Agents for cleaving labels from biomolecules in vivo

Abstract

Disclosed herein are compounds comprising trans-cyclooctene moieties, combinations, and kits that can be used to more quickly remove radionuclides from a subject, preferably a human being. Said compounds, combinations and kits can also be used to increase the tumor-to-blood ratio, or to more rapidly and / or conveniently achieve such an increase, of a label in targeted imaging or targeted radiotherapy in a subject, preferably a human being.

Description

[0001] Title: AGENTS FOR CLEAVING LABELS FROM BIOMOLECULES IN

[0002] VIVO

[0003] Field of the invention

[0004] The invention relates to compounds, combinations, and kits for the cleaving of imaging or radiotherapy labels from (bio)molecules in a subject, such as

[0005] (bio)molecules that are administered to said subject for purposes such as targeted imaging and targeted radiotherapy.

[0006] Background of the invention

[0007] In many areas of medical diagnostics, imaging and radiotherapy, it is desired to selectively deliver an agent, such as a radiotherapeutic agent or a diagnostic (e.g. imaging) agent, to a specific site, or a confined region, in the body of a subject such as a patient. Targeting of an organ or a tissue is typically achieved by the conjugation of the desired imaging or radiotherapy label (i.e. a radionuclide) to a targeting agent, which binds to cell surfaces or promotes cellular uptake at or near the target site of interest. The targeting agents used to target such labels are typically constructs that have affinity for cell surface targets (e.g., membrane receptors), structural proteins (e.g., amyloid plaques), or intracellular targets (e.g., RNA, DNA, enzymes, cell signaling pathways). These targeting agents can be antibodies (and fragments), proteins, aptamers, oligopeptides, oligonucleotides, oligosaccharides, as well as peptides, peptoids and organic drug compounds known to accumulate at a particular disease or malfunction. Alternatively, an imaging or radiotherapy agent may target a metabolic pathway, which is upregulated during a disease (like infection or cancer) such as DNA, protein, and membrane synthesis and carbohydrate uptake. In diseased tissues, abovementioned markers can discriminate diseased cells from healthy tissue and offer unique possibilities for early detection, specific diagnosis and (targeted) therapy.

[0008] As radio-imaging and radiotherapeutic agents (i.e. nuclear imaging and therapy agents) comprise radionuclides, which are radioactive, it is desired to quickly, efficiently, and / or conveniently reduce the amount of radionuclides in a patient once its therapeutic and / or imaging purposes are fulfilled. For example, this will enable reducing the dose of potentially harmful radiation given to the whole body. Also, in the context of imaging, clearing the radionuclides from the patient as quickly as possible after the imaging procedure, allows starting another imaging procedure in the same patient of the same or a different imaging target (i.e. image cycling). Natural clearance, however, is very slow.

[0009] Furthermore, an important criterion for successful imaging / therapy agents in general and nuclear imaging / therapy agents in particular is that they exhibit a high target uptake while showing an efficient clearance (through renal and / or hepatobiliary systems) from non-target tissues and from the blood. However, this is often problematic, especially when using antibodies. For example, imaging studies in humans have shown that the maximum concentration of a radiolabeled antibody at the tumor site is attainable within 24 h but several more days are required before the concentration of the labeled antibody in circulation decreases to levels low enough for successful imaging to take place. In the context of radioimmunotherapy (RIT), the slow antibody clearance from blood results in high radiation doses to e.g. the bone marrow limiting the amount of radioactivity that can be safely administered, limiting the therapeutic effect.

[0010] Further, targeted imaging (e.g. optical or nuclear) or radiotherapy can be hampered by circulating fractions of the receptor that is being targeted, and which can capture the imaging or radiotherapy agents before they can reach the target receptor at the target cell surface, negatively impacting target-background ratios.

[0011] In addition, off target uptake of imaging agents (e.g. in the liver) can obscure the target uptake.

[0012] Effectively, the targeting process can be divided into three processes: (I) the administration process, in which the compound comprising a targeting agent is administered to a subject, and a fraction of said compound binds to the target;

[0013] (II) the clearance process, wherein the fraction of the compound comprising a targeting agent that circulates in the blood (rather than being bound to the target) is cleared (i.e. removed by excretion) from the blood and other non-target tissues;

[0014] (III) the imaging / therapy process, wherein the compound comprising a targeting agent present in the subject is used for imaging or therapy purposes.

[0015] It will be understood that the tumor-to-blood (T / B) ratios are increased in process (I) due to targeting, viz. the labelled compound accumulates at the targeted site, in this case a tumor.

[0016] For process (III), the T / B ratio should be sufficiently high, so that the fraction of circulating administered compound or compound bound to non-target tissues does not interfere with the imaging / therapy. Typically, this is achieved by waiting for an undesired long time during process (II), for reasons given above.

[0017] In general, it is desired to have methods to increase target-non target ratio of imaging or radiotherapy agents in the abovementioned process (II) more quickly, and to have temporal and spatial control over the action of those agents.

[0018] The poor T / B ratios for antibodies have led to pre-targeting approaches to improve image quality in radioimmunoimaging and to increase the therapeutic index in RIT. The long-circulating monoclonal antibody (mAh) is administered first, allowed to bind the tumor and slowly clear from circulation, after which a small radiolabeled probe is injected. This probe binds the tumor-bound antibody or otherwise rapidly clears from circulation, leading to improved T / B ratios.

[0019] Typically, a clearing agent is administered prior to injection of the probe, to clear any freely circulating antibody from blood, resulting in further improved T / B ratios [F.C. van de Watering et al., Front. Med. 2014, 1, 44] However, pretargeting can typically only be used with non-internalizing receptors, and is relatively complex, requiring the optimization of dosing and timing for three agents. An alternative approach is to administer a clearing agent to remove a radiolabeled antibody from circulation after sufficient amounts have bound the target, but this has not worked well in the clinic and gives high radiation doses to the liver [R.H.J. Begent et al., Br. J. Cancer 1989, 60, p. 406-412]

[0020] Another approach is to cleave the radiolabel from freely circulating antibody after sufficient amounts of radiolabeled antibody have bound and internalized in the target cells by of administering an enzyme designed to cleave the bond between antibody and label. However, the enzymatic cleavage method was rather slow and inefficient, giving only 3-fold improvements in T / B ratios [Q. Ren et al., Mol. Pharm. 2019, 16, p. 1065-1073]. In addition, three injections with the enzyme were typically required, which makes it an inconvenient method.

[0021] It is a desire to provide compounds and / or a combination of compounds that enables to quickly reduce the amount of radionuclides in a patient, e.g. after radioimaging is completed. It is also desired that a compound and / or a

[0022] combination of compounds be provided that enables an increase of the target-non target ratio of imaging or radiotherapy agents in the clearance process. It is also desired that this increase is obtained faster than in known methods.

[0023] Furthermore, it is desired to provide a compound and / or a combination of compounds that enables temporal and spatial control over the action of those agents. In addition, it is desired that this compound and / or a combination of compounds is versatile, rapid, efficient, and / or convenient.

[0024] Summary of the invention

[0025] The invention, in one aspect, pertains to a compound satisfying Formula (1):

[0026]

[0027] Formula (1);

[0028] and pharmaceutically acceptable salts thereof, wherein each X1, X2, X3, X4is independently selected from the group consisting of

[0029] -C(R47)2-, -NR37-, -C(O)-, -O-, such that at most two of X1, X2, X3, X4are not -C(R47)2-, and with the proviso that no sets consisting of adjacent atoms are present selected from the group consisting of -O-O-, -O-N-, -C(O)-O-, N-N-, and -C(O)-C(O)-;

[0030] X5is -C(R47)2- or -CHR48, preferably X5is -C(R47)2-;

[0031] each R48is independently selected from the group consisting of -LB, and -LA; preferably R48is -LB;

[0032] R48is bound to the remainder of the compound of Formula (1) via a part of R48that is -O-, -S-, -OC(O)-, -OC(S)-, -SC(O)-, or -SC(S)-;

[0033] LBis a moiety satisfying Formula (2):

[0034] Formula (2); wherein

[0035] the dashed line denotes a bond to the remainder of the compound of Formula (1); SLis a linker, which optionally is a self-immolative linker LC;

[0036] each R98individually is a Label or a clearance- directing group;

[0037] each d independently is 0 or 1;

[0038] e is an integer in a range of from 0 to 4, preferably e is 0;

[0039] the Label is a moiety comprising a radionuclide;

[0040] the compound of Formula (1) comprises at least one Label and at least one Administration Agent;

[0041] LAis a moiety satisfying Formula (3):

[0042] Formula (3); wherein

[0043] the dashed line denotes a bond to the remainder of the compound of Formula (1); each s is independently 0 or 1; preferably each s is 0;

[0044] i is an integer in a range of from 0 to 4, preferably 0 or 1, most preferably 0;

[0045] each SPindependently is a spacer, which optionally is a self-immolative linker LC; AAdenotes an Administration Agent, which is an antibody;

[0046] CCdenotes a Construct-C, wherein each Construct-C is independently selected from the group consisting of a Label and an Administration Agent; preferably the compound of Formula (1) comprises at most one CC;

[0047] provided that LAonly comprises both the Label and the Administration Agent when LAis R48;

[0048] provided that if LAbeing R48comprises both the Label and the Administration Agent, then the SPlinked to said Label and said Administration Agent is a self- immolative linker;

[0049] each R47is independently selected from the group consisting of

[0050] hydrogen, -LB, -LA, -(SP)i-CC, -F, -Cl, -Br, -I, -OR37, -N(R37)2, -SO3, -PO3-, -NO2, - CF3, -SR37, S(=O)2N(R37)2, OC(=O)R37, SC(=O) R37, OC(=S)R37, SC(=S)R37, NR37C(=O)-R37, NR37C(=S)-R37, NR37C(=O)O-R37, NR37C(=S)O-R37,

[0051] NR37C(=O)S-R37, NR37C(=S)S-R37, OC(=O)N(R37)2, SC(=O)N(R37)2,

[0052] OC(=S)N(R37)2, SC(=S)N(R37)2, NR37C(=O)N(R37)2, NR37C(=S)N(R37)2, C(=O)R37,C(=S)R37,C(=O)N(R37)2, C(=S)N(R37)2, C(=O)O-R37, C(=O)S-R37, C(=S)O-R37, C(=S)S-R37, S(O)R37, -S(O)2R37, NR37S(O)2R37, -ON(R37)2,-NR37OR37, C1-C24alkyl groups, C2-C24alkenyl groups, C2-C24alkynyl groups, C6-C24aryl groups, C2-C24heteroaryl groups, C3-C24cycloalkyl groups, C5-C24cycloalkenyl groups, C12-C24cycloalkynyl groups, C3-C24(cyclo)alkyl(hetero)aryl groups, C3-C24(hetero)aryl(cyclo)alkyl, C4-C24(cyclo)alkenyl(hetero)aryl groups, C4-C24

[0053] (hetero)aryl(cyclo)alkenyl groups, C4-C24(cyclo)alkynyl(hetero)aryl groups, C4- C24(hetero)aryl(cyclo)alkynyl groups, C4-C24alkylcycloalkyl groups, and C4-C24cycloalkylalkyl groups; wherein i is an integer in a range of from 0 to 4, preferably i is an integer ranging from 0 to 1,

[0054] wherein the alkyl groups, alkenyl groups, alkynyl groups, aryl, heteroaryl, cycloalkyl groups, cycloalkenyl groups, cycloalkynyl groups,

[0055] (cyclo)alkyl(hetero)aryl groups, (hetero)aryl(cyclo)alkyl groups,

[0056] (cyclo)alkenyl(hetero)aryl groups, (hetero)aryl(cyclo) alkenyl groups, (cyclo)alkynyl(hetero)aryl groups, (hetero)aryl(cyclo)alkynyl groups, alkylcycloalkyl groups, cycloalkylalkyl groups are optionally substituted with a moiety selected from the group consisting of -Cl, -F, -Br, -I, -OR37, -N(R37)2, - SO3R37, -PO3(R37)2, -PO4(R37)2, -NO2, -CF3, =O, =NR37, and -SR37, and optionally contain one or more heteroatoms selected from the group consisting of O, S, NR37, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized;

[0057] two R47and / or R37are optionally comprised in a ring,

[0058] two R47and / or R37are optionally comprised in a ring so as to form a ring fused to the eight membered trans-ring of Formula (1); each R37is independently selected from the group consisting of hydrogen, -LB, - LA, -(SP)i-CC, C1-C24alkyl groups, C2-C24alkenyl groups, C2-C24alkynyl groups, C6-C24aryl groups, C2-C24heteroaryl groups, C3-C24cycloalkyl groups, C5-C24cycloalkenyl groups, C12-C24cycloalkynyl groups, C3-C24(cyclo)alkyl(hetero)aryl groups, C3-C24(hetero)aryl(cyclo)alkyl, C4-C24(cyclo)alkenyl(hetero)aryl groups, C4-C24(hetero) aryl (cyclo) alkenyl groups, C4-C24(cyclo)alkynyl(hetero)aryl groups, C4-C24(hetero) aryl (cyclo) alkynyl groups, C4-C24alkylcycloalkyl groups, and C4- C24cycloalkylalkyl groups; wherein i is an integer in a range of from 0 to 4, preferably i is 1;

[0059] the R37groups not being hydrogen are optionally substituted with a moiety selected from the group consisting of -Cl, -F, -Br, -I, -OH, -NH2, -SO3H, -PO3H,- PO4H2,-NO2, -CF3, =O, =NH, and -SH, and optionally contain one or more heteroatoms selected from the group consisting of O, S, NH, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized.

[0060] In another aspect, the invention relates to a combination comprising the compound according to Formula (1), and a Cleaving Agent, with the proviso that when at least one R48in Formula (1) comprises a Label, then the Cleaving Agent does not comprise the same Label as R48; with the proviso that when at least one R48in Formula (1) comprises an Administration Agent, then the Cleaving Agent does not comprise the same Administration Agent as R48;

[0061] wherein the Cleaving Agent is a diene. In yet another aspect, the invention pertains to the compound according to Formula (1), or the combination according to the invention for use as a

[0062] medicament.

[0063] In yet another aspect, the invention relates to the compound according to Formula (1), or the combination according to the invention, for use in the treatment of a disease, preferably cancer, in a subject, preferably a human, wherein the treatment is radiotherapy.

[0064] In a further aspect still, the invention relates to the compound according to Formula (1), or the combination according to the invention, for use in a diagnostic method comprising the steps of

[0065] (a) administering a compound according to Formula (1) as defined herein, to a subject, preferably a human;

[0066] (b) administering a Cleaving Agent as defined herein, to said subject;

[0067] (c) imaging the compound according to Formula (1) present in the subject to collect data;

[0068] (d) comparing said data to standard values;

[0069] (e) finding a significant deviation from said standard values during comparison;

[0070] (f) attributing the significant deviation to a particular clinical picture, preferably to cancer.

[0071] In yet another aspect, the invention pertains to a non-therapeutic method for imaging a compound according to Formula (1) in a subject, preferably a human, said non-therapeutic method comprising the steps of

[0072] (a) administering a compound according to Formula (1) as defined herein, to the subject;

[0073] (b) administering a Cleaving Agent as defined herein, to said subject;

[0074] (c) imaging the compound according to Formula (1) present in the subject.

[0075] In yet a further aspect, the invention relates to a use of a compound according to Formula (1), or a combination according to the invention, for imaging in a subject, preferably a human. Brief Description of the Figures

[0076] Figure 1. General scheme depicting the use of the invention in radioimmunotherapy. A radiolabelled antibody is administered, allowed to circulate and bind an internalizing cancer receptor, and after sufficient internalization has occurred a Cleaving Agent is administered that cleaves the radiolabel (e.g. a moiety comprising a radiometal-chelate complex) from the antibody, resulting in rapid renal clearance of the radioactivity from blood and non-target tissues, but not of the tumor cell-internalized radioactivity.

[0077] Figure 2. Radioactivity profiles in blood in mice injected with a mAb-trigger- Label conjugate followed by a Cleaving Agent or by vehicle. The Cleaving Agent is administered one hour or 24 hours post-mAb injection. The figure shows rapid clearance of the Label from blood upon trigger reaction with the Cleaving Agent in vivo.

[0078] Detailed Description of the Invention

[0079] In a broad sense, the invention pertains to the judicious recognition that compounds according to Formula (1), and combinations and kits as defined herein, better address one or more of the abovementioned desires. The

[0080] compounds, combinations, and kits of the invention can be used to quickly lower the amount of radionuclides in a subject. In particular, the compounds,

[0081] combinations, and kits of the invention can be used to increase the target-non target ratio of imaging or radiotherapy agents in the clearance process, and more particularly to reach such an increase more rapidly.

[0082] The invention, in one aspect, presents the concept of administering a compound according to Formula (1) comprising a label (a moiety comprising a radionuclide) and an Administration Agent, and subsequently administering a Cleaving Agent comprising a diene in the clearance phase, said dienophile and diene being capable of undergoing a bio-orthogonal reaction with each other, resulting in the decoupling of the label from the Administration Agent, preferably at specifically the non-targeted site ( e.g . the blood), and the efficient clearance of the released label from circulation and other non-target tissues, and / or the body as a whole. An Administration Agent is to be understood as any antibody, in particular those of which it is desired to image its biodistribution or target binding in vivo, or which is used as a targeting agent for therapeutic radiation.

[0083] This bio-orthogonal reaction is very fast, and readily results in good release of the moiety comprising a radionuclide. Typically, high release yields are obtained after only one administration of the Cleaving Agent, making the method efficient, and convenient for both the patient and the medical practitioner.

[0084] Thus, preferably the cleavage of the label from the compound of Formula (1) pertains to the fraction present in, or bound to non-target tissues while the portion bound to target tissues is not cleaved or does not lead to accelerated clearance.

[0085] The fact that the inverse electron demand Diels-Alder (IEDDA) reaction can be used in the abovementioned applications is surprising. Firstly, the IEDDA reaction has never been used to lower the amount of radionuclides in a subject. Instead, the IEDDA reaction has typically been used to specifically release a drug at a target site, after which the drug entered a cell, a tumor, and the like. Thus, this does not relate to radionuclides, and speaks against ways to quickly remove the released agent from the body. In addition, previously the IEDDA reaction was used to specifically release a drug at the target site specifically after the clearance process. Moreover, the IEDDA reaction was used in applications wherein no release occurs, but a clearance- directing group is used to remove the Administration Agent from circulation. By contrast, the present invention is based on the judicious insight that with the compounds and combinations of the invention, decoupling of a label and the Administration Agent occurs, preferably in the blood and other non-target sites, after which specifically the label is rapidly cleared (Figure 1).

[0086] Without wishing to be bound by theory, the inventors believe that an antibody comprised in the compounds of Formula (1) has a relatively slow clearance rate due large size and / or the binding to biomolecules and much larger structures, such as cells, which greatly reduces the clearance rate of the compound of Formula (1). By addition of a Cleaving Agent, the moiety comprising a radionuclide is released. Said moiety is by definition smaller than the compound of Formula (1), and has no specific affinity for any biomolecule and thus typically does not bind to such a biomolecule. The inventors believe that for at least these reasons, the released moiety is cleared much faster than the compound of Formula (1).

[0087] Specifically, when the Administration Agent is an intact IgG antibody, this antibody will clear very slowly from blood due to FcRn-mediated recycling. In addition, or alternatively, Administration Agents may bind to a Primary Target present in blood (e.g. on a blood cell or a shed receptor from a tumor) or other biomolecules (e.g. serum albumin) and tissues, target tissues and non-target tissues, and as a result clear slowly from the body as a whole, from the target tissues or from the non-target tissues. Also, proteins in general, including antibodies, can clear slowly due to relatively large size. On the contrary, the released moiety comprising a radionuclide is generally cleared fast, as it is much smaller and typically has low affinity to biomolecules and tissues. Reference is made to [Orcutt et al, Mol Imaging Biol. 2011, 215-221] demonstrating the fast clearance of radiolabeled chelate derivatives.

[0088] Thus, in some embodiments, a compound of Formula (1) comprising a label, particularly a radiolabeled chelate, and an Administration Agent, will be administered for the purpose of being targeted to and internalized by a certain tissue in the body, e.g. a tumor cell receptor or a brain target (Figure 1).

[0089] Subsequent injection of Cleaving Agent, preferably a non-internalizing (i.e. not cell permeable) Cleaving Agent, results in release of the radiolabeled chelate from Administration Agent in circulation and its rapid excretion, while any released chelate inside the target cell will not be excreted, leading to increased target-non-target (T-NT) ratios, that in particular are achieved more rapidly than with known methods.

[0090] In other embodiments, the compound of Formula (1) targets a non- internalizing receptor in a tissue. Then, preferably the Cleaving Agent is chosen such that it does not significantly extravasate from blood into other tissues, to enable specific release of the Label in the blood, i.e. off-target.

[0091] The compound of Formula (1) can be specifically designed as an imaging agent of a particular target or process in vivo, such as in the case of radioimmunoimaging. It can also be specifically designed to deliver therapeutic radiation to a particular target in vivo, such as in the case of

[0092] radioimmunotherapy.

[0093] A Cleaving Agent is an agent or compound that is administered to a subject for the purpose of cleaving the label from the Administration Agent resulting in a different biodistribution and pharmacokinetics of the released label compared to the label when bound to the Administration Agent. The released label has a much faster blood clearance than the compound of Formula (1) and / or the released label has a much lower retention in one or more non-target tissues such as epithelial cells, fat, muscle, and kidney and RES organs such as liver and spleen, than the compound of Formula (1).

[0094] The concept of cleaving a compound of Formula (1) in vivo is of general relevance in targeted radiotherapy and imaging.

[0095] Definitions

[0096] The present invention will further be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims. Any reference signs in the claims shall not be construed as limiting the scope. The drawings described are only schematic and are non-limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn on scale for illustrative purposes. Where an indefinite or definite article is used when referring to a singular noun e.g. "a" or "an", "the", this includes a plural of that noun unless something else is specifically stated.

[0097] The verb "to comprise", and its conjugations, as used in this description and in the claims is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. Thus, the scope of the expression "a device comprising means A and B" should not be limited to devices consisting only of components A and B. It means that with respect to the present invention, the only relevant components of the device are A and B.

[0098] In addition, reference to an element by the indefinite article "a" or "an" does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there is one and only one of the elements. The indefinite article "a" or "an" thus usually means "at least one".

[0099] The compounds disclosed in this description and in the claims may comprise one or more asymmetric centres, and different diastereomers and / or enantiomers may exist of the compounds. The description of any compound in this description and in the claims is meant to include all diastereomers, and mixtures thereof, unless stated otherwise. In addition, the description of any compound in this description and in the claims is meant to include both the individual enantiomers, as well as any mixture, racemic or otherwise, of the enantiomers, unless stated otherwise. When the structure of a compound is depicted as a specific enantiomer, it is to be understood that the invention of the present application is not limited to that specific enantiomer, unless stated otherwise. When the structure of a compound is depicted as a specific

[0100] diastereomer, it is to be understood that the invention of the present application is not limited to that specific diastereomer, unless stated otherwise.

[0101] The compounds may occur in different tautomeric forms. The compounds according to the invention are meant to include all tautomeric forms, unless stated otherwise. When the structure of a compound is depicted as a specific tautomer, it is to be understood that the invention of the present application is not limited to that specific tautomer, unless stated otherwise.

[0102] The compounds disclosed in this description and in the claims may further exist as exo and endo diastereomers. Unless stated otherwise, the description of any compound in the description and in the claims is meant to include both the individual exo and the individual endo diastereomers of a compound, as well as mixtures thereof. When the structure of a compound is depicted as a specific endo or exo diastereomer, it is to be understood that the invention of the present application is not limited to that specific endo or exo diastereomer, unless stated otherwise.

[0103] Unless stated otherwise, the compounds of the invention and / or groups thereof may be protonated or deprotonated. It will be understood that it is possible that a compound may bear multiple charges which may be of opposite sign. For example, in a compound containing an amine and a carboxylic acid, the amine may be protonated while simultaneously the carboxylic acid is

[0104] deprotonated.

[0105] The present invention also provides a combination of a compound of Formula (1) and a Cleaving Agent. The term“combination” is to be understood in broad sense, not limited to a kit comprising both components. Thus, the compound of Formula (1) and the Cleaving Agent can be provided totally separately of each other. It will be understood that the function of the Cleaving Agent in particular is to act in combination with a compound of Formula (1).

[0106] In several formulae, groups or substituents are indicated with reference to letters such as“A”,“B”,“X”,“Y”, and various (numbered)“R” groups. In addition, the number of repeating units may be referred to with a letter, e.g. n in -(CH2)n-. The definitions of these letters are to be read with reference to each formula, i.e. in different formulae these letters, each independently, can have different meanings unless indicated otherwise.

[0107] In several chemical formulae and texts below reference is made to "alkyl", "heteroalkyl", "aryl", “heteroaryl”,“alkenyl”,“alkynyl”,“alkylene”, “alkenylene”,“alkynylene”, "arylene",“cycloalkyl”,“cycloalkenyl”,“cycloakynyl”, arenetriyl, and the like. The number of carbon atoms that these groups have, excluding the carbon atoms comprised in any optional substituents as defined herein, can be indicated by a designation preceding such terms (e.g.“C1-C8alkyl” means that said alkyl may have from 1 to 8 carbon atoms). For the avoidance of doubt, a butyl group substituted with a -OCH3group is designated as a C4alkyl, because the carbon atom in the substituent is not included in the carbon count. Unsubstituted alkyl groups have the general formula CnH2n+1and may be linear or branched. Optionally, the alkyl groups are substituted by one or more substituents further specified in this document. Examples of alkyl groups include methyl, ethyl, propyl, 2-propyl, t-butyl, 1-hexyl, 1-dodecyl, etc. Unless stated otherwise, an alkyl group optionally contains one or more heteroatoms

[0108] independently selected from the group consisting of O, NR36, S, P, and Si, wherein the N, S, and P atoms are optionally oxidized and the N atoms are optionally quaternized. In preferred embodiments, up to two heteroatoms may be consecutive, such as in for example -CH2-NH-OCH3and -CH2-O-Si(CH3)3. In some preferred embodiments the heteroatoms are not directly bound to one another. Examples of heteroalkyls include -CH2CH2-O-CH3, -CH2CH2-NH-CH3, - CH2CH2-S(O)-CH3 ,-CH=CH-O-CH3, -Si(CH3)3. In preferred embodiments, a C1- C4alkyl contains at most 2 heteroatoms.

[0109] A cycloalkyl group is a cyclic alkyl group. Unsubstituted cycloalkyl groups comprise at least three carbon atoms and have the general formula CnH2n-1. Optionally, the cycloalkyl groups are substituted by one or more substituents further specified in this document. Examples of cycloalkyl

[0110] groups include cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl. Unless stated otherwise, a cycloalkyl group optionally contains one or more heteroatoms independently selected from the group consisting of O, NR36, S, P, and Si, wherein the N, S, and P atoms are optionally oxidized and the N atoms are optionally quaternized.

[0111] An alkenyl group comprises one or more carbon-carbon double bonds, and may be linear or branched. Unsubstituted alkenyl groups comprising one C-C double bond have the general formula CnH2n-1. Unsubstituted alkenyl groups comprising two C-C double bonds have the general formula CnH2n-3. An alkenyl group may comprise a terminal carbon-carbon double bond and / or an internal carbon-carbon double bond. A terminal alkenyl group is an alkenyl group wherein a carbon-carbon double bond is located at a terminal position of a carbon chain. An alkenyl group may also comprise two or more carbon-carbon double bonds. Examples of an alkenyl group include ethenyl, propenyl, isopropenyl, t- butenyl, 1,3-butadienyl, 1,3-pentadienyl, etc. Unless stated otherwise, an alkenyl group may optionally be substituted with one or more, independently selected, substituents as defined herein. Unless stated otherwise, an alkenyl group optionally contains one or more heteroatoms independently selected from the group consisting of O, NR36, S, P, and Si, wherein the N, S, and P atoms are optionally oxidized and the N atoms are optionally quaternized.

[0112] An alkynyl group comprises one or more carbon-carbon triple bonds, and may be linear or branched. Unsubstituted alkynyl groups comprising one C-C triple bond have the general formula CnH2n-3. An alkynyl group may comprise a terminal carbon-carbon triple bond and / or an internal

[0113] carbon-carbon triple bond. A terminal alkynyl group is an alkynyl group wherein a carbon-carbon triple bond is located at a terminal position of a carbon chain. An alkynyl group may also comprise two or more carbon-carbon triple bonds. Unless stated otherwise, an alkynyl group may optionally be substituted with one or more, independently selected, substituents as defined herein. Examples of an alkynyl group include ethynyl, propynyl, isopropynyl, t-butynyl, etc. Unless stated otherwise, an alkynyl group optionally contains one or more heteroatoms independently selected from the group consisting of O, NR36, S, P, and Si, wherein the N, S, and P atoms are optionally oxidized and the N atoms are optionally quaternized.

[0114] An aryl group refers to an aromatic hydrocarbon ring system that comprises six to twenty-four carbon atoms, more preferably six to twelve carbon atoms, and may include monocyclic and polycyclic structures. When the aryl group is a polycyclic structure, it is preferably a bicyclic structure. Optionally, the aryl group may be substituted by one or more substituents further specified in this document. Examples of aryl groups are phenyl and naphthyl.

[0115] Arylalkyl groups and alkylaryl groups comprise at least seven carbon atoms and may include monocyclic and bicyclic structures. Optionally, the arylalkyl groups and alkylaryl may be substituted by one or more substituents further specified in this document. An arylalkyl group is for example benzyl. An alkylaryl group is for example 4-tert-butylphenyl.

[0116] Heteroaryl groups comprise at least two carbon atoms (i.e. at least C2) and one or more heteroatoms N, O, P or S. A heteroaryl group may have a monocyclic or a bicyclic structure. Optionally, the heteroaryl group may be substituted by one or more substituents further specified in this document.

[0117] Examples of suitable heteroaryl groups include pyridinyl, quinolinyl, pyrimidinyl, pyrazinyl, pyrazolyl, imidazolyl, thiazolyl, pyrrolyl, furanyl, triazolyl,

[0118] benzofuranyl, indolyl, purinyl, benzoxazolyl, thienyl, phospholyl and oxazolyl. Heteroaryl groups preferably comprise five to sixteen carbon atoms and contain between one to five heteroatoms.

[0119] Heteroarylalkyl groups and alkylheteroaryl groups comprise at least three carbon atoms (i.e. at least C3) and may include monocyclic and bicyclic structures. Optionally, the heteroaryl groups may be substituted by one or more substituents further specified in this document.

[0120] Where an aryl group is denoted as a (hetero)aryl group, the notation is meant to include an aryl group and a heteroaryl group. Similarly, an

[0121] alkyl(hetero)aryl group is meant to include an alkylaryl group and an

[0122] alkylheteroaryl group, and (hetero)arylalkyl is meant to include an arylalkyl group and a heteroarylalkyl group. A C2-C24(hetero)aryl group is thus to be interpreted as including a C2-C24heteroaryl group and a C6-C24aryl group.

[0123] Similarly, a C3-C24alkyl(hetero)aryl group is meant to include a C7- C24alkylaryl group and a C3-C24alkylheteroaryl group, and a C3-C24(hetero)arylalkyl is meant to include a C7-C24arylalkyl group and a C3-C24heteroarylalkyl group.

[0124] A cycloalkenyl group is a cyclic alkenyl group. An unsubstituted cycloalkenyl group comprising one double bond has the general formula CnH2n-3. Optionally, a cycloalkenyl group is substituted by one or more substituents further specified in this document. An example of a cycloalkenyl group is cyclopentenyl. Unless stated otherwise, a cycloalkenyl group optionally contains one or more heteroatoms independently selected from the group consisting of O, NR36, S, P, and Si, wherein the N, S, and P atoms are optionally oxidized and the N atoms are optionally quaternized.

[0125] A cycloalkynyl group is a cyclic alkynyl group. An unsubstituted cycloalkynyl group comprising one triple bond has the general formula CnH2n-5. Optionally, a cycloalkynyl group is substituted by one or more substituents further specified in this document. An example of a cycloalkynyl group is cyclooctynyl. Unless stated otherwise, a cycloalkynyl group optionally contains one or more heteroatoms independently selected from the group consisting of O, NR.36, S, P, and Si, wherein the N, S, and P atoms are optionally oxidized and the N atoms are optionally quaternized.

[0126] In general, when (hetero) is placed before a group, it refers to both the variant of the group without the prefix hetero- as well as the group with the prefix hetero-. Herein, the prefix hetero- denotes that the group contains one or more heteroatoms selected from the group consisting of O, N, S, P, and Si. It will be understood that groups with the prefix hetero- by definition contain

[0127] heteroatoms. Hence, it will be understood that if a group with the prefix hetero- is part of a list of groups that is defined as optionally containing heteroatoms, that for the groups with the prefix hetero- it is not optional to contain

[0128] heteroatoms, but is the case by definition.

[0129] Herein, it will be understood that when the prefix hetero- is used for combinations of groups, the prefix hetero- only refers to the one group before it is directly placed. For example, heteroarylalkyl denotes the combination of a heteroaryl group and an alkyl group, not the combination of a heteroaryl and a heteroalkyl group. As such, it will be understood that when the prefix hetero- is used for a combination of groups that is part of a list of groups that are indicated to optionally contain heteroatoms, it is only optional for the group within the combination without the prefix hetero- to contain a heteroatom, as it is not optional for the group within the combination with the prefix hetero- by definition (see above). For example, if heteroarylalkyl is part of a list of groups indicated to optionally contain heteroatoms, the heteroaryl part is considered to contain heteroatoms by definition, while for the alkyl part it is optional to contain heteroatoms.

[0130] Herein, the prefix cyclo- denotes that groups are cyclic. It will be understood that when the prefix cyclo- is used for combinations of groups, the prefix cyclo- only refers to the one group before it is directly placed. For example, cycloalkylalkenylene denotes the combination of a cycloalkylene group (see the definition of the suffix -ene below) and an alkenylene group, not the combination of a cycloalkylene and a cycloalkenylene group.

[0131] In general, when (cyclo) is placed before a group, it refers to both the variant of the group without the prefix cyclo- as well as the group with the prefix cyclo-.

[0132] Herein, the suffix -ene denotes divalent groups, i.e. that the group is linked to at least two other moieties. An example of an alkylene is propylene (- CH2-CH2-CH2-), which is linked to another moiety at both termini. It is understood that if a group with the suffix -ene is substituted at one position with -H, then this group is identical to a group without the suffix. For example, an alkylene substituted with -H is identical to an alkyl group. I.e. propylene, -CH2-CH2-CH2-, substituted with -H at one terminus, -CH2-CH2-CH2-H, is logically identical to propyl, -CH2-CH2-CH3.

[0133] Herein, when combinations of groups are listed with the suffix -ene, it refers to a divalent group, i.e. that the group is linked to at least two other moieties, wherein each group of the combination contains one linkage to one of these two moieties. As such, for example alkylarylene is understood as a combination of an arylene group and an alkylene group. An example of an alkylarylene group is -phenyl-CH2-, and an example of an arylalkylene group is -CH2-phenyl-.

[0134] Herein, the suffix -triyl denotes trivalent groups, i.e. that the group is linked to at least three other moieties. An example of an arenetriyl is depicted below:

[0135]

[0136] wherein the wiggly lines denote bonds to different groups of the main compound.

[0137] It is understood that if a group with the suffix -triyl is substituted at one position with -H, then this group is identical to a divalent group with the suffix -ene. For example, an arenetriyl substituted with -H is identical to an arylene group. Similarly, it is understood that if a group with the suffix -triyl is substituted at two positions with -H, then this group is identical to a monovalent group. For example, an arenetriyl substituted with two -H is identical to an aryl group.

[0138] It is understood that if a group, for example an alkyl group, contains a heteroatom, then this group is identical to a hetero- variant of this group. For example, if an alkyl group contains a heteroatom, this group is identical to a heteroalkyl group. Similarly, if an aryl group contains a heteroatom, this group is identical to a heteroaryl group. It is understood that“contain” and its

[0139] conjugations mean herein that when a group contains a heteroatom, this heteroatom is part of the backbone of the group. For example, a C2alkylene containing an N refers to -NH-CH2-CH2-, -CH2-NH-CH2-, and -CH2-CH2-NH-.

[0140] Unless indicated otherwise, a group may contain a heteroatom at non- terminal positions or at one or more terminal positions. In this case,“terminal” refers to the terminal position within the group, and not necessarily to the terminal position of the entire compound. For example, if an ethylene group contains a nitrogen atom, this may refer to

[0141] -NH-CH2-CH2-, -CH2-NH-CH2-, and -CH2-CH2-NH-. For example, if an ethyl group contains a nitrogen atom, this may refer to -NH-CH2-CH3, -CH2-NH-CH3, and -CH2-CH2-NH2.

[0142] Herein, it is understood that cyclic compounds (i.e. aryl, cycloalkyl, cycloalkenyl, etc.) are understood to be monocyclic, polycyclic or branched. It is understood that the number of carbon atoms for cyclic compounds not only refers to the number of carbon atoms in one ring, but that the carbon atoms may be comprised in multiple rings. These rings may be fused to the main ring or substituted onto the main ring. For example, C10aryl optionally containing heteroatoms may refer to inter alia a naphthyl group (fused rings) or to e.g. a bipyridyl group (substituted rings, both containing an N atom).

