Core / shell-type radioactive nanoparticles useful in targeted radiotherapy

Abstract

The present invention relates to a core / shell radioactive nanoparticle comprising: - a porous silica core comprising one or more alpha-emitting radionuclides and one or more beta-emitting radionuclides, and - a metallic shell. The present invention also relates to the use of this radioactive nanoparticle as a medicinal product, particularly in the prevention and / or treatment of cancer, and / or as an imaging agent.

Description

Title of the invention: Radioactive core / shell nanoparticles useful in targeted radiotherapy FIELD OF THE INVENTION

[0001] The present invention relates to core / shell type nanoparticles encapsulating two types of radionuclides, particularly useful in cancer radiotherapy. Advantageously, these nanoparticles are useful in a theranostic approach. STATE OF THE ART

[0002] In nuclear medicine, radioactive elements are used for the diagnosis or treatment of cancer.

[0003] Radiotherapy has been used for many decades for the treatment of cancer. It involves radiation, also called radiation, to destroy cancer cells and / or inhibit their growth. Very often, this radiation is delivered via a source external to the patient's body, for example through the use of X-rays. Radiotherapy can also be delivered by administering to the patient a radionuclide that will specifically target the tumor and emit short-range (beta- radiation) or very short-range (alpha radiation) ionizing radiation, in a localized manner, so as to destroy the surrounding cancer cells. Other types of radionuclide (beta+ radiation), visible in imaging, are useful for the diagnosis of cancer.

[0004] Whether for imaging or therapy, the transport of radiopharmaceuticals within the body is generally carried out using vectors specific to the therapeutic target such as antibodies, peptides or aptamers. Nanoparticle (NP) systems enclosing the radionuclide have also been developed in recent years such as conjugated polymer NPs, liposomes, micelles or inorganic NPs (for example mesoporous silica NPs, iron oxide NPs, gold NPs or calcium phosphate NPs).

[0005] However, while radiotherapy can indeed limit the growth of cancer cells and destroy them, ionizing radiation, particularly alpha radiation, can be harmful to healthy cells. For example, during the disintegration of an alpha-emitting radionuclide, the released daughter isotope, which may itself be an alpha emitter, is likely to circulate within the body and affect healthy cells. This is particularly the case when the parent radionuclide is vectorized to the cancer cells using a specific vector such as an antibody; The released daughter isotope will not be bound to this antibody and will therefore be free to circulate throughout the body.

[0006] A need therefore exists for a system for delivering an effective dose of therapeutic ionizing radiation, in order to inhibit the growth of cancer cells while preventing the propagation of this radiation to healthy cells, thus ensuring patient safety.

[0007] Furthermore, in a so-called theranostic approach, a radiopharmaceutical visible in imaging is first used to map the cancer cells in the body. Then, another radiopharmaceutical emitting therapeutic radiation, generally alpha or beta- radiation, is administered to the patient, for example using radioactive nanoparticles that will specifically target the cancer cells identified during the first step. Different radiopharmaceuticals are therefore used for the diagnostic step and for the treatment step.

[0008] To improve the practicality of such a theranostic approach, and to reduce its cost, it would be interesting to have a single tool to carry out both the imaging step and the therapy step. Such a tool would also have the advantage of allowing the imaging and therapy steps to be carried out simultaneously. For example, it would be possible to monitor by imaging the inhibition of tumor cell growth directly while the radiopharmaceutical is exerting its action.

[0009] However, many problems arise in the development of such a bifunctional tool. Indeed, it is necessary that the radionuclides used together for imaging on the one hand and therapy on the other hand are compatible with each other. The radionuclides must in particular be chemically compatible, that is to say they must not react with each other and modify the properties and stability of each. The radionuclides must be physically compatible, that is to say they must have physical characteristics (for example half-life times) allowing their joint use. In addition, the radionuclides must be compatible in their medical use. Furthermore, the quantities of each radionuclide in the nanoparticles must be strictly controlled so that each delivers a quantity of radiation allowing imaging and therapy while ensuring patient safety. Statement of the invention

[0010] Surprisingly, the inventors have developed a tool in the form of a core / shell type nanoparticle, capable of delivering an effective dose of therapeutic radiation to treat a tumor while limiting its impact. on healthy cells. The nanoparticle of the invention is also suitable for theranostic use meeting the needs expressed above.

[0011] A first object of the invention relates to a radioactive nanoparticle of the core / shell type comprising:

[0012] - a core based on a porous material comprising one or more radionuclides emitters and one or more emitting radionuclides [3, and

[0013] - a metal envelope.

[0014] The nanoparticle of the invention is notably characterized in that the radionuclides are adsorbed on the porous material.

[0015] In some embodiments, the envelope is made of a material selected from metals, metal oxides, metal alloys, mixtures thereof and combinations thereof. In particular, it comprises, and is made of, titanium oxide.

[0016] In some embodiments, one or more a-emitting radionuclide(s) is (are) selected from the group consisting of 225Ac, 223Ra, 21'At, 212Bi, 227Th, 224Ra, 221Fr and 213Po.

[0017] In some embodiments, the one or more [3] emitting radionuclide(s) is (are) independently selected from the group consisting of [3+] emitting radionuclide(s), [3-] emitting radionuclide(s) and a combination thereof.

[0018] In certain embodiments, one or more [3] emitting radionuclide(s) is (are) selected from the group consisting of [3+] emitting radionuclide(s), in particular 89Zr, 18F, nC, 13N, 150,68Ga, 82Rb, MCu, 124I and 207Bi.

[0019] In certain embodiments, one or more [3-emitting radionuclide(s) is (are) selected from the group consisting of [3-emitting radionuclide(s), in particular 1311,89Sr, 153Sm, 32P, 90Y, 166Ho, 177Lu, 188Re, 169Er, 145Pm, 67Cu and 212Pb.

