PARTICLE COMPRISING LANTHANIDE HYDROXIDE

Abstract

The disclosure is directed to a spherical particle comprising lanthanide hydroxide, a method of preparing the particle, the particle for use in medical applications, a suspension, a composition, a method of obtaining a scanning image, and the particle for use in the treatment of a subject.

Claims

1. A spherical particle comprising lanthanide hydroxide.

2. The spherical particle according to claim 1, comprising an amount of lanthanide of 15-90% by total weight of the particle.

3. The spherical particle according to claim 1, having an atomic oxygen content of 5-90%, based on a total weight of the particle.

4. The spherical particle according to claim 1, comprising one or more metals selected from the group consisting of scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium.

5. The spherical particle according to claim 1, further comprising one or more metal complexes, wherein the one or more metal complexes comprise one or more Lewis bases.

6. The spherical particle according to claim 5, wherein the one or more Lewis bases are selected from the group consisting of monodentate ligands and chelating ligands.

7. The spherical particle according to claim 6, wherein the monodentate ligands and/or chelating ligands are selected from the group consisting of hydride, oxide, hydroxide, water, acetate, sulphate, carbonate, phosphate, ethylene diamine, oxalate, dimethyl glyoximate, methyl acetoacetate, and ethyl acetoacetate.

8. The spherical particle according to claim 1 having an average particle diameter in a range of 5 nm to 400 μm.

9. The spherical particle according to claim 1, having a sphericity of at least 0.85.

10. The spherical particle according to claim 1 being radioactive.

11. A method of preparing the spherical particle according to claim 1, comprising: i) adding at least one metal particle to a salt solution to form a mixture; ii) stirring the mixture to form the particle; iii) recovering from at least part of the mixture of ii) the particle.

12. The method according to claim 11, further comprising a heat treatment step, resulting in formation of the particle comprising lanthanide oxide.

13. The spherical particle according to claim 1 which is a particle in medical applications.

14. A suspension comprising the spherical particle according to claim 1 wherein the suspension is at least one selected from the group consisting of a therapeutic suspension, a diagnostic suspension, and a scanning suspension.

15. (canceled)

16. (canceled)

17. The suspension according to claim 14, wherein the scanning suspension is a magnetic resonance imaging scanning suspension or a nuclear scanning suspension.

18. (canceled)

19. A composition comprising the particle according to claim 1, wherein the particle further comprises a pharmaceutically acceptable carrier, diluent and/or excipient.

20. A composition comprising a suspension according to claim 14, wherein the particle present in the suspension further comprises a pharmaceutically acceptable carrier, diluent and/or excipient.

21. A method of obtaining a scanning image, comprising: i) administering to a human, humanoid, or nonhuman the suspension according to claim 14, and subsequently ii) generating a scanning image of the human, humanoid, or nonhuman.

22. The method of claim 21, wherein the scanning image is a tomographic image.

23. A method for treating a subject comprising: i) administering to the subject a diagnostic composition or scanning composition, comprising the particle according to claim 1, wherein the particle is capable of at least in part disturbing a magnetic field; ii) obtaining a scanning image of the subject; iii) determining a distribution of the particle within the subject; iv) administering to the subject a therapeutic composition comprising the particle.

24. A method for treating a subject comprising: i) administering to the subject a diagnostic composition or scanning composition, comprising the particle according to claim 12, wherein the particle is capable of at least in part disturbing a magnetic field; ii) obtaining a scanning image of the subject; iii) determining a distribution of the particle within the subject; iv) administering to the subject a therapeutic composition comprising the particle.

25. The method according to claim 23, wherein the particle in the therapeutic composition has a higher amount of activity per particle than the particle in the diagnostic composition or scanning composition.

26. The spherical particle according to claim 1 capable of at least in part disturbing a magnetic field in a treatment of a tumour in a subject, wherein a dosage of the particle is derived from a scanning image obtained with a scanning suspension comprising particles capable of at least in part disturbing a magnetic field with the same chemical structure as the particle, based on a distribution of the particles of the scanning suspension with the same chemical structure within the subject.

27. The spherical particle according to claim 26, wherein the scanning image is obtained with tomographic imaging.

28. The spherical particle according to claim 26, wherein the scanning suspension is a therapeutic suspension comprising a spherical particle comprising lanthanide hydroxide.

