Combined therapy of nanoparticles and radiopharmaceuticals

Abstract

The present invention relates to high-Z element-containing nanoparticles for use in a method of treating tumors by radiopharmaceutical therapy in a subject in need of treatment of tumors by radiopharmaceutical therapy, said method comprising the combined administration of an effective amount of said high-Z element-containing nanoparticles and a therapeutic radiopharmaceutical comprising an effective amount of a radionuclide, wherein said high-Z element-containing nanoparticles contain an element having an atomic Z number of 40 or more, preferably 50 or more, and wherein said nanoparticles have an average hydrodynamic diameter of 20 nm or less, for example 1 to 10 nm, preferably 2 to 8 nm.

Description

Background Art

[0001] The principle of radiotherapy is to induce irreparable DNA lesions in tumor cells, leading to cell death. Half of cancer patients receive conventional external radiotherapy (X-RT) that irradiates tumors from outside the body. This approach is suitable for treating localized tumors or oligometastases but is generally not applicable to diffuse or metastatic diseases due to unacceptable irradiation of healthy tissues. With several compounds recently approved by the FDA and EMA, radiopharmaceutical therapy, also called targeted radionuclide therapy (TRT), has emerged as a safe and effective systemic treatment modality that irradiates all tumor sites (Sgouros et al., 2020).

[0002] In TRT, radiolabeled cancer-binding molecules (e.g., antibodies, peptides) are injected into patients. After circulating in the bloodstream, they recognize and bind to tumor cells, irradiating them locally. TRT enables the use of β-particles and very powerful α-particles or Auger electron emitters (AEEs). Similar to the X-rays used in X-RT, β-particles are low linear energy transfer (LET) particles that cause "simple DNA damage" such as single-strand and double-strand breaks (SSB, DSB) or base damage (e.g., thymidine glycol). In contrast, α-particles and to a lesser extent AEEs are high LET particles that cause irreparable complex or clustered DNA damage and are attractive candidates for overcoming radioresistance. Unlike X-RT, TRT irradiation is protracted and delivered at low dose and low dose rate, reducing side effects in bone marrow and circulating blood cells. For these reasons, the radiobiology of X-RT cannot be directly extrapolated to TRT (Pouget et al., 2011; Pouget et al., 2021).

[0003] Ovarian cancer (OC) is the most lethal gynecological malignancy today and the eighth most frequent cancer-related cause of death among women worldwide. Histologically, 90% of OC originates from the malignant transformation of epithelial cells. In this context, the most aggressive OC arises from the fallopian tube epithelium, known as high-grade serous ovarian cancer (HGSOC). Disease progression without clinical signs and symptoms in most cases leads to late diagnosis (stages III / IV) when it spreads intraperitoneally in the form of peritoneal carcinomatosis (PC). The treatment of PC consists of tumor debulking surgery to remove macroscopic lesions and subsequent intraperitoneal platinum-based chemotherapy. Many women respond to this treatment approach, but in 70–90% of cases, the disease recurs and remains confined intraperitoneally.

[0004] In the 1980s, Sugarbaker proposed the combined use of tumor debulking surgery and intraperitoneal hyperthermic chemotherapy to treat residual lesions in selected patients with peritoneal carcinomatosis (Sugarbaker, 2009). Intraperitoneal hyperthermic chemotherapy increases the survival rate of patients with primary recurrent disease and is used today as primary or secondary treatment. However, it is not recommended outside of clinical trials due to one of the main drawbacks of intraperitoneal hyperthermic chemotherapy, which is its morbidity (Goodman et al., 2016). Therefore, there is an urgent need to suppress the residual lesions that cause recurrence in patients. For this type of metastatic and diffuse disease, conventional radiotherapy cannot be applied because of the high risk of damage to surrounding healthy tissues. A TRT-based strategy using radiolabeled antibodies specifically directed against tumor nodules offers a new treatment opportunity for treating HGSOC (Pouget et al., 2015).

[0005] Several studies using rodents have shown that radioimmunotherapy (RIT) is an effective adjuvant after tumor debulking surgery for peritoneal carcinomatosis (Koppe et al., 2005; Aarts et al., 2007; Aarts et al., 2008; Muller et al., 2012; Seidl et al., 2011; Milenic et al., 2004; Andersson et al., 2003; Elgqvist et al., 2005). For IP RIT in ovarian cancer patients, several antibodies (against MUC1, CA-125, TAG72 and gp38) have been conjugated to 4β-emitting radionuclides (Pouget et al.). Based on previous promising results (Meredith et al., 2007; Alvarez et al., 2002; Epenetos et al., 2002; Hird et al., 1993), the efficacy of conventional chemotherapy was 90 A phase III randomized multi-center trial comparing IP injection of Y-labeled HMGF1 murine mAb (anti-MUC1) was conducted (Verheijen et al., 2006). However, although peritoneal recurrence was significantly delayed, no improvement in survival was observed after RIT. SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0006] Strategies based on TRT are very promising, but the therapeutic index still needs to be improved. In particular, harmful side effects on healthy tissues (e.g., bone marrow) limit dose escalation. This need is even more pronounced in situations where tumors, such as in the ovary, show radioresistance.

[0007] Therefore, there still exists a need to overcome the drawbacks of the prior art and provide an improved TRT-based protocol. MEANS FOR SOLVING THE PROBLEM

[0008] This disclosure is partially derived from the surprising finding by the inventors that the use of nanoparticles according to this disclosure in combination with a therapeutic radiopharmaceutical compound in a TRT protocol increases the effectiveness of TRT. Surprisingly, the combination therapy enables tumor co-localization of the therapeutic radiopharmaceutical compound and the nanoparticles sufficient to enhance the effect of the therapeutic radiopharmaceutical compound.

[0009] Thus, such nanoparticles can be used in combination with a therapeutic radiopharmaceutical to enhance the effectiveness of targeted radiation therapy or to maintain its effectiveness while reducing the dose of the therapeutic radiopharmaceutical administered.

[0010] Accordingly, embodiment E1 of the present disclosure is a high-Z element-containing nanoparticle for use in a method of treating a tumor by radiopharmaceutical therapy in a subject in need thereof, the method comprising the combined administration of an effective amount of the high-Z element-containing nanoparticle and a therapeutic radiopharmaceutical comprising an effective amount of a radionuclide, the high-Z element-containing nanoparticle comprising an element having an atomic Z number of 40 or more, preferably 50 or more, and the nanoparticles having an average hydrodynamic diameter of 20 nm or less, such as 1 to 10 nm, preferably 2 to 8 nm.

[0011] Embodiment E2 of the present disclosure relates to a nanoparticle for use in the method according to embodiment E1, wherein the nanoparticle enhances the therapeutic effect of the radiopharmaceutical.

[0012] Embodiment E3 of the present disclosure relates to a nanoparticle for use according to any of embodiments E1 or E2, wherein the high-Z element is selected from among heavy metals, and more preferably Au, Ag, Pt, Pd, Sn, Ta, Zr, Tb, Tm, Ce, Dy, Er, Eu, La, Nd, Pr, Lu, Yb, Bi, Hf, Ho, Pm, Sm, In, and Gd, and mixtures thereof.

[0013] Embodiment E4 of the present disclosure is such that the radionuclide is 177 Lu,161 Tb, 186 Re, 131 I, 90 Y, 225 Ac / 213 Bi, 223 Ra, 212 Pb / 212 Bi, 227 Th, 211 At, 97 Ru, 103 Pd, 67 Ga, 195m Pt, 193m Pt, 125 I, 111 Relates to nanoparticles for use according to any of embodiments E1 to E3, selected from Tb, Re, I, Y, Ac / Bi, Ra, Pb / Bi, Th, At, Ru, Pd, Ga, Pt, Pt, I, In and mixtures thereof.

[0014] Embodiment E5 of the present disclosure relates to nanoparticles for use according to any one of embodiments E1 to E3, wherein the effective amount of the radiopharmaceutical is comprised between 0.5 MBq and 100 GBq, preferably between 1 MBq and 100 GBq.

[0015] Embodiment E6 of the present disclosure relates to nanoparticles for use according to any of embodiments E1 to E4, wherein the radionuclide is linked to a cancer targeting moiety.

[0016] Embodiment E7 of the present disclosure relates to nanoparticles for use according to embodiment E5, wherein the cancer targeting moiety is an antibody, a peptide or a small molecule ligand.

[0017] Embodiment E8 of the present disclosure relates to nanoparticles for use according to either embodiment E6 or E7, wherein the cancer targeting moiety is selected from the following - Anti-HER2 antibodies such as trastuzumab, pertuzumab, or ibritumomab (also called ibritumomab tiuxetan and commercialized under the trademark Zevalin®), anti-EGFR antibodies such as cetuximab or panitumumab, anti-CD20 antibodies such as rituximab or Zevalin®, anti-CD33 antibodies such as rituximab, anti-CD37 antibodies such as otrexup (TRU-016), mAB 37.1 (BI 836826) or IMGN529 (K7153A-DM1), anti-AMHRII antibodies such as mulrentamab, or anti-TYRP1 / gp75 antibodies such as IMC-20D7S, - Somatostatin analogs such as octreotide (DOTATOC) or octreotate (DOTATATE), or - PSMA small molecule ligands such as 617 ligand, I&T ligand, R2 ligand or MIP-1095 ligand,

[0018] Embodiment E9 of the present disclosure is such that the therapeutic radiopharmaceutical is 177 a Lu-anti-HER2 antibody such as Lu-trastuzumab 177 a Lu-anti-HER2 antibody, 177 a Lu-somatostatin analog such as Lu-dotatate 177 a Lu-somatostatin analog, 177 a Lu-PSMA ligand, 90 a Y-rituximab or 90 a Y-anti-CD20 antibody such as Y-ibritumomab 90 a Y-anti-CD20 antibody, 212 a Pb-anti-HER2 antibody, 177 relates to nanoparticles for use as described in any of Embodiments E1 to E8, selected from Lu-anti-CD37 antibodies.

[0019] Embodiment E10 of the present disclosure is such that the therapeutic radiopharmaceutical is 131 I or 223 Ra, and relates to nanoparticles for use as described in any of Embodiments E1 to E4.

[0020] Embodiment E11 of the present disclosure relates to nanoparticles for use according to any of Embodiments E1 to E10, wherein the nanoparticles are administered to a subject by a divided administration method.

[0021] Embodiment E12 of the present disclosure relates to nanoparticles for use according to any of Embodiments E1 to E11, wherein the divided administration method of the nanoparticles includes a divided administration amount of the nanoparticles of 2 to 10 for each dose of the therapeutic radiopharmaceutical administered to the subject.

[0022] Embodiment E13 of the present disclosure relates to nanoparticles for use according to any of Embodiments E1 to E12, wherein the subject is a subject who cannot receive the standard effective dose of radiopharmaceutical treatment.

[0023] Embodiment E14 of the present disclosure relates to nanoparticles for use according to any of Embodiments E1 to E13, wherein the tumor is a radiation-resistant tumor.

[0024] Embodiment E15 of the present disclosure relates to nanoparticles for use according to any of Embodiments E1 to E14, wherein the tumor is selected from peritoneal tumors including primary peritoneal tumors and secondary peritoneal tumors, neuroendocrine tumors including gastrointestinal pancreatic neuroendocrine tumors and pheochromocytomas or paragangliomas (PPGL), prostate tumors, neuroblastomas, meningiomas, lymphomas, Merkel cell carcinomas, breast cancers, renal cell tumors, and salivary gland cancers.