[0143] Unless stated otherwise, (hetero)alkyl groups, (hetero) alkenyl groups, (hetero)alkynyl groups, (hetero)cycloalkyl groups, (hetero)cycloalkenyl groups, (hetero)cycloalkynyl groups, (hetero) alky lcycloalkyl groups,

[0144] (hetero)alkylcycloalkenyl groups, (hetero) alky lcycloalkynyl groups,

[0145] (hetero)cycloalkylalkyl groups, (hetero)cycloalkenylalkyl groups, (hetero)cycloalkynylalkyl groups, (hetero)alkenylcycloalkyl groups, (hetero)alkenylcycloalkenyl groups, (hetero)alkenylcycloalkynyl groups,

[0146] (hetero)cycloalkylalkenyl groups, (hetero)cycloalkenylalkenyl groups,

[0147] (hetero)cycloalkynylalkenyl groups, (hetero)alkynylcycloalkyl groups,

[0148] (hetero)alkynylcycloalkenyl groups, (hetero)alkynylcycloalkynyl groups,

[0149] (hetero)cycloalkylalkynyl groups, (hetero)cycloalkenylalkynyl groups,

[0150] (hetero)cycloalkynylalkynyl groups, (hetero)aryl groups, (hetero)arylalkyl groups, (hetero)arylalkenyl groups, (hetero)arylalkynyl groups, alkyl(hetero)aryl groups, alkenyl(hetero)aryl groups, alky nyl(hetero) aryl groups, cycloalkyl(hetero)aryl groups, cycloalkenyl(hetero)aryl groups, cycloalkynyl(hetero)aryl groups,

[0151] (hetero)arylcycloalkyl groups, (hetero)arylcycloalkenyl groups,

[0152] (hetero)arylcycloalkynyl groups, (hetero)alkylene groups, (hetero)alkenylene groups, (hetero)alkynylene groups, (hetero)cycloalkylene groups,

[0153] (hetero)cycloalkenylene groups, (hetero)cycloalkynylene groups, (hetero)arylene groups, alkyl(hetero)arylene groups, (hetero)arylalkylene groups,

[0154] (hetero)arylalkenylene groups, (hetero)arylalkynylene groups,

[0155] alkenyl(hetero)arylene, alkynyl(hetero)arylene, (hetero)arenetriyl groups, (hetero)cycloalkanetriyl groups, (hetero)cycloalkenetriyl and

[0156] (hetero)cycloalkynetriyl groups are optionally substituted with one or more substituents independently selected from the group consisting of -Cl, -F, -Br, -I, - OH, -NH2, -SO3H, -PO3H, -PO4H2, -NO2, -CF3, =O, =NR36, -SR36, C1-C24alkyl groups, C2-C24alkenyl groups, C2-C24alkynyl groups, C6-C24aryl groups, C2-C24heteroaryl groups, C3-C24cycloalkyl groups, C5-C24cycloalkenyl groups, C12-C24cycloalkynyl groups, C3-C24alkyl(hetero)aryl groups, C3-C24(hetero)arylalkyl groups, C4-C24(hetero)arylalkenyl groups, C4-C24(hetero)arylalkynyl groups, C4- C24alkenyl(hetero)aryl groups, C4-C24alkynyl(hetero)aryl groups, C4-C24alkylcycloalkyl groups, C6-C24alkylcycloalkenyl groups, C13-C24alkylcycloalkynyl groups, C4-C24cycloalkylalkyl groups, C6-C24cycloalkenylalkyl groups, C13-C24cycloalkynylalkyl groups, C5-C24alkenylcycloalkyl groups, C7-C24

[0157] alkenylcycloalkenyl groups, C14-C24alkenylcycloalkynyl groups, C5-C24

[0158] cycloalkylalkenyl groups, C7-C24cycloalkenylalkenyl groups, C14-C24

[0159] cycloalkynylalkenyl groups, C5-C24alkynylcycloalkyl groups, C7-C24 alkynylcycloalkenyl groups, C14-C24alkynylcycloalkynyl groups, C5-C24

[0160] cycloalkylalkynyl groups, C7-C24cycloalkenylalkynyl groups, C14-C24

[0161] cycloalkynylalkynyl groups, C5-C24cycloalkyl(hetero)aryl groups, C7-C24cycloalkenyl(hetero)aryl groups, C14-C24cycloalkynyl(hetero)aryl groups, C5-C24(hetero)arylcycloalkyl groups, C7-C24(hetero)arylcycloalkenyl groups, and C14-C24(hetero)arylcycloalkynyl groups. Unless stated otherwise, the substituents disclosed herein optionally contain one or more heteroatoms selected from the group consisting of O, S, NR36, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized. Preferably, these substituents optionally contain one or more heteroatoms selected from the group consisting of O, S, and NR36.

[0162] In preferred embodiments, the substituents are selected from the group consisting of -Cl, -F, -Br, -I, -OH, -NH2, -SO3H, -PO3H, -PO4H2, -NO2, -CF3, =O,

[0163] — NR36, -SR36, C1-C12alkyl groups, C2-C12alkenyl groups, C2-C12alkynyl groups, C6-C12aryl groups, C2-C12heteroaryl groups, C3-C12cycloalkyl groups, C5-C12cycloalkenyl groups, C12cycloalkynyl groups, C3-C12alkyl(hetero)aryl groups, C3- C12(hetero)arylalkyl groups, C4-C12(hetero)arylalkenyl groups, C4-C12

[0164] (hetero)arylalkynyl groups, C4-C12alkenyl(hetero)aryl groups, C4-C12

[0165] alky nyl(hetero) aryl groups, C4-C12alkylcycloalkyl groups, C6-C12

[0166] alkylcycloalkenyl groups, C13-C16alkylcycloalkynyl groups, C4-C12cycloalkylalkyl groups, C6-C12cycloalkenylalkyl groups, C13-C16cycloalkynylalkyl groups, C5-C12alkenylcycloalkyl groups, C7-C12alkenylcycloalkenyl groups, C14-C16

[0167] alkenylcycloalkynyl groups, C5-C12cycloalkylalkenyl groups, C7-C12

[0168] cycloalkenylalkenyl groups, C14-C16cycloalkynylalkenyl groups, C5-C12

[0169] alkynylcycloalkyl groups, C7-C12alkynylcycloalkenyl groups, C14-C16

[0170] alkynylcycloalkynyl groups, C5-C12cycloalkylalkynyl groups, C7-C12

[0171] cycloalkenylalkynyl groups, C14-C16cycloalkynylalkynyl groups, C5-C12

[0172] cycloalkyl(hetero)aryl groups, C7-C12cycloalkenyl(hetero)aryl groups, C14-C16cycloalkynyl(hetero)aryl groups, C5-C12(hetero)arylcycloalkyl groups, C7-C12(hetero)arylcycloalkenyl groups, and C14-C16(hetero)arylcycloalkynyl groups.

[0173] In preferred embodiments, the substituents are selected from the group consisting of -Cl, -F, -Br, -I, -OH, -NH2, -SO3H, -PO3H, -PO4H2, -NO2, -CF3, =O, — NR36, -SR36, C1-C7alkyl groups, C2-C7alkenyl groups, C2-C7alkynyl groups, C6- C7aryl groups, C2-C7heteroaryl groups, C3-C7cycloalkyl groups, C5-C7

[0174] cycloalkenyl groups, C12cycloalkynyl groups, C3-C7alkyl(hetero)aryl groups, C3- C7(hetero)arylalkyl groups, C4-C8(hetero)arylalkenyl groups, C4-C8

[0175] (hetero)arylalkynyl groups, C4-C8alkenyl (hetero)aryl groups, C4-C8

[0176] alky nyl(hetero) aryl groups, C4-C7alkylcycloalkyl groups, C6-C7alkylcycloalkenyl groups, C13-C16alkylcycloalkynyl groups, C4-C7cycloalkylalkyl groups, C6-C7cycloalkenylalkyl groups, C13-C16cycloalkynylalkyl groups, C5-C7

[0177] alkenylcycloalkyl groups, C7-C7alkenylcycloalkenyl groups, C14-C16

[0178] alkenylcycloalkynyl groups, C5-C7cycloalkylalkenyl groups, C7-C8

[0179] cycloalkenylalkenyl groups, C14-C16cycloalkynylalkenyl groups, C5-C7

[0180] alkynylcycloalkyl groups, C7-C8alkynylcycloalkenyl groups, C14-C16

[0181] alkynylcycloalkynyl groups, C5-C7cycloalkylalkynyl groups, C7-C8

[0182] cycloalkenylalkynyl groups, C14-C16cycloalkynylalkynyl groups, C5-C9

[0183] cycloalkyl(hetero)aryl groups, C7-C11cycloalkenyl(hetero)aryl groups, C14-C16cycloalkynyl(hetero)aryl groups, C5-C9(hetero)arylcycloalkyl groups, C7-C11(hetero)arylcycloalkenyl groups, and C14-C16(hetero)arylcycloalkynyl groups.

[0184] Unless stated otherwise, any group disclosed herein that is not cyclic is understood to be linear or branched. In particular, (hetero)alkyl groups,

[0185] (hetero)alkenyl groups, (hetero) alkynyl groups, (hetero)alkylene groups,

[0186] (hetero)alkenylene groups, (hetero)alkynylene groups, and the like are linear or branched, unless stated otherwise.

[0187] The general term "sugar" is herein used to indicate a monosaccharide, for example glucose (Glc), galactose (Gal), mannose (Man) and fucose (Fuc). The term "sugar derivative" is herein used to indicate a derivative of a

[0188] monosaccharide sugar, i.e. a monosaccharide sugar comprising substituents and / or functional groups. Examples of a sugar derivative include amino sugars and sugar acids, e.g. glucosamine (GlcNH2), galactosamine (GalNH2), N- acetylglucosamine (GlcNAc), N-acetylgalactosamine (GalNAc), sialic acid (Sia) which is also referred to as N-acetylneuraminic acid (NeuNAc), and N- acetylmuramic acid (MurNAc), glucuronic acid (GlcA) and iduronic acid (ldoA).

[0189] A sugar may be without further substitution, and then it is understood to be a monosaccharide. A sugar may be further substituted with at one or more of its hydroxyl groups, and then it is understood to be a disaccharide or an oligosaccharide. A disaccharide contains two monosaccharide moieties linked together. An oligosaccharide chain may be linear or branched, and may contain from 3 to 10 monosaccharide moieties.

[0190] The term "protein" is herein used in its normal scientific meaning. Herein, polypeptides comprising about 10 or more amino acids are considered proteins. A protein may comprise natural, but also unnatural amino acids. The term“protein” herein is understood to comprise antibodies and antibody fragments.

[0191] The term“peptide” is herein used in its normal scientific meaning. Herein, peptides are considered to comprise a number of amino acids in a range of from 2 to 9.

[0192] The term“peptoids” is herein used in its normal scientific meaning.

[0193] An antibody is a protein, typically generated by the immune system that is capable of recognizing and binding to a specific antigen. While antibodies or immunoglobulins derived from IgG antibodies are particularly well- suited for use in this invention, immunoglobulins from any of the classes or subclasses may be selected, e.g. IgG, IgA, IgM, IgD and IgE. Suitably, the immunoglobulin is of the class IgG including but not limited to IgG subclasses (IgGl, 2, 3 and 4) or class IgM which is able to specifically bind to a specific epitope on an antigen. Antibodies can be intact immunoglobulins derived from natural sources or from recombinant sources and can be immunoreactive portions of intact

[0194] immunoglobulins. Antibodies may exist in a variety of forms including, for example, polyclonal antibodies, monoclonal antibodies, camelized single domain antibodies, recombinant antibodies, anti-idiotype antibodies, multispecific antibodies, antibody fragments, such as, Fv, VHH, Fab, F(ab)2, Fab', Fab'-SH, F(ab')2, single chain variable fragment antibodies (scFv), tandem / bis-scFv, Fc, pFc', scFv-Fc, disulfide Fv (dsFv), bispecific antibodies (bc-scFv) such as BiTE antibodies, trispecific antibody derivatives such as tribodies, camelid antibodies, minibodies, nanobodies, resurfaced antibodies, humanized antibodies, fully human antibodies, single domain antibodies (sdAb, also known as Nanobody™), chimeric antibodies, antibody fusions, chimeric antibodies comprising at least one human constant region, dual-affinity antibodies such as dual-affinity retargeting proteins (DART™), and multimers and derivatives thereof, such as divalent or multivalent single-chain variable fragments (e.g. di-scFvs, tri-scFvs) including but not limited to minibodies, diabodies, triabodies, tribodies, tetrabodies, and the like, and multivalent antibodies. Reference is made to [Trends in

[0195] Biotechnology 2015, 33, 2, 65], [Trends Biotechnol. 2012, 30, 575-582], and

[0196] [Cane. Gen. Prot. 2013 10, 1-18], and [BioDrugs 2014, 28, 331—343], the contents of which are hereby incorporated by reference. "Antibody fragment" refers to at least a portion of the variable region of the immunoglobulin that binds to its target, i.e. the antigen-binding region. Other embodiments use antibody mimetics, such as but not limited to Affimers, Anticalins, Avimers, Alphabodies, Affibodies, DARPins, and multimers and derivatives thereof; reference is made to [Trends in Biotechnology 2015, 33, 2, 65], the contents of which is hereby incorporated by reference.“Antibody” as used herein also refers to antibodies with further functionalities, such as labelled antibodies, particularly radiolabeled antibodies, and antibody-drug conjugates. For the avoidance of doubt, in the context of this invention the term "antibody" is meant to encompass all of the antibody variations, fragments, derivatives, fusions, analogs and mimetics outlined in this paragraph, unless specified otherwise.

[0197] A linker is herein defined as a moiety that connects two or more elements of a compound. For example in a bioconjugate, a biomolecule and another moiety, e.g. a label, are covalently connected to each other via a linker.

[0198] A biomolecule is herein defined as any molecule that can be isolated from nature or any molecule composed of smaller molecular building blocks that are the constituents of macromolecular structures derived from nature, in particular nucleic acids, proteins, glycans and lipids. Examples of a biomolecule include an enzyme, a (non-catalytic) protein, a polypeptide, a peptide, an amino acid, an oligonucleotide, a monosaccharide, an oligosaccharide, a polysaccharide, a glycan, a lipid and a hormone.

[0199] As used herein, an organic molecule is defined as a molecule comprising a C-H bond. Organic compound and organic molecule are used synonymously. It will be understood that“organic molecule” as used herein includes biomolecules, such as nucleic acids (oligonucleotides, polynucleotides, DNA, RNA), peptides, proteins (in particular antibodies), carbohydrates

[0200] (monosaccharides, oligosaccharides, and polysaccharides), aptamers, hormones, toxins, steroids, cytokines, and lipids; small organic molecules as defined herein; polymers (in particular polyethylene glycol); LNA and PNA; amino acids;

[0201] peptoids; molecules comprising a radionuclide; fluorescent dyes; drugs; resins (in particular polystyrene and agarose); beads; particles (in particular

[0202] polymersomes, liposomes, and beads); gels; surfaces; organometallic compounds; cells; and combinations thereof.

[0203] As used herein, an inorganic molecule is defined as any molecule not being an organic molecule, i.e. not comprising a C-H bond. It will be understood that“inorganic molecule” as used herein includes surfaces (in particular chips, wafers, gold, metal, silica-based surfaces such as glass); particles such as beads (in particular magnetic beads, gold beads), silica-based particles, polymer-based materials, iron oxide particles; caron nanotubes; allotropes of carbon (in particular fullerenes such as Buckminsterfullerene; graphite, graphene, diamond, Lonsdaleite, Q-carbon, linearn acetylenic carbon, amorphous carbon, and carbon nanotubes); drugs (in particular cisplatin); and combinations thereof.

[0204] As used herein,“particle” is preferably defined as a microparticle or a nanoparticle.

[0205] The term "salt thereof’ means a compound formed when an acidic proton, typically a proton of an acid, is replaced by a cation, such as a metal cation or an organic cation and the like. The term "salt thereof’ also means a compound formed when an amine is protonated. Where applicable, the salt is a pharmaceutically acceptable salt, although this is not required for salts that are not intended for administration to a patient. For example, in a salt of a compound the compound may be protonated by an inorganic or organic acid to form a cation, with the conjugate base of the inorganic or organic acid as the anionic component of the salt.

[0206] The term "pharmaceutically accepted" salt means a salt that is acceptable for administration to a patient, such as a mammal (salts with counter- ions having acceptable mammalian safety for a given dosage regime). Such salts may be derived from pharmaceutically acceptable inorganic or organic bases and from pharmaceutically acceptable inorganic or organic acids.

[0207] "Pharmaceutically acceptable salt" refers to pharmaceutically acceptable salts of a compound, which salts are derived from a variety of organic and inorganic counter ions known in the art and include, for example, sodium, potassium, calcium, magnesium, ammonium, tetraalkylammonium, etc., and when the molecule contains a basic functionality, salts of organic or inorganic acids, such as hydrochloride, hydrobromide, formate, tartrate, besylate, mesylate, acetate, maleate, oxalate, etc.

[0208] In preferred embodiments, in relation to the invention“particle” is defined as a nanoparticle or a microparticle.

[0209] The logarithm of the partition-coefficient, i.e. Log P, is herein used as a measure of the hydrophobicity of a compound. Typically, the Log P is defined as

[0210] The skilled person is aware of methods to determine the partition-coefficient of compounds without undue experimentation. Alternatively, the skilled person knows that software is available to reliably estimate the Log P value, for example as a function within ChemDraw® software or online available tools.

[0211] The unified atomic mass unit or Dalton is herein abbreviated to Da.

[0212] The skilled person is aware that Dalton is a regular unit for molecular weight and that 1 Da is equivalent to 1 g / mol (grams per mole).

[0213] It will be understood that herein, the terms“moiety” and“group” are used interchangeably when referring to a part of a molecule. It will be understood that when a heteroatom is denoted as -X(R’)2-, wherein X is the heteroatom and R’ is a certain moiety, then this denotes that two moieties R’ are attached to the heteroatom.

[0214] It will be understood that when a group is denoted as, for example, -((R51)2-R52)2- or a similar notation, in which R51and R52are certain moieties, then this denotes that first, it should be written as -R51-R51-R52-R51-R51-R52- before the individual R51and R52moieties are selected, rather than first selecting moieties R51and R52and then writing out the formula.

[0215] The Inverse Electron-Demand Diels-Alder reaction (IEDDA)

[0216] The established IEDDA conjugation chemistry generally involves a pair of reactants that comprise, as one reactant (i.e. one Bio-orthogonal Reactive Group), a suitable diene, such as a derivative of tetrazine (TZ), e.g. an electron- deficient tetrazine and, as the other reactant (i.e. the other Bio-orthogonal Reactive Group), a suitable dienophile, such as a trans-cyclooctene (TCO). The

[0217] exceptionally fast reaction of (substituted) tetrazines, in particular electron- deficient tetrazines, with a TCO moiety results in an intermediate that

[0218] rearranges to a dihydropyridazine Diels- Alder adduct by eliminating N2 as the sole by-product. The initially formed 4,5-dihydropyridazine product may tautomerize to a 1,4- or a 2, 5 -dihydropyridazine product, especially in aqueous environments. Below a reaction scheme is given for a [4+2] IEDDA reaction between (3,6)-di-(2-pyridyl)-s-tetrazine diene and a trans-cyclooctene dienophile, followed by a retro Diels Alder reaction in which the product and dinitrogen is formed. Because the trans-cyclooctene derivative does not contain electron withdrawing groups as in the classical Diels Alder reaction, this type of Diels Alder reaction is distinguished from the classical one, and frequently referred to as an“inverse-electron-demand Diels Alder (IEDDA) reaction”. In the following text the sequence of both reaction steps, i.e. the initial Diels-Alder cyclo-addition (typically an inverse electron-demand Diels Alder cyclo-addition) and the subsequent retro Diels Alder reaction will be referred to in shorthand as the “inverse electron-demand Diels Alder reaction” or“inverse electron- demand Diels Alder conjugation” or“IEDDA”. The product of the reaction is then the IEDDA adduct or conjugate. This is illustrated in Scheme 1 below.

[0219]

[0220] Scheme 1: the IEDDA conjugation reaction

[0221] The two reactive species are abiotic and do not undergo fast metabolism or side reactions in vitro or in vivo. They are bio-orthogonal, e.g. they selectively react with each other in physiologic media. Thus, the compounds and the method of the invention can be used in a living organism. Moreover, the reactive groups are relatively small and can be introduced in biological samples or living organisms without significantly altering the size of biomolecules therein. References on the inverse electron demand Diels Alder reaction, and the behavior of the pair of reactive species include: [Thalhammer et al., Tetrahedron Lett., 1990, 31, 47, 6851-6854], [Wijnen et ah, J. Org. Chem., 1996, 61, 2001-2005], [Blackman et ah, J. Am. Chem. Soc., 2008, 130, 41, 13518-19], [Rossin et ah, Angew. Chem. Int.

[0222] Ed. 2010, 49, 3375], [Devaraj et ah, Angew. Chem. Int. Ed. 2009, 48, 7013],

[0223] [Devaraj et ah, Angew. Chem. Int. Ed., 2009, 48, 1-5].

[0224] The IEDDA Pyridazine Elimination Reaction

[0225] Below, the dienophile, a TCO, that may be comprised in kits of the invention may be referred to as a“Trigger” (TR). The dienophile is connected at the ally lie position to a Construct- A. Moreover, tetrazines that are used in the IEDDA pyridazine elimination reaction may be referred to as“Cleaving Agents”. For ease of reference, the term Construct-A in this invention is used to indicate an

[0226] Administration Agent or a Label, of which it is desired to have it first in a bound state, and being able to provoke release from that state. Without wishing to be bound by theory, the inventors believe that the Cleaving Agent provokes Construct-A release via a cascade mechanism within the IEDDA adduct, i.e. the dihydropyridazine. The cascade mechanism can be a simple one step reaction, or it can be comprised in multiple steps that involves one or more intermediate structures. These intermediates may be stable for some time or may immediately degrade to the thermodynamic end-product or to the next

[0227] intermediate structure. In any case, whether it be a simple or a multistep process, the result of the cascade mechanism is that the Construct-A gets released from the IEDDA adduct. Without wishing to be bound by theory, the design of the diene is such that the distribution of electrons within the IEDDA adduct is unfavorable, so that a rearrangement of these electrons must occur.

[0228] This situation initiates the cascade mechanism, and it therefore induces the release of the Construct-A. Specifically, and without wishing to be bound by theory, the inventors believe that the NH moiety comprised in the various dihydropyridazine tautomers, such as the 1,4- dihydropyridazine tautomer, of the IEDDA adduct can initiate an electron cascade reaction, a concerted or

[0229] consecutive shift of electrons over several bonds, leading to release of the

[0230] Construct-A. Occurrence of the cascade reaction in and / or Construct-A release from the Trigger is not efficient or cannot take place prior to the IEDDA reaction, as the Trigger-Construct-A conjugate itself is relatively stable as such. The cascade can only take place after the Cleaving Agent and the Trigger- Construct conjugate have reacted and have been assembled in the IEDDA adduct.

[0231] With reference to Scheme 2 below, and without wishing to be bound by theory, the inventors believe that the pyridazine elimination occurs from the 1,4- dihydropyridazine tautomer 4. Upon formation of the 4,5-dihydropyridazine 3, tautomerization affords intermediates 4 and 7, of which the 2,5- dihydropyridazine 7 cannot eliminate the Construct-A (CA). Instead it can slowly convert into aromatic 8, which also cannot eliminate CAor it can tautomerize back to intermediate 3. Upon formation of 4 the CAis eliminated near

[0232] instantaenously, affording free CA8 as an amine, and pyridazine elimination products 5 and 6. This elimination reaction has been shown to work equally well in the cleavage of carbamates, carbonates, esters and ethers from the TCO trigger [Versteegen et al., Angew. Chem. Int. Ed., 2018, 57, 10494] The Trigger in Scheme 2 is also optionally bound to a Construct-B (CB) , which in this case cannot release from the Trigger. Thereby Construct A can be seperated from Construct B by means of the IEDDA pyridazine elimination.

[0233]

[0234] Scheme 2. IEDDA pyridazine elimination mechanism.

[0235] In preferred embodiments, the dienophile trigger moiety used in the present invention comprises a trans-cyclooctene ring. Herein, this eight-membered ring moiety will be defined as a trans-cyclooctene moiety, for the sake of legibility, or abbreviated as“TCO” moiety. It will be understood that the essence resides in the possibility of the eight-membered ring to act as a dienophile and to be released from its conjugated Construct-A upon reaction.

[0236] The tetrazines of the kits of the invention and dienophiles are capable of reacting in an inverse electron-demand Diels- Alder reaction (IEDDA). IEDDA reaction of the Trigger with the Cleaving Agent leads to release of the Construct-A through an electron-cascade-based elimination, termed the “pyridazine elimination”. When a Cleaving Agent reacts with a Trigger capable of eliminating Construct-A, the combined proces of reaction and Construct-A elimination is termed the“IEDDA pyridazine elimination”.

[0237] This invention provides a Cleaving Agent that reacts with a

[0238] Construct-A-conjugated Trigger, resulting in the cleavage of the Trigger from the Construct-A. In one prominent embodiment this results in the cleavage of

[0239] Construct-A from Construct-B. In another embodiment the Trigger cleavage results in cleavage of one Construct A from another Construct A, as the

[0240] dienophile Trigger of Formula (1) can comprise two allylic positioned Constructs- A, wherein one or both can release from the Trigger upon reaction with a diene.

[0241] In another embodiment, Trigger cleavage results in the cleavage of one or more Construct-A from one or more Construct-B. Construct-B is the Construct, i.e. either Administration Agent or Label depending on the nature of Construct-A, that is bound to the dienophile, and cannot be released from the dienophile, unless it is bound to the allylic position via a spacer or self-imolative linker that also binds Construct-A . In preferred embodiments, the Trigger is used as a reversible covalent bond between two molecular species.

[0242] Scheme 3a below is a general scheme of Construct release according to a preferred embodiment of this invention, wherein the Construct being released is termed Construct-A (CA), and wherein another Construct, Construct-B (CB) is bound to the dienophile but not via the allylic position, wherein Construct-B cannot be released from the dienophile, and wherein either Construct A or B is the Administration Agent and the other is the Label.

[0243] Scheme 3a: General scheme of IEDDA pyridazine elimination reaction for the release of Construct-A from Construct-B according to a preferred embodiment of this invention

[0244] Scheme 3b below is a general scheme of Construct release according to another embodiment of this invention, wherein Construct-B (CB) is bound to the dienophile via a spacer or self-imolative linker that also binds Construct-A and, wherein when the spacer or self-immolative linker is released from the allylic position then Construct-B and Construct A are released from the Trigger and from each other.

[0245]

[0246] Scheme 3b: General scheme of IEDDA pyridazine elimination reaction for the release of Construct-A from Construct-B according to a another embodiment of this invention

[0247] Scheme 3c below is a general scheme of Construct release according to another embodiment of this invention, wherein the Trigger is linked to two allylic positioned Construct-A's, and wherein one or both Constructs-A's can be released from the Trigger, in any case resulting in cleavage of one Construct-A from the other Construct-A, and and wherein one Construct-A is the Administration Agent and the other Construct-A is the Label.

[0248]

[0249] Scheme 3c: General scheme of IEDDA pyridazine elimination reaction for the release of Construct-A from another Construct-A according to a preferred embodiment of this invention

[0250] The Construct release occurs through a powerful, abiotic, bio-orthogonal reaction of the dienenophile (Trigger) with the diene (Cleaving Agent), viz. the

[0251] aforementioned IEDDA. The bound Construct is a Construct- dienenophile conjugate. Possibly the Construct-A is linked to one or more additional

[0252] Constructs A linked via a spacer, for example a self-immolative linker. It will be understood that in Scheme 3a, 3b and 3c in the IEDDA adduct as well as in the end product after release, the indicated dienophile group and the indicated diene group are the residues of, respectively, the dienophile and diene groups after these groups have been converted in the IEDDA reaction.

[0253] The difference between CAand CBis that the bond between CBand the moiety holding CBis not broken upon reaction of the Trigger with the diene, whereas the bond between CAand the moiety holding CAis broken upon reaction of the Trigger with the diene. A person skilled in the art will understand that the moiety holding CAand CBrefers to the Trigger, or a self immolative linker LCbound to the Trigger. For the sake of clarity, when CBis bound to a LCthat is bound to the Trigger, the LCholding CBwill release from the Trigger upon reaction with the diene but the CBwill not release from the released LC. Likewise if CBis bound directly to the Trigger, CBwill not release from the Trigger upon reaction with the diene. A person skilled in the art will understand that when it is required to seperate one Label from one Administration Agent, that preferably one of the following requirements is met:

[0254] 1) one CAcomprises the Label and another CAcomprises the Adminstration Agent

[0255] 2) either Label or Adminstration Agent is CAand the other is CB

[0256] 3) Label and Adminstration Agent are both CB, provided that one CBis not part of R48and the other is bound to a LCwhich is part of R48, or provided that one CBmoiety is bound to a different LCmoiety than the other CBmoiety.

[0257] Other than is the case with e.g. medicinally active substances, where the in vitro or in vivo action is often changed with minor structural changes, the present invention first and foremost requires the right chemical reactivity combined with sufficient stability for the intended application. Thus, the possible structures extend to those of which the skilled person is familiar with that these are reactive as dienes or dienophiles.

[0258] Targeting

[0259] A "primary target" as used in the present invention, both in relation to the Administration Agent and the Cleaving Agent, relates to a target to be detected in a diagnostic and / or imaging method, and / or to be modulated, bound, or otherwise addressed by a pharmaceutically active compound, or other

[0260] therapeutic modality. The primary target can be selected from any suitable target within the human or animal body or on a pathogen or parasite. For example, a primary target can be any molecule or tissue, which is present in an organism, tissue or cell. Targets include cells components such as cell membranes and cell walls, cell surface targets, e.g. receptors, glycoproteins; structural proteins, e.g. amyloid plaques; extracellular targets such as stroma targets, tumor microenvironment targets, extracellular matrix targets such as growth factors, and proteases; intracellular targets, e.g. surfaces of Golgi bodies, surfaces of mitochondria, RNA, DNA, enzymes, components of cell signaling pathways; and / or foreign bodies, e.g. pathogens such as viruses, viral particles, bacteria, fungi, yeast or parts thereof. Examples of primary targets include compounds such as proteins of which the presence or expression level is correlated with a certain tissue or cell type or of which the expression level is up regulated or down-regulated in a certain disorder. According to a particular embodiment of the present invention, the primary target is a protein such as a (internalizing or non-internalizing) receptor. According to a preferred embodiment of the present invention, the primary target is an internalizing receptor. According to another preferred embodiment of the present invention, the primary target is a non- internalizing receptor.

[0261] In preferred embodiments the Primary Target can be a system in the body, such as blood circulation, lymphatic system, the nervous system, the digestion system, RES system, or organs such as the heart or kidney. For example, there are imaging agents that visualize blood flow, the liver, or identify the sentinel lymph node of a tumor.

[0262] Alternatively, the primary target may be a metabolic pathway, which is upregulated during a disease, e.g. infection or cancer, such as DNA synthesis, protein synthesis, membrane synthesis and carbohydrate uptake. In diseased tissues, above-mentioned markers can differ from healthy tissue and offer unique possibilities for early detection, specific diagnosis and therapy, especially targeted therapy.

[0263] Other non-limiting examples of Primary Targets include antibodies, proteins, carbohydrates, monosacharides, polysaccharides, cytokines, hormones, steroids, somatostatin receptor, monoamine oxidase, muscarinic receptors, myocardial sympatic nerve system, leukotriene receptors, e.g. on leukocytes, urokinase plasminogen activator receptor (uPAR), folate receptor, apoptosis marker, (anti- )angiogenesis marker, gastrin receptor, dopaminergic system, serotonergic system, GABAergic system, adrenergic system, cholinergic system, opoid receptors, GPIIb / IIIa receptor and other thrombus related receptors, fibrin, calcitonin receptor, tuftsin receptor, integrin receptor, fibronectin, VEGF / EGF and VEGF / EGF receptors, TAG72, CEA, CD19, CD20,CD22, CD40, CD45, CD74, CD79, CD105, CD138, CD174, CD227, CD326, CD340, MUCl, MUC16, GPNMB, PSMA, Cripto, Tenascin C, Melanocortin-1 receptor, CD44v6, G250, HLA DR, ED-A, ED-B, TMEFF2 , EphB2, EphA2, FAP, Mesothelin, GD2, CAIX, 5T4, matrix metalloproteinase (MMP), P / E / L-selectin receptor, LDL receptor, P- glycoprotein, neurotensin receptors, neuropeptide receptors, substance P receptors, NK receptor, CCK receptors, sigma receptors, interleukin receptors, herpes simplex virus tyrosine kinase, human tyrosine kinase, MSR1, FAP,

[0264] CXCR, tumor endothelial marker (TEM), cMET, IGFR, FGFR, GPA33, hCG, According to a further particular embodiment of the invention, the primary target and targeting agent are selected so as to result in the specific or increased targeting of a tissue or disease, such as cancer, an inflammation, an infection, a cardiovascular disease, e.g. thrombus, atherosclerotic lesion, hypoxic site, e.g. stroke, tumor, cardiovascular disorder, brain disorder, apoptosis, angiogenesis, an organ, and reporter gene / enzyme. This can be achieved by selecting primary targets with tissue-, cell- or disease- specific expression. For example, membrane folic acid receptors mediate intracellular accumulation of folate and its analogs, such as methotrexate. Expression is limited in normal tissues, but receptors are overexpressed in various tumor cell types.

[0265] In preferred embodiments the Primary Target equals a therapeutic target.

[0266] Preferred internalizing targets are:

[0267] Transferrin receptor, urokinase plasminogen activator receptor (uPAR), folate receptor, gastrin receptor, GPIIb / IIIa receptor, calcitonin receptor, tuftsin receptor, integrin receptor, VEGF / EGF receptors, CD19, CD20, CD22, CD25, CD30, CD33, CD40, CD45, CD56, CD70, CD74, CD79, CD105, CD123, CD138, CD163, CD174, CD184, CD227, CD269, CD326, CD340, CD352, MUCl, MUCl 6, GPNMB, PSMA, Cripto, Melanocortin-1 receptor, HLA DR, TMEFF2 , EphB2, EphA2, FAP, Mesothelin, GD2, CAIX, 5T4, matrix metalloproteinases (MMP), ADAM- 9, P / E / L-selectin receptor, LDL receptor, P-glycoprotein, neurotensin receptors, neuropeptide receptors, substance P receptors, NK receptor, CCK receptors, CXCR, tumor endothelial marker (TEM), cMET, IGFR, FGFR, GPA33, hCG, platelet- derived growth factor (PDGF), HER2, HER3, CA19, TAM, LGALS3BP, nectin-4, IFGR, cMET, PD1, PDL1, GPNMB, AGS-5, AGS-16, endosialin, ETBR, TM4SF1, BCMA, GPC2, TROP-2, AXL, HLA-DR, B7-H3, MTX3, MTX5, EFNA4, NOTCH, tissue factor (TF), PDGFR, GITR, OX40, RIG, MDA-5, NLRP1, NLRP3, AIM2, IDO, MEK, cGAS, NKG2A.

[0268] Preferred non-internalizing targets are Fibronectin ED-A, Fibronectin ED- B, VEGF, EGF , TAG72, CEA, CD20, CD25, MUCl, MUC16, Tenascin C,

[0269] CD44v6, CAIX, matrix metalloproteinase (e.g. MMP2), A33, mesothelin,

[0270] LGALS3BP, hCG, nectin-4, CD45, G250, GPA33 , GD2, PD1, PDL1, GITR, CD3, CD28, CTLA4, OX40, RIG, MDA-5, NLRP1, NLRP3, AIM2, IDO, MEK, cGAS,

[0271] NKG2A.

[0272] The person skilled in the art will understand that the preceding

[0273] classification is relative, as most targets are not completely internalizing or non- internalizing, but instead can be classified as relatively internalizing or relatively non-internalizing, as compared to other targets, such as TAG72 (non- internalizing) and HER2 (fast internalizing). The person skilled in the art will understand that internalization rate is an important factor in this classification, and that the nature of the Administration Agent or Targeting Agent TTcan affect this rate.

[0274] Compounds of Formula (1)

[0275] The invention pertains to compounds of Formula (1) as disclosed herein. It will be understood that the compounds of Formula (1) comprise an eight- membered trans-ring, preferably a trans-cyclooctene, formed by -CHR48, -C=C-, and X1-X5.

[0276]

[0277] Formula (1); R.48is selected from the group consisting of -LB, and -LA

[0278] In a preferred embodiment, R48is -LB.

[0279] In a preferred embodiment, R48is -LA.

[0280] As is clear from the definitions of -LBand -LAherein, both -LBand -LAmay comprise a moiety LC, which is an optional self-immolative linker, which may consist of multiple units arranged linearly and / or branched and may release one or more moieties that are denoted as CAmoieties, while moieties that are not released from the LCmay be denoted as CB. It will be understood that if LCcomprises more than one CAmoiety, these CAmoieties can independently be Label or Administration Agent, optionally linked to LCvia a spacer SP, since both are released due to the self-immolative character of LC. Preferably, if LCcomprises one CB, then said CBmoiety may be either Administration Agent or Label. Preferably, if LCcomprises more than one CB, then said CBmoieties are all either Administration Agent or Label. It will be understood that in such a way, one R48group may comprise both a Label and an Administration Agent, that are uncoupled after reaction of the compound of Formula (1) with a Cleaving Agent due to the self-immolative character of the linker LC.

[0281] By way of further clarification, if R48is LBand all d and e in Formula (2) are 0, the Label directly constitutes the leaving group of the release reaction, and if one of d or e in Formula (2) is 1, SL, which may be a self-immolative linker LC, constitutes the leaving group of the release reaction.

[0282] In Formula (1), R48is bound to the remainder of the compound of Formula (1) via a part of R48that is -O-, -S-, -OC(O)-, -OC(S)-, -SC(O)-, or -SC(S)-;

[0283] preferably -O-, or -OC(O)-, most preferably -OC(O)N- (i.e. a carbamate).

[0284] Preferably, the -O- or -S- is directly coupled to an aromatic moiety that is also part of R48. Preferably, the -OC(O)-, -OC(S)-, -SC(O)-, or -SC(S)- are directly coupled to a carbon, oxygen, nitrogen, or sulphur atom that is also part of R48, preferably to a secondary or tertiary amine. In a preferred embodiment, in Formula (1), R48is bound to the remainder of the compound of Formula (1) via a part of R48that is -O-R97-, -S-R97-, -OC(O)-R97-, -OC(S)-R97-, -SC(O)-R97-, or -SC(S)-R97-. In a preferred embodiment, in Formula (1), R48is bound to the remainder of the compound of Formula (1) via a part of R48that is -O-, -S-R99-, - OC(O)-, -OC(O)-R99-, -OC(S)-R99-, -SC(O)-R99-, or -SC(S)-R99-.

[0285] It will be understood, that preferably this notation indicates that in e.g. -OC(O)- R99-, the first O is attached to the eight-membered ring of Formula (1), and R99is connected to the remainder of R48. It will be understood that -O- denotes an ether, and can be an aromatic ether or an aliphatic ether. Likewise, -OC(O)- denotes an ester, that can be an aromatic ester or an aliphatic ester, preferably an aromatic ester. It will be understood that the part of R48that is -O-, -OC(O)-, or -OC(S)-, could be part of a spacer SPor SL, if present, or of the Administration Agent or the Label, if no spacer SPor SLis present.

