Mitochondrially-targeted antioxidant compound for use in radiation therapy

Abstract

The present invention relates to a compound for use as a radiosensitizing agent in radiotherapy, characterized in that the compound is selected from formula (I) or (II): wherein R1, R2, and R3 are the same or different and are independently selected from the group consisting of: substituted or unsubstituted C1-C5 alkyl or H; wherein R4 and R5 are the same or different and independently selected from the group consisting of: H, hydroxyl, carboxyl, amide, unsubstituted or substituted alkyl, unsubstituted or substituted alkenyl and unsubstituted or substituted alkynyl; wherein n is an integer ranging from 2 to 20; or a pharmaceutically acceptable salt thereof.

Description

MITOCHONDRIALLY-TARGETED ANTIOXIDANT COMPOUND FOR USEIN RADIATION THERAPYFIELD OF INVENTION

[0001] The present invention relates to mitochondrially-targeted antioxidant compounds, and their use in combination with radiotherapy.BACKGROUND OF INVENTION

[0002] Tumor hypoxia has for long been known as a factor limiting the sensitivity of cancer cells to photon radiotherapy (e.g. X- and y-rays).

[0003] In particular, solid tumors are metabolically heterogeneous, comprising oxidative and glycolytic cancer and host cells. Oxidative cancer cells are metabolically plastic, as they can use of variety of substrates (glucose, glutamine and other amino acids, lipids, and lactate) to fuel the tricarboxylic acid (TCA) cycle and oxidative phosphorylation (OXPHOS) within mitochondria. This process produces CO2 as a consequence of decarboxylation reactions in the TCA cycle, and consumes O2, the final electron acceptor at the electron transport chain (ETC).

[0004] Oxidative cancer cells are typically located close to perfused blood vessels carrying oxygenated red blood cells (RBCs). Conversely, glycolytic cancer cells primarily populate hypoxic tumor areas, and further comprise proliferating cancer cells that are glycolytic independently of the local pO2 (the Warburg phenotype).

[0005] Compared to oxidative cancer cells, glycolytic cancer cells have less metabolic plasticity because they depend on glucose as an obligatory substrate. Metabolic adaptability refers to the observation that oxidative and glycolytic phenotypes are timely and spatially interchangeable with respect to the composition of the tumor microenvironment (TME). Oxygen, metabolite and metabolic waste concentrationsindeed vary depending on dynamic and structural changes of the tumor vasculature and on consumption and production rates by cancer and host cells. However, when anoxia is reached, cell death and necrosis are inevitable.

[0006] Full radiosensitivity can be achieved at a pCh superior to 10 mm Hg, with cancer cells at lower pCh levels being increasingly radioresistant.

[0007] Among other strategies, intense efforts have been deployed to find appropriate ways to increase cancer cells or tumor tissue oxygenation at the time of therapeutic irradiation. Focuses were set on blood oxygenation (trying to increase the amount of O2 reaching the tumor), radiosensitizers mimicking O2, vasodynamics (trying to selectively dilate tumor blood vessels yet avoiding a shunt effect), RBC velocity, angiogenesis (aiming to normalize the tumor vasculature), hyperthermia and cancer cell metabolism. Among all attempts, only non-invasive hyperthermia, which improves tumor perfusion and inhibits DNA repair, reached clinical use.

[0008] As an alternative (or in addition) to increasing oxygen delivery, inhibiting the oxidative phosphorylation system (OXPHOS) could also result in enhanced tumor oxygenation at the time of irradiation. Several drugs have been tested preclinically for that aim, targeting pathways upstream to OXPHOS (e.g., glycolysis with 2-deoxyglocose and the oxidative pathway of lactate with monocarboxylate transporter inhibitors) or the ETC, directly or indirectly (e.g., Rotenone, Antimycin A, Oligomycin, Metformin, Arsenic trioxide, and Insulin).

[0009] Unfortunately, examples of drugs inhibiting cancer cell respiration that are devoid of any radiosensitizing effects in vivo were also reported. Mito-metforminlO and statins are typical examples of this paradigm.

[0010] Thus, tumor reoxygenation remains a clinical barrier to enhance radiotherapy therapeutic window, as hypoxic tumors are associated with poor prognosis and poor overall survival.

[0011] Hence, there remains a need for novel drugs for improving the effect with radiotherapy. There remains a need for sensitizing cells and tissues to radiation; especially with respect to cancer treatments.

[0012] Hence, there remains a need for alleviating or modulating the negative effects of radiation therapy while maximizing the therapeutic effect. For example, there remains a need for providing radiation therapy with minimal dose unit exposition and maximal therapeutic efficacy.

[0013] There also remains a need for overcoming the drawbacks associated to cell or tissue hypoxia, and more particularly tumor hypoxia.

[0014] The invention has for purpose to meet the above-mentioned needs.SUMMARY

[0015] This invention relates to a compound for use as a radiosensitizing agent in radiotherapy, characterized in that the compound is selected from formula (I) or (II):wherein Ri, R2, and R3 are the same or different and are independently selected from the group consisting of: substituted or unsubstituted C1-C5 alkyl or H; wherein R4 and Rs are the same or different and independently selected from the group consisting of: H, hydroxyl, carboxyl, amide, unsubstituted or substituted alkyl, unsubstituted or substituted alkenyl and unsubstituted or substituted alkynyl; wherein n is an integer ranging from 2 to 20;or a pharmaceutically acceptable salt thereof.

[0016] The invention further relates to a pharmaceutical composition for use as a radiosensitizing agent in radiotherapy; characterized in that the composition comprises or consists of a compound of formula (I) or (II), or a pharmaceutically acceptable salt thereof, or a mixture thereof:wherein Ri, R2, and R3 are the same or different and are independently selected from the group consisting of: substituted or unsubstituted C1-C5 alkyl or H; wherein R4 and Rs are the same or different and independently selected from the group consisting of: H, hydroxyl, carboxyl, amide, unsubstituted or substituted alkyl, unsubstituted or substituted alkenyl and unsubstituted or substituted alkynyl; wherein n is an integer ranging from 2 to 20; or a pharmaceutically acceptable salt thereof.

[0017] The invention further relates to an in vitro method for radiosensitizing a cell, in particular a cancer cell, or composition thereof, comprising steps of: a) providing a cancer cell or preparation thereof; b) bringing into contact the cell or preparation with a compound of formula (I) or (II);wherein Ri, R2, and R3 are the same or different and are independently selected from the group consisting of: substituted or unsubstituted C1-C5 alkyl or H;wherein R4 and R5 are the same or different and independently selected from the group consisting of: H, hydroxyl, carboxyl, amide, unsubstituted or substituted alkyl, unsubstituted or substituted alkenyl and unsubstituted or substituted alkynyl; wherein n is an integer ranging from 2 to 20; or a pharmaceutically acceptable salt thereof. c) administering a unit dose of radiation to the cell or preparation thereof, steps b) and c) being sequential or simultaneous.DEFINITIONS

[0018] In the present invention, the following terms have the following meanings:

[0019] As used herein, the term "pharmaceutical composition" refers to a combination of ingredients that facilitates administration of one or more agents of interest (e.g. a radiosensitizer compound) to a subject. A pharmaceutical composition generally comprises one or more agents of interest in admixture with one or more pharmaceutically acceptable carriers or diluents. Pharmaceutically-acceptable "carriers" and "diluents" are known in the art and generally refer to a pharmaceutically-acceptable materials, compositions, or vehicles, including liquid or solid fillers, diluents, excipients, solvents, binders, or encapsulating materials. Each component in the composition must be "pharmaceutically acceptable" in the sense of being compatible with the other ingredients of a pharmaceutical formulation. Each component the composition, including the radiosenzitizer compound, must also be "biocompatible", such that the composition is suitable for contact with the tissues or organs of a subject without excessive toxicity, irritation, allergic response, immunogenicity, or other problems or complications, commensurate with a reasonable benefit / risk ratio

[0020] As used herein, the expression “pharmaceutically acceptable excipient" refers to an inert vehicle or carrier used as a solvent or diluent in which the pharmaceutically active agent is formulated and / or administered, and which does not produce an adverse, allergic or other reaction when administered to an animal, preferably a human. This includes all solvents, dispersion media, coatings, antibacterial and antifungal agents, isotonic agents, absorption retardants and the like. For human administration,preparations must meet standards of sterility, general safety and purity as required by regulatory agencies, such as the FDA or EMA.

[0021] As used herein, the term “radiation therapy”, or “radiotherapy” refers to the medical use of ionizing radiation, generally as part of cancer treatment to control or kill malignant cells. Ionizing radiation is radiation composed of particles that individually carry enough kinetic energy to liberate an electron from an atom or molecule thereby ionizing it. Ionizing radiation sources may include external radiation sources, for example, x-radiation (x-rays), gamma-radiation (y-rays), beta-radiation (P-rays), neutral or charged particle beams, Auger electron sources, internal radiation sources (brachytherapy or sealed source radiation therapy), and radioisotope sources (systemic radioisotope therapy or unsealed source radiotherapy). The radiosensitizer compounds disclosed herein may be used in combination with any suitable source of ionizing radiation that provides electrons capable of reacting with the compounds. Ionizing radiation may include X-radiation, gamma-radiation, P-radiation, y-radiation, neutral or charged particle radiation, internal radiation (sealed source radiation), Auger electron source, and radioisotope radiation (unsealed source radiotherapy). Other forms of DNA damaging factors are also included in the present invention such as UV-irradiation and / or the directed delivery of radiation from a localized internal radiation source (sealed source) or systemic radioisotopes. A unit dose of radiation is generally measured in gray (Gy).

[0022] The terms "radiosensitizing agent" or “radiosensitizer” may be used interchangeably. They refer to a compound or pharmaceutical composition (e.g. medicament which is capable of increasing the sensitivity of a cell, in particular a tumor cell, to ionizing radiation, thus improving the likelihood of cell destruction upon exposure to such radiation.

[0023] The radiosensitizing agents / compounds / compositions disclosed herein provide a novel combination therapy for disorders treatable by radiation therapy, such as cancer. The combination therapy is thus a chemo-radiotherapy combination that includes a radiosensitizing compound as disclosed herein and ionizing radiation.