Brief Description of the Drawings

[0025]

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Mode for Carrying Out the Invention

[0026] The present disclosure is in part based on the surprising finding that certain nanoparticles having radiosensitizing properties co-localize with therapeutic radiopharmaceutical compounds and substantially increase the effectiveness of TRT, as demonstrated by the inventors. Without wishing to be bound by any particular theory, it is believed that the advantageous effects of the treatment methods of the present disclosure are related to at least the following two characteristics of these nanoparticles: (i) They contain a complex with a high-Z element, typically a high-Z cation having radiosensitizing properties, (ii) They have a small average hydrodynamic diameter, thereby enabling passive targeting to cancer cells. In the present disclosure, "passive targeting to cancer cells" and "passive targeting" refer to the phenomenon in which the nanoparticles of the present invention accumulate in tumor tissue without being functionalized for this purpose and, in particular, without being linked to any cancer targeting moiety. The inventors do not wish to be bound by any theory, but this phenomenon in which the high-Z element-containing nanoparticles according to the present invention exhibit passive targeting to cancer cells may, at least in part, be explained by the enhanced permeability and retention (EPR) effect. The EPR effect is a phenomenon in which certain molecules, macromolecular compounds or nanoparticles tend to accumulate in tumor tissue. This may be due, at least in part, to the fact that the endothelial cells of the blood vessels perfusing the tumor are somewhat loose, so that circulating objects diffuse more easily, and / or the fact that the tumor is not sufficiently drained.

[0027] The inventors have surprisingly shown that the nanoparticles of the present invention reach tumor tissue only by passive targeting and thus enhance the effect of the therapeutic radiopharmaceutical, even though the nanoparticles are not functionalized to target specific tissues.

[0028] While not wishing to be bound by any theory, the inventors believe that the efficacy of the combination therapy is due to the co-localization of the tumor with the therapeutic radiopharmaceutical compound and the radiation sensitizing effect of the high-Z element contained in the nanoparticles on the radionuclide containing the therapeutic radiopharmaceutical, and that such radiation sensitizing effect is mediated by ferrotosis. This aspect will be described in more detail below.

[0029] In the present disclosure, the term "radiation sensitization" will be readily understood by those skilled in the art and generally refers to the process of increasing the sensitivity of cancer cells to radiation therapy (e.g., photon radiation, electron radiation, proton radiation, alpha radiation, heavy ion radiation). The high-Z element used herein is an element having an atomic Z number greater than 40, for example, greater than 50.

[0030] In certain embodiments, the high-Z element is selected from among heavy metals, and more preferably, Au, Ag, Pt, Pd, Sn, Ta, Zr, Tb, Tm, Ce, Dy, Er, Eu, La, Nd, Pr, Lu, Yb, Bi, Hf, Ho, Pm, Sm, In, and Gd, and mixtures thereof. The high-Z element is preferably a cationic element contained within the nanoparticles as an oxide and / or chalcogenide or halide, or as a complex with a chelating agent such as an organic chelating agent.

[0031] The size distribution of the nanoparticles is measured using a commercially available particle sizer such as a Malvern Zetasizer Nano-S particle sizer based on PCS (photon correlation spectroscopy), for example.

[0032] For the purposes of the present disclosure, the term "average hydrodynamic diameter" or "average diameter" is intended to mean the harmonic mean of the diameters of the particles. The method for measuring this parameter is also described in standard ISO 13321:1996. Nanoparticles with an average hydrodynamic diameter of less than, for example, 20 nm, particularly between 1 and 10 nm, more preferably between 1 and 8 nm, or for example between 2 and 8 nm, or typically around 5 nm are suitable for the methods disclosed herein. In particular, they have been shown to provide excellent passive targeting in tumors after intravenous injection and rapid renal excretion (and thus low toxicity).

[0033] In one embodiment, the nanoparticles contain a high-Z element in an amount exceeding 10% by weight, preferably less than 50% by weight, based on the total weight of the nanoparticles. In certain embodiments, the nanoparticles contain Gd in an amount between 10% and 50%, preferably between 10% and 20%, for example about 15% ± 1% by weight, based on the total weight of the nanoparticles.

[0034] According to one embodiment, the nanoparticles contain, as a high-Z element in the nanoparticles, at least 50% by weight of gadolinium (Gd), dysprosium (Dy), lutetium (Lu), bismuth (Bi), or holmium (Ho) or a mixture thereof (relative to the total weight of the high-Z elements in the nanoparticles), for example, at least 50% by weight of gadolinium (Gd). In a particularly preferred embodiment, the nanoparticles used in the methods of the present disclosure are gadolinium-based nanoparticles.

[0035] In certain embodiments, the high-Z element is a cationic element complexed with an organic chelating agent selected from, for example, carboxylic acids, amines, thiols, or phosphonate group-containing chelating agents.

[0036] In preferred embodiments, the nanoparticles further comprise a biocompatible coating in addition to the high-Z element and optionally a chelating agent. Such biocompatible agents include, but are not limited to, biocompatible polymers such as polyethylene glycol, polyethylene oxide, polyacrylamide, biopolymers, polysaccharides, or polysiloxanes.

[0037] In certain embodiments, the nanoparticles are from 10 to 5000 mM -1 ·s -1 selected to have a relaxivity r1 (at 37° C. and 1.4 T) and / or a Gd weight ratio of at least 5%, such as 5% to 30%.

[0038] In one specific embodiment, nanoparticles having a very small hydrodynamic diameter, such as between 1 and 10 nm, preferably between 2 and 8 nm, are nanoparticles that include a chelate of a high-Z element such as a chelate of a rare earth element. In certain embodiments, the nanoparticles include a chelate of gadolinium or bismuth. In certain embodiments that can be combined with any of the previous embodiments, the high-Z element comprising the nanoparticles comprises: · a polyorganosiloxane · a chelating agent covalently bonded to the polyorganosiloxane, · a high-Z element complexed by the chelating agent

[0039] As used herein, the term “chelating agent” refers to one or more chemical moieties capable of complexing one or more metal ions. Exemplary chelating agents include, but are not limited to, 1,4,7-triazacyclononane triacetic acid (NOTA), 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), 1,4,7-triazacyclononane-1-glutaric acid-4,7-diacetic acid (NODAGA), ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), cyclohexyl-1,2-diaminetetraacetic acid (CDTA), ethylene glycol-0,0'-bis(2-aminoethyl)-N,N,N',N'-tetraacetic acid (EGTA), N,N-bis(hydroxybenzyl)-ethylenediamine-N,N'-diacetic acid (HBED), triethylenetetraaminehexaacetic acid (TTHA), hydroxyethyldiaminetriacetic acid (HEDTA), 1,4,8,11-tetraazacyclotetradecane-N,N',N",N"'-tetraacetic acid (TETA), and 1,4,7,10-tetraaza-1,4,7,10-tetra-(2-carbamoylmethyl)-cyclododecane (TCMC), and 1,4,7,10-tetraazacyclododecane, 1-(glutaric acid)-4,7,10-triacetic acid (DOTAGA), desferrioxamine (DFO).

[0040] In a preferred embodiment, the chelating agent is selected from the following:

Chemical formula

[0041] In certain embodiments, preferably in combination with the previous embodiments, the chelate of the rare earth element is a chelate of gadolinium and / or bismuth, preferably DOTA or DOTAGA chelated Gd 3+ and / or Bi 3+ and is a chelate thereof.

[0042] In a specific and preferred embodiment, the ratio of the high-Z element per nanoparticle, for example, the ratio of the rare earth element per nanoparticle, such as gadolinium (optionally chelated with DOTAGA), is 3 to 100, preferably 5 to 50, for example 5 to 20, typically around 10. At such ratios, the nanoparticles have excellent relaxation and contrast enhancement properties for MR imaging even when used with an MR-Linac having a low magnetic field strength such as a 0.35 T or 0.5 T MR-Linac.

[0043] In certain embodiments, the hybrid nanoparticles are of the core-shell type. Core-shell type nanoparticles consisting of a core of rare earth oxide and an optionally functionalized polyorganosiloxane matrix are known (see in particular WO2005 / 088314, WO2009 / 053644).

[0044] The nanoparticles can be further functionalized with molecules that enable targeting of the nanoparticles to specific tissues. The agents can be attached to the nanoparticles by covalent bonds or can be captured by non-covalent bonds, for example, by encapsulation or hydrophilic / hydrophobic interactions, or using chelating agents. In one specific embodiment, the use consists of hybrid nanoparticles: - A polyorganosiloxane (POS or PS) matrix containing rare earth cations Mn+, where n is an integer from 2 to 4, optionally in the form of a metal oxide and / or oxyhydroxide, and optionally combined with doping cations Dm+, where m is an integer from 2 to 6, and D is preferably a rare earth metal other than M, actinide and / or transition elements; - A chelate covalently bonded to the POS via a covalent bond -Si-C- - The Mn+ cations, and optionally the Dm+ cations, are complexed by the chelate.

[0045] In a preferred embodiment, the nanoparticles are not functionalized with molecules that enable targeting of the nanoparticles to specific tissues, particularly tumors.

[0046] In this embodiment, as will be described in detail below, the nanoparticles reach the tumor only by passive targeting. In the case of a core-shell type structure, the POS matrix forms a surface layer surrounding the metal cation-based core. Its thickness ranges from 0.5 to 10 nm and can be 25 to 75% of the total volume. The POS matrix acts as a protection of the core against the external medium (especially protection against hydrolysis) and optimizes the properties of the contrast agent (such as luminescence). It also enables the functionalization of the nanoparticles through the grafting of chelating agents and targeting molecules.

[0047] Ultra-fine nanoparticles for use in the disclosed treatment methods In a particularly preferred embodiment, the nanoparticles are gadolinium-chelated polysiloxane nanoparticles of the following formula,

Chemical formula

[0048] In a preferred embodiment involving complete dissolution of the metal oxide core, these nanoparticles obtained according to the method described above do not contain a core of metal oxide encapsulated by at least one coating. Details regarding the synthesis of these nanoparticles are shown below.

[0049] This top-down synthesis method typically results in observed sizes between 1 - 8 nm, more specifically between 2 - 8 nm. The term used herein next is ultrafine nanoparticles.

[0050] Alternatively, another "one-pot" synthesis method is described below for preparing the ultrafine nanoparticles having an average diameter of less than 10 nm, for example 1 - 8 nm, typically between 2 - 6 nm. Further details regarding these ultrafine or core-free nanoparticles, the processes for synthesizing them and their uses are described in patent applications WO2011 / 135101, WO2018 / 224684 or WO2019 / 008040 which are incorporated by reference.

[0051] Process for obtaining a preferred embodiment of the nanoparticles for use in the disclosed therapeutic methods Generally, those skilled in the art will be able to easily manufacture the nanoparticles used according to the disclosure. Specifically, pay attention to the following elements: For core-shell type nanoparticles, based on a core of lanthanide oxide or oxyhydroxide, it can be used in the manufacturing process using alcohol as a solvent, as described, for example, in P. Perriat et al., J. Coll. Int. Sci, 2004, 273, 191; O. Tillement et al., J. Am. Chem. Soc., 2007, 129, 5076 and P. Perriat et al., J. Phys. Chem. C, 2009, 113, 4038. For the POS matrix, several techniques can be used that are derived from those initiated by Stoeber (Stoeber, W; J. Colloid Interf Sci 1968, 26, 62). As described by Louis et al. (Louis et al., 2005, Chemistry of Materials, 17, 1673 - 1682) or in international application WO2005 / 088314, the processes used for coating can also be utilized.

[0052] In fact, the synthesis of ultrafine nanoparticles is described, for example, in Mignot et al., Chem. Eur. J. 2013, 19, 6122 - 6136: Typically, core / shell type precursor nanoparticles are formed with a lanthanide oxide core (via a modified polyol route) and a polysiloxane shell (via sol / gel), and these objects have a hydrodynamic diameter of, for example, about 5 - 10 nm. Thus, lanthanide oxide cores of very small size (adjustable below 10 nm) can be produced in alcohol by one means of the processes described in the following publications: P. Perriat et al., J. Coll. Int. Sci, 2004, 273, 191; O. Tillement et al., J. Am. Chem. Soc., 2007, 129, 5076 and P. Perriat et al., J. Phys. Chem. C, 2009, 113, 4038.