29. The spherical particle according to claim 26, wherein the particle exhibits a higher amount of radioactivity per particle than the particles used for obtaining the scanning image.

30. (canceled)

31. The method of claim 22, wherein the tomographic image is generated with at least one selected from the group consisting of CLI, CT, dual energy CT, MRI, PET and SPECT.

32. The method of claim 22, wherein the tomographic image is generated with dual energy CT.

33. The spherical particle according to claim 27, wherein the scanning image is obtained with tomographic imaging generated with at least one selected from the group consisting of CLI, CT, dual energy CT, MRI, PET and SPECT.

34. The spherical particle according to claim 33, wherein the scanning image is obtained with tomographic imaging generated with dual energy CT.

Description

EXAMPLES

Materials

[0163] All chemicals are commercially available and were used as obtained. Holmium chloride (HoCl.sub.3.6H.sub.2O; M.sub.w=379.38 g/mol; 99.9%) was obtained from Metal Rare Earth Limited. Acetyl acetone (acac; ReagentPlus®; M.sub.w=100.12 g/mol; >99%), polyvinyl alcohol (PVA; M.sub.w=30 000-70 000 g/mol; 87-90% hydrolysed) were obtained from Sigma-Aldrich. Sodium hydroxide (pellets EMPLURA®, M.sub.w=40.00 g/mol), ammonium hydroxide (EMSURE®; M.sub.w=35.05 g/mol; 28-30%), chloroform (EMPROVE®, M.sub.w=119.4 g/mol), were supplied by Millipore.

Example 1

Preparation of Holmium Hydroxide Microspheres

[0164] The starting material to prepare holmium hydroxide microspheres was holmium acetyl acetonate microspheres (FIGS. 1 and 2). The preparation of holmium acetyl acetonate was reported by Arranja, et al., Int. J. Pharm. 2018, 548, 73-81. A solution of crystals of holmium acetyl acetonate (10 g) dissolved in chloroform (186 g) was added to an aqueous solution of polyvinyl alcohol (1 kg water with 2% w/w polyvinyl alcohol). Overhead four blades propeller stirrers (Hei-TORQUE Value 100, Heidolph, Germany) were used to vigorously stir the mixture at 300 rpm in two litres baffled beakers to obtain an oil-in-water (o/w) emulsion. After 48 hours, the microspheres were sieved according to the desired size (20-50 μm) using an electronic sieve vibrator (TOPAS EMS 755). The sieved microspheres were dried at room temperature for 5 hours under ambient pressure, followed by vacuum drying at room temperature for 72 hours. Then, dried holmium acetyl acetonate microspheres (7 g) were added to an aqueous solution of 0.5 M sodium hydroxide (NaOH, 875 g H.sub.2O, pH 13.5) to form holmium hydroxide microspheres. The dispersion was prepared in two litres baffled beakers and continuously stirred at 500 rpm and room temperature for 2 hours using overhead four blades propeller stirrers (Hei-TORQUE Value 100, Heidolph, Germany). After stirring, the holmium hydroxide microspheres were formed and collected into four 50 ml tubes. The microspheres were washed four times with water by centrifugation. After washing, the microspheres were dried in a vacuum oven at room temperature for 24 hours.

Characterisation

[0165] The size distributions of the starting material (holmium acetyl acetonate microspheres) and the final microspheres (holmium hydroxide microspheres; Table 1 and FIG. 4A) were determined using a Coulter counter equipped with an orifice of 100 μm (Multisizer 3, Beckman Coulter, Mijdrecht, The Netherlands). FIG. 4A further shows the determined size distribution of holmium phosphate microspheres.

[0166] An optical microscope (AE2000 Motic) was used to investigate the morphological properties of the microspheres suspended in water (sphericity and surface damages). The surface composition and smoothness of the microspheres was analysed using a Scanning Electron Microscope-Energy Dispersive X-ray Spectroscopy (SEM-EDS) (JEOL JSM-IT100, InTouchScope™, Tokyo, Japan; FIG. 2).