[0024] As used herein, the term "combination therapy" means that, at some point during the treatment, the two components of the combination will interact, in particular, at a target site(s). The target site may, for example, be the site of a cancer cell or a tumor. The two or more components of the combination therapy are not necessarily administered together at the same time. The radiosensitizing compound and the ionizing radiation may, for example, be administered simultaneously (e.g. at substantially the same time), sequentially (e.g. staggered times), or at overlapping intervals.

[0025] As used herein, the term "subject" as used herein refers to a human or an animal to be treated, in particular, a mammal. Mammalian animals may include, for example, primate, cow, sheep, goat, horse, dog, cat, rabbit, rat, or mouse. Accordingly, the term may thus encompass or refer to a human, although the compounds disclosed herein are useful in veterinary applications as well. The terms "subject" and "patient" and “individual” may be used interchangeably.

[0026] As used herein, the term "cancer" (e.g. neoplastic disorder) as used herein refers to a disorder involving aberrant cell growth, proliferation or division (e.g. neoplasia). As cancer cells grow and divide they pass on their genetic mutations and proliferative characteristics to progeny cells. A "tumor" (e.g. neoplasm) is an accumulation of cancer cells. The methods and combinations disclosed herein may be used in the treatment or prevention or reduction of likelihood of occurrence, or even likelihood of re-occurrence (i.e. relapse) of cancer, cancer cells, tumors and / or symptoms associated therewith. Unless specified otherwise, all types of cancer are considered, in accordance with the methods, uses and combinations of the present disclosure. They may include, but are not limited to, for example testicular cancer, bladder cancer, cervical cancer, ovarian cancer, breast cancer, prostate cancer, head cancer, neck cancer, lung cancer (e.g. non-small cell lung cancer), endometrial cancer, pancreatic cancer, Kaposi's sarcoma, adrenal cancer, leukemia, stomach cancer, colon cancer, rectal cancer, liver cancer, esophageal cancer, renal cancer, thyroid cancer, uterine cancer, skin cancer, oral cancer, brain cancer, spinal cord cancer, liver cancer, gallbladder cancer, sarcoma, uterine sarcoma osteosarcoma, bone cancer, carcinoma, melanoma, lymphoma, myeloma, or germ cell tumors, a metastatic cancer, a non-metastatic cancer, a solid tumor, a childhood solid tumor, a non-solid tumor, a central nervous system (CNS)-associated cancer, a non-central nervous system (non-CNS) associated cancer, a hematologic cancer, bladder cancer, a brain cancer, breast cancer, colon cancer, gastric cancer, glioma, head cancer, pancreatic cancer, salivary cancer, tongue cancer, thymic epithelial cancer, or metastases thereof.

[0027] As used herein, the terms "treat," "treating" and "treatment" include the eradication, removal, amelioration, modification, reduction, management, or control of a pathological condition, in particular of a tumor, tumor cells or cancer, the minimization, prevention or delay of metastasis, or the prolongation of survival of the subject.

[0028] The radiosensitizing agents considered herein may thus be considered for use in treating, preventing, reducing the likelihood of occurrence, or reducing the likelihood of re-occurrence of a pathological condition.

[0029] As used herein, the term "effective amount" or "therapeutically effective amount" is intended to mean that amount of a therapeutic component, or components (e.g. in a combination therapy), that will elicit a desired biological or medical response in a cell, tissue, tumor, system, or subject, which result is generally sought by a researcher, veterinarian, doctor or other clinician or technician. When referring to the effective amount of a radiosensitizing compound / agent to be administered, in combination with ionizing radiation, the effective amount may be an amount sufficient to provide a desired effect, for example an anti-cancer effect, in the presence of the ionizing radiation. Similarly, when referring to the effective amount of ionizing radiation to be administered in combination with a radiosensitizing compound, the effective amount may be an amount of ionizing radiation sufficient to provide a desired effect, for example an anti-cancer effect in the presence of the compound. Advantageously, the effective amount of one or both components may be lower when the components are combined.

[0030] As used herein, the singular forms "a", "an", and "the" include plural references unless indicated otherwise. Terms of degree such as "substantially", "about" and "approximately", as used herein, mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed. These terms of degree shouldbe construed as including a deviation of at least ±5% of the modified term if this deviation would not negate the meaning of the word it modifies.

[0031] As used herein, the term “comprising” means “consisting at least in part of’. When interpreting each statement in this specification that includes the term "comprising", features other than that or those prefaced by the term may also be present. Related terms such as "comprise" and "comprises" are to be interpreted in the same manner. Accordingly, the term “comprising” may refer more specifically to “consisting of’. Related terms such as "consists of are to be interpreted in the same manner.

[0032] As used herein, the term “MitoQ” may refer indifferently to the commercial name of compound mitoquinol mesylate, corresponding to CAS number 845959-55-9 or a mitoquinol mesylate-containing composition, as sold by company MitoQ and / or Antipodean Pharmaceuticals under commercial reference MitoQ®: and / or a composition comprising a mixture of compounds mitoquinone mesylate and mitoquinol mesylate. Synonyms of “MitoQ” are also reported in the Art, and include Mitoquinol, Mitoubiquinol, Mitoubiquinol mesylate, Mitoquinol methane sulfonate, “Phosphonium, [10-(2,5-dihydroxy-3,4-dimethoxy-6-methylphenyl) decyl] tripehenyl-, methanesulfonate”, MitoQ 10, Mitochondrial -targeted CoQlO, Mitochondrial -targeted ubiquinol.

[0033] As used herein, the term “BRM” or « Biological response modifiers” refers to compounds that are used to treat a disease (e.g. cancer) by changing or adding to naturally occurring processes within the body. Consequently, the terms “biological response modifier therapy”, “biological therapy”, and “biotherapy” refer to a type of treatment that uses substances made from living organisms to treat disease. These substances may occur naturally in the body or may be made in the laboratory. In cancer, some BRM therapies stimulate or suppress the immune system to help the body fight cancer. Other BRM therapies attack specific cancer cells, which may help keep them from growing or kill them. They may also lessen certain side effects caused by some cancer treatments. Types of BRM therapy include immunotherapy (such as cytokines, cancer treatment vaccines, and some antibodies) and some targeted therapies.DETAILED DESCRIPTION

[0034] The inventors report herein the advantageous radiosensitizing properties of a selection of mitochondrially-targeted antioxidant compounds, characterized by a quinone-moiety linked to an antioxidant triphenylphosphonium (TPP+) cation moiety.

[0035] Surprisingly, the inventors provide experimental evidence that a mitochondrially-targeted antioxidant of formula (I) or (II), or mixtures thereof, dose- dependently inhibits cancer cell respiration, with full inhibition reached at nanomolar doses in several different human cancer cell lines. Also surprisingly, it is shown herein that a mitochondrially-targeted antioxidant of formula (I) or (II) can radiosensitize human tumors in mice at a clinically relevant dose.

[0036] Accordingly, a composition comprising such mitochondrially-targeted antioxidants is found efficient for sensitizing cancer cells from a plurality of human cancer cell types, including breast, cervix, colon and prostate cancer cell lines.

[0037] Triphenyl phosphonium quinols and quinones were previously reported in Kelso et al. (“Selective Targeting of a Redox-active Ubiquinone to Mitochondria within Cells”; Journal of Biological Chemistry, Vol. 276, No. 7, 2001), including examples of synthesis of quinone or quinol derivatives, as well as in EP1423396 Bl, US6331532 Bl and US7888335 B2.

[0038] Mitochondrially-targeted antioxidants of formula (I) or (II) were also previously reported as part of food supplements and other mitoquinol mesylate-supplemented food products sold under the name “MitoQ”.

[0039] More recently, Bao et al. (“Mitochondrial-Targeted Antioxidant MitoQ- Mediated Autophagy; A Novel Strategy for Precise Radiation protection”; Antioxidants 2023, 12, 453) reported a MitoQ-antioxidant preparation that could successfully protect normal cells from radiation-induced damage.

[0040] To the knowledge of the inventors, such triphenyl phosphonium quinols and quinones were, however, never reported as radiosensitizing agents in hypoxic tissues; let alone cancer cells. This was unexpected, because the reported mode of action of such compounds is classically that of an antioxidant inactivating mitochondrial reactive oxygen species (mtROS).

[0041] The inventor’s data suggest another mode of action, through which compounds of formulae (I) or (II), salts and mixtures thereof, inserted into the inner mitochondrial membrane could block the electron flux through the electron transport chain (ETC), resulting in O2 sparing.

[0042] Without wishing to be bound by the theory, it is thus proposed that such radiosensitization could occur at least partially through the oxygen enhancement effect (OEE). The OEE reflects the involvement of O2 in the production and propagation of reactive oxygen species (ROS) following water radiolysis, and its ability to stabilize radicals on DNA to produce DNA peroxides.

[0043] Also, without wishing to be bound by the theory, it is proposed herein a mechanism of action similar to coenzyme QlO / ubiquinone with which it shares a similar quinone moiety. Consequently, such compounds of formula (I) or (II) could accept electrons from Complexes I and II. However, due to steric hindrance (TPP+ group), those compounds would not be able then to transfer these electrons to Complex III, and would thus block the electron flux through the ETC.

[0044] This invention thus relates to a compound for use as a radiosensitizing agent, in particular in radiotherapy, characterized in that the compound is selected from formula (I) or (II):wherein Ri, R2, and R3 are the same or different and are independently selected from the group consisting of: substituted or unsubstituted C1-C5 alkyl or H; wherein R4 and Rs are the same or different and independently selected from the group consisting of: H, hydroxyl, carboxyl, amide, unsubstituted or substituted alkyl, unsubstituted or substituted alkenyl and unsubstituted or substituted alkynyl; wherein n is an integer ranging from 2 to 20, for example n being 2, 3, 4, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20; or a pharmaceutically acceptable salt thereof.