[0053] These cores can be coated with a layer of polysiloxane, for example, according to the protocols described in C. Louis et al., Chem. Mat., 2005, 17, 1673 and O. Tillement et al., J. Am. Chem. Soc., 2007, 129, 5076.

[0054] A chelating agent specific to the target metal cation (e.g., DOTAGA for Gd 3+ ) is grafted onto the surface of the polysiloxane; although it is also possible to insert a part of it inside the layer, the control of the formation of polysiloxane is complicated, and a simple external grafting gives a sufficient ratio of grafts for these very small sizes.

[0055] The nanoparticles can be separated from the synthesis residues by dialysis or tangential filtration, for example, on a membrane containing pores of an appropriate size.

[0056] The core is destroyed by dissolution (e.g., by changing the pH or introducing complexing molecules into the solution). This destruction of the core enables the diffusion and rearrangement of the polysiloxane layer (by a slow corrosion or disintegration mechanism), and ultimately it becomes possible to obtain a polysiloxane object with a complex morphology. Its characteristic dimension is on the order of the thickness of the polysiloxane layer, that is, much smaller than the objects generated so far.

[0057] Therefore, by removing the core, it becomes possible to reduce the particle size from approximately 5 - 10 nm in diameter to a size less than 8 nm, for example, between 2 - 8 nm. The number of M per nanoparticle size can be evaluated by the M / Si atomic ratio measured by EDX. Typically, this number of M per ultrafine nanoparticle can be included between 5 - 50.

[0058] In one specific embodiment, the nanoparticles according to the disclosure include a chelating agent having an acid function, such as DOTA or DOTAGA. The acid function of the nanoparticles is activated, for example, using EDC / NHS (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide / N-hydroxysuccinimide) in the presence of an appropriate amount of a targeting molecule. The nanoparticles grafted in this way are then purified, for example, by tangential filtration.

[0059] Alternatively, the nanoparticles according to the present disclosure include at least one hydroxysilane or alkoxysilane that is negatively charged at physiological pH and at least one chelating agent selected from polyaminopolycarboxylic acids, - at least one hydroxysilane or alkoxysilane that is neutral at physiological pH, and / or - at least one hydroxysilane or alkoxysilane that is positively charged at physiological pH and contains an amino functional group, and can be obtained, or can be obtained, by a synthesis method (the "one-pot synthesis method") that includes a mixture therewith, where: - The molar ratio A of neutral silane to negatively charged silane is defined as follows: 0 ≦ A ≦ 6, preferably 0.5 ≦ A ≦ 2; - The molar ratio B of positively charged silane to negatively charged silane is defined as follows: 0 ≦ B ≦ 5, preferably 0.25 ≦ B ≦ 3; - The molar ratio C of neutral and positively charged silanes to negatively charged silane is defined as follows: 0 < C ≦ 8, preferably 1 ≦ C ≦ 4. According to a more specific implementation of such a one-pot synthesis method, the method includes at least one alkoxysilane that is negatively charged at physiological pH (the alkoxysilane is selected from APTES-DOTAGA, TANED, CEST, and mixtures thereof), - at least an alkoxysilane that is neutral at physiological pH (the alkoxysilane is selected from TMOS, TEOS, and mixtures thereof), and / or - including mixing with APTES positively charged at physiological pH, where: - the molar ratio A of neutral silane to negatively charged silane is defined as follows: 0 ≦ A ≦ 6, preferably 0.5 ≦ A ≦ 2; - the molar ratio B of positively charged silane to negatively charged silane is defined as follows: 0 ≦ B ≦ 5, preferably 0.25 ≦ B ≦ 3; - the molar ratio C of neutral and positively charged silanes to negatively charged silane is defined as follows: 0 < C ≦ 8, preferably 1 ≦ C ≦ 4.

[0060] According to a particular embodiment, one - pot synthesis method involves APTES - DOTAGA negatively charged at physiological pH, - at least one alkoxysilane neutral at physiological pH (said alkoxysilane being selected from TMOS, TEOS and mixtures thereof), and / or - APTES positively charged at physiological pH, where: - the molar ratio A of neutral silane to negatively charged silane is defined as follows: 0 ≦ A ≦ 6, preferably 0.5 ≦ A ≦ 2; - the molar ratio B of positively charged silane to negatively charged silane is defined as follows: 0 ≦ B ≦ 5, preferably 0.25 ≦ B ≦ 3; - the molar ratio C of neutral and positively charged silanes to negatively charged silane is defined as follows: 0 < C ≦ 8, preferably 1 ≦ C ≦ 4.

[0061] AGuIX nanoparticles

[0062] In a more particularly preferred embodiment, the gadolinium - chelated polysiloxane - based nanoparticles are ultrafine AGuIX nanoparticles of the following formula:

Chemical formula

[0063] Pharmaceutical formulations of nanoparticles for use according to the disclosed methods

[0064] When used as a medicine, the composition containing the high-Z nanoparticles for use provided herein can be administered in the form of a pharmaceutical formulation of a suspension of the nanoparticles. These formulations can be prepared as described herein or elsewhere and can be administered by various routes depending on whether local or systemic treatment is desired and on the area to be treated.

[0065] In certain embodiments, the pharmaceutical formulations for use as described herein contain, as an active ingredient, a suspension of high-Z-containing nanoparticles as provided herein, in combination with one or more pharmaceutically acceptable carriers (excipients). In preparing the pharmaceutical formulations provided herein, the nanoparticle composition can, for example, be mixed with an excipient or diluted by an excipient. When the excipient acts as a diluent, it can be a solid, semi-solid, or liquid material, which acts as a vehicle, carrier, or medium for the nanoparticle composition. Accordingly, the pharmaceutical preparation can be in the form of a powder, lozenge, elixir, suspension, emulsion, solution, syrup, aerosol (as a solid or in a liquid medium), sterile injectable solution, sterile packaged powder, and the like.

[0066] In certain embodiments, the pharmaceutical preparation for use as described herein is a sterile lyophilized powder, for example, contained in a pre-filled vial that is reconstituted in an aqueous solution for intravenous injection. In certain embodiments, the lyophilized powder contains, as an active ingredient, an effective amount of the high-Z-containing nanoparticles, typically gadolinium chelated polysiloxane-based nanoparticles, more specifically the AguIX nanoparticles described herein. In certain specific embodiments, the lyophilized powder contains either about 200 mg to 15 g per vial, for example, 280 - 320 mg of AguIX per vial, typically 300 mg of AguIX per vial, or about 800 mg to 1200 mg, for example, 1 g of AguIX per vial.

[0067] Such a powder can further contain one or more additional excipients, particularly CaCl2, for example, 2 - 5 mg of CaCl2 per g of AguIX, typically 4.4 mg of CaCl2.

[0068] The lyophilized powder may be reconstituted in an aqueous solution, typically water for injection. Accordingly, in certain embodiments, the pharmaceutical solution for use in accordance with the present disclosure is an injectable solution containing, as an active ingredient, an effective amount of the high-Z-containing nanoparticles, typically gadolinium chelated polysiloxane-based nanoparticles, more specifically the AguIX nanoparticles described herein. For example, the injectable solution used in the method disclosed herein is a solution of gadolinium chelated polysiloxane-based nanoparticles, typically 50 - 150 mg / mL, for example, 80 - 120 mg / mL, typically 100 mg / mL of AguIX nanoparticles, optionally containing one or more additional pharmaceutically acceptable excipients, for example, 0.2 - 0.6 mg / mL of CaCl2, typically 0.44 mg / mL of CaCl2.

[0069] In certain embodiments, the pharmaceutical formulation for use as described herein is an aqueous solution contained in a vial, which contains, as an active ingredient, an effective amount of said high-Z-containing nanoparticles, typically gadolinium chelated polysiloxane-based nanoparticles, more specifically AguIX nanoparticles as described herein. In certain embodiments, the vial contains about 1-5 g of AguIX, typically about 2 g - 3 g of AguIX, for example 2.5 g of AguIX. In some embodiments, the aqueous solution can be used to prepare an injectable solution as described above or is an injectable solution as described above.

[0070] The treatment method of the present disclosure

[0071] The present disclosure relates to high-Z element-containing nanoparticles for use in a method of treating tumors by radiopharmaceutical therapy, said method comprising administering in a subject in need thereof, in combination, an effective amount of high-Z element-containing nanoparticles and a therapeutic radiopharmaceutical comprising an effective amount of a radionuclide. As used herein, the term "high-Z element-containing nanoparticles" means the nanoparticles described in the previous section. The present disclosure relates to a method of treating tumors in a subject in need thereof by radiopharmaceutical therapy, which comprises co-administering to the subject a therapeutic radiopharmaceutical containing an effective amount of high-Z element-containing nanoparticles and an effective amount of a radionuclide as disclosed herein, according to the dosing regimens disclosed herein.

[0072] The present disclosure also relates to the use of high-Z element-containing nanoparticles and the use of a therapeutic radiopharmaceutical containing a radionuclide as disclosed herein in the preparation of a medicament for the treatment of tumors in a subject in need thereof by radiopharmaceutical therapy. Here, in particular, an effective amount of high-Z element-containing nanoparticles and an effective amount of the therapeutic radiopharmaceutical will be co-administered according to the dosing regimens disclosed herein.

[0073] According to the present disclosure, the term "radiopharmaceutical therapy", also referred to as "targeted radionuclide therapy" (abbreviated as TRT), "targeted radiopharmaceutical therapy", "molecular radiotherapy", "radioimmunotherapy", or "targeted radiotherapy" means the treatment of neoplastic diseases with radiopharmaceuticals containing therapeutic radionuclides. In radiopharmaceutical therapy, radiation is delivered systemically or locally to tumors using a therapeutic radiopharmaceutical containing a radionuclide capable of delivering direct ionizing radiation to tumor cells. Ionizing radiation accumulates energy that damages or destroys the cells (so-called "target effect" on the target tissue) in the treated area by damaging their genetic material, as a result of which these cells can no longer continue to grow. Typically, the ionizing radiation is alpha particles, beta particles, and Auger electrons. Radiation can also damage non-irradiated cells at short distances (bystander effect) or long distances (systemic or immune effect) of the irradiated cells through cell-cell communication.

[0074] According to the present disclosure, the term "treat" or "treatment" means (1) inhibiting a disease; for example, inhibiting a disease, illness, or disorder in an individual who is experiencing or showing the medical condition or symptoms of the disease, illness, or disorder (i.e., preventing further progression of the pathology and / or symptomatology); and (2) improving a disease; for example, improving a disease, illness, or disorder in an individual who is experiencing or showing the medical condition or symptoms of the disease, illness, or disorder (i.e., reversing the medical condition and / or symptoms), for example reducing the severity of the disease, or reducing or alleviating one or more of the symptoms of the disease, or one or more of the above. In particular, with respect to the treatment of tumors, the term "treatment" can refer to inhibiting the growth of tumors, reducing the size of tumors, or completely destroying tumors.

[0075] According to the present disclosure, the term "effective amount" or "therapeutically effective amount" of an active ingredient (e.g., a therapeutic radiopharmaceutical), alone or in combination with another active ingredient (e.g., in combination with nanoparticles containing high-Z elements), refers to the amount of the active ingredient that will induce a biological or medical response in a subject, e.g., improve a medical condition, alleviate a disease, slow or delay the progression of a disease, or prevent it.

[0076] According to the present disclosure, the effective amount of a therapeutic radiopharmaceutical refers to the amount of the therapeutic radiopharmaceutical administered to a patient for treating a tumor in the context of radiopharmaceutical therapy, for example, by inducing regression or elimination of the tumor by destroying the structure of the tumor and / or killing tumor cells. The effective amount of such a therapeutic radiopharmaceutical is generally expressed in terms of activity (Mega Becquerel, MBq or Giga Becquerel, GBq) and may also be referred to as the "total injected activity". Such an effective amount is generally designed to deliver an appropriate radiation dose (Gray, Gy) to the tumor.

