SIZE CONTROLLED RADIOLABELLED PARTICLES
20230372554 · 2023-11-23
Inventors
Cpc classification
A61K51/0489
HUMAN NECESSITIES
International classification
Abstract
The present disclosure relates to a particle comprising a degradable compound, a radionuclide, and a phosphorus containing additive. Phosphorus containing additives, such as phosphonates, have the unique ability to control the size of particles for medical applications. The applications allow for use of the particles as medicaments and for imaging, especially within the field of cancer.
Claims
1. A particle comprising a degradable compound, a radionuclide, and a phosphorus containing additive wherein, said degradable compound comprises CaCO.sub.3 and said phosphorus containing additive is selected from the group consisting of orthophosphates, linear oligophosphates, linear polyphosphates, cyclic polyphosphates, phosphonates, bisphosphonates and polyphosphonates.
2-21. (canceled)
22. The particle according to claim 1, wherein the phosphorus containing additive is sodium hexametaphosphate (SHMP), EDTMP-ethylenediamine tetra(methylene phosphonic acid) and/or Pamidronate.
23. The particle according to claim 1, wherein the phosphorus containing additive is EDTMP-ethylenediamine tetra(methylene phosphonic acid).
24. The particle according to claim 1, wherein the radionuclide is selected from the group consisting of .sup.225Ra, .sup.224Ra, .sup.223Ra, .sup.225Ac, .sup.212Bi, .sup.227Th, .sup.211At, .sup.213Bi, .sup.212Pb, .sup.64Cu, .sup.67Cu, .sup.166Ho, .sup.177Lu, .sup.32P, .sup.186Re, .sup.188Re, .sup.153Sm, .sup.89Sr, .sup.161Tb, .sup.90Y, .sup.220Rn, .sup.216Po, .sup.212Po, .sup.208Tl, .sup.18F, .sup.67Ga, .sup.86Y, .sup.99mTc, .sup.111In, .sup.203Pb, .sup.83Sr, .sup.152Tb and .sup.155Tb.
25. The particle according to claim 1, wherein the radionuclide is a beta emitter with alpha-progenies suitable for therapy which is .sup.212Pb with progeny radionuclides .sup.212Bi, .sup.212Po and .sup.208Tl.
26. The particle according to claim 1, wherein the radionuclide is selected from the group consisting of alpha-emitting .sup.224Ra with the progeny radionuclides .sup.220Rn, .sup.216Po, .sup.212Pb, .sup.212Bi, .sup.212Po and .sup.208Tl.
27. The particle according to claim 1, wherein the radionuclide is .sup.224Ra, and the phosphorus containing additive is EDTMP-ethylenediamine tetra(methylene phosphonic acid).
28. The particle according to claim 1, wherein the radionuclide is .sup.212Pb, and the phosphorus containing additive is Pamidronate.
29. The particle according to claim 1, wherein the size of the particle is from 1 nm to 500 μm.
30. A composition comprising one or more particles according to claim 1.
31. A composition, according to claim 30, which is a pharmaceutical composition further comprising a diluent, carrier, surfactant, and/or excipient.
32. The composition according to claim 30, wherein the phosphorus containing additive is associated with the particle by being present in the composition or suspension, by being part of the particle, being on the surface of the particle, being in the dispersion of the particle, being part of the composition or suspension and/or dispersion of particles, or being part of the particle and as part of the composition or suspension of particles.
33. The composition according to claim 30, prepared with an amount of radionuclide that is 1 kBq to 10 GBq per dosing or with an amount of radionuclide that is 50 MBq to 100 GBq suitable for multidose industrial scale production.
34. The composition according to claim 30, wherein the composition is a particle suspension comprising monodisperse or polydisperse particles which comprise a degradable compound, a radionuclide, and a phosphorus containing additive wherein, said degradable compound comprises CaCO.sub.3 and said phosphorus containing additive is selected from the group consisting of orthophosphates, linear oligophosphates, linear and polyphosphates, cyclic polyphosphates, phosphonates, bisphosphonates and polyphosphonates.
35. The composition according to claim 30, which is suitable for parenteral use or intratumor injection.
36. A method of inhibiting a cancer comprising administering the particle of claim 1 to a subject that has a cancer, wherein the cancer is selected from the group consisting of intraperitoneal cancers, intracranial cancers, pleural cancers, bladder cancers, cardiac cancers, cancers in the subarachnoid cavity, and non-cavitary cancers.
37. The method of claim 36, further comprising administering to said subject a chemotherapy, a DNA repair inhibitor or a radioimmunotherapy.
38. The method of claim 36, wherein the concentrations of phosphonates and or phosphate compounds are 1 microgram to 1000 milligram per ml particles in the final solution.
39. A method for preparing a particle according to claim 1, the method comprising bringing a degradable compound, a radionuclide, and a phosphorus containing additive in contact with each other with or without using a carrier for the radionuclide.
40. A method for preparing a composition according claim 30, wherein a degradable compound and a radionuclide has formed a particle in an initial step, which subsequently is coated with the phosphorus containing additive or has the with the phosphorus containing additive at least partly associated with the particle.
Description
BRIEF DESCRIPTION OF THE FIGURES
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EXAMPLES
Example 1—Preparation of Microparticles
[0170] Crystalline CaCO.sub.3 microparticles subsequently used for surface labeling with .sup.224Ra were prepared by a spontaneous precipitation method based on the protocol described by Volodkin et al. 2004. Equal volumes of 0.33 M Na.sub.2CO.sub.3 (Merck, Darmstadt, Germany) and 0.33 M CaCl.sub.2) (Merck) was vigorously mixed with an overhead stirrer (Eurostar 20, IKA®-Werke GmbH & Co. KG, 120 Staufen, Germany) before the precipitated microparticles were collected by centrifugation. The precipitate was washed in ph.Eur water and dried in a heated vacuum oven. The microparticles had mainly spherical geometry, and the median diameter was 4 to 7 μm when measured by a laser diffraction particle size analyzer (Mastersizer 3000, Malvern Instruments Ltd, Worcestershire, UK).
[0171] Microparticles were also prepared by mixing of stock solutions of up to 1 M of Na.sub.2CO.sub.3 and CaCl.sub.2) with .sup.224Ra present to produce inclusion labeled microparticles as described further in Example 5. Example 5 also describe how in some applications; a layer of CaCO.sub.3 was precipitated on the surface of already labeled microparticles to make a thin encapsulation for surface protection.
Example 2—Use of Phosphorus Containing Additive for Size Control
[0172] Phosphorus containing compounds such as phosphonates and phosphates can be applied as additives to stabilize crystal particles. They can be added to crystal particles during the formation of these, after the crystal particles have been formed, after labeling or to the final formulation in order to achieve the size control. The product can be sterilized by autoclaving and the additives can be included before or after this process. The size controlling additive can also be used as a component of a kit used to prepare a final product.