[0045] This invention thus also relates to a compound for use as a radiosensitizing agent, in particular in radiotherapy, characterized in that the compound is selected from formula (I) or (II):wherein Ri, R2, and R3 are the same or different and are independently selected from the group consisting of: substituted or unsubstituted C1-C5 alkyl or H; wherein R4 and Rs are the same or different and independently selected from the group consisting of: H, amide, unsubstituted or substituted alkyl, unsubstituted or substituted alkenyl and unsubstituted or substituted alkynyl; wherein n is an integer ranging from 2 to 20; or a pharmaceutically acceptable salt thereof.

[0046] This invention thus also relates to a compound for use as a radiosensitizing agent, in particular in radiotherapy, characterized in that the compound is selected from formula (I) or (II):wherein Ri, R2, and R3 are the same or different and are independently selected from the group consisting of: substituted or unsubstituted C1-C5 alkyl or H; wherein R4 and Rs are the same or different and independently selected from the group consisting of: H, unsubstituted or substituted alkyl, unsubstituted or substituted alkenyl and unsubstituted or substituted alkynyl; wherein n is an integer ranging from 2 to 20; or a pharmaceutically acceptable salt thereof.

[0047] The invention further relates to a compound for use as a radiosensitizing agent, in particular in radiotherapy, characterized in that the compound is selected from particular formula (la) or (lb) or (Ic) or (Id) or (le) or (If), as defined hereafter; with n, Ri, R2, R.3, R4 and Rs, when applicable, being as defined previously.

[0048] In particular, the invention relates to a compound for use as a radiosensitizing agent, in particular in radiotherapy, characterized in that the compound is selected from formula (la) or (lb) or (Ic) or (Id) or (le) or (If):wherein Ri, R2, and R3 are the same or different and are independently selected from the group consisting of: substituted or unsubstituted C1-C5 alkyl or H; wherein R4 and Rs are the same or different and independently selected from the group consisting of: H, hydroxyl, carboxyl, amide, unsubstituted or substituted alkyl, unsubstituted or substituted alkenyl and unsubstituted or substituted alkynyl, wherein n is an integer ranging from 2 to 20, for example n being 2, 3, 4, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20; or a pharmaceutically acceptable salt thereof.

[0049] The present invention further relates to a pharmaceutical composition for use as a radiosensitizing agent, in particular in radiotherapy; characterized in that it comprises or consists of a compound of formula (I) or (II), as defined above, or a pharmaceutically acceptable salt or a mixture thereof.

[0050] Hence, the present invention also relates to a pharmaceutical composition for use as a radiosensitizing agent, in particular in radiotherapy; characterized in that the composition comprises or consists of a compound of formula (I) or (II), as defined above:wherein Ri, R2, and R3 are the same or different and are independently selected from substituted or unsubstituted C1-C5 alkyl or H;wherein R4 and Rs are the same or different and independently selected from the group consisting of: H, hydroxyl, carboxyl, amide, unsubstituted or substituted alkyl, unsubstituted or substituted alkenyl and unsubstituted or substituted alkynyl; wherein n is an integer ranging from 2 to 20; or a pharmaceutically acceptable salt or mixture thereof.

[0051] As used herein, the expression “C1-C5 alkyl” may consist of one selected from a Ci, C2, C3, C4, or Cs alkyl. As used herein, the expression “C1-C5 alkenyl” may consist of one selected from a Ci, C2, C3, C4, or Cs alkenyl. As used herein, the expression “Ci- C5 alkynyl” may consist of one selected from a Ci, C2, C3, C4, or Cs alkynyl.

[0052] As used herein, the expression “substituted”, as in “substituted alkyl” or “substituted alkyl” or “substituted alkynyl”, may refer to those carbon(s) or carbon chain(s) containing substituent such as hydroxyl, carboxylic acid or amide groups, and / or which include one or more side chains or branches. Hence; the term “substituted” used herein means any of the above groups (i.e., alkyl, alkylene, alkoxy, alkylamino, thioalkyl, aryl, aralkyl, cycloalkyl, cycloalkylalkyl, haloalkyl, heterocyclyl, N-heterocyclyl, heterocyclylalkyl, heteroaryl, N-heteroaryl and / or heteroarylalkyl) wherein at least one hydrogen atom is replaced by a bond to a non-hydrogen atoms such as, but not limited to: a halogen atom such as F, Cl, Br, and I; an oxygen atom in groups such as hydroxyl groups, alkoxy groups, and ester groups; a sulfur atom in groups such as thiol groups, thioalkyl groups, sulfone groups, sulfonyl groups, and sulfoxide groups; a nitrogen atom in groups such as amines, amides, alkylamines, dialkylamines, arylamines, alkylarylamines, diarylamines, N-oxides, imides, and enamines; a silicon atom in groups such as trialkylsilyl groups, dialkylaryl silyl groups, alkyl di aryl silyl groups, and triarylsilyl groups; and other heteroatoms in various other groups. “Substituted” also means any of the above groups in which one or more hydrogen atoms are replaced by a higher-order bond (e.g., a double- or triple-bond) to a heteroatom such as oxygen in oxo, carbonyl, carboxyl, and ester groups; and nitrogen in groups such as imines, oximes, hydrazones, and nitriles. For example, “substituted” includes any of the above groups in which one or more hydrogen atoms are replaced with — NRGRH, — NRGC(=O)RH, — NRGC(=O)NRGRH, — NRGC(=O)ORH, — NRGC(=NRg)NRGRH, — NRGSO2RH,— OC(=O)NRGRH, — ORG, — SRG, — SORG, — SO2RG, — OSO2RG, — SO2ORG, =NSO2RG, and — SO2NRGRH. “Substituted also means any of the above groups in which one or more hydrogen atoms are replaced with — C(=O)RG, — C(=O)ORG, — C(=O)NRGRH, — CH2SO2RG, — CH2SO2NRGRH. In the foregoing, RG and RH are the same or different and independently selected from a group comprising or consisting of: hydrogen, alkyl, alkoxy, alkylamino, thioalkyl, aryl, aralkyl, cycloalkyl, cycloalkylalkyl, haloalkyl, heterocyclyl, N-heterocyclyl, heterocyclylalkyl, heteroaryl, N-heteroaryl and / or heteroarylalkyl. “Substituted” further means any of the above groups in which one or more hydrogen atoms are replaced by a bond to an amino, cyano, hydroxyl, imino, nitro, oxo, thioxo, halo, alkyl, alkoxy, alkylamino, thioalkyl, aryl, aralkyl, cycloalkyl, cycloalkylalkyl, haloalkyl, heterocyclyl, N-heterocyclyl, heterocyclylalkyl, heteroaryl, N-heteroaryl and / or heteroarylalkyl group.

[0053] According to some embodiments, the compound of formula (I) or (II) or (la) or (lb) or (Ic) or (Id) or (le) or (If) may be characterized in that R4 and Rs are the same or different and independently selected from the group consisting of: H, hydroxyl, carboxyl, amide, unsubstituted or substituted C1-C5 alkyl, unsubstituted or substituted C1-C5 alkenyl and unsubstituted or substituted Ci-Cs alkynyl.

[0054] According to some embodiments, the compound of formula (I) or (II) or (la) or (lb) or (Ic) or (Id) or (le) or (If) may be characterized in that R4 and Rs are the same or different and independently selected from the group consisting of: H, amide, unsubstituted or substituted C1-C5 alkyl, unsubstituted or substituted C1-C5 alkenyl and unsubstituted or substituted Ci-Cs alkynyl.

[0055] According to some embodiments, the compound of formula (I) or (II) or (la) or (lb) or (Ic) or (Id) or (le) or (If) may be characterized in that R4 and Rs are the same or different and independently selected from the group consisting of: H, unsubstituted or substituted C1-C5 alkyl, unsubstituted or substituted C1-C5 alkenyl and unsubstituted or substituted Ci-Cs alkynyl.

[0056] According to some embodiments, the compound of formula (I) or (II) or (la) or (lb) or (Ic) or (Id) or (le) or (If) may be characterized in that R4 and Rs are the same ordifferent and independently selected from the group consisting of: H, hydroxyl, carboxyl, amide, unsubstituted C1-C5 alkyl, unsubstituted C1-C5 alkenyl and unsubstituted C1-C5 alkynyl.

[0057] According to some embodiments, the compound of formula (I) or (II) or (la) or (lb) or (Ic) or (Id) or (le) or (If) may be characterized in that R4 and Rs are the same or different and independently selected from the group consisting of: H, unsubstituted Ci- C5 alkyl, unsubstituted C1-C5 alkenyl and unsubstituted C1-C5 alkynyl.

[0058] According to particular non-exclusive embodiments, the compound of formula (I) or (II) or (la) or (lb) or (Ic) or (Id) or (le) or (If) may be characterized in that n is an integer ranging from 2 to 20; for example n equals 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20.

[0059] According to particular embodiments, the compound of formula (Ic), (Id), (le) or (If) is characterized in that n is an integer equal to 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20; for example ranging from 4 to 16, in particular ranging from 8 to 12; preferably of 10.

[0060] According to particular embodiments, the compound of formula (I) or (II) or (le) or (If) is characterized in that:- Ri is H, and- R2 and R3 are selected from a C1-C5 alkyl or H.

[0061] According to particular embodiments, the compound of formula (I) or (II) or (le) or (If) is characterized in that:- R2 is CH3, and- Ri and R3 are selected from a C1-C5 alkyl or H .

[0062] According to particular embodiments, the compound of formula (I) or (II) or (le) or (If) is characterized in that:- R3 is CH3, and- Ri and R2 are selected from a C1-C5 alkyl or H .

[0063] According to particular embodiments, the compound of formula (I) or (II) or (le) or (If) is characterized in that:- Ri is H,- R2 is a C1-C5 alkyl or H,- Ra is H or CHs.

[0064] According to particular embodiments, the compound of formula (I) or (II) or (le) or (If) is characterized in that:- Ri is H,- R2 is H or CH3,- R3 is a C1-C5 alkyl or H.

[0065] According to particular embodiments, the compound of formula (I) or (II) or (le) or (If) is characterized in that:- Ri is H,- R2 is H or CH3,- R3 is H or CH3.

