Image-guided radioactive microsphere and methods of making and use thereof

Abstract

The present disclosure relates to an imageable microsphere comprising one or more radionuclides, and methods of making and using the same in transarterial radioembolization (TARE). The microsphere is a theranostic. The microsphere provides radionuclide imaging and emits therapeutic radiation.

Description

WSGR Docket No.66410-701601 IMAGE-GUIDED RADIOACTIVE MICROSPHERE AND METHODS OF MAKING AND USE THEREOF CROSS-REFERENCE

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 567,654,filed March 20, 2024, and U.S. Provisional Application No.63 / 747,336, filed January 20, 2025, all of which are entirely incorporated herein by reference. BACKGROUND

[0002] Transarterial radioembolization (TARE), also known as selective internal radiationtherapy (SIRT), is a form of brachytherapy intended for the locoregional treatment of hepatic malignancies. More specifically, TARE is an established treatment for patients with chemo- resistant and unresectable primary and secondary metastatic liver cancers, such as hepatocellular carcinoma (HCC) and liver-involved metastatic colorectal cancer (mCRC), and is increasingly being examined for other oncology applications. This procedure may offer targeted treatment that may reduce the size of tumors, relieve symptoms, and prolong survival time for liver cancer patients who have limited treatment options.

[0003] TARE therapy may consist of administering microspheres loaded with beta-emittingradionuclides through a microcatheter positioned in the hepatic artery or its branches. The microspheres may have two mechanisms of action: they occlude the distal tumor arterioles that supply blood to the tumor and emit ionizing radiation (beta particles) that cause localized damage to the targeted lesion while sparing the surrounding healthy liver parenchyma from damage. SUMMARY

[0004] The present disclosure provides the design of radioactive microspheres that areimageable and therapeutic, and can be used in transarterial radioembolization (TARE) or other therapies. The radioactive microspheres can be used to treat tumors in the liver and organs or tissues other than liver. The components of the microspheres can be adjusted or personalized to achieve better therapeutic results for the patients receiving the radioactive microspheres. When using the radioactive microspheres the medical doctors have more control of the treatment by successfully evaluating and confirming the radioactive dosage more accurately than other methods for each patient, and adjusting the radiation dosage accordingly. These radioactive microspheres are theranostics.

[0005] In an aspect, provided is a microsphere, comprising: (i) an aluminosilicate; and (ii)one or more radionuclides, wherein the microsphere is radioactive, and wherein the microsphereWSGR Docket No.66410-701601 is imageable by computerized tomography (CT) or cone-beam computed tomography (CBCT).

[0006] In another aspect, provided is a microsphere, comprising: (i) an aluminosilicate; and(ii) one or more radionuclides comprising holmium-166 (Ho-166), wherein the microsphere is radioactive.

[0007] In still another aspect, provided is a microsphere, comprising: (i) an aluminosilicate;and (ii) holmium oxide. In some embodiments, the microsphere disclosed herein comprises Ho- 166. In some embodiments, the microsphere is imageable by single-photon emission computed tomography (SPECT) or by magnetic resonance imaging (MRI) or by computerized tomography (CT) due to the presence of holmium. In some embodiments, the microsphere is imageable by intra-procedural angiography, x-ray fluoroscopy, magnetic resonance imaging (MRI), ultrasound, positron emission tomography (PET), or single-photon emission computed tomography (SPECT), or a combination thereof. In some embodiments, the microsphere remains durable following neutron irradiation with a high thermal neutron flux. In some embodiments, the microsphere is adjustable in at least one property selected from the group consisting of ratios of different types of radiation, half-life, tissue penetration depth, specific activity per microsphere, and imaging capabilities. In some embodiments, the microsphere is a theranostic. In some embodiments, the microsphere comprises a radionuclide that is imageable and emitting therapeutic radiation. In some embodiments, the microsphere is glass.

[0008] In another aspect, provided is a method comprising: administering to a subject aplurality of microspheres, wherein a microsphere of the plurality of microspheres is as in any embodiment disclosed herein.

[0009] In some embodiments, the method further comprises: imaging at least a section of theplurality of microspheres at or near an organ of the subject. In some embodiments, the organ is liver. In some embodiments, the organ is anus, arteries, appendix, adrenal gland, brain, bones, bronchi, bladder, bone marrow, bulbourethral gland, colon, cervix, clitoris, cerebellum, diaphragm, ear, eye, fallopian tube, genital, gallbladder, heart, hypothalamus, interstitium, kidney, joint, lung, larynx, ligament, lymph node, large intestine, lymphatic vessel, mouth, mesentery, mammary glands, nose, nerve, nasal cavity, ovaries, esophagus, penis, pancreas, pharynx, placenta, prostate, pineal gland, pituitary gland, parathyroid gland, rectum, skin, spleen, scrotum, stomach, spinal cord, small intestine, salivary gland, skeletal muscles, seminal vesicles, subcutaneous tissue, testes, tendons, tongue, thyroid, trachea, thymus gland, ureters, urethra, uterus, vulva, veins, vagina, vas deferens, or vestigial organ. In some embodiments, the imaging is computerized tomography (CT) imaging, cone-beam computed tomography (CBCT) imaging, radiographic imaging, intra-procedural angiography imaging, x-ray fluoroscopy imaging, magnetic resonance imaging (MRI) imaging, ultrasound imaging, positron emissionWSGR Docket No.66410-701601 tomography (PET) imaging, or single-photon emission computed tomography (SPECT) imaging, or a combination thereof. In some embodiments, the microspheres are radioactive. In some embodiments, the microsphere is a theranostic. In some embodiments, the microsphere comprises a radionuclide that is imageable and emitting therapeutic radiation. In some embodiments, the microsphere is glass. In some embodiments, the administering is via intra- arterial or intravenous delivery.

[0010] In still another aspect, provided is a method comprising: (i) in a treatment planningstep: administering to a subject, a first plurality of microspheres; and (ii) in a therapeutic treatment step: administering to the subject, a second plurality of microspheres, wherein a microsphere of the first plurality of microspheres and the second plurality of microspheres is as in any embodiment disclosed herein.

[0011] In some embodiments, the method further comprises: (a) in the treatment planningstep: imaging at least a section of the first plurality of microspheres at or near an organ of the subject; and (b) in the therapeutic treatment step: imaging at least a section of the second plurality of microspheres at or near an organ of the subject. In some embodiments, the imaging in (a) and the imaging in (b) are in real-time. In some embodiments, the imaging in (a) and the imaging in (b) are conducted in an interventional radiology (IR) suite in which the subject is being treated. In some embodiments, the first plurality of microspheres is substantially the same as the second plurality of microspheres in terms of chemical composition and / or physical characteristics. In some embodiments, the imaging in (a) and the imaging in (b) are computerized tomography (CT) imaging, cone-beam computed tomography (CBCT) imaging, positron emission tomography (PET) imaging, radiographic imaging, intra-procedural angiography imaging, x-ray fluoroscopy imaging, magnetic resonance imaging (MRI) imaging, ultrasound imaging, or single-photon emission computed tomography (SPECT) imaging, or a combination thereof. In some embodiments, the administering in (i) is via intra-arterial or intravenous delivery. In some embodiments, the administering in (ii) is via intra-arterial or intravenous delivery.

[0012] In another aspect, provided is a method comprising (a) administering to a subject amicrosphere comprising (i) alumina and silica, and (ii) one or more radionuclides, and (b) imaging a body of the subject to identify a location of the microsphere within the body of the subject.

[0013] In some embodiments, the microsphere in any of the methods disclosed herein is atheranostic. In some embodiments, the microsphere in any of the methods disclosed herein comprises a radionuclide that is imageable and emitting therapeutic radiation. In some embodiments, the microsphere in any of the methods disclosed herein is glass.WSGR Docket No.66410-701601

[0014] Additional aspects and advantages of the present disclosure will become readilyapparent to those skilled in this art from the following detailed description, wherein only illustrative embodiments of the present disclosure are shown and described. As will be realized, the present disclosure is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive. INCORPORATION BY REFERENCE

[0015] All publications, patents, and patent applications mentioned in this specification areherein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference. To the extent publications and patents or patent applications incorporated by reference contradict the disclosure contained in the specification, the specification is intended to supersede and / or take precedence over any such contradictory material. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The novel features of the invention are set forth with particularity in the appendedclaims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings (also “Figure” and “FIG.” herein), of which:

[0017] FIG. 1 shows a scanning electron microscopy (SEM) image of Synergy Spheresexample microspheres (post spheroidization).

[0018] FIG. 2 shows an anterior view CBCT reconstruction of 250 mg of Synergy Spheresexample microsphere in both the cranial and caudal poles of a left kidney of a swine post- administration.

[0019] FIG. 3 shows an anterior view CBCT reconstruction of 250 mg of Synergy Spheresexample microsphere in in the caudal pole only (microspheres in cranial pole are a separate product) of a right kidney of a swine post-administration.

[0020] FIG. 4 shows total Ho-166 radioactivity present (%) as a function of time due toradioactive decay over time in an example.

[0021] FIG. 5 shows an example X-ray diffraction (XRD) spectra for an example glassmicrosphere.

[0022] FIG. 6 SEM images of Glass No. 2 microspheres pre-irradiation.

[0023] FIG. 7 SEM images of Glass No. 2 microspheres post-irradiation.WSGR Docket No.66410-701601 DETAILED DESCRIPTION

[0024] While various embodiments of the invention have been shown and described herein,it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions may occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed. Definitions

[0025] The singular forms “a,” “an,” and “the”, as used herein, include the plural referenceunless the context clearly dictates otherwise.

[0026] When a range of values is provided, it is to be understood that each intervening valuebetween the upper and lower limit of that range, and any other stated or intervening value in that stated range is encompassed within the scope of the present disclosure. Where the stated range includes upper or lower limits, ranges excluding either of those included limits are also included in the present disclosure.

[0027] When the term “at least,” “greater than,” or “greater than or equal to” precedes thefirst numerical value in a series of two or more numerical values, the term “at least,” “greater than” or “greater than or equal to” applies to each of the numerical values in that series of numerical values. For example, greater than or equal to 1, 2, or 3 is equivalent to greater than or equal to 1, greater than or equal to 2, or greater than or equal to 3.

[0028] When the term “no more than,” “less than,” or “less than or equal to” precedes thefirst numerical value in a series of two or more numerical values, the term “no more than,” “less than,” or “less than or equal to” applies to each of the numerical values in that series of numerical values. For example, less than or equal to 3, 2, or 1 is equivalent to less than or equal to 3, less than or equal to 2, or less than or equal to 1.

[0029] As used herein, the term “substantially” generally refers to a majority of, or mostly,as in at least about 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.99%, or at least about 99.999% or more, or 100%.

[0030] The term “subject,” as used herein, generally refers to an individual who is in need ofa therapy. The subject may be a mammal or non-mammal. The subject may be human, non- human mammal, animal, ape, monkey, chimpanzee, dog, cat, bird, reptilian, amphibian, avian, or a plant.

[0031] As used herein, the term “radionuclide” generally refers to an atom with excessnuclear energy making it unstable and that undergoes radioactive decay. Radionuclides are also known as radioactive nuclides, radioisotopes, medical isotopes, or radioactive isotopes. Radioactive decay may produce a new stable nuclide, or a new unstable radionuclide, whichWSGR Docket No.66410-701601 may undergo further decay. The term “parent radionuclide,” as used herein, refers to a radionuclide that decays into a new radionuclide, or “daughter radionuclide”. Examples of parent radionuclides and their daughter radionuclides may include Mo-99 / Tc-99m, Ge-68 / Ga-68 and W-188 / Re-188, among other pairs.

[0032] As used here, the terms “theranostic,” “theragnostic,” and “theranostics” generallyrefer to an integration of therapeutics and diagnostics in a single management approach allowing an image-guided therapy and defining of treatment outcome at an early stage. These terms describe a material that combines the modalities of therapy and diagnostic imaging.

[0033] As used herein, the term “microsphere” generally refers to nanospheres (withnanometer dimension(s)), microspheres (with micrometer dimension(s)) and also larger microsphere-like particles. Nanospheres generally have a diameter of 1000 nm or less. In some embodiments, the microsphere is about 10 to 2000 μm in diameter or about 100 to 4500 μm in diameter, as characterized by electron microscopy, such as scanning electron microscopy. In some embodiments, the microsphere is from about 40 to about 250 μm in diameter. In some embodiments, the microsphere is about 45 to 100 μm in diameter. In some embodiments, the spheres can be up to about 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, and 4.5 mm in diameter.

[0034] As used herein, the term “sphere” generally refers to a particle that is substantially,although perhaps not exactly, spherical and further refers to both beads and bubbles.

[0035] As used herein, the term “bead” generally refers to a solid particle that issubstantially, although perhaps not exactly, spherical. The microspheres disclosed herein can be beads.

[0036] As used herein, the term “bubble” refers to a hollow particle that is substantially,although perhaps not exactly, spherical. The microspheres disclosed herein can be bubbles.

[0037] As used herein, the term “glass” generally refers to a noncrystalline materialexhibiting glass transition behavior, and whose principal phase(s) is primarily amorphous, such as at least 50% amorphous, at least 75% amorphous, at least 90% amorphous, at least 95% amorphous, or at least 97% amorphous by volume. In some examples, a glass according to the present disclosure is substantially free or completely free, of identifiable crystalline species. The microspheres disclosed here can be glass microspheres.

[0038] As used herein, the term “glass-ceramic” generally refers to an inorganic, metaloxide formed initially as a glass that is subsequently devitrified or otherwise made a glass- ceramic by thermal treatment such that it exhibits an at least partially crystalline phase and optionally some residual glass phase. The microspheres disclosed here can be glass-ceramic microspheres.WSGR Docket No.66410-701601

[0039] As used herein, the term “devitrify” generally refers converting at least partially froma glassy state to a crystalline state.

[0040] As used herein, the term “mole fraction” or “molar percentage” (mol%) refers to thenumber of moles of a given component in a composition divided by the total number of moles in the composition, then displayed as a fraction or percentage when appropriate.