[0173] Phosphonates and phosphonic acids are organophosphorus compounds containing C—PO(OH).sub.2 or C—PO(OR).sub.2 groups (where R=alkyl, aryl). Phosphonic acids, typically handled as salts, are generally non-volatile solids that are poorly soluble in organic solvents, but soluble in water and common alcohols. Bisphosphonates include Etidronate (HEDP), Clodronate, Tiludronate, Pamidronate, Neridronate, Olpadronate, Alendronate, Ibandronate, Risedronate, Zoledronate. Polyphosphonates include EDTMP-ethylenediamine tetra(methylene phosphonic acid), DOTMP-1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetrayl-tetrakis(methylphosphonic acid) and DTPMP-diethylenetriaminepenta(methylene-phosphonic acid)
[0174] A phosphoric acid, in the general sense, is a phosphorus oxoacid in which each phosphorus atom is in the oxidation state +5, and is bonded to four oxygen atoms, one of them through a double bond, arranged as the corners of a tetrahedron. Removal of the hydrogen atoms as protons H+ turns a phosphoric acid into a phosphate anion. Partial removal yields various hydrogen phosphate anions. Phosphates include orthophosphate, linear oligophosphates and polyphosphates, such as pyrophosphate, tripolyphosphate and triphosphono phosphate, and cyclic polyphosphates such as sodium hexametaphosphate (SHMP).
Example 3—Production of .SUP.224.Ra and .SUP.212.Pb
[0175] The .sup.224Ra-generator was prepared by mixing a .sup.228Th source with an actinide resin and loading it on a column. A source of .sup.228Th in 1 M HNO.sub.3 was purchased from Eckert & Ziegler (Braunschweig, Germany) or Oak Ridge National Laboratory (TN, USA), and an actinide resin based on the DIPEX® Extractant was acquired from Eichrom Technologies LLC (Lisle, IL) in the form of a pre-packed cartridge of 2 mL. The material in an actinide resin cartridge was extracted and the resin was preconditioned with 1 M HCl (Sigma-Aldrich). A slurry of approximately 0.25 mL actinide resin, 0.25 mL 1 M HCl and 0.1 mL .sup.228Th in 1 M HNO.sub.3 was prepared in a vial (4 mL vial, E-C sample, Wheaton, Millville, NJ) and incubated with gentle agitation for immobilization of .sup.228Th for 4 h at room temperature and let to rest for a few days. The generator column was prepared in a 1 mL filtration column (Isolute SPE, Biotage AB, Uppsala, Sweden) by first applying 0.2 mL of inactive actinide resin, before the portion containing .sup.228Th was loaded on top. The inactive resin was introduced in the bottom of the column to serve as a catcher layer if .sup.228Th was released during operation of the generator. Later, the capacity of the generator was increased. A slurry consisting of 0.4 mL actinide resin, 0.5 mL .sup.228Th in 1 M HNO.sub.3 and 0.5 mL 1 M HCl was prepared as described above, before it was loaded onto the generator column.
[0176] Radium-224 could be eluted regularly from the generator column in 1-2 mL of 1 M HCl. For further purification, the crude eluate from the generator column was loaded directly onto a second actinide resin column. The second column was washed with 1 M HCl. This eluate was evaporated to dryness in a closed system. The vial was placed in a heater block and flushed with N2-gas through a Teflon tube inlet and outlet in the rubber/Teflon septum on the vial. The acid vapor was lead into a beaker of saturated NaOH by a stream of N2-gas. The radioactive residue remaining after evaporation was dissolved in 0.2 mL or more of 0.1 M HCl. A radioisotope calibrator (CRC-25R, Capintec Inc., Ramsey, NJ) was used to measure the total extracted activity in the process.
[0177] Lead-212 was produced from .sup.224Ra via .sup.220Rn emanation using a novel simplified single chamber diffusion system modified from the method of Hassfjell S., 2001. About 2-20 pL of a .sup.224RaCl.sub.2 solution (˜250 kBq), prepared as described above, was distributed on the surface of a small paper strip (15×5 mm) attached to a syringe tip that had previously been inserted through the silicone septum of a 3 mL micro reaction vessel glass v-vial (Supelco, Darmstadt, Germany) screw cap. The screw cap was carefully attached to the v-vial, avoiding contact between the paper strip and the v-vial interior surfaces. The sealed v-vial was left to rest overnight in a fume hood. Next, .sup.220Rn released through air inside the vial from the .sup.224Ra source, diffused and decayed into .sup.212Pb via its short-lived daughter .sup.216Po and was deposited inside the container. After 20 to 28 h, the cap with the paper strip was carefully removed, avoiding .sup.224Ra contamination of the vial. The .sup.212Pb was subsequently washed off from the glass walls with 1 M HCl and transferred to a new container.
Example 4—Methods of Measuring Radioactivity
[0178] Radioactive samples up to approximately 30 kBq were measured by an automated NaI gamma counter (Hidex, Turku, Finland) in the energy range from 60-110 keV for quantification of .sup.212Pb and 65-345 keV for .sup.224Ra. As seen in Table 1 the most abundant x- and y-radiation in these energy ranges is from .sup.212Pb. The counts in these windows are assumed to mainly originate from .sup.212Pb with minimal contribution from other nuclides in the series. Radium-224 activity was determined indirectly based on the counts in the 65-345 keV window. This was carried out by re-measuring the samples between 2-4 days after the first measurement, when the initial .sup.212Pb present in the sample had decayed and transient equilibrium had been established. A pure source of .sup.224Ra reaches equilibrium conditions after approximately 2 days based on the half-lives of .sup.224Ra and .sup.212Pb.
TABLE-US-00001 TABLE 1 Overview of x- and/or γ-lines in the .sup.224Ra-series with 1% or higher abundance. The X- and γ-lines are divided into two columns, one for energies between 65-345 keV and the second for energies above 345 keV. 60-110 keV >110 keV Radionuclide (Abundance, %) (Abundance, %) .sup.224Ra none 241.0 (4.1) .sup.220Rn none none .sup.216Po none none .sup.212Pb 74.8 (10.3) 238.6 (43.6) 77.1 (17.3) 300.1 (3.3) 86.8 (2.1) 87.4 (4.0) 89.8 (1.5) .sup.212Bi none 727.3 (6.7) 785.4 (1.1) 1620.5 (1.5) .sup.212Po none none .sup.208Tl 72.8 (2.0) 277.4 (6.6) 75.0 (3.4) 510.8 (22.6) 583.2 (85.0) 763.1 (1.8) 860.6 (12.5) 2614.5 (99.7)
[0179] A radioisotope calibrator (CRC-25R or CRC-55tR Capintec Inc., Ramsey, NJ, USA) was used to measure samples above 50 kBq.
[0180] To determine real time distribution of .sup.224Ra and .sup.212Pb in samples, high purity germanium detectors (HPGe) were used (a Broad Energy Germanium detector BE3830P or a Standard Electrode Coaxial Germanium detector GC3518, Mirion-Canberra, USA). The spectroscopy analysis software package used with the instruments was based on Genie algorithms.