[0066] According to preferred embodiments, the compound of formula (I) or (II) or (le) or (If) is characterized in that:- Ri is H,- R2is CH3,- R3 is CH3.

[0067] In some embodiments, the compound as described herein is of formula (I) or (la) or (Ic) or (le), or a pharmaceutically acceptable salt thereof.

[0068] In some embodiments, the compound as described herein is of formula (II) or (lb) or (Id) or (If), or a pharmaceutically acceptable salt thereof.

[0069] Advantageously, the compound may be of formula (III) or (IV), wherein:

[0070] A pharmaceutically acceptable salt may be a non-reactive anion selected from the group consisting of alkyl or aryl sulfonates or nitrates.

[0071] According to some embodiments, a pharmaceutically acceptable salt may be selected from a list consisting of: besylate, mesylate, tritiate, sulfonate, phosphate, acetate, tartrate, malate, citrate, phosphate, maleate, tosylate, hydrochloride.

[0072] In some preferred embodiments, the compound is a pharmaceutically acceptable salt of formula (I) or (II); the pharmaceutically acceptable salt being mesylate.

[0073] According to some preferred embodiments, the pharmaceutical composition for use according to the invention comprises or consists of a mesylate salt of formula (la) or a mesylate salt of formula (II).

[0074] According to some preferred embodiments, the pharmaceutical composition for use according to the invention comprises or consists of a mixture of compounds of formula (I) and formula (II), or pharmaceutically acceptable salts thereof.

[0075] According to some preferred embodiments, the pharmaceutical composition for use according to the invention comprises or consists of a mixture of pharmaceuticallyacceptable salts of compounds of formula (I) and formula (II), at least one of those being a mesylate salt.

[0076] According to some preferred embodiments, the pharmaceutical composition for use according to the invention comprises or consists of a mixture of mesylate salts of compounds of formula (I) and formula (II).

[0077] According to some embodiments, the pharmaceutical composition for use comprises (i) a compound of formula (I) or a pharmaceutically acceptable salt thereof, and (ii) a compound of formula (II) or a pharmaceutically acceptable salt thereof; wherein the compound of formula (II) is in molar excess when compared to the compound of formula (I).

[0078] According to some embodiments, the pharmaceutical composition for use comprises (i) a compound of formula (I) or a pharmaceutically acceptable salt thereof, and (ii) a compound of formula (II) or a pharmaceutically acceptable salt thereof; wherein the compound of formula (I) is in molar excess when compared to the compound of formula (II).

[0079] According to some embodiments, the pharmaceutical composition for use comprises (i) a compound of formula (I) or a pharmaceutically acceptable salt thereof, and (ii) a compound of formula (II) or a pharmaceutically acceptable salt thereof; wherein the molar ratio of [compound of formula (I)] / [compound of formula (II)] ranges from 1:1 to 50:1, for example 1:1 , 2:1 , 3:1 , 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, 20:1, 25:1, 50:1.

[0080] According to some embodiments, the pharmaceutical composition for use comprises (i) a compound of formula (I) or a pharmaceutically acceptable salt thereof, and (ii) a compound of formula (II) or a pharmaceutically acceptable salt thereof; wherein the molar ratio of [compound of formula (II)] / [compound of formula (I)] ranges from 1:1 to 50:1, for example 1:1 , 2:1 , 3:1 , 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, 20:1, 25:1, 50:1.

[0081] In some embodiments, the pharmaceutical composition for use comprises or consists of a mixture of mitoquinol (10-(69-ubiquinolyl)decyltriphenylphosphonium, CAS Number: 845959-55-9) and mitoquinone (10-(69- ubiquinonyl)decyltriphenylphosphonium, CAS Number 444890-41-9), or pharmaceutically acceptable salts thereof.

[0082] In some embodiments, the pharmaceutical composition for use comprises or consists of a mixture of a mesylate salt of mitoquinol (10-(69- ubiquinolyl)decyltriphenylphosphonium, CAS Number: 845959-55-9) and a mesylate salt of mitoquinone (10-(69-ubiquinonyl)decyltriphenylphosphonium, CAS Number : 444890-41-9 ).

[0083] In some embodiments the compound or pharmaceutical composition thereof is for use in a method of sensitizing a patient’s tumor cells to radiation

[0084] In some embodiments the compound or pharmaceutical composition for use, is for use in a method for treating and / or preventing and / or reducing the likelihood of occurrence or re-occurrence of a cancer.

[0085] In some embodiments, the compound as described herein reduces the side effects of radiation therapy, in a patient undergoing radiation therapy.

[0086] The present invention also relates to a compound or pharmaceutical composition as described herein for use in preventing side effects of radiation therapy, in a patient undergoing radiation therapy.

[0087] In some embodiments, the tumor or cancer is selected from the group consisting of : a solid tumor, a childhood solid tumor, a non-solid tumor, a central nervous system (CNS)-associated cancer, a non-central nervous system (non-CNS) associated cancer, a hematologic cancer, bladder cancer, a brain cancer, breast cancer, colon cancer, gastric cancer, glioma, head cancer, leukemia, liver cancer, lung cancer, lymphoma, myeloma, neck cancer, tongue cancer, ovarian cancer, uterine sarcoma, melanoma, testicular cancer, pancreatic cancer, renal cancer, salivary cancer, skin cancer, osteosarcoma, bone cancer stomach cancer, thymic epithelial cancer, and thyroid cancer. In someembodiments, the cancer is not a glioma. In some embodiments, the cancer is a noncentral nervous system (non-CNS) associated cancer.

[0088] In some embodiments, the compound of formula (I) or (II), salt or mixture thereof, or the pharmaceutical composition thereof, is characterized in that it is for administration prior to, or during, exposition to a unit dose of radiation. In some embodiments, the compound for use or the pharmaceutical composition for use is characterized in that it is for administration prior to exposition to a unit dose of radiation.

[0089] When the compound or pharmaceutical composition, as defined above, is administered prior to exposition to a unit dose of radiation, it is advantageously administered in a timeline sufficient for the said compound or composition to reach the cell or tissue that is exposed to radiation. For example, it may be administered at least a few minutes prior to exposition to a unit dose of radiation.

[0090] Advantageously, an administration may comprise or consist of a step of administering the compound of formula (I) or (I), salt or mixture thereof, or a pharmaceutical composition thereof, prior to exposition to a unit dose of radiation, in a timeline selected from the group consisting of: 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 45 min, Ih, Ih 15 min, Ih 30 min, Ih 45 min, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, lOh, l lh, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, 21h, 22h, 23h, 24h, 25h, 26h, 27h, 28h, 29h, 30h, 3 Ih, 32h, 33h, 34h, 35h, 36h, 1 day, 2 days, 3 days, 4 days, 5 days, prior to exposition to a unit dose of radiation.

[0091] An administration prior to exposition to a unit dose of radiation may comprise or consist of administering the compound or the pharmaceutical composition from about 5 min to about 5 days, from about 10 min to about 2 days, from about 15 min to about 1 day, from about 5 min to about 12h, from about 10 min to about lOh, from about 15 min to about 8h, from about 20 min to about 6h, from about 30 min to about 4h, from about 45min to about 3h, from about Ih to about 2h, prior to exposition to a unit dose of radiation.

[0092] An administration prior to exposition to a unit dose of radiation may comprise or consist of administering the compound or the pharmaceutical composition from about 3h to about 3 days, from about 6h to about 2 days, from about 12h to about 36h, from about 18h to about 30h from about 20h to about 28h, prior to exposition to a unit dose of radiation.

[0093] Hence, in some embodiments, the patient is exposed to a unit of radiation at least 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 45 min, Ih, Ih 15 min, Ih 30 min, Ih 45 min, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, lOh, 1 Ih, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, 21h, 22h, 23h, 24h, 25h, 26h, 27h, 28h, 29h, 30h, 3 Ih, 32h, 33h, 34h, 35h, 36h, 1 day, 2 days, 3 days, 4 days, 5 days after the patient is administered the compound or the pharmaceutical composition for use of the invention.

[0094] Hence, in some embodiments, the patient is exposed to a unit of radiation from about 5 min to about 5 days, from about 10 min to about 2 days, from about 15 min to about 1 day, from about 5 min to about 12h, from about 10 min to about lOh, from about 15 min to about 8h, from about 20 min to about 6h, from about 30 min to about 4h, from about 45min to about 3h, from about Ih to about 2h, after the patient is administered the compound or the pharmaceutical composition for use of the invention.

[0095] In some embodiments, the compound for use or the composition for use is for intravenous administration, subcutaneous administration, in situ administration, intraperitoneal administration or oral administration.

[0096] In some embodiments, the compound for use or the composition for use is for topical administration.

[0097] In some embodiments, the pharmaceutical composition for use further comprises an anti-cancer agent.

[0098] According to particular embodiments, the anti-cancer agent may be selected from the list consisting of: an alkylating agent, a platinum preparation, a metabolism antagonist, a topoisomerase inhibitor, a microtubular inhibitor, an anti-cancerous antibiotic, a molecular target drug, a hormone preparation, an immunomodulation drug,an interferon, an interleukin, a plant-derived anticancer agent, a biological response modifier (BRM).

[0099] According to particular embodiments, the pharmaceutical composition for use may comprise or consist of a BRM preparation; in particular including immunotherapy agents, for example one or more selected from the group consisting of: cytokines, cancer treatment vaccines, and antibodies.

[0100] In some embodiments, the compound for use is for administration at least once a day.

[0101] In some embodiments, the compound for use is for administration at a minimal patient daily dose of: 5 mg, 10 mg, 15 mg, 20 mg, 25 mg, 30 mg, 35 mg 40 mg, 45 mg, 50 mg, 55 mg, 60 mg, 65 mg, 70 mg, 75 mg, 80 mg, 85 mg, 90 mg, 95 mg, or 100 mg, 105 mg, 110 mg, 115 mg, 120 mg, 125 mg, 130 mg, 135 mg, 140 mg, 145 mg, 150 mg, 155 mg, 160 mg, 165 mg, 170 mg, 175 mg, 180 mg, 185 mg, 190 mg, 195 mg.

