. Seventeen cancer patients who were no longer amenable to standard treatment were enrolled and were evaluable for DLT. Up to eight injections were performed in weekly intervals. Dose escalation was as follows: 20, 40, 50, and then 60 mg/m2 MTX-HSA (based on the amount of MTX bound to albumin). Additional MTX-HSA courses were feasible in case of tumor response. DLT (mainly stomatitis, Common Toxicity Criteria grade 3) occurred, beginning at the 50 mg/m2 dose level after repeated administrations; in one case, thrombocytopenia was dose-limiting. Two events of DLT occurred at the 60 mg/m2 dose level within the first two administrations. Mild anemia, transaminitis, and one case of skin toxicity were found. No significant leukopenia, nausea, renal toxicity, or other toxicities were observed. MTX-HSA was well tolerated. Drug accumulation occurred on the weekly schedule. The half-life of the drug was estimated to be up to 3 weeks. Tumor responses were seen in three patients: (a) a partial response was seen in one patient with renal cell carcinoma (response duration, 30 months, ongoing); (b) a minor response was seen in one patient with pleural mesothelioma (response duration, 31 months, ongoing); and (c) a minor response was seen in one patient with renal cell carcinoma (response duration, 14 months until progression). Poststudy treatment was administered at 2-4-week intervals. No signs of toxicity or drug accumulation were seen. Altered pharmacological properties of MTX-HSA such as plasma half-life, tumor targeting, or intracellular metabolism might have contributed to these responses. The MTD for weekly administration was 4 x 50 mg/m2 MTX-HSA during short-term treatment. A regimen with MTX-HSA injections of 50 mg/m2 every 2 weeks was recommended for a further clinical Phase I study.

Methotrexate-albumin conjugate causes tumor growth delay in Dunning R3327 HI prostate cancer-bearing rats

Based on the rationale of a preferred albumin uptake by tumors, conjugates comprising of rat serum albumin (RSA) as a drug carrier and of methotrexate (MTX) as chemotherapeutic drug were prepared. For a comparative study of MTX-RSA and MTX we chose a slow growing Dunning R3327 HI prostate cancer model. In a radiopharmacologic study blood kinetics and the tumor and organ distribution pattern of residualizingly labeled MTX-RSA were determined, and were found to be similar to that of residualizingly labeled RSA. The MTD was established for Copenhagen rats at a total four injections of 2 mg/kg MTX or MTX-RSA administered at days 0, 4, 8 and 12. Tumor volume measurements and tumor removal showed a small non-significant growth delay in the MTX treatment group, suggesting MTX resistance for the Dunning R3327 HI prostate carcinoma. In contrast, treatment with MTX-RSA resulted in a significant (50%) growth inhibition of the Dunning R3327 HI tumor. The cellular mechanisms responsible for MTX resistance in Dunning HI tumor cells is not known. The improved therapeutic effects seen during MTX-RSA treatment in this slow growing adenocarcinoma might be a result of prolonged tumor exposure time and an altered cellular uptake by a lysosomal route. MTX-albumin conjugates have shown antitumor activity exceeding that of MTX in several tumor xenografts in nude mice, including human prostate cancer. The recently initiated clinical development of MTX-human serum albumin will be continued and cancer of the prostate will be included as a potential target tumor during further clinical phase II testing.

Antitumor activity of methotrexate-albumin conjugates in rats bearing a Walker-256 carcinoma

We have recently reported that albumin accumulates in solid tumors and serves there as a source of nitrogen and energy. Methotrexate-albumin conjugates [MTX(I)-RSA] derivatized at a molar ratio of 1:1 differ favorably from original MTX in terms of plasma presence and tumor uptake. The purpose of this study was to evaluate the therapeutic efficacy of these novel conjugates in a comparative study with low m.w. MTX is Sprague-Dawley rats bearing a Walker-256 carcinoma. The maximum tolerated dose (MTD) for MTX and MTX(I)-RSA was determined (2 mg/kg based on MTX injected on days 1, 3 and 8). The tumor-bearing rats received injections of either the MTD or MTD/2 of MTX, MTX-albumin or mixtures containing the MTD/2 or MTD/4 of both MTX and MTX-albumin. No toxic side effects were observed. Cure rate and tumor growth retardation were slightly better for the conjugate compared with MTX alone in the MTD group (16 complete remissions vs. 14 of 20 rats). The best results were achieved for the combination treatment with MTX and MTX-albumin, with complete remission in all 20 rats. In conclusion, MTX-albumin conjugates show therapeutic activity in vivo without toxic side effects. Additive effects were observed for a combination of MTX-albumin and MTX. These effects might be caused by the much longer tumor exposition time of the conjugate in conjunction with a different route of uptake (pinocytosis for MTX-albumin vs. folate receptors for MTX).

Pharmacokinetics of methotrexate-albumin conjugates in tumor-bearing rats

Linking chemotherapeutic drugs to a macromolecular carrier system may enhance tumor targeting, reduce toxicity and overcome drug resistance mechanisms. As an elementary model to evaluate the pharmacological properties of macromolecular drug carrier systems we chose rat serum albumin (RSA) for carrier and methotrexate (MTX) as antineoplastic drug. The conjugation procedure yielded conjugates with an approximate 1:1 molar loading rate (MTX(1)-RSA). In the first part of the study a residualizing [111In]DTPA protein label was used for mapping in vivo the catabolic sites of the native carrier protein and of the MTX(1)-RSA drug conjugate in Walker 256 carcinosarcoma bearing rats. The tumor accumulation was about 14% of the injected dose for the RSA and MTX(1)-RSA tracers after 24 h. Tracer entrapment by organs with an active mononuclear phagocyte system was low (liver below 7% and spleen below 1.5% of the injected dose after 24 h). The 1:1 conjugation of MTX to RSA did not decisively alter the pharmacokinetic properties nor the tumor or tissue distribution of the native carrier protein RSA. In the second part of the study the different properties of the MTX(1)-RSA conjugate were compared with MTX in vivo. About 2 mg MTX/kg body weight either of the drug conjugate or of the original drug were injected after being additionally spiked with radiolabeled tracers. Plasma concentrations were simultaneously determined by immunological and radioactive means. After 24 h about 12% MTX(1)-RSA was found in circulation compared to 0.03% MTX. Favorable tumor accumulation rates of about 14% were achieved for MTX(1)-RSA versus 0.04% for MTX. About 45-fold more of the injected dose of [3H]MTX accumulated in the liver as compared to the tumor (1.5 versus 0.03%) after 24 h. Conjugation of MTX to RSA reversed this ratio in favor of the tumor to 1:1.4 (13.6 versus 9.6%). In conclusion, the potential therapeutic benefit of the MTX(1)-RSA conjugate lies in its very long tumor exposure time and its improved tumor accumulation rate compared to conventional MTX. In addition the conjugation to albumin might enhance the therapeutic effects over those achieved by long-term continuous infusion of MTX, as MTX(1)-RSA enters the cells by a different uptake mechanism. This might also help to circumvent MTX resistance mechanisms, such as a reduction in folate receptor numbers or impaired MTX polyglutamylation.