[0286] In Formula (1), when R48is LBand does not comprise an Administration Agent, then R48being LBpreferably has a molecular weight of at most 50 kDa, and preferably of at most 5 kDa, even more preferably at most 2 kDa, even more preferably at most 1 kDa, even more preferably at most 500 Da.

[0287] In Formula (1), when R48is LAand does not comprise a Label then the compound of Formula (1) without R48preferably has a molecular weight of at most 50 kDa, and more preferably of at most 5 kDa, even more preferably at most 2 kDa, even more preferably at most 1 kDa. Preferably, when Formula (1) comprises one R48moiety that is LAand does not comprise a Label, then the compound of Formula (1) without R48being LAhas a molecular weight of at most 50 kDa, and more preferably of at most 5 kDa, even more preferably at most 2 kDa, even more preferably at most 1 kDa. Preferably, when Formula (1) comprises two R48moieties that are LAand do not comprise a Label, then the compound of Formula (1) without both R48has a molecular weight of at most 50 kDa, and more preferably of at most 5 kDa, even more preferably at most 2 kDa, even more preferably at most 1 kDa.

[0288] The compound of Formula (1) comprises at least one Label and at least one Administration Agent. Preferably, the compound of Formula (1) comprises at most one Label and at most one Administration Agent.

[0289] Preferably, when at least one R48is LB, then X1, X2, X3, and X4do not comprise the same Label as comprised in R48being LB. Preferably, when at least one R48is LA, then X1, X2, X3, and X4do not comprise an LA. In particularly favorable embodiments, one or both R48is / are in the axial position.

[0290] Preferably, if X5is -C(R47)2-, R48comprises a Label, and R48does not comprise an Administration Agent, then X - X5do not comprise the same Label as comprised in R48.

[0291] Preferably, if X5is -C(R47)2-, R48comprises an Administration Agent, and R48does not comprise a Label, then X - X5do not comprise the same

[0292] Administration Agent as comprised in R48.

[0293] Preferably, if X5is -C(R47)2-, and R48comprises at least one Administration Agent and at least one Label, then X - X5optionally comprise either the same

[0294] Administration Agent as comprised in R48or the same Label as comprised in R48.

[0295] In Formula (1), LAonly comprises both the Label and the Administration Agent when LAis R48.

[0296] In Formula (1), if LAbeing R48comprises both the Label and the

[0297] Administration Agent, then the SPlinked to said Label and said Administration Agent is a self-immolative linker, preferably with the proviso that at least one of Label and Administration Agent is CAin the definition of LCor the proviso that the Label and Administration Agent are bound to different LCmoieties within the same R48.

[0298] Preferably, in Formula (1), LBonly comprises both the Label and the

[0299] Administration Agent when LBis R48.

[0300] Preferably, in Formula (1), if LBbeing R48comprises both the Label and the Administration Agent, then the SPlinked to said Label and said

[0301] Administration Agent is a self-immolative linker, preferably with the proviso that at least one of Label and Administration Agent is CAin the definition of LCor with the proviso that the Label and Administration Agent are bound to different LCmoieties within the same R48.

[0302] Formula (2)

[0303] In Formula (1), the moiety LBsatisfies Formula (2):

[0304] Formula (2); wherein the dashed line denotes a bond to the remainder of the compound of Formula (1).

[0305] In Formula (2) each d independently is 0 or 1. In a preferred embodiment, at least one d is 1. In another preferred embodiment, both d are 1. In yet another preferred embodiment, both d are 0.

[0306] In Formula (2) e is an integer in a range of from 0 to 4, preferably e is at most 3, more preferably at most 2, most preferably e is at most 1. In a preferred embodiment, e is 1. In another preferred embodiment, e is 0.

[0307] In Formula (2), the Label is preferably as defined herein.

[0308] Preferably, -LBdoes not comprise an Administration Agent.

[0309] Preferably, Formula (2) is -SL-Label, wherein SLis a poly ethyleneglycol (PEG), more preferably SLis PEG4. Linker SL

[0310] In Formula (2), SLis a linker, which may be a self-immolative linker LCas defined herein.

[0311] Preferably, SLis defined as SPas defined herein, wherein it will be understood that when SLis attached to an R98, in some embodiments SLis a trivalent radical, and the suffix -ene in a preferred definition of SPis replaced with -triyl.

[0312] In preferred embodiments, SLbeing SPcomprises at least one moiety selected from the group consisting of a residue of R32, a moiety CM2, and a moiety Cx; all as described herein. In preferred embodiments, said CM2, Cxor a residue of R32connects the SPto a Label, LC, SP, R98, or TR.

[0313] In a preferred embodiment, SLis LC. Preferably, when SLis LC, then e is 0, one d is 0, and one d is 1. In another preferred embodiment, SLis not LCwhen SLis comprised in any one of X1-X4. In another preferred embodiment, SLis not LC. R98

[0314] In Formula (2), each R98individually is a Label or a clearance- directing group. In a preferred embodiment, R98is a Label. The Label of R98is preferably as defined herein, and may be the same Label as the one comprised in LBthat is not R98, or a different Label.

[0315] R99

[0316] R99is selected from the group consisting of -O-, -C(R36)2-, -S-, and -NR36-.

[0317] Clearance-directing group

[0318] A clearance-directing group is a moiety that directs a compound to an excretory organ, such as the kidneys or the liver. In that way, it ensures faster clearance of a compound from the blood in a subject and / or it controls which excretory organ will or will not process the compound to improve imaging procedures or non-target tissue dosimetry. In relation to the invention, it will be understood that the increased clearance rate of the Label after being separated from the Administration Agent is mainly due to this separation, and that the clearance-directing group merely further enhances the clearance rate of the Label and / or controls the clearance pathway.

[0319] In a preferred embodiment, the clearance-directing group is hexose-based. Hexose-based clearance- directing groups incorporate one or more hexoses (six carbon sugar moieties) recognized by Ashwell receptors or other receptors such as the mannose / N-acetylglucosamine receptor which are associated with

[0320] hepatocytes, endothelial cells and / or Kupffer cells of the liver or the mannose 6- phosphate receptor.

[0321] Exemplary hexoses are galactose, mannose, mannose 6-phosphate, N- acetylglucosamine, pentamannosylphosphate, and the like. Other moieties recognized by Ashwell receptors, including glucose, N-galactosamine, N- acetylgalactosamine, pentamannosyl phosphate, thioglycosides of galactose and, generally, D-galactosides and glucosides or the like may also be used in the practice of the present invention.

[0322] In a preferred embodiment, the clearance-directing group is galactose. Galactose thioglycoside conjugation is preferably accomplished following a procedure largely similar to the teachings of Lee et al., "2-Imino-2-methoxyethyl 1- 20 Thioglycosides: New Reagents for Attaching Sugars to Proteins,"

[0323] Biochemistry, (18):3956, 1976. Another useful galactose thioglycoside conjugation method is set forth in Drantz et al, "Attachment of Thioglycosides to Proteins: Enhancement of Liver Membrane Binding," Biochemistry, 15(18): 3963, 1976.

[0324] Formula (3)

[0325] In Formula (1), LAis a moiety satisfying Formula (3):

[0326]

[0327] Formula (3); wherein the dashed line denotes a bond to the remainder of the compound of Formula (1).

[0328] In Formula (3) each s independently is 0 or 1. In a preferred embodiment, at least one s is 1. In another preferred embodiment, both s are 1. In yet another preferred embodiment, both s are 0.

[0329] In Formula (3) i is an integer in a range of from 0 to 4, preferably i is at most 3, more preferably at most 2, most preferably i is at most 1. In a preferred embodiment, i is 1. In another preferred embodiment, i is 0.

[0330] In Formula (3), AAdenotes an Administration Agent that is an antibody.

[0331] In a preferred embodiment, Formula (3) is -SP-AA, wherein SPis a polyethylene glycol (PEG), more preferably SPis PEGs.

[0332] In a preferred embodiment, moiety LAhas a molecular weight of at most 500 kDa, more preferably at most 200 kDa, most preferably at most 160 kDa.

[0333] In a preferred embodiment, moiety LAhas a molecular weight of at least 0.1 kDa, more preferably at least 1 kDa, more preferably at least 10 kDa, most preferably at least 140 kDa.

[0334] In Formula (3), each SPindependently is a spacer, which optionally is a self-immolative linker LCas defined herein. It will be understood that if SPis linked to CC, then SPis preferably a trivalent radical and the suffix -ene in the definition of SLis to be replaced with the suffix -triyl. Preferably, SPis a spacer as defined herein. Preferably, when SPis LC, then i in Formula (3) is 0, one s is 0, and one s is 1.

[0335] In Formula (3) CCdenotes a Construct-C, wherein each Construct-C is independently selected from the group consisting of a Label, and an additional Administration Agent. The additional Administration Agent may be the same Administration Agent as comprised in LAnot being CC, or it may be a different Administration Agent.

[0336] In a preferred embodiment, the compound of Formula (1) comprises at most one CC. Preferably, when i in Formula (3) is at least 1, then in -SP-CC, the SPis an LC.

[0337] In preferred embodiments, SPin Formula (3) comprises at least one moiety selected from the group consisting of a residue of R32, a moiety CM2, and a moiety Cx; all as described herein. In preferred embodiments, said CM2, Cxor a residue of R32connects the SPto a Label, an Administration Agent, LC, SP, CC, or TR.

[0338] In a preferred embodiment, LAdoes not comprise a Label. In a preferred embodiment, X5does not comprise CC, LA, or LB.

[0339] Spacers SP

[0340] It will be understood that when herein, it is stated that“each individual SPis linked at all ends to the remainder of the structure” this refers to the fact that the spacer SPconnects multiple moieties within a structure, and therefore the spacer has multiple ends by defintion. The spacer SPmay be linked to each individual moiety via different or identical moieties that may be each

[0341] individually selected. Typically, these linking moieties are to be seen to be part of spacer SPitself. In case the spacer SPlinks two moieties within a structure,“all ends” should be interpreted as“both ends”. As an example, if the spacer connects a trans-cyclooctene moiety to a Construct A, then“the remainder of the molecule” refers to the trans-cylooctene moiety and Construct A, while the connecting moieties between the spacer and the trans-cyclooctene moiety and Construct A (i.e. at both ends) may be individually selected. Spacers SPmay consist of one or multiple Spacer Units SUarranged linearly and / or branched and may be connected to one or more CAor CBmoieties and / or one or more LCor TRmoieties. The Spacer may be used to connect CBto one TR(Example A) or more TR(Example B and C), but it can also be used to modulate the properties, e.g. pharmacokinetic properties, of the CB-TR-CAconjugate (Example D). Thus a Spacer does not necessarily connect two entities together, it may also be bound to only one component, e.g. the TRor LC. Alternatively, the Spacer may comprise a Spacer Unit linking CAor CBto TRand in addition may comprise another Spacer Unit that is only bound to the Spacer and serves to modulate the properties of the conjugate (Example F). The Spacer may also consist of two different types of SUconstructs, e.g. a PEG linked to a peptide, or a PEG linked to an alkylene moiety (Example E). For the sake of clarity, Example B depicts a SUthat is branched by using a multivalent branched SU. Example C depicts a SUthat is branched by using a linear SUpolymer, such as a peptide, whose side chain residues serve as conjugation groups.

[0342]

[0343] The Spacer may be bound to the Cleaving Agent in similar designs such as depicted in above examples A- F.

[0344] The Spacer Units include but are not limited to amino acids, nucleosides, nucleotides, and biopolymer fragments, such as oligo- or polypeptides, oligo- or polypeptoids, or oligo- or polylactides, or oligo- or poly-carbohydrates, varying from 2 to 200, particularly 2 to 113, preferably 2 to 50, more preferably 2 to 24 and more preferably 2 to 12 repeating units. Exemplary preferred biopolymer SUare peptides.

[0345] Yet other examples are alkyl, alkylene, alkenyl, alkenylene, alkynyl, alkynylene, cycloalkyl, cycloalkylene, cycloalkenyl, cycloalkenylene, cycloalkynyl, cycloalkynylene, aryl, arylene, alkylaryl, alkylarylene, arylalkyl, arylalkylene, arylalkenyl, arylalkenylene, arylalkynyl, arylalkynylene , polyethyleneamino, polyamine, which may be substituted or unsubstituted, linear or branched, may contain further cyclic moieties and / or heteroatoms, preferably O, N, and S, more preferably O; wherein in some embodiments these example SUcomprise at most 50 carbon atoms, more preferably at most 25 carbon atoms, more preferably at most 10 carbon atoms. In preferred embodiments the SUis independently selected from the group consisting of (CH2)r, (C3-C8carbocyclo), O-(CH2)r, arylene, (CH2)r-arylene, arylene- (CH2)r, (CH2)r-(C3-C8carbocyclo), (C3-C8carbocyclo)- (CH2)r, (C3-C8heterocyclo, (CH2)r-(C3-C8heterocyclo), (C3-C8heterocyclo)-(CH2)r, - (CH2)rC(O)NR4(CH2)r, (CH2CH2O)r, (CH2CH2O)rCH2,(CH2)rC(O)NR4(CH2CH2O)r, (CH2)rC(O)NR4(CH2CH2O)rCH2, (CH2CH2O)rC(O)NR4(CH2CH2O)r, (CH2CH2O)rC(O)NR4(CH2CH2O)rCH2, (CH2CH2O)rC(O)NR4CH2, -(CH2)rC(O)NR37(CH2)r, (CH2CH2O)r, (CH2CH2O)rCH2,(CH2)rC(O)NR37(CH2CH2O)r,

[0346] (CH2)rC(O)NR37(CH2CH2O)rCH2, (CH2CH2O)rC(O)NR37(CH2CH2O)r, (CH2CH2O)rC(O)NR37(CH2CH2O)rCH2, (CH2CH2O)rC(O)NR37CH2; wherein r is independently an integer from 1 -10, R4is as defined herein, and R37is as defined herein.

[0347] Other examples of Spacer Units SUare linear or branched polyalkylene glycols such as polyethylene glycol (PEG) or polypropylene glycol (PPG) chains varying from 2 to 200, particularly 2 to 113, preferably 2 to 50, more preferably 2 to 24 and more preferably 2 to 12 repeating units. It is preferred that when polyalkylene glycols such as PEG and PPG polymers are only bound via one end of the polymer chain, that the other end is terminated with -OCH3, -OCH2CH3, - OCH2CH2CO2H.

[0348] Other polymeric Spacer Units are polymers and copolymers such as poly- (2-oxazoline), poly( N-(2-hydroxypropyl)methacrylamide) (HPMA), polylactic acid (PLA), polylactic-glycolic acid (PLGA), polyglutamic acid (PG), dextran, polyvinylpyrrolidone (PVP), poly(l-hydroxymethylethylene hydroxymethyl- formal (PHF). Other exemplary polymers are polysaccharides,

[0349] glycopolysaccharides, glycolipids, polyglycoside, polyacetals, polyketals, polyamides, polyethers, polyesters. Examples of naturally occurring

[0350] polysaccharides that can be used as SUare cellulose, amylose, dextran, dextrin, levan, fucoidan, carraginan, inulin, pectin, amylopectin, glycogen, lixenan, agarose, hyaluronan, chondroitinsulfate, dermatansulfate, keratansulfate, alginic acid and heparin. In yet other exemplary embodiments, the polymeric SUcomprises a copolymer of a polyacetal / polyketal and a hydrophilic polymer selected from the group consisting of polyacrylates, polyvinyl polymers, polyesters, polyorthoesters, polyamides, oligopeptides, polypeptides and derivatives thereof. Exemplary preferred polymeric SUare PEG, HPMA, PLA, PLGA, PVP, PHF, dextran, oligopeptides, and polypeptides.

[0351] In some aspects of the invention polymers used in a SUhave a molecular weight ranging from 2 to 200 kDa, from 2 to 100 kDa, from 2 to 80 kDa, from 2 to 60 kDa, from 2 to 40 kDa, from 2 to 20 kDa, from 3 to 15 kDa, from 5 to 10 kDa, from 500 dalton to 5 kDa.

[0352] Other exemplary SUare dendrimers, such as poly(propylene imine) (PPI) dendrimers, PAMAM dendrimers, and glycol based dendrimers.

[0353] The SUof the invention expressly include but are not limited to conjugates prepared with commercially available cross-linker reagents such as BMPEO, BMPS, EMCS, GMBS, HBVS, LC-SMCC, MBS, MPBH, SBAP, SIA, SIAB,

[0354] SMCC, SMPB, SMPH, sulfo-EMCS, sulfo-GMBS, sulfo-KMUS, sulfo-MBS, sulfo- SIAB, sulfo-SMCC, sulfo-SMPB, and SVSB, DTME, BMB, BMDB, BMH, BMOE, BM(PEO)3and BM(PEO)4.

[0355] To construct a branching Spacer one may use a SUbased on one or several natural or non-natural amino acids, amino alcohol, aminoaldehyde, or polyamine residues or combinations thereof that collectively provide the required

[0356] functionality for branching. For example serine has three functional groups, i.e. acid, amino and hydroxyl groups and may be viewed as a combined amino acid an aminoalcohol residue for purpose of acting as a branching SU. Other exemplary amino acids are lysine and tyrosine. In preferred embodiments, the Spacer consist of one Spacer Unit, therefore in those cases SPequals SU. In preferred embodiments the Spacer consist of two, three or four Spacer Units.

[0357] In some aspects of the invention SPhas a molecular weight ranging from 2 to 200 kDa, from 2 to 100 kDa, from 2 to 80 kDa, from 2 to 60 kDa, from 2 to 40 kDa, from 2 to 20 kDa, from 3 to 15 kDa, from 5 to 10 kDa, from 500 dalton to 5 kDa. In some aspects of the invention, the SPhas a mass of no more than 5000 daltons, no more than 4000 daltons, no more than 3000 daltons, no more than 2000 daltons, no more than 1000 daltons, no more than 800 daltons, no more than 500 daltons, no more than 300 daltons, no more than 200 daltons. In some aspects the SPhas a mass from 100 daltons, from 200 daltons, from 300 daltons to 5000 daltons. In some aspects of the SPhas a mass from 30, 50, or 100 daltons to 1000 daltons, from about 30, 50, or 100 daltons to 500 daltons.

[0358] Preferably, each SPis independently selected from the group consisting of R97, -O-, -OC(O)-, -OC(O)-R99-, -OC(S)-R99-, -OR97-, -OC(O)-R97-, -OC(O)-R99-R97-, -OC(S)-R99-R97-, and LC. In another preferred embodiment, SPis not LCwhen SPis comprised in any one of X1-X4. In a preferred embodiment, SPis not LC.

[0359] In preferred embodiments, SPcomprises a residue of R32, a moiety CM2or a moiety Cx; all as described herein. In preferred embodiments, said CM2, Cxor a residue of R32connects the SPto a Label, an Administration Agent, LC, SP, CC, R98, or TR. R97

[0360] In a preferred embodiment, each R97is independently selected from the group consisting of C1-C24alkylene groups, C2-C24alkenylene groups, C2-C24alkynylene groups, C6-C24arylene, C2-C24heteroarylene, C3-C24cycloalkylene groups, C5-C24cycloalkenylene groups, and C12-C24cycloalkynylene groups, which are optionally further substituted with one or more substituents selected from the group consisting of -Cl, -F, -Br, -I, -OH, -NH2, -SO3H, -PO3H, -PO4H2, -NO2, - CF3, =O,— NR36, -SR36, C1-C24alkyl groups, C2-C24alkenyl groups, C2-C24alkynyl groups, C6-C24aryl groups, C2-C24heteroaryl groups, C3-C24cycloalkyl groups, C5- C24cycloalkenyl groups, C12-C24cycloalkynyl groups, C3-C24alkyl(hetero)aryl groups, C3-C24(hetero)arylalkyl groups, C4-C24(hetero)arylalkenyl groups, C4-C24(hetero)arylalkynyl groups, C4-C24alkenyl(hetero)aryl groups, C4-C24

[0361] alky nyl(hetero) aryl groups, C4-C24alkylcycloalkyl groups, C6-C24

[0362] alkylcycloalkenyl groups, C13-C24alkylcycloalkynyl groups, C4-C24cycloalkylalkyl groups, C6-C24cycloalkenylalkyl groups, C13-C24cycloalkynylalkyl groups, C5-C24alkenylcycloalkyl groups, C7-C24alkenylcycloalkenyl groups, C14-C24

[0363] alkenylcycloalkynyl groups, C5-C24cycloalkylalkenyl groups, C7-C24

[0364] cycloalkenylalkenyl groups, C14-C24cycloalkynylalkenyl groups, C5-C24

[0365] alkynylcycloalkyl groups, C7-C24alkynylcycloalkenyl groups, C14-C24

[0366] alkynylcycloalkynyl groups, C5-C24cycloalkylalkynyl groups, C7-C24

[0367] cycloalkenylalkynyl groups, C14-C24cycloalkynylalkynyl groups, C5-C24

[0368] cycloalkyl(hetero)aryl groups, C7-C24cycloalkenyl(hetero)aryl groupsC,14-C24cycloalkynyl(hetero)aryl groups, C5-C24(hetero)arylcycloalkyl groups, C7-C24(hetero)arylcycloalkenyl groups, and C14-C24(hetero)arylcycloalkynyl groups, wherein the substituents optionally contain one or more heteroatoms selected from the group consisting of O, S, NR36, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized;

[0369] and wherein preferably the alkylene groups, alkenylene groups, alkynylene groups, cycloalkylene groups, cycloalkenylene groups, and cycloalkynylene groups optionally contain one or more heteroatoms selected from the group consisting of O, S, NR36, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized.

[0370] In a preferred embodiment, each R97is independently selected from the group consisting ofC1-C12alkylene groups, C2-C12alkenylene groups, C2-C12alkynylene groups, C6-C12arylene, C2-C12heteroarylene, C3-C12cycloalkylene groups, C5-C12cycloalkenylene groups, and C12cycloalkynylene groups;

[0371] and wherein preferably the alkylene groups, alkenylene groups, alkynylene groups, cycloalkylene groups, cycloalkenylene groups, and cycloalkynylene groups optionally contain one or more heteroatoms selected from the group consisting of O, S, NR36, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized.

[0372] In a preferred embodiment, each R97is independently selected from the group consisting of C1-C6alkylene groups, C2-C6alkenylene groups, C2-C6alkynylene groups, C6-C6arylene, C2-C6heteroarylene, C3-C6cycloalkylene groups, and C5-C6cycloalkenylene groups;

[0373] and wherein preferably the alkylene groups, alkenylene groups, alkynylene groups, cycloalkylene groups, cycloalkenylene groups, and cycloalkynylene groups optionally contain one or more heteroatoms selected from the group consisting of O, S, NR36, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized.

[0374] In a preferred embodiment, the R97groups are optionally further substituted with one or more substituents selected from the group consisting of - Cl, -F, -Br, -I, -OH, -NH2, -SO3H, -PO3H, -PO4H2, -NO2, -CF3, =O, =NR36, -SR36, C1-C12alkyl groups, C2-C12alkenyl groups, C2-C12alkynyl groups, C6-C12aryl groups, C2-C12heteroaryl groups, C3-C12cycloalkyl groups, C5-C12cycloalkenyl groups, C12cycloalkynyl groups, C3-C12alkyl(hetero)aryl groups, C3-C12

[0375] (hetero)arylalkyl groups, C4-C12(hetero)arylalkenyl groups, C4-C12

[0376] (hetero)arylalkynyl groups, C4-C12alkenyl(hetero)aryl groups, C4-C12

[0377] alky nyl(hetero) aryl groups, C4-C12alkylcycloalkyl groups, C6-C12

[0378] alkylcycloalkenyl groupsC,13-C18 alkylcycloalkynyl groups, C4-C12cycloalkylalkyl groups, C6-C12cycloalkenylalkyl groups, C13-C18cycloalkynylalkyl groups, C5-C12alkenylcycloalkyl groups, C7-C12alkenylcycloalkenyl groups, C14-C16

[0379] alkenylcycloalkynyl groups, C5-C12cycloalkylalkenyl groups, C7-C12

[0380] cycloalkenylalkenyl groups, C14-C16cycloalkynylalkenyl groups, C5-C12

[0381] alkynylcycloalkyl groups, C7-C12alkynylcycloalkenyl groups, C14-C16

[0382] alkynylcycloalkynyl groups, C5-C12cycloalkylalkynyl groups, C7-C12

[0383] cycloalkenylalkynyl groups, C14-C16cycloalkynylalkynyl groups, C5-C12

[0384] cycloalkyl(hetero)aryl groups, C7-C12cycloalkenyl(hetero)aryl groups, C14-C16cycloalkynyl(hetero)aryl groups, C5-C12(hetero)arylcycloalkyl groups, C7-C12(hetero)arylcycloalkenyl groups, and C14-C16(hetero)arylcycloalkynyl groups, wherein the substituents optionally contain one or more heteroatoms selected from the group consisting of O, S, NR36, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized. In preferred embodiments, the R97groups are optionally further substituted with one or more substituents selected from the group consisting of - Cl, -F, -Br, -I, -OH, -NH2, -SO3H, -PO3H, -PO4H2, -NO2, -CF3, =O, =NR36, -SR36, C1-C6alkyl groups, C2-C6alkenyl groups, C2-C6alkynyl groups, C6aryl groups, C2-C6heteroaryl groups, C3-C6cycloalkyl groups, C5-C6cycloalkenyl groups, C3- C6alkyl(hetero)aryl groups, C3-C6(hetero)arylalkyl groups, C4-C6

[0385] (hetero)arylalkenyl groups, C4-C6(hetero)arylalkynyl groups, C4-C6

[0386] alkenyl(hetero)aryl groups, C4-C6alkynyl(hetero)aryl groups, C4-C6

[0387] alkylcycloalkyl groups, C f ; alkylcycloalkenyl groups, C4-C6cycloalkylalkyl groups, C6cycloalkenylalkyl groups, C5-C6alkenylcycloalkyl groups, C7

[0388] alkenylcycloalkenyl groups, C5-C6cycloalkylalkenyl groups, C7

[0389] cycloalkenylalkenyl groups, C5-C6alkynylcycloalkyl groups, C7

[0390] alkynylcycloalkenyl groups, C5-C6cycloalkylalkynyl groups, C5-C6

[0391] cycloalkyl(hetero)aryl groups, and C5-C6(hetero)arylcycloalkyl groups, wherein the substituents optionally contain one or more heteroatoms selected from the group consisting of O, S, NR36, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized.

[0392] In preferred embodiments, the R97groups are optionally further

[0393] substituted with one or more substituents selected from the group consisting of - Cl, -F, -Br, -I, -OH, -NH2, -SO3H, -PO3H, -PO4H2, -NO2, -CF3, =O, =NR36, -SR36, C1-C6alkyl groups, C2-C6alkenyl groups, C2-C6alkynyl groups, C6aryl groups, C2-C6heteroaryl groups, C3-C6cycloalkyl groups, C5-C6cycloalkenyl groups, C3- C7alkyl(hetero)aryl groups, C3-C7(hetero)arylalkyl groups, C4-C8

[0394] (hetero)arylalkenyl groups, C4-C8(hetero)arylalkynyl groups, C4-C8

[0395] alkenyl(hetero)aryl groups, C4-C8alkynyl(hetero)aryl groups, C4-C6

[0396] alkylcycloalkyl groups, C6-C7alkylcycloalkenyl groups, C4-C6cycloalkylalkyl groups, C6-C7cycloalkenylalkyl groups, C5-C6alkenylcycloalkyl groups, C7-C8alkenylcycloalkenyl groups, C5-C6cycloalkylalkenyl groups, C7-C8

[0397] cycloalkenylalkenyl groups, C5-C6alkynylcycloalkyl groups, C7-C8

[0398] alkynylcycloalkenyl groups, C5-C6cycloalkylalkynyl groups, C5-C9

[0399] cycloalkyl(hetero)aryl groups, and C5-C9(hetero)arylcycloalkyl groups, wherein the substituents optionally contain one or more heteroatoms selected from the group consisting of O, S, NR36, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized.

[0400] In a preferred embodiment, the R97groups are not substituted. In a preferred embodiment, the R97groups do not contain a heteroatom.

[0401] Linker LC

[0402] LCis an optional self-immolative linker, which may consist of multiple units arranged linearly and / or branched and may release one or more CAmoieties.

[0403] It will be understood that if LCcomprises more than one CAmoiety, these CAmoieties can independently be Label or Administration Agent, optionally linked to LCvia a spacer SP, since both are released due to the self- immolative character of LC. Preferably, if LCcomprises more than one CB, then said CBmoieties are all either Administration Agent or Label.

[0404] By way of further clarification, if R48is LBand all d and e in Formula (2) are 0, the Label directly constitutes the leaving group of the release reaction, and if one of d or e in Formula (2) is 1, SL, which may be a self-immolative linker LC, constitutes the leaving group of the release reaction. The possible LCstructures, their use, position and ways of attachment of linkers LC, constructs CAand CB, and the TRare known to the skilled person, see for example [Papot et al., Anticancer Agents Med. Chem., 2008, 8, 618-637]. Nevertheless, typical but non- limiting examples of self-immolative linkers LCare benzyl-derivatives, such as those drawn below. There are two main self-immolation mechanisms: electron cascade elimination and cyclization-mediated elimination. The preferred example below on the left functions by means of the cascade mechanism, wherein the bond to the YCbetween Trigger and LC, here termed YC1, is cleaved, and an electron pair of YC1, for example an electron pair of NR6, shifts into the benzyl moiety resulting in an electron cascade and the formation of 4-hydroxybenzyl alcohol, CO2and the liberated CAalso comprising an Yc, here termed YC2. The preferred example in the middle functions by means of the cyclization mechanism, wherein cleavage of the bond to the amine of YC1leads to nucleophilic attack of the amine on the carbonyl, forming a 5-ring l,3-dimethylimidazolidin-2-one and liberating the CAincluding YC2. The preferred example on the right combines both mechanisms, this linker will degrade not only into CO2and one unit of 4- hydroxybenzyl alcohol (when YC1is O), but also into one 1,3- dimethylimidazoli din-2 -one unit.

[0405]

[0406] Herein, CAis optionally linked to the remainder of LCvia a spacer SP.

[0407] By substituting the benzyl groups of aforementioned self-immolative linkers LC, it is possible to tune the rate of release of the construct CA, caused by either steric and / or electronic effects on the cyclization and / or cascade release. Synthetic procedures to prepare such substituted benzyl- derivatives are known to the skilled person (see for example [Greenwald et al, J. Med. Chem., 1999, 42, 3657-

[0408] 3667] and [Thornthwaite et al, Polym. Chem., 2011, 2, 773-790]. Preferred substituted benzyl- derivatives with different release rates are drawn below.

[0409]

[0410] Herein, CAis optionally linked to the remainder of LCvia a spacer SP.

[0411] In preferred embodiments the LCsatisfies one of the following Formulae 23a-c

[0412] Formula 23a Formula 23b Formula 23c wherein YC1is O, S or NR6; V, U, W, Z are each independently CR7or N; YC2is O, S, secondary amine or tertiary amine, wherein these YC2moieties are part of CA; with R6, R7, R8, R9as defined herein, and wherein, CAis optionally linked to the remainder of LCvia a spacer SP.

[0413] In preferred embodiments it is preferred that R6is H or methyl, R7is H, R8is H or methyl and R9is H. In preferred embodiments the R7comprised in Formula 23c is CF3and Z is N. In preferred embodiments the LCsatisfies the following Formula 23d

[0414]

[0415] Formula 23d wherein YC1is O, S or NR6; YC2is O, S, secondary amine or tertiary amine, wherein these YC2moieties are part of CA; with R6, R7, R8, R9as defined herein; preferably R7is C1-C8alkyl, C6-C12aryl, C1-C8O-alkyl, C6-C12O-aryl , NO2, F, Cl, Br, I, CN, with m being an integer from 0 to 4; preferably each R8and R9are independently H, C1-C8alkyl, C6-C12 aryl, C1-C8O-alkyl, C6-C12O-aryl , NO2, F, Cl, Br, I, CN; and wherein, CAis optionally linked to the remainder of LCvia a spacer SP. Preferably R7is electron donating and preferably m is an integer between 0 and 2, more preferably m is 0. Preferably R8is H and R9is H or methyl.

[0416] Self-immolative linkers that undergo cyclization include but are not limited to substituted and unsubstituted aminobutyric acid amide, appropriately

[0417] substituted bicyclo[2.2.1] and bicyclo[2.2.2] ring system, 2-aminophenylpropionic acid amides, and trimethyl lock-based linkers, see e.g. [Chem. Biol. 1995, 2, 223], [J. Am. Chem. Soc. 1972, 94, 5815], [J. Org. Chem. 1990, 55, 5867], the contents of which are hereby incorporated by reference. Preferably, with an LCthat releases CAby means of cyclization, the remainder of CAis bound to LCvia YC1 being an aromatic oxygen of sulfur. It will be understood that e.g. aromatic oxygen means an oxygen that is directly attached to an aromatic group.

[0418] In preferred embodiments such cyclization LCsatisfies one of the following Formulae 24a-f.

[0419]

[0420] Formula 24a Formula 24b Formula 24c Formula 24d

[0421]

[0422] Formula 24f

[0423] Wherein YC1is NR6; YC2is O or S, wherein these YC2moieties are part of CA; a is independently 0 or 1; R6and R7are as defined herein, and wherein, CAis optionally linked to the remainder of LCvia a spacer SP. Preferably R6and R7are H, unsubstituted C1-C8alkyl, C6aryl, more preferably R6is H or methyl and R7is

[0424] H.

[0425] In a preferred embodiment, the remainder of CAin Formula 24a,

[0426] 24b, 24c, 24d and 24e is bound to YC2via an aromatic moiety, said moiety being a part of CA. In a preferred embodiment, the remainder of CAin Formula 24f is bound to YC2via an aliphatic moiety, said moiety being a part of CA.

[0427] Several preferred structures of LCare shown below. In these examples CAis preferably bound to LCvia an YC2that is O or S, wherein O or S is part of CA. For the avoidance of doubt, in these examples YC1is not denoted as such but is embodied by the relevant NH, NR6, S, O groups.

[0428]

[0429] Herein, CAis optionally linked to the remainder of LCvia a spacer SP; and R6is as defined herein

[0430] Several other preferred structures of LCare shown below. In these examples CAis preferably bound to LCvia an YC2that is a secondary or primary amine, and wherein said YC2is part of CA. For the avoidance of doubt, in these examples YC1is not denoted as such but is embodied by the relevant NH, NR6, S, O groups, and CAis optionally linked to the remainder of LCvia a spacer SP.

[0431]

[0432] Herein, R6is as defined herein.

[0433] Further preferred structures of LCcan be found in

[0434] WO2009017394(A1), US7375078, WO2015038426A1, WO2004043493, Angew.

[0435] Chem. Int. Ed. 2015, 54, 7492— 7509, the contents of which are hereby incorporated by reference.

[0436] In preferred embodiments of the invention the LChas a mass of no more than 1000 daltons, no more than 500 daltons, no more than 400 daltons, no more than 300 daltons, or from 10, 50 or 100 to 1000 daltons, from 10, 50, 100 to 400 daltons, from 10, 50, 100 to 300 daltons, from 10, 50, 100 to 200 daltons, e.g., 10-1000 daltons, such as 50-500 daltons, such as 100 to 400 daltons.

[0437] A person skilled in the art will know that one LCmay be connected to another LCthat is bound to CA, wherein upon reaction of the Cleaving Agent with the Trigger TR, LC-LC-CAis released from the TR, leading to self-immolative release of both LCmoieties and the CAmoiety. With respect to the LCformulas disclosed herein, the LClinking the TRto the other LCthen does not release CAbut an LCthat is bound via YC1and further links to a CA.

[0438] R6, R7, R8, R9are as defined herein.

[0439] In a preferred embodiment, LCis selected from the group consisting of linkers according to Group I, Group II, and Group III,

[0440] wherein linkers according to Group I are

[0441]

[0442] , wherein U, V, W, Z are each independently selected from the group consisting of -CR7-, and -N-. Herein, e is either 0 or 1, and X is selected from the group consisting of -O-, -S- and -NR6-. Preferably, each R8and R9are independently selected from the group consisting of hydrogen, C1-C4alkyl groups, C2-C4alkenyl groups, and C4-6(hetero)aryl groups, wherein for R8and R9the alkyl groups, alkenyl groups, and (hetero)aryl groups are optionally substituted with a moiety selected from the group consisting of -Cl, -F, -Br, -I, -OH, -NH2, =O, -SH, -SO3H, - PO3H, -PO4H2and -NO2and optionally contain at most two heteroatoms selected from the group consisting of -O-, -S-, -NH-, -P-, and -Si-, wherein the N, S, and P atoms are optionally oxidized. For linkers according to Group I CAis linked to LCvia a moiety selected from the group consisting of -O-, -N-, -C-, and -S-, preferably from the group consisting of secondary amines and tertiary amines, wherein said moieties are part of CA.

[0443] The linker according to Group II is

[0444]

[0445] , wherein m is an integer between 0 and 2, preferably m is 0, and wherein e is either 0 or 1. For linkers according to Group II CAis linked to LCvia a moiety selected from the group consisting of -O-, -N-, -C-, and -S-, preferably from the group consisting of secondary amines and tertiary amines, wherein said moieties are part of CA.

[0446] Linkers according to Group III are

[0447]

[0448] wherein for linkers according to Group III CAis linked to LCvia a moiety selected from the group consisting of -O- and -S-, preferably -O- or -S- bound to a C4-6 (hetero)aryl group, wherein said moieties are part of CA.