[0102] In some embodiments, the compound for use is for administration at a minimal patient daily dose equal or superior to 10 mg. In some embodiments, the compound for use is for administration at a minimal patient daily dose equal or superior to 100 mg.

[0103] In some embodiments, the compound for use is for administration at a minimal patient daily dose of 80 mg.

[0104] In some embodiments, the compound for use is for administration at a patient daily dose ranges from about 5 mg to about 200 mg, ranges from about 10 to about 180 mg, ranges from about 20 mg to about 150 mg , ranges from about 30 mg to about 130 mg, ranges from about 40 mg to about 120 mg, ranges from about 50 mg to about 110 mg, ranges from about 60 mg to about 100 mg, ranges from about 70 mg to about 90 mg.

[0105] In some embodiments, the compound for use is for administration twice a day at a minimal patient dose of: 5 mg, 10 mg, 15 mg, 20 mg, 25 mg, 30 mg, 35 mg, 40 mg, 45 mg, 50 mg, 55 mg, 60 mg, 65mg, 70 mg, 75 mg, 80 mg, 85 mg, 90 mg, 95 mg, or 100 mg.

[0106] In some embodiments, the compound for use is for administration twice a day at a minimal patient dose of 40 mg for the duration of a radiotherapy treatment.

[0107] In some embodiments, the compound for use is for administration twice a day at a minimal patient dose ranging from about 10 mg to about 100 mg, ranging from about 15 mg to about 90 mg, ranging from about 20mg to about 80 mg, ranging from about 25 mg to about 65 mg, ranging from about 30 mg to about 50 mg, or ranging from about 35mg to about 45mg, for the duration of a radiotherapy treatment.

[0108] The present invention also relates to the use of a compound as defined above, or a pharmaceutically acceptable salt thereof, or a mixture thereof, in the manufacture of a medicament for sensitizing a patient’s tumor cells to radiation.

[0109] The present invention also relates to the use of a compound in the manufacture of a medicament for sensitizing a patient’ s tumor cells to radiation, wherein the compound is selected from formula (I) or (II), or (la), or (lb), or (Ic), or (Id), or (le) or (If) or a pharmaceutically acceptable salt thereof, or a mixture thereof:wherein Ri, R2, and R3 are the same or different and are independently selected from the group consisting of: substituted or unsubstituted C1-C5 alkyl or H; wherein R4 and Rs are the same or different and independently selected from the group consisting of: H, hydroxyl, carboxyl, amide, unsubstituted or substituted alkyl, unsubstituted or substituted alkenyl and unsubstituted or substituted alkynyl, wherein n is an integer ranging from 2 to 20; or a pharmaceutically acceptable salt thereof.

[0110] The present invention also relates to the use of a pharmaceutical composition in the manufacture of a medicament for sensitizing a patient’s tumor cells to radiation, comprising a compound selected from formula (I) or (II), or (la), or (lb), or (Ic), or (Id), or (le) or (If), as defined above, or a pharmaceutically acceptable salt thereof, or a mixture thereof,; and a pharmaceutically acceptable excipient.

[0111] The present invention also relates to the use of a compound in the manufacture of a medicament for sensitizing a patient’ s tumor cells to radiation, wherein the compound is as defined above, or a pharmaceutically acceptable salt thereof or a mixture thereof, wherein the method comprises: a) administering the compound or salt or mixture thereof to a patient; and b) exposing said patient to a unit dose of radiation.

[0112] Hence, the present invention also relates to the use of a compound in the manufacture of a medicament for sensitizing a patient’s tumor cells to radiation, whereinthe compound is selected from formula (I) or (II), or (la), or (lb), or (Ic), or (Id), or (le) or (If), as defined above, or a pharmaceutically acceptable salt thereof or a mixture thereof, wherein the method comprises: a) administering the compound or salt or mixture thereof to a patient; and b) exposing said patient to a unit dose of radiation.

[0113] According to a particular embodiment, the present invention also relates to a pharmaceutical composition for use in a method of sensitizing a patient’s tumor cells to radiation, comprising a compound of formula (III) or (IV):or a pharmaceutically acceptable salt thereof, or a mixture thereof; and a pharmaceutically acceptable excipient; wherein the method comprises: a) administering the pharmaceutical composition to the patient, b) exposing said patient to a unit dose of radiation.

[0114] Hence, the present invention also relates to a method of sensitizing a patient’s tumor cells to radiation, comprising the administration of a compound as defined above, or a pharmaceutically acceptable salt thereof, or a mixture thereof.

[0115] Hence, according to a particular embodiment, the present invention also relates to a method of sensitizing a patient’s tumor cells to radiation, comprising theadministration of a compound characterized in that the compound is selected from formula (I) or (II), or (la), or (lb), or (Ic), or (Id), or (le) or (If) or (III) or (IV), as defined above, or a pharmaceutically acceptable salt thereof, or a mixture thereof.

[0116] The present invention also relates to a method of sensitizing a patient’s tumor cells to radiation, comprising the administration of a pharmaceutical composition, wherein said composition comprises a compound as defined above, or a pharmaceutically acceptable salt thereof, or a mixture thereof ; and a pharmaceutically acceptable excipient

[0117] Hence, the present invention also relates to a method of sensitizing a patient’s tumor cells to radiation, comprising the administration of a pharmaceutical composition, wherein said composition comprises a compound selected from formula (I), (II), (la), or (lb), or (Ic), or (Id), or (le) or (If), or (III), or (IV), as defined above, or a pharmaceutically acceptable salt thereof, or a mixture thereof ; and a pharmaceutically acceptable excipient.

[0118] The present invention also relates to an in vitro method for sensitizing a cell, in particular a cancer cell, or preparation thereof, comprising step of: a) providing a cell or preparation thereof, b) bringing into contact the cell or preparation thereof with a compound as defined above or a pharmaceutically acceptable salt thereof, or a mixture thereof; c) administering a unit dose of radiation to the cell or preparation thereof, steps b) and c) being sequential or simultaneous.

[0119] Hence, the present invention also relates to an in vitro method for sensitizing a cell, in particular a cancer cell, or preparation thereof, comprising step of: a) providing a cell or preparation thereof, b) bringing into contact the cell or preparation thereof with a compound of formula (I), (II), (la), or (lb), or (Ic), or (Id), or (le) or (If), or (III), or (IV), as defined above or a pharmaceutically acceptable salt thereof, or a mixture thereof; c) administering a unit dose of radiation to the cell or preparation thereof, steps b) and c) being sequential or simultaneous.

[0120] Hence, the present invention also relates to an in vitro method for radiosensitizing a cancer cell or composition thereof, comprising steps of:a) providing a cancer cell or preparation thereof; b) bringing into contact the cell or preparation thereof with a compound of formula (I), (II), (la), or (lb), or (Ic), or (Id), or (le) or (If), or (III), or (IV), as defined above or a pharmaceutically acceptable salt thereof, or a mixture thereof ; c) administering a unit dose of radiation to the cell or preparation thereof, steps b) and c) being sequential or simultaneous.

[0121] In some embodiments, the cell is a tumor cell, tissue, and / or cell obtained from a patient with cancer. In particular, the cancer may be selected from the group consisting of : testicular cancer, bladder cancer, cervical cancer, ovarian cancer, breast cancer, prostate cancer, head cancer, neck cancer, lung cancer (e.g. non-small cell lung cancer), endometrial cancer, pancreatic cancer, Kaposi's sarcoma, adrenal cancer, leukemia, stomach cancer, colon cancer, rectal cancer, liver cancer, esophageal cancer, renal cancer, thyroid cancer, uterine cancer, skin cancer, oral cancer, brain cancer, spinal cord cancer, liver cancer, gallbladder cancer, sarcoma, uterine sarcoma osteosarcoma, bone cancer, carcinoma, melanoma, lymphoma, myeloma, or germ cell tumors, a metastatic cancer, a non-metastatic cancer, a solid tumor, a childhood solid tumora non-solid tumor, a central nervous system (CNS)-associated cancer, a non-central nervous system (non-CNS) associated cancer, a hematologic cancer, bladder cancer, a brain cancer, breast cancer, colon cancer, gastric cancer, glioma, head cancer, pancreatic cancer, salivary cancer, tongue cancer, thymic epithelial cancer, or metastases thereof.BRIEF DESCRIPTION OF THE DRAWINGS

[0122] Figure 1. MitoQ dose-dependently reduces the oxygen consumption rate of human breast cancer cells. Fig. 1A and Fig. IB show the oxygen consumption rate (OCR) of 10,000 MCF7 cells (human breast cancer cells) treated with increasing doses of MitoQ for 24 h. The oxygen consumption was measured using Seahorse oximetry. Fig. 1A shows the total OCR measurements over time with the sequential addition of oligomycin, FCCP, and rotenone (Rot) together with antimycin A (AA). Fig. IB shows the basal mitochondrial OCRs (mtOCRs) calculated from the Seahorse traces (n = 4). FullmtOCR inhibition is reached at 500 nM of MitoQ (arrow). Fig. 1C and Fig. ID Same as in Fig. IB, with basal mtOCR in the y-axis, but assessing 5,000 MDA-MB-231 cells (also human breast cancer cells). Fig. ID Full mtOCR inhibition was reached at 250 nM of MitoQ (arrow). All data are shown as means ± SEM. * P < 0.05, ** P < 0.01, *** P < 0.001 by one-way ANOVA with Dunnett’s multiple comparisons test.

[0123] Figure 2. MitoTEMPO does not dose-dependently reduce the oxygen consumption rate of human breast cancer cells. Fig. 2A and Fig. 2B show the oxygen consumption rate (OCR) of 5,000 MCF7 cells (human breast cancer cells) treated with increasing doses of MitoTEMPO for 24 h. The oxygen consumption was measured using Seahorse oximetry. Fig 2A represents total OCR measurements over time. Fig. 2B shows the basal mitochondrial OCRs (mtOCRs) calculated from the Seahorse traces (n = 6). MitoTEMPO did not inhibit basal mtOCR. Fig. 2C and Fig. 2D Same as in Fig. 2A and 2B, but assessing 10,000 MDA-MB-231 cells (n = 5-6) (also human breast cancer cells). Fig. 2D All data are shown as means ± SEM. All data are shown as means ± SEM. * P < 0.05, ** p < 0.01, *** P < 0.001 by one-way ANOVA with Dunnett’s multiple comparisons test.