[0020] A second subject of the present invention relates to a pharmaceutical composition comprising a radioactive nanoparticle according to the invention, and a pharmaceutically acceptable excipient.

[0021] A third subject of the invention relates to a radioactive nanoparticle according to the invention, or a pharmaceutical composition according to the invention, for its use as a medicament, in particular as a radiopharmaceutical in the treatment of cancer.

[0022] A fourth subject of the invention relates to a radioactive nanoparticle according to the invention, comprising one or more α-emitting radionuclides and one or more [3+]-emitting radionuclides, or a pharmaceutical composition according to the invention comprising such nanoparticles, for its use as an imaging agent.

[0023] A fifth subject of the invention relates to a radioactive nanoparticle according to the invention, comprising one or more α-emitting radionuclides and one or more [3+]-emitting radionuclides, or a pharmaceutical composition according to the invention comprising such nanoparticles, for its joint use for the imaging and treatment (and / or prevention) of cancer.

[0024] A sixth subject of the invention relates to a radioactive nanoparticle according to the invention, comprising one or more α-emitting radionuclides and one or more [3+]-emitting radionuclides, for its use in a method of therapeutic radiation dosimetry having reached the therapeutic target, comprising: i. administration of the nanoparticles into the body, the nanoparticles having a known ratio of therapeutic radiation-emitting radionuclides to [3+] emitting radionuclides; ii. visualization by imaging of nanoparticles, in particular by PET imaging, and determination of the intensity of the signal emitted by the emitting radionuclides [3+ iii. quantification of the activity of the emitting radionuclides [3+ using the intensity of the signal determined in step ii) iv. quantification of the activity of therapeutic radiation-emitting radionuclides using the ratio of therapeutic radiation-emitting radionuclides / [3+]-emitting radionuclides. DESCRIPTION OF FIGURES

[0025] [Fig.lA] represents the SEM images of the SiO2 NPs.

[0026] [Fig. IB] represents the elementary mapping obtained by SEM-EDX of the NPs.

[0027] [Fig .2] represents the high resolution images obtained by Electron Microscopy in Transmission (MET) of SiO2 / TiO2 NPs.

[0028] [Fig.3] represents the high-resolution images obtained by Transmission Electron Microscopy (TEM) of SiO2 / TiO2 NPs at very small scale.

[0029] [Fig.4] represents the XPS spectra of SiO2 and SiO2-TiO2 NPs: (a) overview, (b) Si 2p, (c) Ti 2p and (d) O 1s.

[0030] [Fig.5] represents the PET images: (a) for SI taken immediately after injection (b) after 24 h; (c) for S2 taken immediately after injection; (d) after 90 h. DETAILED DESCRIPTION OF THE INVENTION Definitions “One” or “#An#”

[0031] For the purposes of the present invention, the expression “comprises a” means “comprises at least one” or “comprises one or more”. For example, the expression “comprising a radionuclide” means “comprises one or more radionuclides”.

[0032] The term “nanoparticle” (or NP) designates a spherical solid particle having a size, that is to say a diameter, ranging from a few nanometers to a few hundred nanometers.

[0033] The term "core / shell" (or "core / shell") nanoparticle refers to a nanoparticle whose core (the interior of the nanoparticle) is uniformly coated with a surface shell having a composition different from that of the core.

[0034] The term "radionuclide" (or radioisotope) refers to a radioactive atomic element, that is, unstable and capable of disintegrating into another element, called a daughter isotope, by emitting ionizing radiation. The daughter isotope may itself be a radionuclide (it will be called a daughter radionuclide), or not. The daughter radionuclide does not necessarily emit the same type of ionizing radiation as the parent radionuclide from which it originates.

[0035] The half-life of a radionuclide corresponds to the time required for half of the radioactive nuclei initially present to have disintegrated. The activity of the radionuclide is then equal to half of the initial activity.

[0036] The term "ionizing radiation" designates radiation, that is to say an emission of particles of matter and energy, having an energy level sufficiently high to cause the ionization of the matter crossed. Among ionizing radiation, we distinguish in particular alpha radiation (a) consisting of helium nuclei, beta radiation (|3) consisting of electrons or positrons and gamma radiation (y) consisting of photons.

[0037] The term "α-emitting radionuclide" therefore designates a radionuclide as defined above emitting α radiation (also referred to as an α particle) during its disintegration into a daughter isotope. It should be noted that the daughter isotope of an α-emitting radionuclide may also be an α-emitting radionuclide, or a radionuclide emitting another radiation, for example an α-emitting radionuclide [3.

[0038] The term "[3]-emitting radionuclide" therefore designates a radionuclide as defined above emitting [3] radiation (also referred to as a |3] particle during its disintegration into a daughter isotope. It should be noted that the daughter isotope of a [3]-emitting radionuclide may also be a [3]-emitting radionuclide, or a radionuclide emitting another radiation, for example an a-emitting radionuclide.

[0039] Radiotherapy is a treatment method that uses ionizing radiation to destroy cancer cells.

[0040] The activity of a radioactive source is expressed in Becquerel (Bq). One Bq is equivalent to one disintegration per second.

[0041] The absorbed radioactive dose corresponds to the quantity of energy absorbed per unit mass of the exposed material. The dose is expressed in Gray (Gy) and IGy = Uoule / kg.

[0042] The equivalent dose is a dosimetric quantity allowing the harmfulness of a given absorbed dose (Gy) to be translated onto the same reference scale, in order to evaluate the real risk of said absorbed dose. Indeed, for the same absorbed dose (in Gy), the risk to the exposed living matter is not the same depending on the type of radiation, the exposure time, and the sensitivity of the exposed living matter. For example, for the same absorbed dose, alpha radiation is approximately 4 to 5 times more toxic for cells than gamma or X radiation. The equivalent dose is expressed in Sievert (Sv) with 1 Sv = Dose (Gy) x Radiation quality factor. The equivalent dose value in Sievert of alpha radiation will therefore be 4 to 5 times higher than the equivalent dose of gamma or X radiation. Radioactive nanoparticle

[0043] The nanoparticle of the invention typically has a size ranging from 5 nm to 300 nm, preferably from 50 nm to 280 nm, more preferably from 100 nm to 250 nm and in particular from 180 nm to 250 nm.