[0077] According to the present disclosure, the effective amount of a therapeutic radiopharmaceutical can be administered in a fractionated dosing regimen, i.e., the total dose of the therapeutic radiopharmaceutical (i.e., the total injected activity) is divided into several smaller doses called "fractionated doses of the therapeutic radiopharmaceutical" and administered to the patient in multiple dosing cycles over a period of, for example, several days or months. Alternatively, the therapeutic radiopharmaceutical may be administered as a single bolus dose. The effective amount of a therapeutic radiopharmaceutical depends on several factors such as the dosing regimen, the therapeutic radiopharmaceutical, the body weight of the patient, the location and severity of the tumor.

[0078] In one embodiment, the effective amount of the therapeutic radiopharmaceutical administered to a subject is between 0.5 MBq and 100 GBq, preferably between 10 MBq and 50 GBq.

[0079] In one embodiment, the therapeutic radiopharmaceutical is administered in a fractionated regimen having a dosing cycle of 4 to 20 times, and each fractionated dose has an activity contained between 0.5 MBq and 100 GBq, preferably between 1 MBq and 10 GBq, more preferably between 2 MBq and 8 GBq.

[0080] In certain embodiments, the therapeutic radiopharmaceutical is 177 Lu-DOTATATE, and the effective amount of the therapeutic radiopharmaceutical is administered in a fractionated regimen having 2 to 6 dosing cycles, preferably 4 dosing cycles, and each fractionated dose has an activity contained between 1 and 10 GBq, preferably between 5 GBq and 10 GBq, more preferably between 7 and 9 GBq, for example having an activity of 7.4 GBq. For example, 177 Lu-DOTATATE can be administered in a fractionated regimen having 4 dosing cycles, where each dose having activity is contained between 7 and 8 GBq, typically 7.4 GBq.

[0081] In one embodiment, the effective amount of the therapeutic radiopharmaceutical is designed to deliver a radiation dose (gray, Gy) of at least 50 mGy, preferably at least 500 mGy, more preferably at least 1 Gy to the tumor. It should be noted that radionuclide imaging techniques result in an exposure of less than 50 mGy, while Gy is achieved in the treatment using radionuclides.

[0082] According to the present disclosure, the effective amount of the nanoparticles refers to the amount of nanoparticles that enables enhancing the therapeutic effectiveness of the therapeutic amount of the therapeutic radiopharmaceutical administered to a patient for treating a tumor. The effective amount of the nanoparticles may depend on several factors such as the type, effective amount, and dosing regimen of the therapeutic radiopharmaceutical administered to the patient.

[0083] According to the present disclosure, an effective amount of nanoparticles is preferably administered in a divided dosing regimen, i.e., for each dose of the therapeutic radiopharmaceutical administered to a patient, the total dose of nanoparticles is divided into several smaller nanoparticle doses, each herein referred to as a "nanoparticle divided dose", and, for example, administered to the patient in multiple dosing cycles over a period of 4 to 72 hours before or after administration of each dose of the therapeutic radiopharmaceutical.

[0084] According to the present disclosure, as used herein, the terms "patient" and "subject" are used interchangeably to mean any member of the animal kingdom, including mammals and invertebrates. For example, mice, rats, other rodents, rabbits, dogs, cats, pigs, cows, sheep, horses, primates, fish, and humans. Preferably, the subject is a mammal, more preferably a human, and includes, for example, a subject having a tumor.

[0085] According to the present disclosure, the terms "co - administration", "concomitant administration", or "simultaneous administration" mean the combined administration of at least two therapeutic agents, where a first therapeutic agent, typically a therapeutic radiopharmaceutical compound, is administered to the same subject that requires it, simultaneously or within a time interval, with a second therapeutic agent, typically nanoparticles containing a high - Z element (preferably AguIX), and, in particular, according to the dosing regimens disclosed herein, the time interval allows the combination partners to exhibit a cooperative or synergistic effect for treating a tumor. It does not mean that the therapeutic agents must be administered simultaneously and / or formulated to be delivered together, although these delivery methods are within the scope described herein. As used herein, the terms "co - administration", "concomitant administration", and "simultaneous administration" are the opposite of monotherapy, which involves the administration of a single therapeutic agent. The therapeutic radiopharmaceutical can be administered simultaneously with, before, or after one or more other additional treatments or therapeutic agents. The terms also mean encompassing treatment regimens in which at least one or both agents are administered in a divided regimen. The terms also mean encompassing treatment regimens in which the agents are not necessarily administered by the same route of administration.

[0086] In one embodiment, the combination administration for use according to the present invention induces oxidative cell death in tumor cells.

[0087] In one embodiment, the combination administration for use according to the present invention reduces the antioxidant capacity of tumor cells and / or increases the accumulation of reactive oxygen species (ROS) in tumor cells, resulting in oxidative cell death of tumor cells.

[0088] Therapeutic radiopharmaceutical

[0089] According to the present disclosure, radiopharmaceutical therapy can be performed using any type of therapeutic radiopharmaceutical.

[0090] In the present disclosure, the terms "therapeutic radiopharmaceutical containing a radionuclide", "therapeutic radiopharmaceutical" and "targeted radiopharmaceutical", "radiopharmaceutical compound" or "radiopharmaceutical", which are used interchangeably herein, mean a pharmaceutical compound intended to be administered to a subject in need thereof, said pharmaceutical compound containing a radionuclide capable of emitting ionizing radiation, and in particular, capable of delivering ionizing radiation directly and specifically to tumor cells, the microenvironment of tumor cells, and / or the organs harboring tumor cells.

[0091] According to the present disclosure, the term "radionuclide" refers to any radioactive isotope of an element that emits one or more ionizing radiations selected from beta-minus particles, alpha-minus particles, and Auger electrons.

[0092] In one embodiment, the radionuclide is 177 Lu, 161 Tb, 186 Re, 131 I, 90 Y, 225 Ac / 213 Bi, 223 Ra, 212 Pb / 212 Bi, 227Th , 211 At, 97 Ru, 103Pd, 67 Ga, 195m Pt, 193m Pt, 125 I, 111 selected from In and mixtures thereof. In one embodiment, the radionuclide is 177 Lu, 161 Tb, 186 Re, 131 I, 90 Y, and a beta particle emitter selected from mixtures thereof. In one embodiment, the radionuclide is 225 Ac / 213 Bi, 223 Ra, 212 Pb / 212 Bi, 227Th , 211 At, and an alpha particle emitter selected from mixtures thereof. 3 In one embodiment, the radionuclide is 97 Ru, 103 Pd, 67 Ga, 195m Pt, 193m Pt, 125 I, 111 In and an Auger electron emitter selected from mixtures thereof.

[0093] 177 Lu, 131 I, 111 Some of the radionuclides described herein, such as Lu, I, In, etc., in addition to the above ionizing radiation, emit gamma / X-rays or beta plus particles and can thus be monitored by SPECT imaging (single photon emission computed tomography).

[0094] Targeting of the radionuclide to the tumor can be provided by the cancer targeting moiety or can be inherent to the radionuclide, as detailed below. In the present disclosure, the therapeutic radiopharmaceutical containing the radionuclide is different from the nanoparticle containing high-Z elements.

[0095] A radionuclide linked to a cancer targeting moiety

[0096] In one embodiment, the radionuclide is linked to the cancer targeting moiety. According to the present disclosure, the term "linked" means that the cancer targeting moiety and the radionuclide are chemically linked by a covalent bond, optionally via a linker moiety, or that the cancer targeting moiety comprises a chelating moiety and the radionuclide is complexed to the chelating moiety of the cancer targeting moiety. In one embodiment, the therapeutic radiopharmaceutical has the formula N-(X-)M, where N is a radionuclide, M is a cancer targeting moiety, and X is any chelating moiety (Ch) or linker moiety (L). In one embodiment, the radionuclide N is complexed to the cancer targeting moiety via a chelating moiety (Ch). In another embodiment, the radionuclide is covalently bound to the cancer targeting moiety M via a linker moiety (L). According to the present disclosure, the term "cancer targeting moiety" refers to a moiety that provides targeting to tumor cells.

[0097] In one embodiment, the cancer targeting moiety exhibits the ability to recognize and bind to one or more sites or antigens, such as cell surface receptors, that are specific to tumor cells of the tumor microenvironment or of an organ having tumor cells.

[0098] The cancer targeting moiety can be an antibody or a binding fragment thereof, a peptide or a small molecule ligand, and preferably binds specifically to a tumor antigen or a tumor-associated antigen.

[0099] According to the present disclosure, "specifically binds to" or "binds specifically to" or "targets" means that a cancer targeting moiety (e.g., an antibody) binds to the antigen with a higher affinity than it binds to an irrelevant antigen. Preferably, such an affinity is at least 10-fold greater, more preferably at least 100-fold greater, and most preferably at least 1000-fold greater than the affinity of the cancer targeting moiety for an irrelevant antigen. In certain embodiments, "specifically binds to" means that the cancer targeting moiety binds to a given target and does not bind to other antigens.

[0100] As used herein, the term "tumor antigen" or "cancer antigen" means any protein produced in tumor cells having an abnormal sequence or structure due to mutation and capable of acting as a tumor antigen. Since mutations in oncogenes and tumor suppressor genes leading to abnormal protein production are the cause of tumors, such abnormal proteins are called tumor-specific antigens. Examples of tumor antigens include abnormal products of the ras and p53 genes. Also, "tumor antigen" means a "tumor-associated antigen" which is a protein having a mutation in another gene unrelated to tumor formation that may lead to the synthesis of an abnormal protein. The term also encompasses other cellular antigens that may be natural, but which can be targeted by anti-cancer agents to eliminate cells expressing such antigens.

[0101] In certain embodiments, the cancer targeting moiety is an antibody that specifically binds to a tumor antigen or a tumor-associated antigen.

[0102] According to the present disclosure, the term "antibody" refers to any whole antibody molecule of any isotype (such as IgG, IgA, IgM, IgE, etc.) that includes an immunoglobulin binding domain that specifically binds to an antigen such as a tumor antigen or a tumor - associated antigen. The term "antibody" includes polyclonal, monoclonal, or other purified preparations of antibodies and recombinant antibodies. The term "antibody - binding fragment" refers to a fragment of a whole antibody that retains the property of specifically binding to an antigen. Antibodies can be fragmented using conventional techniques, and the fragments are screened for their interaction with the antigen of interest. Thus, the term "fragment" includes proteolytically cleaved or recombinantly prepared segments of antibody molecules that can specifically bind to a given antigen. Non - limiting examples of such proteolytic and / or recombinant fragments include Fab, F(ab’)2, Fab’, Fv, and single - chain antibodies (scFv) that include V[L] and / or V[H] domains linked by a peptide linker. ScFv can bind covalently or non - covalently to form antibodies with two or more binding sites.

[0103] In one embodiment, the cancer - targeting moiety specifically binds to one or more cancer antigens selected from HER2 (human epidermal growth factor receptor 2), EGFR (epidermal growth factor receptor), GRBR (gastrin - releasing peptide receptor), CD20, CD33, CD37, somatostatin receptor, prostate - specific membrane antigen (PSMA), AMHRII (anti - Müllerian hormone receptor type 2), and TYRP1 / gp75 (tyrosinase - related protein 1).

[0104] In one embodiment, the cancer - targeting moiety specifically binds to at least one antigen of the tumor microenvironment, such as a cancer - associated fibroblast (CAF) antigen like fibroblast activation protein α (FAP), or an immune checkpoint antigen such as cytotoxic T - lymphocyte - associated protein 4 (CTLA - 4), programmed death 1 receptor (PD - 1), or its ligand PD - L1.