[0449] For linkers according to Groups I-III preferably each R6is independently selected from the group consisting of hydrogen, C1-C4alkyl groups, C2-C4alkenyl groups, and C4-6(hetero)aryl groups, wherein for R6the alkyl groups, alkenyl groups, and (hetero)aryl groups are optionally substituted with a moiety selected from the group consisting of -Cl, -F, -Br, -I, -OH, -NH2, =O, -SH, -SO3H, -PO3H,- PO4H2and -NO2and optionally contain at most two heteroatoms selected from the group consisting of -O-, -S-, -NH-, -P-, and -Si-, wherein the N, S, and P atoms are optionally oxidized. For linkers of Groups I-III preferably each R7is independently selected from the group consisting of hydrogen and C1-C3alkyl groups, C2-C3alkenyl groups, and C4-6 (hetero)aryl groups, wherein for R7the alkyl groups, alkenyl groups, and (hetero)aryl groups are optionally substituted with a moiety selected from the group consisting of -Cl, -F, -Br, -I, -OH, -NH2, =O, =NH, -N(CH3)2, - S(O)2CH3, and -SH, and are optionally interrupted by at most one heteroatom selected from the group consisting of -O-, -S-, -NH-, -P-, and -Si-, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized, wherein R7is preferably selected from the group consisting of hydrogen, methyl, -CH2-CH2-N(CH3)2, and -CH2-CH2-S(O)2-CH3.

[0450] R6, R7, R8, R9comprised in said Group I, II and III, can optionally also be -

[0451] (SP)i-CB.

[0452] For all linkers according to Group I and Group II YC1is selected from the group consisting of -O-, -S-, and -NR6-, preferably -NR6-. For all linkers according to Group III, YC1is -NR6-. For all linkers according to Group I, Group II, and Group III, YC2is selected from the group consisting of O and S, preferably O.

[0453] Preferably, in Groups I-III when two LCare linked to each other, then the LCattached to the -O- or -S- at the allylic position of the trans-cyclooctene is selected from the group consisting of linkers according to Group I and Group II, and the LCbetween the LCattached to the -O- or -S- at the allylic position of the trans-cyclooctene and CAis selected from Group III, and that the wiggly line in the structures of Group III then denotes a bond to the LCattached to the -O- or -S- at the allylic position of the trans-cyclooctene instead of a bond to the allylic -O- or -S- on the trans-cyclooctene ring, and that the double dashed line in the structures of Groups I and II then denotes a bond to the LCbetween the LCattached to the -O- or -S- at the allylic position of the trans-cyclooctene and the CAinstead of a bond to CA.

[0454] In preferred embodiments, LCis selected from the group consisting of linkers according to Group IV, Group V, Group VI, and Group VII.

[0455] Linkers according to Group IV are

[0456]

[0457] , wherein CAis linked to LCvia a moiety selected from the group consisting of -O- and -S-, preferably from the group consisting of -O-C5-8-arylene- and -S-C5-8- arylene-, wherein said moieties are part of CA.

[0458] Linkers according to Group V are

[0459]

[0460] , wherein CAis linked to LCvia a moiety selected from the group consisting of -O- and -S-, wherein said moieties are part of CA.

[0461] Linkers according to Group VI are

[0462]

[0463] , wherein CAis linked to LCvia a moiety selected from the group consisting of -O-, -N-, and -S-, preferably a secondary or a tertiary amine, wherein said moieties are part of CA.

[0464] Linkers according to Group VII are

[0465]

[0466] , wherein CAis linked to LCvia a moiety selected from the group consisting of -O-, -N-, and -S-, preferably from the group consisting of secondary amines and tertiary amines, wherein said moieties are part of CA, wherein when multiple double dashed lines are shown within one LC, each CAmoiety is independently selected.

[0467] For all linkers according to Group IV, Group V, Group VI, and Group VII, YC1is selected from the group consisting of -O-, -S-, and -NR6-. For all linkers according to Groups IV- VII R6and R7are as defined herein; i is an integer in a range of from 0 to 4, preferably 0 or 1; and j is 0 or 1.

[0468] In preferred embodiments, R6, R7, R8and R9in LCformulas, in particular in any one of Groups I- VII, are hydrogen.

[0469] Preferably, each R6is independently selected from the group consisting of hydrogen, -(SP)i-CC, C1-C24alkyl groups, C2-C24alkenyl groups, C2-C24alkynyl groups, C6-C24aryl groups, C2-C24heteroaryl groups, C3-C24cycloalkyl groups, C5- C24cycloalkenyl groups, C12-C24cycloalkynyl groups, C3-C24

[0470] (cyclo)alkyl(hetero)aryl groups, C3-C24(hetero)aryl(cyclo)alkyl, C4-C24

[0471] (cyclo)alkenyl(hetero)aryl groups, C4-C24(hetero)aryl(cyclo)alkenyl groups, C4-C24(cyclo)alkynyl(hetero)aryl groups, C4-C24(hetero)aryl(cyclo) alkynyl groups, C4-C24 alkylcycloalkyl groups, and C4-C24cycloalkylalkyl groups; wherein i is an integer in a range of from 0 to 4, preferably i is 1;

[0472] the R6groups not being hydrogen are optionally substituted with a moiety selected from the group consisting of -Cl, -F, -Br, -I, -OH, -NH2, -SO3H, -PO3H,- PO4H2,-NO2, -CF3, =O, =NH, and -SH, and optionally contain one or more heteroatoms selected from the group consisting of O, S, NH, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized.

[0473] In preferred embodiments, each R6is individually selected from the group consisting of hydrogen, C1-C8alkyl groups, C2-C8alkenyl groups, C2-C8alkynyl groups, C6-C12aryl, C2-C12heteroaryl, C3-C8cycloalkyl groups, C5-C8cycloalkenyl groups, C3-C12alkyl(hetero)aryl groups, C3-C12(hetero)arylalkyl groups, C4-C12alkylcycloalkyl groups, C4-C12cycloalkylalkyl groups, C5-C12

[0474] cycloalkyl(hetero)aryl groups and C5-C12(hetero)arylcycloalkyl groups, wherein the R6groups not being hydrogen are optionally substituted with a moiety selected from the group consisting of -Cl, -F, -Br, -I, -OH, -NH2, -SO3H, -PO3H,- PO4H2,-NO2, -CF3, =O, =NH, and -SH, and optionally contain one or more heteroatoms selected from the group consisting of O, S, NH, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized.

[0475] In preferred embodiments, R6is selected from the group consisting of hydrogen, C1-C4alkyl groups, C2-C4alkenyl groups, C2-C4alkynyl groups, C6-C8aryl, C2-C8heteroaryl, C3-C6cycloalkyl groups, C5-C6cycloalkenyl groups, C3-C10alkyl(hetero)aryl groups, C3-C10(hetero)arylalkyl groups, C4-C8alkylcycloalkyl groups, C4-C8cycloalkylalkyl groups, C5-C10cycloalkyl(hetero)aryl groups and C5- C10(hetero)arylcycloalkyl groups, wherein the R6groups not being hydrogen are optionally substituted with a moiety selected from the group consisting of -Cl, -F, -Br, -I, -OH, -NH2, -SO3H, -PO3H, -PO4H2,-NO2, -CF3, =O, =NH, and -SH, and optionally contain one or more heteroatoms selected from the group consisting of O, S, NH, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized.

[0476] In preferred embodiments, R6is selected from the group consisting of hydrogen, C1-C4alkyl groups, C2-C4alkenyl groups, and C4-6(hetero)aryl groups, wherein for R6the alkyl groups, alkenyl groups, and (hetero)aryl groups are optionally substituted with a moiety selected from the group consisting of -Cl, -F, -Br, -I, -OH, -NH2, =O, -SH, -SO3H, -PO3H, -PO4H2and -NO2and optionally contain at most two heteroatoms selected from the group consisting of -O-, -S-, - NH-, -P-, and -Si-, wherein the N, S, and P atoms are optionally oxidized.

[0477] In preferred embodiments, R6is selected from the group consisting of hydrogen,1-C3alkyl groups, C2-C3alkenyl groups, and C4-6(hetero)aryl groups, wherein for R6the alkyl groups, alkenyl groups, and (hetero)aryl groups are optionally substituted with a moiety selected from the group consisting of -Cl, -F, -Br, -I, -OH, -NH2, =O, -SH, -SO3H, -PO3H, -PO4H2and -NO2and optionally contain at most two heteroatoms selected from the group consisting of -O-, -S-, - NH-, -P-, and -Si-, wherein the N, S, and P atoms are optionally oxidized.

[0478] In preferred embodiments, the R6groups not being hydrogen are not substituted. In preferred embodiments, the R6groups not being hydrogen do not contain heteroatoms. In preferred embodiments, the R6groups are hydrogen.

[0479] RI

[0480] In preferred embodiments, each R7is independently selected from the group consisting of hydrogen, -(SP)i-CC, -F, -Cl, -Br, -I, -OR37, -N(R37)2, -SO3, -PO3, -NO2, -CF3, -SR37, S(=O)2N(R37)2, OC(=O)R37, SC(=O) R37, OC(=S)R37, SC(=S)R37,

[0481] NR37C(=O)-R37, NR37C(=S)-R37, NR37C(=O)O-R37, NR37C(=S)O-R37, NR37C(=O)S- R37, NR37C(=S)S-R37, OC(=O)N(R37)2, SC(=O)N(R37)2, OC(=S)N(R37)2,

[0482] SC(=S)N(R37)2, NR37C(=O)N(R37)2, NR37C(=S)N(R37)2, C(=O)R37,C(=S)R37,

[0483] C(=O)N(R37)2, C(=S)N(R37)2, C(=O)O-R37, C(=O)S-R37, C(=S)O-R37, C(=S)S-R37, S(O)R37, -S(O)2R37, NR37S(O)2R37, -ON(R37)2, -NR37OR37, C-1C24alkyl groups, C2- C24alkenyl groups, C2-C24alkynyl groups, C6-C24aryl groups, C2-C24heteroaryl groups, C3-C24cycloalkyl groups, C5-C24cycloalkenyl groups, C12-C24cycloalkynyl groups, C3-C24(cyclo)alkyl(hetero)aryl groups, C3-C24(hetero)aryl(cyclo) alkyl, C4- C24(cyclo)alkenyl(hetero)aryl groups, C4-C24(hetero)aryl(cyclo) alkenyl groups, C4-C24(cyclo)alkynyl(hetero)aryl groups, C4-C24(hetero)aryl(cyclo)alkynyl groups, C4-C24alkylcycloalkyl groups, and C4-C24cycloalkylalkyl groups; wherein i is an integer in a range of from 0 to 4, preferably i is 1,

[0484] wherein the alkyl groups, alkenyl groups, alkynyl groups, aryl, heteroaryl, cycloalkyl groups, cycloalkenyl groups, cycloalkynyl groups,

[0485] (cyclo)alkyl(hetero)aryl groups, (hetero)aryl(cyclo) alkyl groups,

[0486] (cyclo)alkenyl(hetero)aryl groups, (hetero)aryl(cyclo)alkenyl groups,

[0487] (cyclo)alkynyl(hetero)aryl groups, (hetero)aryl(cyclo)alkynyl groups,

[0488] alkylcycloalkyl groups, cycloalkylalkyl groups are optionally substituted with a moiety selected from the group consisting of -Cl, -F, -Br, -I, -OR37, -N(R37)2, - SO3R37, -PO3(R37)2, -PO4(R37)2, -NO2, -CF3, =O, =NR37, and -SR37, and optionally contain one or more heteroatoms selected from the group consisting of O, S, NR37, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized.

[0489] In preferred embodiments, each R7is independently selected from the group consisting hydrogen, -F, -Cl, -Br, -I, -OR37, -N(R37)2, -SO3, -PO3, -NO2, -CF3, -SR37, S(=O)2N(R37)2, OC(=O)R37, SC(=O) R37, OC(=S)R37, SC(=S)R37, NR37C(=O)- R37, NR37C(=S)-R37, NR37C(=O)O-R37, NR37C(=S)O-R37, NR37C(=O)S-R37,

[0490] NR37C(=S)S-R37, OC(=O)N(R37)2, SC(=O)N(R37)2, OC(=S)N(R37)2, SC(=S)N(R37)2, NR37C(=O)N(R37)2, NR37C(=S)N(R37)2, C(=O)R37,C(=S)R37,C(=O)N(R37)2,

[0491] C(=S)N(R37)2, C(=O)O-R37, C(=O)S-R37, C(=S)O-R37, C(=S)S-R37, S(O)R37, - S(O) 2R37, NR37S(O)2R37, -ON(R37)2, -NR37OR37, C1-C8alkyl groups, C2-C8alkenyl groups, C2-C8alkynyl groups, C6-C12aryl groups, C2-C12heteroaryl groups, C3-C8cycloalkyl groups, C5-C8cycloalkenyl groups, C3-C12alkyl(hetero)aryl groups, C3- C12(hetero)arylalkyl groups, C4-C12alkylcycloalkyl groups, C4-C12cycloalkylalkyl groups, C5-C12cycloalkyl(hetero)aryl groups and C5-C12(hetero)arylcycloalkyl groups, wherein the alkyl groups, alkenyl groups, alkynyl groups, aryl,

[0492] heteroaryl, cycloalkyl groups, cycloalkenyl groups, alkyl(hetero)aryl groups, (hetero)arylalkyl groups, alkylcycloalkyl groups, cycloalkylalkyl groups, cycloalkyl(hetero)aryl groups and (hetero)arylcycloalkyl groups are optionally substituted with a moiety selected from the group consisting of -Cl, -F, -Br, -I, - OR37, -N(R37)2, -SO3R37, -PO3(R37)2, -PO4(R37)2, -NO2, -CF3, =O, =NR37, and -SR37, and optionally contain one or more heteroatoms selected from the group

[0493] consisting of O, S, NR37, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized.

[0494] In preferred embodiments, each R7is independently selected from the group consisting of hydrogen, -F, -Cl, -Br, -I, -OR37, -N(R37)2, -SO3, -PO3·, -NO2, - CF3, -SR37, S(=O)2N(R37)2, OC(=O)R37, SC(=O) R37, OC(=S)R37, SC(=S)R37,

[0495] NR37C(=O)-R37, NR37C(=S)-R37, NR37C(=O)O-R37, NR37C(=S)O-R37, NR37C(=O)S- R37, NR37C(=S)S-R37, OC(=O)N(R37)2, SC(=O)N(R37)2, OC(=S)N(R37)2,

[0496] SC(=S)N(R37)2, NR37C(=O)N(R37)2, NR37C(=S)N(R37)2, C(=O)R37,C(=S)R37,

[0497] C(=O)N(R37)2, C(=S)N(R37)2, C(=O)O-R37, C(=O)S-R37, C(=S)O-R37, C(=S)S-R37, S(O)R37, -S(O)2R37, NR37S(O)2R37, -ON(R37)2, -NR37OR37, C-1C4alkyl groups, C2-C4alkenyl groups, C2-C4alkynyl groups, C6-C8aryl groups, C2-C8heteroaryl groups, C3-C6cycloalkyl groups, C5-C6cycloalkenyl groups, C3-C10alkyl(hetero)aryl groups, C3-C10(hetero)arylalkyl groups, C4-C10alkylcycloalkyl groups, C4-C10cycloalkylalkyl groups, C5-C10cycloalkyl(hetero)aryl groups and C5-C10

[0498] (hetero)arylcycloalkyl groups, wherein the alkyl groups, alkenyl groups, alkynyl groups, aryl, heteroaryl, cycloalkyl groups, cycloalkenyl groups, alkyl(hetero)aryl groups, (hetero)arylalkyl groups, alkylcycloalkyl groups, cycloalkylalkyl groups, cycloalkyl(hetero)aryl groups and (hetero)arylcycloalkyl groups are optionally substituted with a moiety selected from the group consisting of -Cl, -F, -Br, -I, - OR37, -N(R37)2, -SO3R37, -PO3(R37)2, -PO4(R37)2, -NO2, -CF3, =O, =NR37, and -SR37, and optionally contain one or more heteroatoms selected from the group consisting of O, S, NR37, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized.

[0499] In preferred embodiments, each R7is independently selected from the group consisting of hydrogen andC1-C3alkyl groups, C2-C3alkenyl groups, and C4-6(hetero)aryl groups, wherein the alkyl groups, alkenyl groups, and

[0500] (hetero)aryl groups are optionally substituted with a moiety selected from the group consisting of -Cl, -F, -Br, -I, -OH, -NH2, =O, =NH, -N(CH3)2, -S(O)2CH3, and -SH, and are optionally interrupted by at most one heteroatom selected from the group consisting of -O-, -S-, -NH-, -P-, and -Si-, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized.

[0501] In preferred embodiments, R7is preferably selected from the group consisting of hydrogen, methyl, -CH2-CH2-N(CH3)2, and -CH2-CH2-S(O)2-CH3. In preferred embodiments, the R7groups not being hydrogen are not substituted. In preferred embodiments, the R7groups not being hydrogen do not contain heteroatoms. In preferred embodiments, the R7groups are hydrogen.

[0502] R8and R9

[0503] R8and R9are as defined for R7. In preferred embodiments, at least one or all R8are -H. In preferred embodiments, at least one or all R8are -CH3. In preferred embodiments, at least one or all R9are -H. In preferred embodiments, at least one or all R9are -CH3. In preferred embodiments, the R8and R9groups not being hydrogen are not substituted. In preferred embodiments, the R8and R9groups not being hydrogen do not contain heteroatoms. In preferred embodiments, the R8and R9groups are hydrogen. X1, X2, X3, X4. and X5

[0504] In Formula (1), each X1, X2, X3, X4is independently selected from the group consisting of -C(R47)2-, -NR37-, -C(O)-, -O-, such that at most two of X1, X2, X3, X4are not -C(R47)2-, and with the proviso that no sets consisting of adjacent atoms are present selected from the group consisting of -O-O-, -O-N-, -C(O)-O-, N-N-, and -C(O)-C(O)-.

[0505] In a preferred embodiment, X1, X2, X3, and X4are -C(R47)2-, and preferably at most four R47, more preferably at most two R47, most preferably at most one R47, are not H. In Formula (1) X5is -C(R47)2- or -CHR48. In a preferred

[0506] embodiment, X5is -C(R47)2-; more preferably X5is -CHR47, and most preferably X5is -CH2. In a preferred embodiment X5is CHR48. R36

[0507] In a preferred embodiment, R36is as defined for R37.

[0508] In Formula (1) R36is preferably selected from the group consisting of hydrogen, C1-Ce alkyl groups, C2-C8alkenyl groups, and C4-6(hetero)aryl groups, wherein the alkyl groups, alkenyl groups, and (hetero)aryl groups are optionally

[0509] substituted with a moiety selected from the group consisting of -Cl, -F, -Br, -I, - OH, -NH2, =O, -SH, -SO3H, -PO3H, -PO4H2and -NO2and optionally contain at most two heteroatoms selected from the group consisting of -O-, -S-, -NH-, -P-, and -Si-, wherein the N, S, and P atoms are optionally oxidized. In preferred embodiments, the R36groups not being hydrogen are not substituted. In

[0510] preferred embodiments, the R36groups not being hydrogen do not contain heteroatoms. In some preferred embodiments, R36is hydrogen.

[0511] R47

[0512] In Formula (1) each R47 is independently selected from the group consisting of hydrogen, -LB, -LA, -(SP)i-CC, -F, -Cl, -Br, -I, -OR37, -N(R37)2, -SO3, -PO3-, -NO2, - CF3, -SR37, S(=O)2N(R37)2, OC(=O)R37, SC(=O) R37, OC(=S)R37, SC(=S)R37,

[0513] NR37C(=O)-R37, NR37C(=S)-R37, NR37C(=O)O-R37, NR37C(=S)O-R37, NR37C(=O)S- R37, NR37C(=S)S-R37, OC(=O)N(R37)2, SC(=O)N(R37)2, OC(=S)N(R37)2,

[0514] SC(=S)N(R37)2, NR37C(=O)N(R37)2, NR37C(=S)N(R37)2, C(=O)R37,C(=S)R37,

[0515] C(=O)N(R37)2, C(=S)N(R37)2, C(=O)O-R37, C(=O)S-R37, C(=S)O-R37, C(=S)S-R37, S(O)R37, -S(O)2R37, NR37S(O)2R37, -ON(R37)2, -NR37OR37, C-1C24alkyl groups, C2- C24alkenyl groups, C2-C24alkynyl groups, C6-C24aryl groups, C2-C24heteroaryl groups, C3-C24cycloalkyl groups, C5-C24cycloalkenyl groups, C12-C24cycloalkynyl groups, C3-C24(cyclo)alkyl(hetero)aryl groups, C3-C24(hetero)aryl(cyclo) alkyl, C4- C24(cyclo)alkenyl(hetero)aryl groups, C4-C24(hetero)aryl(cyclo) alkenyl groups, C4-C24(cyclo)alkynyl(hetero)aryl groups, C4-C24(hetero)aryl(cyclo)alkynyl groups, C4-C24alkylcycloalkyl groups, and C4-C24cycloalkylalkyl groups; wherein i is an integer in a range of from 0 to 4, preferably i is an integer ranging from 0 to 1, wherein the alkyl groups, alkenyl groups, alkynyl groups, aryl, heteroaryl, cycloalkyl groups, cycloalkenyl groups, cycloalkynyl groups,

[0516] (cyclo)alkyl(hetero)aryl groups, (hetero)aryl(cyclo) alkyl groups,

[0517] (cyclo)alkenyl(hetero)aryl groups, (hetero)aryl(cyclo)alkenyl groups,

[0518] (cyclo)alkynyl(hetero)aryl groups, (hetero)aryl(cyclo)alkynyl groups,

[0519] alkylcycloalkyl groups, cycloalkylalkyl groups are optionally substituted with a moiety selected from the group consisting of -Cl, -F, -Br, -I, -OR37, -N(R37)2, - SO3R37, -PO3(R37)2, -PO4(R37)2, -NO2, -CF3, =O, =NR37, and -SR37, and optionally contain one or more heteroatoms selected from the group consisting of O, S, NR37, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized.

[0520] In preferred embodiments, each R47is independently selected from the group consisting of hydrogen, -LB, -LA, -(SP)i-CC, -F, -Cl, -Br, -I, -OR37, -N(R37)2, - SO3, -PO3-, -NO2, -CF3, -SR37, S(=O)2N(R37)2, OC(=O)R37, SC(=O) R37, OC(=S)R37, SC(=S)R37, NR37C(=O)-R37, NR37C(=S)-R37, NR37C(=O)O-R37, NR37C(=S)O-R37, NR37C(=O)S-R37, NR37C(=S)S-R37, OC(=O)N(R37)2, SC(=O)N(R37)2, OC(=S)N(R37)2, SC(=S)N(R37)2, NR37C(=O)N(R37)2, NR37C(=S)N(R37)2, C(=O)R37,C(=S)R37,

[0521] C(=O)N(R37)2, C(=S)N(R37)2, C(=O)O-R37, C(=O)S-R37, C(=S)O-R37, C(=S)S-R37, S(O)R37, -S(O)2R37, NR37S(O)2R37, -ON(R37)2, -NR37OR37, C1-C8alkyl groups, C2-C8alkenyl groups, C2-C8alkynyl groups, C6-C12aryl groups, C2-C12heteroaryl groups, C3-C8cycloalkyl groups, C5-C8cycloalkenyl groups, C3-C12

[0522] alkyl(hetero)aryl groups, C3-C12(hetero)arylalkyl groups, C4-C12alkylcycloalkyl groups, C4-C12cycloalkylalkyl groups, C5-C12cycloalkyl(hetero)aryl groups and C5-C12(hetero)arylcycloalkyl groups, wherein the alkyl groups, alkenyl groups, alkynyl groups, aryl, heteroaryl, cycloalkyl groups, cycloalkenyl groups, alkyl(hetero)aryl groups, (hetero)arylalkyl groups, alkylcycloalkyl groups, cycloalkylalkyl groups, cycloalkyl(hetero)aryl groups and (hetero)arylcycloalkyl groups are optionally substituted with a moiety selected from the group

[0523] consisting of -Cl, -F, -Br, -I, -OR37, -N(R37)2, -SO3R37, -PO3(R37)2, -PO4(R37)2, -NO2, -CF3, =O,— NR37, and -SR37, and optionally contain one or more heteroatoms selected from the group consisting of O, S, NR37, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized.

[0524] In preferred embodiments, each R47 is independently selected from the group consisting of hydrogen, -LB, -LA, -(SP)i-CC, -F, -Cl, -Br, -I, -OR37, -N(R37)2, - SO3, -PO3-, -NO2, -CF3, -SR37, S(=O)2N(R37)2, OC(=O)R37, SC(=O) R37, OC(=S)R37, SC(=S)R37, NR37C(=O)-R37, NR37C(=S)-R37, NR37C(=O)O-R37, NR37C(=S)O-R37, NR37C(=O)S-R37, NR37C(=S)S-R37, OC(=O)N(R37)2, SC(=O)N(R37)2, OC(=S)N(R37)2, SC(=S)N(R37)2, NR37C(=O)N(R37)2, NR37C(=S)N(R37)2, C(=O)R37,C(=S)R37,

[0525] C(=O)N(R37)2, C(=S)N(R37)2, C(=O)O-R37, C(=O)S-R37, C(=S)O-R37, C(=S)S-R37, S(O)R37, -S(O)2R37, NR37S(O)2R37, -ON(R37)2, -NR37OR37, C-1C4alkyl groups, C2-C4alkenyl groups, C2-C4alkynyl groups, C6-C8aryl groups, C2-C8heteroaryl groups, C3-C6cycloalkyl groups, C5-C6cycloalkenyl groups, C3-C10alkyl(hetero)aryl groups, C3-C10(hetero)arylalkyl groups, C4-C10alkylcycloalkyl groups, C4-C10cycloalkylalkyl groups, C5-C10cycloalkyl(hetero)aryl groups and C5-C10

[0526] (hetero)arylcycloalkyl groups, wherein the alkyl groups, alkenyl groups, alkynyl groups, aryl, heteroaryl, cycloalkyl groups, cycloalkenyl groups, alkyl(hetero)aryl groups, (hetero)arylalkyl groups, alkylcycloalkyl groups, cycloalkylalkyl groups, cycloalkyl(hetero)aryl groups and (hetero)arylcycloalkyl groups are optionally substituted with a moiety selected from the group consisting of -Cl, -F, -Br, -I, - OR37, -N(R37)2, -SO3R37, -PO3(R37)2, -PO4(R37)2, -NO2, -CF3, =O, =NR37, and -SR37, and optionally contain one or more heteroatoms selected from the group consisting of O, S, NR37, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized. R37

[0527] In Formula (1) each R37is independently selected from the group consisting of hydrogen, -LB, -LA, -(SP)i-CC, C1-C24alkyl groups, C2-C24alkenyl groups, C2-C24alkynyl groups, C6-C24aryl groups, C2-C24heteroaryl groups, C3-C24cycloalkyl groups, C5-C24cycloalkenyl groups, C12-C24cycloalkynyl groups, C3-C24

[0528] (cyclo)alkyl(hetero)aryl groups, C3-C24(hetero)aryl(cyclo)alkyl, C4-C24

[0529] (cyclo)alkenyl(hetero)aryl groups, C4-C24(hetero)aryl(cyclo)alkenyl groups, C4-C24(cyclo)alkynyl(hetero)aryl groups, C4-C24(hetero)aryl(cyclo) alkynyl groups, C4-C24alkylcycloalkyl groups, and C4-C24cycloalkylalkyl groups; wherein i is an integer in a range of from 0 to 4, preferably i is 1; the R37groups not being hydrogen are optionally substituted with a moiety selected from the group consisting of -Cl, -F, -Br, -I, -OH, -NH2, -SO3H, -PO3H, -PO4H2,-NO2, -CF3, =O, =NH, and -SH, and optionally contain one or more heteroatoms selected from the group consisting of O, S, NH, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized.

[0530] In preferred embodiments, R37is selected from the group consisting of hydrogen, -LB, -LA, -(SP)i-CC, C1-C8alkyl groups, C2-C8alkenyl groups, C2-C8alkynyl groups, C6-C12aryl, C2-C12heteroaryl, C3-C8cycloalkyl groups, C5-C8cycloalkenyl groups, C3-C12alkyl(hetero)aryl groups, C3-C12(hetero)arylalkyl groups, C4-C12alkylcycloalkyl groups, C4-C12cycloalkylalkyl groups, C5-C12cycloalkyl(hetero)aryl groups and C5-C12(hetero)arylcycloalkyl groups, wherein the R37groups not being hydrogen are optionally substituted with a moiety selected from the group consisting of -Cl, -F, -Br, -I, -OH, -NH2, -SO3H, -PO3H,- PO4H2,-NO2, -CF3, =O, =NH, and -SH, and optionally contain one or more heteroatoms selected from the group consisting of O, S, NH, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized.

[0531] In preferred embodiments, R37is selected from the group consisting of hydrogen, -LB, -LA, -(SP)i-CC, C1-C4alkyl groups, C2-C4alkenyl groups, C2-C4alkynyl groups, C6-C8aryl, C2-C8heteroaryl, C3-C6cycloalkyl groups, C5-C6cycloalkenyl groups, C3-C10alkyl(hetero)aryl groups, C3-C10(hetero)arylalkyl groups, C4-C8alkylcycloalkyl groups, C4-C8cycloalkylalkyl groups, C5-C10cycloalkyl(hetero)aryl groups and C5-C10(hetero)arylcycloalkyl groups, wherein the R37groups not being hydrogen are optionally substituted with a moiety selected from the group consisting of -Cl, -F, -Br, -I, -OH, -NH2, -SO3H, -PO3H,- PO4H2,-NO2, -CF3, =O, =NH, and -SH, and optionally contain one or more heteroatoms selected from the group consisting of O, S, NH, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized.

[0532] In preferred embodiments, the R37groups not being hydrogen are not

[0533] substituted. In preferred embodiments, the R37groups not being hydrogen do not contain heteroatoms. In some preferred embodiments, R37is hydrogen. SPis a spacer as defined herein and CCis a Construct-C as defined herein.

[0534] In Formula (1) two R47and / or R37are optionally comprised in a ring.

[0535] In Formula (1) two R47and / or R37are optionally comprised in a ring so as to form a ring fused to the eight-membered trans-ring of Formula (1). It is preferred that when two R47and / or R37groups are comprised in a ring so as to form a ring fused to the eight-membered trans-ring, that these rings fused to the eight-membered trans-ring are C3-C7cycloalkylene groups and C4-C7

[0536] cycloalkenylene groups, optionally substituted and containing heteroatoms as described for R47. Label

[0537] The compound of Formula (1) comprises a Label that is capable of providing the desired diagnostic, imaging, and / or radiotherapeutic effect.

[0538] The Label is a moiety comprising a radionuclide.

[0539] Especially for imaging applications, it is preferred that the Label is a detectable label. A "detectable label" as used herein relates to the part of the compound of Formula (1) which allows detection of the compound of Formula (1) when present in a cell, tissue or organism. One type of detectable label envisaged within the context of the present invention is a contrast providing label. Different types of detectable labels are envisaged within the context of the present invention and are described hereinbelow.

[0540] Thus, according to a particular embodiment of the present invention, the compounds, combinations, kits, and methods of the present invention are used in imaging, especially medical imaging. In order to identify the Primary Target and / or to evaluate the biodistribution of the compound of Formula (1), use is made of a detectable Label.

[0541] Preferred detectable labels for imaging are contrast-providing moieties used in traditional imaging systems.

[0542] Preferably, the radionuclide comprised in a Label for imaging is an isotope selected from the group consisting of3H,11C,13N,15O,18F,19F,44Sc,51Cr,52Fe,52Mn,55Co,60Cu,61Cu,62Zn,62Cu,63Zn,64Cu,66Ga,67Ga,68Ga,70As,71As,

[0543] 72As,74As,75Se,75Br,76Br,77Br,8OBr,82Br,82Rb,86Y,88Y,89Sr,89Zr,97Ru,99mTc,110In,111In,113In,114In,117Sn,120I,122Xe,123I,124I,125I,166Ho,167Tm,169Yb,193Pt,195Pt,201Tl, and203Pb.

[0544] More preferably, the radionuclide comprised in a Label for imaging is an isotope selected from the group consisting of18F,44Sc,64Cu,68Ga,89Zr,99mTc,111In,123I, and124I.

[0545] Other elements and isotopes, such as being used for therapy may also be applied for imaging in certain applications.

[0546] In one embodiment the detectable labels comprise small size organic PET and SPECT radioisotopes, such as18F,11C ,123I or124I. Due to their small size, organic PET or SPECT radioisotopes are ideally suited for monitoring intracellular events as they do not greatly affect the properties of the Administration Agent in general and its membrane transport in particular.

[0547] In preferred embodiments, especially when the compound of Formula (1) is used in therapeutic applications, the Label is a therapeutic Label, said Label comprising a radioactive isotope for radiation therapy. A radionuclide used for therapy is preferably an isotope selected from the group consisting of24Na,32P,33P,47Sc,59Fe,67Cu,76As,77As,80Br,82Br,89Sr,90Nb,90Y,103Ru,105Rh,109Pd,111Ag,111In,121Sn,127Te,131I,140La,141Ce,142Pr,143Pr,144Pr,149Pm,149Tb,151Pm,153Sm,159Gd,161Tb,165Dy,166Dy,166Ho,169Er,172Tm,175Yb,177Lu,

[0548] 186Re,188Re,198Au,199Au,211At,211Bi,212Bi,212Pb,213Bi,214Bi,223Ra,224Ra,225Ac, and227Th.

[0549] More preferably, the radionuclide comprised in a Label for therapy is an isotope selected from the group consisting of90Y,111In,131I,177Lu,186Re,188Re,211At,212Pb,213Bi,225Ac, and227Th.

[0550] When the Label is intended to comprise a metal, such as111In for SPECT imaging, such is preferably provided in the form of a chelate. In such a case the Label preferably comprises a structural moiety capable of forming a coordination complex with such a metal. A good example hereof are macrocylic lanthanide(III) chelates derived from l,4,7,10-tetraazacyclododecane-l,4,7,10-tetraacetic acid (H4dota).

[0551] In preferred embodiments, the Label is selected from the group consisting of -OR37, -N(R37)2, -CF3, -SR37, S(=O)2N(R37)2, OC(=O)R37, SC(=O) R37, OC(=S)R37, SC(=S)R37, NR37C(=O)-R37, NR37C(=S)-R37, NR37C(=O)O-R37, NR37C(=S)O-R37, NR37C(=O)S-R37, NR37C(=S)S-R37, OC(=O)N(R37)2, SC(=O)N(R37)2, OC(=S)N(R37)2, SC(=S)N(R37)2, NR37C(=O)N(R37)2, NR37C(=S)N(R37)2, C(=O)R37,C(=S)R37,

[0552] C(=O)N(R37)2, C(=S)N(R37)2, C(=O)O-R37, C(=O)S-R37, C(=S)O-R37, C(=S)S-R37, S(O)R37, -S(O)2R37, NR37S(O)2R37, -ON(R37)2,-NR37OR37, CI-C24alkyl groups, C2- C24alkenyl groups, C2-C24alkynyl groups, C6-C24aryl groups, C2-C24heteroaryl groups, C3-C24cycloalkyl groups, C5-C24cycloalkenyl groups, C12-C24cycloalkynyl groups, C3-C24(cyclo)alkyl(hetero)aryl groups, C3-C24(hetero)aryl(cyclo) alkyl, C4- C24(cyclo)alkenyl(hetero)aryl groups, C4-C24(hetero)aryl(cyclo)alkenyl groups, C4- C24(cyclo)alkynyl(hetero)aryl groups, C4-C24(hetero)aryl(cyclo)alkynyl groups, C4-C24alkylcycloalkyl groups, and C4-C24cycloalkylalkyl groups;

[0553] the R37groups, alkyl groups, alkenyl groups, alkynyl groups, aryl, heteroaryl, cycloalkyl groups, cycloalkenyl groups, cycloalkynyl groups,

[0554] (cyclo)alkyl(hetero)aryl groups, (hetero)aryl(cyclo) alkyl groups,

[0555] (cyclo)alkenyl(hetero)aryl groups, (hetero)aryl(cyclo)alkenyl groups,

[0556] (cyclo)alkynyl(hetero)aryl groups, (hetero)aryl(cyclo)alkynyl groups,

[0557] alkylcycloalkyl groups, cycloalkylalkyl groups comprise, are substituted with, and / or chelating at least one isotope selected from the group consisting of3H,11C,13N,15O,18F,19F,51Cr,52Fe,52Mn,55Co,60Cu,61Cu,62Zn,62Cu,63Zn,64Cu,66Ga,67Ga,68Ga,70As,71As,72As,74As,75Se,75Br,76Br,77Br,80Br,82Br,82Rb,86Y,88Y,9°Y,89Sr,89Zr,97Ru,99mTc,110In,111In,113In,114In,117Sn,120I,122Xe,123I,124I,125I,166Ho,167Tm,169Yb,193Pt,195Pt,201T1,203Pb,24Na,32P,33P,47Sc,59Fe,67Cu,76As,77As,90Nb,103Ru,105Rh,109Pd,111Ag,121Sn,127Te,131I,140La,141Ce,142Pr,

[0558] 143Pr,144Pr,149Pm,149Tb,161Pm,153Sm,159Gd,161Tb,165Dy,166Dy166Ho,169Er,

[0559] 172Tm,175Yb,177Lu,186Re,188Re,198Au,199Au,211At,211Bi,212Bi,212Pb,213Bi,214Bi,223Ra,224Ra,225Ac and227Th,

[0560] and are optionally further substituted with a moiety selected from the group consisting of -Cl, -F, -Br, -I, -OR37, -N(R37)2, -SO3R37, -PO3(R37)2, -PO4(R37)2, -NO2, - CF3, =O,— NR37, and -SR37, and optionally contain one or more heteroatoms selected from the group consisting of O, S, NR37, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized.