[0041] As used herein, the term “imageable” generally refers to a property of themicrospheres disclosed herein that can be detected by an imagery device. The imagery device can be computerized tomography (CT), cone-beam computed tomography (CBCT), positron emission tomography (PET), intra-procedural angiography, x-ray fluoroscopy, magnetic resonance imaging (MRI), ultrasound, or single-photon emission computed tomography (SPECT), or others.

[0042] As used herein, the term “durable” when describing a microsphere generally refers toa property of the microsphere that is physically robust, stable to temperatures at or more than 500 ºC, and does not exhibit damage (e.g., damage is no more than 1% activity leaching) after exposure to high flux neutron irradiation conditions (φ is no less than 1 × 1014n / cm2•s for a duration of time of no less than 24 h) in a nuclear research reactor. Passive Embolization

[0043] Passive embolization is a procedure that attempts to block blood vessels feedingtumors or abnormal tissues. In this approach, blood vessels which nourish a tumor are deliberately blocked by injection of an embolic material into the vessels. The embolic material includes but is not limited to, autologous substances such as fat, blood clot, and chopped muscle fragments, artificial materials such as wool, cotton, steel balls, plastic or glass beads, tantalum powder, silicone compounds, sterile absorbable gelatin sponge, oxidized cellulose, steel coils, alcohol, lyophilized human dura mater, microfibrillar collagen, collagen fibrils, polyvinyl alcohol sponge, barium-impregnated silicon spheres and detachable balloons. The obstruction of tumor blood supply, with the simultaneous disruption in nutrient supply and waste removal, may help the destruction of the tumor cells. After the passive embolization, the size of tumor metastases may be temporarily decreased, but tumors may respond by causing the growth of new blood vessels into the treated tumor. Passive non-radioactive embolization can treat conditions such as cancer, uterine fibroids, and chronic prostatitis. In some embodiments, the non-radioactive microspheres disclosed herein may be used in passive embolization of blood vessels as microspheres. In some embodiments, the non-radioactive microspheres disclosed herein may be used to treat arteriovenous malformations, hypervascular tumors. In some embodiments, the non-radioactive microspheres disclosed herein may be used in prostate arteryWSGR Docket No.66410-701601 embolization, uterine fibroid embolization, treatment of meningiomas, or occlusion of vascular anomalies. Active Embolization

[0044] Therapeutic vascular occlusions (or embolization) may treat certain pathologicalconditions in situ. Catheters may be used, under imagery control, to position particulate occlusion agents (or emboli) in the circulatory system of a subject. In the case of tumors, vascular occlusion can suppress pain, limit blood loss on the surgical intervention to follow embolization or even bring on a tumoral necrosis and avoid the operation.

[0045] Different types of emboli include but are not limited to, liquid agents (e.g., acrylicglues, gels, viscous suspensions), particulate agents (e.g., polymers, dura mater, gelatin sponges, spheres, balloons, spirals). The dual functions of the regional distribution of drugs to and the minimization of loss from the target site can be achieved with microspheres. When introduced via a regional artery, such microspheres can be trapped within the vasculature of tissues, where they may release their drug load. Such dual action is referred to as active embolization. Microspheres may be of either a solid or porous composition, and can be made to contain dispersed drug molecules either in solution or solid form. In some embodiment, both the radioactive microspheres and the non-radioactive microspheres disclosed herein may be used in combination of a therapeutic drug. In some embodiments, the drug may be a chemotherapy drug, a gene therapy drug, a small molecule drug, a biological drug (e.g., an antibody, a cell), a peptide, a hormone or steroid, or a peptide or peptide analog. Radioembolization

[0046] Radioembolization is a minimally invasive treatment that delivers radiation directlyto cancerous tumors (e.g., liver cancer) by injecting radioactive beads called microspheres into tumor’s blood supply. The microsphere can be as small as about one-third the diameter of a human hair, or other dimensions. Over a period of several days, the microspheres emit high energy radiation to shrink the tumor. This transarterial therapy strategically attacks tumors with localized, high doses of radiation. Radioembolization may also be called intra-arterial brachytherapy, selective internal radiation therapy, targeted radiation therapy, or Y-90 treatment (using yttrium-90 as the radioactive element). In some embodiments, the radioactive beads or the non-radioactive beads disclosed here may be used in passive embolization of blood vessels. Commercially available microspheres

[0047] Therapeutic microspheres used in transarterial radioembolization (TARE) maycontain a single radioactive isotope, such as, for example, yttrium-90 or holmium-166. There are three types of therapeutic microspheres commercially available for clinical use in TARE (Table 1).WSGR Docket No.66410-701601 Table 1. Characteristics of example radioactive microspheres used clinically in TARE Mean Radionu Specific

[0048] TheraSphere®, SIR-Spheres® and QuiremSpheres® may be some of the examples.TheraSphere®may consist of aluminosilicate glass microspheres impregnated with yttrium oxide; the therapeutic radionuclide yttrium-90 (90Y, t½ = 64.1 h) may be formed by placing the microspheres in a nuclear reactor, where thermal neutrons may elicit the89Y(n,γ)90Y nuclear transformation. SIR-Spheres®may be cation exchange resin microspheres wherein90Y is adsorbed onto the surface of the microspheres via ion-exchange. QuiremSpheres®may be poly- L-lactic-acid (PLLA) polymeric microspheres wherein166Ho-acetylacetonate may be encapsulated within a PLLA shell. The therapeutic radionuclide in QuiremSpheres® is holmium-166 (166Ho, t½= 26.8 h), formed by the165Ho(n,γ)166Ho nuclear transformation when the microspheres are placed in a nuclear reactor.

[0049] Each clinically available TARE microsphere may have unique limitations due to itsphysical properties and selected radionuclide production process, respectively. For example, QuiremSpheres®may be prone to damage within nuclear reactors, limiting both the number of facilities that can produce the166Ho, and the quantity of166Ho that can be generated in a single patient dose. The achievable specific activity (Bq / gram or Bq / microsphere) for QuiremSpheres®may be limited by heat- and radiation-induced damage to the organic polymer PLLA that occurs during neutron bombardment to generate the therapeutic166Ho. This specific activity for QuiremSpheres®may be lower than the specific activity attainable in TheraSphere®. The lower specific activity combined with the shorter half-life of166Ho compared to90Y may hinder dosimetric flexibility and limits the geographical area over which the microspheres can be distributed, as the treatment typically must be administered to the patient within 24-60 hours of end of neutron bombardment in a nuclear reactor.WSGR Docket No.66410-701601

[0050] Unlike QuiremSpheres® and TheraSphere®, the therapeutic radionuclide in SIR-Spheres may not be generated in situ via neutron activation; instead, SIR-Spheres may be produced by radiolabeling a polymer substrate with90Y obtained from a90Sr / 90Y radionuclide generator. Due to the nature of the labeling process, a limited amount of90Y can be loaded onto the surface of each microsphere, resulting in very low specific activity microspheres (~50 Bq / sphere). This may limit their clinical use, as a much larger number of microspheres may be required to impart the same radiation dose compared to TheraSphere®. In consequence, SIR- Spheres may be limited to treating patients who require low therapeutic doses (Gy / kg) of radiation, rather than the full spectrum of individuals with hepatic malignancies.

[0051] Glass microspheres may be a good carrier for radionuclides. For example, analuminosilicate glass matrix may be resistant to thermal and radiation-induced damage, enabling it to withstand neutron bombardment in a high flux environment. This in turn enables microspheres to reach higher specific activities (~2,500 Bq / sphere), with no significant post- suspension degradation en route to the clinic. Using microspheres with higher specific activity may create a larger utilization window (i.e. shelf-life) compared to the lower specific activity microspheres SIR-Spheres and QuiremSpheres®. The higher specific activity may also provide clinicians with more flexibility in dosimetry and mass of material administered, allowing them to fine-tune the treatment to individual patient needs. A key limitation of TheraSphere®may be the poor neutron activation cross-section of the89Y(n,γ)90Y nuclear reaction (σth = 1.28 b) which may necessitate use of a high flux nuclear reactor and relatively long neutron bombardment times (5-10 days) to achieve therapeutic quantities of the radionuclide90Y. This may limit the number of facilities worldwide that are capable of supporting TheraSphere®activation to approximately a dozen sites, rendering the supply chain vulnerable while increasing the costs of production.

[0052] A combination of microspheres having different half-lives and / or different energiescan be desirable and beneficial. Firstly, the advantage of having isotopes with extremely short half-lives (e.g., no more than a day or two) may permit the inclusion of elements that may provide CT contrast but may have decayed substantially by the time of administration, thereby allowing for personalized dosimetry. Secondly, another variation is to provide microspheres containing combined isotopes with variable therapeutic half-lives to further allow optimization of procedures. Thirdly, providing a combination of microspheres with variable energies allows treatments to be tailored specifically to different tumor types, sizes, and locations. This tunability of the disclosed microspheres make them a better choice for personalized dosimetry.WSGR Docket No.66410-701601 The need for theranostics

[0053] TARE has traditionally served as a palliative treatment; however, an increasingprevalence of cancer, an increasing demand for minimally invasive treatment options, as well as recent strides in patient-specific dosimetry models and software have raised a demand for its use as a curative treatment therapy across all stages of disease. These “personalized medicine” approaches may facilitate individualized treatment plans tailored to each patient and their unique anatomical measurements and treatment goals. This enhanced precision may enable the administration of maximum tolerable radiation doses (maximum threshold dosimetry) to the tumor while limiting exposure to the surrounding healthy tissue, resulting in improved tumor response and patient outcomes. However, a shift towards personalized dosimetry demands a high level of accuracy in both treatment planning and in microsphere administration. This can be achieved if the biodistribution of the microspheres can be monitored precisely and accurately during administration to the patient.

[0054] The treatment planning procedure can occur 1-3 weeks prior to the treatment andinvolves the use of an imageable diagnostic surrogate particle, or scout dose, to simulate the treatment. This pre-treatment procedure can be a crucial step in assessing both intra- and extrahepatic microsphere distribution, identifying contraindications for treatment, confirming patient eligibility, and planning the prescribed activity for the subsequent treatment. Traditionally in TARE, treatment planning has been conducted using technetium-99m labelled macroaggregated albumin (99mTc-MAA). The radionuclide99mTc (t½= 6.0 h; Eγ= 140 keV, 89%) is considered the gold standard for SPECT imaging, with more than 40 million diagnostic procedures conducted worldwide every year due to its low cost, near-ideal nuclear properties, and short half-life, which allows sufficient time for radiopharmaceutical production and imaging without imparting unnecessary radiation dose to the patient.99mTc-MAA is a biodegradable radiotracer comprised of macroaggregated albumin particles intended for use as a diagnostic tool for evaluating pulmonary regional perfusion; however, it is also used off-label as a scout dose for patients prior to TARE, enabling visualization of the intra- and extrahepatic particle distribution.99mTc-MAA particles have a density of 1.1 g / mL and a broad size range of 10-150 μm, with more than 90% of particles falling within 20-70 μm and a mean particle size of approximately 20-40μm. Typically,99mTc-MAA is administered in a dose of approximately 350,000 particles, although this can vary anywhere from 200,000 to 700,000 particles depending on the treatment case. See, A. S. Pasciak et al., “Treatment planning part II: Procedure simulation and prognostication,” Handb. Radioembolization, no.11822, pp.53–61, 2016. Synergy Spheres II may permit same-day on-table workup, treatment, intra-procedural feedback, and post-procedural feedback on distribution and dosing.WSGR Docket No.66410-701601

[0055] When comparing the properties of 99mTc-MAA diagnostic / scout dose to thetherapeutic microspheres used in TARE, it is evident that despite having a similar mean particle size to the therapeutic microspheres,99mTc-MAA has a different overall particle size range, density, and number of particles administered, rendering it a non-ideal surrogate for treatment planning. For example,99mTc-MAA has been shown to overestimate lung shunting, thereby resulting in erroneous curtailment of prescribed activity to some patients, while excluding others who would benefit from access to this therapy. As such, there is an opportunity for the development of new scout doses capable of providing a more accurate and precise depiction of therapeutic microsphere distribution, a pre-requisite for effective personalized treatment plans.

[0056] 99mTc-MAA was the primary surrogate particle used in TARE until recently, whenthe166Ho product QuiremSpheres®received European regulatory approval in 2015. QuiremSpheres®was the first TARE device designed for accurate treatment planning, as the therapeutic radionuclide166Ho has a low-intensity photon (Eγ= 80.6 keV, 6.56%) that enables imaging of the microspheres using a standard SPECT camera. The introduction of QuiremSpheres®was accompanied by QuiremScout®, a new166Ho scout dose, which is simply a smaller dose (250 MBq) of the166Ho therapeutic microspheres. Thus, in166Ho TARE, the microspheres used for both treatment planning and therapy are identical aside from the number of microspheres administered and their specific activity. The166Ho microspheres have a particle size distribution of 15-60 μm (mean diameter of 30 μm), and a density of 1.4 g / mL, such that the approximate number of microspheres administered per GBq is 10 × 106. Accordingly, there are approximately 2.5 × 106microspheres administered in a 250 MBq dose of QuiremScout®, whereas the number of microspheres delivered for treatment varies depending on the desired absorbed dose to the tumor. Although SPECT images obtained from166Ho exhibit inferior spatial resolution, sensitivity, and contrast recovery compared to99mTc scans, the 250 MBq dose of QuiremScout®microspheres may permit imaging of microsphere biodistribution. Additionally,166Ho microspheres can be visualized on magnetic resonance imaging (MRI) due to the highly paramagnetic nature of holmium. The improved dosimetric accuracy that arises from using the same microspheres for simulation and treatment can support more accurate patient screening and increased clinical benefit for patients. For instance, with a true representation of therapeutic microsphere biodistribution, clinicians can be more aggressive with their treatment plans, delivering maximum tolerable doses to the tumor with an enhanced confidence that surrounding tissue will not be harmed. The congruence between scout and therapeutic microspheres is valuable in promoting the use of166Ho TARE; however, QuiremSpheres®are limited by the production challenges described earlier.WSGR Docket No.66410-701601

[0057] The quantitative imaging of TheraSphere® and SIR-Sphere® using conventionalimaging techniques is non-trivial. Neither TheraSphere®nor SIR-Spheres®is visible using MRI or CT imaging, as they do not contain paramagnetic components or components with sufficient electron density to create X-ray contrast, respectively. Moreover, unlike166Ho,90Y decays without emitting gamma photons suitable for imaging by SPECT. Nonetheless, it emits high energy beta particles that generate a broad and continuous spectrum of secondary X-ray photons called bremsstrahlung, which can be imaged on SPECT systems. However, due to the continuous energy spectrum and lack of a distinct photopeak, bremsstrahlung SPECT imaging may pose a challenge. Alternatively, a small fraction of the90Y decay results in positron emissions (via pair production) that can be reconstructed by PET detectors, but the low positron yield (1 per 0.003% of disintegrations, ~32 ppm) complicates quantification especially in the presence of high-energy bremsstrahlung emissions. Although advancements in PET scanners over the recent years (e.g., adopting time-of-flight (TOF) algorithms, hardware, and image reconstruction software developments) may have made post-treatment90Y dosimetry and treatment verification technically possible, the very low count rate may make images prone to deterioration by Poisson noise and accurate detection of small activity levels difficult.