[0167] The zeta (ζ-)potential was determined using a Zetasizer Nano-Z Malvern Instruments) which was calibrated using a zeta potential transfer standard (DST1235, −42±4.2 mV, Malvern Instruments, UK). The samples were prepared by dispersing 25 mg of holmium phosphate microspheres or holmium hydroxide microspheres in 10 mM sodium chloride. FIG. 4B shows the comparative apparent ζ-potentials of holmium hydroxide microspheres and holmium phosphate microspheres. The pH values of the dispersions were measured (FiveEasy Plus, Mettler Toledo LE410) and were 7.0±0.2 (n=3 for each microsphere). Then, the samples were transferred into a dip cell (Universal Dip Cell Kit, ZEN 1002, Malvern Instruments, UK) and the temperature in the cell was stabilized at 25° C. for 90 seconds after which the electrophoretic mobility was determined. The ζ-potential was calculated using the Helmholtz-Smoluchowski equation (FIG. 4B). The mean zeta potential of the holmium phosphate was −27.1±2.3 mV and of the holmium hydroxide was −0.6±2.0 mV in 10 mM NaCl.

[0168] The zeta potential of the holmium phosphate and holmium hydroxide microspheres was also determined using a ZetaCompact (CAD instruments, France). The samples were prepared by dispersing approximately 50 mg of microspheres in 10 ml of water for injection (BBraun, Germany). The pHs of the dispersions were measured (FiveEasy Plus, Mettler Toledo LE410) and were 7.3±0.2 for the holmium phosphate and 7.0±0.1 for the holmium hydroxide (n=3 for each microsphere type). The samples were transferred into a quartz capillary cell and the electrophoretic mobility of individual microspheres was recorded by video microscopy. The zeta potential was then obtained using the Smoluchowski formula. The zeta potential of 500-1000 microspheres of holmium phosphate and of holmium hydroxide was obtained (FIG. 5). The mean zeta potential of the holmium phosphate was −23.8±8.9 mV and of the holmium hydroxide was −17.9±5.2 mV in water.

[0169] The density of the holmium hydroxide microspheres was determined in water using a 25 cm.sup.3 specific gravity bottle (Blaubrand NS10/19, DIN ISO 3507, Wertheim, Germany; FIG. 3) and using a sample amount of approximately 250 mg (FIG. 3).

[0170] The holmium content was determined by Inductively Coupled Plasma-Optical Emission spectroscopy (ICP-OES; FIG. 6). Before preparation of the sample for ICP-OES analysis, the microspheres were dried overnight in a vacuum oven at room temperature. Then, samples of 20 to 50 mg were dissolved in 50 ml of 2% nitric acid and the holmium concentration of the solutions was measured at three different wavelengths (339.9, 345.6 and 347.4 nm) using an Optima 4300 CV (PerkinElmer, Norwalk, USA).

[0171] The holmium content was also determined by Atomic Absorption Spectroscopy (Perkin Elmer Model AAnalyst 200) and the carbon and hydrogen contents determined with a CHNS analyzer (Elementar Model Vario Micro Cube). These elemental determinations (FIG. 6) of the holmium, carbon and hydrogen contents were performed in duplicate by Mikroanalytisches Laboratorium KOLBE (Oberhausen, Germany) and the samples were dried overnight in a vacuum oven at 100° C. The oxygen content cannot be determined accurately due to interference from the high amount of holmium, and was assumed to be the remaining component of the microspheres as no other element is expected to be present in the microspheres [% oxygen=100−(% carbon+% hydrogen+% holmium)].

[0172] X-ray powder diffraction (XRD) patterns of the holmium hydroxide microspheres were obtained by depositing a small amount (about 5 mg) of each sample on a Si-510 wafer and analysed using a Bruker D8 Advance diffractometer in Bragg-Brentano geometry with a Lynxeye position sensitive detector (FIG. 7B). FIG. 7 further shows a comparison with the X-ray powder diffraction pattern of holmium phosphate microspheres (A).

[0173] Fourier Transform Infrared (FTIR) spectrum of the holmium hydroxide microspheres was obtained using a Nicolet 8700 FTIR spectrometer (Thermo Electron Corporation) equipped with a KBr/DLa/TGS D301 detector cooled with liquid nitrogen (FIG. 8A). FIG. 8A further shows as a comparison the FTIR spectra of holmium oxide and holmium phosphate microspheres. A small amount of the sample (5-10 mg) was pressed onto potassium bromide salt and the sample holder was stabilised for 5 minutes at 25° C. and kept at this temperature during the analysis. The FTIR spectra of the microspheres were collected at a resolution of 4 cm.sup.−1 averaged over 128 scans.