[0561] In another preferred embodiment, the Label is selected from the group consisting of -OR37, -N(R37)2, -CF3, -SR37, S(=O)2N(R37)2, OC(=O)R37, SC(=O)R37, OC(=S)R37, SC(=S)R37, NR37C(=O)-R37, NR37C(=S)-R37, NR37C(=O)O-R37,

[0562] NR37C(=S)O-R37, NR37C(=O)S-R37, NR37C(=S)S-R37, OC(=O)N(R37)2,

[0563] SC(=O)N(R37)2, OC(=S)N(R37)2, SC(=S)N(R37)2, NR37C(=O)N(R37)2,

[0564] NR37C(=S)N(R37)2, C(=O)R37,C(=S)R37,C(=O)N(R37)2, C(=S)N(R37)2, C(=O)O-R37, C(=O)S-R37, C(=S)O-R37, C(=S)S-R37,C1-C12alkyl groups, C2-C12alkenyl groups, C2-C12alkynyl groups, C6-C12aryl groups, C2-C12heteroaryl groups, C3-C12cycloalkyl groups, C5-C12cycloalkenyl groups, C12-C12cycloalkynyl groups, C3-C12(cyclo)alkyl(hetero)aryl groups, C3-C12(hetero)aryl(cyclo)alkyl, C4-C12 (cyclo)alkenyl(hetero)aryl groups, C4-C12(hetero)aryl(cyclo) alkenyl groups, C4-C12(cyclo)alkynyl(hetero)aryl groups, C4-C12(hetero)aryl(cyclo)alkynyl groups, C4-C12alkylcycloalkyl groups, and C4-C12cycloalkylalkyl groups;

[0565] the R37groups, alkyl groups, alkenyl groups, alkynyl groups, aryl, heteroaryl, cycloalkyl groups, cycloalkenyl groups, cycloalkynyl groups,

[0566] (cyclo)alkyl(hetero)aryl groups, (hetero)aryl(cyclo) alkyl groups,

[0567] (cyclo)alkenyl(hetero)aryl groups, (hetero)aryl(cyclo)alkenyl groups,

[0568] (cyclo)alkynyl(hetero)aryl groups, (hetero)aryl(cyclo)alkynyl groups,

[0569] alkylcycloalkyl groups, cycloalkylalkyl groups comprise, are substituted with, and / or chelating at least one isotope selected from the group consisting of3H,11C,13N,150,18F,19F,44Sc,51Cr,52Fe,52Mn,55Co,60Cu,61Cu,62Zn,62Cu,63Zn,64Cu,66Ga,67Ga,68Ga,70As,71As,72As,74As,75Se,75Br,76Br,77Br,8°Br,82Br,82Rb,86Y,88Y,90Y,89Sr,89Zr,97Ru,99mTc,110In,111In,113In,114In,117Sn,120I,122Xe,123I,124I,125I,166Ho,167Tm,169Yb,193Pt,195Pt,201T1,203Pb,24Na,32P,33P,47Sc,59Fe,67Cu,

[0570] 76As,77As,90Nb,103Ru,105Rh,109Pd,111Ag,121Sn,127Te,131I,140La,141Ce,142Pr,143Pr,144Pr,149Pm,149Tb,151Pm,153Sm,159Gd,161Tb,165Dy,166Dy,166Ho,169Er,172Tm,175Yb,177Lu,186Re,188Re,198Au,199Au,211At,211Bi,212Bi,212Pb,213Bi,214Bi,223Ra,224Ra,225Ac, and227Th,

[0571] and are optionally further substituted with a moiety selected from the group consisting of -Cl, -F, -Br, -I, -OR37, -N(R37)2, -SO3R37, -PO3(R37)2, -PO4(R37)2, -NO2, - CF3, =O,— NR37, and -SR37, and optionally contain one or more heteroatoms selected from the group consisting of O, S, NR37, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized.

[0572] In preferred embodiments, each Label is independently selected from the group consisting of -OR37, -N(R37)2, -CF3, -SR37, S(=O)2N(R37)2, OC(=O)R37, SC(=O)R37, OC(=S)R37, SC(=S)R37, NR37C(=O)-R37, NR37C(=S)-R37, NR37C(=O)O- R37, NR37C(=S)O-R37, NR37C(=O)S-R37, NR37C(=S)S-R37, OC(=O)N(R37)2,

[0573] SC(=O)N(R37)2, OC(=S)N(R37)2, SC(=S)N(R37)2, NR37C(=O)N(R37)2,

[0574] NR37C(=S)N(R37)2, C(=O)R37,C(=S)R37,C(=O)N(R37)2, C(=S)N(R37)2, C(=O)O-R37, C(=O)S-R37, C(=S)O-R37, C(=S)S-R37,C1-C6alkyl groups, C2-C6alkenyl groups, C2- C6alkynyl groups, C6aryl groups, C2-C6heteroaryl groups, C3-C6cycloalkyl groups, C5-C6cycloalkenyl groups, C8cycloalkynyl groups, C3-C6 (cyclo)alkyl(hetero)aryl groups, C3-C6(hetero)aryl(cyclo)alkyl, C4-C6(cyclo)alkenyl(hetero)aryl groups, C4-C6(hetero)aryl(cyclo)alkenyl groups, C4-C6(cyclo)alkynyl(hetero)aryl groups, C4-C6(hetero)aryl(cyclo)alkynyl groups, C4-C6alkylcycloalkyl groups, and C4-C6cycloalkylalkyl groups;

[0575] the R37groups, alkyl groups, alkenyl groups, alkynyl groups, aryl, heteroaryl, cycloalkyl groups, cycloalkenyl groups, cycloalkynyl groups,

[0576] (cyclo)alkyl(hetero)aryl groups, (hetero)aryl(cyclo) alkyl groups,

[0577] (cyclo)alkenyl(hetero)aryl groups, (hetero)aryl(cyclo)alkenyl groups,

[0578] (cyclo)alkynyl(hetero)aryl groups, (hetero)aryl(cyclo)alkynyl groups,

[0579] alkylcycloalkyl groups, cycloalkylalkyl groups comprise, are substituted with and / or chelating at least one isotope selected from the group consisting of3H,11C,13N,15O,18F,19F,44Sc,51Cr,52Fe,52Mn,55Co,60Cu,61Cu,62Zn,62Cu,63Zn,64Cu,66Ga,67Ga,68Ga,70As,71As,72As,74As,75Se,75Br,76Br,77Br,8OBr,82Br,82Rb,86Y,88Y,9°Y,89Sr,89Zr,97Ru,99mTc,110In,111In,113In,114In,117Sn,120I,122Xe,123I,124I,125I,166Ho,167Tm,169Yb,193Pt,195Pt,201T1,203Pb,24Na,32P,33P,47Sc,59Fe,67Cu,

[0580] 76As,77As,90Nb,103Ru,105Rh,109Pd,111Ag,121Sn,127Te,131I,140La,141Ce,

[0581] 142Pr,143Pr,144Pr,149Pm,149Tb,151Pm,153Sm,159Gd,161Tb,165Dy,166Dy,166Ho,169Er,172Tm,175Yb,177Lu,186Re,188Re,198Au,199Au,211At,211Bi,212Bi,212Pb,213Bi,214Bi,223Ra,224Ra,225Ac, and227Th,

[0582] and are optionally further substituted with a moiety selected from the group consisting of -Cl, -F, -Br, -I, -OR37, -N(R37)2, -SO3R37, -P03(R37)2, -P04(R37)2, -NO2, - CF3, =O,— NR37, and -SR37, and optionally contain one or more heteroatoms selected from the group consisting of O, S, NR37, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized.

[0583] In a preferred embodiment the Label is derived from a prosthetic group. The person skilled in the art will understand that a prosthetic group is a precursor that can be radiolabeled with a radionuclide like131I thus forming the Label.

[0584] In another preferred embodiment, the Label is selected from the group consisting of C1-C12alkyl groups, C2-C12alkenyl groups, C2-C12alkynyl groups, C6-C12aryl groups, C2-C12heteroaryl groups, C3-C12cycloalkyl groups, C5-C12cycloalkenyl groups, C12-C12cycloalkynyl groups, C3-C12(cyclo)alkyl(hetero)aryl groups, C3-C12(hetero)aryl(cyclo)alkyl, C4-C12(cyclo)alkenyl(hetero)aryl groups, C4-C12(hetero)aryl(cyclo)alkenyl groups, C4-C12(cyclo)alkynyl(hetero)aryl groups, C4-C12(h etero) aryl (cyclo) alky nyl groups, C4-C12alkylcycloalkyl groups, and C4- C12cycloalkylalkyl groups; said groups comprise, or are substituted with, at least one isotope selected from the group consisting of3H,11C,13N,15O,18F,19F,75Br,76Br,77Br,80Br,82Br,120I,123I,124I,125I,32P,33P,131I, and211At;

[0585] and are optionally further substituted with a moiety selected from the group consisting of -Cl, -F, -Br, -I, -OR37, -N(R37)2, -SO3R37, -PO3(R37)2, -PO4(R37)2, -NO2, - CF3, =O,— NR37, and -SR37, and optionally contain one or more heteroatoms selected from the group consisting of O, S, NR37, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized.

[0586] In a preferred embodiment the Label comprises a chelating moiety.

[0587] In a preferred embodiment, the Label is a chelating moiety selected from the group consisting of conjugates of DTPA (diethylenetriaminepentaacetic acid), DOTA (1,4,7,10- tetraazacyclododecane-N,N',N",N"-tetraacetic acid), DOTAGA anhydride (2,2',2”-(10-(2,6-dioxotetrahydro-2H-pyran-3-yl)-l,4,7,10- tetraazacyclododecane-l,4,7-triyl)triacetic acid), NOTA (1,4,7-triazacyclononane- N,N',N"-triacetic acid), TETA (l,4,8,ll-tetraazacyclotetradecane-N,N',N",N'- tetraacetic acid), OTTA (Nl-(p-isothiocyanatobenzyl)-diethylenetriamine- Ni,N2,N3,N3-tetraacetic acid), deferoxamine or DFO (N'- [5- [[4-[[5- (acetylhy droxy amino)pentyl] amino] - 1 , 4- dioxobutyl] hydroxy amino] pentyl] - N- (5 - aminopentyl)-N-hydroxybutanediamide), and the DFO derivative called DFO*, and HYNIC (hydrazino nicotinamide); and the chelating moiety chelates a metal selected from the group consisting of44Sc,51Cr,52Fe,52Mn,55Co,60Cu,61Cu,62Zn,62Cu,63Zn,64Cu,66Ga,67Ga,68Ga,70As,71As,72As,74As,75Se,82Rb,86Y,88Y,89Sr,89Zr,97Ru,99mTc,110In,111In,113In,114In,117Sn,122Xe,166Ho,167Tm,169Yb,193Pt,196Pt,201T1,203Pb,24Na,47Sc,59Fe,67Cu,76As,77As,89Sr,90Nb,90Y,103Ru,105Rh,109Pd,111Ag,111In,121Sn,127Te,140La,141Ce,142Pr,143Pr,144Pr,149Pm,149Tb,151Pm,153Sm,159Gd,161Tb,165Dy,166Dy,166Ho,169Er,172Tm,175Yb,177Lu,

[0588] 186Re,188Re,198Au,199Au,211At,211Bi,212Bi,212Pb,213Bi,214Bi,223Ra,224Ra,225Ac, and227Th. In a preferred embodiment the metal chelate comprises an acyclic derivative of ethylenediaminotetraacetic acid (EDTA) or diethylenediaminotetraacetic acid (DTP A):

[0589]

[0590] , wherein the dashed line denotes a bond to the rest of the molecule.

[0591] In another preferred embodiment the metal chelate comprises an acyclic chelator containing carboxy-pyridine groups:

[0592]

[0593] , wherein the dashed line denotes a bond to the rest of the molecule.

[0594] In another preferred embodiment the metal chelate comprises a cyclic derivative of 1,4,7, 10-tetraazadodecane (cyclen):

[0595]

[0596] , wherein the dashed line denotes a bond to the rest of the molecule.

[0597] In another preferred embodiment the metal chelate comprises a derivative of 1,4,7-triazacyclononane (TACN):

[0598]

[0599] , wherein the dashed line denotes a bond to the rest of the molecule.

[0600] In yet another preferred embodiment the metal chelate comprises a macrocyclic chelator containing N and O heteroatoms:

[0601] , wherein the dashed line denotes a bond to the rest of the molecule.

[0602] In another preferred embodiment the metal chelate comprises a derivative of the cryptand agent sarcophagine (Sar):

[0603]

[0604] , wherein the dashed line denotes a bond to the rest of the molecule.

[0605] In another preferred embodiment the metal chelate comprises a linear or cyclic chelator containing hydroxamate groups:

[0606]

[0607] , wherein the dashed line denotes a bond to the rest of the molecule.

[0608] In yet another preferred embodiment the metal chelate comprises a linear or cyclic chelator containing 3-hydroxy-4-pyridinone (3,4-HOPO) groups:

[0609]

[0610] , wherein the dashed line denotes a bond to the rest of the molecule.

[0611] In another preferred embodiment the metal chelate comprises a linear or cyclic chelator containing N, S and P heteroatoms:

[0612]

[0613] , wherein the dashed line denotes a bond to the rest of the molecule M denotes a radionuclide selected from the group consisting of99mTc,186Re, and188Re.

[0614] In another preferred embodiment the metal chelate comprises glycine, serine, cysteine, lysine and alanine residues:

[0615]

[0616] , wherein the dashed line denotes a bond to the rest of the molecule M denotes a radionuclide selected from the group consisting of99mTc,186Re, and188Re.

[0617] In another preferred embodiment the metal chelate contains

[0618] hydrazinonicotinic acid (HYNIC) and a co-ligand:

[0619]

[0620] , wherein the dashed line denotes a bond to the rest of the molecule M denotes a radionuclide selected from the group consisting of99mTc,186Re, and188Re.

[0621] In another preferred embodiment the chelate comprises carbonyl groups and a chelator containing N, O and S heteroatoms or a cyclopentadienyle:

[0622]

[0623] , wherein the dashed line denotes a bond to the rest of the molecule M denotes a radionuclide selected from the group consisting of99mTc,186Re, and188Re.

[0624] In some preferred embodiments of the present invention the label contains18F and can be produced by the skilled person on the basis of known synthesis routes using known labeled synthons or prosthetic groups. Several non limiting examples of18F-containing labels are depicted below:

[0625]

[0626] , wherein the dashed line denotes a bond to the rest of the molecule.

[0627] In preferred embodiments of the present invention the label contains at least one isotope selected from the group consisting of123I,124I,125I,131I, and211At; and is synthesized by the skilled person on the basis of known synthesis routes using prosthetic groups. Several preferred embodiments of such labels are depicted below:

[0628]

[0629] , wherein the dashed line denotes a bond to the rest of the molecule and X denotes123I,124I,125I,131I or211At.

[0630] In yet another preferred embodiment of the present invention the label contains at least one isotope selected from the group consisting of123I,124I,125I,131I, and211At;and is synthetized by the skilled person on the basis of known synthesis routes using a closo-decaborate(2-) group:

[0631] , wherein the dashed line denotes a bond to the rest of the molecule and X denotes123I,124I,125I,131I or211At.

[0632] Administration Agent

[0633] The Administration Agent is an antibody. The Administration Agent can be any construct of which it is desired to modify it with a Label for radio-imaging or radiotherapy and of which it is desired to remove its imaging or radiotherapy label at a particular time after injection. This particularly is the case in the event of targeted imaging and radiotherapy to a site, such as a tumor, within the body of a subject, notably a human subject. The sole requirement is that it can be provided with a Trigger TR, which is further linker to a Label. The precise linkage of the Trigger to the Administration Agent will depend on the molecular structure of both, but it should be noted that this does not normally present a particular challenge to the person skilled in the art, as many proven conjugation methods and linkage moieties for various biomolecules exist. The linkage can, optionally, be via a spacer such as a polyethylene glycol (PEG) chain.

[0634] Typically the Administration Agent can bind to a Primary Target, as defined herein. Said Primary Target can be a target to which a Targeting Agent binds or it can be a therapeutic target upon which a drug has its effect. In a preferred embodiment the Primary Target is a therapeutic target and the

[0635] Targeting Agent is a drug and binds said Primary Target.

[0636] In preferred embodiments, the Administration Agent is a Targeting Agent as defined herein, insofar the Targeting Agent is described as an antibody.

[0637] In other preferred embodiments, the Administration Agent equals a Targeting Agent, and the Targeting Agent is radiolabeled with a therapeutic radioisotope in order to target therapeutic radiation to tissues expressing a Primary Target. In other preferred embodiments, the Administration Agent equals a Targeting Agent, and the Targeting Agent is radiolabeled with a diagnostic radioisotope in order to image tissues expressing a Primary Target.

[0638] In preferred embodiments, the Administration Agent is an antibody that comprises an FcRn binding domain, more preferably an intact IgG antibody. Preferably, the Administration Agent is an intact antibody.

[0639] In other preferred embodiments, the Administration Agent is an antibody that comprises an albumin-binding moiety.

[0640] In other preferred embodiments the Administration Agent equals a drug. In other preferred embodiments the Administration Agent equals a drug and the drug is labeled using the presented invention for the purpose of imaging in vivo drug distribution. Drugs that can be used in an Administration Agent relevant to this invention are pharmaceutically active compounds.

[0641] In a preferred embodiment the pharmaceutically active compound or drug is selected from the group consisting of cytotoxins, antiproliferative / antitumor agents, antiviral agents, antibiotics, anti-inflammatory agents, chemosensitizing agents, radiosensitizing agents, immunomodulators, immunosuppressants, immunostimulants, anti-angiogenic factors, and enzyme inhibitors.

[0642] In other preferred embodiments the drug is designed to act in the central neural system, for example in the context of Alzheimer’s disease and Parkinsons’ disease, for example antibodies against beta-amyloid and Tau proteins.

[0643] Exemplary cytotoxic drug types, for example for use in cancer therapy, include but are not limited to DNA damaging agents, DNA crosslinkers, DNA binders, DNA alkylators, DNA intercalators, DNA cleavers, microtubule stabilizing and destabilizing agents, topoisomerases inhibitors, radiation sensitizers, anti-metabolites, natural products and their analogs, peptides, oligonucleotides, enzyme inhibitors such as dihydrofolate reductase inhibitors and thymidylate synthase inhibitors.

[0644] Exemplary immunemodulators are antibodies against PD-L1, PD-1, LAG- 3, OX40, TIGIT, TIM-3, B7H4, Vista, CTLA-4, APRIL, GITR, CD3, CD28, CD40, CD74, RIG, MDA-5, NLRP1, NLRP3, AIM2, IDO, MEK, cGAS, and CD25, NKG2A. It will be understood that chemical modifications may also be made to the

[0645] Administration Agent in order to make reactions of that compound more convenient for purposes of preparing conjugates of the invention.

[0646] In a preferred embodiment, the Administration Agent before conjugation to the remainder of the compound of Formula (1) comprises at least one moiety selected from the group consisting of -OH, -NHR’, -CO2H, -SH, -S-S-, -SCH3-, -N3, terminal alkynyl, terminal alkenyl, -C(O)R', C8-C12(hetero)cycloalkynyl, nitrone, nitrile oxide, (imino)sydnone, isonitrille, and (oxa)norbornene, tetrazine, wherein R' equals R37, said moiety used for conjugation to a moiety comprising the dienophile, the Label and R32so as to form the compound satisfying Formula (1), and comprising a CM2or Cxmoiety.

[0647] In preferred embodiments the Administration Agent is bound to the remainder of the compound of Formula (1) via a CM2selected from the group consisting of amine, amide, thioamide, aminooxy, carbamate, thiocarbamate, urea, thiourea, sulfonamide, and sulfoncarbamate.

[0648] In preferred embodiments CM2equals R10as defined herein.

[0649] In a preferred embodiment, when the Administration Agent is conjugated via -SH or -S-S-, then CM2is selected from the group consisting of

[0650] wherein the wiggly line denotes a bond to the remaining part of the molecule, and wherein the dashed line denotes a bond to the Administration Agent, wherein R' equals R37as defined herein. In a preferred embodiment, when the Administration Agent is conjugated via -SCH3- then CM2preferably is:

[0651]

[0652] wherein the wiggly line denotes a bond to the remaining part of the molecule, and wherein the dashed line denotes a bond to the Administration Agent.

[0653] In a preferred embodiment, when the Administration Agent is conjugated via -NR’-, then CM2is selected from the group consisting of

[0654]

[0655] wherein R' equals R37as defined herein, wherein the wiggly line denotes a bond to the remaining part of the molecule, and wherein the dashed line denotes a bond to the Administration Agent.

[0656] In a preferred embodiment, when the Administration Agent is conjugated via -C- derived from a moiety that was -C(O)R’ or -C(O)R’-, then CM2is selected from the group consisting of

[0657] wherein the wiggly line denotes a bond to the remaining part of the molecule, and wherein the dashed line denotes a bond to the Administration Agent.

[0658] In a preferred embodiment, when the Administration Agent is conjugated via -C(O)- derived from a moiety that was -C(O)OH, then CM2is selected from the group consisting of wherein R' equals R37as defined herein, wherein

[0659] the wiggly line denotes a bond to the remaining part of the molecule, and wherein the dashed line denotes a bond to the Administration Agent.

[0660] In a preferred embodiment, when the Administration Agent is conjugated via -O-, then CM2is selected from the group consisting of wherein R' equals R37as defined herein, wherein the wiggly line denotes a bond to the remaining part of the molecule, and wherein the dashed line denotes a bond to the Administration Agent.

[0661] In a preferred embodiment, when the Administration Agent is conjugated via -N3that was reacted with an R32that comprised an alkyne group, then the resulting Cxcomprises a triazole ring, wherein each Cxis independently selected from the group consisting of

[0662]

[0663] , and ; wherein the wiggly line denotes a bond to the remaining part of the molecule, and wherein the dashed line denotes a bond to the Administration Agent.

[0664] Preferably, the Administration Agent is modified with further moieties that equal Formula (1), except that these further moieties do not comprise an Administration Agent (as the first mentioned Administration Agent is already coupled to said moiety). In a preferred embodiment, the Administration Agent is coupled to further moieties as defined in this paragraph at 1 to 8 positions, more preferably from 1 to 6 positions, even more preferably at 1 to 4 positions.

[0665] Further embodiments in relation to the compound of Formula (1)

[0666] In the compound of the invention the Administration Agent is an antibody.

[0667] In a preferred embodiment, in the compound of the invention the Label is a radiolabel, preferably a chelating moiety that chelates a radioisotope.

[0668] The skilled person is familiar with the fact that the dienophile activity is not necessarily dependent on the presence of all carbon atoms in the ring, since also heterocyclic monoalkenylene eight-membered rings are known to possess dienophile activity. Thus, in general, the invention is not limited to strictly trans- cyclooctene. The person skilled in organic chemistry will be aware that other eight-membered ring-based dienophiles exist, which comprise the same

[0669] endocyclic double bond as the trans-cyclooctene, but which may have one or more heteroatoms elsewhere in the ring. I.e., the invention generally pertains to eight- membered non-aromatic cyclic alkenylene moieties, preferably a cyclooctene moiety, and more preferably a trans-cyclooctene moiety.

[0670] Trans-cyclooctene or E-cyclooctene derivatives are very suitable as

[0671] Triggers, especially considering their high reactivity. Optionally, the trans- cyclooctene (TCO) moiety comprises at least two exocyclic bonds fixed in substantially the same plane, preferably as described in WO 2012 / 156919A1, and / or it optionally comprises at least one substituent in the axial position, and not the equatorial position. The person skilled in organic chemistry will understand that the term“fixed in substantially the same plane” refers to bonding theory according to which bonds are normally considered to be fixed in the same plane. Typical examples of such fixations in the same plane include double bonds and strained fused rings. E.g., the at least two exocyclic bonds can be the two bonds of a double bond to an oxygen (i.e. C=O). The at least two exocyclic bonds can also be single bonds on two adjacent carbon atoms, provided that these bonds together are part of a fused ring (i.e. fused to the TCO ring) that assumes a substantially flat structure, therewith fixing said two single bonds in substantially one and the same plane. Examples of the latter include strained rings such as cyclopropyl and cyclobutyl. Without wishing to be bound by theory, the inventors believe that the presence of at least two exocyclic bonds in the same plane will result in an at least partial flattening of the TCO ring, which can lead to higher reactivity in the IEDDA reaction. A background reference providing further guidance is WO 2012 / 153254. The at least two exocyclic bonds fixed in substantially the same plane are preferably as described on page 16 and further of WO 2012 / 156919 Al.

[0672] TCO moieties may consist of multiple isomers, also comprising the equatorial vs. axial positioning of substituents on the TCO. In this respect, reference is made to Whitham et al. J. Chem. Soc. (C), 1971, 883-896, describing the synthesis and characterization of the equatorial and axial isomers of trans- cyclo-oct-2-en-ol, identified as (IRS, 2RS) and (1SR, 2RS), respectively. In these isomers the OH substituent is either in the equatorial or axial position. Without wishing to be bound by theory, the inventors believe that the presence of an axial substituent increases the TCO ring strain resulting in higher reactivity in the IEDDA reaction. A background reference providing further guidance is WO 2012 / 049624.

[0673] Furthermore, in case of allylic substituents on the TCO in some

[0674] embodiments it is preferred that these are positioned axially and not

[0675] equatorially.

[0676] It should be noted that, depending on the choice of nomenclature, the TCO dienophile may also be denoted E-cyclooctene. With reference to the conventional nomenclature, it will be understood that, as a result of substitution on the cyclooctene ring, depending on the location and molecular weight of the substituent, the same cyclooctene isomer may formally become denoted as a Z- isomer. In the present invention, any substituted variants of the invention, whether or not formally“E” or“Z,” or“cis” or“trans” isomers, will be considered derivatives of unsubstituted trans-cyclooctene, or unsubstituted E-cyclooctene. The terms’’trans-cyclooctene” (TCO) as well as E-cyclooctene are used

[0677] interchangeably and are maintained for all dienophiles according to the present invention, also in the event that substituents would formally require the opposite nomenclature. I.e., the invention relates to cyclooctene in which carbon atoms 1 and 6 as numbered below are in the E ( entgegen ) or trans position.

[0678]

[0679] The dienophiles for use in the invention can be synthesized by the skilled person, on the basis of known synthesis routes to cyclooctenes and corresponding hetero atom(s) -containing rings. The skilled person further is aware of the wealth of cyclooctene derivatives that can be synthesized via the ring closing metathesis reaction using Grubbs catalysts. As mentioned above, the TCO possibly includes one or more heteroatoms in the ring. This is as such sufficiently accessible to the skilled person [e.g. WO2016025480]. Reference is made, e.g., to the presence of a thioether in TCO: [Cere et al. J. Org. Chem. 1980, 45, 261]. Also, e.g., an - O-S1R2- O moiety in TCO: [Prevost et al. J. Am. Chem. Soc. 2009, 131, 14182] References to TCO syntheses wherein the allylic positioned leaving group (R48) is an ether, ester, carbonate, carbamate or a thiocarbamate are: [Versteegen et al Angew. Chem. Int. Ed. 2018, 57, 10494], and [Steiger et al Chem Comm 2017, 53, 1378]. Exemplary TCOs include the following structures, indicated below with

[0680] literature references. Where a cyclooctene derivative is depicted as a Z- cyclooctene it is conceived that this can be converted to the E-cyclooctene analog.

[0681]

[0682] In a preferred embodiment, the compound of Formula (1) satisfies any one of the following structures:

[0683]

[0684] = rest of attached CBor SP-CB

[0685] = rest of attached CAor LC-CA, optionally comprising CBor SP-CB, wherein CAis optionally bound to remainder of the molecule via SP

[0686]

[0687] rest of attached CBor SP-CB

[0688] rest of attached CAor LC-CA, optionally comprising CBor SP-CB, wherein CAis optionally bound to remainder of the molecule via SP

[0689]

[0690] = rest of attached CBor SP-CB

[0691] = rest of attached CAor LC-CA, optionally comprising CBorSP-CB,

[0692] wherein CAis optionally bound to remainder of the molecule via SP

[0693] In a preferredembodiment,the compoundof Formula(1) is any one of the racemic and enantiomericallypure compounds listed below:

[0694]

[0695] wherein the wiggly line indicates a bond to the remainder of the compound of Formula (1).

[0696] Especially preferred compounds of Formula (1) are the enantiomerically pure compounds listed below:

[0697]

[0698] wherein the wiggly line indicates a bond to the remainder of the compound of Formula (1).

[0699] Other preferred compounds of Formula (1) are:

[0700]

[0701] - - - = bond to remainder of R47

[0702] In preferred embodiments, LAnot being R48, LBnot being R48, the Label, the Administration Agent, R98, and / or CCare bound to the remainder of the compound of Formula (1) via a residue of R32, or a moiety CM2or Cxas defined herein, wherein preferably said residue of R32or a moiety CM2or Cxequals or is comprised in a Spacer. A person skilled in the art will understand that "residue of R32" means the conjugation reaction product of R32with another chemical group so as to form a conjugate, for example between CCwith the remainder of the compound according to Formula (1).

[0703] In preferred embodiments, LAnot being R48, LBnot being R48, the Label, the Administration Agent, R98, and / or CCare bound to the remainder of the molecule via CM2as defined herein, wherein preferably CM2equals or is comprised in a Spacer.

[0704] In yet other preferred embodiments, LAnot being R48, LBnot being R48, the Label, the Administration Agent, R98, and / or CCare bound to the remainder of the molecule via Cxas defined herein, wherein preferably Cxequals or is comprised in a Spacer. In preferred embodiments, moiety Cx, CM2and the said residue of R32are comprised in LAnot being R48, LBnot being R48, the Label, the Administration Agent, R98, and / or CC.

[0705] CM2

[0706] In preferred embodiments, CM2is selected from the group consisting of amine, amide, thioamide, aminooxy, carbamate, thiocarbamate, urea, thiourea, ether, sulfonamide, and sulfoncarbamate. In preferred embodiments CM2equals R10.

[0707] In preferred embodiments, CM2is:

[0708] wherein the dashed line denotes a bond to or towards LAnot being R48, LBnot being R48, the Label, the Administration Agent, SP, LC, R98, or CCand the wiggly line denotes a bond to the remaining part of the dienophile. In preferred embodiments the wiggly line denotes a bond to or towards LAnot being R48, LBnot being R48, the Label, the Administration Agent, SP, LC, R98, or CCand the dashed line denotes a bond to the remaining part of the dienophile.

[0709] With reference to above schemes with examples of CM2and Cx, in some embodiments it is preferred that when LAnot being R48, LBnot being R48, the Label, the Administration Agent, R98, or CCis a protein, such as an antibody, that the dashed line denotes a bond to or towards LAnot being R48, LBnot being R48, the Label, the Administration Agent, R98, or CC.

[0710] Intermediates for the preparation of compounds of Formula (1)

[0711] Preferred intermediates to prepare compounds of Formula (1) of the invention are listed below. Particularly preferred intermediates from the below are enantiomerically pure compounds A-F, in particular A, D, E, F. A person skilled in the art will understand that compounds E and F still need to be isomerized to E-cyclooctenes, after which the enantiomer with the axial OH can be separated from the enantiomer with the equatorial OH as described by Rossin et al Bioconj.Chem., 2016 27(7):1697-1706.

[0712]

[0713] A general synthesis method of a TCO trigger and its corresponding compound of Formula (l)s is shown directly below. The synthesis method is as reported in Rossin et al Nature Communications 2018, 9, 1484 and Rossin et al Bioconj.Chem., 2016 27(7):1697-1706 with the exception of the conversion of D to F, which now is conducted by mixing D with hydroxide solution in methanol, followed by evaporation and reaction with iodomethane. Please note that for sake of clarity only one of the two enantiomers of E-K is shown. A person skilled in the art will understand that the enantiomers can be separated at various stages in the synthesis using established chiral resolution methods to obtain

[0714] enantiomerically pure B, E, F, H, for example, such as chiral salts.

[0715]

[0716] wherein the wiggly line denotes the bond to the remainder of R48and the dashed line denotes the bond to the remainder of the molecule.

[0717] Cleaving Agent

[0718] The compound used to release one or more moieties R48from the structure of Formula (1) is herein referred to as“Cleaving Agent”.

[0719] In a preferred embodiment, the combination of the invention comprises a Cleaving Agent with the proviso that when at least one R48in Formula (1) is LB, then the Cleaving Agent does not comprise the Label of LB; with the proviso that when at least one R48in Formula (1) is LA, then the Cleaving Agent does not comprise the Administration Agent of LA;

[0720] wherein the Cleaving Agent is a diene.

[0721] In a preferred embodiment, the Cleaving Agent does not comprise a Label.

[0722] In a preferred embodiment, the Cleaving Agent does not comprise an Administration Agent.

[0723] In preferred embodiments wherein the Primary Target is an internalizing receptor and it is desired to selectively cleave the Label in blood and not at the Primary Target, the Cleaving Agent is preferentially designed to be cell impermeable. In said embodiment, wherein the Label is a chelate then the Cleaving Agent can be either internalizing or non-internalizing ,as the cleaved chelate cannot escape the target cell.

[0724] In preferred embodiments, wherein the Primary Target is a non

[0725] internalizing receptor and it is desired to cleave the Label in blood and not at the Primary Target, the Cleaving Agent is preferentially designed to extravasate poorly into tissues and rapidly clear, to minimize reaction at the Primary Target while achieving cleavage in blood.

[0726] In a preferred embodiment, the combination of the invention is a kit.

[0727] In some embodiments, preferably, the Cleaving Agent has a molecular weight of at most 150 kDa, when at least one R48in Formula (1) is LAthat does not comprise a Label; more preferably at most 70 kDa, most preferably at most 1 kDa.

[0728] In other embodiments, preferably, the Cleaving Agent has a molecular weight of at least 300 kDa, to minimize extravasation.

[0729] In preferred embodiments the Cleaving Agent is cell-impermeable, to further increase the selective cleavage of a compound of Formula (1) present in non-target sites ( e.g . blood).

[0730] In preferred embodiments, the properties of the Cleaving Agent (e.g. level of cell permeability and extravasation) are achieved by a suitably chosen R87group (vide infra), comprised in the Clearing Agent formulas below.

[0731] Preferably, the reaction of the Cleaving Agent with the Administration Agent present in a tissue of interest in vivo results in at least 20 % reduction of radioactivity, more preferably at least 40 %, more preferably at least 60 %, even more preferably at least 80 %.

[0732] In a preferred embodiment, the Cleaving Agent is a tetrazine. Tetrazines are dienes and are highly reactive towards dienophiles, especially the TCO constructs (vide supra). The diene of the Cleaving Agent is selected so as to be capable of reacting with the dienophile, e.g. the TCO, by undergoing a Diels- Alder cycloaddition followed by a retro Diels-Alder reaction, giving the IEDDA adduct. This intermediate adduct then releases the Construct-A.

[0733] Synthesis routes to tetrazines in general are readily available to the skilled person, based on standard knowledge in the art. References to tetrazine synthesis routes include for example Lions et al, J. Org. Chem., 1965, 30, 318- 319; Horwitz et al, J. Am. Chem. Soc., 1958, 80, 3155-3159; Hapiot et al, New J. Chem., 2004, 28, 387-392, Kaim et al, Z. Naturforsch., 1995, 50b, 123-127, Yang et al., Angew. Chem. 2012, 124, 5312 -5315; Mao et al., Angew. Chem. Int. Ed. 2019, 58, 1106-1109; Qu et al. Angew. Chem. Int. Ed. 2018, 57, 12057 -12061; Selvaraj et al., Tetrahedron Lett. 2014, 55, 4795-4797; Fan et al., Angew. Chem. Int. Ed. 2016, 55, 14046-14050.

[0734] Preferably, the Cleaving Agent is a tetrazine satisfying Formula (4) and preferably including pharmaceutically accepted salts thereof:

[0735] Formula (4) ; wherein each moiety Q1and Q2is independently selected from the group consisting of hydrogen, -F, -Cl, -Br, -I, -OR37, -N(R37)2, -SO3, -PO3-, -NO2, -CF3, -SR37,

[0736] S(=O)2N(R37)2, OC(=O)R37, SC(=O) R37, OC(=S)R37, SC(=S)R37, NR37C(=O)-R37, NR37C(=S)-R37, NR37C(=O)O-R37, NR37C(=S)O-R37, NR37C(=O)S-R37, NR37C(=S)S- R37, OC(=O)N(R37)2, SC(=O)N(R37)2, OC(=S)N(R37)2, SC(=S)N(R37)2,

[0737] NR37C(=O)N(R37)2, NR37C(=S)N(R37)2, C(=O)R37,C(=S)R37,C(=O)N(R37)2,

[0738] C(=S)N(R37)2, C(=O)O-R37, C(=O)S-R37, C(=S)O-R37, C(=S)S-R37, S(O)R37, - S(O) 2R37, NR37S(O)2R37, -ON(R37)2, -NR37OR37, alkyl groups, alkenyl groups, alkynyl groups, aryl groups, heteroaryl groups, cycloalkyl groups, cycloalkenyl groups, cycloalkynyl groups, (cyclo)alkyl(hetero)aryl groups,

[0739] (hetero)aryl(cyclo)alkyl, (cyclo)alkenyl(hetero)aryl groups,

[0740] (hetero)aryl(cyclo)alkenyl groups, (cyclo)alkynyl(hetero)aryl groups,

[0741] (hetero)aryl(cyclo)alkynyl groups, alkylcycloalkyl groups, and cycloalkylalkyl groups.

[0742] In Formula (4), the Q1and Q2groups not being H, -F, -Cl, -Br, -I, -OH, -

[0743] NH2, -SO3, -PO3, -NO2, -CF3, are optionally substituted, preferably with a moiety selected from the group consisting of -Cl, -F, -Br, -I, -OR37, -N(R37)2, -SO3R37, - PO3(R37)2, -PO4(R37)2, -NO2, -CF3, =O, =NR37, and -SR37, and optionally contain one or more heteroatoms selected from the group consisting of O, S, NR37, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized.

[0744] In Formula (4), the Q1and Q2groups are optionally bound to a polymer, a particle, a peptide, a peptoid, a dendrimer, a protein, an aptamer, a

[0745] carbohydrate, an oligonucleotide, an oligosaccharide, a lipid, a steroid, a liposome, a micelle, a Targeting Agent TT, a— (SP)D-R87, an albumin-binding moiety, and a chelating moiety; wherein D is 0 or 1.

[0746] In Formula (4), preferably, at least one of moieties Q1and Q2is not hydrogen.