Example 5—Labeling with .SUP.224.Ra: Surface Labeled, Inclusion Labeled and Layer Protected CaCO.SUB.3 .Microparticles
[0181] Radium-224 labeled CaCO.sub.3 microparticles were prepared by three different procedures: [0182] 1. Surface labeling by adsorption of .sup.224Ra onto the surfaces of pre-prepared CaCO.sub.3 microparticles. [0183] 2. Inclusion labeling by incorporation of .sup.224Ra into the CaCO.sub.3 microparticles during their formation. [0184] 3. Surface labeled CaCO.sub.3 microparticles where after radiolabeling a layer of CaCO.sub.3 is precipitated onto the original surfaces to encapsulate the radionuclide.
[0185] For surface labeling, the CaCO.sub.3 microparticles were washed three times with water and two times with 0.1 M Na.sub.2SO.sub.4 (Merck) immediately before radiolabeling. Radium-224 solution (in 0.1 M HCl with 0.035-0.5 M NH.sub.4OAc) was added to the microparticles under the presence of 0.004 w/w % Ba.sup.2+ and 0.6 w/w % SO.sub.4.sup.2− (Merck) relative to CaCO.sub.3 for coprecipitation of .sup.224Ra.sup.2+ on the surface of the microparticles. The radiolabeling process took place in a solution of 0.9% saline (Merck) under orbital rotation for 1.5 h (HulaMixer, Invitrogen, Thermo Fisher Scientific, MA, US).
[0186] Inclusion-labeled CaCO.sub.3 microparticles were prepared by rapidly pouring a desired volume of 0.33 M or 1 M CaCl.sub.2 solution containing 0.004 to 0.3 w/w % Ba.sup.2+ (relative to CaCO.sub.3) and desired amount of .sup.224Ra into an equal volume of 0.33 M or 1 M Na.sub.2CO.sub.3 solution containing 0.6 to 0.7 w/w % SO.sub.4.sup.2− (relative to CaCO.sub.3) while mixing with a magnetic stirrer (BioSan MS3000, Riga, Latvia) or by hand shaking and vortexing. In some applications 1 mg/ml gelatin (Sigma-Aldrich) was added in the CaCO.sub.3 crystallization phase to slow down the crystallization and stored in refrigerator overnight.
[0187] Layer protected CaCO.sub.3 microparticles were surface labeled with .sup.224Ra and excess labeling solution was removed. Subsequently, the microparticles were dispersed in a solution containing CO.sub.3.sup.2− and Ca.sup.2+ ions at concentrations from 0.33-0.66 M under vigorous stirring, in order to precipitate a thin layer of CaCO.sub.3 to cover the original surfaces.
[0188] In all cases, excess layering or labeling solution was removed before the CaCO.sub.3 microparticles were washed once or twice with 0.9% NaCl respectively before dispersion in NaCl or NaCl supplemented with a phosphorus compound. In some cases when two washing steps were performed, the phosphorus compound was added after the first washing step and thereby the microparticles were subjected to an additional wash. Finally, the radiolabeled microparticle suspension was autoclaved.
Example 6—Size Control of CaCO.SUB.3 .Microparticles with EDTMP, Pamidronate and SHMP
[0189] Calcium carbonate microparticles were washed three times with water for injection (WFI), and in some cases additionally two times in 0.1 M sodium sulfate, before suspension in a solution of additive (EDTMP, pamidronate or SHMP) with varying concentration, in 0.9% NaCl. For comparison, samples with zero additive added were suspended in 0.9% NaCl only. Microparticle concentration varied from 30 to 250 mg/ml. The suspension was autoclaved at 121° C. for 21 min. In some cases, measurements were made on CaCO.sub.3 microparticles that were surface labeled with 224Ra as described in Example 5.
[0190] Particle size of the autoclaved suspension was measured by use of a laser diffraction particle size analyzer (Mastersizer 3000, Malvern Instruments Ltd, Worcestershire, UK), up to 8 days after suspension had been prepared and stored at room temperature. Additive and additive concentration, microparticle size distribution and day of measurement are summarized Table 2Error! Reference source not found. For comparison, the median volume-based diameter of unprocessed CaCO.sub.3 microparticle raw material when suspended in water is also given. In the absence of additives, the sample preparation immediately caused a 3-fold increase in median particle size, with even larger microparticles after 5 days because of continuing growth in the aqueous medium. By adding the additives EDTMP, SHMP or pamidronate, microparticle size was stabilized with respect to the unprocessed raw material. Impact of additive concentration is most evident for EDTMP; while a concentration of 0.001 g/g relative to CaCO.sub.3 was unable to stabilize the microparticle size 5 days after sample preparation, the size remained stable for EDTMP concentration of >0.013 g/g up to at least 8 days.
TABLE-US-00002 TABLE 2 Impact of different phosphorus additives on the size distribution of CaCO.sub.3 microparticles after autoclaving. Median diameter (μm), Additive Median number of days after sample concentration per diameter (μm) of preparation Additive CaCO.sub.3 mass (g/g) raw material 0 5/6 7/8 No additive n/a 5.0 16.5 22.5 EDTMP 0.001 5.0 6.5 18.3 0.013 5.0 3.9 3.9 0.014.sup.(a) 4.0 3.6 3.4 0.024.sup.(a) 4.8 4.6 4.7 0.046 5.0 4.2 3.9 SHMP 0.015.sup.(a) 4.8 4.3 0.030.sup.(a, *) 4.8 4.2 4.7 0.050.sup.(b) 5.6 6.1 6.2 0.100.sup.(b) 5.6 6.6 6.5 0.200 5.0 4.2 4.1 Pamidronate 0.008 6.7 5.2 5.1.sup.(c) 0.009.sup.(c) 5.0 4.4 4.3 0.016 6.7 5.2 5.0.sup.(c) .sup.(a)Surface labeled microparticles, * Mock labeling process without .sup.224Ra. .sup.(b)Includes an additional washing step with WFI after addition of the additive to remove any unbound additive, may influence final additive concentration. .sup.(c)Measured on day 13.
Example 7—Retention of Radioactivity on CaCO.SUB.3 .Microparticles In Vitro: Impact of Phosphorus Compounds as Additives
[0191] Radiolabeling of CaCO.sub.3 microparticles, including surface labeling, inclusion labeling or layer protected, was performed as described in Example 5. Microparticles were suspended at a concentration from 12.5-250 mg/ml, in 0.9% NaCl with relative additive (EDTMP, pamidronate or SHMP) concentration ranging from 0-0.100 g/g with respect to CaCO.sub.3. The suspension was autoclaved and left in room temperature. To determine the retention of .sup.224Ra and .sup.212Pb on the microparticles, a sample aliquot was withdrawn at different time points after autoclaving. Subsequently, microparticles were separated from the liquid phase by centrifugation, and the radioactivity in the obtained pellet fraction and supernatant fraction was measured separately using either a HPGe detector or the Hidex automated gamma counter (see Example 4 for details). The percentage retained radioactivity on microparticles was defined as the ratio of activity in the pellet fraction to that in the whole sample before separation.