[0174] Thermogravimetric analysis (TGA) of the microspheres was performed using a TGA2 Star System (Mettler Toledo; FIG. 8B). FIG. 8B further shows the TGA of holmium phosphate microspheres. Samples of 12-15 mg of microspheres were heated from 30° C. up to 800° C. in a nitrogen environment at a heating speed of 5° C./min and the weight loss was recorded. After the heat treatment, the resulting powders were also analysed by FTIR using the same conditions as described above and are shown in FIG. 8A.

Neutron Activation

[0175] The holmium hydroxide microspheres were neutron activated in the pneumatic rabbit system (PRS) facility of the nuclear reactor research facility operational at the Department of Radiation Science and Technology of the Delft University of Technology (The Netherlands). This facility has an average neutron thermal flux of 4.72×10.sup.16 m.sup.−2.Math.s.sup.−1, s epithermal neutron flux of 7.87×10.sup.14 m.sup.−2.Math.s.sup.−1 and a fast neutrons flux of 3.27×10.sup.15 m.sup.−2.Math.s.sup.−1. Several amounts of microspheres (from 251 to 292 mg) were sealed in polyethylene vials which were placed into polyethylene rabbits for irradiation (Vente et al., Biomed. Microdevices 2009, 11, 763-772; Vente et al., Eur. J. Radiol. 2010, 20, 862-869). The microspheres were irradiated for 2, 4 and 6 hours (n=2) to yield radioactive holmium-166 hydroxide microspheres (.sup.166Ho(OH).sub.3-ms); FIGS. 9 and 10). Both FIGS. 9 and 10 show, as a comparison, the data of holmium phosphate microspheres as well. During neutron bombardment, the microspheres also received a γ-dose of approximately 298 to 312 kGy per hour of irradiation. The maximum temperature reached during irradiation was monitored with temperature indicator strips (temperature points: 37° C., 40° C., 43° C., 46° C., 49° C., 54° C., 60° C., and 65° C.) that were attached to the vials immediately prior to irradiation (Digi-Sense, Cole-Parmer). The conditions of all the neutron bombardments preformed in this study are shown in FIG. 10 (this includes data from holmium phosphate microspheres).

[0176] After neutron activation, the activity of the samples at a specific time (A.sub.t) was measured using a dose calibrator (VDC-404, Comecer, The Netherlands). This measurement enables the calculation of the actual activity at the end of neutron activation (i.e. end of bombardment (EoB) (A.sub.EoB)) by taking into account the radioactive decay after neutron activation and the measurement time, according to the following equations;

A.sub.t=A.sub.EoB.Math.e.sup.−λt  (1)

[00003]$\left(2\right)\lambda =\frac{\ln 2}{T_{1/2}},$

λ=decay constant (s.sup.−1) and T.sub.1/2=half-life of the radionuclide.

[0177] The activity of the holmium hydroxide was measured when these samples decayed to 200-500 MBq/sample.

Radiochemical Purity after Neutron Activation

[0178] The holmium hydroxide microspheres that were neutron irradiated for 6 hours were analysed by gamma spectrometry after 24 and 28 days of decay time to determine the presence of radionuclide impurities, especially the longer lived radionuclides. A LG22 High Purity Germanium (HPGe) detector from Gamma Tech (Princeton, USA) and a gamma spectrum analysis software (Genie™ 2000 Ver. 3.2, Canberra, Meriden, USA) were used. Each sample was counted for 120 seconds at a defined distance from the detector. The radioactive elements that corresponded to significant energy peaks were identified.

Stability of Microspheres in Administration Fluids after Neutron Activation

[0179] After neutron activation, the holmium hydroxide microspheres were decayed for 21 days before handling to minimise radiation exposure. Then, the holmium hydroxide microspheres were incubated with 0.9% sodium chloride (2 ml per sample) and vortexed for 10 minutes. Subsequently, the morphological properties of the microspheres were observed by optical microscopy and the size distribution was measured at predetermined time points (1, 24, 48 and 72 hours; FIG. 11). FIG. 12 shows optical microphotographs of 4 and 6 hours neutron irradiated holmium phosphate microspheres as well. Samples of the supernatant (200 μl) were collected at the same time points, diluted in 5 ml of 2% nitric acid and analysed by ICP-OES to detect possible holmium leakage (FIG. 11).