[0747] In Formula (4), preferably each moiety Q1and Q2is independently selected from the group consisting of hydrogen, -F, -Cl, -Br, -I, -OR37, -N(R37)2, -SO3, -PO3 ,-NO2, -CF3, -SR37, S(=O)2N(R37)2, OC(=O)R37, SC(=O) R37, OC(=S)R37, SC(=S)R37, NR37C(=O)-R37, NR37C(=S)-R37, NR37C(=O)O-R37, NR37C(=S)O-R37, NR37C(=O)S- R37, NR37C(=S)S-R37, OC(=O)N(R37)2, SC(=O)N(R37)2, OC(=S)N(R37)2,

[0748] SC(=S)N(R37)2, NR37C(=O)N(R37)2, NR37C(=S)N(R37)2, C(=O)R37,C(=S)R37,

[0749] C(=O)N(R37)2, C(=S)N(R37)2, C(=O)O-R37, C(=O)S-R37, C(=S)O-R37, C(=S)S-R37, S(O)R37, -S(O)2R37, NR37S(O)2R37, -ON(R37)2, -NR37OR37, C-1C24alkyl groups, C2- C24alkenyl groups, C2-C24alkynyl groups, C6-C24aryl groups, C2-C24heteroaryl groups, C3-C24cycloalkyl groups, C5-C24cycloalkenyl groups, C12-C24cycloalkynyl groups, C3-C24(cyclo)alkyl(hetero)aryl groups, C3-C24(hetero)aryl(cyclo) alkyl, C4- C24(cyclo)alkenyl(hetero)aryl groups, C4-C24(hetero)aryl(cyclo) alkenyl groups, C4-C24(cyclo)alkynyl(hetero)aryl groups, C4-C24(hetero)aryl(cyclo)alkynyl groups, C4-C24alkylcycloalkyl groups, and C4-C24cycloalkylalkyl groups.

[0750] In preferred embodiments, the Q1and Q2groups not being hydrogen are not substituted.

[0751] In a preferred embodiment, Q1and Q2in Formula (4) are selected from the group of hydrogen, -F, -Cl, -Br, -I, -OR37, -N(R37)2, -SO3, -PO3-, -NO2, -CF3, -SR37, S(=O)2N(R37)2, OC(=O)R37, SC(=O) R37, OC(=S)R37, SC(=S)R37, NR37C(=O)-R37, NR37C(=S)-R37, NR37C(=O)O-R37, NR37C(=S)O-R37, NR37C(=O)S-R37, NR37C(=S)S- R37, OC(=O)N(R37)2, SC(=O)N(R37)2, OC(=S)N(R37)2, SC(=S)N(R37)2,

[0752] NR37C(=O)N(R37)2, NR37C(=S)N(R37)2, C(=O)R37,C(=S)R37,C(=O)N(R37)2,

[0753] C(=S)N(R37)2, C(=O)O-R37, C(=O)S-R37, C(=S)O-R37, C(=S)S-R37, S(O)R37, - S(O) 2R37, NR37S(O)2R37, -ON(R37)2, -NR37OR37, C1-C8alkyl groups, C2-C8alkenyl groups, C2-C8alkynyl groups, C6-C12aryl groups, C2-C12heteroaryl groups, C3-C8cycloalkyl groups, C5-C8cycloalkenyl groups, C3-C12alkyl(hetero)aryl groups, C3- C12(hetero)arylalkyl groups, C4-C12alkylcycloalkyl groups, C4-C12cycloalkylalkyl groups, C5-C12cycloalkyl(hetero)aryl groups and C5-C12(hetero)arylcycloalkyl groups.

[0754] In a preferred embodiment, Q1and Q2in Formula (4) are selected from the group of hydrogen, -F, -Cl, -Br, -I, -OR37, -N(R37)2, -SO3, -PO3-, -NO2, -CF3, -SR37, S(=O)2N(R37)2, OC(=O)R37, SC(=O) R37, OC(=S)R37, SC(=S)R37, NR37C(=O)-R37, NR37C(=S)-R37, NR37C(=O)O-R37, NR37C(=S)O-R37, NR37C(=O)S-R37, NR37C(=S)S- R37, OC(=O)N(R37)2, SC(=O)N(R37)2, OC(=S)N(R37)2, SC(=S)N(R37)2,

[0755] NR37C(=O)N(R37)2, NR37C(=S)N(R37)2, C(=O)R37,C(=S)R37,C(=O)N(R37)2,

[0756] C(=S)N(R37)2, C(=O)O-R37, C(=O)S-R37, C(=S)O-R37, C(=S)S-R37, S(O)R37, - S(O) 2R37, NR37S(O)2R37, -ON(R37)2,-NR37OR37, C-C1 4alkyl groups, C2-C4alkenyl groups, C2-C4alkynyl groups, C6-C8aryl groups, C2-C8heteroaryl groups, C3-C6cycloalkyl groups, C5-C6cycloalkenyl groups, C3-C10alkyl(hetero)aryl groups, C3- C10(hetero)arylalkyl groups, C4-C10alkylcycloalkyl groups, C4-C10cycloalkylalkyl groups, C5-C10cycloalkyl(hetero)aryl groups and C5-C10(hetero)arylcycloalkyl groups.

[0757] In a preferred embodiment, Q1and Q2in Formula (4) are selected from the group of hydrogen, phenyl, 2-pyridyl, 3-pyridyl, 4-pyridyl, 2,6-pyrimidyl, 2,5- pyrimidyl, 3,5-pyrmidyl, and 2,4-pyrimidyl; and Q1and Q2not being hydrogen are optionally substituted with a moiety selected from the group consisting of -F, -Cl, -Br, -I, -OR37, -N(R37)2, -SO3, -PO3-, -NO2, -CF3, -SR37, S(=O)2N(R37)2,

[0758] OC(=O)R37, SC(=O) R37, OC(=S)R37, SC(=S)R37, NR37C(=O)-R37, NR37C(=S)-R37, NR37C(=O)O-R37, NR37C(=S)O-R37, NR37C(=O)S-R37, NR37C(=S)S-R37,

[0759] OC(=O)N(R37)2, SC(=O)N(R37)2, OC(=S)N(R37)2, SC(=S)N(R37)2, NR37C(=O)N(R37)2, NR37C(=S)N(R37)2, C(=O)R37,C(=S)R37,C(=O)N(R37)2, C(=S)N(R37)2, C(=O)O-R37, C(=O)S-R37, C(=S)O-R37, C(=S)S-R37, S(O)R37, -S(O)2R37, NR37S(O)2R37, -ON(R37)2,- NR37OR37, C1-C24alkyl groups, C2-C24alkenyl groups, C2-C24alkynyl groups, C6- C24aryl groups, C2-C24heteroaryl groups, C3-C24cycloalkyl groups, C5-C24cycloalkenyl groups, C12-C24cycloalkynyl groups, C3-C24(cyclo)alkyl(hetero)aryl groups, C3-C24(hetero)aryl(cyclo)alkyl, C4-C24(cyclo)alkenyl(hetero)aryl groups, C4-C24(hetero) aryl (cyclo) alkenyl groups, C4-C24(cyclo)alkynyl(hetero)aryl groups, C4-C24(hetero) aryl (cyclo) alkynyl groups, C4-C24alkylcycloalkyl groups, and C4- C24cycloalkylalkyl groups; preferably with a moiety selected from the group consisting of -F, -Cl, -Br, -I, -OR37, -N(R37)2, -SO3, -PO3, -NO2, -CF3, -SR37, S(=O)2N(R37)2, OC(=O)R37, SC(=O) R37, OC(=S)R37, SC(=S)R37, NR37C(=O)-R37, NR37C(=S)-R37, NR37C(=O)O-R37, NR37C(=S)O-R37, NR37C(=O)S-R37, NR37C(=S)S- R37, OC(=O)N(R37)2, SC(=O)N(R37)2, OC(=S)N(R37)2, SC(=S)N(R37)2,

[0760] NR37C(=O)N(R37)2, NR37C(=S)N(R37)2, C(=O)R37,C(=S)R37,C(=O)N(R37)2,

[0761] C(=S)N(R37)2, C(=O)O-R37, C(=O)S-R37, C(=S)O-R37, C(=S)S-R37, S(O)R37, - S(O)2R37, NR37S(O)2R37, -ON(R37)2,-NR37OR37, C1-C8alkyl groups, C2-C8alkenyl groups, C2-C8alkynyl groups, C6-C12aryl groups, C2-C12heteroaryl groups, C3-C8cycloalkyl groups, C5-C8cycloalkenyl groups, C3-C12alkyl(hetero)aryl groups, C3- C12(hetero)arylalkyl groups, C4-C12alkylcycloalkyl groups, C4-C12cycloalkylalkyl groups, C5-C12cycloalkyl(hetero)aryl groups, and C5-C12(hetero)arylcycloalkyl groups; more preferably with a moiety selected from the group consisting of -F, - Cl, -Br, -I, -OR37, -N(R37)2, -SO3, -PO3-, -NO2, -CF3, -SR37, S(=O)2N(R37)2,

[0762] OC(=O)R37, SC(=O) R37, OC(=S)R37, SC(=S)R37, NR37C(=O)-R37, NR37C(=S)-R37, NR37C(=O)O-R37, NR37C(=S)O-R37, NR37C(=O)S-R37, NR37C(=S)S-R37,

[0763] OC(=O)N(R37)2, SC(=O)N(R37)2, OC(=S)N(R37)2, SC(=S)N(R37)2, NR37C(=O)N(R37)2, NR37C(=S)N(R37)2, C(=O)R37,C(=S)R37,C(=O)N(R37)2, C(=S)N(R37)2, C(=O)O-R37, C(=O)S-R37, C(=S)O-R37, C(=S)S-R37, S(O)R37, -S(O)2R37, NR37S(O)2R37, -ON(R37)2,- NR37OR37, C1-C4alkyl groups, C2-C4alkenyl groups, C2-C4alkynyl groups, C6-C8aryl groups, C2-C8heteroaryl groups, C3-C6cycloalkyl groups, C5-C6cycloalkenyl groups, C3-C10alkyl(hetero)aryl groups, C3-C10(hetero)arylalkyl groups, C4-C10alkylcycloalkyl groups, C4-C10cycloalkylalkyl groups, C5-C10

[0764] cycloalkyl(hetero)aryl groups, and C5-C10(hetero)arylcycloalkyl groups.

[0765] In a preferred embodiment, in Formula (4):

[0766] (a) Q1and Q2are selected from the group consisting of 2-pyridyl, 3-pyridyl, and 4- pyridyl;

[0767] (b) Q1is selected from the group consisting of 2,6-pyrimidyl, 2,5-pyrimidyl, 3,5- pyrmidyl, and 2,4-pyrimidyl; and Q2is (hetero)alkyl; or

[0768] (c) Q1is phenyl and Q2is hydrogen;

[0769] (d) Q1is alkyl and Q2is alkyl;

[0770] (e) Q1is phenyl and Q2is alkyl;

[0771] (f) Q1is phenyl and Q2is phenyl;

[0772] and in (a)-(f) all Q1and Q2not being hydrogen are optionally substituted as defined in the previous paragraph.

[0773] In a preferred embodiment, in Formula (4) the alkyl is a C1-C24alkyl group, preferably a C1-C12alkyl group, more preferably a C1-C6(hetero)alkyl group.

[0774] In a preferred embodiment, in Formula (4) the (hetero)aryl is a C6-C24aryl group, preferably a C6-C12aryl, more preferably a phenyl.

[0775] In a preferred embodiment, in Formula (4) the (hetero)aryl is a C2-C24heteroaryl, preferably a C2-C12heteroaryl, more preferably a C2-C5heteroaryl.

[0776] In a preferred embodiment, in Formula (4) the alkenyl is a C2-C24alkenyl, preferably a C2-C12alkenyl, more preferably a C2-C6alkenyl.

[0777] In a preferred embodiment, in Formula (4) the alkynyl is a C2-C24alkynyl, preferably a C2-C12alkynyl, more preferably a C2-C6alkynyl.

[0778] In a preferred embodiment, in Formula (4) the cycloalkyl is a C3-C24cycloalkyl, preferably a C3-C12cycloalkyl, more preferably a C3-C6cycloalkyl.

[0779] In a preferred embodiment, in Formula (4) the cycloalkenyl, C5-C24cycloalkenyl groups, preferably a C5-C12cycloalkenyl, more preferably a C5-C6cycloalkenyl.

[0780] In a preferred embodiment, in Formula (4) the cycloalkynyl is a C6-C24cycloalkynyl, preferably a C8-C12cycloalkynyl, more preferably a C8cycloalkyl.

[0781] In preferred embodiments, the Cleaving Agent can be a multimeric compound, comprising a plurality of dienes as defined herein. These multimeric compounds include but are not limited to biomolecules, proteins, peptides, peptoids, polymers, dendrimers, liposomes, micelles, particles, gels, polymer particles, or other polymeric constructs.

[0782] Preferred tetrazines

[0783] Formula (4a)

[0784] Preferred tetrazines are in accordance with Formula (4a), and preferably include pharmaceutically accepted salts thereof:

[0785] Formula (4a)

[0786] , wherein each moiety Q1and Q2is independently selected from the group consisting of hydrogen and moieties according to Formula (5):

[0787] Formula (5)

[0788] , wherein the dashed line indicates a bond to the remainder of the molecule, and wherein R10, R11, and R12are as defined herein.

[0789] As will be understood herein, in relation to Formula (5), the dashed line may indicate a bond to a tetrazine group of Formula (4a), another moiety according to Formula (5), or to the remainder of the compound according to Formulae (6)-(13) as defined below.

[0790] In a preferred embodiment, each f in Formula (5) is an integer

[0791] independently selected from a range of from 0 to 24, preferably in a range of from 1 to 12, more preferably in a range of from 2 to 6, even more preferably from 1 to 3. In a preferred embodiment, f is 1. In other preferred embodiments f is an integer in the range from 12 to 24.

[0792] In a preferred embodiment, in Formula (5) g is an integer in a range of from 0 to 12, preferably in a range of from 1 to 6, more preferably in a range of from 2 to 4.

[0793] In a preferred embodiment, in Formula (5) each h is independently 0 or 1. In a preferred embodiment, g is 0, and f is 1. In a preferred embodiment, g is 1, and f is 1.

[0794] In case the compound according to the invention comprises more than one moiety satisfying Formula (5), each g, h, and f is independently selected.

[0795] In a preferred embodiment, the moiety according to Formula (5) is optionally substituted with another independently selected moiety according to Formula (5). In another preferred embodiment, the moiety according to Formula (5) is not substituted with another independently selected moiety according to Formula (5). In a preferred embodiment, the moiety according to Formula (5) is a R87, as defined further below.

[0796] In a preferred embodiment, the moiety according to Formula (5) satisfies molecules from Group RMshown further below

[0797] It is preferred that at least one of moieties Q1and Q2in Formula (4a) is not hydrogen.

[0798] In preferred embodiments, Q1in Formula (4a) is selected from the group consisting of C6-C24aryl, and C2-C24heteroaryl, and is optionally further substituted with a moiety according to Formula (5), preferably not more than one moiety according to Formula (5).

[0799] In preferred embodiments, Q1in Formula (4a) is selected from the group consisting of C6-C24aryl, and C2-C24heteroaryl, and is optionally further substituted with a moiety according to Formula (5), preferably not more than one moiety according to Formula (5), and Q2in Formula (4a) is selected from the group consisting of C6-C24aryl, and C2-C24heteroaryl, and is optionally further substituted with a moiety according to Formula (5), preferably not more than one moiety according to Formula (5).

[0800] In preferred embodiments, Q1in Formula (4a) is selected from the group consisting of C6aryl, and C3-C5heteroaryl, and is optionally further substituted with at least one moiety according to Formula (5), preferably not more than one moiety according to Formula (5). Herein, preferred heteroaryls are 2-pyridyl, 3- pyridyl, 4-pyridyl, 2,6-pyrimidyl, 3,5-pyrimidyl, 2,5-pyrimidyl, 2,4-pyrimidyl, 2,4 imidazyl, 2,5 imidazyl, phenyl, 2,3-pyrazyl, 3,4-pyrazyl, oxazol, isoxazol, thiazol, oxazoline, 2-pyrryl, 3-pyrryl, 2-thiophene, and 3-thiophene.

[0801] In preferred embodiments, Q1in Formula (4a) is C3-C5heteroaryl, and is optionally further substituted with at least one moiety according to Formula (5), preferably not more than one moiety according to Formula (5), and Q2is C3-C5heteroaryl, and is optionally further substituted with a moiety according to Formula (5), preferably not more than one moiety according to Formula (5).

[0802] Herein, preferred heteroaryls are 2-pyridyl, 3-pyridyl, 4-pyridyl, 2,6-pyrimidyl, 3,5-pyrimidyl, 2,5-pyrimidyl, 2,4-pyrimidyl, 2,4 imidazyl, 2,5 imidazyl, phenyl, 2,3-pyrazyl, 3,4-pyrazyl, oxazol, isoxazol, thiazol, oxazoline, 2-pyrryl, 3-pyrryl, 2- thiophene, and 3-thiophene.

[0803] In preferred embodiments, Q1in Formula (4a) is C3-C5heteroaryl, and is optionally further substituted with at least one moiety according to Formula (5), preferably not more than one moiety according to Formula (5), and Q2is H.

[0804] In preferred embodiments, Q1in Formula (4a) is a phenyl ring, and is optionally further substituted with at least one moiety according to Formula (5), preferably not more than one moiety according to Formula (5), and Q2is -H.

[0805] In preferred embodiments, Q1in Formula (4a) is a phenyl ring, and is optionally further substituted with at least one moiety according to Formula (5), preferably not more than one moiety according to Formula (5), and Q2is a phenyl ring, and is optionally further substituted with at least one moiety according to Formula (5), preferably not more than one moiety according to Formula (5).

[0806] In preferred embodiments, Q1in Formula (4a) is a phenyl ring, and is optionally further substituted with at least one moiety according to Formula (5), preferably not more than one moiety according to Formula (5), and Q2is selected from the group consisting of C6aryl, and C3-5 heteroaryl, and is optionally further substituted with at least one moiety according to Formula (5), preferably not more than one moiety according to Formula (5).

[0807] In preferred embodiments, Q1in Formula (4a) is C1-C12alkyl, and is optionally further substituted with at least one moiety according to Formula (5), preferably not more than one moiety according to Formula (5), and Q2selected from the group consisting of C6aryl, and C3-5 heteroaryl, and is optionally further substituted with at least one moiety according to Formula (5), preferably not more than one moiety according to Formula (5).

[0808] In preferred embodiments, Q1in Formula (4a) is C1-C12alkyl, and is optionally further substituted with at least one moiety according to Formula (5), preferably not more than one moiety according to Formula (5), and Q2in Formula (4a) is C1-C12alkyl, and is optionally further substituted with at least one moiety according to Formula (5), preferably not more than one moiety according to Formula (5).

[0809] In preferred embodiments Q2equals Q1. R10

[0810] In preferred embodiments, each R10is independently selected from the group consisting of -O-, -S-, -SS-, -NR4-, -N=N-, -C(O)-, -C(O)NR4-, -OC(O)-, -C(O)O-, -OC(O)O-, -OC(O)NR4-, -NR4C(O)-, -NR4C(O)O-, -NR4C(O)NR4-, -SC(O)-, -C(O)S-, -SC(O)O-, -OC(O)S-, -SC(O)NR4-, -NR4C(O)S-, -S(O)-, -S(O)2-, -OS(O)2-, -S(O2)O-, -OS(O)2O-, -OS(O)2NR4-, -NR4S(O)2O-, -C(O)NR4S(O)2NR4-, -OC(O)NR4S(O)2NR4-, -OS(O)-, -OS(O)O-, -OS(O)NR4-, -ONR4C(O)-, -ONR4C(O)O-, -ONR4C(O)NR4-, -NR4OC(O)-, -NR4OC(O)O-, -NR4OC(O)NR4-, -ONR4C(S)-, -ONR4C(S)O-,

[0811] -ONR4C(S)NR4-, -NR4OC(S)-, -NR4OC(S)O-, -NR4OC(S)NR4-, -OC(S)-, -C(S)O-, -OC(S)O-, -OC(S)NR4-, -NR4C(S)-, -NR4C(S)O-, -SS(O)2-, -S(O)2S-, -OS(O2)S-, -SS(O)2O-, -NR4OS(O)-, -NR4OS(O)O-, -NR4OS(O)NR4-, -NR4OS(O)2-,

[0812] -NR4OS(O)2O-, -NR4OS(O)2NR4-, -ONR4S(O)-, -ONR4S(O)O-, -ONR4S(O)NR4-, -ONR4S(O)2O-, -ONR4S(O)2NR4-, -ONR4S(O)2-, -OP(O)(R4)2-, -SP(O)(R4)2-,

[0813] -NR4P(O)(R4)2-, and combinations thereof, wherein R4is defined as described herein.

[0814] In preferred embodiments, each R10is independently selected from the group consisting of -O-, -S-, -SS-, -NR4-, -N=N-, -C(O)-, -C(O)NR4-, -OC(O)-, - C(O)O-, -OC(O)NR4-, -NR4C(O)-, -NR4C(O)O-, -NR4C(O)NR4-, -SC(O)-, -C(O)S-, - SC(O)O-, -OC(O)S-, -SC(O)NR4-, -NR4C(O)S-, -SCO)-, -S(O)2-, -C(O)NR4S(O)2NR4-, -OC(O)NR4S(O)2NR4-, -OC(S)-, -C(S)O-, -OC(S)O-, -OC(S)NR4-, -NR4C(S)-, - NR4C(S)O-, and -SS(O)2-.

[0815] R11

[0816] In preferred embodiments, each R11is independently selected from the group consisting of C1-C24alkylene groups, C2-C24alkenylene groups, C2-C24alkynylene groups, C6-C24arylene, C2-C24heteroarylene, C3-C24cycloalkylene groups, C5-C24cycloalkenylene groups, and C12-C24cycloalkynylene groups, which are optionally further substituted with one or more substituents selected from the group consisting of -Cl, -F, -Br, -I, -OH, -NH2, -SO3H, -PO3H,-PO4H2, -NO2, -CF3, =O, =NR36, -SR36, C1-C24alkyl groups, C2-C24alkenyl groups, C2-C24alkynyl groups, C6-C24aryl groups, C2-C24heteroaryl groups, C3-C24cycloalkyl groups, C5-C24 cycloalkenyl groups, C12-C24cycloalkynyl groups, C3-C24alkyl(hetero)aryl groups, C3-C24(hetero)arylalkyl groups, C4-C24(hetero)arylalkenyl groups, C4-C24

[0817] (hetero)arylalkynyl groups, C4-C24alkenyl(hetero)aryl groups, C4-C24

[0818] alky nyl(hetero) aryl groups, C4-C24alkylcycloalkyl groups, C6-C24

[0819] alkylcycloalkenyl groups, C13-C24alkylcycloalkynyl groups, C4-C24cycloalkylalkyl groups, C6-C24cycloalkenylalkyl groups, C13-C24cycloalkynylalkyl groups, C5-C24alkenylcycloalkyl groups, C7-C24alkenylcycloalkenyl groups, C14-C24

[0820] alkenylcycloalkynyl groups, C5-C24cycloalkylalkenyl groups, C7-C24

[0821] cycloalkenylalkenyl groups, C14-C24cycloalkynylalkenyl groups, C5-C24

[0822] alkynylcycloalkyl groups, C7-C24alkynylcycloalkenyl groups, C14-C24

[0823] alkynylcycloalkynyl groups, C5-C24cycloalkylalkynyl groups, C7-C24

[0824] cycloalkenylalkynyl groupsC,14-C24cycloalkynylalkynyl groups, C5-C24

[0825] cycloalkyl(hetero)aryl groups, C7-C24cycloalkenyl(hetero)aryl groups, C14-C24cycloalkynyl(hetero)aryl groups, C5-C24(hetero)arylcycloalkyl groups, C7-C24(hetero)arylcycloalkenyl groups, and C14-C24(hetero)arylcycloalkynyl groups, wherein the substituents optionally contain one or more heteroatoms selected from the group consisting of O, S, NR36, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized;

[0826] and wherein preferably the alkylene groups, alkenylene groups, alkynylene groups, cycloalkylene groups, cycloalkenylene groups, and cycloalkynylene groups optionally contain one or more heteroatoms selected from the group consisting of O, S, NR36, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized.

[0827] In preferred embodiments, each R11is independently selected from the group consisting of C1-C12alkylene groups, C2-C12alkenylene groups, C2-C12alkynylene groups, C6-C12arylene, C2-C12heteroarylene, C3-C12cycloalkylene groups, C5-C12cycloalkenylene groups, and C12cycloalkynylene groups;

[0828] and wherein preferably the alkylene groups, alkenylene groups, alkynylene groups, cycloalkylene groups, cycloalkenylene groups, and cycloalkynylene groups optionally contain one or more heteroatoms selected from the group consisting of O, S, NR36, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized. In preferred embodiments, each R11is independently selected from the group consisting of C1-C6alkylene groups, C2-C6alkenylene groups, C2-C6alkynylene groups, C6-C6arylene, C2-C6heteroarylene, C3-C6cycloalkylene groups, and C5-C6cycloalkenylene groups;

[0829] and wherein preferably the alkylene groups, alkenylene groups, alkynylene groups, cycloalkylene groups, cycloalkenylene groups, and cycloalkynylene groups optionally contain one or more heteroatoms selected from the group consisting of O, S, NR36, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized.

[0830] In preferred embodiments, the R11groups are optionally further

[0831] substituted with one or more substituents selected from the group consisting of - Cl, -F, -Br, -I, -OH, -NH2, -SO3H, -PO3H, -PO4H2, -NO2, -CF3, =O, =NR36, -SR36, C1-C12alkyl groups, C2-C12alkenyl groups, C2-C12alkynyl groups, C6-C12aryl groups, C2-C12heteroaryl groups, C3-C12cycloalkyl groups, C5-C12cycloalkenyl groups, C12cycloalkynyl groups, C3-C12alkyl(hetero)aryl groups, C3-C12

[0832] (hetero)arylalkyl groups, C4-C12(hetero)arylalkenyl groups, C4-C12

[0833] (hetero)arylalkynyl groups, C4-C12alkenyl(hetero)aryl groups, C4-C12

[0834] alky nyl(hetero) aryl groups, C4-C12alkylcycloalkyl groups, C6-C12

[0835] alkylcycloalkenyl groups, C13-C18alkylcycloalkynyl groups, C4-C12cycloalkylalkyl groups, C6-C12cycloalkenylalkyl groups, C13-C18cycloalkynylalkyl groups, C5-C12alkenylcycloalkyl groups, C7-C12alkenylcycloalkenyl groups, C14-C16

[0836] alkenylcycloalkynyl groups, C5-C12cycloalkylalkenyl groups, C7-C12

[0837] cycloalkenylalkenyl groups, C14-C16cycloalkynylalkenyl groups, C5-C12

[0838] alkynylcycloalkyl groups, C7-C12alkynylcycloalkenyl groups, C14-C16

[0839] alkynylcycloalkynyl groups, C5-C12cycloalkylalkynyl groups, C7-C12

[0840] cycloalkenylalkynyl groups, C14-C16cycloalkynylalkynyl groups, C5-C12

[0841] cycloalkyl(hetero)aryl groups, C7-C12cycloalkenyl(hetero)aryl groups, C14-C16cycloalkynyl(hetero)aryl groups, C5-C12(hetero)arylcycloalkyl groups, C7-C12(hetero)arylcycloalkenyl groups, and C14-C16(hetero)arylcycloalkynyl groups, wherein the substituents optionally contain one or more heteroatoms selected from the group consisting of O, S, NR36, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized. In preferred embodiments, the R11groups are optionally further substituted with one or more substituents selected from the group consisting of - Cl, -F, -Br, -I, -OH, -NH2, -SO3H, -PO3H, -PO4H2, -NO2, -CF3, =O, =NR36, -SR36, C1-C6alkyl groups, C2-C6alkenyl groups, C2-C6alkynyl groups, C6aryl groups, C2-C6heteroaryl groups, C3-C6cycloalkyl groups, C5-C6cycloalkenyl groups, C3- C6alkyl(hetero)aryl groups, C3-C6(hetero)arylalkyl groups, C4-C6

[0842] (hetero)arylalkenyl groups, C4-C6(hetero)arylalkynyl groups, C4-C6

[0843] alkenyl(hetero)aryl groups, C4-C6alkynyl(hetero)aryl groups, C4-C6

[0844] alkylcycloalkyl groups, Ce alkylcycloalkenyl groups, C4-C6cycloalkylalkyl groups, C6cycloalkenylalkyl groups, C5-C6alkenylcycloalkyl groups, C7

[0845] alkenylcycloalkenyl groups, C5-C6cycloalkylalkenyl groups, C7

[0846] cycloalkenylalkenyl groups, C5-C6alkynylcycloalkyl groups, C7

[0847] alkynylcycloalkenyl groups, C5-C6cycloalkylalkynyl groups, C5-C6

[0848] cycloalkyl(hetero)aryl groups, and C5-C6(hetero)arylcycloalkyl groups, wherein the substituents optionally contain one or more heteroatoms selected from the group consisting of O, S, NR36, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized.

[0849] In preferred embodiments, the R11groups are optionally further

[0850] substituted with one or more substituents selected from the group consisting of - Cl, -F, -Br, -I, -OH, -NH2, -SO3H, -PO3H, -PO4H2, -NO2, -CF3, =O, =NR36, -SR36, C1-C6alkyl groups, C2-C6alkenyl groups, C2-C6alkynyl groups, C6aryl groups, C2-C6heteroaryl groups, C3-C6cycloalkyl groups, C5-C6cycloalkenyl groups, C3- C7alkyl(hetero)aryl groups, C3-C7(hetero)arylalkyl groups, C4-C8

[0851] (hetero)arylalkenyl groups, C4-C8(hetero)arylalkynyl groups, C4-C8

[0852] alkenyl(hetero)aryl groups, C4-C8alkynyl(hetero)aryl groups, C4-C6

[0853] alkylcycloalkyl groups, C6-C7alkylcycloalkenyl groups, C4-C6cycloalkylalkyl groups, C6-C7cycloalkenylalkyl groups, C5-C6alkenylcycloalkyl groups, C7-C8alkenylcycloalkenyl groups, C5-C6cycloalkylalkenyl groups, C7-C8

[0854] cycloalkenylalkenyl groups, C5-C6alkynylcycloalkyl groups, C7-C8

[0855] alkynylcycloalkenyl groups, C5-C6cycloalkylalkynyl groups, C5-C9

[0856] cycloalkyl(hetero)aryl groups, and C5-C6(hetero)arylcycloalkyl groups, wherein the substituents optionally contain one or more heteroatoms selected from the group consisting of O, S, NR36, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized.

[0857] It is preferred that when f > 2, that R11is independently selected from the group consisting of C1-C6alkylene groups, C2-C6alkenylene groups, C2-C6alkynylene groups, C6-C6arylene, C2-C6heteroarylene, C3-C6cycloalkylene groups, and C5-C6cycloalkenylene groups; and wherein preferably the alkylene groups, alkenylene groups, alkynylene groups, cycloalkylene groups,

[0858] cycloalkenylene groups, and cycloalkynylene groups optionally contain one or more heteroatoms selected from the group consisting of O, S, NR36, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized.

[0859] In a preferred embodiment, the R11substituents do not contain heteroatoms.

[0860] In a preferred embodiment, the R11groups are not substituted.

[0861] In another preferred embodiment, the R11groups do not contain heteroatoms.

[0862] R12

[0863] R12is selected from the group consisting of -H, -OH, -NH2, -N3, -Cl, -Br, -F, -I, a polymer, a particle, a peptide, a peptoid, a dendrimer, a protein, a biomolecule, a carbohydrate, an oligonucleotide, an oligosaccharide, a lipid, a liposome, a micelle, an imaging moiety, a Targeting Agent TT, a R87, an albumin-binding moiety, and a chelating moiety.

[0864] Non-limiting examples of chelating moieties for use in R12are DTPA (diethylenetriaminepentaacetic acid),

[0865] DOTA (1,4,7,10- tetraazacyclododecane-N,N',N",N"-tetraacetic acid),

[0866] NOTA (l,4,7-triazacyclononane-N,N',N"-triacetic acid),

[0867] TETA (1,4,8, ll-tetraazacyclotetradecane-N,N',N",N'-tetraacetic acid),

[0868] OTTA (Nl-(p-isothiocyanatobenzyl)-diethylenetriamine-Ni,N2,N3,N3-tetraacetic acid), deferoxamine or DFO (N'-[5-[[4-[[5-(acetylhydroxyamino)pentyl]amino]-l,4- dioxobutyl] hydroxy amino] pentyl] -N- (5 - aminopentyl) - N -hy droxybutanediamide) or HYNIC (hydrazino nicotinamide).

[0869] In a preferred embodiment, when R12is a polymer, a particle, a peptide, a peptoid, a dendrimer, a protein, a biomolecule, an oligonucleotide, an oligosaccharide, a lipid, a liposome, a micelle, a Targeting Agent TT, or a R87, then f is at most 2, preferably at most 1.

[0870] Formulae (6) ( 7 ) (8) ( 9 ) (10) (11 ) (12) and (13)

[0871] In preferred embodiments of the invention the tetrazine is in accordance with any one of the Formulae (6), (7), (8), (9), (10), (11), (12), or (13):

[0872]

[0873] wherein each moiety Q, Q1, Q2, Q3, and Q4is independently selected from the group consisting of hydrogen and moieties according to Formula (5) as defined herein; and wherein R1, R2, and R3are as defined herein.

[0874] In preferred embodiments, in the tetrazines according to any one of Formulae (6), (7), (8), (9), (10), (11), (12), and (13), at most one moiety selected from the group consisting of Q, Q1, Q2, Q3, and Q4is hydrogen.

[0875] In preferred embodiments, in the tetrazines according to any one of Formulae (7), (8), (9), (10), (11), (12), and (13), at most two moieties selected from the group consisting of Q, Q1, Q2, Q3, and Q4are hydrogen.

[0876] In preferred embodiments, in the tetrazines according to any one of Formulae (7), (8), (9), (10), (11), (12), and (13), at most three moieties selected from the group consisting of Q, Q1, Q2, Q3, and Q4are hydrogen.

[0877] In preferred embodiments, in the tetrazines according to any one of Formulae (7), (8), (9), (10), (11), (12), and (13), all moieties selected from the group consisting of Q, Q1, Q2, Q3, and Q4are hydrogen. In preferred embodiments, in the tetrazines according to any one of

[0878] Formulae (7), (8), (9), (10), (11), (12), and (13), at most one moiety selected from the group consisting of Q, Q1, Q2, Q3, and Q4is not hydrogen.

[0879] In preferred embodiments, in the tetrazines according to any one of

[0880] Formulae (7), (8), (9), (10), (11), (12), and (13), at most two moieties selected from the group consisting of Q, Q1, Q2, Q3, and Q4is not hydrogen.

[0881] Molecular weight

[0882] Preferably, for all compounds disclosed herein comprising a group Q, Q1, Q2, Q3, Q4or -(CH2)y-((R1)p-R2)n-(R1)p-R3, at least one of these groups has a molecular weight in a range of from 100 Da to 3000 Da. Preferably, at least one of these groups has a molecular weight in a range of from 100 Da to 2000 Da. More preferably, at least one of these groups has a molecular weight in a range of from 100 Da to 1500 Da, even more preferably in a range of from 150 Da to 1500 Da. Even more preferably still, at least one of these groups has a molecular weight in a range of from 150 Da to 1000 Da, most preferably in a range of from 200 Da to 1000 Da.

[0883] Preferably, for all compounds disclosed herein, comprising a group Q, Q1, Q2 , Q3 , Q4 or -(CH2)y-((R1)p-R2)n-(Ri)p-R3, none of these groups has a molecular weight of more than 3000 Da, in particular in the case the Clearing Agent needs to efficiently extravasate into tissues.

[0884] GrOUP -(CH2) -((R1)p-R2)n-(R1)p-R3

[0885] In preferred embodiments, y is an integer in a range of from 1 to 12, preferably from 1 to 10, more preferably from 1 to 8, even more preferably from 2 to 6, most preferably from 2 to 4. In preferred embodiments, y is at least 2, preferably y is at least 3. In preferred embodiments, p is 0 or 1, wherein each p is independently selected. In preferred embodiments, each n is an integer independently selected from a range of from 0 to 24, preferably from 1 to 12, more preferably from 1 to 6, even more preferably from 1 to 3, most preferably n is 0 or 1. In preferred embodiments n is preferably an integer from 12 to 24. In preferred embodiments, n is 1. In preferred embodiments, the entire group -((R1)p-R2)n-(R1)p-R3has a molecular weight in a range of from 100 Da to 3000 Da. Preferably, the entire group -((R1)p-R2)n-(R1)p-R3has a molecular weight in a range of from 100 Da to 2000 Da. More preferably, the entire group -((R1)p-R2)n-(R1)P-R3has a molecular weight in a range of from 100 Da to 1500 Da, even more preferably in a range of from 150 Da to 1500 Da. Even more preferably still, the entire group -((R1)p-R2)n- (RI)P-R3has a molecular weight in a range of from 150 Da to 1000 Da, most preferably in a range of from 200 Da to 1000 Da.

[0886] It is preferred that when n > 2, that R2is independently selected from the group consisting of C1-C6alkylene groups, C2-C6alkenylene groups, C2-C6alkynylene groups, C6-C6arylene, C2-C6heteroarylene, C3-C6cycloalkylene groups, and C5-C6cycloalkenylene groups; and wherein preferably the alkylene groups, alkenylene groups, alkynylene groups, cycloalkylene groups,

[0887] cycloalkenylene groups, and cycloalkynylene groups optionally contain one or more heteroatoms selected from the group consisting of O, S, NR36, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized.

[0888] In preferred embodiments, the entire group -((R1)p-R2)n-(R1)p-R3satisfies molecules from Group RMshown below. RM:

[0889] , wherein the wiggly line denotes a bond to a tetrazine group as disclosed herein or to a group R1or R2.

[0890] In preferred embodiments, the group -((Ri)p-R2)n-(Ri)P-R3 satisfies molecules from Group RM, wherein it is understood that when n is more than 1, -((R1)p-R2)n-(R1)p-R3may be preceded by a group -((R1)p-R2) - so as to form a group -((Ri)p-R2)-((Ri)P-R2)n-i-(Ri)P-R3. It is understood that this follows from the definition of how to write out the repeating units, i.e. -((R1)p-R2)2- would first be written as - (R1)p-R2- (R1)p-R2- before Ri, p, and R2are independently selected.

[0891] R1R2. and R3

[0892] R1is as defined for R10. R2is as defined for R11. R3is as defined for R12.

[0893] R4

[0894] Preferably, each R4is independently selected from the group consisting of hydrogenC,1-C24alkyl groups, C2-C24alkenyl groups, C2-C24alkynyl groups, C6- C24aryl, C2-C24heteroaryl, C3-C24cycloalkyl groups, C5-C24cycloalkenyl groups, and C12-C24cycloalky nyl groups.