[0192] An overview of the retained radioactivity from both .sup.212Pb and .sup.224Ra on surface labeled and layer protected CaCO.sub.3 microparticles is given in Table 3 and Table 4 respectively. Addition of a phosphorus compound did not influence the percentage of retained radioactivity on the microparticles the first week after sample preparation, perhaps with the exception of a tendency towards lower degree of .sup.212Pb retention with higher EDTMP amounts. All tested additive amounts were able to control the size of the microparticles (see Example 6).
TABLE-US-00003 TABLE 3 Impact of different phosphorus additives on the retention of radioactivity on surface labeled CaCO.sub.3 microparticles in vitro. Relative additive % Retained .sup.212Pb/.sup.224Ra on the microparticles, concentration number of days after sample preparation Additive (g/g) 0/1 3 5 7/8 No additive NA 99%/86% 99%/91% EDTMP 0.012 80%/97% 77%/95% SHMP 0.015 99%/98% 0.020 100%/100% 100%/100% 0.100.sup.(a) 97%/86% 98%/85% Pamidronate 0.009.sup.(a) 100%/90% 100%/100% .sup.(a)Includes additional centrifugation after addition of the additive to remove any excess, may influence final additive concentration.
TABLE-US-00004 TABLE 4 Impact of EDTMP on the retention of radioactivity on layer protected CaCO.sub.3 microparticles in vitro. % Retained .sup.212Pb/.sup.224Ra on Relative additive the microparticles, number concentration of days after sample preparation Additive (g/g) 0/1 3 7 EDTMP 0.012 96%/99% 96%/99% 0.020 95%/90% 98%/96% 0.050 83%/97% 64%/97%
Example 8—Biodistribution of Intraperitoneally Administered .SUP.224.Ra-Labeled CaCO.SUB.3 .Microparticles in Mice
[0193] Institutionally bred, healthy female athymic nude Foxn.sup.nu mice were used. The mice were administered different variants of .sup.224Ra—CaCO.sub.3-microparticles or cationic .sup.224Ra intraperitoneally (IP) (see Table 5 for details) and approximately one day post injection blood was collected by cardiac puncture while the animals were under anesthesia. Immediately after, the animals were euthanized before selected organs and tissues were collected, weighed and the radioactivity measured with the Hidex gamma counter. The percent of injected dose per gram tissue of .sup.224Ra and daughter nuclide with the longest half-life .sup.212Pb (10.6 hours) was estimated. Measurements of the samples as soon as possible after time of sacrifice were used to estimate the amount of .sup.212Pb, whereas a re-measurement minimum 2 days after time of sacrifice were used to determine the amount of .sup.224Ra. The measured radioactivity was compared directly to the radioactivity in standard samples of the injectate which were measured alongside the samples.
TABLE-US-00005 TABLE 5 Overview of performed biodistribution experiments with cationic .sup.224Ra and different variants of .sup.224Ra-labeled CaCO.sub.3 microparticles. Number Mice Administered CaCO.sub.3 Additive of mice age activity microparticles concentration per Group per group (weeks) [kBq/mouse] [mg/mouse] CaCO.sub.3 mass (g/g) Cationic .sup.224Ra 4 7- 3-24 0 n/a Surface labeled 2 5 16 1 n/a .sup.224Ra-CaCO.sub.3- 3 5-48 16 5 n/a MP Layer protected 3 7 6.3 1 0.012 surface labeled 3 7 7.2 6 0.012 .sup.224Ra-CaCO.sub.3- 6 7-13 13-17 12 0.012 MP in in EDTMP Surface labeled 3 11 11 5 0.1 .sup.224Ra-CaCO.sub.3- 3 11 10 5 0.2 MP washed 3 11 10 5 0.4 with SHMP Inclusion 3 10-13 39 4 0.08 labeled .sup.224Ra- CaCO.sub.3-MP in EDTMP MP: Microparticles
[0194] The ex vivo biodistribution data shows that the tissue distribution was largely similar between the .sup.224Ra—CaCO.sub.3-microparticles with (
Example 9—Therapeutic Effect of Radiolabeled Microparticles Dispersed in Phosphorus Compounds in an Ovarian Cancer Xenograft Model in Mice
[0195] Human ovarian cancer often leads to ascites and therefore the therapeutic effect of radiolabeled microparticles dispersed in phosphorus compounds was examined in an ovarian cancer xenograft model that produces aggressive tumor cell growth established as ascites in immunodeficient mice.
[0196] Xenografts were generated by a single IP injection of ES-2 cell suspension (1×10.sup.6 cells in 0.2 ml RPMI) in institutionally bred, 4-5 weeks old female athymic nude Foxn.sup.nu mice. Approximately one day later, mice were treated with intraperitoneal injections of different variants of .sup.224Ra-labeled CaCO.sub.3 microparticles (Table 5). Mice in the control group was administered 0.9% NaCl IP. Therapeutic effect was evaluated by survival time. The mice were monitored for changes in bodyweight, behavior, posture, and appearance minimum twice per week and more frequently when they displayed signs indicating disease progression. When mice reached predetermined endpoints, which included rapid body weight loss (>10% within one week), severely impaired mobility due to ascites build-up and/or cachexia, they were euthanized by cervical dislocation.
[0197] Survival times were recorded as days after tumor cell inoculation, and Kaplan-Meier survival curves are presented in
TABLE-US-00006 TABLE 6 Summary of selected study details and results: Efficacy of .sup.224Ra-CaCO.sub.3-microparticles in human ovarian xenograft model ES-2 in immunodeficient nude mice. Number Radioactivity of mice Administered based on CaCO.sub.3 Median per volume standards.sup.1 (s.d.) microparticles survival Group group [ml/mouse] [kBq/mouse] [mg/mouse] [days] 0.9% NaCl 6 0.40 n/a n/a 17.5 Surface labeled .sup.224Ra- 5 0.30 13.7 (0.4) 4.1 27.0* CaCO.sub.3-MP in 0.9% NaCl Surface labeled .sup.224Ra- 6 0.30 17.9 (1.2) 4.1 27.5* CaCO.sub.3-MP washed with SHMP Inclusion labeled .sup.224Ra- 6 0.45 15.4 (3.4) 5.6 28.5* CaCO.sub.3-MP washed with SHMP Layer protected .sup.224Ra- 6 0.30 17.4 (2.2) 9.0 28.5* CaCO.sub.3-MP in EDTMP Inclusion labeled .sup.224Ra- 6 0.35 20.7 (1.4) 4.4 27.5* CaCO.sub.3-MP in EDTMP .sup.1Administered radioactivity per mouse is based on measurements of three standard samples per group on the Hidex Automated Gamma Counter five days post injection. The measurement of each standard was decay corrected to time of injection and the average of these are reported with the corresponding standard deviation. *Statistically significant compared to saline control group with a family-wise significance level of 0.05. Survival curves were compared pairwise by log-rank tests and adjusted for multiple comparisons by the Bonferroni method.