[0058] A new paradigm for TARE microsphere technology may suggest the development of166Ho microspheres in theranostics. A radioactive nuclide may have the innate capability to act as both a diagnostic marker (scout dose) and a therapeutic agent (treatment dose). The theranostics approach in the nuclear medicine field may contribute to individualized treatment, enhanced patient selection, improved prediction of response and toxicity, and eliminate costs associated with unnecessary diagnostic examinations. These advances in TARE may exhibit both the potential clinical utility and benefit to patients of a fully imageable radioactive microsphere, and the need for a new generation of imageable TARE therapeutics that are specifically designed to meet clinician needs.

[0059] At present, therapeutic TARE microspheres (i.e. radioactive microspheres) can beimaged by PET, SPECT, and MRI, none of which is the ideal imaging modality for TARE treatment planning and administration. While SPECT has high sensitivity capable of detecting levels of radioactivity that exceed background levels by as little as 2.4- to 1-fold, it also has low resolution and lacks anatomical information compared to alternative imaging techniques such as CT or MRI. Additionally, because SPECT scan acquisition times are typically in the order of 10- 30 minutes, respiratory motion throughout the scan has been reported to result in artifacts and misregistration of activity around the diaphragm. Alternatively, MRI has remarkable soft tissue contrast and, at high levels of high temporal and spatial resolution, provides detailed functional and anatomical information. Since MRI relies on differences in susceptibility rather thanWSGR Docket No.66410-701601 radioactivity, it can be used to image the biodistribution of decayed microspheres well beyond the time of therapy, unlike SPECT imaging. However, susceptibility artifacts in MRI, particularly around air-containing organs like the lungs and intestines, hinder dose assessment. Furthermore, MRI and PET do not permit intraoperative dosimetry due to long acquisition times and because these scanners are not typically available in-room. Thus, to acquire an interoperative PET or MR image, the patient must be transported to an imaging suite during administration of the radioactive microspheres, which is far from ideal.

[0060] To optimize accuracy and precision in TARE, further advances in microsphereimaging are desired. For example, real-time tracking of the microsphere administration during both the treatment planning and therapeutic procedures would give the clinician direct and actionable feedback, increased control over the procedure for immediate adjustment of treatment parameters and confirmation of microsphere delivery to optimize and verify dosimetry. Furthermore, real-time imaging would provide the opportunity to combine the scout and therapeutic dose in one single out-patient procedure, resulting in less stress to patients and cost- savings for the healthcare system. Currently, none of the particles used in TARE are imaged in real-time during administration because the scan durations for nuclear imaging and MRI are typically in the order of 15-30 minutes. Although the localized and concentrated deposition of activity characteristic of TARE procedures may permit good quality images after only 5-10 minutes, imaging during treatment would still require a planar scintigraphy, SPECT, SPECT / CT, PET, or MRI scanner to be available in the interventional radiology (IR) suite. This may not be ideal due to the inconvenience of additional bulky equipment in the IR suite, the cost associated with dedicated SPECT, PET, or MRI scanners solely for the IR suite, and potentially limited access to shared equipment used outside the IR suite. As such, having a microsphere that can be visualized using intra-procedural angiography or x-ray fluoroscopy, CT, or cone beam computed tomography (CBCT) would be of extreme value, as this imaging equipment is readily available in the IR suite.

[0061] Locoregional oncology therapies based on transarterial embolization (TAE) typicallydeliver microspheres into targeted tissues via microcatheter. At present, and to enhance patient outcomes, microsphere technologies are progressively being engineered to deliver therapeutic doses of localized radiation or chemotherapeutics. To ensure that the therapeutic agent is delivered to the correct site, TAE procedures are performed using a range of x-ray based imaging techniques, including fluoroscopy, digital subtraction angiography, computed tomography (CT) and cone-beam CT (CBCT). Notably however, most microspheres that are presently available to physicians are radiolucent in nature. This is an intrinsic limitation of existing technologies which (i) limits the acquisition of critical intraprocedural feedback and (ii)WSGR Docket No.66410-701601 curtails the full potential of post-procedural imaging assessments. Providing imageable microspheres would deliver valuable knowledge relating to the procedure which may standardize and optimize treatment approaches, and most crucially provide dose distribution (i.e., dosimetry) information personalized to the individual patient.

[0062] Silicate glass-based microspheres can readily incorporate significant concentrationsof high atomic number elements with variable k-edges into contiguous glass networks while reducing ionic leaching, thus ameliorating toxicological risk while providing a means to maximize radiopacity. Additionally, silicate glass-based microspheres can exhibit high thermal and radiolytic stability: this is essential particularly for transarterial radioembolization (TARE) agents, where a therapeutic radionuclide (e.g., Y-90, Ho-166) is required to be generated in situ via neutron activation in a nuclear reactor core. The harsh environment within the neutron flux of a nuclear reactor features high temperatures and levels of ionizing radiation that readily destroy covalent bonds. This can cause melting, flaking, and cracking of organic polymers. This in turn limits the effective specific activity (Bq / g) that can be achieved in the polymeric microspheres, which results in logistical challenges (e.g., rapid ship times are required) and limits the radiation dose that can be delivered in a set treatment volume.

[0063] In comparison to organic polymers, neutron bombardment conditions are generallybetter tolerated by inorganic glasses due to their higher melting points and absence of covalent bonding. These materials can therefore be subjected to longer neutron bombardments at higher neutron fluxes, enabling maximization of the radioactivity per microsphere. Glasses developed for TARE applications must still be carefully assessed for metal leaching both before and after neutron bombardment, as interactions do occur between the microsphere surfaces and aqueous suspension media including adsorption, hydration and ion exchange that may lead to leaching of metal ions in vivo. Any damage the glass sustains during neutron activation may amplify these interactions, exacerbating leakage of metals from the microspheres. Mobilization of metal ions must be assessed both from a standard toxicological perspective, and from and radiological standpoint, as migration of radioactive material within the body can cause damage to non-target tissues. Radioactive Materials

[0064] In addition to the two radionuclides currently used for TARE (Y-90, Ho-166), thereare several other beta emitting radionuclides that may demonstrate therapeutic abilities. For example, lutetium-177 is already approved by the US FDA and other regulatory bodies for clinical use in two different chemical forms: Lutathera (neuroendocrine tumors) and Pluvicto (prostate cancer), and is under investigation for treating a wide range of other malignancies. Several chelated forms of samarium-153 may treat bone metastases from common primaryWSGR Docket No.66410-701601 tumors; Sm-153 may be used clinically. Rhenium-188 may be used as the cancer therapy Rhenium-SCT (non-melanoma skin cancer) and may be used as the active component in radiopharmaceuticals.

[0065] Radiopharmaceuticals containing rhenium-186 may be used in clinical studies.Dysprosium-166 (t½ = 81.6 h) is a short-range therapeutic itself (Eβmax = 0.399 MeV) but may decay spontaneously to Ho-166; it may be used to increase the effective half-life of Ho-166 in targeted and colloidal radiopharmaceuticals. Terbium-161 may display similar nuclear properties to Lu-177 with additional emission of Auger electrons which may impart additional therapeutic efficacy. Radionuclides of praseodymium (Pr-142, 143), promethium-149, and rhodium-105 may demonstrate therapeutic ability in preclinical studies.

[0066] The radionuclide may be administered in a pharmaceutically acceptable form. Theform may also be capable of remaining at the site of application for a controlled length of time, in combination with a means for control of local delivery. For example, the radionuclide could be in the form of an element, an inorganic compound, or an organic compound. Radioactive and imageable microspheres

[0067] The present disclosure presents a non-degradable microspherical matrix comprisingone or more radionuclides. The radionuclides include but are not limited to: Y, Ho, Rh, Pr, Lu, Pm, Sm, Tb, Dy, Re, and Au. The microspherical matrix may have multi-modal imaging capabilities.

[0068] In some embodiments, the next generation of TARE microspheres (“SynergySpheres”) may possess a unique and powerful set of advantages in the field of TARE as shown in any or combination of the following attributes:

[0069] (1) Synergy Spheres may be microspheres (including glass microspheres and glass-ceramic microspheres) comprising a mixture of element oxides, including but not limited to: silicon dioxide, aluminum oxide, yttrium oxide, and holmium oxide. These element oxides may be physically robust, stable to temperatures ≥ 500 ºC, and may not exhibit substantial damage (as used herein, the term “substantial damage,” generally refers to more than 5%, preferably more than 2%,, and more preferably more than 1% activity leaching over the duration of one half-life) after exposure to high flux neutron irradiation conditions (as used herein, the term “high flux,” generally refers to φ ≥ 1 × 1014n / cm2•s for a duration of t ≥ 24 h) in a nuclear research reactor. Synergy Spheres may be the first glass theranostic microspheres (including the first glass TARE microspheres) to contain chemical elements other than silicon, aluminum, yttrium, and oxygen.

[0070] (2) Synergy Spheres may be the first microsphere family designed to enable fullypersonalized TARE treatments by making a plurality of different therapeutic radionuclidesWSGR Docket No.66410-701601 available to clinicians. Synergy Spheres may be the first microspheres to contain dual-isotopes. Providing variable ratios of two radioactive isotopes, such as yttrium-90 and holmium-166, may provide flexibility in the type of radiation present, the half-life, the tissue penetration depth, the specific activity per microsphere, and the imaging capabilities of the microspheres. For example, the industry standard Y-90 has a maximum beta energy of 2.28 MeV (Eβavg = 933.7 MeV) resulting in a maximum range in tissue of 11 mm (ravg = 2.5 mm). In comparison, Ho-166 has slightly lower beta energies (Eβmax= 1.773 MeV, 1.855 MeV; Eβavg= 651 keV, 694 keV), resulting in greater localization of the therapeutic effect (rmax= 8.7 mm; ravg= 2.2 mm). Synergy Spheres may provide optimal dosimetric flexibility to clinicians, enabling treatment of smaller lesions with less damage to healthy tissue. Synergy Spheres can be formulated in variable compositions, providing a portfolio of treatment options to users, with specific activities varying from 50-5000 Bq / sphere. This flexibility may provide the options to vary beta radiation payload and the number of microspheres delivered, giving clinicians more freedom to choose the most appropriate dose for the specific patient and their treatment needs.

[0071] (3) Synergy Spheres may offer multi-modal imaging capabilities. They can beimaged by CT and CBCT, which may permit real-time imaging and intraoperative dosimetry as CT is the imaging modality already present in the IR suites where TARE administration takes place. This feature may provide clinicians with a real-time feedback on microsphere biodistribution during administration, enabling the medical professionals to make informed decisions and adjust the treatment plan as necessary, ensuring accurate and optimal radiation delivery. Real-time imaging may also provide the opportunity to combine the scout and therapeutic dose in one single out-patient procedure, saving on costs and reducing patient stress. Certain Synergy Spheres formulations may also be imageable using other standard clinical modalities, such as, for example, MRI, ultrasound, and SPECT.

[0072] (4) Synergy Spheres may be theranostic microspheres with the capability to act as adiagnostic tool and a therapeutic agent at the same time and / or in the same or similar configuration in terms of chemical composition and physical attributes (except for the radiation intension and capacity). Since Synergy Spheres can be generated in a range of specific activities (~50-2500 Bq / sphere), they can provide both high-activity low-volume doses for patients requiring large doses of radiation, as well as low-activity microspheres to be used in pre- treatment planning. The use of identical or substantially identical microspheres for treatment planning and therapy may ensure the most accurate representations of the therapeutic microspheres. By employing advanced targeting techniques and customized dosimetry models, selective delivery of the maximum tolerable radiation dose to the tumor may be accomplished,WSGR Docket No.66410-701601 while minimizing the impact on healthy parenchyma. This may ensure effective tumor control while reducing potential complications for patients.

[0073] The silicate glasses can be synthesized and characterized with respect to their safety,physical and chemical properties, and performance as potential radioembolic microspheres (i.e., particle size distribution, crystallinity, density, glass transition temperature (Tg), surface morphology, x-ray imageability, chemical composition, radioisotope emissions, cytotoxicity). Based on these parameters, the individual and interaction effects of glass constituent(s) on density, x-ray imageability, and glass transition temperature can be studied, optimized, and relied upon to improve therapeutic effect. For example, the data collected can help evaluate an optimal glass composition that ensures no cytotoxic response in simulated physiological conditions, and which can (i) maximize radiopacity and (ii) maximize thermal stability. After the identification of a lead candidate microsphere formulation, the risks associated with potential leaching of metallic ions and radioisotopes upon interaction with aqueous media can be evaluated by conducting leaching studies pre- and post-irradiation. Synergy Spheres

[0074] As disclosed here, there are different compositions for Synergy Spheres. Forexample, some non-exclusive compositions of Synergy Spheres include the following three designs from which multiple products can be made:

[0075] (1) 166Ho based therapeutic microsphere or theranostic microsphere with the majorityof beta emissions arising from holmium-166, optionally with the potential inclusion of alternative radionuclides in the same matrix;

[0076] (2) 90Y based therapeutic microsphere or theranostic microsphere with the majorityof beta emissions arising from yttrium-90, optionally with the potential inclusion of alternative radionuclides in the same matrix; and

[0077] (3) A portfolio of therapeutics or theranostics based on an alternative radionuclideswith the inclusion of one or more of the radionuclides from the following list: Y, Ho, Rh, Pr, Lu, Pm, Sm, Tb, Dy, Re, Au, in addition to the choices (1) and (2) listed above.