[0105] In one embodiment, the cancer targeting moiety is an anti-HER2 antibody such as trastuzumab, pertuzumab, or ibritumomab (also known as ibritumomab tiuxetan and commercialized under the trademark Zevalin®), an anti-EGFR antibody such as cetuximab or panitumumab, an anti-CD20 antibody such as rituximab or Zevalin®, an anti-CD33 antibody such as lintuzumab, an anti-CD37 antibody such as otrexup (TRU-016), mAB 37.1 (BI 836826) or IMGN529 (K7153A-DM1), an anti-AMHRII antibody such as mulrentamab, or an anti-TYRP1 / gp75 antibody such as IMC-20D7S. In one embodiment, the cancer targeting moiety is a somatostatin analog such as octreotide (DOTATOC) or octreotate (DOTATATE) that targets the SSTR2 receptor.

[0106] In one embodiment, the cancer targeting moiety is a PSMA small molecule ligand such as the 617 ligand, I&T ligand, R2 ligand, or MIP-1095 ligand.

[0107] In one embodiment, the therapeutic radiopharmaceutical is 177 such as Lu-trastuzumab 177 a Lu-anti-HER2 antibody, 177 an Lu-somatostatin analog such as Lu-DOTATATE that targets the SSTR2 receptor 177 a Lu-somatostatin analog, 177 a Lu-PSMA ligand such as 90 Y-rituximab or 90 such as Y-ibritumomab 90 a Y-anti-CD20 antibody, 212 a Pb-anti-HER2 antibody, and 177 is selected from Lu-anti-CD37 antibodies.

[0108] a radionuclide having an intrinsic target

[0109] In another embodiment, the therapeutic radiopharmaceutical consists of a radionuclide having an inherent target, i.e., a radionuclide having an inherent affinity for tumor cells, the microenvironment of tumor cells, or the organ harboring tumor cells. In that embodiment, the therapeutic radiopharmaceutical does not have a cancer targeting moiety as described above. Such a therapeutic radiopharmaceutical can be selected from 131 iodine-131 ( 223 I) or radium-223 (

[0110] Iodine-131 accumulates naturally in the thyroid and can be used as a therapeutic radiopharmaceutical for treating thyroid tumors.

[0111] Radium-223 accumulates naturally in bone and can be used as a therapeutic radiopharmaceutical for treating bone metastases from prostate or breast cancer.

[0112] Nanoparticles

[0113] In one embodiment, the therapeutic radiopharmaceutical containing the radionuclide and the nanoparticles do not have the same targeting properties.

[0114] In one embodiment, the nanoparticles are not functionalized with molecules that enable targeting of the nanoparticles to specific tissues, particularly tumors.

[0115] In one embodiment, the nanoparticles are not conjugated to a cancer targeting moiety as described herein.

[0116] In one embodiment, the nanoparticles reach tumors, particularly tumor cells, only by passive targeting. In one embodiment, the nanoparticles are sufficiently co-localized with the therapeutic radiopharmaceutical containing the radionuclide, such that the nanoparticles have a radiosensitizing effect on the radiopharmaceutical, preferably being tumor specific.

[0117] In one embodiment, the nanoparticles have a radiosensitizing effect on the therapeutic radiopharmaceutical containing the radionuclide, preferably being tumor specific.

[0118] In one embodiment, the nanoparticles have a radiosensitizing effect on the lysosomes of tumor cells.

[0119] In one embodiment, the radiosensitizing effect is sufficient to produce one or more of (i) enhanced lysosome disruption in tumor cells, (ii) enhanced iron release in tumor cells, (iii) enhanced ROS production in tumor cells, (iv) enhanced lipid peroxidation in tumor cells, and / or (v) oxidative cell death in tumor cells.

[0120] In one embodiment, the radiosensitizing action is at least partially mediated by ferroptosis.

[0121] In one embodiment, the radiosensitizing effect is sufficient to induce oxidative cell death in tumor cells.

[0122] In one embodiment, the nanoparticles are AGuiX nanoparticles as described in the previous section.

[0123] Administration regimen

[0124] The present disclosure relates to a method comprising co - administration of a therapeutic radiopharmaceutical comprising high - Z element - containing nanoparticles and a radionuclide, and to high - Z element - containing nanoparticles for use in a method of treating a tumor by radiopharmaceutical therapy in a patient in need thereof. The inventors have shown that such co - administration, particularly when the nanoparticles are administered to a subject in a fractionated dosing regimen, results in increased tumor regression compared to administration of only the therapeutic radiopharmaceutical containing the radionuclide. The advantageous effects of the co - administration by the treatment method of the present disclosure are thought to be as follows: (i) Enhancing the therapeutic efficacy of the therapeutic radiopharmaceutical administered to the patient for treating the tumor, (ii) Enabling a reduction in the effective amount of the therapeutic radiopharmaceutical that needs to be administered to the patient for treating the tumor, thereby reducing the radiation - induced toxicity to the patient.

[0125] In one embodiment, the nanoparticles containing high-Z elements and the therapeutic radiopharmaceutical are administered simultaneously, separately, or sequentially. In certain embodiments, the therapeutic radiopharmaceutical is administered before or after the nanoparticles.

[0126] In one embodiment, the nanoparticles are administered to the subject in a divided dosing regimen. In one embodiment, the therapeutic radiopharmaceutical is administered to the subject in a divided dosing regimen. In one embodiment, both the nanoparticles and the therapeutic radiopharmaceutical are administered to the subject in a divided dosing regimen. That is, the therapeutic radiopharmaceutical is administered to the subject in a divided dosing regimen, and for each administration of the therapeutic radiopharmaceutical, the nanoparticles are administered in a divided dosing regimen.

[0127] In one embodiment, the nanoparticle divided dosing regimen is designed to enhance the therapeutic activity of the dose of the therapeutic radiopharmaceutical for at least the duration of the effective half-life of the therapeutic radiopharmaceutical dose. In the present disclosure, the effective half-life (T eff ) of the therapeutic radiopharmaceutical dose can be calculated taking into account the radioactive decay of the radionuclide (T eff ) = (1 / T phys ) + (1 / T biol ) using the formula 1 / T Phys ) and the biological half-life (T biol ) of the radiopharmaceutical. In French, the term effective half-life (T eff ) is called "periode effective".

[0128] In one embodiment, the nanoparticle divided dosing regimen includes 2 to 10 divided administrations of the nanoparticles for each dose of the therapeutic radiopharmaceutical administered to the subject. In one embodiment, the nanoparticle administration is divided between 24 hours and 72 hours after the administration of the dose of the therapeutic radiopharmaceutical.

[0129] In one embodiment, the divided dosing regimen of the nanoparticles is administered on the first, second, third, fourth and / or fifth day after administration of the therapeutic radiopharmaceutical. In one embodiment, the divided dosing regimen of the nanoparticles is administered on the first, second, third, fourth and / or fifth day after administration of each dose of the therapeutic radiopharmaceutical. In a preferred embodiment, the divided dosing regimen of the nanoparticles is administered once a day or once every two days.

[0130] The first divided dose of the nanoparticles can be administered before or after first administering the therapeutic radiopharmaceutical to a subject in need thereof.

[0131] In one embodiment, the first divided dose of the nanoparticles is administered 5 minutes, 15 minutes, 30 minutes, 45 minutes, 1 hour, 2 hours, 4 hours, 6 hours, 12 hours, 24 hours, 48 hours or 72 hours, preferably between 24 hours and 72 hours, after administration of the dose of the therapeutic radiopharmaceutical.

[0132] In one embodiment, the first divided dose of the nanoparticles is administered 5 minutes, 15 minutes, 30 minutes, 45 minutes, 1 hour, 2 hours, 4 hours, 6 hours, 12 hours, 24 hours, 48 hours or 72 hours, preferably between 24 hours and 72 hours, after first administering the dose of the therapeutic radiopharmaceutical to a subject in need thereof.

[0133] In one embodiment, the divided doses of the nanoparticles are administered with an elapsed time between two divided doses, for example an elapsed time of 6 hours, within 4 hours to 48 hours, preferably within 4 hours to 12 hours, more preferably within 4 hours to 10 hours.

[0134] In one embodiment, the nanoparticle divided dosing regimen is designed according to the following: (i) To avoid excessive toxicity, the tumor removal and / or retention in the kidney of the nanoparticles, and (ii) The time the therapeutic radiopharmaceutical is retained at the tumor site.

[0135] While not wishing to be bound by any theory, when the therapeutic radiopharmaceutical is a radionuclide linked to an antibody, the inventors believe that the dose of the therapeutic radiopharmaceutical is sequestered in the tumor from 24 to 168 hours after administration to the patient, and maximally between 24 and 72 hours. In that case, the inventors believe it is desirable to fractionate the nanoparticle administration between 24 and 72 hours after administration of the dose of the therapeutic radiopharmaceutical in order to maximize the potential of the dose of the therapeutic radiopharmaceutical.

[0136] Patient Selection

[0137] In one embodiment, the present disclosure relates to a method of treating a tumor in a subject in need thereof by radiopharmaceutical therapy, the method comprising administering nanoparticles comprising a high-Z element in combination with a dose of a therapeutic radiopharmaceutical, wherein the nanoparticles are capable of reducing the dose of the therapeutic radiopharmaceutical in a subject in need of its administration as compared to the dose administered to a subject treated by radiopharmaceutical therapy alone.

[0138] In one embodiment, the method of the present disclosure is applied to a subject who cannot receive the standard effective dose of targeted radionuclide therapy. In a preferred embodiment, the method of the present disclosure is applied to a subject having a radiation-resistant tumor. Radiation-resistant tumors include, but are not limited to, renal tumors, melanomas, thyroid tumors, colorectal tumors.

[0139] In one embodiment, the therapeutic activity of the therapeutic radiopharmaceutical is due to both the biological action of the cancer-targeting moiety and the effect of the ionizing radiation of the radionuclide.