Example 10—Antitumor Efficacy of Radiolabeled Microparticles Dispersed in Phosphorus Compounds in a Syngeneic Colon Carcinoma Model in Mice
[0198] Colorectal cancer frequently results in metastases in the peritoneal cavity and hence the therapeutic effect of radiolabeled microparticles dispersed in phosphorus compounds was examined in a syngeneic model of IP colon carcinoma in immunocompetent mice.
[0199] Tumors were established by a single IP injection of the murine colorectal cancer cell line CT26.WT (5×10.sup.4 cells in 0.2 ml PBS) in female BALB/cAnNRj mice (Janvier Labs, France) of approximately 6 weeks age. One day later, mice were treated with intraperitoneal injections of different variants of .sup.224Ra-labeled CaCO.sub.3 microparticles (Table 7). Mice in the control group was administered 0.9% NaCl IP. Efficacy, as measured by survival time, was based on rapid change in body weight, development of ascites, scoring of physical appearance and development of palpable tumors in the abdomen. When mice reached these predetermined endpoints, they were euthanized by cervical dislocation.
[0200] Survival times were recorded as days after tumor cell inoculation, and Kaplan-Meier survival curves are presented in
TABLE-US-00007 TABLE 7 Summary of selected study details and results: Efficacy of intraperitoneally administered .sup.224Ra-labeled CaCO.sub.3 microparticles in a syngeneic CT26.WT colon carcinoma tumor model in BALB/c mice. Number Radioactivity of mice Administered based on CaCO.sub.3 Median per volume standards.sup.1 (s.d.) microparticles survival Group group [ml/mouse] [kBq/mouse] [mg/mouse] [days] 0.9% NaCl 7 0.40 n/a n/a 18.0* Surface labeled .sup.224Ra- 8 0.40 26.4 (2.5) 5.0 27.0 CaCO.sub.3-MP in 0.9% NaCl Surface labeled .sup.224Ra- 8 0.40 25.8 (4.4) 5.0 29.5 CaCO.sub.3-MP washed with SHMP Layer protected .sup.224Ra- 8 0.45 21.5 (4.1) 13.5 33.0 CaCO.sub.3-MP in EDTMP Inclusion labeled .sup.224Ra- 8 0.30 24.8 (2.9) 3.8 32.5 CaCO.sub.3-MP in EDTMP .sup.1Administered radioactivity per mouse is based on measurements of three standard samples per group on a Wizard 2 gamma counter three days post injection. The measurement of each standard was decay corrected to time of injection and the average of these are reported with the corresponding standard deviation.
Example 11—Lead-212 Labeled Calcium Carbonate Microparticles in Pamidronate
[0201] Calcium carbonate microparticles and .sup.212Pb solution were produced as described earlier in Examples 1 and 3. Dry CaCO.sub.3 microparticles were suspended in WFI, ultrasonicated and washed a total of three times with WFI. Microparticles were finally suspended in 0.9% NaCl at a concentration of 25-50 mg/ml, and pamidronate disodium was added to the suspension for a relative pamidronate/CaCO.sub.3 concentration of 0.01 g/g. In a sealed headspace vial, the suspension was autoclaved at 121° C. for 20 min before being cooled down to room temperature. Lead-212 solution was pH neutralized by adding 5M ammonium acetate and 1M sodium hydroxide, 10 v/v % of each. In the radiolabeling process, a volume of .sup.212Pb solution corresponding to approximately 50% of the microparticle suspension was added to the sealed container with microparticle suspension by use of a syringe, after which the suspension was vortexed and placed on a horizontal shaker for 3 to 60 min. The activity per microparticle mass varied from 3-99 kBq/mg. In some cases, the microparticle suspension was further diluted with 0.9% NaCl after labeling procedure.
[0202] Yield of the radiolabeling was evaluated by separating the liquid phase from the microparticles in a small sample aliquot of suspension (supernatant S and particle pellet P). The radioactivity was measured on both fractions by use of either a HPGe detector or a Hidex automated gamma counter. The yield of the radiolabeling was evaluated as CPM (P)/CPM(S)+CPM(P), where CPM denotes counts per minute.
[0203] In Table 8, an overview of the yield of the radiolabeling is given. Incubation time during horizontal shaking does not influence the radiolabeling yield, but there is a trend of improved yield with higher activity concentration.
TABLE-US-00008 TABLE 8 Yield of .sup.212Pb labeling of CaCO.sub.3 microparticles added pamidronate for size control. CaCO.sub.3 .sup.212Pb activity microparticle to CaCO.sub.3 Duration of Yield of concentration mass ratio radiolabeling radiolabeling 18 mg/ml 3 kBq/mg 3 min 94% .sup.(1) 18 mg/ml 3 kBq/mg 30 min 94% .sup.(1) 18 mg/ml 3 kBq/mg 60 min 94% .sup.(1) 25 mg/ml 41 kBq/mg 3 min 99% 25 mg/ml 99 kBq/mg 3 min 100% .sup.(1) Average from two parallel radiolabeled samples.
Example 12—Size Control of Radiolabeled Calcium Carbonate Microparticles with and without Addition of a Calcium Carbonate Layer by Addition EDTMP
[0204] The size of unlabeled, mock labeled, and radiolabeled CaCO.sub.3-MPs (MPs: microparticles) in suspension with varying concentration of EDTMP was measured with laser diffraction (Mastersizer 3000, Malvern Instruments Ltd., Worcestershire, UK). The unautoclaved CaCO.sub.3-MPs used as raw material for radio- and mock labeling were used as reference, by dispersing a small amount of dried CaCO.sub.3-MPs in water and ultrasonicating to disperse. Size stability over time was evaluated in radiolabeled CaCO.sub.3-MPs by measuring after seven days of storage at room temperature; surface labeled MPs were compared with layer encapsulated MPs.
[0205] The ability of EDTMP to control size of calcium carbonate microparticles that have been radiolabeled with radium-224 and further encapsulation by addition of a layer of calcium carbonate before sterilization of the suspension by autoclaving was examined.
[0206] This example shows that size control by EDTMP also is achieved for a radioalabeled, and layer encapsulated product.
Example 13—Size Control of Calcium Carbonate Microparticles by Addition of EDTMP Slow Down Sedimentation Rate of Microparticles in Suspension
[0207] The ability of MPs to remain suspended in solution was evaluated by the sedimentation rate, which was investigated by visual inspection of samples and by evaluating the turbidity of different suspensions of non-radioactive mock labeled CaCO.sub.3-MPs, with and without EDTMP. Turbidity was assessed by diluting the CaCO.sub.3-MP suspension with water (water for injection), and then measuring the change in optical density at a wavelength of 800 nm over 30 min using a spectrophotometer (Hitachi U-1900, Hitachi High-Tech, Tokyo, Japan). The 800 nm wavelength was chosen to reduce potential light absorbance by CaCO.sub.3 and improve light scattering by particles. A decrease in optical density with time is, therefore, directly related to decreased light scattering by MPs, and thereby a decreased turbidity of the sample due to sedimentation. See
[0208] This example shows that the sedimentation rate is reduced by reduction of particle size. There are improved features for handling of suspension with advantage in terms of clinical administration of the product.