[0078] Compositions of the microsphere

[0079] In an aspect, the microsphere comprises: from about 0.50 to about 0.90 mole fractionof silicon dioxide; from about 0.05 to about 0.30 mole fraction of aluminum oxide; and from about 0.001 to about 0.25 mole fraction of holmium oxide.

[0080] In some embodiments, the microsphere comprises: from about 0.60 to about 0.80mole fraction of silicon dioxide; from about 0.10 to about 0.25 mole fraction of aluminum oxide; and from about 0.001 to about 0.20 mole fraction of holmium oxide.WSGR Docket No.66410-701601

[0081] In some embodiments, the microsphere comprises: from about 0.65 to about 0.75mole fraction of silicon dioxide; from about 0.14 to about 0.25 mole fraction of aluminum oxide; and from about 0.001 to about 0.15 mole fraction of holmium oxide.

[0082] In some embodiments, the microsphere comprises: from about 0.65 to about 0.74mole fraction of silicon dioxide; from about 0.14 to about 0.19 mole fraction of aluminum oxide; and from about 0.001 to about 0.12 mole fraction of holmium oxide.

[0083] In some embodiments, the microsphere comprises from about 0.001 to about 0.25mole fraction of holmium oxide, e.g., about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, or 0.25 mole fraction of holmium oxide.

[0084] In some embodiments, the microsphere comprises from about 0.001 to about 0.25mole fraction of holmium oxide, e.g., from about 0.001 to about 0.005, from about 0.005 to about 0.009, from about 0.008 to about 0.01, from about 0.01 to about 0.03, from about 0.03 to about 0.04, from about 0.04 to about 0.05, from about 0.05 to about 0.09, from about 0.09 to about 0.11, from about 0.11 to about 0.12, from about 0.12 to about 0.13, from about 0.13 to about 0.14, or from about 0.14 to about 0.15, from about 0.15 to about 0.16, from about 0.16 to about 0.17, from about 0.17 to about 0.18, or from about 0.18 to about 0.19, from about 0.19 to about 0.20, from about 0.20 to about 0.21, from about 0.21 to about 0.22, from about 0.22 to about 0.23, from about 0.23 to about 0.24, or from about 0.24 to about 0.25 mole fraction of holmium oxide.

[0085] In some embodiments, the microsphere further comprises yttrium. In someembodiments, the microsphere further comprises yttrium oxide. In some embodiments, the microsphere further comprises from about 0.001 to about 0.15 mole fraction of yttrium oxide.

[0086] In some embodiments, the microsphere further comprises from about 0.001 to about0.15 mole fraction of yttrium oxide, e.g., about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide.

[0087] In some embodiments, the microsphere comprises from about 0.001 to about 0.15mole fraction of yttrium oxide, e.g., from about 0.001 to about 0.005, from about 0.005 to about 0.009, from about 0.008 to about 0.01, from about 0.01 to about 0.03, from about 0.03 to about 0.04, from about 0.04 to about 0.05, from about 0.05 to about 0.09, from about 0.09 to about 0.11, from about 0.11 to about 0.12, from about 0.12 to about 0.13, from about 0.13 to about 0.14, or from about 0.14 to about 0.15 mole fraction of yttrium oxide.

[0088] In some embodiments, the microsphere comprises any combination of (i) the molefraction of holmium oxide disclosed above and (ii) the mole fraction of yttrium oxide disclosedWSGR Docket No.66410-701601 above, including both the mole fractions and the range of mole fractions for holmium oxide and yttrium oxide, respectively.

[0089] In some embodiments, the microsphere comprises about 0.001 mole fraction ofholmium oxide and about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide.

[0090] In some embodiments, the microsphere comprises about 0.002 mole fraction ofholmium oxide and about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide.

[0091] In some embodiments, the microsphere comprises about 0.003 mole fraction ofholmium oxide and about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide.

[0092] In some embodiments, the microsphere comprises about 0.004 mole fraction ofholmium oxide and about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide.

[0093] In some embodiments, the microsphere comprises about 0.005 mole fraction ofholmium oxide and about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide.

[0094] In some embodiments, the microsphere comprises about 0.006 mole fraction ofholmium oxide and about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide.

[0095] In some embodiments, the microsphere comprises about 0.007 mole fraction ofholmium oxide and about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide.

[0096] In some embodiments, the microsphere comprises about 0.008 mole fraction ofholmium oxide and about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide.WSGR Docket No.66410-701601

[0097] In some embodiments, the microsphere comprises about 0.009 mole fraction ofholmium oxide and about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide.

[0098] In some embodiments, the microsphere comprises about 0.01 mole fraction ofholmium oxide and about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide.

[0099] In some embodiments, the microsphere comprises about 0.02 mole fraction ofholmium oxide3and about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide.

[0100] In some embodiments, the microsphere comprises about 0.03 mole fraction ofholmium oxide and about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide.

[0101] In some embodiments, the microsphere comprises about 0.04 mole fraction ofholmium oxide and about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide.

[0102] In some embodiments, the microsphere comprises about 0.05 mole fraction ofholmium oxide and about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide.

[0103] In some embodiments, the microsphere comprises about 0.06 mole fraction ofholmium oxide and about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide.

[0104] In some embodiments, the microsphere comprises about 0.07 mole fraction ofholmium oxide and about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide.

[0105] In some embodiments, the microsphere comprises about 0.08 mole fraction ofholmium oxide and about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01,WSGR Docket No.66410-701601 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide

[0106] In some embodiments, the microsphere comprises about 0.09 mole fraction ofholmium oxide and about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide.

[0107] In some embodiments, the microsphere comprises about 0.1 mole fraction ofholmium oxide and about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide.

[0108] In some embodiments, the microsphere comprises about 0.11 mole fraction ofholmium oxide and about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide.

[0109] In some embodiments, the microsphere comprises about 0.12 mole fraction ofholmium oxide and about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide.

[0110] In some embodiments, the microsphere comprises about 0.13 mole fraction ofholmium oxide and about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide.

[0111] In some embodiments, the microsphere comprises about 0.14 mole fraction ofholmium oxide and about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide.

[0112] In some embodiments, the microsphere comprises about 0.15 mole fraction ofholmium oxide and about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide.

[0113] In some embodiments, the microsphere comprises about 0.16 mole fraction ofholmium oxide and about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide.WSGR Docket No.66410-701601

[0114] In some embodiments, the microsphere comprises about 0.17 mole fraction ofholmium oxide and about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide.

[0115] In some embodiments, the microsphere comprises about 0.18 mole fraction ofholmium oxide and about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide.

[0116] In some embodiments, the microsphere comprises about 0.19 mole fraction ofholmium oxide and about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide.

[0117] In some embodiments, the microsphere comprises about 0.20 mole fraction ofholmium oxide and about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide.

[0118] In some embodiments, the microsphere comprises about 0.21 mole fraction ofholmium oxide and about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide.

[0119] In some embodiments, the microsphere comprises about 0.22 mole fraction ofholmium oxide and about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide.

[0120] In some embodiments, the microsphere comprises about 0.23 mole fraction ofholmium oxide and about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide.

[0121] In some embodiments, the microsphere comprises about 0.24 mole fraction ofholmium oxide and about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide.

[0122] In some embodiments, the microsphere comprises about 0.25 mole fraction ofholmium oxide and about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01,WSGR Docket No.66410-701601 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15 mole fraction of yttrium oxide.

[0123] In some embodiments, the microsphere disclosed above further comprise anotherradionuclide or a metal oxides that can become radioactive other than holmium, or other than holmium and yttrium. In some embodiments, the majority of beta emissions from the microsphere disclosed above are arising from yttrium-90. In some embodiments, the majority of beta emissions from the microsphere disclosed above are arising from holmium-166. In some embodiments, the microspheres is a combination of the microsphere disclosed above, i.e., including microspheres of having two or more different compositions.

[0124] In some embodiments, the microsphere disclosed above comprises at least oneradionuclide or a metal oxide that can become radioactive, wherein at least one radionuclide or metal oxides is imageable.

[0125] Particle sizes

[0126] In some embodiments, the microsphere disclosed above has an average diameterfrom about 5 μm to about 4500 μm. In some embodiments, the microsphere has an average diameter from about 5 μm to about 4000 μm, from about 5 μm to about 3000 μm, from about 5 μm to about 2000 μm, from about 5 μm to about 1500 μm, from about 5 μm to about 1300 μm, from about 5 μm to about 1200 μm, from about 5 μm to about 30 μm, from about 10 μm to about 35 μm; from about 10 μm to about 45 μm; from about 20 μm to about 30 μm; from about 20 μm to about 40 μm; from about 20 μm to about 50 μm; from about 40 μm to about 500 μm; from about 40 μm to about 300 μm; from about 300 μm to about 500 μm; from about 500 μm to about 700 μm; from about 700 μm to about 1200 μm, from about 1200 μm to about 1500 μm, from about 1500 μm to about 2000 μm, from about 2000 μm to about 2500 μm, from about 2500 μm to about 3000 μm, from about 3000 μm to about 3500 μm, from about 3500 μm to about 4000 μm, or from about 4000 μm to about 4500 μm. The ranges described herein include all endpoints and sub-ranges between the end points, and all integer values between the endpoints. In some embodiments, the individual particles of the microspheres are, e.g., about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 85, 90, 95, or 100 μm in diameter. In some embodiments, the particle size comprises: D0=15 μm; D50=25 μm, D95=35 μm. In some embodiments, the particle size comprises: D0=25 μm; D50=35 μm, D95=45 μm. In some embodiments, the particle size comprises: D0=35 μm; D50=45 μm, D95=55 μm. In some embodiments, the particle size comprises: D0=45 μm; D50=55 μm, D95=65 μm. TheWSGR Docket No.66410-701601 particle size can be determined using methods, for example, laser diffraction according to ISO13320 standard (2009).

[0127] Radiopacity

[0128] The microspheres described herein have a radiopacity sufficient to visualize theparticulate materials (e.g., beads or bubble or microspheres) during in vivo delivery of the particulate materials to a human or animal subject. In some embodiments, the radiopacity is determined by cone-beam and conventional CT evaluation (see S. Kehoe et al., Effects of γ- irradiation and accelerated aging on composition-structure-property relationships for radiopaque embolic microspheres. Journal of Non-Crystalline Solids 402, 2014, 84-90). In some embodiments, the average CT radiopacity is from about 9,000 to about 20,000 Hounsfield Units (HU) at an energy of 70 kVp, and the average CT radiopacity is from about 5,000 to about 19,000 HU at an energy of 120 kVp.

[0129] Irradiated compositions

[0130] The compositions of microspheres described herein can produce radioisotopes whenirradiated with neutrons. Neutron activation is a consistent and highly predictable phenomenon. The quantity of radioisotope produced upon irradiation on the microspheres disclosed herein in a neutron flux can be accurately predicted or estimated using the equation shown below. The number of atoms N is determined by the sample mass; the neutron flux φ and irradiation time t are selected by the nuclear scientist; the neutron absorbance cross-section σ is a fixed value that is unique to each stable isotope; the decay constant λ is a physical property of the radioisotope being formed. A=Nφσ(1−e-λt) A=a^ ctivity produced ^ N=number of atoms ^ φ=neutron flux ^ σ=neutron capture cross-section ^ λ=decay constant ^ t=irradiation time

[0131] For clarity, radioisotope scientists generally differentiate between radionuclidicimpurities - radioisotopes that form unexpectedly due to impurities in the sample - and incidental activation products, which are radioisotopes other than the desired species that are expected to form due to the sample composition. Radionuclidic impurities can be minimized (or eliminated) by careful preparation of the sample material, use of high purity reagents, and so on.WSGR Docket No.66410-701601 Neutron Activation Analysis (NAA) can be used to determine whether there are any impurities in the compositions described herein. As disclosed below, impurities, such as certain elements, are to be excluded or to be kept at a threshold level.

[0132] Glass microspheres comprising Holmium, a high atomic number element with afavorable k-edge, may enhance CT imageability. The substitution of yttrium with holmium at varying concentrations in glass microspheres may allow for the investigation of compositional effects on key material properties, including density, Tg, and CT imageability. Numerated Embodiments

[0133] Embodiment 1. A microsphere, comprising:(i) an aluminosilicate; and(ii) one or more radionuclides,wherein the microsphere is radioactive, and wherein the microsphere is imageable by computerized tomography (CT) or cone-beam computed tomography (CBCT).

[0134] Embodiment 2. The microsphere of Embodiment 1, wherein the one or moreradionuclides comprises holmium-166.

[0135] Embodiment 3. A microsphere, comprising:(i) an aluminosilicate; and(ii) one or more radionuclides comprising holmium-166,wherein the microsphere is radioactive.

[0136] Embodiment 4. The microsphere of Embodiment 3, wherein the microsphere isimageable.

[0137] Embodiment 5. A microsphere, comprising:(i) an aluminosilicate; and(ii) holmium oxide.

[0138] Embodiment 6. The microsphere of Embodiment 5, wherein the microsphere isimageable.

[0139] Embodiment 7. The microsphere of any one of Embodiments 3-6, wherein themicrosphere is imageable by computerized tomography (CT) or cone-beam computed tomography (CBCT).