[0124] Figure 3. SKQ1 does not dose-dependently reduce the oxygen consumption rate of human breast cancer cell lines MCF7 and MDA-MB-231. Fig. 3A and Fig. 3B show oxygen consumption rate (OCR) of 5,000 MCF7 cells (human breast cancer cells) treated with increasing doses of SKQ1 for 24 h. The oxygen consumption was measured using Seahorse oximetry. Fig 3A represents total OCR measurements over time. Fig. 3B shows the basal mitochondrial OCRs (mtOCRs) calculated from the Seahorse traces (n = 6). SKQ1 did not inhibit basal mtOCR. Fig. 3C and Fig. 3D Same as in Fig. 3 A and 3B, but assessing 10,000 MDA-MB-231 cells (n = 6) (also human breast cancer cells). All data are shown as means ± SEM. All data are shown as means ± SEM. * P < 0.05, ** p < 0.01 by one-way ANOVA with Dunnett’s multiple comparisons test.

[0125] Figure 4. MitoQ dose-dependently reduces the oxygen consumption rate of other human cancer cells. Fig. 4A and Fig. 4B show oxygen consumption rate (OCR) of 5,000 SiHa cells (human cervix cancer cells) treated with increasing doses of MitoQ for 24 h. The oxygen consumption was measured using Seahorse oximetry. Fig 4Arepresents total OCR measurements over time. Fig. 4B shows the basal mitochondrial OCRs (mtOCRs) calculated from the Seahorse traces (n = 4). Fig. 4C and Fig. 4D Same as in Fig. 4A and 4B, but assessing 5,000 PC3 cells (human prostate cancer cells) (n = 4). Fig. 4D Full mtOCR inhibition was reached at 250 nM of MitoQ (arrow). Fig. 4E and Fig. 4F Same as in Fig. 4A and 4B, but assessing 5,000 HCT116 cells (human prostate cancer cells) (n = 4). Fig. 4F Full mtOCR inhibition was reached at 250 nM of MitoQ (arrow). All data are shown as means ± SEM. * P < 0.05, ** P < 0.01, *** P < 0.001 by one-way ANOVA with Dunnett’s multiple comparisons test.

[0126] Figure 5. MitoQ induces a glycolytic switch in human breast cancer cells. Fig. 5A and Fig. 5B present glucose consumption rates, measured in MCF7 cells pretreated for 24 h ± 500 nM of MitoQ (n = 6). Fig. 5A shows that glucose consumption was increased in cells treated with MitoQ compared to control. Fig. 5B shows that lactate release was increased in cells treated with MitoQ compared to control. Fig. 5C and Fig. 5D MCF7 cells were treated with 500 nM of MitoQ for 24h, and subjected to cell fractionation. Mitochondrial and cytosolic ATP were measured using a fluorescence assay and are reported in Fig. 5C and Fig. 5D, respectively (n = 3). Fig. 5E and Fig. 5F present glucose consumption rates, measured in MDA-MB-231 cells pretreated for 24 h ± 250 nM of MitoQ (n = 6). Fig. 5F shows that glucose consumption was increased in cells treated with MitoQ compared to control. Fig. 5G shows that lactate release was increased in cells treated with MitoQ compared to control. Fig. 5G and Fig. 5H MDA- MB-231 cells were treated with 250 nM of MitoQ for 24h, and subjected to cell fractionation. Mitochondrial and cytosolic ATP were measured using a fluorescence assay and are reported in Fig. 5G and Fig. 5H, respectively (n = 3). All data are shown as means ± SEM.

[0127] Figure 6. MitoQ radiosensitizes hypoxic human breast cancer cell in vitro. MCF7 human breast cancer cells were treated ± 500 nM of MitoQ for 24 h under normoxia (21% 02) or hypoxia (1% 02). On the next day, cells are irradiated at increasing doses. Fig. 6A and Fig. 6B. Cells are maintained under normoxia or hypoxia until surviving fractions are determined 7 days post irradiation (n = 5) and are presented in Fig. 6A. while Fig. 6B displays the irradiation dose necessary to kill 10% of the cells(LD10) for day 7. Fig. 6C MCF7 cells are pretreated ± 500 nM of MitoQ for 24 h, irradiated at increasing doses, and tested for clonogenicity. The graph shows the surviving fraction as a function of the irradiation dose (n = 3). Fig. 6D and Fig. 6E As in Fig. 6A and Fig. 6B but using MDA-MB-231 human breast cancer cells treated ± 250 nM of MitoQ (n = 5-6). Fig. 6F As in Fig. 6C but using MDA-MB-231 cells treated ± 250 nM of MitoQ (n = 3). All data are shown as means ± SEM. ns P > 0.05, ** P < 0.01 compared to the normoxic control; # P > 0.05, ### P < 0.001 compared to hypoxia alone; by oneway ANOVA with Tukey’s multiple comparisons test (Fig. 6A and Fig. 6B) or Student’s t test (Fig. 6D and Fig. 6E).

[0128] Figure 7. MitoQ increases MDA-MB-231 spheroid oxygenation. Spheroids are grown in collagen using MDA-MB-231 and HIF-TK-eYFP infected cells. They are then treated ± 500 nM MitoQ for 24 h. Fig. 7A MitoQ does not significantly change spheroid size (n= 8). Fig. 7B presents a quantification of eYFP expression reporting on HIF activity (a marker of hypoxia) in the spheroids (n = 8). MitoQ reduced HIF activity in the spheroids compared to control. All data are shown as means ± SEM. ns P > 0.05, ** P < 0.01, by Student’s t test (b, c).

[0129] Figure 8. MitoQ reduces tumor hypoxia in human breast tumors in mice. Human breast human breast cancer cells are implanted orthotopically in the breast of immunodeficient mice. When the average tumor volume reaches 100 mm3(Day -1), mice are randomly assigned to a treatment group. On Day -1, MDA-MB-231 -bearing mice receive MitoQ (18 mg / Kg per os) or not. On Day 0, all mice receive an intraperitoneal injection of pimonidazole, a marker of hypoxia (60 mg / kg). Mice are sacrificed 90 min later. Fig- 8 shows the reduction in size of the pimonidazole area, each dot represents a mouse tumor (n = 8-10, scale bars = 500 pm). MitoQ reduced the size of the pimonidazole marked area.

[0130] Figure 9. MitoQ radiosensitizes human breast tumors in mice. Human breast human breast cancer cells are implanted orthotopically in the breast of immunodeficient mice. When the average tumor volume reaches 100 mm3 (Day -1), mice are randomly assigned to a treatment group. Fig. 9A and Fig. 9B On Day-1, MDA-MB-231 -bearing mice receive MitoQ (18 mg / Kg per os) or not (n = 7-8 per group). On Day 0, a local 5Gy or a sham irradiation is delivered to mice. Fig. 9A shows tumor growth over time. The dashed line indicates a doubling of the tumor volume. Fig. 9B shows tumor doubling times. Fig. 9C MDA-MB-231 tumor-bearing mice receive MitoQ (18 mg / Kg per os) for 5 consecutive days (from Day -1 to Day +3; 5 doses in total) or not. Radiotherapy or sham irradiation is delivered 24 h after each dose of MitoQ, i.e., from Day 0 to Day+4 (5 x 2 Gy). The graph shows tumor growth over time (n = 8-9 per group). The dashed line indicates a doubling of the tumor volume. All data are shown as means ± SEM. ns P > 0.05, *** P < 0.001 compared to 0 Gy; ## P > 0.01 compared to MitoQ without irradiation; $ P < 0.05 compared to irradiation without MitoQ; by one-way ANOVA with Tukey’s multiple comparisons test (Fig. 9B).EXAMPLES

[0131] The present invention is further illustrated by the following examples.Materials and Methods

[0132] Cells and cell culture. MCF-7 (ATCC, catalog #HTB-22) and MDA-MB-231 (ATCC, catalogue #HTB-26) human breast adenocarcinoma cancer cells, SiHa human cervix cancer cells (ATCC, catalog #HTB-35), PC3 human prostate cancer cells (ATCC, catalog #CRL-1435) and HCT116 human colon cancer cells (ATCC, catalog #CCL-247) were cultured at 37°C in a 5% CO2 humidity-controlled incubator in DMEM containing GlutaMAX, 4.5 g / L D-glucose without pyruvate (ThermoFisher Scientific, catalogue #10566016), supplemented with 10% FBS (Sigma-Aldrich). Cell authenticities were routinely verified with short tandem repeat (STR) testing (Eurofins Genomics).

[0133] Cell treatments and numbering. Where indicated, cells were treated with Mitoquinol mesylate (sold under commercial name MitoQ, produced as previously described in Kelso et al. “ Selective targeting of a redox-active ubiquinone to mitochondria within cells: antioxidant and antiapoptotic properties’". J Biol Chem 276, 4588-4596 (2001)), or (2-(2,2,6,6-tetramethylpiperidin-l-oxyl-4-ylamino)-2-oxoethyl)triphenylphosphonium chloride (MitoTEMPO; Sigma Aldrich , catalog #SML0737) or Visomitin (SKQ1; MedChemExpress, catalog #HY-100474). Hypoxia (1% 02) was achieved by a 24 h incubation in a Whitley H35 hypoxystation (Don Whitley Scientific). Subconfluent cells were irradiated at a dose rate of 0.8 Gy / min using an IBL- 637 137Cs y-ray irradiator (Gamma Service Medical), and spheroids at a dose rate of 2.132 Gy / min using a RS-2000 225 kV irradiator (Rad Source). Cell numbers were determined on a SpectraMax i3x spectrophotometer equipped with a MiniMax imaging cytometer (Molecular Devices).