[0044] The radioactive nanoparticle of the invention has a core / shell type structure as defined below.

[0045] - The heart

[0046] The radioactive nanoparticle of the invention has a core based on a porous material, for example mesoporous. “Based on a porous material” means that the porous material represents the main constituent of the core. The core is notably made of this porous material. The porous material is typically chosen from porous silica, zeolites such as aluminosilicates (clinoptilolite, chabazite or modernity), and MOFs (metal-organic frameworks) such as ZIFs (zeolitic imidazolate frameworks) for example ZIF-8. Preferably, the core is based on, in particular made of, porous silica.

[0047] In particular, silica is mesoporous, that is to say that it has pores having a size less than 50 nm, ranging in particular from 0.3 nm to 50 nm, which gives it a particularly large active surface. In addition, the pores have numerous deprotonated Si-O- sites which will facilitate and stabilize the adsorption of radionuclides within the pores. The size of the pores makes it possible to adsorb more or less radionuclides, depending on the activity sought for the nanoparticle. The larger the diameter of the pores, the higher the quantity of radionuclides adsorbed on the silica.

[0048] The heart is notably biodegradable.

[0049] -The envelope

[0050] The core is coated with a metal envelope forming a uniform layer on the surface of the nanoparticle.

[0051] The role of the envelope is in particular to retain within the nanoparticle, in other words to sequester, the radionuclides and to prevent their diffusion outside the nanoparticle, while allowing the ionizing radiation emitted during the disintegration of the radionuclide to pass through. Since the nanoparticle is intended to be used within the human body, the role of the envelope is therefore to prevent the circulation within the body of radionuclides, which have a high toxicity, while allowing the ionizing radiation useful for radiotherapy and medical imaging to pass through. The envelope also makes it possible to sequester the daughter isotopes resulting from the degradation of the radionuclides initially present in the nanoparticle.

[0052] The envelope is made of a material chosen from metals, metal oxides, metal alloys, their mixtures and their combinations.

[0053] In some embodiments, the shell comprises or is made of a metal such as gold, platinum or combinations thereof. In other embodiments, the shell comprises or is made of a metal oxide such as titanium oxide, silica or combinations thereof. Preferably, the shell is made of titanium oxide. Titanium oxide has the advantage of being chemically inert and easily functionalizable.

[0054] The metal shell typically has a thickness ranging from 1 nm to 100 nm, preferably from 1 nm to 50 nm, more preferably from 2 nm to 20 nm.

[0055] In certain embodiments, the envelope is functionalizable. It can in particular be functionalized with one or more targeting molecules capable of targeting a site to be treated and of leading the nanoparticles there (active targeting). For example, the targeting molecules are chosen from antibodies, peptides or proteins. They can be linked to the surface of the nanoparticle via a linker if necessary.

[0056] - Radionuclides

[0057] The radioactive nanoparticle according to the invention comprises one or more α-emitting radionuclide(s) and one or more [3.

[0058] When the radioactive nanoparticle comprises an α-emitting radionuclide, this means that it contains a single type of α-emitting radionuclide. When the radioactive nanoparticle comprises several α-emitting radionuclides, this means that it comprises α-emitting radionuclides of different nature, i.e. different atomic elements. The same understanding applies to α-emitting radionuclides [3.

[0059] The radionuclides are adsorbed on the porous material of the core of the nanoparticle.

[0060] The elements listed below are understood to be the radionuclides initially present within the nanoparticle. Of course, during the lifetime of the nanoparticle, the radionuclides initially present disintegrate, one or more times, depending on their half-life and the duration during which the nanoparticle is administered, and the nanoparticle then comprises the daughter radionuclides resulting from this or these disintegrations. This means that the daughter radionuclides also remain sequestered within the nanoparticle of the invention.

[0061] The a-emitting radionuclides are for example independently chosen from 225 Ac, 223 Ra, 21' At, 212 Bi, 227 Th, 224 Ra, 221 Fr and 213 Po. Preferably, the a-emitting radionuclides are chosen from Ac and Ra.

[0062] The [3] emitting radionuclides are chosen from [3+] emitting radionuclides and [3-] emitting radionuclides. The radioactive nanoparticle of the invention may comprise one or more [3+] emitting radionuclides, one or more [3-] emitting radionuclides or a mixture of [3+] and [3-] emitting radionuclides. Preferably, the radioactive nanoparticle of the invention comprises one or more [3+] emitting radionuclides or one or more [3-] emitting radionuclides.

[0063] The [3+] emitting radionuclides are for example chosen from 89Zr, 18F, nC, 13N, 15 0.68Ga, 82Rb, 64Cu, 124I and 207Bi. Preferably, the [3+] emitting radionuclides are chosen from 89Zr and 64Cu.

[0064] The emitting radionuclides [3- are for example chosen from 1311,89Sr, 153Sm, 32P, 90Y, 166Ho, 177Lu, 188Re, 169Er, 145Pm, 67Cu and 212Pb. Preferably, the emitting radionuclides [3- are chosen from 90Y, 67Cu, 212Pb and 177Lu.

[0065] Thus, in a first variant, the radioactive nanoparticle of the invention comprises one or more α-emitting radionuclides and one or more [3+]-emitting radionuclides, and is devoid of [3-]-emitting radionuclides. Such a nanoparticle is particularly useful in a theranostic approach, consisting of both an imaging agent and a therapeutic agent. In particular, such a nanoparticle makes it possible to carry out effective detection and visualization of cancer cells, while delivering a dose of therapeutic ionizing radiation sufficient to inhibit the growth of cancer cells.