[0140] Embodiment 8. The microsphere of any one of Embodiments 1-7, wherein themicrosphere comprises (a) holmium, and (b) at least another radionuclide.

[0141] Embodiment 9. The microsphere of Embodiment 8, wherein the microspherecomprises Ho-166, and optionally Y-90.

[0142] Embodiment 10. The microsphere of Embodiment 8 or Embodiment 9, wherein themicrosphere is imageable due to the presence of holmium and / or the at least one radionuclide.WSGR Docket No.66410-701601

[0143] Embodiment 11. The microsphere of any one of Embodiments 1-10, wherein themicrosphere is imageable by intra-procedural angiography, x-ray fluoroscopy, magnetic resonance imaging (MRI), ultrasound, positron emission tomography (PET), or single-photon emission computed tomography (SPECT), or a combination thereof.

[0144] Embodiment 12. The microsphere of any one of Embodiments 1-11, wherein themicrosphere comprises: (i) from about 0.50 to about 0.90 mole fraction of silicon dioxide;(ii) from about 0.05 to about 0.30 mole fraction of aluminum oxide; and(iii) from about 0.001 to about 0.25 mole fraction of holmium oxide.

[0145] Embodiment 13. The microsphere of Embodiment 12, wherein the microspherecomprises: (i) from about 0.60 to about 0.80 mole fraction of silicon dioxide;(ii) from about 0.10 to about 0.25 mole fraction of aluminum oxide; and(iii) from about 0.001 to about 0.20 mole fraction of holmium oxide.

[0146] Embodiment 14. The microsphere of Embodiment 12, wherein the microspherecomprises: (i) from about 0.65 to about 0.75 mole fraction of silicon dioxide;(ii) from about 0.14 to about 0.25 mole fraction of aluminum oxide; and(iii) from about 0.001 to about 0.15 mole fraction of holmium oxide.

[0147] Embodiment 15. The microsphere of Embodiment 12, wherein the microspherecomprises: (i) from about 0.60 to about 0.74 mole fraction of silicon dioxide;(ii) from about 0.14 to about 0.19 mole fraction of aluminum oxide; and(iii) from about 0.001 to about 0.12 mole fraction of holmium oxide.

[0148] Embodiment 16. The microsphere of any one of Embodiments 1-15, wherein themicrosphere further comprises yttrium.

[0149] Embodiment 17. The microsphere of any one of Embodiments 1-15, wherein themicrosphere further comprises yttrium oxide.

[0150] Embodiment 18. The microsphere of Embodiment 17, wherein the microspherefurther comprises from about 0.001 to about 0.15 mole fraction of yttrium oxide.

[0151] Embodiment 19. The microsphere of Embodiment 17, wherein the microspherefurther comprises from about 0.001 to about 0.14 mole fraction of yttrium oxide.

[0152] Embodiment 20. The microsphere of Embodiment 17, wherein the microspherefurther comprises from about 0.001 to about 0.12 mole fraction of yttrium oxide.WSGR Docket No.66410-701601

[0153] Embodiment 21. The microsphere of any one of Embodiments 1-20, wherein themicrosphere has an average diameter from about 5 μm to about 4500 μm.

[0154] Embodiment 22. The microsphere of Embodiment 21, wherein the microsphere hasan average diameter from about 5 μm to about 1300 μm, from about 5 μm to about 1200 μm, from about 5 μm to about 30 μm, from about 10 μm to about 35 μm, from about 10 μm to about 45 μm, from about 20 μm to about 30 μm, from about 20 μm to about 40 μm, from about 20 μm to about 50 μm, from about 40 μm to about 500 μm, from about 40 μm to about 300 μm, from about 300 μm to about 500 μm, from about 500 μm to about 700 μm, from about 700 μm to about 1200 μm, from about 1200 μm to about 1500 μm, from about 1500 μm to about 2000 μm, from about 2000 μm to about 2500 μm, from about 2500 μm to about 3000 μm, from about 3000 μm to about 3500 μm, from about 3500 μm to about 4000 μm, or from about 4000 μm to about 4500 μm.

[0155] Embodiment 23. The microsphere of any one of Embodiments 1-22, wherein themicrosphere remains durable following neutron irradiation with a high thermal neutron flux.

[0156] Embodiment 24. The microsphere of Embodiment 23, wherein the high thermalneutron flux is neutron irradiation conditions having φ no less than 5 × 1013n / cm2•s for a duration of time (t) no less than 24 h in a nuclear research reactor.

[0157] Embodiment 25. The microsphere of any one of Embodiments 1-24, wherein themicrosphere is adjustable in at least one property selected from the group consisting of ratio of different types of radiation, half-life, tissue penetration depth, specific activity per microsphere, and imaging capabilities.

[0158] Embodiment 26. The microsphere of Embodiment 25, wherein the at least oneproperty correlates to a ratio of holmium to the at least one radionuclide in the microsphere.

[0159] Embodiment 27. The microsphere of Embodiment 25 or Embodiment 26, whereinthe specific activity is from about 50 to about 5000 Bq / microsphere.

[0160] Embodiment 28. The microsphere of any one of Embodiments 1-27, wherein themicrosphere is a theranostic.

[0161] Embodiment 29. The microsphere of any one of Embodiments 1-27, wherein themicrosphere comprises a radionuclide that is imageable and emitting therapeutic radiation.

[0162] Embodiment 30. The microsphere of any one of Embodiments 1-29, wherein themicrosphere is glass.

[0163] Embodiment 31. A method comprising: administering to a subject, a plurality ofmicrospheres, wherein a microsphere of the plurality of microspheres is as in any one of Embodiments 1-30.WSGR Docket No.66410-701601

[0164] Embodiment 32. The method of Embodiment 31, further comprising: imaging at leasta section of the plurality of microspheres at or near an organ of the subject.

[0165] Embodiment 33. The method of Embodiment 32, the organ is a liver.

[0166] Embodiment 34. The method of Embodiment 32, the organ is anus, arteries,appendix, adrenal gland, brain, bones, bronchi, bladder, bone marrow, bulbourethral gland, colon, cervix, clitoris, cerebellum, diaphragm, ear, eye, fallopian tube, genital, gallbladder, heart, hypothalamus, interstitium, kidney, joint, lung, larynx, ligament, lymph node, large intestine, lymphatic vessel, mouth, mesentery, mammary glands, nose, nerve, nasal cavity, ovaries, esophagus, penis, pancreas, pharynx, placenta, prostate, pineal gland, pituitary gland, parathyroid gland, rectum, skin, spleen, scrotum, stomach, spinal cord, small intestine, salivary gland, skeletal muscles, seminal vesicles, subcutaneous tissue, testes, tendons, tongue, thyroid, trachea, thymus gland, ureters, urethra, uterus, vulva, veins, vagina, vas deferens, or vestigial organ.

[0167] Embodiment 35. The method of any one of Embodiments 32-34, wherein theimaging is computerized tomography (CT) imaging or cone-beam computed tomography (CBCT) imaging.

[0168] Embodiment 36. The method of any one of Embodiments 32-34, wherein theimaging is computerized tomography (CT) imaging, cone-beam computed tomography (CBCT) imaging, positron emission tomography (PET) imaging, radiographic imaging, intra-procedural angiography imaging, x-ray fluoroscopy imaging, magnetic resonance imaging (MRI) imaging, ultrasound imaging, or single-photon emission computed tomography (SPECT) imaging, or a combination thereof.

[0169] Embodiment 37. The method of any one of Embodiments 31-36, wherein theplurality of microspheres are radioactive.

[0170] Embodiment 38. The method of any one of Embodiments 31-37, wherein themicrosphere is a theranostic.

[0171] Embodiment 39. The method of any one of Embodiments 31-37, wherein themicrosphere provides radionuclide imaging and emits therapeutic radiation.

[0172] Embodiment 40. The method of any one of Embodiments 31-39, wherein themicrosphere is glass.

[0173] Embodiment 41. The method of any one of Embodiments 31-40, wherein theadministering is via intra-arterial or intravenous delivery.

[0174] Embodiment 42. A method comprising:(i) in a treatment planning step: administering to a subject, a first plurality ofmicrospheres; andWSGR Docket No.66410-701601 (ii) in a therapeutic treatment step: administering to the subject a second plurality ofmicrospheres, wherein a microsphere of the first plurality of microspheres and the second plurality of microspheres is as in any one of Embodiments 1-30.

[0175] Embodiment 43. The method of Embodiment 42, further comprising(a) in the treatment planning step: imaging at least a section of the first plurality of microspheres at or near an organ of the subject; and (b) in the therapeutic treatment step: imaging at least a section of the second plurality of microspheres at or near an organ of the subject.

[0176] Embodiment 44. The method of Embodiment 43, wherein the imaging in (a) and theimaging in (b) are in real-time.

[0177] Embodiment 45. The method of any one of Embodiments 42-44, wherein theimaging in (a) and the imaging in (b) are conducted in an interventional radiology (IR) suite in which the subject is being treated.

[0178] Embodiment 46. The method of any one of Embodiments 42-45, wherein the firstplurality of microspheres is substantially the same as the second plurality of microspheres in terms of chemical composition and / or physical characteristics.

[0179] Embodiment 47. The method of any one of Embodiments 42-46, the imaging in (a)and the imaging in (b) are computerized tomography (CT) imaging or cone-beam computed tomography (CBCT) imaging.

[0180] Embodiment 48. The method of any one of Embodiments 42-46, wherein theimaging in (a) and the imaging in (b) are computerized tomography (CT) imaging, cone-beam computed tomography (CBCT) imaging, positron emission tomography (PET) imaging, radiographic imaging, intra-procedural angiography imaging, x-ray fluoroscopy imaging, magnetic resonance imaging (MRI) imaging, ultrasound imaging, or single-photon emission computed tomography (SPECT) imaging, or a combination thereof.

[0181] Embodiment 49. The method of any one of Embodiments 42-48, wherein theadministering in (i) is via intra-arterial or intravenous delivery.

[0182] Embodiment 50. The method of any one of Embodiments 42-49, wherein theadministering in (ii) is via intra-arterial or intravenous delivery.

[0183] Embodiment 51. The method of any one of Embodiments 31-50, wherein the subjectis a human.

[0184] Embodiment 52. A method comprising (a) administering to a subject a microspherecomprising (i) alumina and silica, and (ii) one or more radionuclides, and (b) imaging a body of the subject to identify a location of the microsphere within the body of the subject.WSGR Docket No.66410-701601

[0185] Embodiment 53. The method of any one of Embodiments 42-52, wherein themicrosphere is a theranostic.

[0186] Embodiment 54. The method of Embodiment 52 or Embodiment 53, wherein themicrosphere provides radionuclide imaging and emits therapeutic radiation.

[0187] Embodiment 55. The method of any one of Embodiments 42-54, wherein themicrosphere is glass.

[0188] Certain examples of the following examples illustrate various methods of making themicrospheres or compositions thereof described herein. It is understood that one skilled in the art may be able to make these microspheres by similar methods or by combining other methods known to one skilled in the art. It is also understood that one skilled in the art would be able to make other microspheres in a similar manner as described below by using the appropriate starting materials and modifying synthetic routes as needed. In general, starting materials and reagents can be obtained from commercial vendors or synthesized according to sources known to those skilled in the art or prepared as described herein. EXAMPLES

[0189] Example 1: Microsphere Compositions Design

[0190] The design of Synergy Spheres compositions is based on a Design of Mixtures(DoM) statistical modelling approach. The DoM approach is employed to allow for unambiguous, systematic evaluations of the individual and interaction effects associated with various mixture components. This approach allows for the development of polynomial equations which indicate the relative influences of components on a given response (e.g., density, glass transition temperature, etc.), and ultimately support optimization of materials to a wide variety of properties via response surface regression methodologies. This form of predictive modelling stands in contrast to traditional trial and error style approaches for glass materials discovery and has the potential to accelerate the design of glass materials via simultaneous use of experimental methods and advanced modelling. Specifically, this disclosure is the first to employ the Design of Mixtures approach to produce quantitatively predictive models relating to the composition- structure-property-function relationships of aluminosilicate glasses modified with various therapeutic radionuclides.

[0191] Example 2: 66Ho therapeutic

[0192] The compositions for the starting materials for the glass microspheres are establishedusing Design-Expert Software (Version 13.0.15) from Stat-EaseTM. A design of mixtures of starting oxides I-optimal quadratic model is utilized based on four components (silicon dioxide, yttrium oxide, holmium oxide, and aluminum oxide). The design constraints based on mol% forWSGR Docket No.66410-701601 each component are provided in Table 2. Using these predefined constraints, this model yields a total of 16 glass formulations, as shown in Table 3, consisting of 10 model points, 3 lack of fit points, and 3 replicates. Replicate compositions are included to verify reproducibility in glass microsphere synthesis and characterization processes, and to increase the predictive power of the model. Table 2. Mixture of starting components and design constraint summary. Component Units Min MaxCodedCoded Hi h Mean Std DevTable 3. Glass compositions based on the mol% of each starting component. Replicate compositions denoted by asterisks. Glass No. SiO2 Y2O3 Ho2O3 Al2O3 *Glass compositions No.5 and No.16 are replicates. Glass compositions No.10 and No.13 are replicates. ***Glass compositions No.11 and No.14 are replicates.WSGR Docket No.66410-701601

[0193] Example 3: Glass Synthesis for DoM – Methods

[0194] Method A: Glasses were synthesized (MOSCI Corporation, Missouri, USA) via thetraditional melt quench technique. Succinctly, silicon dioxide (>99.9% purity), yttrium (III) oxide (99.99% purity), holmium (III) oxide (99.99% purity), and aluminum oxide (99.99% purity) reagents were weighed out in accordance with compositions listed in Table 3 and homogenized for about 1 hour prior to being transferred to platinum crucibles for melting. Glasses were melted in an electric furnace at temperatures ranging from about 1600 ºC to about 1700 ºC. Once the glasses were observed to be fully melted, they were stirred with a quartz rod and held at the melting temperature for about an additional 15 to 30 minutes dwell time to allow homogenization and release of air bubbles. The total melting time for the glasses (including the dwell time) ranged from about 45 minutes to about 110 minutes. Each melt was water quenched in distilled water and subsequently dried in the oven (at about 90 °C). The dried glass was then ball milled and sieved. Finally, the particles were subjected to flame spheroidization using a propane oxygen flame to transform the morphology of the glass particulate to a microsphere. After spheroidization, the microspheres were sieved for the <45 µm diameter size range. Fine particulate was separated from the resulting microspheres by floating in distilled water. The microspheres were then dried in the oven again (at about 65 °C). Glasses were stored in sealed high-density polyethylene (HDPE) containers and housed in vacuum desiccators for subsequent analysis.