[0140] Tumor to be Treated

[0141] According to the present disclosure, the term "tumor" means an abnormal tumor of tissue where the growth of the tumor exceeds that of normal tissue and is less regulated than the growth of normal tissue. Tumors can be "benign" or "malignant" depending on the degree of cell differentiation (including morphology and function), growth rate, local invasion, and metastatic properties. "Benign tumors" are generally well-differentiated, grow significantly more slowly than malignant tumors, and remain localized to the primary site. Furthermore, benign tumors do not have the ability to invade, penetrate, or metastasize to distant sites. Some "benign" tumors may later develop into malignant tumors, which may be due to additional genetic changes in subpopulations of tumor cells within the tumor, and these tumors are referred to as "precancerous tumors". An exemplary precancerous tumor is a teratoma. In contrast, "malignant tumors" are generally poorly differentiated (anaplastic), exhibit significantly rapid growth accompanied by progressive invasion, penetration, and destruction of surrounding tissue. Furthermore, malignant tumors often have the ability to metastasize to distant sites. The terms "malignant tumor" and "cancer" are used interchangeably herein. In certain embodiments, the tumor to be treated expresses a tumor antigen that is specifically targeted by a radiopharmaceutical compound for use in the disclosed methods. Exemplary cancers include acoustic neuroma; adenocarcinoma; adrenal cancer; anal cancer; angiosarcoma (e.g., lymphangiosarcoma, lymphangioendothelioma, angiosarcoma); appendiceal cancer; benign monoclonal propionibacteria; biliary tract cancer (e.g., bile duct cancer (e.g., cholangiocarcinoma)); bladder cancer; breast cancer (e.g., breast adenocarcinoma, breast papillary carcinoma, breast cancer, breast medullary carcinoma); brain tumor (e.g., meningioma, glioblastoma, glioma (e.g., astrocytoma, oligodendroglioma), medulloblastoma); bronchial cancer; carcinoid tumor; cervical cancer (e.g., cervical cancer (e.g., cervical adenocarcinoma)); choriocarcinoma; chordoma; craniopharyngioma; colorectal cancer (e.g., colon cancer, rectal cancer, colorectal adenocarcinoma); connective tissue cancer; epithelial cancer; epithelioma; endothelial sarcoma (e.g., Kaposi sarcoma, multiple idiopathic hemorrhagic sarcoma); endometrial cancer (e.g., corpus cancer, uterine sarcoma); esophageal cancer (e.g., esophageal adenocarcinoma, Barrett adenocarcinoma); Ewing sarcoma; eye cancer (e.g., intraocular melanoma, retinoblastoma); familial eosinophilia; gallbladder cancer; gastric cancer (such as gastric adenocarcinoma); gastrointestinal stromal tumor (GIST); germ cell cancer; head and neck cancer (e.g., head and neck squamous cell carcinoma, oral cancer (e.g., oral squamous cell carcinoma), laryngeal cancer (e.g., laryngeal cancer, pharyngeal cancer, hypopharyngeal cancer, oropharyngeal cancer)); hematopoietic cancer (e.g., leukemia, e.g., acute lymphoblastic leukemia (ALL) (e.g., B-cell ALL, T-cell ALL), acute myeloid leukemia (AML) (e.g., B-cell AML, T-cell AML), chronic myeloid leukemia (CML) (e.g., B-cell CML, T-cell CML), and chronic lymphocytic leukemia (CLL) (e.g., B-cell CLL, T-cell CLL)); Hodgkin lymphoma (HL) (e.g., B-cell HL, T-cell HL) and non-Hodgkin lymphoma (NHL) (e.g., B-cell NHL such as diffuse large B-cell lymphoma (DLCL) (e.g., diffuse large B-cell lymphoma), follicular lymphoma, chronic lymphocytic leukemia / small lymphocytic lymphoma (CLL / SLL), mantle cell lymphoma (MCL), marginal zone B-cell lymphoma (e.g., mucosa-associated lymphoid tissue (MALT) lymphoma, nodal marginal zone B-cell lymphoma, splenic marginal zone B-cell lymphoma), primary mediastinal B-cell lymphoma, Burkitt lymphoma, lymphoplasmacytic lymphoma (e.g.,Waldenström macroglobulinemia, hairy cell leukemia (HCL), immunoblastic large cell lymphoma, precursor B lymphoblastic lymphoma and primary central nervous system (CNS) lymphoma, and T-cell non-Hodgkin lymphomas such as precursor T lymphoblastic lymphoma / leukemia, peripheral T-cell lymphoma (PTCL) (e.g., cutaneous T-cell lymphoma (CTCL) (e.g., mycosis fungoides, Sézary syndrome), angioimmunoblastic T-cell lymphoma, extranodal natural killer T-cell lymphoma, enteropathy-type T-cell lymphoma, subcutaneous panniculitis-like T-cell lymphoma, and anaplastic large cell lymphoma); one or more mixed states of the above leukemia / lymphomas; and multiple myeloma (MM)), heavy chain disorders (e.g., alpha chain disorder, gamma chain disorder, mu chain disorder); hemangioblastoma; hypopharyngeal cancer; inflammatory myofibroblastic tumor; immunocyte amyloidosis; kidney cancer (e.g., nephroblastoma also known as Wilms tumor, renal cell carcinoma); liver cancer (e.g., hepatocellular carcinoma (HCC), malignant hepatocellular carcinoma); lung cancer (e.g., bronchogenic carcinoma, small cell lung cancer (SCLC), non-small cell lung cancer (NSCLC), lung adenocarcinoma); leiomyosarcoma (LMS); mastocytosis (e.g., systemic mastocytosis); muscle cancer; myelodysplastic syndrome (MDS); mesothelioma; myeloproliferative disorder (MPD) (e.g., polycythemia vera (PV), essential thrombocythemia (ET), agnogenic myeloid metaplasia (AMM), myelofibrosis (MF), chronic idiopathic myelofibrosis, chronic myelogenous leukemia (CML), chronic neutrophilic leukemia (CNL), hypereosinophilic syndrome (HES) also known as); neuroblastoma; neurofibromatosis (e.g.Neurofibromatosis (NF) type 1 or type 2, schwannomatosis; neuroendocrine tumors (e.g., gastroenteropancreatic neuroendocrine tumors (GEP-NET), carcinoid tumors); osteosarcoma (e.g., bone cancer); ovarian cancer (e.g., bladder adenocarcinoma, ovarian embryonal carcinoma, ovarian adenocarcinoma); papillary thyroid cancer; pancreatic cancer (e.g., pancreatic adenocarcinoma (pancreatic adenocarcinoma), intraductal papillary mucinous neoplasm (IPMN), pancreatic islet cell cancer); penile cancer (e.g., penile and scrotal Paget's disease); peritoneal cancer (e.g., primary peritoneal cancer or peritoneal carcinomatosis. Secondary peritoneal cancer that metastasizes to the abdominal cavity after occurring in other parts of the body such as the digestive tract, pancreas, melanoma, breast, lung, ovary), pineal tumor; primitive neuroectodermal tumor (PNT); plasmacytoma; paraneoplastic syndrome (paraneoplastic syndrome); intraepithelial neoplasia; prostate cancer (e.g., prostatic adenocarcinoma); rectal cancer; rhabdomyosarcoma; salivary gland cancer; skin cancer (e.g., squamous cell carcinoma (SCC), keratoacanthoma (KA), melanoma, basal cell carcinoma (BCC)); small intestine cancer (e.g., appendiceal cancer); soft tissue sarcoma (e.g., malignant fibrous histiocytoma (MFH), liposarcoma, malignant peripheral nerve sheath tumor (MPNST), chondrosarcoma, fibrosarcoma, myxosarcoma); sebaceous gland cancer; small intestine cancer; sweat gland cancer; synovial tumor; testicular cancer (e.g., seminoma, testicular embryonal tumor), testicular cancer (seminoma, testicular embryonal carcinoma); thyroid cancer (papillary thyroid cancer, papillary thyroid cancer (PTC), medullary thyroid cancer); urethral cancer; vaginal cancer; vulvar cancer (such as vulvar Paget's disease), including but not limited to these.

[0142] In one embodiment, the tumor to be treated is a metastatic tumor. According to the present disclosure, the term "metastatic tumor" refers to a tumor formed from tumor cells that originated from somewhere in the body other than where the metastatic tumor is located. The term "metastatic" refers to the spread or metastasis of cancer cells from the primary or initially formed tumor to other organs or tissues. During the process of metastasis, tumor cells break away from the initially formed (primary) tumor and form new tumors in other organs or tissues of the body through the blood or lymphatic system. The new metastatic tumor is the same type of cancer as the primary tumor. In the organ or tissue where the secondary (metastatic) tumor is present, there is a "secondary tumor" of the histotype of the primary or initially formed tumor, rather than the histotype of the organ or tissue where the tumor is present. For example, prostate cancer that has metastasized to the bone is called metastatic prostate cancer and contains cancerous prostate cancer cells that proliferate within the bone tissue. In certain embodiments, the metastatic tumor may be a diffuse tumor, i.e., a tumor that has spread extensively, rather than a localized or focal tumor.

[0143] In one embodiment, the tumor is a HER2-positive tumor such as a HER2-positive breast, bladder, pancreatic, ovarian, or gastric tumor.

[0144] In a preferred embodiment, the tumor is selected from peritoneal tumors including primary peritoneal tumors and secondary peritoneal tumors, neuroendocrine tumors including gastroenteropancreatic neuroendocrine tumors and pheochromocytomas or paragangliomas (PPGLs), prostate tumors, neuroblastomas, meningiomas, lymphomas, Merkel cell carcinomas, breast tumors, renal cell tumors, and salivary gland carcinomas. In a particular embodiment, the secondary peritoneal cancer tumor is a peritoneal carcinomatosis tumor, i.e., a tumor that has metastasized into the abdominal cavity after occurring elsewhere in the body, such as in the gastrointestinal tract, pancreas, melanoma, breast, lung, ovary, etc.

[0145] In one embodiment, the present disclosure relates to nanoparticles containing high-Z elements for use in a method of treating a tumor by radiopharmaceutical therapy, wherein the tumor is a HER-2 positive tumor, more specifically a HER-2 breast tumor, and in a subject in need thereof, the method comprises the following combination administration: - An effective amount of the nanoparticles containing the high-Z element as described herein, more specifically AGuIX nanoparticles as described herein, and - An effective amount of 177 Lu-anti-HER2 antibody, and more specifically 177 Lu-trastuzumab.

[0146] In one embodiment, the present disclosure relates to nanoparticles comprising a high-Z element for use in a method of treating a tumor by radiopharmaceutical therapy, wherein in a subject in need thereof, the tumor is an SSTR2-positive tumor such as an SSTR2 midgut neuroendocrine tumor, and the method comprises the following combination administration: - An effective amount of the nanoparticles comprising the high-Z element as described herein, more specifically AGuIX nanoparticles as described herein, and - An effective amount of a somatostatin analog targeting the SSTR2 receptor, such as octreotide (DOTATOC) or octreotate (DOTATATE), and more specifically 177 Lu-DOTATATE.

[0147] Route of administration

[0148] In one embodiment, the nanoparticles and / or the therapeutic radiopharmaceutical are administered to the subject using a route selected from local (intratumoral (IT), intraarterial (IA), subcutaneous, intravenous (IV), intradermal, airway (inhalation), intraperitoneal, intramuscular, intrathecal, intraocular or oral routes).

[0149] Short-term intraperitoneal radioimmunotherapy (BIP-RIT) or short-term intraperitoneal TRT

[0150] In one embodiment, the present disclosure relates to nanoparticles comprising a high-Z element for use in a method of treating a tumor by radiopharmaceutical therapy in a subject in need thereof, the method comprising: (i) Tumor resection for tumors that have occurred intraperitoneally or spread intraperitoneally, such as appendiceal tumors, colon tumors, gastric tumors, ovarian tumors, peritoneal mesotheliomas, (ii) co - administration into the peritoneal cavity of nanoparticles containing high - Z elements and therapeutic radiopharmaceuticals containing radionuclides by the method described herein, more specifically the AGuIX nanoparticles described herein, and (iii) Optionally, for example, by washing the peritoneal cavity with physiological saline using a peristaltic pump, removing the therapeutic radiopharmaceutical not bound to the tumor.

[0151] In the present disclosure, the term "cytoreductive surgery" is also referred to as "CRS" and means a surgical procedure aimed at reducing the amount of tumor cells in the peritoneal cavity for patients with tumors (peritoneal carcinomatosis) that have spread intraperitoneally. It is commonly used in the treatment of ovarian cancer but can also be used for other abdominal malignancies.

Examples

[0152] The present disclosure is further illustrated by the following examples.

Examples

[0153] Materials and Methods

[0154] Cell Lines The SK-OV-3-luc cell line derived from human ovarian serous cystadenocarcinoma was selected. The cells were obtained from the American Type Culture Collection (ATCC) and transfected to express the luciferase gene, which enables tracking of intraperitoneal (IP) tumor growth by bioluminescence imaging. The cells were cultured in DMEM / F12 culture medium supplemented with 10% fetal bovine serum and 1% penicillin / streptomycin at 37 °C in a 5% CO2 atmosphere. Hygromycin 0.1 mg / mL was added to the medium to select cells expressing the luciferase gene. SK-OV-3-luc expresses the EGFR family HER2 receptor, which can be targeted with trastuzumab (Herceptin®, Roche). Additionally, the cell line exhibits two major characteristics of HGSOC, namely resistance to platinum and p53 mutations. In additional cancer models of A431 (human vulvar epidermoid carcinoma), B16F10 (mouse melanoma) and MiaPaca2 (human pancreatic cancer, expressing somatostatin sst2) obtained from the American Type Culture Collection (ATCC), in vitro radiosensitization and AGuIX® cytotoxicity have been measured.