Haemocompatibility, Haemolysis and Coagulation

[0180] One of the requirements of microspheres that will directly contact blood in certain applications, such as radiation segmentectomy or radioembolisation, is that they are haemocompatible.

[0181] The holmium phosphate and holmium hydroxide microspheres were incubated with full human blood (concentrations ranging from 5 to 40 mg/ml), followed by analysis of the haemogram after 4 hours and 24 hours using an automated blood cell analyser (CELL-DYN Sapphire, Abbott Diagnostics, Santa Clara, Calif., USA) (FIG. 13). Statistical analysis of the haemogram results (red blood cell count, red cell distribution width, mean corpuscular volume, mean corpuscular haemoglobin concentration, haematocrit and white blood cell viability) revealed no statistically significant difference between the blood incubated with the microspheres and the respective controls (p>0.05). The holmium phosphate and holmium hydroxide microspheres did not induce alterations of the blood parameters as well as no statistically significant cytotoxicity was observed towards the white blood cells (FIG. 13).

[0182] The haemolysis potential of the holmium phosphate and holmium hydroxide microspheres was determined according to the ASTM F756-00 and ASTM E2524-08. The microspheres were incubated at 37° C. with gentle mixing (VWR® mutating mixer) for 3 hours with diluted human heparinised blood at final concentrations of 0.04 mg/ml, 0.2 mg/ml, 1 mg/ml and 10 mg/ml. After incubation, the samples were centrifuged (800×g, 15 min), and the concentration of haemoglobin in a supernatant was determined. The results expressed as a percentage of haemolysis (FIG. 14) were used to evaluate the acute in vitro haemolytic properties of the microspheres. A sample with a percentage of haemolysis less than 2% is considered not haemolytic, a percentage of haemolysis between 2-5% is considered slightly haemolytic, and a result of more than 5% means the sample is haemolytic according to ASTM F756-00. FIG. 14 demonstrates that the holmium phosphate and holmium hydroxide microspheres are not haemolytic in the tested concentration range (0.04 to 10 mg/ml).

[0183] The ability of the holmium phosphate and holmium hydroxide to interact with the plasma coagulation factors of the intrinsic pathway was assessed using the activated prothrombrin time (aPTT) test. This assay evaluates the functionality of some coagulation factors (e.g., XII, XI, IX, VIII, X, V, and II). An increase of the coagulation time suggests that the material depletes or inhibits these coagulation factors. Therefore, a plasma coagulation time longer than the normal value for the aPTT test (i.e., more than 34.1 s) is considered abnormal. The holmium phosphate and holmium hydroxide microspheres were incubated with human plasma and the coagulation times after incubation with the aPTT reagent were measured. FIG. 15 shows that neither the holmium phosphate nor holmium hydroxide microspheres deplete or inhibit the coagulation factors of the intrinsic pathway in the tested concentration range (0.04 to 10 mg/ml).

Example 2

[0184] Microspheres composed of lanthanides other than holmium, such as dysprosium and yttrium, were also prepared. The morphological properties, smoothness and surface composition of the microspheres were analysed using a Scanning Electron Microscope-Energy Dispersive X-ray Spectroscopy (SEM-EDS) (JEOL JSM-IT100, InTouchScope™, Tokyo, Japan).

[0185] FIG. 16 depicts dysprosium hydroxide microspheres, and the respective surface elemental analysis by SEM-EDS. FIG. 17 shows a scanning electron microphotograph of the prepared yttrium hydroxide microspheres, and the corresponding surface elemental analysis by SEM-EDS.

Example 3

[0186] The imaging and quantification of radioactive holmium phosphate microspheres and holmium hydroxide microspheres were performed by preparing phantoms of phytagel, containing increasing concentrations of radioactive microspheres. Homogeneous distributed microspheres as well as sedimented microspheres were prepared and imaged using CT (FIG. 18), SPECT (FIG. 19) and CLI (FIG. 20). SPECT scans were acquired in a Symbia Truepoint (Siemens) and the data was processed with IRW (Inveon Research Workplace, Siemens), which resulted in good dose quantification. CLI was performed in an In Vivo Imaging System (IVIS Lumina, PerkinElmer).