[0195] Method B: Another way to make the glass microspheres are as follows. To fill thecrucibles higher and avoid bubbling over, the raw batch is split into multiple additions and each addition is then sequentially added over a time frame (the time frame can be varied, e.g., about every 30 minutes in up to a total of about 7 hours). This variation may allow volatilization of the water, carbonates, nitrates, and other ingredients, to occur slowly and may make more room as the batch melts down. After the final addition of all the additions, there is a holding time for fining and homogenization (e.g., about 1 h or longer) before pouring the contents from crucibles into distilled water. The rest of the steps are similar to Method A shown above.

[0196] Example 4: Glass Microsphere Characterization

[0197] Particle Size Analysis

[0198] A Malvern Mastersizer 3000 laser diffraction particle size analyzer is used as per themanufacturer’s instructions. Samples of each glass microsphere, in the <45 µm size range, are suspended in deionized water to obtain an obscuration value for the suspension from about 5% to about 8%. The glass suspension is then measured using both a blue (λ = 470 nm) and red (λ = 632.8 nm) laser. Each glass suspension is measured five times (n= 5), and particle sizeWSGR Docket No.66410-701601 distribution data are reported as the mean diameter Dx90, Dx50 and Dx10 (particle diameters at 90%, 50% and 10% cumulative size, respectively).

[0199] X-ray Diffraction (XRD)

[0200] XRD analysis is conducted utilizing a Malvern Panalytical Aeris XRD systemequipped with a PIXcel 1D detector. Samples of each glass microsphere are loaded into a hollow steel wafer and analyzed in the region between approximately 5° ≤ 2θ ≤ 60° with a step size of 2θ = 0.02 and a step time of 40 seconds.

[0201] Helium pycnometry

[0202] An AccuPyc 1340 helium pycnometer (Micromeritics, USA) equipped with a 1 cm3insert chamber is used to determine the density of each glass composition. From about 1.0 g to about 1.5 g of glass powder is used for each measurement, and each measurement comprises of about 10 fill and purge cycles (run in triplicates). The results are reported as the average ± standard deviation (SD) of three replicate measurements.

[0203] Differential Scanning Calorimetry

[0204] A simultaneous thermal analysis STA 449F5 Jupiter with Auto-Sampler (Netzsch-Geratebau-GMBH, USA) is used to analyze each glass composition. Approximately 30-60 mg of glass powder is weighed out, placed into Pt-Rh crucibles, and heated at 10 °C / min from 25 ºC to 1400 °C. Proteus Thermal Analysis software (Version 8.0.3) is used to determine the extrapolated onset (Tf), inflection (Ti), and end (Te) glass transition temperatures.

[0205] Radiopacity Evaluation (CT)

[0206] To evaluate for CT radiopacity, quantitative measurements are acquired by takingaxial CT scans of each sample through glass vials. Images are taken at about 70 kVp and about 120 kVp (400 mAs, a pitch of 0.5, and a 1 mm reconstructed slice thickness) using a clinical CT scanner (Somatom Definition AS+ (Siemens Healthineers, Erlangen, Germany)). The reported Hounsfield Unit (HU) values are determined from six distinct measurements and presented as mean ± standard deviation.

[0207] Scanning Electron Microscopy (SEM)

[0208] A sample of each glass composition is deposited onto a carbon tab adhered to analuminum SEM stub. Samples are coated with Gold / Palladium for 180 seconds and subsequently examined using a Hitachi TM4000Plus II Tabletop SEM, operating at an accelerating voltage of 15 kV with a backscattered electron detector. SEM images are acquired at a 500× magnification to examine the surface morphology of the microspheres.

[0209] SEM images of radioactive microspheres are collected using a Versa 3D Dual-Beaminstrument, operating at an acceleration voltage of 5 keV. No sputter coating is utilized.WSGR Docket No.66410-701601

[0210] Density

[0211] An AccuPyc 1340 helium pycnometer (Micromeritics, USA) equipped with a 1 cm3insert chamber is used to determine the density of each glass composition. Briefly, about 1.0 g to 1.5 g of glass microspheres is used for each measurement, and each measurement consists of 10 fill and purge cycles. The results are reported as the average ± standard deviation (SD) of three replicate measurements.

[0212] 19Si Magic Angle Spinning Nuclear Magnetic Resonance (MAS NMR)

[0213] 19Si MAS NMR is performed on glass compositions to determine the Qn distributionof silicon in the glass networks. Samples are run on 300Hz NMR in a 7mm rotor. The analysis will derive the SiO (Q1), SiO2(Q2), SiO3(Q3), and SiO4(Q4) molar ratios and both the integrated peak ratios as well as the deconvoluted area ratios.

[0214] Post-firing compositional analysis

[0215] Inductively coupled plasma optical emission spectroscopy (ICP-OES) is performedto verify the actual glass compositions after melting and compare against the intended theoretical compositions.

[0216] Degradation Study

[0217] To assess the chemical durability of each glass microsphere (and investigate the riskof Ho-166 and Y-90 radionuclides leaching from the glass microsphere after implantation), a degradation study is conducted. An about 0.5 g sample of each glass composition (diameter less than 45 µm) is weighed into pre-weighed 15 mL centrifuge tubes in triplicate and 10 mL of citric acid buffer solution (prepared as per ISO 10993-14: Identification and quantification of degradation products from ceramics) is subsequently added to each tube. The tubes are then capped and placed into a shaking incubator (120 revolution per minute (RPM) and 37 °C) for about 5 to about 10 days. At the end of the incubation period, samples are centrifuged (3.0 RCF, 4.4 RPM) for about 15 minutes, and supernatants are decanted from the pellet. The extracts are stored at about 4 °C for subsequent elemental analysis. Following separation of the supernatant, the pellet is rinsed with 3 mL of purified water to remove the remaining citric acid buffer. The sample is then centrifuged again for about 3 minutes, and the purified water is decanted from the pellet. The pellet in the original test tube is then dried in an oven at about 50 °C for 72 hours then subsequently weighed to determine the final mass of the glass. The percent mass loss is then determined using the following equation: ^^^^^^^^^^^^^^ ^^^^^^^^ − ^^^^^^^^^^ ^^^^^^^^% ^^^^^^^^ ^^^^^^^^ =^^^^^^^^^^^^ ^^^^^^^^ × 100

[0218] Each glass extract is diluted in about 2% hydrochloric acid for inductively coupledplasma - optical emission spectroscopy (ICP-OES) analysis of Si, Y, Ho, and Al content.WSGR Docket No.66410-701601 Elemental analysis of glass extracts is performed by an Agilent 5800 Vertical Dual View (VDV) ICP-OES using a 2% hydrochloric acid suspension media, argon carrier gas and an argon flame. Calibration curves are produced at 0, 0.5, 1, and 2 ppm concentrations using Perking Elmer pure ICP standards or TraceCERT®for each element of interest. The mean concentration of each element in mg / L is plotted against time to derive profiles for the assessment of ion release kinetics.

[0219] Neutron Activation Analysis (NAA)

[0220] NAA - Microsphere Composition Verification

[0221] The elemental composition of each microsphere post-fabrication is verified by NAA.In brief, about 50 mg of each glass microsphere is double encapsulated in a heat-sealed polyethylene vial. A series of element standards containing known quantities of each analyte are prepared in an identical fashion. The samples and element standards are exposed to a thermal neutron flux (φth= 5 × 1012n / cm2·s) for about 300 seconds at the McMaster Nuclear Reactor (McMaster University, ON, Canada). The samples are allowed to decay for about 900 seconds before the gamma spectrum is acquired (600 second live time) on an ORTEC high efficiency high-purity germanium (HPGe) detector. Count data are recorded for five Regions of Interest (ROIs) corresponding to three radionuclides of aluminum, holmium, and yttrium as shown in Table 4. The quantity of each element present in a glass sample (in weight percentage (wt %)) is ascertained by comparing the intensity of each gamma emission to the intensity of corresponding emissions in the element standard spectra. Table 4. Regions of Interest (ROIs) for gamma spectroscopy ROI Analyte Energy Center Radionuclide, . .holmium generates a gamma spectrum with lines at 1,778.99 keV (3,000 counts) and 80.58 keV (400 counts); a glass sample (50.00 mg) produces a spectrum with lines at 1,778.99 keV (2,500 counts) and 80.58 keV (1,200 counts); the glass sample can be assumed to contain 8.33 mg aluminum (2500 / 3000 counts × 10 mg) and 30.0 mg holmium (1200 / 400 counts × 10 mg).WSGR Docket No.66410-701601

[0223] NAA - Microsphere Integrity Testing

[0224] To verify that the glass microspheres can withstand the harsh conditions within thecore of a nuclear reactor, a representative sample of the glass microsphere composition is subjected to integrity testing. Briefly, an about 1.0 g sample of microspheres is weighed out into a quartz tube or ampoule. The tube is capped, wrapped in aluminum foil, and prepared for in- core irradiation according to Standard Operating Procedures. The Standard Operating Procedure typically comprises placing the foil-wrapped tube into a ballasted aluminum capsule etched with a unique identifier, cold-welding the capsule, and completing a leak-test. The capsule is placed in the designated site within the reactor core for about 14 to about 48 hours, where it experiences a nominal neutron flux of 4.2 x 1013n / cm2^s to 7 x 1013n / cm2^s.

[0225] At the end of the prescribed neutron bombardment period, the sample is removedfrom the in-core site and stored underwater for about 10 days. Then the sample is removed from the aluminum capsule, placed in a thick (more than 2 cm) lead (or tungsten) container, and transported to a lab for radionuclide quantification. In the lab, the sample (still in the foil- wrapped quartz tube) is placed in a dose calibrator (ion chamber detector) with a “Ho-166” setting. The activity is recorded, and the sample returned to the Pb / W storage container.

[0226] After about an additional 6-8 days, the sample is re-measured in the dose calibrator,then subjected to leaching testing. In brief, the microspheres are transferred into a 15 mL plastic centrifuge tube (or a similar centrifuge tube) and combined with biosimilar media such as phosphate-buffered saline (about 3 mL to about 10 mL). The activity of the sample is re- measured to account for geometry effects on detector efficiency. The sample is spun in a centrifuge to precipitate all microspheres; an aliquot of supernatant (from about 100 μL to about 300 μL) is removed, replaced with an equivalent volume of fresh media, and counted on a high- efficiency HPGe detector to quantify any radioactive material that has leached from the microspheres.

[0227] The centrifuge tube containing the microspheres is maintained in a water bath (or asimilar bath) at about 37 °C for a period of about 3-7 days. At predetermined timepoints (e.g., 3h, 24 h, 48 h, 72 h, 96 h, and / or 168 h after the start of heating), the centrifuge tube is removed from the heat briefly, spun in the centrifuge, and an aliquot of supernatant is withdrawn, replaced, and counted on the HPGe detector. As a high-efficiency detector is capable of detecting and quantifying sub-Bq levels of radioactivity, this will enable precise quantification of any Ho-166 escaping the microspheres, and thus provide information about the physical integrity of the microspheres after their in-core neutron bombardment. At the end of the about 3- 7 days period, a portion of the microspheres is imaged using a light microscope to check for any visible cracks or other physical damage.WSGR Docket No.66410-701601

[0228] Cytotoxicity

[0229] To prepare samples for cytotoxicity testing, about 1.0 g of each glass microspherecomposition is dispensed into a labelled glass scintillation vial and steam sterilized in an autoclave (Primus Sterilizer Co.) using a vacuum cycle at about 132 ºC. In accordance with ISO 10993-12: Biological evaluation of medical devices — Part 12: Sample preparation and reference materials, glass test articles and controls (negative control – polypropylene pellets, positive control – natural latex rubber) are extracted at a ratio of about 0.2 g / ml. Test articles and controls are extracted under agitation in 1× Minimal Essential Media with 5% bovine serum (1×MEM5) at about 37 ± 1 ºC with 5 ± 1% CO2. Following extraction, the test article extracts are centrifuged at about 4,000 RPM for about 15 minutes. The extract fluids are held for no more than 4 hours at room temperature before testing. The test article and positive control extracts are diluted in 1×MEM5 prior to testing, as recommended in ISO 10993-5, and the following dilutions are tested: undiluted (100%), diluted 2-fold (50%), diluted 4-fold (25%), and diluted 8-fold (12.5%).