[0134] Seahorse oximetry and pH-metry, Cellular oxygen consumption rates (OCRs) and extracellular acidification rates (ECARs) were determined on a Seahorse XFe96 bioenergetic analyzer using the XF cell MitoStress kit (Agilent Technologies), according to the manufacturer’s protocol. Briefly, 10,000 MCF-7, SiHa, PC3 or HCT116 cells or 5,000 MDA-MB-231 cells / well were seeded in XF96 culture plates in their regular culture medium ± MitoQ, MitoTEMPO or SKQ1. The next day, culture medium was replaced by DMEM containing 10 mM glucose, 2 mM glutamine, 1.85 g / L NaCl, 3 mg / L phenol red, pH 7.4. Cells were incubated for 1 h in a CO2-free incubator before analysis. Basal OCR was calculated by subtracting OCR after the addition of 0.5 pM of Complex I inhibitor rotenone together with 0.5 pM of Complex III inhibitor antimycin A from OCR without treatment; maximal OCR by subtracting OCR after the addition of rotenone and antimycin A from OCR after the addition of 1 pM of ionophore carbonyl cyanide-4- (trifluoromethoxy)phenylhydrazone (FCCP), and ATP -linked OCR by subtracting OCR without any treatment from OCR after the addition of 1 pM of ATP synthase inhibitor oligomycin. All data were normalized to cell numbers determined on a SpectraMax i3x spectrophotometer equipped with a MiniMax imaging cytometer (Molecular Devices).

[0135] Glucose consumption and lactate release assays. Glucose and lactate levels were determined over time in cell supernatant using enzymatic assays on an ISCUSflex CMA600 bioenergetic analyzer (Aurora Borealis). All data were normalized by total protein content using the Protein Assay from Bio-Rad.

[0136] Mitochondrial and cytosolic ATP measurements. Cells (2 x 107 per dish) were pre-treated for 24 h ± MitoQ and for 6 h ± 0.5 pM a combination of Rotenone andAntimycin before cell pellet collection. Mitochondrial fractionation was then performed according to manufacturer’s protocol (ThermoFisher Scientific, catalog #89874), and fractionated proteins were stored frozen until use. ATP levels were measured using a CellTiter-Glo 2.0 Cell Viability Assay (Promega, catalog #G9243) on a SpectraMax i3x spectrophotometer.

[0137] Clonogenic assays. Cells were pre-treated for 24 h ± MitoQ and seeded in 6-well plates (1000 cells / well). Two weeks after, they were fixed and stained for 1 h with 0.5% crystal violet in a 10% ethanol solution. Colonies were washed with water and counted. Results are expressed as surviving fraction (SF), where SF = #colonies / plating efficiency (PE).

[0138] Spheroids. MDA-MB-231 cells were infected with an HBR-6U lentiviral vector expressing enhanced yellow fluorescent protein (eYPF) under the control of six hypoxia- responsive element (HRE) repeats (Addgene plasmid #42621).29 The next day, they were sorted for eYFP expression. After recovery, 5,000 cells / well were plated on day -3, supplemented with 15 pg / ml of rat tail collagen I (ThermoFisher Scientific, catalog #A1048301) on day -2, and allowed to form spheroids. On day 0, spheroids were imaged before MitoQ administration, and treated ± MitoQ. They were imaged again on Day +1, i.e., 24 h after MitoQ administration. All images were captured on a Leica widefield Dmi8 microscope at 5x magnification, quantified using the FIJI ImageJ software with a custom- written script, and analyzed according to a previously described protocol.

[0139] In vivo experiments. All mouse experiments were performed with the approval of UCLouvain Comite d’Ethique pour 1’Experimentation Animale (approval ID: 2020 / UCL / MD / 033) according to national and European animal care regulations. All in vivo experiments were performed on 5-week-old female Rj :NMRI-Foxnl nu / nu mice. Orthotopic tumor implantation was performed under anesthesia (80 mg / kg of ketamine and 8 mg / Kg of xylazine) as previously described. 17 Tumor size was then monitored every two days using an electronic caliper. When average tumor volumes reached 100 mm3 (Day -1), mice were randomly assigned to a treatment group. On that day, MitoQ at a dose 18 mg / kg or an equal volume of saline was administered by gavage to the indicatedanimal subgroups.

[0140] A first series of animals was used to determine tumor pO2 using electron paramagnetic resonance (EPR) oximetry on Day 0 and on Day +1. A previously disclosed protocol was used on mice anesthetized with 3% isoflurane for 10 minutes and maintained at 37°C with 1.5% isoflurane on a heating blanket, with lithium phthalocyanine crystals as the oxygen sensor.15 After EPR oximetry, mice were sacrificed using terminal anesthesia and cervical dislocation. Tumor oxygen concentrations were calculated as a function of the EPR linewidth calibrated to pO2 levels.

[0141] A second series of animals was used to determine tumor hypoxia on Day +1. On that day, mice were given an intraperitoneal injection of 60 mg / kg pimonidazole hydrochloride (MedChemExpress, catalog #HY-105129) in PBS, and sacrificed 90 min later using terminal anesthesia and cervical dislocation. Tumors were collected, fixed in 4% PFA and embedded in paraffin. Tumors were cut using an Epredia HM 355S automated microtome (ThermoFisher Scientific), and 5 pm-thick slices were mounted onto glass slides, deparaffinized, and blocked using 5% bovine serum albumin (BSA) in tris-buffered saline (45 g NaCl, 6.05 g Tris base in 5 L ddH2O, pH 7.2-7.4) with Tween 20. Slides were then stained with an anti-pimonidazole antibody (Hypoxyprobe, catalog #PAb2627) in 1% BSA for 1 h and incubated with an anti-rabbit HRP secondary antibody (Agilent Technologies, catalog #K4003) for 40 min. They were further incubated in a 3,3 '-Diaminobenzidine (DAB) staining solution (Agilent Technologies, catalog #K3468) for 5 min and counterstained with hematoxylin (Agilent Technologies, catalog #S3301) for 5 min. After washing and drying, coverslips were mounted using an automated coverslipper (Sakura Finetek) and imaged using a Panoramic Scan II slide scanner (3D HisTech). Pimonidazole-positive area and total tumor area were quantified using QuPath.

[0142] A third series of animals received a single local 5 Gy or sham irradiation on Day 0, i.e., 24 h after MitoQ treatment. Tumor growth was then monitored over time using an electronic caliper to establish growth delay curves, as previously shown. Tumor doubling times were calculated based on these measurements.

[0143] A fourth series of animals were administered MitoQ daily at a dose 18 mg / Kg form Days 1- to 3 (total = 5 doses), combined with daily 2 Gy or sham irradiations on Days 0 to 4 (total = 5 doses). Tumor growth was then monitored over time using an electronic caliper to establish growth delay curves. Tumor doubling times were calculated based on these measurements.

[0144] Statistics. All results are presented as means ± standard error of the mean (SEM) for n independent observations. Error bars are sometimes smaller than symbols. Outliers were identified using Dixon’ s Q test for all data except for tumor growth delays for which the robust regression followed by outlier identification (ROUT) method was used with a 1% Q. Student’s t test and one-way ANOVA with Dunnett’s or Tukey’s post-hoc test were used where appropriate. P < 0.05 was considered to be statistically significant.ResultsExample 1 : MitoQ reduces the oxygen consumption rate of human cancer cells.

[0145] To test whether mitochondrially-target antioxidant compounds could sensitize cancer cells to photon irradiation, we initially selected as main models two human breast cancer cell lines representing different metabolic phenotypes: MCF7 and MDA-MB-231 cells. MitoQ was tested at clinically relevant doses ranging from 62.5 nM to 1 pM, with a readout time of 24 h post-treatment (Fig. 1ABCD). In 2D cultures, MitoQ dose- dependently inhibited the mtOCR of both MCF7 cells (Fig. 1AB) and MDA-MB-231 cells (Fig. 1CD), similarly affecting basal mtOCR, maximal mtOCR and mtOCR linked to ATP production (data not shown). While the smallest tested dose of MitoQ (62.5 nM) already significantly inhibited mitochondrial respiration in both cell lines, full inhibition was achieved at doses of 250 nM and 500 nM for MCF7 (Fig. IB) and MDA-MB-231 (Fig. ID), respectively.

[0146] Based on this observation, we tested whether other mtROS-targeting agents could also inhibit human breast cancer cell respiration. Surprisingly, neither MitoTEMPO (Fig. 2ABCD) nor SKQ1 (Fig. 3ABCD) significantly impacted the basal mtOCR of MCF7cells (respectively, Fig. 2AB and Fig 3AB) or of MDA-MB-231 cells (respectively, Fig. 2CD and Fig 3CD). Similarly, neither MitoTEMPO, nor SKQ1 had any effect on the maximal mtOCR or mtOCR linked to ATP production in either cell lines (data not shown). These data revealed that, among the tested mtROS-targeting agents, only MitoQ can induce metabolic oxygen sparing. Hence, only MitoQ could potentially produce an OEE at clinically relevant doses in the context of radiotherapy.

[0147] To enlarge the scope, we also tested other human cancer cell types. As for MCF7 and MDA-MB-231 cells, MitoQ was capable to inhibit basal mtOCR, maximal mtOCR and mtOCR linked to ATP production in SiHa human cervix cancer (Figure 4AB), PC3 human prostate cancer (Figure 4CD) and HCT116 human colon cancer (Figure 4EF) cells. Full mtOCR inhibition was reached at a MitoQ concentration of 250 nM in both PC3 (Fig. 4D) and HCT116 (Fig. 4F) cell lines. SiHa cells, which are known to be highly oxidative, were comparatively less sensitive to MitoQ-induced respiration inhibition. Overall, all tested human cancer cells responded to MitoQ with a decreased mtOCR.ic switch in human breast cancer cells.