[0066] In this first variant, the radioactive nanoparticle preferably comprises a single emitting radionuclide a, notably chosen from 225Ac and Ra, and a single emitting radionuclide [3+, notably Zr.

[0067] In a second variant, the radioactive nanoparticle of the invention comprises one or more α-emitting radionuclides and one or more [3- emitting radionuclides, and is devoid of [3+ emitting radionuclides. Such a nanoparticle is particularly useful in targeted radiotherapy and makes it possible to deliver an effective dose of therapeutic radiation to the patient while ensuring their safety. Indeed, by combining these two types of radiation within the same nanoparticle, it is possible to reduce the dose of alpha radiation delivered, which is the most dangerous, and to achieve the necessary therapeutic dose with beta-radiation, which is less harmful to health.

[0068] In this second variant, the radioactive nanoparticle comprises a single emitting radionuclide a, notably chosen from Ac and Ra, and a single emitting radionuclide [3-, notably chosen from 90Y, 67Cu, 212Pb and 177Lu.

[0069] The quantity of each radionuclide in the nanoparticle defines its activity, expressed in Becquerel. Thus, the nanoparticle of the invention has an activity defined in alpha radiation and an activity defined in beta radiation. The value of these activities depends on the type of radionuclide, the nature of the therapeutic activity, and possibly imaging, envisaged (size and location of the tumor, weight of the patient, etc.). The activity of each radionuclide in the nanoparticle will be determined so as to limit the toxicity of the nanoparticle with respect to the patient while maintaining its effectiveness. Pharmaceutical composition

[0070] The present invention relates to a pharmaceutical composition, more precisely a radiopharmaceutical composition, comprising radioactive nanoparticles according to the invention, and a pharmaceutically acceptable excipient.

[0071] In certain embodiments, the pharmaceutical composition of the invention comprises nanoparticles comprising one or more α-emitting radionuclides and one or more [3+]-emitting radionuclides, in particular nanoparticles comprising a single α-emitting radionuclide, such as Ac or Ra, and a single [3+]-emitting radionuclide, such as 89Zr, and devoid of [3-]-emitting radionuclide.

[0072] In other embodiments, the pharmaceutical composition of the invention comprises nanoparticles comprising one or more α-emitting radionuclides and one or more [3-emitting radionuclides, in particular oo c 000 nanoparticles comprising a single a-emitting radionuclide, such as Ac or Ra, and a single 00 67 212 177 [3-] emitting radionuclide, such as Y, Cu, Pb or Lu., and devoid of [3+] emitting radionuclide.

[0073] In other embodiments, the pharmaceutical composition of the invention comprises nanoparticles comprising one or more α-emitting radionuclides, one or more [3- emitting radionuclides and one or more [3+ emitting radionuclides, in particular nanoparticles comprising a single α-emitting radionuclide, 225 223 80 such as Ac or Ra, a single emitting radionuclide [3+, such as Zr and a single emitting radionuclide [3-, such as 90Y, 67Cu, 212Pb or 177Lu.

[0074] The pharmaceutically acceptable excipient must be compatible with the intended mode of administration and compatible with the radioactive nanoparticle of the invention.

[0075] The pharmaceutical composition according to the invention is in particular formulated for intratumoral, intravenous or topical administration.

[0076] The pharmaceutical composition is therefore advantageously in the form of a suspension of nanoparticles in a pharmaceutically acceptable solvent, in particular in a saline solution. The composition may further comprise additives such as pH buffers, emulsifiers, wetting agents or combinations thereof.

[0077] Alternatively, the composition may be deposited on or incorporated into a medical device. Such a medical device is, for example, suitable for in situ application at the therapeutic target, or for topical application.

[0078] The composition of the invention is advantageously formulated so as to possess the activities making it possible to deliver the doses as specified above according to the quantity of composition administered to humans.

[0079] Each radionuclide encapsulated within the NPs of the invention is provided in the form of a solution of this radionuclide, in particular a solution of a salt of this radionuclide, having a predefined volume activity (in Bq / mL). The activity of each NPs therefore depends on the volume activity of this radionuclide solution, the half-life time of the radionuclide and the size of the NPs.

[0080] For example, the composition administered to the patient has an emission activity α ranging from 5 to 45 KBq, preferably from 15 KBq to 40 KBq.

[0081] For example, when the nanoparticles of the composition comprise one or more [3+] emitting radionuclides, the composition administered to the patient has a [3+] emission activity ranging from 30 MBq to 300 MBq, preferably from 35 KBq to 100 KBq.

[0082] For example, when the nanoparticles of the composition comprise one or more [3-] emitting radionuclides, the composition administered to the patient has a [3-] emission activity ranging from 1 GBq to 40 MBq, preferably from 1 GBq to 20 GBq. Use of the nanoparticles

[0083] - Therapeutic use #

[0084] The nanoparticles of the invention, or the pharmaceutical composition of the invention, are useful as a medicament, in particular for the prevention and / or treatment of cancer.

[0085] In other words, the present invention relates to the use of a radioactive nanoparticle according to the invention, or of a pharmaceutical composition according to the invention, as a medicament or for the manufacture of a medicament, in particular intended for the prevention and / or treatment of cancer.

[0086] In other words, the present invention relates to a method of preventing and / or treating cancer comprising administering at an effective dose to a person in need of a radioactive nanoparticle according to the invention, or a pharmaceutical composition according to the invention.