[0155] Animals Athymic female Swiss nude mice (6 - 8 weeks old) (Charles River) were housed in the animal facility for 1 week before use. They were housed at 22 °C, 55% humidity, with a 12-hour light / dark cycle and given free access to food and water. Body weight was monitored weekly and the mice were examined throughout the study period. These were intraperitoneally (IP) xenografted with 3 x 10 6 SK-OV-3-luc cells in 200 μl of DMEM-F12 serum-free medium. Tumor growth was monitored by bioluminescence imaging. During the study period, the health status of the mice was observed and no clinical signs of pain or distress were noted. Four weeks after treatment, tumor nodules were harvested and measured. Results are presented as mean tumor volume (mg) for different treatment groups.

[0156] Treatment in vitro Trastuzumab (Herceptin, Roche) conjugated with p-SCN-benzyl-DOTA (macrocyclic compound, plano, Texas, USA) was labeled with Lu( 177 Lu( 177 Lu-trastuzumab) at a specific activity of 200 MBq / mg. AGuIX® was dissolved directly in 1 mL of water for injection (WFI), stirred at 25 °C for 10 minutes, and then diluted with DMEM / F12 culture medium to reach a concentration range of 1 - 10 mg / mL. 177 SK-OV-3 and A431 cells were treated with Lu-trastuzumab. Additionally, for the treatment of MiaPaca2 cells, LUTATHERA( 177 Lu-DOTATATE, targeting sst2) was used, and for the treatment of B16F10 cells, I-TA99 mAb targeting the TYRP1 / gp75 receptor was used. It is noteworthy that LUTATHERA is routinely used clinically for the treatment of patients with midgut neuroendocrine tumors (Strosberg et al., 2017; Strosberg et al., 2021). 125 I-TA99 mAb was used. It is worth noting that LUTATHERA is routinely used clinically for the treatment of patients with midgut neuroendocrine tumors (Strosberg et al., 2017; Strosberg et al., 2021).

[0157] in vivo On day 14 after xenotransplantation, mice were divided into different groups (n = 8) and received the IP injections summarized in Table 1 below:

[0158]

Table 1

[0159] ICP-MS 10 mg (7200 nmol Gd) of AGuIX® was administered to SK-OV-3-luc xenografts, and the target tumors and organs were recovered ex vivo 30 minutes, 6 hours, 24 hours, and 48 hours after injection (n = 3 mice per time point). Samples were analyzed by ICP-MS for gadolinium quantification.

[0160] In vivo distribution of radiolabeled antibodies Nude female Swiss mice without thymus were 3x10 6SK-OV-3-luc cells were intraperitoneally (IP) xenografted. After 14 days, mice were 177 injected intraperitoneally with Lu-labeled trastuzumab. Tumors and organs were harvested, weighed, and radioactivity uptake was measured by γ-counting. For each organ or tumor, the percentage of injected activity per gram of tissue (%IA / g) was plotted.

[0161] Results 10 MBq of radioactivity is not effective enough to evaluate the radiosensitizing effect of AGuIX®. The results shown in Figure 2 indicate that the combination of TRT + AGuIX® is as follows: - The total tumor volume decreased by 97% (*** p = 0.0006) compared to the sodium chloride control. - The total tumor volume decreased by 89% (** p = 0.006) compared to trastuzumab + AGuIX®. - No significant difference was observed when compared to TRT alone.

[0162] 177 The maximum tolerated activity (MTA) of Lu-trastuzumab (10 MBq) showed a strong therapeutic effect and the potential radiosensitization of AGuIX nanoparticles could not be evaluated. In further experiments, 177 the radioactivity of Lu-trastuzumab was decreased to 5 and 2.5 MBq.

[0163] The activity of 5 MBq of 177 Lu-trastuzumab associated with 10 mg of AGuIX® showed a tendency towards radiosensitization

[0164] The results in Figure 3 are: - 2.5 MBq of 177 Lu-trastuzumab + / − AGuIX® did not show significant efficacy compared to the trastuzumab + AGuIX® control. - 5 MBq of 177Lu-trastuzumab + AGuIX® reduced the total tumor volume by 97% (*** p = 0.0003) and 94% (** p = 0.001), respectively, compared to NaCl and the trastuzumab + AGuIX® control. - No significant difference was observed when comparing 5 MBq + AGuIX® to RT alone. 5 MBq of 177 the radioactivity injected with Lu-trastuzumab was established as the baseline radioactivity for further studies. The lack of a significant radiosensitizing effect may be related to the high efficacy of RT alone, as well as the uptake and retention time of NPs in the tumor. The biodistribution of AGuIX® was further performed in animals with cancer to evaluate its uptake / clearance kinetics.

[0165] AGuIX® showed rapid clearance and insufficient long-term tumor retention. The results in Figure 4 show a rapid flashout of the nanoparticles in the tumor between 30 minutes and 6 hours after injection. This clearance kinetics is suitable when AGuIX® and an external radiation beam are combined, where irradiation reaches AGuIX® in a flash mode at a high dose rate. In the RT approach, irradiation is performed at a lower dose rate but maintained over a long period. Therefore, a longer residence time of the nanoparticles in the tumor was desired. Overall, these observations led to the design of three fractionated dosing regimens of AGuIX® in combination with RT. The fractionated regimen of AGuIX® significantly increased tumor regression compared to RT alone.

[0166] The results in Figure 5A show a significant difference between RT (5 MBq) and fractionated regimen 3 (4 x 5 mg). To compare the responses to both treatments, the Response Evaluation Criteria In Solid Tumors (RECIST) criteria (Gengenbacher et al., 2017) were evaluated (Figure 5B). Briefly, the RECIST-based three-category method classifies drug responses into three categories: complete response (CR), stable disease (SD), and progressive disease (PD) based on relative tumor volume or RTV at a late day compared to the start of treatment (OR: RTV≤0.65, PD: RTV≥1.35, SD: 0.65<RTV<1.35). The results are shown in Figure 5B and Table 2 below:

[0167]

Table 2

[0168] In vitro, AGuIX® radiosensitizes cancer cells to β and Auger TRT. The results in Figure 6 show the following: - Figure 6A: Clonogenic cell survival of SK-OV-3 and A431 cells exposed to 177 Lu-trastuzumab at 0.5, 1, 2, and 4 MBq / mL ± 10 mg / mL of AGuIX®. - Figure 6B: Clonogenic cell survival of B16F10 cells exposed to 125 I-TA99 at 4 MBq / mL ± 1 mg / mL of AGuIX®. - Figure 6C: Clonogenic cell survival of MiaPaca2 cells exposed to LUTATHERA® at 0.8, 2, and 4 MBq / mL ± 1, 5, and 10 mg / mL of AGuIX®.

[0169] No significant cytotoxic effect was observed for any of the test cell lines with AGuIX® treatment alone. The gynecological cancer cell lines SK-OV-3 and A431 were 177When incubated in combination with Lu-trastuzumab and AGuIX® 10 mg / mL, a significant radiosensitizing effect was observed (Figure 6A). Consistently, radiation sensitization was observed when B16F10 mouse melanoma cells were exposed to 125 I-TA99 at 4 MBq / mL in the presence of 1 mg / mL of AGuIX® (Figure 6B). Similarly, when MiaPaca2 pancreatic cancer cells were treated with LUTATHERA® in the presence of 10 mg / mL of AGuIX®, a significant radiosensitizing effect was shown (Figure 6C).

[0170] Conclusion In vitro and in vivo results demonstrate radiosensitization and enhanced therapeutic efficacy of therapeutic radiopharmaceuticals while reducing the total injected radioactivity when co-administered with AGuIX®. These results may have a significant impact on patients by reducing radiation-induced toxicity.

[0171] Moreover, the inventors generated biodistribution data to track the fate of radiolabeled antibodies 177 Lu-trastuzumab (Figure 7) and AGuIX® nanoparticles in the tumor. Monitoring of NPs in the tumor was ensured by ICPMS measurements, while monitoring of radiolabeled antibodies was ensured by measuring radioactivity in the tumor. As a result, the following was revealed: - The uptake of radiolabeled antibodies in the tumor increases between 0 and 48 hours and then decreases. - The uptake of nanoparticles (NPs) in the tumor is more rapid. It increases within 30 minutes and then decreases. Therefore, by injecting NPs between T24h, T30h, T72h, and T78h after antibody injection, for a given time, NPs and antibodies are simultaneously present in the tumor, i.e., co-localized.

Example

[0172] : Survival of animals by Regimen 3 The survival of animals by administration of Regimen 3 described in Example 1 was assayed. Materials and Methods In this second experiment, mice were injected with 5 mg of AguiX® in 200 μl of aqueous saline solution twice a day (separated by a 6-hour interval), 24 and 72 hours after TRT. The survival of the mice was monitored by bioluminescence measurement for 130 days after treatment. The estimated survival rates by the Kaplan-Meier method were calculated from the day of xenotransplantation until the day of the target event (i.e., bioluminescence of 4×10 10 photon / s) occurred and compared by the log-rank test.

[0173] Results The results are shown in Figure 8. The established Kaplan Meyer survival curves confirm that Regimen3 (R3) led to the strongest improvement in the median survival (Figure 8). Specifically, 177 Lu-trastuzumab + R3] resulted in a significant prolongation of the survival period (median survival value = 97 days; 2 mice were cured for more than 11 days), compared to NaCl (median survival value = 30 days; **** p<0.0001), trastuzumab + AGuiX® (median survival value = 33 days; **** p<0.0001), and 5 MBq 177 Lu-trastuzumab alone (median survival value = 69 days; *p = 0.016).

Example

[0174] : Co-localization of high-Z-containing NPs and lysosomes according to the present invention Materials and Methods To evaluate the localization of the nanoparticles with respect to mitochondria and lysosomes, SK-OV-3-luc cells were incubated with AGuIX®-AF488 (i.e., AGuIX® functionalized with an Alexa Fluor dye) for 18 hours and then with Mitotracker® Red CM-H2Xros (M7513, Thermofisher), or Lysotracker® Red DND-99 (L7528, Thermofisher) for 45 minutes.

[0175] Result Using the latter method, it was shown that AGuiX (registered trademark) co-localizes with lysosomes but not with mitochondria (data not shown). These results were confirmed by transmission electron microscopy (TEM) imaging.

Example

[0176] : Role of Iron in the Radiosensitizing Effect of High-Z-Containing NPs According to the Present Invention Materials and Methods Cells were seeded in 6-well plates at a density of 100 - 300 cells / well. The next day, 177 177 Lu-trastuzumab was radiolabeled to increase radioactivity (0 - 4 MBq / mL) and incubated with 10 mg / mL of AGuiX (registered trademark) with or without co-incubation for 18 hours in the presence of 100 μM deferiprone (DFP) (Selleck Chemicals). Then, the medium was removed, the cells were washed twice with 1X PBS, fresh medium was added, and the cells were stored for clonogenic survival as described above. Three independent experiments were performed three times.

[0177] Result The results are shown in FIGS. 9 and 10. The results in Figure 9 show that the priming effect of AGuiX® against TRT disappears in the presence of deferiprone (an iron chelator), as measured by the clonogenic survival of treated cells. Lysosomes contain iron involved in the formation of reactive oxygen species (ROS) via the Fenton reaction. This process is exacerbated when AGuiX® NPs are used in combination with TRT, leading to lysosomal disruption. Oxidation treatment induces lysosomal disruption, as indicated by a decrease in the number of lysosomes and a decrease in cytoplasmic pH (data not shown). Iron released from disrupted lysosomes also generates a wave of ROS in the cytoplasm that leads to DNA damage, as indicated by an increase in micronuclei formation (data not shown). The role of ROS in the priming effect of AGuiX® against TRT is confirmed by the use of ROS scavengers (DMSO, NAC) and antioxidant enzymes (catalase). As a result, dramatic lipid peroxidation is observed, suggesting a potential role for ferroptosis in the toxicity mediated by AGuIX®.