[0148] Cancer cells experiencing OXPHOS defect or inhibition usually try to rescue ATP production through accelerating their glycolytic flux. This was the case for MCF7 cells treated with 500 nM of MitoQ (Fig. 5ABCD). Using enzymatic assays, we observed increased glucose uptake and lactate production (Fig. 5AB) associated with changes in subcellular ATP levels; while mitochondrial ATP levels decreased upon MitoQ treatment (to the same extent as a positive control treatment with 0.5 pM Rotenone + 0.5 pM Antimycin A), cytosolic ATP levels significantly increased (Fig. 5CD). MDA-MB-231 cells treated with 250 nM of MitoQ also accelerated their glycolytic rate (Fig. 5EF) while mitochondrial ATP production decreased but it was not sufficient to prevent a drop in cytosolic ATP levels (Fig. 5GH). Note that end-stage glycolytic switches were similar for MCF7 and MDA-MB-231 cells (comparing Fig. 5B and Fig. 5F), but that the amplitude of the switch was more limited for MDA-MB-231 cells, as they were already highly glycolytic before MitoQ treatment (Comparing Fig. 1A and Fig. IB).

[0149] To better understand the amplitude of the glycolytic switch for individual cancer cell lines, we measured the extracellular acidification rates (ECAR) of cells treated ± MitoQ used at the precise doses that inhibited mtOCR (determined from Fig. 1ABCD and Fig. 4ABDCEF). MitoQ administration increased the ECAR of all cell lines tested, confirming a MitoQ-induced glycolytic switch. In other words, MitoQ-induced glycolytic switch not only in MCF7 and MDA-MB-231, but also in SiHa, PC3 and HCT116 human cancer cells.

[0150] Conclusively, our data showed that MitoQ dose-dependently reduces cancer cell respiration, which involves a compensatory increase in the glycolytic rate.ic human breast cancer cell in vitro

[0151] While MitoQ inhibited mtOCR, it is also known to repress cancer cell clonogenicity through inhibiting mtROS production. Both effects could participate in radiosensitization, which would involve oxygen sparing and the OEE, and a simultaneous inhibition of clonogenic survival and repopulation.

[0152] A potential OEE in response to MitoQ was tested by comparing human breast cancer cells treated with MitoQ under normoxia (21% O2) or hypoxia (1% O2) (Fig. 6ABCDEF). MitoQ sensitized hypoxic MCF7 cells (Fig. 6ABC). At 7 days postirradiation, hypoxia induced radioresistance was abolished by pretreating the cells with MitoQ (Fig. 6A). Indeed, while hypoxia significantly increased the irradiation dose necessary to kill 10% of the cells (LD10), MitoQ reduced the LD10 of hypoxic MCF7 cells down to levels of normoxic cells (Fig. 6B and Fig. 6C). Finally, similar results were seen in MDA-MB-231 cells pretreated with 250 nM of MitoQ (Fig. 6DEF). We therefore concluded that MitoQ can radiosensitize cancer cells through the OEE.ia in human breast cancer cell

[0153] Spheroids are known to have an inner hypoxic core resulting from the respiration of outer cell layers. To test reoxygenation by MitoQ, we used a fluorescent HIF-TK-eYFPconstruct reporting on the activity of hypoxia-inducible factors HIF-1 and HIF-2. MitoQ (250 nM) produced no change in spheroid size after 24 h of treatment (Fig. 7A), but significantly decreased HIF-TK-eYFP fluorescence by around 30% (Fig. 7B).5: MitoQ can radiosensitize human breast tumors in mice

[0154] We finally aimed to test whether MitoQ could radiosensitize orthotopic human breast tumors in mice. We used pimonidazole to quantify tumor hypoxia using immunohistochemistry, which revealed a significant decrease in MDA-MB-231 tumor hypoxia 24 h after MitoQ administration (Fig. 8). This effect was associated with effective tumor radiosensitization to single dose radiotherapy at 5 Gy, with measured tumor doubling times of : 14.9 ± 1.5 days in vehicle-treated mice, 20.1 ± 1.0 days for MitoQ alone (+ 5.2 days, P > 0.05), 23.7 ± 1.8 days with a single dose irradiation of 5 Gy (+ 8.8 days, P > 0.05), and 36.3 ± 5.8 days for the combination treatment (+ 21.4 days, P < 0.005) (Fig. 9AB).

[0155] This prompted us to test radiotherapy in its fractionated clinical mode. Accordingly, MDA-MB-231 tumor-bearing mice were locally irradiated with 1 dose of 2 Gy every day for 5 consecutive days, with or without MitoQ administration as a pretreatment of MitoQ 18 mg / Kg per os 24 h before each irradiation. Measurements of tumor growth clearly evidenced that the combination treatment was more effective than individual treatments (Fig. 9C). Indeed, 100 days after treatment, tumor doubling times were not reached in mice treated with 5 x MitoQ ± 5 x 2 Gy, while mean doubling times were of 11.5 ± 0.6 days in the control group, 19.4 ± 3.3 days in the 5 x MitoQ group (P > 0.05 compared to control), and 52.4 ± 6.8 days in the 5 x 2 Gy group (P < 0.01 compared to control). Whole curve analyses using two-way ANOVA with Tukey’s multiple comparisons test confirmed that the combination treatment was significantly more effective than MitoQ alone (P < 0.001) or fractionated radiotherapy alone (P < 0.01).

Claims

CLAIMS1. A compound for use as a radiosensitizing agent in radiotherapy, characterized in that the compound is selected from formula (I) or (II):wherein Ri, R2, and R3 are the same or different and are independently selected from the group consisting of: substituted or unsubstituted C1-C5 alkyl or H; wherein R4 and Rs are the same or different and independently selected from the group consisting of: H, hydroxyl, carboxyl, amide, unsubstituted or substituted alkyl, unsubstituted or substituted alkenyl and unsubstituted or substituted alkynyl; wherein n is an integer ranging from 2 to 20; or a pharmaceutically acceptable salt thereof.

2. The compound for use according to claim 1, characterized in that the compound is selected from formula (III) or (IV):or a pharmaceutically acceptable salt thereof.

3. A pharmaceutical composition for use as a radiosensitizing agent in radiotherapy; characterized in that the composition comprises or consists of a compound of formula (I) or (II), or a pharmaceutically acceptable salt thereof, or a mixture thereof:wherein Ri, R2, and R3 are the same or different and are independently selected from the group consisting of: substituted or unsubstituted C1-C5 alkyl or H; wherein R4 and Rs are the same or different and independently selected from the group consisting of: H, hydroxyl, carboxyl, amide, unsubstituted or substituted alkyl, unsubstituted or substituted alkenyl and unsubstituted or substituted alkynyl; wherein n is an integer ranging from 2 to 20; or a pharmaceutically acceptable salt thereof.

4. The compound for use according to claim 1 or claim 2, or the pharmaceutical composition for use according to claim 3, characterized in that the compound is of formula (I) or a pharmaceutically acceptable salt thereof.

5. The compound for use according to claim 1 or claim 2, or the pharmaceutical composition for use according to claim 3, characterized in that the compound is of formula (II) or a pharmaceutically acceptable salt thereof.

6. The compound for use, or the pharmaceutical composition for use, according to any of the preceding claims characterized in that the salt is a non-reactive anion selected from the group consisting of: alkyl or aryl sulfonates or nitrates.

7. The compound for use according to claim 1 or claim 2, or the pharmaceutical composition for use according to claim 3, characterized in that it is, or comprises, a mesylate salt of formula (I) or a mesylate salt of formula (II).

8. The compound for use, or the pharmaceutical composition for use according to any of the preceding claims; characterized in that it is for use in a method of sensitizing a patient’s tumor cells to radiation.

9. The compound for use, or the pharmaceutical composition for use according to claim 8; characterized in that it is for use in a method for treating and / or preventing and / or reducing the likelihood of occurrence or re-occurrence of a cancer.

10. The compound for use, or the pharmaceutical composition for use according to claim 9; characterized in that the cancer is selected from the group consisting of: a solid tumor, a childhood solid tumor, a non-solid tumor, a central nervous system (CNS)-associated cancer, a non-central nervous system (non-CNS) associated cancer, a hematologic cancer, bladder cancer, a brain cancer, breast cancer, colon cancer, gastric cancer, glioma, head cancer, leukemia, liver cancer, lung cancer, lymphoma, myeloma, neck cancer, tongue cancer, ovarian cancer, uterine sarcoma, melanoma, testicular cancer, pancreatic cancer, renal cancer, salivary cancer, skin cancer, osteosarcoma, bone cancer stomach cancer, thymic epithelial cancer, and thyroid cancer.

11. The compound for use, or the pharmaceutical composition for use according to claim 9; characterized in that the cancer is not a glioma.

12. The compound for use or the pharmaceutical composition for use according to any of the preceding claims; characterized in that the compound or composition is for administration prior to, or during, exposition to a unit dose of radiation.

13. The compound for use, or the pharmaceutical composition for use according to any of the preceding claims; characterized in that the compound or composition is for intravenous administration, subcutaneous administration, in situ administration, intraperitoneal administration or oral administration.

14. The pharmaceutical composition for use according to any of the preceding claims ; characterized in that the pharmaceutical composition further comprises an anticancer agent, in particular selected from the list consisting of an alkylating agent, a platinum preparation, a metabolism antagonist, a topoisomerase inhibitor, a microtubular inhibitor, an anti-cancerous antibiotic, a molecular target drug, a hormone preparation, an immunomodulation drug, an interferon, an interleukin, a plant-derived anticancer agent, and a BRM preparation including immunotherapy agents such as cytokines, cancer treatment vaccines, or antibodies.

15. An in vitro method for radiosensitizing a cancer cell, or composition thereof, comprising steps of: a) providing a cancer cell or preparation thereof; b) bringing into contact the cell or preparation with a compound of formula (I) or(II);wherein Ri, R2, and R3 are the same or different and are independently selected from the group consisting of: substituted or unsubstituted C1-C5 alkyl or H;wherein R4 and Rs are the same or different and independently selected from the group consisting of: H, hydroxyl, carboxyl , amide, unsubstituted or substituted alkyl, unsubstituted or substituted alkenyl and unsubstituted or substituted alkynyl, wherein n is an integer ranging from 2 to 20; or a pharmaceutically acceptable salt thereof; c) administering a unit dose of radiation to the cell or preparation thereof, steps b) and c) being sequential or simultaneous.

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