[0087] The nanoparticles of the invention, or the pharmaceutical composition of the invention, are particularly useful in radiotherapy, more particularly in targeted radiotherapy. Ionizing radiation a and ionizing radiation [3- are effective in radiotherapy and can destroy cancer cells. Thus, the nanoparticles of the invention are useful in radiotherapy, whether they comprise one or more emitting radionuclides [3- and / or [3+], because they necessarily contain one or more emitting radionuclides a.

[0088] In a particular embodiment, the nanoparticles of the invention useful in radiotherapy comprise one or more α-emitting radionuclides and one or more [3+]-emitting radionuclides. In this particular embodiment, they are in particular devoid of [3-]-emitting radionuclides.

[0089] In another embodiment, the nanoparticles of the invention useful in radiotherapy comprise one or more α-emitting radionuclides and one or more [3-]emitting radionuclides. In this particular embodiment, they are in particular devoid of [3+]emitting radionuclides. Preferably, they contain an α-emitting radionuclide, for example chosen from 225Ac and 223Ra, and a [3-]emitting radionuclide, for example 90Y, 67Cu, 212Pb or 177Lu. Such nanoparticles make it possible to deliver an effective dose of therapeutic radiation to the patient while ensuring their safety. Indeed, by combining these two types of radiation within the same nanoparticle, it is possible to reduce the dose of alpha radiation delivered, which is the most dangerous, and to achieve the necessary therapeutic dose with beta- radiation, which is less harmful to health.

[0090] In targeted radiotherapy, the nanoparticles of the invention will specifically target the cancer cells to be treated and accumulate therein. This targeting is carried out on the one hand by the size of the nanoparticles which will more easily accumulate at the level of the cancer cells. This is called passive targeting. This targeting can also be carried out using a targeting molecule grafted onto the surface of the nanoparticles. This is called active targeting.

[0091] In particular, the local injection of the nanoparticles of the invention at the level of the tumor makes it possible to release ionizing radiation which will specifically destroy the surrounding cancer cells and / or limit their propagation, while preserving healthy tissues.

[0092] In certain embodiments, the nanoparticles of the invention for use in the prevention and / or treatment of cancer are administered to a person in need thereof with the following activities:

[0093] - an activity of the emitting radionuclides ranging from 15 KBq to 40 KBq, and

[0094] - if applicable, an activity of the emitting radionuclides [3+ ranging from 35KBq to lOOKBq, and / or

[0095] - if applicable, an activity of the emitting radionuclides [3- ranging from 1 GBq to 20 GBq.

[0096] The cancers to be prevented and / or treated by the nanoparticles of the invention are, for example, chosen from pancreatic cancer, liver cancer, prostate cancer, breast cancer, ovarian cancer, vulvar cancer, vaginal cancer, brain cancer, skin cancer, neck cancer, head cancer, neuroendocrine tumors, leukemias and lymphomas. - Use in imaging #

[0097] Ionizing radiation [3+ is visible in imaging through the body. α and [3-] radiation is not visible in imaging.

[0098] Thus, only the nanoparticles of the invention comprising one or more α-emitting radionuclides and one or more [3+]-emitting radionuclides, or a pharmaceutical composition comprising such nanoparticles, are useful as an imaging agent.

[0099] The nanoparticles according to the invention useful in imaging may further comprise one or more emitting radionuclides [3-.

[0100] In a particular embodiment, the nanoparticles of the invention useful in imaging comprise one or more α-emitting radionuclides and one or more [3+]-emitting radionuclides, and are devoid of [3-]-emitting radionuclides. Preferably, they contain an α-emitting radionuclide, for example chosen from 225Ac and 223Ra, and a [3+]-emitting radionuclide, for example 89Zr.

[0101] In particular, this imaging agent is useful in PET (Positron Emission Tomography) imaging, which makes it possible to visualize radioactive nanoparticles comprising a [3+] emitting radionuclide within the body.

[0102] As stated previously, the nanoparticles of the invention will specifically accumulate at the level of cancer cells via passive and possibly active targeting. Consequently, the accumulation of the imaging agent according to the invention at the level of a cancerous tumor will make it possible to visualize the latter and to evaluate its size. The distribution of the NPs in the tumor will also be visualized.

[0103] In particular, the nanoparticles according to the invention useful as an imaging agent make it possible to locate a tumor within the body, in particular the human body. - Use in theranostics #

[0104] As indicated in the introduction, theranostics refers to a simultaneous use of imaging and therapy.

[0105] The nanoparticles of the invention comprising one or more α-emitting radionuclides and one or more [3+]-emitting radionuclides, or a pharmaceutical composition comprising such nanoparticles, are useful in theranostics. In other words, the nanoparticles of the invention comprising one or more α-emitting radionuclides and one or more [3+]-emitting radionuclides, or a pharmaceutical composition comprising such nanoparticles, can be used together for the imaging and treatment (and / or prevention) of cancerous tumors. In particular, such nanoparticles allow for effective detection and visualization of cancerous cells, while delivering a dose of therapeutic ionizing radiation sufficient to inhibit the growth of cancerous cells.

[0106] The nanoparticles according to the invention useful in theranostics may further comprise one or more emitting radionuclides [3-.

[0107] In a particular embodiment, the nanoparticles of the invention useful in theranostics comprise one or more α-emitting radionuclides and one or more [3+]-emitting radionuclides, and are devoid of [3-]-emitting radionuclides. Preferably, they contain an α-emitting radionuclide, for example chosen from 225Ac and 223Ra, and a [3+]-emitting radionuclide, for example 89Zr.

[0108] Use in theranostics of the nanoparticles of the invention makes it possible in particular to visualize the cancerous tumor, for example via PET, at the same time as the therapeutic action of the nanoparticles is exerted. It is thus possible to visualize the size of the cancerous tumor and to verify by imaging the cessation of the growth of the tumor or the reduction in the size of the tumor.