Example 14—Radiochemical Properties Depending on EDTMP and Layer Encapsulation
[0209] Radiochemical purity was defined as the percentage of radionuclides retained on the MPs after a certain period. A small aliquot of suspension was separated into MP fraction P and supernatant fraction S by centrifugation. The percentage radiochemical purity, % RCP, was defined as the proportion of radioactivity in the P fraction:
[0210] CPM(P)/CPM(P+S), with CPM denoting counts per minute. The radioactivity in the two fractions was measured separately using a Hidex Automatic Gamma Counter (Hidex Oy, Turku, Finland). Radioactivity of .sup.212Pb was quantified by counts in the 60-110 keV window. For .sup.224Ra, radioactivity was determined indirectly by assuming transient equilibrium between .sup.224Ra and progeny .sup.212Pb after allowing the two fractions to decay for at least two days, and then measuring .sup.212Pb activity in the 65-345 keV window, in which gamma energy and X-rays mainly originated from this daughter. Sampling and measurement were repeated after up to seven days of storage at room temperature to evaluate the stability of .sup.212Pb and .sup.224Ra % RCP over time.
[0211] The complexation between released .sup.212Pb from MPs and EDTMP in the solution was evaluated in the liquid phase of different variants of .sup.224Ra—CaCO.sub.3-MPs (
[0212] This example shows a comparison of retention of .sup.212Pb and .sup.224Ra on CaCO.sub.3 microparticles with or without a layer encapsulation, showing how retention of in particular .sup.212Pb is improved by addition of the layer in a product in EDTMP.
Example 15—Biodistribution of Radium-224 and Lead-212 after i.p. Injection of Layer Encapsulated .SUP.224.Ra—CaCO.SUB.3.-MPs in EDTMP
[0213] The biodistribution of layer encapsulated .sup.224Ra—CaCO.sub.3-MPs with added EDTMP was evaluated in institutionally bred female athymic nude mice (Hsd: Athymic Nude-Foxn1nu). Calcium carbonate microparticles were labeled and autoclaved as de-scribed earlier. The impact of mass dose (mg dose) was considered by testing doses rang-ng from 1-12 mg CaCO.sub.3 and 6-18 kBq by creating dilutions with an isotonic infusion solution (Plasmalyte, Baxter International Inc., IL, United States). One day after a single i.p. administration, the mice were euthanized by cervical dislocation and tissue samples were obtained to measure radioactivity. Three standard samples corresponding to 25-50% of the administered dose of each treatment were used to determine the injected radioactivity dose. The radioactivity of .sup.212Pb and .sup.224Ra of tissue and standard samples was measured using a gamma counter as described above, from which the percentage injected dose per gram tissue (% ID/g) was calculated. Correction for decay and/or ingrowth of .sup.224Ra and .sup.212Pb was not performed in the calculation of the % ID/g for two reasons. Firstly, standard samples and tissue samples were counted with less than 2-3 h time interval (i.e., 3% of the half-life of 224Ra) and secondly, error propagation as a result of uncertainty in the measurement of .sup.224Ra when the measured activity was close to or below the limit of quantification of the instrument could be avoided. As a reference for the skeletal accumulation of free .sup.224Ra one day after i.p. injection, one group of mice received ˜30 kBq .sup.224RaCl.sub.2 prepared as described previously be Westrøm et al. See
[0214] This example shows a comparison of the biodistribution of both radium-224 and lead-212 between different amount of layered encapsulated microparticles and free radium-224. Reduced levels of bone uptake with increasing amount of microparticles.
Example 16—Distribution of 208Pb and .SUP.212.Pb on Layer Encapsulated Microparticles with 2.5% (w/w) EDTMP
[0215] The cumulative amount of the chemically equivalent stable daughter nuclide .sup.208Pb adsorbed on the MPs increases with time, although this seems to have little effect on the adsorption of .sup.212Pb. For the surface labeled variant at this EDTMP concentration, % RCP of .sup.212Pb was only 56% on day zero, with an increase to 70% on day four.
Example 17—Adsorption of .SUP.212.Pb.SUP.2+ and 212.Pb-EDTMP to Calcium Carbonate Microparticles
[0216] The known complexation property of EDTMP with both .sup.212Pb and calcium indicates that it is also possible for the .sup.212Pb-EDTMP complex to associate with the MPs. To test this hypothesis, adsorption of .sup.212Pb on non-radioactive mock labeled CaCO.sub.3-MPs, both with and without layer encapsulation, was evaluated after the addition of a solution of .sup.212Pb-EDTMP. It was found that 17-20% of the .sup.212Pb-EDTMP adsorbed on the MPs; the adsorption increased to 96% when unbound .sup.212Pb.sup.2+ (.sup.212PbCl.sub.2) was added instead. The reduced adsorption of .sup.212Pb-EDTMP is in line with the general observation that the % RCP of .sup.212Pb of both surface labeled MPs and layer encapsulated MPs decreased at higher EDTMP concentrations in the MP suspension.
Example 18—Preparation of Smaller Microparticles (CaCO.SUB.3 .SMPs)
[0217] Calcium carbonate microparticles has been produced by two different procedures to create particles with two distinct size populations. One procedure of CaCO.sub.3 microparticles production was as detailed in Example 1, the other procedure was similar to the first, however, glycerol was added during the spontaneous precipitation reaction in an attempt to produce smaller microparticles (CaCO.sub.3 SMPs). Before mixing 1 M solutions of CaCl.sub.2) and Na.sub.2CO.sub.3 (Merck), glycerol (Sigma-Aldrich) was added to each solution to a concentration of 50% (v/v), diluting the solutions to 0.5 M. The two solutions were then combined under vigorous stirring with an overhead stirrer operating at 6000 RPM for 30 min. The resulting precipitate of CaCO.sub.3 SMPs was washed three times with water for injection (WFI) before drying at 180° C. Size distribution of microparticles were measured by a laser diffraction particle size analyzer (Mastersizer 3000, Malvern Instruments Ltd, Worcestershire, UK). The CaCO.sub.3 MP and CaCO.sub.3 SMPs used in Example 19, 20 and 21 had volume-based median diameter of approximately 5 μm and 2 μm, respectively. Labeling with .sup.212Pb was performed as described in example 11.
Example 19—Radiochemical Properties of Various CaCO.SUB.3 .Particles in Suspension after Autoclaving and Labeling with .SUP.212.Pb
[0218] Measurements of the .sup.212Pb radiolabeled particles (produced as in Example 1 or Example 18 and labeled as described in Example 11) included determination of radioactivity concentration, radiochemical yield/purity, over-time-stability, and possible breakthrough of the parent nuclide .sup.224Ra. Radioactivity level of .sup.212Pb solution and the vial of labeled CaCO.sub.3 particles in suspension was measured using an ionization chamber dose calibrator (Capintec Inc., NJ, USA). Percentage radiolabeling yield, % RCY, was determined by separating a small aliquot of suspension into particle fraction P and supernatant fraction S to measure the portion of adsorbed .sup.212Pb on the particles. The two fractions were measured separately on an automatic gamma counter (Hidex Automatic Gamma Counter, Hidex Oy, Turku, Finland). % RCP was calculated as the ratio CPM(P)/CPM (P+S), where CPM denotes counts per minute in each fraction, to denote the fraction of adsorbed .sup.212Pb on the particles.