[0230] The cytotoxicity of each glass is evaluated using a quantitative MTT assay (NelsonLaboratories, UT, United States). Mouse CCL-NCTC clone 929 cells (L929) (obtained from American Type Culture Collection (ATCC)) are seeded in a 96-well plate and incubated until approximately 50% confluent. The glass and control extracts (at each prepared dilution) are exposed to the cells by adding 100 µL to each of 6 wells in the 96 well plate. Additionally, a media control is exposed to the cells by adding 100 µL to each of 12 wells: 6 on the left of the plate and 6 on the right. The top and bottom rows of the plate are not seeded with cells and serve as the test system blank, each receiving 100 µL aliquot of 1×MEM5. The plate is then incubated at about 37 ± 1 ºC, with 5 ± 1% CO2, in humidified conditions for about 24 - 25 hours. Following incubation, the extract fluid is removed from the plate and the MTT assay is performed on the cells. Sample absorbance at 570 nm is measured on a spectrophotometer with a reference wavelength of 650 nm. The blanks that do not contain cells are used to correct the optical density readings of the test article and control extracts. The percent viability for the test article and controls is calculated using the following equation: ^^^^^^^^ ^^^^^^^^ ^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^ =^^^^^^^^ ^^^^^^^^^^ ^^^^^^^^^^^^^^ ^^^^ × 100%

[0231] A sample with a mean percent viability of less than 70% of the media control isdeemed to have cytotoxic potential in accordance with ISO 10993-5: Biological evaluation of medical devices — Part 5: Tests for in vitro cytotoxicity.WSGR Docket No.66410-701601

[0232] Optimization

[0233] A response surface optimization study using Design-Expert Software (Version 13) isconducted to enable the prediction of one optimal glass composition tailored to meet a set of optimization criteria (listed in Table 5). The optimization criteria are chosen based on material requirements for a next generation imageable radio embolic microsphere for use in TARE. Specifically, an yttrium oxide content of 0 mol% is targeted to ensure that only one radionuclide (Ho-166) is present in the optimized formulation to avoid the following logistical complications that arise from mixed Y-90 / Ho-166 systems. Namely, mixed-isotope systems limit operational flexibility, as the two radionuclides have different neutron activation rates and decay rates, meaning that any variation in neutron activation parameters or the delay-to-administration interval post-irradiation may alter the ratio of the two radionuclides present in the therapeutic dose. This may create challenges for treatment planning because the two radionuclides have different depths of penetration in tissue; the quantities of each radionuclide are expected to be consistent and known in advance to accurately plan treatment. Additionally, standard hospital equipment used to measure the activity in a radio embolic device (e.g., nuclear medicine-style ion chamber dose calibrators) cannot differentiate between radionuclides, or determine the relative fractions of two radionuclides present in a single material. As such, using a single- radionuclide composition simplifies activity quantification and provides a faster path to clinical use. Moreover, demonstrating proof-of-principle using a single-radionuclide therapeutic may build the clinician confidence required to examine more complex, mixed-radionuclide therapeutics in the future. In addition, a solution with a holmium oxide content of at least 5 mol% is targeted to permit a similar activity dose (~390 GBq / g Ho-166) to existing glass Y-90 TARE microspheres (~118 GBq / g Y-90) assuming a 24-hour irradiation at a flux of 2 × 1014n / cm2·s and a 4-day decay period for processing and transport to the clinic. Furthermore, CT imageability of the microspheres is maximized to ensure the best possible visibility on clinical CT and CBCT scans. Finally, Tg is maximized to ensure high thermal stability, which allows the microspheres to withstand elevated temperatures within the nuclear reactor, enabling activation to high specific activities. Table 5. Criterion for optimized glass formulation Factor / Response Units Lower Limit Upper Limit Importance GoalWSGR Docket No.66410-701601

[0234] Based on the optimization criterion selected, Design-Expert software systematicallygenerates potential formulations, deemed solutions, that may offer the desired properties.

[0235] Pre-Irradiation Leaching Analysis

[0236] The chemical durability of the optimized glass is assessed in triplicate at a time pointof 5 d to represent the time at which the activity present from Ho-166 would have been decayed below 10% of the initial therapeutic dose. See FIG.4. This testing is conducted with non- irradiated microspheres to establish a benchmark for comparison with the subsequent leaching test using radioactive microspheres.

[0237] For each glass sample, about 0.5 g of glass microspheres (<45 µm) is added to a pre-weighed 15 mL centrifuge tube with about 10 mL of saline solution. Tubes are then capped and placed at an approximate 45-degree angle on a shaking incubator at 120 RPM and 37 ºC for the desired time point. Following incubation, samples are centrifuged (3.0 RCF, 4.4 RPM) for about 15 minutes, and supernatants are decanted from the pellets into a separate 15 mL centrifuge tube. This tube is capped, and the extracts are stored at about 4 ºC until elemental analysis. Each glass extract is diluted in about 2% nitric acid for inductively coupled plasma - optical emission spectroscopy (ICP-OES) analysis of Si, Ho, and Al content. Elemental analysis of glass extracts is performed by an Agilent 5800 Vertical Dual View (VDV) ICP-OES using a 2% nitric acid suspension media, argon carrier gas and an argon flame. Calibration curves are produced at about 0 ppm, 0.25 ppm, 0.5 ppm, 1.0 ppm, and 2.0 ppm concentrations using TraceCERT®pure ICP standards (Sigma-Aldrich) for each element of interest. The mean concentration of each element in the extract is reported in ppm.

[0238] In-core Neutron Bombardment & Post-Irradiation Stability Testing

[0239] A 1.0 g sample of Glass No. 2 (see Table 3) is weighed into a quartz tube, capped,and sealed inside an aluminum capsule. The capsule is exposed to a thermal neutron flux of 4.2 × 1013n / cm3·s (McMaster Nuclear Reactor) for about 48 h and is subsequently decay-stored underwater for about 13 days. The Ho-166 activity present in the microspheres is measured using a multi-isotope dose calibrator (AtomLab 400, Biodex) and decay-corrected to determine the activity present at End of Irradiation (2.6 TBq).

[0240] After an additional 6-day decay period, the irradiated material is transferred to acentrifuge tube containing 3 mL of phosphate-buffered saline (PBS) and maintained at about 37 ºC (±5 ºC) for 7 days. A 300 µL aliquot of supernatant is withdrawn for analysis at about 3 h post-suspension and is replaced with fresh PBS. This is repeated at 24 h intervals for the next 4 days, and again at 7 days post-suspension. Each aliquot is subjected to high resolution gamma spectroscopy (ORTEC High-Efficiency HPGe detector) to assess the quantity of Ho-166 released from the glass over time.WSGR Docket No.66410-701601

[0241] The microspheres are examined by SEM at 10-day and 17-day post-suspension toassess any radiation induced damage. At 26-day post-suspension, the supernatant is decanted and subjected to ICP-OES (Agilent 5800 VDV) and ICP-MS (Varian 820 ICPMS) to quantify traces of aluminum, silicon, and non-radioactive holmium.

[0242] Example 5: Neutron Activation Calculations

[0243] Neutron activation calculations are conducted for each microsphere compositionlisted in Table 3 to assess the amount of therapeutic radionuclide formed under standard activation conditions (φ ≥ 2 x 1014n / cm2^s; tirradiation = 7 d). The activity of each radionuclide is estimated for the 7-day activation period, plus a 3-day cool-down period post-activation. For each glass microsphere No., a sample size of 1.0 gram is assumed. The results (shown in Table 6) demonstrate that all 16 glass microsphere formulations from Table 3 meet or exceed the necessary specific activity for TARE therapeutics at three days post-irradiation (assuming about 120 GBq / g for Y-90 and about 15 GBq / g for Ho-166). Shorter activation periods can be used to generate low specific activity microspheres for treatment planning. Table 6. Neutron activation calculations. Activity at EoB (GBq) Activity at EoB + 72 H (GBq)Notes: Glass compositions No.5 and No.16 are replicates. Glass compositions No. 10 and No.13 are replicates. ***Glass compositions No.11 and No.14 are replicates. Composition for each glass composition No. is the same as that with the same glass composition No. in Table 3.WSGR Docket No.66410-701601

[0244] Example 6: Example Glass Microsphere Synthesis and Characterization

[0245] An example formulation (Glass Microspheres No. SS5) designed within mol% ofstarting components listed in Table 7 was synthesized, manufactured into microspheres (SEM images shown in FIG.1), characterized (Table 8) with respect to their density, glass transition temperature and imageability on CT at 70 and 120 kVp (frit only), and investigated in a preclinical animal model (prototype packaging for use in pre-clinical animal study and CBCT reconstructions post administration in FIGs.2 and 3). FIG.2 shows an anterior view CBCT reconstruction of 250 mg of Synergy Spheres example microsphere in both the cranial and caudal poles of a left kidney of a swine post-administration. FIG.3 shows an anterior view CBCT reconstruction of 250 mg of Synergy Spheres example microsphere in in the caudal pole only (microspheres in cranial pole are a separate product) of a right kidney of a swine post- administration.

[0246] These SS5 glass microspheres demonstrate the feasibility of a dual-isotopecontaining glass microsphere that was visible on CT / CBCT. Table 7. Composition of an example microsphere Glass No. SiO2 Y2O3 Ho2O3 Al2O3 Table8. Physical and Chemical Characteristics of example Synergy Spheres (Glass Microspheres SS5) pre- and post- spheroidization. Pre Spheroidization Post Spheroidization

[0247] Examp e : dd t ona G ass crosp ere Synt eses and est ng

[0248] All 16 example formulations (Glass Nos. 1-16) according to Table 3 were subject toglass synthesis. All compositions were successfully melted and quenched. The quenched glasses exhibited a yellow coloration, apart from the Ho-free compositions (Glass Nos.1 and 3), which displayed a translucent / white appearance. Moreover, Glass Nos.2 and 12 demonstrated reducedWSGR Docket No.66410-701601 homogeneity compared to the other glass compositions. However, subsequent XRD analysis confirmed the amorphous nature of these two glasses (Glass Nos.2 and 12). Below are summary of the tests conducted on the 16 glass samples.

[00249] Particle Size Analysis

[0250] All glasses were milled and sieved to meet the <45 µm particle size. The Dx10,Dx50, and Dx90 values were measured for each composition and are provided in Table 9. Table 9 presents key properties including particle size distribution, density, CT imageability (70 kVp,120 kVp), Tg(onset), and cell viability. Table 9. Material characterization of the developed particles Glass Dx (10) Dx (50) Dx (90) Density CT (70 CT (120Tg [ºC] Cell

[00251] XRD analysis

[0252] All glasses were confirmed to be amorphous and free from identifiable crystallinespecies. A representative XRD spectrum of Glass No.10 from the series is provided in FIG.5.WSGR Docket No.66410-701601

[0253] Density

[0254] Density values ranged from 3.0240 g / cm³ to 4.0605 g / cm³ (Table 9). The strongestcorrelation observed from the density data was an increasing density with an increasing Ho₂O₃ content. The density data can be fitted to a model to analyze the relative influence of each glass constituent on the density response.

[0255] Radiopacity Evaluation (CT)

[0256] The radiopacity of glasses varied with glass composition, with HU values rangingfrom 9420 to 19847 (Table 9). The CT data can be fitted to a model to evaluate the factors contributing to an increase in the radiopacity at 70 kVp. The one factor that contributes to a decrease in radiopacity is SiO₂. The strongest correlations observed from the CT data was an increasing CT imageability with an increasing Ho₂O₃ content.

[0257] The observed level of radiopacity is about 4–8 times greater than half-strengthIsovue®370, a commercial iodine-based contrast agent, scanned under identical conditions. See, S. Kehoe, E. Tonkopi, R. J. Abraham, and D. Boyd, “Predicting the thermal responses and radiopacity of multicomponent zinc-silicate bioglasses: A focus on ZnO, La2O3, SiO2 and TiO2,” J Non Cryst Solids, vol.358, no.23, pp.3388–3395, Dec.2012. These glass microspheres can enable CT-based dosimetry and may eliminate the need for adjunctive imaging modalities such as SPECT or PET. Real-time tracking of microsphere distribution during both treatment planning and therapeutic procedures may allow clinicians to receive direct, actionable feedback. This capability enhances procedural control, enabling immediate adjustments to treatment parameters and confirmation of microsphere delivery, thereby optimizing and verifying dosimetry. Real-time CT-based imaging ensures more accurate, personalized dose delivery to tumor tissues while mitigating the risk of off-target effects. Additionally, the ability to visualize microspheres intra-procedurally using readily available imaging systems such as angiography, x- ray fluoroscopy, CT, or CBCT may provide desired clinical values. These imaging systems enhance spatial resolution, reduce misregistration errors, and simplify procedural workflows, ultimately improving both procedural efficiency and patient outcomes.

[0258] DSC

[0259] The Tg values ranged from 872 to 895 °C (Table 9). The Tg data can be fitted to amodel to evaluate the glass constituents contributing to an increase in Tg. The model suggests that no constituents contributed to a decrease in Tg. No strong correlations were observed between the glass constituents and the Tg response.

[0260] NAA

[0261] The measured gamma counting data was obtained in net counts per second (cps). Foreach element standard, a calibration factor (cps / mg) was obtained for each gamma energy usingWSGR Docket No.66410-701601 the following equation, where cpsstdis the gamma counts measured for the element oxide standard and massstd is the mass of the element in the standard: ^^^^^^ ^^^^^^^^^^^^^^=

[0262] The gamma counting data atconverted to mass of analyte in thesample. The mass of analyte values were divided by the starting mass of the glass sample (~0.05 g) and multiplied by 100% to determine the wt % of Y, Ho, and Al at all five ROIs (Table 4). To determine the final wt % of holmium in each sample, the 80 keV and 1379 keV emissions of Ho-166 were averaged to obtain a single value. The yttrium data at 202 keV and 479 keV were treated analogously. The measured gamma count rates for the 479 keV (Y-90m) emission in Glass Nos.8 and 14 were very low (<3.5 cps) and consequently had high uncertainty (>14%). These two data points were therefore excluded from the analysis. Table 10 shows the predicted (theoretical) values and empirical values for glass constituents in each Glass No. sample. Table 10. Empirical and predicted compositions (wt. %) of glass samples Glass Ho Ho Y Y Al AlNotes: N / A- not availableWSGR Docket No.66410-701601

[0263] The results of the NAA show that the empirical results align well with thetheoretically calculated compositions (Table 10), indicating that the melting and spheroidization processes have not significantly altered the chemical composition of the glasses. The apparent deviations for some of the Y values are an artefact of the much greater formation rate of Ho-166 and Al-28 compared to Y-90m: this results in very low uncertainty within the Ho-166 and Al-28 counting statistics (<0.2% and 1%, respectively), but gives rise to undesirable spectral features (e.g., Compton scattering, X-ray escape peaks, backscattering) that increase the background count rates and make it difficult to accurately quantify low count-rates from minor radionuclides such as Y-90m present in the sample. The apparent absence of Y in Glass No.4 is likely because the count rate at the predicted concentration of 0.4 wt.% would be below the limit of detection.