[0109] The nanoparticles of the invention useful jointly for the imaging and treatment (and / or prevention) of cancerous tumors are as described for use as an imaging agent. - Use in dosimetry#

[0110] The nanoparticles according to the invention comprising one or more α-emitting radionuclides and one or more [3+]-emitting radionuclides, or a pharmaceutical composition comprising such nanoparticles, are useful in dosimetry, i.e. for determining the dose of therapeutic radiation having reached the therapeutic target, i.e. the cancer cells.

[0111] In practice, visualization by imaging, typically by PET imaging, of the distribution of nanoparticles in the tumor makes it possible to quantify the dose of radiation absorbed by the tumor. Indeed, the intensity of the measured signal is a function of the number of photons visualized, and therefore of the number of radionuclides. [3+ emitters visualized in the tumor. It is possible from this data, and knowing the initial ratio of therapeutic radiation-emitting radionuclides / [3+ emitting radionuclides of the nanoparticles, to find the quantity of alpha-emitting radionuclide distributed to the tumor. Indeed, the advantage of the nanoparticle of the present invention is to integrate the two types of radionuclides in a single nanoparticle, so that it is certain that the two radionuclides have the same distribution within the body. By visualizing the distribution of the [3+ emitting radionuclides, the distribution of the therapeutic radiation-emitting radionuclides, and therefore the absorbed dose, is automatically obtained. By difference with the initially administered quantity, it is also possible to deduce the quantity of radiation distributed to healthy tissues and therefore to measure the possible toxicity of the nanoparticles.

[0112] The nanoparticles according to the invention comprising one or more α-emitting radionuclides and one or more [3+]-emitting radionuclides, or a pharmaceutical composition comprising such nanoparticles, can therefore be used in a method of dosimetry of therapeutic radiation having reached the therapeutic target comprising: i. administration of the nanoparticles into the body, the nanoparticles having a known ratio of therapeutic radiation-emitting radionuclides to [3+] emitting radionuclides; ii. visualization by imaging of nanoparticles, in particular by PET imaging, and determination of the intensity of the signal emitted by the emitting radionuclides [3+ iii. quantification of the activity of the emitting radionuclides [3+ using the intensity of the signal determined in step ii) iv. quantification of the activity of therapeutic radiation-emitting radionuclides using the ratio of therapeutic radiation-emitting radionuclides / [3+]-emitting radionuclides.

[0113] The nanoparticles according to the invention useful in dosimetry may further comprise one or more emitting radionuclides [3-. In this case, the therapeutic radiations correspond to the a radiations and the radiations

[0114] In a particular embodiment, the nanoparticles of the invention useful in dosimetry comprise one or more α-emitting radionuclides and one or more [3+]-emitting radionuclides, and are devoid of [3-]-emitting radionuclides. Preferably, they contain an α-emitting radionuclide, for example chosen from 225Ac and 223Ra, and a [3+]-emitting radionuclide, for example 89Zr. In this case, the therapeutic radiation corresponds to the α-radiations only. Process for preparing nanoparticles

[0115] The present invention also relates to a method for preparing the nanoparticles of the invention comprising one or more α-emitting radionuclides and one or more [3-emitting radionuclides, comprising the following steps: a. Sol-gel preparation of nanoparticles based on porous material, b. Radiolabeling of the nanoparticles from step a) with one or more emitting radionuclides a and one or more emitting radionuclides [3, c. Coating of the radioactive nanoparticles from step b) with a metal shell.

[0116] The radionuclides included in the nanoparticles and the metal shell are as described above.

[0117] The sol-gel process of step a) is well known to those skilled in the art. Typically, when the porous material is porous silica, the sol-gel process is carried out by placing in aqueous solution, preferably in the presence of a base, a silicon alkoxide, such as tetraethyl orthosilicate (TEOS). The silica-based nanoparticles are then formed by centrifugation of the resulting solution.

[0118] Step b) of radiolabeling is carried out by physical adsorption of the radionuclides on the nanoparticles resulting from step a). In a first variant, each radionuclide is added separately and successively. Thus, if the nanoparticle comprises an α-emitting radionuclide and a β-emitting radionuclide, a first radionuclide will be adsorbed on the nanoparticle and then in a subsequent step, the second radionuclide will be adsorbed by the core of the nanoparticle. In the case where the nanoparticle comprises several radionuclides of the same type, for example several α-emitting radionuclides, each will be adsorbed separately and successively by the core of the nanoparticle. Advantageously, the order of adsorption of the radionuclides depends on their half-life. Radionuclides having a longer half-life will be adsorbed before radionuclides having a shorter half-life.

[0119] In a second variant, the radionuclides are added simultaneously.

[0120] Typically, a solution of a radionuclide, in particular a radionuclide salt, is added to a suspension of nanoparticles. The nanoparticles are, for example, suspended in a buffer solution at neutral pH. The mixture is heated, for example between 50°C and 80°C, then centrifuged to recover the radiolabeled nanoparticles. An ultrasonication step of the mixture can also be carried out to improve T adsorption. This protocol is repeated for each radionuclide to be adsorbed by the core of the nanoparticle.

[0121] The methodology of coating step c) depends on the nature of the metal envelope applied to the surface of the nanoparticle. Those skilled in the art will know Depending on the nature of the metal envelope, apply the appropriate protocol to carry out the coating.

[0122] According to a particular example, the coating step c) is carried out by suspending the radiolabeled nanoparticles in a solution containing a solvent, for example an alcohol such as ethanol, and a metal or a metal oxide. For example, if the metal shell consists of titanium dioxide, the solution comprises titanium butoxide. The nanoparticles are left suspended in this solution for the time necessary for the coating to be carried out. The suspension time also depends on the half-life time of the nanoparticles. The nanoparticles are then centrifuged and recovered.