[0895] In a preferred embodiment, each R4is independently selected from the group consisting of hydrogenC,1-C12alkyl groups, C2-C12alkenyl groups, C2-C12alkynyl groups, C6-C12aryl, C2-C12heteroaryl, C3-C12cycloalkyl groups, C5-C12cycloalkenyl groups, and C12cycloalkynyl groups.

[0896] In a preferred embodiment, each R4is independently selected from the group consisting of hydrogenC,1-C4alkyl groups, C2-C4alkenyl groups, C2-C4alkynyl groups, C6aryl, C2-C6heteroaryl, C3-C8cycloalkyl groups, C5-C8cycloalkenyl groups, and C8cycloalkynyl groups.

[0897] Preferably, the R4groups not being hydrogen, optionally contain one or more heteroatoms selected from the group consisting of O, S, NR5, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized.

[0898] Preferably, the R4groups not being hydrogen, are optionally further substituted with one or more substituents selected from the group consisting of - Cl, -F, -Br, -I, -OH, -NH2, -SO3H, -PO3H, -PO4H2, -NO2, -CF3, =O, =NR5, -SR6, C1- C24alkyl groups, C2-C24alkenyl groups, C2-C24alkynyl groups, C6-O24aryl groups, C2-C24heteroaryl groups, C3-C24cycloalkyl groups, C5-C24cycloalkenyl groups, C12-C24cycloalkynyl groups, C3-C24alkyl(hetero)aryl groups, C3-C24(hetero)arylalkyl groups, C4-C24(hetero)arylalkenyl groups, C4-C24

[0899] (hetero)arylalkynyl groups, C4-C24alkenyl(hetero)aryl groups, C4-C24

[0900] alky nyl(hetero) aryl groups, C4-C24alkylcycloalkyl groups, C6-O24

[0901] alkylcycloalkenyl groups, C13-C24alkylcycloalkynyl groups, C4-C24cycloalkylalkyl groups, C6-C24cycloalkenylalkyl groups, C13-C24cycloalkynylalkyl groups, C5-C24alkenylcycloalkyl groups, C7-C24alkenylcycloalkenyl groups, C14-C24

[0902] alkenylcycloalkynyl groups, C5-C24cycloalkylalkenyl groups, C7-C24

[0903] cycloalkenylalkenyl groups, C14-C24cycloalkynylalkenyl groups, C5-C24

[0904] alkynylcycloalkyl groups, C7-C24alkynylcycloalkenyl groups, C14-C24

[0905] alkynylcycloalkynyl groups, C5-C24cycloalkylalkynyl groups, C7-C24

[0906] cycloalkenylalkynyl groups, C14-C24cycloalkynylalkynyl groups, C5-C24

[0907] cycloalkyl(hetero)aryl groups, C7-C24cycloalkenyl(hetero)aryl groups, C14-C24cycloalkynyl(hetero)aryl groups, C5-C24(hetero)arylcycloalkyl groups, C7-C24(hetero)arylcycloalkenyl groups, and C14-C24(hetero)arylcycloalkynyl groups; wherein the substituents optionally contain one or more heteroatoms selected from the group consisting of O, S, NR5, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized.

[0908] Preferably, the R4groups not being hydrogen, are optionally further substituted with one or more substituents selected from the group consisting of - Cl, -F, -Br, -I, -OH, -NH2, -SO3H, -PO3H, -PO4H2, -NO2, -CF3, =O, =NR5, -SR5, C1- C4alkyl groups, C2-C4alkenyl groups, C2-C4alkynyl groups, C6aryl groups, C2-C4heteroaryl groups, C3-C4cycloalkyl groups, C5-C4cycloalkenyl groups, C12cycloalkynyl groups, C3-C12alkyl(hetero)aryl groups, C3-C12(hetero)arylalkyl groups, C4-C12(hetero)arylalkenyl groups, C4-C12(hetero)arylalkynyl groups, C4- C12alkenyl(hetero)aryl groups, C4-C12alkynyl(hetero)aryl groups, C4-C12alkylcycloalkyl groups, C6-C12alkylcycloalkenyl groups, C13-C12alkylcycloalkynyl groups, C4-C12cycloalkylalkyl groups, C6-C12cycloalkenylalkyl groups, C13cycloalkynylalkyl groups, C5-C12alkenylcycloalkyl groups, C7-C12 alkenylcycloalkenyl groups, C14alkenylcycloalkynyl groups, C5-C12

[0909] cycloalkylalkenyl groups, C7-C12cycloalkenylalkenyl groups, C14

[0910] cycloalkynylalkenyl groups, C5-C12alkynylcycloalkyl groups, C7-C12

[0911] alkynylcycloalkenyl groups, C14-C12alkynylcycloalkynyl groups, C5-C12

[0912] cycloalkylalkynyl groups, C7-C12cycloalkenylalkynyl groups, C14

[0913] cycloalkynylalkynyl groups, C5-C12cycloalkyl(hetero)aryl groups, C7-C12cycloalkenyl(hetero)aryl groups, C14cycloalkynyl(hetero)aryl groups, C5-C12(hetero)arylcycloalkyl groups, C7-C12(hetero)arylcycloalkenyl groups, and C14(hetero)arylcycloalkynyl groups;

[0914] wherein the substituents optionally contain one or more heteroatoms selected from the group consisting of O, S, NR5, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized.

[0915] In a preferred embodiment, the R4substituents do not contain

[0916] heteroatoms. In a preferred embodiment, the R4groups are not substituted.

[0917] In another preferred embodiment, the R4groups do not contain heteroatoms.

[0918] R5

[0919] Preferably, each R5is independently selected from the group consisting of hydrogen, C1-C8alkyl groups, C2-C8alkenyl groups, C2-C8alkynyl groups, C6-C12aryl, C2-C12heteroaryl, C3-C8cycloalkyl groups, C5-C8cycloalkenyl groups, C3-C12alkyl(hetero)aryl groups, C3-C12(hetero)arylalkyl groups, C4-C12alkylcycloalkyl groups, C4-C12cycloalkylalkyl groups, C5-C12cycloalkyl(hetero)aryl groups and C5-C12(hetero)arylcycloalkyl groups, wherein the R5groups not being hydrogen are optionally substituted with a moiety selected from the group consisting of -Cl, -F, -Br, -I, -OH, -NH2, -SO3H, -PO3H, -PO4H2,-NO2, -CF3, =O, =NH, and -SH, and optionally contain one or more heteroatoms selected from the group consisting of O, S, NH, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized.

[0920] In a preferred embodiment, the R5groups are not substituted.

[0921] In another preferred embodiment, the R5groups do not contain heteroatoms. Moieties Q, Q1, Q2, Q3, Q4

[0922] In preferred embodiments, g is an integer in a range of from 0 to 12, preferably from 0 to 10, more preferably from 0 to 8, even more preferably from 1 to 6, most preferably from 2 to 4. In other preferred embodiments g is 0. In case more than one moiety selected from the group consisting of Q, Q1, Q2, Q3, and Q4within one compound satisfies Formula (5), each g is independently selected.

[0923] In preferred embodiments, h is 0 or 1. In case more than one moiety selected from the group consisting of Q, Q1, Q2, Q3, and Q4within one compound satisfies Formula (5), each h is independently selected.

[0924] In preferred embodiments, each f belonging to a moiety Q, Q1, Q2, Q3, or Q4is an integer independently selected from a range of from 0 to 24, preferably from 1 to 12, more preferably from 1 to 6, even more preferably from 1 to 3, most preferably f is 0 or 1. In preferred embodiments f is preferably an integer from 12 to 24. In other preferred embodiments, f is 1.

[0925] In preferred embodiments, the group -((R10)h-R11)n-(R10)h-R12satisfies molecules from Group RMshown above.

[0926] In preferred embodiments, the group -((R10)h-R11)n-(R10)h-R12satisfies molecules from Group RM, wherein it is understood that when n is more than 1, e.g. -((R10)h-R11)n-i-(R10)h-Ri2 may be preceded by a group -(R10)h-R11- so as to form a group -(R10)h-R11-((R10)h-R11)n-i-(R10)h-Ri2. It is understood that this follows from the definition of how to write out the repeating units, i.e. -((R10)h-Ru)2- would first be written as -(R10)h-R11-(R10)h-R11- before R10, h, and R11are independently selected.

[0927] Formulae (14), (14a), (14b), (14c), (14d), (14e), and (14f)

[0928] In a preferred embodiment, the Cleaving Agent is a tetrazine satisfying Formula (14):

[0929] Formula (14)

[0930] and preferably including pharmaceutically acceptable salts thereof,

[0931] wherein, Yais selected from the group consisting of Y1, Y2, Y3, Y4, Y5and Ub:

[0932]

[0933] wherein, Ybis selected from the group consisting of Y1, Y2, Y3, Y4, Y5, Ub, hydrogen, X47, and -(SP)D-R87; wherein SP is a spacer, preferably as defined herein, wherein D is 0 or 1, preferably D is 0; wherein when Yais Ub, then Ybis hydrogen, wherein each Q1and Q5, are individually selected from the group consisting of X45,hydrogen, X47and -(SP)D-R87; wherein each Q2and Q4, are individually selected from the group consisting of X46, hydrogen, X47, and— (SP)D— R87; wherein each Q3is individually selected from the group consisting of hydrogen, X47, and— (SP)D— R87; wherein preferably the compound of Formula (14) comprises at least one X45or X46group, wherein each X45individually is selected from the group consisting of N(X50)2, C(X51)2N(X50)2, NX50C(O)X5i, NX50C(S)X5i, OH, SH, C(0)OH, C(S)OH, C(0)SH, C(S)SH, NX50C(O)OX5I,NX50C(S)OX5I,NX50C(0)SX5I, NX50C(S)SX6i, NX50C(O)N(X5I)2, NX5OC(S)N(X5I)2, NX50SO2X5I, NX50SO3X5I, NX50OX5I, SO3H, , S02N(X5I)2, and PO3H2; wherein each X46individually is selected from the group consisting of N(Xso)2, 0(C5ΐ)2N(Cdo)2, NX50C(O)X5I, NX50C(S)X5I„ OH, SH, C(0)OH, C(S)OH, C(0)SH, C(S)SH,

[0934] NX50C(O)OX5I,NX6OC(S)OX6I,NX50C(O)SX5I,NX50C(S)SX5I,NX5OC(0)N(X5I)2, NX5OC(S)N(X5I)2, NX50SO2X5I, NX50SO3X5I, NX50OX5I, SO3H, and PO3H2; wherein each X50and X51individually is selected from the group consisting of hydrogen, X48, and— (SP)D—R87; wherein each X48is preferably independently selected from the group consisting of hydrogen, C1-C4alkyl groups, C2-C4alkenyl groups, and C4-6(hetero)aryl groups; wherein for X48the alkyl groups, alkenyl groups, and (hetero)aryl groups are optionally substituted with a moiety selected from the group consisting of -Cl, -F, -Br, -I, -OH, -NH2, =O, -SH, -SO3H, -PO3H, -PO4H2, and -NO2; and optionally contain at most two heteroatoms selected from the group consisting of -O-, -S-, -NH-, -P-, and -Si-, wherein the N, S, and P atoms are optionally oxidized, wherein each X47is selected from the group consisting of -F, - Cl, -Br, -I, -OX49, -N(X49)2, -SO3, -PO3-, -NO2, -CF3, -SX49, S(=O)2N(X49)2,

[0935] OC(=O)X49, SC(=O) X49, OC(=S)X49, SC(=S)X49,NX49C(=O)-X49, NX49C(=S)-X49, NX49C(=O)O-X49, NX49C(=S)O-X49, NX49C(=O)S-X49, NX49C(=S)S-X49,

[0936] OC(=O)N(X49)2, SC(=O)N(X49)2, OC(=S)N(X49)2, SC(=S)N(X49)2, NX49C(=O)N(X49)2, NX49C(=S)N(X49)2,C(=O)X49,C(=S)X49,C(=O)N(X49)2, C(=S)N(X49)2, C(=O)O-X49, C(=O)S-X49, C(=S)O-X49, C(=S)S-X49, -S(O)X49, -S (O)2X49, NX49S(O)2X49, -ON(X49)2,-NX49OX49, C1-C8alkyl groups, C2-C8alkenyl groups, C2-C8alkynyl groups, C6- C12aryl, C2-C12heteroaryl, C3-C8cycloalkyl groups, C5-C8cycloalkenyl groups, C3-C12alkyl(hetero)aryl groups, C3-C12(hetero)arylalkyl groups, C4-C12

[0937] alkylcycloalkyl groups, C4-C12cycloalkylalkyl groups, C5-C12

[0938] cycloalkyl(hetero)aryl groups and C5-C12(hetero)arylcycloalkyl groups,

[0939] wherein the alkyl groups, alkenyl groups, alkynyl groups, aryl, heteroaryl, cycloalkyl groups, cycloalkenyl groups, alkyl(hetero)aryl groups, (hetero)arylalkyl groups, alkylcycloalkyl groups, cycloalkylalkyl groups, cycloalkyl(hetero)aryl groups and (hetero)arylcycloalkyl groups are optionally substituted with a moiety selected from the group consisting of -Cl, -F, -Br, -I, -OX49, -N(X49)2, -SO3X49, - PO3(X49)2,-PO4(X49)2,-NO2, -CF3, =O, =NX49, and -SX49, and optionally contain one or more heteroatoms selected from the group consisting of O, S, NX49, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized; wherein X49is selected from the group consisting of hydrogen, C1-C8alkyl groups, C2-C8alkenyl groups, C2-C8alkynyl groups, C6-C12aryl, C2-C12heteroaryl, C3-C8cycloalkyl groups, C5-C8cycloalkenyl groups, C3-C12alkyl(hetero)aryl groups, C3-C12(hetero)arylalkyl groups, C4-C12alkylcycloalkyl groups, C4-C12cycloalkylalkyl groups, C5-C12cycloalkyl(hetero)aryl groups and C5-C12(hetero)arylcycloalkyl groups, wherein the X49groups not being hydrogen are optionally substituted with a moiety selected from the group consisting of -Cl, -F, -Br, -I, -OH, -NH2, -SO3H, -PO3H, -PO4H2,-NO2, -CF3, =O, =NH, and -SH, and optionally contain one or more heteroatoms selected from the group consisting of O, S, NH, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized; wherein for each individual Yaand Ybpreferably at most two, more preferably at most one of Q1, Q2, Q3, Q4,and Q5are said R87; wherein the compound according to Formula (14) preferably comprises at most four R87moieties, more preferably at most two R87moieties, most preferably at most one R87; wherein the compound according to Formula (14) preferably comprises at least one R87; wherein preferably for each individual Yaand Ybat most three, more preferably at most two of Q1, Q2, Q3, Q4,and Q5are not hydrogen; wherein preferably for each individual Yaand Ybat most two of Q1, Q2, Q3, Q4,and Q5are X45or X46, wherein preferably for each individual Yaand Ybone of Q1, Q2, Q4,and Qs is X45 or X46, wherein preferably both Yaand Ybcomprise at least one X45 or X46, wherein preferably both Yaand Ybcomprise one X45or X46, wherein preferably both Yaand Ybcomprise one X45or X46, wherein preferably the X45comprised in Yais the same as the X45comprised in Yb, and / or the X46comprised in Yais the same as the X46comprised in Yb, wherein

[0940] preferably Yaand Ybare both independently selected Yi, or both independently selected Y2, or both independently selected Y3, or both independently selected Y4, or both independently selected Y5.

[0941] In a preferred embodiment, in Formula (14) or in any one of Formulae (14a)-(14f), when Q1is a X47 or -(SP)D-R87, then for Q1the X47and the R87are not a group in accordance with the definition of X45.

[0942] In a preferred embodiment, in Formula (14) or in any one of Formulae (14a)-(14f), when Q5 is a X47 or -(SP)D-R87, then for Q5 the X47and the R87are not a group in accordance with the definition of X45.

[0943] In a preferred embodiment, in Formula (14) or in any one of Formulae (14a)-(14f), when Q2is a X47 or -(SP)D-R87, then for Q2the X47and the R87are not a group in accordance with the definition of X46.

[0944] In a preferred embodiment, in Formula (14) or in any one of Formulae (14a)-(14f), when Q4is a X47 or -(SP)D-R87, then for Q4the X47and the R87are not a group in accordance with the definition of X46. In preferred embodiments Yaequals Yb. In preferred embodiments Yais selected from Yi, Y2, Y3, Y4 or Y5 and Ybis hydrogen, X47or -(SP)D-R87. In preferred embodiments Yais selected from Yi, Y2, Y3, Y4or Y5and Ybis hydrogen. In preferred embodiments the compound according to Formula (14) does not comprise a R87. In preferred embodiments, X50is hydrogen. In preferred

[0945] embodiments when X45or X46is N(Xso)2, then one X50is hydrogen and one X50is X48or— (SP)D— R87. In preferred embodiments Formula (14) does not comprise X46.

[0946] In preferred embodiments, the Cleaving Agent is a tetrazine satisfying any one of Formulae (14a)-(14f):

[0947] wherein Q6is as defined for Q1in Formula (14), Q71S as defined for Q2in

[0948] Formula (14), Q8is as defined for Q3in Formula (14), Q9is as defined for Q4in Formula (14), and Q1o is as defined for Q5 in Formula (14), wherein preferably at most two, more preferably at most one of Q1, Q2, Q3, Q4, and Q5are said -(SP)D-R87; wherein preferably at most two, more preferably at most one of(¾6, Q7, Q8, Q9, and Q10are said -(SP)D-R87; wherein preferably the compound according to any one of Formulae (14a) to (14f) comprises at most four R87moieties, more preferably at most two R87moieties; wherein the compound according to Formulae (14a)-(14f) preferably comprises at least one R87; wherein preferably at most six, more preferably at most four of Q1, Q2, Q3, Q4, Q5,Q6, Q7,

[0949] Q8, Q9, Q10are not hydrogen, wherein preferably the X45or X46groups are identical.

[0950] In a preferred embodiment, in Formulae (14b), (14b), and (14f) when Q6is a X47or— (SP)D— R87, then for (¾6 the X47and the R87are not a group in accordance with the definition of X45.

[0951] In a preferred embodiment, in Formulae (14c)-(14f) when Q10is a X47or— (SP)D— R87, then for Q10the X47and the R87are not a group in accordance with the definition of X45.

[0952] In a preferred embodiment, in Formulae (14a), (14c), and (14e) when Q7is a X47or— (SP)D—R87, then for Q7the X47and the R87are not a group in accordance with the definition of X46.

[0953] In a preferred embodiment, in Formulae (14a), (14b), (14e), and (14f) when Q9is a X47or -(SP)D-R87, then for Q9the X47and the R87are not a group in accordance with the definition of X46. X45

[0954] In a preferred embodiment, each X45individually is selected from the group consisting of N(X50)2, NX50C(O)X5I, NX50C(S)X5I,OH, SH, NX50C(O)OX5I,

[0955] NX50C(S)OX5I,NX50C(0)SX5I,NX5OC(S)SX5 I,NX5OC(0)N(X5I)2, NX5OC(S)N(X5I)2, NX50SO2X5I, NX50SO3X5I, NX50OX5I, and S02N(X5I)2.

[0956] In a preferred embodiment, each X45individually is selected from the group consisting of N(X50)2, NX50C(O)X51, NX50C(S)X51, OH and SH.

[0957] In a preferred embodiment, each X45individually is selected from the group consisting of NX50C(0)OX5I,NX50C(S)OX5I,NX5oC(0)SX5i,NX5OC(S)SX5I,NX5OC(0)N(X5I)2, NX5OC(S)N(X5I)2, NX50SO2X5I, NX50SO3X5I, NX50OX5I, In a preferred embodiment, X45is selected from the group consisting of NHX50, C(X51)2NH2, CHX5INH2, CH2N(X5O)2, CH2NHX5O, NHC(O)X51, NHC(S)X51, OH, and SH. In a preferred embodiment, X45is NHX50. In a preferred embodiment,

[0958] X45is C(X51)2NH2. In a preferred embodiment, X45is CHX51NH2. In a preferred embodiment, X45is CH2N(X50)2. In a preferred embodiment, X45is CH2NHX51.

[0959] In a preferred embodiment, X45is NH2. In a preferred embodiment, X45is

[0960] CH2NH2. In a preferred embodiment, X45is NHC(O)X51. In a preferred

[0961] embodiment, X45is NHC(S)X51. In a preferred embodiment, X45is OH.

[0962] In a preferred embodiment, X45is SH. In a preferred embodiment, X45is SO2NH2.

[0963] X46

[0964] In a preferred embodiment, X46is individually selected from the group consisting of N(X5O)2, NX5OC(O)X51,NX5OC(O)OX51, andNX5oC(O)N(X51)2,. In a preferred embodiment, X46is selected from the group consisting of N(X50)2, and

[0965] NCdoO(O)C5ΐ,. In a preferred embodiment, X46is selected from the group consisting of NHX50and NHC(O)X51. In a preferred embodiment, X46is NHX50.

[0966] In a preferred embodiment, X46is NH2. In a preferred embodiment, X46is

[0967] NHC(O)X51. X47

[0968] In a preferred embodiment, each X47is individually selected from the group consisting of F, -OH, -NH2, -SO3·,-NO2, -CF3, -SH, C1-C6alkyl groups, C6aryl groups, C4-C5heteroaryl groups, C5-C8alkyl(hetero)aryl groups, C5-C8

[0969] (hetero)arylalkyl groups, C4-C8alkylcycloalkyl groups, and C4-C8cycloalkylalkyl groups. In a more preferred embodiment, each X47is individually selected from the group consisting of F, -SO3·,-NO2, -CF3, C1-C6alkyl groups, Ce aryl groups, C4-C5heteroaryl groups, C5-C8alkyl(hetero)aryl groups, C5-C5(hetero)arylalkyl groups, C4-C8alkylcycloalkyl groups, and C4-C8cycloalkylalkyl groups.

[0970] In a preferred embodiment, the X47substituents do not contain heteroatoms.

[0971] In a preferred embodiment, the X47groups are not substituted.

[0972] In another preferred embodiment, the X47groups do not contain heteroatoms. X48

[0973] In a preferred embodiment, each X48is independently selected from the group consisting of hydrogen, C1-C4alkyl groups, C2-C4alkenyl groups, and C4-6

[0974] (hetero)aryl groups. For X48the alkyl groups, alkenyl groups, and (hetero)aryl groups are optionally substituted with a moiety selected from the group

[0975] consisting of -Cl, -F, -Br, -I, -OH, -NH2, =O, -SH, -SO3H, -PO3H, -PO4H2and -NO2; and optionally contain at most two heteroatoms selected from the group

[0976] consisting of -O-, -S-, -NH-, -P-, and -Si-, wherein the N, S, and P atoms are optionally oxidized. In a preferred embodiment, X48 is C1-C4alkyl.

[0977] In a preferred embodiment, the X48substituents do not contain heteroatoms.

[0978] In a preferred embodiment, the X48groups are not substituted.

[0979] In another preferred embodiment, the X48 groups do not contain heteroatoms.

[0980] X49

[0981] In preferred embodiments, X49is selected from the group consisting of hydrogen, C1-C8alkyl groups, C2-C8alkenyl groups, C2-C8alkynyl groups, C6-C12aryl, C2- C12heteroaryl, C3-C8cycloalkyl groups, C5-C8cycloalkenyl groups, C3-C12alkyl(hetero)aryl groups, C3-C12(hetero)arylalkyl groups, C4-C12alkylcycloalkyl groups, C4-C12cycloalkylalkyl groups, C5-C12cycloalkyl(hetero)aryl groups and C5-C12(hetero)arylcycloalkyl groups, wherein the X49 groups not being hydrogen are optionally substituted with a moiety selected from the group consisting of -Cl, -F, -Br, -I, -OH, -NH2, -SO3H, -PO3H, -PO4H2,-NO2, -CF3, =O, =NH, and -SH, and optionally contain one or more heteroatoms selected from the group consisting of O, S, NH, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized.

[0982] In preferred embodiments, X49is selected from the group consisting of hydrogen, C1-C4alkyl groups, C2-C4alkenyl groups, C2-C4alkynyl groups, C6-C8aryl, C2-C8heteroaryl, C3-C6cycloalkyl groups, C5-C6cycloalkenyl groups, C3-C10alkyl(hetero)aryl groups, C3-C10(hetero)arylalkyl groups, C4-C8alkylcycloalkyl groups, C4-C8cycloalkylalkyl groups, C5-C10cycloalkyl(hetero)aryl groups and C5- C10(hetero)arylcycloalkyl groups, wherein the X49groups not being hydrogen are optionally substituted with a moiety selected from the group consisting of -Cl, -F, -Br, -I, -OH, -NH2, -SO3H, -PO3H, -PO4H2,-NO2, -CF3, =O, =NH, and -SH, and optionally contain one or more heteroatoms selected from the group consisting of O, S, NH, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized. In a preferred embodiment, the X49substituents do not contain heteroatoms. In a preferred embodiment, the X49groups are not substituted. In another preferred embodiment, the X49groups do not contain heteroatoms.

[0983] X50

[0984] In a preferred embodiment, each X50is individually selected from the group consisting of hydrogen, X48, and— (SP)D— R87. In a preferred embodiment, X50is X48. In a preferred embodiment, X50is— (SP)D— R87. In a preferred embodiment, X50is H. X51

[0985] In a preferred embodiment, each X51is individually selected from the group consisting of hydrogen, X48, and— (SP)D— R87. In a preferred embodiment, X51is X48. In a preferred embodiment, X51is— (SP)D— R87. In a preferred embodiment, X5Iis H. Q1

[0986] In a preferred embodiment, in any one of Formulae (14)-(14f) Q1is selected from the group consisting of hydrogen, X47, and— (SP)D— R87. In a preferred embodiment, Q1in any one of Formulae (14)-(14f) is hydrogen. In a preferred embodiment, Q1in any one of Formulae (14)-(14f) is X47. In a preferred embodiment, Q1in any one of Formulae (14)-(14f) is a R87, and preferably Q2, Q3, Q4, Q5, Q6, Q7, Q8, Q9, and Q10are X45, X46, or hydrogen. Q2

[0987] In a preferred embodiment, Q2in any one of Formulae (14)-(14f) is selected from the group consisting of hydrogen X47, and— (SP)D—R87. In a preferred embodiment, Q2in any one of Formulae (14)-(14f) is hydrogen. In a preferred embodiment, Q2is in any one of Formulae (14)-(14f) X47. In a preferred embodiment, Q2in any one of Formulae (14)-(14f) is -(SP)D-R87, and preferably Q1, Q3, Q4, Q5, Q6, Q7, Q8, Q9, and Q10are X45, X46, or hydrogen. Q,3

[0988] In a preferred embodiment, Q3in any one of Formulae (14)-(14f) is selected from the group consisting of hydrogen X47, and— (SP)D— R87. In a preferred embodiment, Q3in any one of Formulae (14)-(14f) is hydrogen. In a preferred embodiment, Q3in any one of Formulae (14)-(14f) is X47. In a preferred embodiment, Q3in any one of Formulae (14)-(14f) is -(SP)D-R87, and preferably Q1, Q2, Q4, Q5, Q6, Q7, Q8, Q9, and Q10are X45, X46, or hydrogen. Q4

[0989] In a preferred embodiment, Q4in any one of Formulae (14)-(14f) is selected from the group consisting of hydrogen X47, and— (SP)D—R87. In a preferred embodiment, Q4in any one of Formulae (14)-(14f) is hydrogen. In a preferred embodiment, Q4in any one of Formulae (14)-(14f) is X47. In a preferred embodiment, Q4in any one of Formulae (14)-(14f) is -(SP)D-R87, and preferably Q1, Q2, Q3, Q5, Q6, Q7, Q8, Q9and Q10are X45, X46, or hydrogen.

[0990] Q5

[0991] In a preferred embodiment, Q5in any one of Formulae (14)-(14f) is selected from the group consisting of hydrogen X47, and— (SP)D— R87. In a preferred embodiment, Q5in any one of Formulae (14)-(14f) is hydrogen. In a preferred embodiment, Q5in any one of Formulae (14)-(14f) is X47. In a preferred embodiment, Q5is— (SP)D— R87, and preferably Q1, Q2, Q3, Q4, Q6, Q7, Q8, Q9and Q10are X45, X46, or

[0992] hydrogen. Q6

[0993] In a preferred embodiment, Q6in any one of Formulae (14)-(14f) is selected from the group consisting of hydrogen X47, and— (SP)D—R87. In a preferred embodiment, Q6in any one of Formulae (14)-(14f) is hydrogen. In a preferred embodiment, Q6in any one of Formulae (14)-(14f) is X47. In a preferred embodiment, Q6in any one of Formulae (14)-(14f) is -(SP)D-R87, and preferably Q1, Q2, Q3, Q4, Q5, Q7, Q8, Q9and Q10are X45, X46, or hydrogen. QT

[0994] In a preferred embodiment, Q7in any one of Formulae (14)-(14f) is selected from the group consisting of hydrogen X47, and— (SP)D—R87. In a preferred embodiment, Q7in any one of Formulae (14)-(14f) is hydrogen. In a preferred embodiment, Q7in any one of Formulae (14)-(14f) is X47. In a preferred embodiment, Q7in any one of Formulae (14)-(14f) is -(SP)D-R87, and preferably Q1, Q2, Q3, Q4, Q5, Q6, Q8, Q9and Q10are X45, X46, or hydrogen. Q8

[0995] In a preferred embodiment, Q8in any one of Formulae (14)-(14f) is selected from the group consisting of hydrogen X47, and— (SP)D—R87. In a preferred embodiment, Qs in any one of Formulae (14)-(14f) is hydrogen. In a preferred embodiment, Qs in any one of Formulae (14)-(14f) is X47. In a preferred embodiment, Q8in any one of Formulae (14)-(14f) is -(SP)D-R87, and preferably Q, Q2, Q3, Q4, Q5, Q6, Q7, Q9and Q10are X45,X46, or hydrogen.

[0996] Q,9

[0997] In a preferred embodiment, Q9in any one of Formulae (14)-(14f) is selected from the group consisting of hydrogen X47, and— (SP)D—R87. In a preferred embodiment, Q9in any one of Formulae (14)-(14f) is hydrogen. In a preferred embodiment, Q9in any one of Formulae (14)-(14f) is X47. In a preferred embodiment, Q9in any one of Formulae (14)-(14f) is -(SP)D-R87, and preferably Q1, Q2, Q3, Q4, Q5, Q6, Q7,Q8and Q10are X45, X46, or hydrogen.

[0998] Q10

[0999] In a preferred embodiment, Q10in any one of Formulae (14)-(14f) is selected from the group consisting of hydrogen X47, and— (SP)D—R87. In a preferred embodiment, Q10in any one of Formulae (14)-(14f) is hydrogen. In a preferred embodiment, Q10in any one of Formulae (14)-(14f) is X47. In a preferred embodiment, Q10in any one of Formulae (14)-(14f) is -(SP)D-R87, and preferably Q, Q2, Q3, Q4, Q5, Q6, Q7, Q8and Q9are X45, X46, or hydrogen. Formula (14a)

[1000] In a preferred embodiment, the compound according to the invention is a compound according to Formula (14a), wherein preferably, each individual X45and Q2-Q4, Q7-Q9are as described herein.

[1001] In a preferred embodiment, the compound according to the invention is a compound according to Formula (14a), wherein both X45are the same and are selected from the group consisting of NH2, NHC(O)X51, NX50C(O)OX5i,

[1002] NX5OC(O)N(X51)2, NX5OC(S)N(X51)2, OH, and SH; and Q2-Q4, Q7-Q9are hydrogen.

[1003] In a preferred embodiment, the compound according to the invention is a compound according to Formula (14a), wherein both X45are the same and are selected from the group consisting of NH2, NHC(O)X51, and OH; and Q2-Q4, Q7-Q9are hydrogen.

[1004] Formula (14b)

[1005] In a preferred embodiment, the compound according to the invention is a compound according to Formula (14b), wherein preferably, each individual X46and Q1, Q3-Q4, Q6, Q8-Q9are as described herein.

[1006] In a preferred embodiment, the compound according to the invention is a compound according to Formula (14b), wherein both X46are the same and are NH2or NHC(O)X5i, and Q1, Q3-Q4, Q6, Q8-Q9are hydrogen.

[1007] Formula (14c)

[1008] In a preferred embodiment, the compound according to the invention is a compound according to Formula (14c), wherein preferably, each individual X45and Q2-Q3, Q5, Q7,Q8, Q10are as described herein.

[1009] In a preferred embodiment, the compound according to the invention is a compound according to Formula (14c), wherein both X45are the same and are selected from the group consisting of NH2, NHC(O)X51, NX50C(O)OX51,

[1010] NX50C(O)N(X51)2, NX50C(S)N(X51)2, OH, and SH; and Q2-Q3, Q5, Q7,Q8, Q10are hydrogen. In a preferred embodiment, the compound according to the invention is a compound according to Formula (14c), wherein both X45are the same and are NH2, NHC(O)X51, and OH, and Q2-Q3, Q5, Q7,Q8, Q10are hydrogen.

[1011] Formula (14d)

[1012] In a preferred embodiment, the compound according to the invention is a compound according to Formula (14d), wherein preferably each individual X46and Q1, Q3, Q5, Qe, Q8, Q10are as described herein.

[1013] In a preferred embodiment, the compound according to the invention is a compound according to Formula (14d), wherein both X46are the same and are NH2or NHC(O)X5i, and Q1, Q3, Q5, Qe, Q8, Q10are hydrogen.

[1014] Formula (14e)

[1015] In a preferred embodiment, the compound according to the invention is a compound according to Formula (14e), wherein preferably each individual X45and Q2, Q4, Q5, Q7, Q9, Q10are as described herein.

[1016] In a preferred embodiment, the compound according to the invention is a compound according to Formula (14e), wherein both X45are the same and are selected from the group consisting of NH2, NHC(O)Xsi, NXsoC(O)OX5i,

[1017] NX50C(O)N(X51)2, NX50C(S)N(X51)2, OH, and SH; and Q2, Q4, Q5, Q7, Q9, Q10are hydrogen.

[1018] In a preferred embodiment, the compound according to the invention is a compound according to Formula (14e), wherein both X45are the same and are NH2, NHC(O)X51, and OH, and Q2, Q4, Q5, Q7, Q9, Q10are hydrogen.

[1019] Formula (14f)

[1020] In a preferred embodiment, the compound according to the invention is a compound according to Formula (14f), wherein preferably each individual X46and Q1, Q4, Q5, Q6, Q9, Q10are as described herein.

[1021] In a preferred embodiment, the compound according to the invention is a compound according to Formula (14f), wherein both X46are the same and are NH2or NHC(O)X5i, and Q1, Q4, Q5, Q6, Q9, Q10are hydrogen. In a preferred embodiment, the Cleaving Agent is according to Formula (14) and comprises at least one, preferably two, X45groups.

[1022] In a preferred embodiment, the Cleaving Agent is according to Formula (14a), (14c), or (14e).

[1023] R87

[1024] Preferably, a R87in relation to the invention is a moiety that modulates the pharmacokinetics of a compound. Thus, in a preferred embodiment R87is a pharmacokinetics-modulating moiety (PKmoiety). The functions of the R87include, but are not limited to, one or more of delaying clearance of said compound, affecting the volume of distribution of said compound ( e.g . reducing or increasing the volume of distribution), affecting the biodistribution of said compound, achieving spatial control over its reaction with the Trigger, affecting (more particularly avoiding) the metabolism of said compound, and / or affecting (more particularly avoiding) the (undesired) sticking or (undesired) uptake of said compound to tissues. The skilled person is well aware of such groups, and how to synthesize these.

[1025] In preferred embodiments, each R87is independently selected from the group consisting of organic molecules, inorganic molecules, organometallic molecules, resins, beads, glass, microparticles, nanoparticles, gels, surfaces, and cells. Preferably, R87is independently selected from the group consisting of organic molecules, and inorganic molecules.

[1026] In a preferred embodiment the R87serves to increase the blood circulation time, increasing reaction time with the Trigger.

[1027] In a preferred embodiment the R87serves modulate the pharmacokinetics of a reaction product between a dienophile of this invention and a diene as defined herein.

[1028] Without wishing to be bound by theory, it is believed that the function and performance of the tetrazine as defined herein in a bioorthogonal reaction is not significantly affected by the nature of the R87.

[1029] In a preferred embodiment, each R87is individually selected from the group consisting of biomolecule, polymer, peptide, peptoid, dendrimer, protein, carbohydrate, oligonucleotide, oligosaccharide, aptamer, steroid, lipid, albumin, albumin-binding moiety, dye moiety, fluorescent moiety, imaging probe, and a Targeting Agent (TT); and wherein the R87is optionally bound to the tetrazine via a Spacer (SP). Typically, a suitable polymer as a R87is polyethyleneglycol (PEG). Such suitable PEG includes PEG with a number of repeating units in a range of from 2 to 4000, and PEG with a molecular weight in a range of from 200 Da to 100,000 Da.

[1030] In a preferred embodiment, the R87is a moiety according to Formula (5).

[1031] In a preferred embodiment, the R87is a moiety according to Formula (5), and is directly linked to the remainder of a compound according to any one of Formulae (14)-(14f), for example without a spacer SPbetween the R87and the remainder of the moiety Yaor Ybof Formula (14) or the pyridyl moiety of the compound according to any one of Formulae (14a)-(14f).

[1032] In a preferred embodiment, the R87is a moiety according to Formula (5), and is directly linked to the remainder of a, for example without a spacer SPbetween the R87and the remainder of the moiety Yaor Ybof any one of Formulae (4), (11), and (14); or the pyridyl moiety of the compound according to any one of Formulae (14a)-(14f), and if attached to an amine functionality of X45or X46, z in Formula (5) is not 0.

[1033] In a preferred embodiment, the R87is linked to the remainder of a compound via a spacer SPas defined herein.

[1034] In a preferred embodiment, the R87is linked to the remainder of a compound optionally via a spacer SPas defined herein and each R87is

[1035] individually selected from the group consisting of biomolecule, polymer, peptide, peptoid, dendrimer, protein, carbohydrate, oligonucleotide, oligosaccharide, lipid, micelle, liposomes, polymersome, particle, nanoparticle, microparticle, bead, gel, metal complex, organometallic moiety, albumin, albumin-binding moiety, dye moiety, fluorescent moiety, imaging probe, and a Targeting Agent (TT).