[0219] In vitro stability was defined as the percentage retained .sup.212Pb on microparticles in an in vitro setup consisting of incubation of .sup.212Pb—CaCO.sub.3 MPs/SMPs in an isotonic infusion solution (Plasmalyte, Baxter, IL, USA) with pH of approximately 7 supplemented with 10 g/L human serum albumin (Sigma-Aldrich, MO, USA) in 37° C. environment for 1.5-21 h. Dilution was performed from an initial CaCO.sub.3 concentration of 25 mg/ml down to of 2 mg/ml or 6 mg/ml. The diluted particles were separated from incubation solution and radioactivity in the two parts were measured as described above for determination of RCP.
[0220] All the variants had a .sup.212Pb % RCP of >90% in these experiments, dilution and incubation at 2-6 mg/ml resulted in release of .sup.212Pb into the incubation solution that appeared to be particle type and concentration dependent. Retention of .sup.212Pb on particles was lowest for the largest recrystallized particles and the lowest concentrations, with negligible contribution from prolonged duration of the incubation from 90 min to 21 h. The retention of .sup.212Pb on vaterite microparticles was high with a trend of higher stability for the SMPs compared to the MPs.
[0221] The results are shown in
Example 20—Biodistribution of Intraperitoneally Administered .SUP.212.Pb-Labeled CaCO.SUB.3 .Microparticles in Mice
[0222] .sup.212Pb—CaCO.sub.3 MPs and .sup.212Pb—CaCO.sub.3 SMPs was labeled as in Example 11. The biodistribution of lead-212 was evaluated after i.p. administration of .sup.212Pb—CaCO.sub.3 MPs to tumor-free mice and compared to i.p. administration of free .sup.212Pb.sup.2+ in 0.9% NaCl (.sup.212PbCl.sub.2). A dose of 5 mg .sup.212Pb—CaCO.sub.3 MPs with volume-based median particle diameter of 5 μm was investigated. Mice were sacrificed by cervical dislocation two, six, and 24 hours after the treatment and tissue samples were collected for radioactivity measurements and calculation of the percentage injected dose per gram tissue (% ID/g). In a second experiment, the biodistribution of 5 mg .sup.212Pb—CaCO.sub.3 MPs and .sup.212Pb—CaCO.sub.3 SMPs with volume-based median diameter below 3 μm were compared. Radioactivity measurements were performed with a Hidex automatic gamma counter with appropriate calibration factor to obtain Bq data. The measurements were decay corrected using the 10.6 h half-life of .sup.212Pb. Re-measurement of kidney and liver samples was performed after >24 h of decay to ensure transient equilibrium between .sup.212Pb and daughters. High levels of .sup.212Pb could be detected in the kidneys two hours after .sup.212PbCl.sub.2 was injected and with considerable amounts in the blood, liver, and skeleton. The % ID/g was significantly reduced in these tissues as well as in the spleen for the MP-bound .sup.212Pb. After 6 h, the levels of .sup.212Pb in the kidneys were reduced for both variants, indicating clearance, but remained stable in the skeleton and with significantly higher % ID/g for MP-bound .sup.212Pb compared to .sup.212PbCl.sub.2 in these tissues. After 24 h, i.e., more than two physical half-lives of .sup.212Pb, the % ID/g in most of the soft tissues was reduced and no statistical difference between the MP-bound and free variant was detected apart from in the skull (p<0.020), and the .sup.212Pb accumulated in the skeleton had increased with respect to the earlier timepoints for the MPs.
[0223] The results are shown in
Example 21—Therapeutic Efficacy of Intraperitoneally Administered .SUP.212.Pb-Labeled CaCO.SUB.3 .Microparticles in Mice
[0224] A study of the therapeutic efficacy of .sup.212Pb—CaCO.sub.3 MPs 1% pamidronate for treatment of cavitary cancers was performed in an i.p. xenograft mouse model of ovarian cancer. Nude mice were inoculated i.p. with 300,000 ES-2 cells (ATCC, Wesel, Germany) and treated with a single i.p. dose of 2-5 mg and 63-430 kBq .sup.212Pb—CaCO.sub.3 MPs the day after. All radioactivity doses were measured and calculated retrospectively from standard samples as described above. Control animals were given saline or non-labeled CaCO.sub.3 MPs suspended in saline and 1% (w/w) pamidronate. Significant therapeutic effect was observed for all of the tested doses of .sup.212Pb—CaCO.sub.3 MPs in pamidronate compared to the saline control and non-labeled CaCO.sub.3 MPs with pamidronate. The effect appeared dose dependent for the labeled MPs.
[0225] The results are shown in
Items
[0226] 1. A particle comprising a degradable compound, a radionuclide, and a phosphorus containing additive. [0227] 2. The particle according to item 1, wherein the degradable compound is selected from the group consisting of CaCO.sub.3, MgCO.sub.3, SrCO.sub.3, BaCO.sub.3, calcium phosphates including hydroxyapatite Ca.sub.5(PO.sub.4).sub.3(OH) and fluoroapatite, and composites with any of these as a major constituent. [0228] 3. The particle according to items 1-2, wherein the degradable compound is CaCO.sub.3. [0229] 4. The particle according to items 1-3, wherein the phosphorus containing additive is a phosphate selected from the group consisting of orthophosphate, linear oligophosphates and polyphosphates, and cyclic polyphosphates. [0230] 5. The particle according to items 1-3, wherein the phosphorus containing additive is a polyphosphate selected from the group consisting of pyrophosphate, tripolyphosphate and triphosphono phosphate. [0231] 6. The particle according to items 1-3, wherein the phosphorus containing additive is a cyclic polyphosphate which is sodium hexametaphosphate (SHMP). [0232] 7. The particle according to items 1-3, wherein the phosphorus containing additive is a phosphonate. [0233] 8. The particle according to item 7, wherein the phosphonate is a bisphosphonate. [0234] 9. The particle according to item 8, wherein the bisphosphonate is selected from the group consisting of Etidronate, Clodronate, Tiludronate, Pamidronate, Neridronate, Olpadronate, Alendronate, Ibandronate, Risedronate, and Zoledronate. [0235] 10. The particle according to item 7, wherein the phosphonate is a polyphosphonate. [0236] 11. The particle according to item 10, wherein the polyphosphonate is selected from the group consisting of EDTMP-ethylenediamine tetra(methylene phosphonic acid), DOTMP-1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetrayl-tetrakis(methylphosphonic acid) and DTPMP-diethylenetriaminepenta(methylene-phosphonic acid). [0237] 12. The particle according to items 1-11, wherein the radionuclide is selected from the group consisting of .sup.225Ra, .sup.224Ra, .sup.223Ra, .sup.225Ac, .sup.212Bi, .sup.227Th, .sup.211At, .sup.213Bi, .sup.212Pb, .sup.64Cu, .sup.67Cu, .sup.166Ho, .sup.177Lu .sup.32P, .sup.186Re, .sup.188Re, .sup.153Sm, .sup.89Sr, .sup.161Tb, .sup.90Y, .sup.220Rn, .sup.216Po, .sup.212Po, .sup.208Tl, .sup.18F, .sup.67Ga, .sup.86Y, .sup.99mTc, .sup.111In, .sup.203Pb, .sup.83Sr, .sup.152Tb and .sup.155Tb. [0238] 13. The particle according to items 1-12, wherein the radionuclide