[0123] The method for preparing the nanoparticles may comprise an intermediate step a') between steps a) and b) of storing the nanoparticles. Indeed, nanoparticles based on porous material, for practical reasons, can be produced on a large scale, then stored for a significant time and / or transported, for example to the injection site.

[0124] On the other hand, steps b) and c) are preferably carried out successively in a short period of time depending on the half-life of the adsorbed radionuclides.

[0125] Preferably, once step c) is completed, the radioactive nanoparticles will be administered to the patient in need within a very short period of time depending on the half-life of the adsorbed radionuclides.

[0126] For example, the half-life of 223Ra is 11.4 days and that of 89Zr is 78 hours (3 days). In a nanoparticle comprising Ra and Zr, the half-life of 89Zr is therefore limiting and will determine the durations in which step c) and then administration to the patient must be carried out. EXAMPLES

[0127] 1. Synthesis of nanoparticles 1. Synthesis of silica-based nanoparticles# #

[0128] SiO2 nanoparticles (NPs) are prepared using the sol-gel method. To do this, 8.75 mL of ethanol (99.9%) and 2.4 mL of milli-Q water are mixed for 5 minutes. Then, 65 pL of 99% tetraethylorthosilicate (TEOS) and 390 pL of ammonium hydroxide are added. The resulting mixture is stirred for 2 hours. The resulting solution is then transferred into 2 mL centrifuge tubes to separate the SiO2 nanoparticles by centrifugation at a rotation speed of 12,000 rpm for 5 min. A washing step is performed by centrifugation at 12,000 rpm for 5 minutes, once with ethanol and once with milli-Q water. Finally, the formed SiO2 NPs are dried in an oven at 70°C for 15 min. Radiolabeling with ~ Ra and ~ Zr

[0129] Radiolabeling was performed by physical adsorption of 223Ra by the synthesized SiO2 NPs. Initially, 3 mg of SiO2 NPs were suspended in 1 mL of a solution

[0130] 10 mM HEPES buffer (pH 7.2), then a solution containing [223Ra] and 89 Zr. and 2.5 qL of 2M Na2CO3 solution were added to the tube.

[0131] The mixture was incubated at 70°C for 60 min with a rotation speed of 1000 rpm.

[0132] solution was suspended by ultrasonication for 15min to enhance the adsorption of the radionuclide. Then, the labeled NPs were centrifuged at 12,000 rpm for 5 min and washed twice with milli-Q water. During the different steps, the supernatants were collected and the radioactivity was measured using a gamma counter.

[0133] Since the initial activity of the radionuclide solution added to the SiO2 NP suspension is known, it is possible to calculate the adsorption efficiency of the radionuclides by measuring the remaining activity at the end of the step. This efficiency can be recalculated after the coating step to verify that the latter does not result in a significant loss of activity. 1 • Coating of SiO 2 Ra- — Zr NPs with a TiO 2 layer

[0134] After the radiolabeling process, the SiO2-223Ra-89Zr nanoparticles were coated with a layer of TiO2. For this, 3 mg of SiO2-Ra-Zr NPs are transferred into a 1.5 mL solution containing a mixture of titanium butoxide (Ti(C4HQO)4) and ethanol in a volumetric ratio of 1:75. The solution is then subjected to ultrasound to ensure the suspension of the particles. After 15 min, the solution is left at room temperature for 24 h without stirring, which allows the formation of the SiO2-Ra-Zr-TiO2 nanoparticles. In order to remove heavy aggregates, centrifugation at 800 rpm for 1 min is performed. The supernatant containing the SiO2-Ra-Zr-TiO2 nanoparticles is collected and transferred to a new container to be centrifuged at 12,000 rpm for 5 min. A wash at 12,000 rpm for 3 min is carried out once with ethanol and once with milli-Q water.

[0135] After their separation and coating, each radionuclide showed an adsorption capacity of approximately 60%, determined by means of a calibration curve previously obtained by measuring the activity of radium and zirconium using a gamma counter for different known concentrations of each radionuclide. 1. Coating of SiO 2 NPs with a TiO 2 layer

[0136] The same protocol as described in paragraph 1.3 is used to coat non-radiolabeled SiO2 nanoparticles (from the protocol of paragraph 1.1) in order to study their physicochemical properties as well as those of the uncoated SiO2 NPs.

[0137] Scanning electron microscopy (SEM) analysis was performed to study the morphology of SiO2 nanoparticles. The SEM image (Figure 1a) shows the presence of SiO2 nanoparticles with a homogeneous sphere shape. This confirms that the synthesis conditions resulted in regular and uniform nanoparticles. It is important to note that scanning electron spectroscopy mainly provides morphological information, such as particle shape and size. For a better understanding of the properties of the obtained SiO2 NPs, transmission electron microscopy (TEM) analysis is performed. [Fig.2] presents TEM images of nanoparticles, where the size of SiO2 NPs is approximately 150-220 nm. A high-resolution TEM study was performed to determine the thickness of the TiO2 layer (see [Fig.3]).These results confirm the formation of a very thin layer of TiO2 (between Inm and 10nm), sufficient to fill the pores and prevent the release of radionuclides.

[0138] The presence of Ti on the surface of SiO2-TiO2 NPs is confirmed by the EDX spectrum in Figure 1b. This confirms the formation of a TiO2 layer around the SiO2 core.