[0264] Cytotoxicity

[0265] All undiluted test samples (100%) had mean percent cell viabilities of 70% or greater(Table 9), indicating that the test articles do not have a cytotoxic potential. The mean optical density (OD) of the media controls on the left of the plate and the media controls on the right of the plate did not differ by more than 15% from the mean OD of all the media controls. The mean OD of all the media controls was ≥ 0.2, which indicates proper cell growth. Media control cells showed normal growth characteristics when observed under magnification. Positive control extracts (undiluted) reduced the viability to less than 70% of the media control. Negative control extracts did not reduce the viability to less than 70% of the media control.

[0266] Optimization

[0267] One solution was derived from the optimization criteria listed in Table 5. Thecomposition of the optimized formulation as well as the predicted values for density, CT (70 kVp), and Tg, are included in Table 11. Table 11. Composition of optimized formulation and predicted values for modelled parameters SiO2 Y2O3 Ho2O3 Al2O3D itCT

[0268] This solution has an identical formulation to Glass No. 2 from the original designspace, indicating that Glass No.2 was the most optimal formulation to meet the desired criterion. Ho-166 has three key advantages over Y-90. Most important among these is the substantially higher neutron capture cross-section of the165Ho(n,γ)166Ho nuclear reaction compared to the89Y(n,γ)90Y transformation (61.2 b vs 1.28 b). This enables the production of much larger quantities of Ho-166 per gram of microspheres, affording clinicians more flexibilityWSGR Docket No.66410-701601 in the absorbed dose they can administer to a fixed treatment volume. A second factor is the slightly lower beta energy of Ho-166 compared to Y-90 (Eβmax = 1.85 MeV vs.2.28 MeV), which curtails the distance the therapeutic particles travel in vivo, thereby minimizing damage to healthy tissues. Finally, Ho-166 emits a low-energy, low-intensity gamma ray (Eγ = 80.6 keV, 6.56%) that enables visualization of the microspheres using standard SPECT scanners; this is advantageous because it can be used to identify patients who are ineligible for TARE treatment due to shunting of the radioactive particles to the lungs.

[0269] Pre-Irradiation Leaching Analysis

[0270] The concentration of Si4+, Ho3+, and Al3+ released from Glass No. 2 was measuredfrom extracts collected after 5 days of incubation in saline. Si and Al were not detectable in the sample extract. After accounting for dilution factors, the average Ho concentration in the sample extract was 0.445 ppm. This concentration correlates to approximately 0.008% of the theoretical Ho in the sample.

[0271] In-core Neutron Bombardment and Stability Testing

[0272] The microsphere sample that was activated to 2.6 TBq / g and showed no signs ofphysical degradation when assessed by SEM (FIGs.6 and 7). SEM images of the glass microspheres pre-irradiation (representative SEM image of Glass No.2 shown in FIG.6, pre- irradiation (500× magnification)) show consistency in the spherical morphology of the samples and provide visual confirmation of the <45 µm particle size distribution. Microspheres appear to be free from debris or particulate. Re-imaging of glass 2 after having undergone neutron activation (FIG.7, post irradiation to 2.6 TBq / g Ho-166 (2000× magnification)) shows similar morphology, particle size, and surface characteristics. ICP-MS data demonstrated that <0.1 ppm of the holmium was released from the microspheres after 25 days suspension in phosphate buffered saline, confirming the stability of the microspheres post-irradiation.

[0273] While preferred embodiments of the present invention have been shown anddescribed herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. It is not intended that the invention be limited by the specific examples provided within the specification. While the invention has been described with reference to the aforementioned specification, the descriptions and illustrations of the embodiments herein are not meant to be construed in a limiting sense. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. Furthermore, it shall be understood that all aspects of the invention are not limited to the specific depictions, configurations or relative proportions set forth herein which depend upon a variety of conditions and variables. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. ItWSGR Docket No.66410-701601 is therefore contemplated that the invention shall also cover any such alternatives, modifications, variations or equivalents. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.

Claims

WSGR Docket No.66410-701601 CLAIMS1. A microsphere, comprising:(i) an aluminosilicate; and (ii) one or more radionuclides, wherein the microsphere is radioactive, and wherein the microsphere is imageable by computerized tomography (CT) or cone-beam computed tomography (CBCT).

2. The microsphere of claim 1, wherein the one or more radionuclides comprises holmium-166.

3. A microsphere, comprising:(i) an aluminosilicate; and (ii) one or more radionuclides comprising holmium-166, wherein the microsphere is radioactive.

4. The microsphere of claim 3, wherein the microsphere is imageable.

5. A microsphere, comprising:(i) an aluminosilicate; and (ii) holmium oxide.

6. The microsphere of claim 5, wherein the microsphere is imageable.

7. The microsphere of any one of claims 3-6, wherein the microsphere is imageable bycomputerized tomography (CT) or cone-beam computed tomography (CBCT).

8. The microsphere of any one of claims 1-7, wherein the microsphere comprises (a)holmium, and (b) at least another radionuclide.

9. The microsphere of claim 8, wherein the microsphere comprises Ho-166, and optionallyY-90.

10. The microsphere of claim 8 or 9, wherein the microsphere is imageable by holmiumand / or the at least one radionuclide.

11. The microsphere of any one of claims 1-10, wherein the microsphere is imageable byintra-procedural angiography, x-ray fluoroscopy, magnetic resonance imaging (MRI), ultrasound, positron emission tomography (PET), or single-photon emission computed tomography (SPECT), or a combination thereof.

12. The microsphere of any one of claims 1-11, wherein the microsphere comprises:from about 0.50 to about 0.90 mole fraction of silicon dioxide; from about 0.05 to about 0.30 mole fraction of aluminum oxide; and from about 0.001 to about 0.25 mole fraction of holmium oxide.

13. The microsphere of claim 12, wherein the microsphere comprises:from about 0.60 to about 0.80 mole fraction of silicon dioxide;WSGR Docket No.66410-701601 from about 0.10 to about 0.25 mole fraction of aluminum oxide; and from about 0.001 to about 0.20 mole fraction of holmium oxide.

14. The microsphere of claim 12, wherein the microsphere comprises:from about 0.65 to about 0.75 mole fraction of silicon dioxide; from about 0.14 to about 0.25 mole fraction of aluminum oxide; and from about 0.001 to about 0.15 mole fraction of holmium oxide.

15. The microsphere of claim 12, wherein the microsphere comprises:from about 0.65 to about 0.74 mole fraction of silicon dioxide; from about 0.14 to about 0.19 mole fraction of aluminum oxide; and from about 0.001 to about 0.12 mole fraction of holmium oxide.

16. The microsphere of any one of claims 1-15, wherein the microsphere further comprisesyttrium.

17. The microsphere of any one of claims 1-15, wherein the microsphere further comprisesyttrium oxide.

18. The microsphere of claim 17, wherein the microsphere further comprises from about0.001 to about 0.15 mole fraction of yttrium oxide.

19. The microsphere of claim 17, wherein the microsphere further comprises from about0.001 to about 0.14 mole fraction of yttrium oxide.

20. The microsphere of claim 17, wherein the microsphere further comprises from about0.001 to about 0.12 mole fraction of yttrium oxide.

21. The microsphere of any one of claims 1-20, wherein the microsphere has an averagediameter from about 5 μm to about 4500 μm.

22. The microsphere of claim 21, wherein the microsphere has an average diameter fromabout 5 μm to about 1300 μm, from about 5 μm to about 1200 μm, from about 5 μm to about 30 μm, from about 10 μm to about 35 μm, from about 10 μm to about 45 μm, from about 20 μm to about 30 μm, from about 20 μm to about 40 μm, from about 20 μm to about 50 μm, from about 40 μm to about 500 μm, from about 40 μm to about 300 μm, from about 300 μm to about 500 μm, from about 500 μm to about 700 μm, from about 700 μm to about 1200 μm, from about 1200 μm to about 1500 μm, from about 1500 μm to about 2000 μm, from about 2000 μm to about 2500 μm, from about 2500 μm to about 3000 μm, from about 3000 μm to about 3500 μm, from about 3500 μm to about 4000 μm, or from about 4000 μm to about 4500 μm.

23. The microsphere of any one of claims 1-22, wherein the microsphere remains durablefollowing neutron irradiation with a high thermal neutron flux.WSGR Docket No.66410-70160124. The microsphere of claim 23, wherein the high thermal neutron flux is neutronirradiation conditions having φ no less than 5 x 1013n / cm2•s for a duration of time (t) no less than 24 h in a nuclear research reactor.

25. The microsphere of any one of claims 1-24, wherein the microsphere is adjustable in atleast one property selected from the group consisting of ratio of different types of radiation, half- life, tissue penetration depth, specific activity per microsphere, and imaging capabilities.

26. The microsphere of claim 25, wherein the at least one property correlates to a ratio ofholmium to the at least one radionuclide in the microsphere.

27. The microsphere of claim 25 or 26, wherein the specific activity is from about 50 toabout 5000 Bq / microsphere.

28. The microsphere of any one of claims 1-27, wherein the microsphere is a theranostic.

29. The microsphere of any one of claims 1-27, wherein the microsphere comprises aradionuclide that is imageable and emitting therapeutic radiation.

30. The microsphere of any one of claims 1-29, wherein the microsphere is glass.

31. A method comprising: administering to a subject, a plurality of microspheres, wherein amicrosphere of the plurality of microspheres is as in any one of claims 1-30.

32. The method of claim 31, further comprising: imaging at least a section of the plurality ofmicrospheres at or near an organ of the subject.

33. The method of claim 32, wherein the organ is a liver.

34. The method of claim 32, wherein the organ is anus, arteries, appendix, adrenal gland,brain, bones, bronchi, bladder, bone marrow, bulbourethral gland, colon, cervix, clitoris, cerebellum, diaphragm, ear, eye, fallopian tube, genital, gallbladder, heart, hypothalamus, interstitium, kidney, joint, lung, larynx, ligament, lymph node, large intestine, lymphatic vessel, mouth, mesentery, mammary glands, nose, nerve, nasal cavity, ovaries, esophagus, penis, pancreas, pharynx, placenta, prostate, pineal gland, pituitary gland, parathyroid gland, rectum, skin, spleen, scrotum, stomach, spinal cord, small intestine, salivary gland, skeletal muscles, seminal vesicles, subcutaneous tissue, testes, tendons, tongue, thyroid, trachea, thymus gland, ureters, urethra, uterus, vulva, veins, vagina, vas deferens, or vestigial organ.

35. The method of any one of claims 32-34, wherein the imaging is computerizedtomography (CT) imaging or cone-beam computed tomography (CBCT) imaging.

36. The method of any one of claims 32-34, wherein the imaging is computerizedtomography (CT) imaging, cone-beam computed tomography (CBCT) imaging, positron emission tomography (PET) imaging, radiographic imaging, intra-procedural angiography imaging, x-ray fluoroscopy imaging, magnetic resonance imaging (MRI) imaging, ultrasoundWSGR Docket No.66410-701601 imaging, or single-photon emission computed tomography (SPECT) imaging, or a combination thereof.

37. The method of any one of claims 31-36, wherein the plurality of microspheres areradioactive.

38. The method of any one of claims 31-37, wherein the microsphere is a theranostic.

39. The method of any one of claims 31-37, wherein the microsphere provides radionuclideimaging and emits therapeutic radiation.

40. The method of any one of claims 31-39, wherein the microsphere is glass.

41. The method of any one of claims 31-40, wherein the administering is via intra-arterial orintravenous delivery.

42. A method comprising:(i) in a treatment planning step: administering to a subject, a first plurality of microspheres; and (ii) in a therapeutic treatment step: administering to the subject a second plurality of microspheres, wherein a microsphere of the first plurality of microspheres and the second plurality of microspheres is as in any one of claims 1-30.

43. The method of claim 42, further comprising(a) in the treatment planning step: imaging at least a section of the first plurality of microspheres at or near an organ of the subject; and (b) in the therapeutic treatment step: imaging at least a section of the second plurality of microspheres at or near an organ of the subject.

44. The method of claim 43, wherein the imaging in (a) and the imaging in (b) are in real-time.

45. The method of any one of claims 42-44, wherein the imaging in (a) and the imaging in(b) are conducted in an interventional radiology (IR) suite in which the subject is being treated.

46. The method of any one of claims 42-45, wherein the first plurality of microspheres issubstantially the same as the second plurality of microspheres in terms of chemical composition and / or physical characteristics.

47. The method of any one of claims 42-46, the imaging in (a) and the imaging in (b) arecomputerized tomography (CT) imaging or cone-beam computed tomography (CBCT) imaging.

48. The method of any one of claims 42-46, wherein the imaging in (a) and the imaging in(b) are computerized tomography (CT) imaging, cone-beam computed tomography (CBCT) imaging, positron emission tomography (PET) imaging, radiographic imaging, intra-procedural angiography imaging, x-ray fluoroscopy imaging, magnetic resonance imaging (MRI) imaging,WSGR Docket No.66410-701601 ultrasound imaging, or single-photon emission computed tomography (SPECT) imaging, or a combination thereof.

49. The method of any one of claims 42-48, wherein the administering in (i) is via intra-arterial or intravenous delivery.

50. The method of any one of claims 42-49, wherein the administering in (ii) is via intra-arterial or intravenous delivery.

51. The method of any one of claims 31-50, wherein the subject is a human.

52. A method comprising (a) administering to a subject a microsphere comprising (i)alumina and silica, and (ii) one or more radionuclides, and (b) imaging a body of the subject to identify a location of the microsphere within the body of the subject.

53. The method of any one of claims 42-52, wherein the microsphere is a theranostic.

54. The method of claim 52 or 53, wherein the microsphere provides radionuclide imagingand emits therapeutic radiation.

55. The method of any one of claims 42-54, wherein the microsphere is glass.

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