is selected from the group consisting of alpha-radionuclides suitable for therapy consisting of .sup.225Ac, .sup.211At, .sup.213Bi, .sup.212Bi, .sup.225Ra, .sup.224Ra, .sup.223Ra and .sup.227Th. [0239] 14. The particle according to items 1-12, wherein the radionuclide is selected from the group consisting of beta-radionuclides suitable for therapy consisting of .sup.64Cu, .sup.67Cu, .sup.166Ho, .sup.177Lu, .sup.32P, .sup.186Re, .sup.188Re, .sup.153Sm, .sup.89Sr, .sup.161Tb, .sup.90Y. [0240] 15. The particle according to items 1-12, wherein the radionuclide is a beta emitter with alpha-progenies suitable for therapy which is .sup.212Pb. [0241] 16. The particle according to items 1-12, wherein the radionuclide is selected from the group consisting of alpha-emitting .sup.224Ra with the progeny radionuclides .sup.220Rn, .sup.216Po, .sup.212Pb, .sup.212Bi, .sup.212Po and .sup.208Tl. [0242] 17. The particle according to items 1-12, wherein the radionuclide is selected from the group consisting of radionuclide suitable for imaging consisting of .sup.18F, .sup.67Ga, .sup.86Y, .sup.99mTc, .sup.111In, .sup.203Pb, .sup.83Sr, .sup.152Tb and .sup.155Tb. [0243] 18. The particle according to any one of items 1-17, wherein the size of the particle is from 1 nm to 500 μm. [0244] 19. The particle according to any one of items 1-18, wherein the degradable compound is selected from the group consisting of PEG modified CaCO.sub.3, protein modified CaCO.sub.3 including mAbs and Fabs, carbohydrate modified CaCO.sub.3, lipid modified CaCO.sub.3, vitamin modified CaCO.sub.3, organic compound modified CaCO.sub.3, polymer modified CaCO.sub.3 and/or inorganic crystal modified CaCO.sub.3. [0245] 20. A composition comprising one or more particles according to any one of items 1-19. [0246] 21. A composition which is a pharmaceutical composition comprising one or more particles according to any one of items 1-19 and a diluent, carrier, surfactant, and/or excipient. [0247] 22. The pharmaceutical composition according to item 21 or the composition according to items 15, prepared with an amount of radionuclide that is 1 kBq to 10 GBq per dosing or with an amount of radionuclide that is 50 MBq to 100 GBq suitable for multidose industrial scale production. [0248] 23. The composition according to items 20, or pharmaceutical composition according to anyone of items 21-22, wherein the composition is a particle suspension comprising monodisperse or polydisperse particles as defined in items 1-19. [0249] 24. The composition or pharmaceutical composition according to any one of items 20-23, which is suitable for parenteral use, for instance for intravenous, intracavitary and/or intratumor injections. [0250] 25. The particle according to any one of items 1-19 or composition or pharmaceutical composition according to any one of items 20-24, for use as a medicament. [0251] 26. The particle according to any one of items 1-19 or composition or pharmaceutical composition according to any one of items 20-24, for use in intracavitary therapy, radioembolization or radiosynovectomy. [0252] 27. The particle according to any one of items 1-19 or composition or pharmaceutical composition according to any one of items 20-24, for use in the treatment of cancer. [0253] 28. The particle according to any one of items 1-19 or composition or pharmaceutical composition according to any one of items 20-24, for use according to items 26-27, wherein the cancer is selected from the group consisting of intraperitoneal cancers, intracranial cancers, pleural cancers, bladder cancers, cardiac cancers, cancers in the subarachnoid cavity, and non-cavitary targets such as melanoma, non-small-cell-lung cancer. [0254] 29. The particle according to any one of items 1-19 or composition or pharmaceutical composition according to any one of items 20-24, for use in imaging. [0255] 30. The particle according to any one of items 1-19 or composition or pharmaceutical composition according to any one of items 20-24, for use according to items 26-27, which is used in combination with other cancer therapies, such as chemotherapy like taxanes (e.g. paclitaxel, docetaxel), platins (e.g. carboplatin, cisplatin), doxorubicin, mitomycin), DNA repair inhibitors such as PARP inhibitors (e.g. Olaparib, Rucaparib, Niraparib, Talazoparib, Veliparib, Pamiparib, CEP 9722, E7016, and 3-Aminobenzamide), and radioimmunotherapies. [0256] 31. The particle according to any one of items 1-19 or composition or pharmaceutical composition according to any one of items 20-24, which is a medical device or is comprised in a medical device. [0257] 32. The composition or the pharmaceutical composition according to items 20-24, wherein the concentrations of phosphonates and or phosphate compounds are 1 microgram to 1000 milligram per ml, such as 0.1 mg to 10 mg per ml of final solution, or 1 microgram to 1000 milligram per gram particles in the final solution. [0258] 33. A method for preparing a particle according to any one of items 1-19, the method comprising bringing a degradable compound, a radionuclide, and a phosphorus containing additive in contact with each other with or without using a carrier for the radionuclide. [0259] 34. A method for preparing a particle according item 33, wherein a degradable compound and a radionuclide has formed a particle in an initial step, which subsequently is coated with the phosphorus containing additive. [0260] 35. A composition or suspension comprising a particle, wherein the particle comprises a degradable compound, a radionuclide and a phosphorus containing additive, and wherein the phosphorus containing additive is associated with the particle by being present in the composition or suspension. [0261] 36. The composition or suspension according to item 35, wherein the phosphorus containing additive is part of the particle. [0262] 37. The composition or suspension according to items 35-36, wherein phosphorus containing additive is part of the composition or suspension of particles. [0263] 38. The composition or suspension according to items 35-37, wherein phosphorus containing additive is part of the particle and also part of the composition or suspension of particles. [0264] 39. The composition or suspension according to items 35-38, wherein the particle suspension which is a mixture of a solid phase and a liquid phase. [0265] 40. The composition or suspension according to items 35-39, wherein the phosphorus containing additive is in the liquid phase. [0266] 41. The composition or suspension according to items 35-40, wherein the phosphorus containing additive is in the solid phase. [0267] 42. The composition or suspension according to items 35-41, wherein the phosphorus containing additive is in the solid and the liquid phases. [0268] 43. The composition or suspension according to items 35-42, wherein the phosphorus containing additive is on the surface or embedded in the particles or both on the surface or embedded in the solid phase.