[0178] From the above results, it became clear that the effectiveness of the combination of TRT + AGuIX® is mediated by ferroptosis.

[0179] These results were confirmed by TEM images of cells treated with TRT and AGuiX® in the presence or absence of deferiprone (Figure 10). The TEM micrographs shown in Figure 10 depict SKOV3 cells 48 hours after treatment with 1 MBq / mL of 177 Lu-trastuzumab + 10 mg / mL of AGuiX® in the presence of the iron chelator deferiprone (DFP). Cytoplasmic lysis / necrosis-like features are indicated by yellow arrows. The left panel of Figure 10 shows the outcome of TRT + AGuiX® treatment after 48 hours of culture, and the right panel of Figure 10 shows the same treatment in the presence of DFP. Cytoplasmic vacuolization (arrows) disappears in the presence of the iron chelator.

[0180] Overall, the TEM micrographs of Figure 10 show that the combination of TRT+AGuIX® results in dramatic ultrastructural changes as observed, which are characterized by extensive cytoplasmic vacuolization followed by evident cytoplasmic lysis and the accumulation of autophagosomes and damaged undigested cell components. Thus, iron chelation has been shown to increase the survival of TRT+AGuIX®-treated cells, allow for the restoration of lysosomal integrity, and reverse the above-described ultrastructural changes.

[0181] References Aarts F, Hendriks T, Boerman OC, Koppe MJ, Oyen WJG, Bleichrodt RP. A Comparison Between Radioimmunotherapy and Hyperthermic Intraperitoneal Chemotherapy for the Treatment of Peritoneal Carcinomatosis of Colonic Origin in Rats. Ann Surg Oncol.;14(11):3274-82 (2007). Aarts F, Bleichrodt RP, de Man B, Lomme R, Boerman OC, Hendriks T. The Effects of Adjuvant Experimental Radioimmunotherapy and Hyperthermic Intraperitoneal Chemotherapy on Intestinal and Abdominal Healing after Cytoreductive Surgery for Peritoneal Carcinomatosis in the Rat. Ann Surg Oncol.;15(11):3299-307. (2008). Andersson H, Elgqvist J, Horvath G, Hultborn R, Jacobsson L, Jensen H, et al. Astatine-211-labeled antibodies for treatment of disseminated ovarian cancer: an overview of results in an ovarian tumor model. Clin Cancer Res.;9(10 Pt 2):3914S-21S. (2003). Alvarez RD, Huh WK, Khazaeli MB, Meredith RF, Partridge EE, Kilgore LC, et al. A Phase I study of combined modality (90)Yttrium-CC49 intraperitoneal radioimmunotherapy for ovarian cancer. Clin Cancer Res.;8(9):2806-11 (2002). Elgqvist J, Andersson H, Back T, Hultborn R, Jensen H, Karlsson B, et al. Therapeutic efficacy and tumor dose estimations in radioimmunotherapy of intraperitoneally growing OVCAR-3 cells in nude mice with (211)At-labeled monoclonal antibody MX35. J Nucl Med.;46(11):1907-15 (2005). Epenetos AA, Hird V, Lambert H, Mason P, Coulter C. Long term survival of patients with advanced ovarian cancer treated with intraperitoneal radioimmunotherapy. Int J Gynecol Cancer.;10(s1):44-6 (2000). Gengenbacher, N., Singhal, M. & Augustin, H. Preclinical mouse solid tumour models: status quo, challenges and perspectives. Nat Rev Cancer 17, 751-765 (2017). Goodman MD, McPartland S, Detelich D, Saif MW. Chemotherapy for intraperitoneal use: a review of hyperthermic intraperitoneal chemotherapy and early post-operative intraperitoneal chemotherapy. J Gastrointest Oncol.;7(1):45-57 (2016). Hird V, Maraveyas A, Snook D, Dhokia B, Soutter W, Meares C, et al. Adjuvant therapy of ovarian cancer with radioactive monoclonal antibody. Br J Cancer.;68(2):403-6 (1993). Meredith RF, Buchsbaum DJ, Alvarez RD, LoBuglio AF. Brief Overview of Preclinical and Clinical Studies in the Development of Intraperitoneal Radioimmunotherapy for Ovarian Cancer. Clin Cancer Res.;13(18):5643s-5s (2007). Koppe MJ, Bleichrodt RP, Oyen WJG, Boerman OC. Radioimmunotherapy and colorectal cancer. British Journal of Surgery.; 92(3):264-76 (2005) Milenic DE, Garmestani K, Brady ED, Albert PS, Ma D, Abdulla A, et al. Targeting of HER2 Antigen for the Treatment of Disseminated Peritoneal Disease. Clin Cancer Res.;10(23):7834-41 (2004). Muller C, Zhernosekov K, Koster U, Johnston K, Dorrer H, Hohn A, et al. A Unique Matched Quadruplet of Terbium Radioisotopes for PET and SPECT and for α- and β - -Radionuclide Therapy: An In Vivo Proof-of-Concept Study with a New Receptor-Targeted Folate Derivative. J Nucl Med. ;53(12):1951-9. (2012) Sgouros G, Bodei L, McDevitt MR, Nedrow JR. Radiopharmaceutical therapy in cancer: clinical advances and challenges. Nat Rev Drug Discov.;19(9):589-608 (2020) Pouget JP, Navarro-Teulon I, Bardies M, Chouin N, Cartron G, Pelegrin A, et al. Clinical radioimmunotherapy-the role of radiobiology. Nat Rev Clin Oncol.;8(12):720-34 (2011) Pouget JP, Lozza C, Deshayes E, Boudousq V, Navarro-Teulon I. Introduction to Radiobiology of Targeted Radionuclide Therapy. Front Med.; 17;2:12 (2015) Seidl C, Zockler C, Beck R, Quintanilla-Martinez L, Bruchertseifer F, Senekowitsch-Schmidtke R. 177Lu-immunotherapy of experimental peritoneal carcinomatosis shows comparable effectiveness to 213Bi-immunotherapy, but causes toxicity not observed with 213Bi. Eur J Nucl Med Mol Imaging.; 38(2):312-22. (2011) Strosberg J, El-Haddad G, Wolin E, Hendifar A, Yao J, Chasen B, et al. Phase 3 Trial of 177Lu-Dotatate for Midgut Neuroendocrine Tumors. N Engl J Med.;376(2):125-35 (2017) Strosberg J, Leeuwenkamp O, Siddiqui MohdK. Peptide receptor radiotherapy re-treatment in patients with progressive neuroendocrine tumors: A systematic review and meta-analysis. Cancer Treat Rev.; Vol. 93:102141 (2021) Sugarbaker PH. Comprehensive management of peritoneal surface malignancy using cytoreductive surgery and perioperative intraperitoneal chemotherapy: the Washington Cancer Institute approach. Expert Opinion on Pharmacotherapy.Expert Opin Pharmacother;10(12):1965-77 (2009). Verheijen RH, Massuger LF, Benigno BB, Epenetos AA, Lopes A, Soper JT, et al. Phase III Trial of Intraperitoneal Therapy With Yttrium-90-Labeled HMFG1 Murine Monoclonal Antibody in Patients With Epithelial Ovarian Cancer After a Surgically Defined Complete Remission. JCO.;24(4):571-8 (2006).

Claims

1. A high-Z element-containing nanoparticle for use in a method of treating a tumor by a radiopharmaceutical therapy in a subject in need of treatment of the tumor by the radiopharmaceutical therapy, the method comprising co-administering an effective amount of the high-Z element-containing nanoparticle and a therapeutic radiopharmaceutical containing an effective amount of a radionuclide, the high-Z element-containing nanoparticle containing an element having an atomic Z number of 40 or more, preferably 50 or more, and the nanoparticle having an average hydrodynamic diameter of 20 nm or less, for example 1 to 10 nm, preferably 2 to 8 nm.

2. The nanoparticle according to claim 1, wherein the nanoparticle enhances the therapeutic effect of the radiopharmaceutical.

3. The nanoparticle for use according to claim 1 or 2, wherein the high-Z element is selected from heavy metals, more preferably Au, Ag, Pt, Pd, Sn, Ta, Zr, Tb, Tm, Ce, Dy, Er, Eu, La, Nd, Pr, Lu, Yb, Bi, Hf, Ho, Pm, Sm, In, and Gd, and mixtures thereof.

4. wherein the radionuclide is １７７ Lu, １６１ Tb, １８６ Re, １３１ I, ９０ Y, ２２５ Ac / ２１３ Bi, ２２３ Ra, ２１２ Pb / ２１２ Bi, ２２７ Th, ２１１ At, ９７ Ru, １０３ Pd, ６７ Ga, １９５ｍ Pt, １９３ｍ Pt, １２５ I, １１１ nanoparticles for use according to any of claims 1 to 3, selected from In and mixtures thereof.

5. The nanoparticle for use according to any one of claims 1 to 3, wherein the effective amount of the radiopharmaceutical is contained in an amount of 0.5 MBq to 100 GBq.

6. The nanoparticle for use according to any one of claims 1 to 4, wherein the radionuclide is linked to a cancer targeting moiety.

7. The nanoparticle for use according to claim 5, wherein the cancer targeting moiety is an antibody, a peptide or a small molecule ligand.

8. The nanoparticle for use according to any one of claims 6 or 7, wherein the cancer targeting moiety is selected from the following - Anti-HER2 antibodies such as trastuzumab, pertuzumab, or ibritumomab (also called ibritumomab tiuxetan and commercialized under the trademark Zevalin (registered trademark)), anti-EGFR antibodies such as cetuximab or panitumumab, anti-CD20 antibodies such as rituximab or Zevalin, anti-CD33 antibodies such as rituximab, otrexup (TRU-016), mAB 37.1 (BI 836826) or IMGN529 (K7153A-DM1), anti-AMHRII antibodies such as mulrentamab, or anti-TYRP1 / gp75 antibodies such as IMC-20D7S. - Somatostatin analogs such as octreotide (DOTATOC) or octreotate (DOTATATE), or - PSMA small molecule ligands such as 617 ligand, I&T ligand, R2 ligand or MIP-1095 ligand.

9. The therapeutic radiopharmaceutical is １７７ such as Lu-trastuzumab １７７ Lu-anti-HER2 antibody, １７７ such as Lu-DOTATATE １７７ Lu-somatostatin analog, １７７ Lu-PSMA ligand, ９０ Y-rituximab or ９０ such as Y-ibritumomab ９０ Y-anti-CD20 antibody, ２１２ Pb-anti-HER2 antibody, １７７ The nanoparticle for use according to any one of claims 1 to 8, selected from Lu-anti-CD37 antibody.

10. The therapeutic radiopharmaceutical is １３１ I or ２２３ The nanoparticle for use according to any one of claims 1 to 4, which consists of Ra.

11. The nanoparticle for use according to any one of claims 1 to 10, wherein the nanoparticle is administered to a subject in a divided dosing regimen.

12. The nanoparticle for use according to any one of claims 1 to 11, wherein the divided dosing regimen of the nanoparticle comprises 2 to 10 divided doses of the nanoparticle for each administration of the therapeutic radiopharmaceutical administered to the subject.

13. The nanoparticle for use according to any one of claims 1 to 12, wherein the subject is a subject who cannot receive the standard effective dose of radiopharmaceutical therapy.

14. The nanoparticle for use according to any one of claims 1 to 13, wherein the tumor is a radiation-resistant tumor.

15. The nanoparticle for use according to any one of claims 1 to 14, wherein the tumor is selected from peritoneal tumors including primary peritoneal tumors and secondary peritoneal tumors, neuroendocrine tumors including gastroenteropancreatic neuroendocrine tumors and pheochromocytoma or paraganglioma (PPGL), prostate tumors, neuroblastoma, meningioma, lymphoma, Merkel cell carcinoma, breast cancer, renal cell tumors, and salivary gland cancer.

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