[0139] In order to better understand the surface composition and binding environment of NPs

[0140] SiO2-TiO2, X-ray photoelectron spectroscopy (XPS) analysis was performed. The full spectra revealed the presence of Si and O elements for SiO2 nanoparticles, as well as Si, O and Ti elements for SiO2-TiO2 nanoparticles (Fig. 4a). These results indicate the success of the synthesis method as well as the coating of the NPs with TiO2 on the silica cores. The high-resolution XPS spectra of Si 2p, Ti 2p and O 1s energy levels are shown in Fig. 4b-d. The Si 2p spectrum of SiO2 NPs shows a single peak (104.3eV) corresponding to the Si-O-Si bond. The same peak is detected in the spectra of SiO2-TiO2 NPs, in addition to another peak at 102.2 eV, both corresponding to the Si-O-Ti binding energy. The Ti 2p spectrum showed the peaks at 458.7 and 464.6 eV, corresponding to the Ti 2p3 / 2 orbital and Ti 2pl / 2 orbital, respectively. This shows the presence of Ti4+ oxidation state.The XPS spectrum of O 1s for the SiO2 sample shows a peak at 532.8 eV, which is assigned to Si-O. In the case of SiO2-TiO2, the spectrum is deconvoluted into three peaks due to its asymmetry (Figure 4b). The first one at 530.3 eV was assigned to . TiO2. The second peak at 532.6 eV was attributed to SiO2. The weaker peak at 530.9 eV was attributed to the Si-O-Ti binding energy. Thus, these results suggest that TiO2 nanoparticles were deposited on the surface of SiO2 nanoparticles, forming a coating layer. Radiolabeling with ~ Zr

[0141] The same radiolabeling protocol described in paragraph 1.2 and then coating described in paragraph 1.3 are implemented to radiolabel SiO2 NPs with the radionuclide 89Zr with an initial activity of 3MBq, then coat them with a layer of TiO2.

[0142] The adsorption efficiency after incubation is 95%. After the two washing steps, only a 3% loss was detected. Upon TiO2 coating, only 5% of the activity was lost. This coating step did not result in any additional significant loss during the subsequent cleaning step. The radiolabeled NPs were used to study the release at different time intervals. After 10 days, a very minimal percentage of 0.2% was observed to be released. Therefore, this study highlights the ability of SiO2-TiO2 nanoparticles to effectively encapsulate zirconium radionuclide, with high adsorption rates and minimal activity losses during the washing and coating steps. These results confirm that these nanoparticles are promising for applications such as medical imaging. 1. In vivo tumor imaging performance#

[0143] This study aims to evaluate the consequences of injecting SiO2-TiO2 nanoparticles, labeled with radioactive isotopes Zr (for imaging) and Ra (for therapy), into mice. The objective of this study is to explore the feasibility of combining imaging and tumor growth inhibition by simultaneously using these radioactive markers. For this, one mouse (SI) received an injection of SiO2-89Zr-TiO2 nanoparticles containing a dose of 125.8 kBq, while another mouse (S2) received an injection of SiO2-Zr-Ra-TiO2 nanoparticles with an activity of 66.6 kBq for zirconium and 13.32 kBq for radium.

[0144] Positron emission tomography (PET) imaging was performed immediately after administration of radiolabeled samples for both mice, and after a delay of 24 hours for SI and 90 hours for S2.

[0145] The results demonstrate that the use of two types of radiolabeled NPs, namely Zr and Zr and Ra, allows active imaging of the tumor and detection of tumor lesions. In addition, sufficient accumulation of these NPs at the tumor site was observed ([Fig.5]). It is therefore envisaged that the nanoparticles S1O2-89 Zr-223 Ra-TiO2 constitute a powerful platform for tumor imaging and treatment when combined together.

Claims

Claims

1. Radioactive nanoparticle of core / shell type comprising: - a core based on a porous material, comprising one or more α-emitting radionuclide(s) and one or more β-emitting radionuclide(s) [3, and - a metal shell.

2. Radioactive nanoparticle according to claim 1, characterized in that the radionuclides are adsorbed on the porous material.

3. Radioactive nanoparticle according to claim 1 or 2, characterized in that the envelope is made of a material chosen from metals, metal oxides, metal alloys, their mixtures and their combinations.

4. Radioactive nanoparticle according to claim 3, characterized in that the metal envelope comprises, in particular is made of, titanium oxide.

5. Radioactive nanoparticle according to any one of claims 1 to 4, characterized in that one or more emitting radionuclide(s) a is (are) chosen from the group consisting of Ac, Ra, 21 *At, 212Bi, 227Th, 224Ra, 221Fr and 213Po.

6. Radioactive nanoparticle according to any one of claims 1 to 5, characterized in that the one or more emitting radionuclide(s) [3 is (are) independently chosen from the group consisting of emitting radionuclide(s) [3+, emitting radionuclide(s) [3- and a combination thereof.

7. Radioactive nanoparticle according to any one of claims 1 to 6, characterized in that one or more emitting radionuclide(s) [3 is (are) chosen from the group consisting of emitting radionuclide(s) [3+, in particular 89Zr, 18F, nC, 13N, 150.68 Ga, 82Rb, 64Cu, 124I and 207Bi.

8. Radioactive nanoparticle according to any one of claims 1 to 6, characterized in that one or more emitting radionuclide(s) [3 is (are) chosen from the group consisting of emitting radionuclide(s) [3-, in particular 131I, 89Sr, 153Sm, 32P, 90Y, 166Ho, 177Lu, 188Re, 169Er, 145Pm, 67Cu and 212Pb.

9. A pharmaceutical composition comprising a radioactive nanoparticle as described in any one of claims 1 to 8 and a pharmaceutically acceptable excipient.

10. Radioactive nanoparticle according to any one of claims 1 to 8, for use as a medicament.

11. Radioactive nanoparticle according to any one of claims 1 to 8, for use in the treatment and / or prevention of cancer, in particular pancreatic cancer, liver cancer, prostate cancer, breast cancer, ovarian cancer, vulvar cancer, vaginal cancer, brain cancer, skin cancer, neck cancer, head cancer, neuroendocrine tumors, leukemias and lymphomas.

12. Radioactive nanoparticle according to claim 7, for its use as an imaging agent, in particular for PET imaging.

13. Radioactive nanoparticle according to claim 7, for its joint use in: - imaging and - treatment and / or prevention of tumors.

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