[1036] In a preferred embodiment, one or multiple copies of the compound of the invention may be conjugated to a R87that is a membrane translocation moiety (e.g. adamantine, poly-lysine / arginine, TAT, human lactoferrin) to reach an intracellular Prodrug. Exemplary references regarding such moieties include: Trends in Biochemical Sciences, 2015,. 40, 12, 749; J. Am. Chem. Soc. 2015, 137, 12153-12160; Pharmaceutical Research, 2007, 24, 11, 1977.

[1037] With respect to application in a cellular environment, such as in vivo, depending on the position of the Trigger-Construct (e.g. inside the cell or outside the cell) the Cleaving Agent is designed to be able to effectively reach this Trigger-Construct. Therefore, the Cleaving Agent can for example be tailored by varying its log P value, its reactivity or its charge, and this can optionally be achieved by the R87.

[1038] In a preferred embodiment, the tetrazine compounds of the invention comprise an imaging moiety instead of a R87. In other embodiments, the R87is or comprises an imaging moiety. In this preferred embodiment the imaging moiety is bound to the remainder of the compounds of the invention in the same way as the R87. In this embodiment the R87equals an imaging moiety. In a preferred embodiment, the compounds of the invention can comprise one or more imaging moieties and one or more R87moieties.

[1039] In a preferred embodiment, the R87is or comprises an imaging moiety.

[1040] Preferred imaging moieties are radionuclide-chelates complexes, radiolabeled molecules (e.g. with18F,124I), and fluorescent dyes.

[1041] In a preferred embodiment, the R87is an imaging moiety that comprises at least one18F isotope.

[1042] In a preferred embodiment, the R87comprises a chelating moiety, preferably a chelating moiety as described herein.

[1043] In a preferred embodiment, the R87includes but is not limited to amino acids, nucleosides, nucleotides, carbohydrates, and biopolymer fragments, such as oligo- or polypeptides, oligo- or polypeptoids, or oligo- or polylactides, or oligo- or poly-carbohydrates, oligonucleotides, varying from 2 to 200, particularly 2 to 113, preferably 2 to 50, more preferably 2 to 24 and more preferably 2 to 12 repeating units.

[1044] According to one embodiment, the Cleaving Agent can be a multimeric compound, comprising a plurality of tetrazines. According to one preferred embodiment, the Cleaving Agent can be a multimeric compound, comprising a plurality of tetrazines bound to one R87. These multimeric compounds can be but are not limited to biomolecules, peptide, peptoid, protein, oligonucleotide, oligosaccharide, polymersome, bead, gel, polymers, dendrimers, liposomes, micelles, particles, polymer particles, or other polymeric constructs.

[1045] In a preferred embodiment, the R87is a polymer. This includes linear or branched polyalkylene glycols such as polyethylene glycol (PEG) or polypropylene glycol (PPG) chains varying from 2 to 200, particularly 2 to 113, preferably 2 to 50, more preferably 2 to 24 and more preferably 2 to 12 repeating units. It is preferred that when polyalkylene glycols such as PEG and PPG polymers are only bound via one end of the polymer chain, that the other end is terminated with -OCH3, -OCH2CH3, OCH2CH2CO2H.

[1046] Other polymeric R87moieties are polymers and copolymers such as poly-(2- oxazoline, poly(A -(2-hydroxypropyl)methacrylamide) (HPMA), polylactic acid (PLA), polylactic-glycolic acid (PLGA), polyglutamic acid (PG), dextran, polyvinylpyrrolidone (PVP), poly(l-hydroxymethylethylene hydroxymethyl- formal (PHF). Other exemplary polymers are polysaccharides,

[1047] glycopolysaccharides, glycolipids, polyglycoside, polyacetals, polyketals, polyamides, polyethers, polyesters. Examples of naturally occurring

[1048] polysaccharides that can be used are cellulose, amylose, dextran, dextrin, levan, fucoidan, carraginan, inulin, pectin, amylopectin, glycogen, lixenan, agarose, hyaluronan, chondroitinsulfate, dermatansulfate, keratansulfate, alginic acid and heparin. In yet other exemplary embodiments, the polymer is a copolymer of a polyacetal / polyketal and a hydrophilic polymer selected from the group consisting of polyacrylates, polyvinyl polymers, polyesters, polyorthoesters, polyamides, oligopeptides, polypeptides and derivatives thereof. Exemplary preferred polymeric R87moieties are PEG, HPMA, PLA, PLGA, PVP, PHF, dextran, oligopeptides, and polypeptides.

[1049] In some aspects of the invention polymeric R87moieties have a molecular weight ranging from 2 to 200 kDa, from 2 to 100 kDa, from 2 to 80 kDa, from 2 to 60 kDa, from 2 to 40 kDa, from 2 to 20 kDa, from 3 to 15 kDa, from 5 to 10 kDa, from 500 dalton to 5 kDa.

[1050] Other exemplary R87moieties are dendrimers, such as poly(propylene imine) (PPI) dendrimers, PAMAM dendrimers, and glycol based dendrimers. In a preferred embodiment the R87equals Group RM.

[1051] In a preferred embodiment the R87serves to increase the blood circulation time, increasing reaction time with the Trigger.

[1052] In a preferred embodiment the R87serves to modulate the

[1053] pharmacokinetics of a reaction product between a dienophile and diene of this invention.

[1054] In a preferred embodiment, the Cleaving Agent is designed to be cell impermeable as a result of its log P value or its charge, and this can optionally be achieved by the R87.

[1055] In embodiments where it is required that the Cleaving Agent has an extracellular volume of distribution it is preferred that the Log P of the Cleaving Agent is at most 2, preferably at most 1, more preferably at most 0, even more preferably at most -1.

[1056] In embodiments where it is required that the Cleaving Agent has an intracellular volume of distribution it is preferred that the Log P of the Cleaving Agent is at least -1, preferably at least 0, more preferably at least 1, even more preferably at least 2.

[1057] In embodiments where it is required that the Cleaving Agent has an extracellular volume of distribution it is preferred that the Agent has a negative net charge at pH 7.

[1058] In embodiments where it is required that the Cleaving Agent has an intracellular volume of distribution it is preferred that the Agent has a molecular weight of less than 1000 Da, preferably less than 500 Da.

[1059] In embodiments where it is required that the Cleaving Agent has an extracellular volume of distribution it is preferred that the Agent has a molecular weight of more than 500 Da, preferably more than 1 kDa, more preferably more than 2 kDa.

[1060] In embodiments where it is required that the Cleaving Agent has slow or inefficient extravasation from circulation into tissues it is preferred that the Agent has a molecular weight of more than 5 kDa, preferably more than 60 Da, more preferably more than 150 Da, even more preferably more than 500 kDa, In preferred embodiments wherein the Cleaving Agent is not cell permeable, R87can be a protein or polymer,

[1061] In preferred embodiments the R87reduces the extravasation of the Cleaving Agent from blood into target tissue, by virtue of its large size and / or by the presence of a clearance- directing group (i.e. as R98). For example, R87being a PLGA microparticle will allow efficient IEDDA reaction with Administration Agent in circulation but will hamper efficient extravasation of the Cleaving Agent into tumor tissue, and will result in rapid clearance by the liver. Likewise, R87being an albumin protein modified with ca. 10 galactose moieties (i.e.

[1062] clearance-directing groups, as R98) to ensure rapid uptake by the liver, affords efficient IEDDA reaction in blood with no or minimal in mimizing extravasation into tumor tissue. Reference is made to [Rossin et al J. Nucl. Med. 2013, 4, 11, 1989-1995]. Likewise R87can be a small moiety comprising a Clearance-directing group to favor IEDDA reaction in blood vs. in tumor tissue.

[1063] Conversely, if whole body extracellular Label cleavage is desired the R87can be a 20 or 40 kDa PEG or albumin or an albumin-binding moiety ensuring prolonged retention in circulation, optionally combined with EPR based targeting of tumor tissue.

[1064] In one embodiment the Administration Agent specifically binds or complexes with a cell surface molecule, such as a cell surface receptor or antigen, for a given cell population. Following specific binding or complexing with the receptor, the cell is permissive for uptake of the Administration Agent, which then internalizes into the cell. The subsequently administered Cleaving Agent will then enter the cell and cleave the Administration Agent, releasing the Effector Moiety inside the cell. In another embodiment the Administration Agent specifically binds or complexes with a cell surface molecule, such as a cell surface receptor or antigen, for a given cell population. Following specific binding or complexing the receptor, the cell is not permissive for uptake of the

[1065] Administration Agent. The subsequently administered Cleaving Agent will then cleave the Administration Agent on the outside of the cell.

[1066] In an image cycling embodiment, centered on sequential imaging procedures of the same or different Primary Targets, it is preferred that the Cleaving Agent acts systemically (i.e. in the whole body). In other image cycling embodiments it is preferred that the Cleaving Agent comprises a R87that is a TTand selectively cleaves the Label at the Primary Target being imaged.

[1067] Targeting Agent TT

[1068] In preferred embodiments, a Targeting Agent TTis used to bind a Primary Target.

[1069] In preferred embodiments, the dienes of this invention are bound to a Targeting Agent TT. A TTbound to a diene can be advantageously used in relation to the invention, as a TTmay direct the diene to, or retain the diene at a location where the Label needs to be released from the compound of Formula (1). For example, to increase the target / non-target ratio of the Label, it may be preferred to direct the diene to, or retain the diene in the blood if that is not the target. Then, the Cleaving Agent will mainly release the Label in the blood, after which the Label is rapidly cleared. The Label at the target ( e.g . a tumor) is not released, thus increasing the target / non-target ratio of the Label.

[1070] In preferred embodiments the TTis used in affecting (more particularly avoiding) the metabolism of the diene, and / or affecting (more particularly avoiding) the (undesired) sticking or (undesired) uptake of the diene to tissues.

[1071] In preferred embodiments, the TTis an Administration Agent.

[1072] The skilled person is well aware of such groups, and how to synthesize these.

[1073] In a preferred embodiment, the TTis selected from the group consisting of polymer, polymer particle, peptide, peptoid, dendrimer, protein, carbohydrate, oligonucleotide, oligosaccharide, lipid, liposome, albumin, albumin- binding moiety. Typically, a suitable polymer is poly ethyleneglycol (PEG). Such suitable PEG includes PEG with a number of repeating units in a range of from 2 to 4000, and PEG with a molecular weight in a range of from 200 Da to 100,000 Da.

[1074] In a preferred embodiment, the TTbound to the diene includes but is not limited to amino acids, nucleosides, nucleotides, carbohydrates, and

[1075] biopolymer fragments, such as oligo- or polypeptides, oligo- or polypeptoids, or oligo- or polylactides, or oligo- or poly-carbohydrates, oligonucleotides, varying from 2 to 200, particularly 2 to 113, preferably 2 to 50, more preferably 2 to 24 and more preferably 2 to 12 repeating units.

[1076] In a preferred embodiment, the TTbound to the diene is a polymer. This includes linear or branched polyalkylene glycols such as polyethylene glycol (PEG) or polypropylene glycol (PPG) chains varying from 2 to 200, particularly 2 to 113, preferably 2 to 50, more preferably 2 to 24 and more preferably 2 to 12 repeating units. It is preferred that when polyalkylene glycols such as PEG and PPG polymers are only bound via one end of the polymer chain, that the other end is terminated with -OCH3, -OCH2CH3, OCH2CH2CO2H.

[1077] Other suitable polymeric TTMoieties include polymers and copolymers such as poly-(2-oxazoline), poly (N- (2 -hydroxypropyl) methacrylamide) (HPMA), polylactic acid (PLA), polylactic-glycolic acid (PLGA), polyglutamic acid (PG), dextran, polyvinylpyrrolidone (PVP), poly(l-hydroxymethylethylene

[1078] hydroxymethyl-formal (PHF). Other exemplary polymers are polysaccharides, glycopolysaccharides, glycolipids, polyglycoside, polyacetals, polyketals, polyamides, polyethers, polyesters. Examples of naturally occurring

[1079] polysaccharides that can be used are cellulose, amylose, dextran, dextrin, levan, fucoidan, carraginan, inulin, pectin, amylopectin, glycogen, lixenan, agarose, hyaluronan, chondroitinsulfate, dermatansulfate, keratansulfate, alginic acid and heparin. In yet other exemplary embodiments, the polymer is a copolymer of a polyacetal / polyketal and a hydrophilic polymer selected from the group consisting of polyacrylates, polyvinyl polymers, polyesters, polyorthoesters, polyamides, oligopeptides, polypeptides and derivatives thereof. Exemplary preferred polymeric TTmoieties are PEG, HPMA, PLA, PLGA, PVP, PHF, dextran, oligopeptides, and polypeptides.

[1080] In some aspects of the invention polymeric TTmoieties have a molecular weight ranging from 2 to 200 kDa, from 2 to 100 kDa, from 2 to 80 kDa, from 2 to 60 kDa, from 2 to 40 kDa, from 2 to 20 kDa, from 3 to 15 kDa, from 5 to 10 kDa, from 500 dalton to 5 kDa.

[1081] Other exemplary TTMoieties are dendrimers, such as poly(propylene imine) (PPI) dendrimers, PAMAM dendrimers, and glycol based dendrimers. In a preferred embodiment, the diene comprises an imaging moiety, for example a optical or fluorescent dye, or a radioactive isotope such as18F.

[1082] Preferably, the diene does not comprise a radionuclide.

[1083] It will be understood that chemical modifications may also be made to the tetrazine and the Targeting Agent, in order to make reactions of that compound more convenient for purposes of preparing conjugates of the invention.

[1084] In preferred embodiments, a Targeting Agent, TT, binds to a Primary Target. In order to allow specific targeting of the above-listed Primary Targets, the Targeting Agent TTcan comprise compounds including but not limited to antibodies, antibody derivatives, antibody fragments, antibody (fragment) fusions (e.g. bi-specific and tri-specific mAh fragments or derivatives), proteins, peptides, e.g. octreotide and derivatives, VIP, MSH, LHRH, chemotactic peptides, cell penetrating peptide, membrane translocation moiety, bombesin, elastin, peptide mimetics, organic compounds, inorganic compounds, carbohydrates,

[1085] monosaccharides, oligosacharides, polysaccharides, oligonucleotides, aptamers, viruses, whole cells, phage, drugs, polymers, liposomes, chemotherapeutic agents, receptor agonists and antagonists, cytokines, hormones, steroids, toxins.

[1086] Examples of organic compounds envisaged within the context of the present invention are, or are derived from, dyes, compounds targeting CAIX and PSMA, estrogens, e.g. estradiol, androgens, progestins, corticosteroids, methotrexate, folic acid, and cholesterol.

[1087] According to a particular embodiment of the present invention, the Primary Target is a receptor and a Targeting Agent is employed, which is capable of specific binding to the Primary Target. Suitable Targeting Agents include but are not limited to, the ligand of such a receptor or a part thereof which still binds to the receptor, e.g. a receptor binding peptide in the case of receptor binding protein ligands. Other examples of Targeting Agents of protein nature include insulin, transferrin, fibrinogen-gamma fragment, thrombospondin, claudin, apolipoprotein E, Affibody molecules such as for example ABY-025, Ankyrin repeat proteins, ankyrin-like repeat proteins, interferons, e.g. alpha, beta, and gamma interferon, interleukins, lymphokines, colony stimulating factors and protein growth factor, such as tumor growth factor, e.g. alpha, beta tumor growth factor, platelet- derived growth factor (PDGF), uPAR targeting protein, apolipoprotein, LDL, annexin V, endostatin, and angiostatin. Alternative examples of targeting agents include DNA, RNA, PNA and LNA which are e.g. complementary to the Primary Target.

[1088] Examples of peptides as targeting agents include LHRH receptor targeting peptides, EC-1 peptide, RGD peptides, HER2-targeting peptides, PSMA targeting peptides, somatostatin-targeting peptides, bombesin. Other examples of targeting agents include lipocalins, such as anticalins. One particular embodiment uses Affibodies™ and multimers and derivatives.

[1089] In a preferred embodiment the TTis selected from antibodies and antibody derivatives such as antibody fragments, fragment fusions, proteins, peptides, peptide mimetics, organic molecules, dyes, fluoresencent molecules, and enzyme substrates.

[1090] In a preferred embodiment the TTbeing an organic molecule has a molecular weight of less than 2000 Da, more preferably less than 1500 Da, more preferably less than 1000 Da, even more preferably less than 500 Da.

[1091] In another preferred embodiment the TTis selected from antibody fragments, fragment fusions, and other antibody derivatives that do not contain a Fc domain.

[1092] In another embodiment the TTis a polymer. Typical polymers used in this embodiment include but are not limited to polyethyleneglycol (PEG), poly(A -(2- hydroxypropyl) methacrylamide) (HPMA), polylactic acid (PLA), polylactic-glycolic acid (PLGA), poly glutamic acid (PG), polyvinylpyrrolidone (PVP), poly(l- hydroxymethylethylene hydroxymethyl-formal (PHF). Other examples are copolymers of a polyacetal / polyketal and a hydrophilic polymer selected from the group consisting of polyacrylates, polyvinyl polymers, polyesters, polyorthoesters, polyamides, oligopeptides, polypeptides and derivatives thereof. Other examples are oligopeptides, polypeptides, glycopolysaccharides, and polysaccharides such as dextran and hyaluronan, In addition reference is made to [G. Pasut, F.M.

[1093] Veronese, Prog. Polym. Sci. 2007, 32, 933—961]. In preferred embodiments the TTbeing a polymer accumulates at the Primary Target by virtue of the EPR effect. According to a further particular embodiment of the invention, the

[1094] Primary Target and Targeting Agent are selected so as to result in the specific or increased targeting of a tissue or disease, such as cancer, an inflammation, an infection, a cardiovascular disease, e.g. thrombus, atherosclerotic lesion, hypoxic site, e.g. stroke, tumor, cardiovascular disorder, brain disorder, apoptosis, angiogenesis, an organ, and reporter gene / enzyme. This can be achieved by selecting Primary Targets with tissue-, cell- or disease- specific expression. For example, the CC49 antibody targets TAG72, the expression of which is limited in normal tissues, but receptors are overexpressed in various solid tumor cell types.

[1095] As used herein, a TTthat "specifically binds or complexes with" or "targets" a cell surface molecule, an extracellular matrix target, or another target, preferentially associates with the target via intermolecular forces. For example, the ligand can preferentially associate with the target with a dissociation constant (Kdor KD) of less than about 50 nM, less than about 5 nM, or less than about 500 pM.

[1096] In another embodiment the targeting agent TTlocalizes in the target tissue by means of the EPR effect. An exemplary TTfor use in with the EPR effect is a polymer.

[1097] In preferred embodiments the targeting agent TTlocalizes or has retention in a particular system, tissue, or organ in the body, for example, blood

[1098] circulation, lymphatic system, the nervous system, the digestion system, RES system, or organs such as the heart or kidney. For example, microparticles will localize in the liver, large hydrophilic polymers will have retention in circulation. Likewise, use of an albumin binding moiety as TTwill result in prolonged retention in circulation.

[1099] In preferred embodiments, TTis used to modify the pharmacokinetics of the moiety it is attached to. This can include, but is not limited to, delaying the blood clearance of said moiety, affecting the volume of distribution of said moiety (e.g. reducing or increasing the volume of distribution), affecting the metabolism of said moiety, and / or affecting (preferably avoiding) the sticking or uptake of said moiety to non-target tissues. Exemplary TT's in this regard are polymer, peptide, peptoid, dendrimer, protein, carbohydrate, oligonucleotide, oligosaccharide, lipid, liposome, micelle, nanoparticle, microparticle, albumin, albumin-binding moiety, and small to medium sized organic molecules such as steroids and dyes. Typically, a suitable polymer is polyethyleneglycol (PEG) or polyp ropyleneglycol (PPG). Such suitable PEG includes PEG with a number of repeating units in a range of from 2 to 4000, and PEG with a molecular weight in a range of from 200 Da to 100,000 Da.

[1100] In preferred embodiments, when a TTis an Administration Agent, it equals CB.

[1101] R32

[1102] R32is a conjugation moiety, which is a chemical group that can be used for binding, conjugation or coupling to e.g. a Label, Administration Agent, Construct C, R98, La, Lb, Sl, SP, and LC. The person skilled in the art is aware of the myriad of strategies that are available for the chemoselective or -unselective or

[1103] enzymatic coupling or conjugation of one molecule or construct to another.

[1104] In preferred embodiments, R32is a moiety that allows conjugation to a protein comprising natural and / or non-natural amino acids. Moieties suitable for conjugation are known to the skilled person. Conjugation strategies are for example found in [O. Boutureira, G.J.L. Bernardes, Chem. Rev., 2015, 115, 2174- 2195]

[1105] In particularly favourable embodiments, R32is selected from the group consisting of N-maleimidyl groups, halogenated N-alkylamido groups,

[1106] sulfonyloxy N-alkylamido groups, vinyl sulfone groups, activated carboxylic acids, benzenesulfonyl halides, ester groups, carbonate groups, sulfonyl halide groups, thiol groups or derivatives thereof, C2-6alkenyl groups, C2-6alkynyl groups, C7- 18cycloalkynyl groups, C5- 18heterocycloalkynyl groups, bicyclo[6.1.0]non-4-yn-9-yl] groups, C3- 12cycloalkenyl groups, azido groups, phosphine groups, nitrile oxide groups, nitrone groups, nitrile imine groups, isonitrile groups, diazo groups, ketone groups, (O-alkyl)hydroxylamino groups, hydrazine groups, halogenated N- maleimidyl groups , aryloxymaleimides, dithiophenolmaleimides, bromo- and dibromopyridazinediones, 2,5-dibromohexanediamide groups, alkynone groups, 3- arylpropiolonitrile groups, l,l-bis(sulfonylmethyl)-methylcarbonyl groups or elimination derivatives thereof, carbonyl halide groups, allenamide groups, 1,2- quinone groups, isocyanate groups, isothiocyanate groups, aldehyde groups, triazine groups, squaric acids, 2-imino-2-methoxyethyl groups, (oxa)norbornene groups, (imino)sydnones, methylsulfonyl phenyloxadiazole groups, aminooxy groups, 2-amino benzamidoxime groups, ethynylphosphonamidates, groups reactive in the Pictet- Spengler ligation and hydrazino- Pictet- Spengler (HIPS) ligation, DNA intercalator, tetrazine groups, and photocrosslinkers.

[1107] In preferred embodiments, R32is an N-maleimidyl group connected to the remaining part of the compound according to Formula (20) via the N atom of the N-maleimidyl group. In other preferred embodiments R32is selected from the group consisting of, hydroxyl groups, amine groups, halogens, vinyl pyridine groups, disulfide groups, pyridyl disulfide groups, sulfonyloxy groups,

[1108] mercaptoacetamide groups, anhydride groups, sulfonylated hydroxyacetamido groups, sulfonyl chlorides, thiosemicarbazone, hydrazine carboxylate, and arylhydrazide.

[1109] In other embodiments R32is group that can be connected to another group by means of an enzyme, for example sortase or Tubulin tyrosine ligase. R’

[1110] In preferred embodiments, each R’ is independently selected from the group consisting of hydrogenC,1-C6alkylene groups, C2-C6alkenylene groups, C2-C6alkynylene groups, C6arylene, C4-C5heteroarylene, C3-C6cycloalkylene groups, C5-C8cycloalkenylene groups, C5-C12alkyl(hetero)arylene groups, C5-C12

[1111] (hetero)arylalkylene groups, C4-C12alkylcycloalkylene groups, and C4-C12cycloalkylalkylene groups.

[1112] In preferred embodiments, each R’ is independently selected from the group consisting of hydrogenC,1-C4alkylene groups, C2-C4alkenylene groups, C2- C4alkynylene groups, C6arylene, C4-C5heteroarylene, C3-C6cycloalkylene groups, C5-C8cycloalkenylene groups, C5-C8alkyl (hetero) arylene groups, C5-C8(hetero)arylalkylene groups, C4-C12alkylcycloalkylene groups, and C4-C8cycloalkylalkylene groups. Unless stated otherwise, for R’ the alkylene groups, alkenylene groups, alkynylene groups, (hetero)arylene groups, cycloalkylene groups, cycloalkenylene groups, alkyl(hetero)arylene groups, (hetero)arylalkylene groups,

[1113] alkylcycloalkylene groups, cycloalkylalkylene groups are optionally substituted with a moiety selected from the group consisting of -Cl, -F, -Br, -I, -OH, -NH2, =O, -SH , -SO3H, -PO3H, -PO4H2, -NO2, and optionally contain one or more

[1114] heteroatoms selected from the group consisting of -O-, -S-, -NH-, -P-, and -Si, wherein the N, S, and P atoms are optionally oxidized.

[1115] Medical use and non-therapeutic methods

[1116] Therapeutic use

[1117] In one aspect, the invention relates to a compound, a combination, or a kit of the invention for use as a medicament. Alternatively, the kits of the invention are used in a method for treating or imaging patients, said method comprising administering the compounds comprised in the kits of the invention to a subject.

[1118] In another aspect, the invention pertains to a compound, a

[1119] combination, or a kit of the invention for use in the treatment of a disease, preferably cancer, in a subject, preferably a human. Preferably, the treatment is radiotherapy.

[1120] Preferably, the radiotherapy comprises the steps of

[1121] (a) administering a compound according to Formula (1) as defined herein, to the subject;

[1122] (b) administering a Cleaving Agent as defined herein, to said subject;

[1123] (c) irradiating the compound according to Formula (1) present in the subject.

[1124] The disclosure also pertains to a method of treatment in a subject as defined herein, said method comprising the steps (a)-(c) as defined in the preceding paragraph. Preferably, the method is for treating cancer in said subject.

[1125] In a preferred embodiment, step (a) is carried out first, secondly step (b) is carried out, and then step (c). In that embodiment, preferably step (b) is carried out after waiting a sufficient amount of time after step (a), so that a significant part, preferably at least 10%, more preferably at least 50 % of what is maximally achievable, of the dose of a compound according to Formula (1) has reached the target. Preferably, the Cleaving Agent and / or its dose are chosen in this embodiment so as to ensure that compound according to Formula (1) that has reached the target is not cleaved in significant amounts, preferably less than 30 % , more preferably less than 10%. In such a way, in step (b) the target-to- background ratio of the radionuclide can be optimized before irradiation in step (c). Preferably, in this embodiment a further step (b) is carried out after step (c) so as to quickly reduce the amount of radionuclides in the subject after

[1126] irradiation.

[1127] In another embodiment, step (a) is carried out first, secondly step (c) is carried out, and then step (b). In this way, the amount of radionuclides in the subject can be quickly reduced after irradiation to minimize the radiation dose received by non-target tissues.

[1128] In another embodiment, step (b) is carried out first, allowing the Cleaving Agent to accumulate in non-target tissue that needs protecting from the radiation; secondly step (a) is carried out, affording the targeting of the radiation to target tissue, while the Label is cleaved and removed in non-target tissue by the pre-localized Cleaving Agent; and then step (c) takes place.

[1129] Likewise, the Cleaving Agent can be locally administered, i.e. directly injected, into tissues that need protecting, as opposed to a systemic intravenous administration.

[1130] One prominent application of the invention, is radioimmunotherapy targeted to an internalizing cancer receptor such as HER2. In this approach the HER2-targeting antibody Trastuzumab (Tmab) is modified with, for example three TCO-chelate constructs as shown below. The TCO-chelate construct (NHS- TCO-DOTA) comprises an active ester for lysine conjugation, the TCO linker, and a DOTA chelate for117Lu labeling, a therapeutic beta emitter. Following117Lu- labeling of Tmab and intravenous (i.v.) injection, the117Lu-Tmab is allowed to circulate, bind the HER2 target on the breast cancer or ovarian cancer sites, allowed time to internalize (ca 2 days) after which the tetrazine comprising Cleaving Agent is intravenously injected, which cleaves117Lu-DOTA construct from the freely circulating Tmab, resulting in rapid clearance of117Lu-DOTA construct via the kidney, and a vast reduction of radiation dose to the bone marrow. Typically the Cleaving Agent is hydrophilic and as a result non cell permeable and will therefore not cleave the117Lu-Tmab inside the target cell. However, even if the Cleaving Agent is cell permeable and cleaves117Lu-Tmab inside the target cell, typically the released117Lu-DOTA will remain trapped inside the cell.

[1131]

[1132] Also non-internalizing cancer receptors can be used as Primary Targets in above examples if the Cleaving Agent is designed to have a low or slow uptake in the tumor. For example, the Cleaving Agent can comprise a biodegradable PLGA particle core of ca 500 nm diameter, modified with tetrazine moieties. Such a particle will exhibit rapid clearance from blood by the liver, ensuring that it can only react with TCO containing constructs in circulation, and does not

[1133] accumulate in the tumor, as previously shown for tetrazine clearing agents

[1134] [Rossin et al., J. Nucl. Med. 2013, 4, 11, 1989-1995; and WO2012085789A1] For imaging applications, slow accumulation at the target site may be acceptable, in which case the tetrazine can be modified with an albumin binding moiety, or a protein or a polymer such as a PEG, maximizing its retention in circulation, and thereby facilitating its reaction with TCO constructs in circulation.

[1135] In one other preferred embodiment of this invention, the administration of the compound of Formula (1) followed by the Cleaving agent allows to tune the blood circulation and excretion pathway of the released Label. In the context of117Lu-Tmab RIT , after cell internalization a Cleaving Agent comprising, for example, a tetrazine functionalized with a short

[1136] poly ethyleneglycol (PEG) polymer is injected and binds the TCO Trigger, resulting in the cleavage of the bond between the TCO and the antibody.

[1137] Subsequently the177Lu-DOTA chelate carrying the PEG is released in circulation and due to the PEG it clears via the kidneys.

[1138]

[1139] In a similar approach, instead of a linear or branched polymer the Cleaving Agent carries one or more functional groups that influence the clearance pathway of the released moiety. For instance, a Cleaving Agent comprising a tetrazine and several galactose groups will produce a released moiety that binds the Ashwell receptor in hepatocytes, therefore resulting in fast hepatobiliary clearance of the label.

[1140] In another preferred embodiment of this invention, the Administration Agent is an antibody fragment carrying an imageable or therapeutic radiometal chelate that accumulates specifically in a tumor or another diseased tissue and internalizes into target cells, but is also non- specifically retained in non-target organs such as, but not restricted to, kidneys, salivary glands and lacrimal glands. In this approach the Label (e.g.177Lu or225Ac labeled DOTA or89Zr labeled DFO) is linked to the targeting moiety via a TCO trigger. After i.v.

[1141] injection of the compound of Formula (1) and after such Agent has accumulated in the diseased tissue and internalized into target cells (e.g. 4 to 24h post- injection), the patient in administered a Cleaving Agent intravenously. The Cleaving Agent specifically binds the TCO trigger on the Administration Agent in non-target organs and releases the Label thus inducing radioactivity wash out from these organs via the urine. This reduces the radioactive dose delivered to non-target organs thus increasing the therapeutic index of Administration Agents object of this invention and reducing the chance of toxic side effects for the patient in nuclear imaging procedures.

[1142] In another preferred embodiment of this invention the compound of Formula (1) is functionalized on both allylic positions. The compound of Formula (l)is injected i.v. in an animal or human subject and is followed, after a suitable time (e.g. 2 days), by i.v. injection of the Cleaving Agent which specifically reacts with the Trigger resulting in the release of at least one of the two moieties conjugated in TCO allylic position. This approach allows the very fast and complete release of a small fragment (e.g. a Label) that will rapidly clear from non target tissues, preferentially via the kidney, regardless of the pyridazine tautomer (either the 1,4 or 2,5) formed after reaction of the TCO Trigger and the tetrazine Cleaving Agent. For very fast and complete release it is preferred that the tetrazine is according to Formula (14), with Yabeing Y1, Y3, or Y5with Q1being X45, preferably X45being OH, and Yb being identical to Yaor H. One non limiting example of this approach is shown below for a177Lu-labeled mAb

[1143]

[1144] In yet another preferred embodiment of this invention the compound of Formula (1) comprises a TCO Trigger conjugated Targeting Agent and to an imaging or therapeutic moiety (Label) via a self-immolative linker. The compound of Formula (1) is injected i.v. in an animal or human subject, it accumulates at the target site and, after a suitable time (e.g. one or two days) is followed by i.v. injection of a tetrazine Cleaving Agent. The tetrazine reacts with the Trigger resulting in an intermediate that rearranges electronically resulting in the fragmentation of the linker and the detachment of the Label from the Targeting Agent. As a result the Label, being a small molecule, rapidly clears from the subject's circulation, preferentially via the kidney. A non limiting example of this invention is shown below

[1145]

[1146] In one other preferred embodiment of this invention the compound of Formula (1) comprises an imageable or therapeutic moiety bound via a TCO Trigger to a Targeting Agent that binds a specific receptor or molecule present both at a disease site and in circulation due to shedding. Non limiting examples of shedding targets are the carcinoembryonic antigen (CEA), the prostate specific antigen (PSA), and the tumor necrosis factor a (TNF-a) receptor. In the presence of target shedding, Administration Agent binding to circulating target is detrimental as it causes loss of image contrast and / or toxic side effects in the subject of the medical intervention. With the approach of this invention, the compound of Formula (1) is injected i.v. in an animal or human subject and binds to its target at the disease site and in circulation. After a suitable time (one or two days) the subject is injected the tetrazine Cleaving Agent i.v. which is designed to specifically react with the TCO Trigger on the circulating (bound) Administration Agent. Upon reaction between the tetrazine and the TCO, the imageable or therapeutic moiety is released from the Administration Agent and it clears rapidly from circulation.

[1147] In one preferred embodiment, the invention is used to reduce the kidney dose instead of the bone marrow dose. In this embodiment, the Administration Agent being an intact IgG antibody is labeled with225Ac and allowed to bind its Primary Target, such as HER2, PSMA.225Ac has a chain of daughter isotopes, and upon the 1stdecay of225Ac, the nuclide is separated from the DOTA and the Administration Agent resulting in renal uptake of the free daughter221Fr. Timely injection of the Cleaving Agent results cleavage in blood and rapid elimination of DOTA-225Ac via the kidneys and reduced221Fr radiation dose to the kidneys.

[1148] In another embodiment, the Primary Target is a receptor on a blood cancer cell, i.e. CD33 on AML cells, and the Administration Agent is antiCD33 mAh, and the Label is DOTA-225Ac. After CD33 binding and internalization, the DOTA-225Ac Label of the freely circulating mAh in cleaved to reduce the radiation toxicity to kidneys, and also the bone marrow, liver, and spleen.

[1149] Furthermore, the disclosure pertains to a diagnostic method comprising the steps of

[1150] (a) administering a compound according to Formula (1) as defined herein, to a subject, preferably a human;

[1151] (b) administering a Cleaving Agent as defined herein, to said subject;

[1152] (c) imaging the compound according to Formula (1) present in the subject to collect data;

[1153] (d) comparing said data to standard values;

[1154] (e) finding a significant deviation from said standard values during comparison;

[1155] (f) attributing the significant deviation to a particular clinical picture, preferably to cancer.

[1156] Diagnostic method

[1157] The invention also pertains to a compound of Formula (1) as defined herein, a combination as defined herein, or a kit as defined herein for use in a diagnostic method comprising the steps of

[1158] (a) administering a compound according to Formula (1) as defined herein, to a subject, preferably a human;

[1159] (b) administering a Cleaving Agent as defined herein, to said subject;

[1160] (c) imaging the compound according to Formula (1) present in the subject to collect data;

[1161] (d) comparing said data to standard values;

[1162] (e) finding a significant deviation from said standard values during comparison; (f) attributing the significant deviation to a particular clinical picture, preferably to cancer.

[1163] Non-therapeutic method

[1164] The invention also pertains to a non-therapeutic method for imaging a compound of Formula (1) as defined herein, in a subject as defined herein, preferably a human, said non-therapeutic method comprising the steps of

[1165] (a) administering a compound according to Formula (1) as defined herein, to the subject;

[1166] (b) administering a Cleaving Agent as defined herein, to said subject;

[1167] (c) imaging the compound according to Formula (1) present in the subject.

[1168] In a preferred embodiment, step (a) is carried out first, secondly step (b) is carried out, and then step (c). In that embodiment, preferably step (b) is carried out after waiting a sufficient amount of time after step (a), so that a significant part, preferably at least 10%, more preferably at least 50 % of what is maximally achievable, of the of the initial dose of a compound according to Formula (1) has reached the target. Preferably, the Cleaving Agent and / or its dose are chosen in this embodiment so as to ensure that compound according to Formula (1) that has reached the target is not cleaved in significant amounts, preferably less than 30 %, more preferably less than 10%. In such a way, in step (b) the target-to- background ratio of the radionuclide can be optimized before imaging in step (c).

[1169] Preferably, in this embodiment a further step (b) is carried out after step (c) so as to quickly reduce the amount of radionuclides in the subject after imaging.

[1170] In another embodiment, step (a) is carried out first, secondly step (c) is carried out, and then step (b). In this way, the amount of radionuclides in the subject can be quickly reduced after imaging, to reduce whole body radiation dose and / or optionally to allow for another imaging procedure (image cycling).

[1171] In another embodiment, step (b) is carried out first, allowing the Cleaving Agent to accumulate in non-target tissue that needs protecting from the radiation or that would otherwise obscure imaging of the Primary Target; secondly step (a) is carried out, affording the targeting of the radiation to target tissue, while the Label is cleaved and removed in non-target tissue by the pre-localized Cleaving Agent; and then step (c) takes place.

[1172] Likewise, the Cleaving Agent can be locally administered, i.e. directly injected, into selected non-target tissues, as opposed to a systemic i.v.

[1173] administration.

[1174] The invention can be used to improve radioimmunoimaging of HER2 with Trastuzumab (Tmab). In this approach Tmab is modified with for example 2 TCO-DFO chelate constructs, as shown below, wherein the Tmab is conjugated via thiol maleimide chemistry. Following89Zr-labeling of Tmab and intravenous (i.v.) injection, the89Zr -Tmab is allowed to circulate, bind the HER2 target on the breast cancer or ovarian cancer sites, allowed time to internalize (ca 2 days) after which the tetrazine comprising Cleaving Agent is i.v. injected, which cleaves the89Zr -DFO label from the freely circulating Tmab, resulting in rapid clearance of89Zr -DFO construct via the kidney, and a vast improvement tumor- blood ratio in imaging of the target.

[1175]

[1176] In a similar approach as with the above HER2 imaging example, the invention can be used in companion imaging of antibody drugs that are being developed to cross the blood brain barrier (BBB) to treat, for example, Alzheimer's disease. In such an approach the therapeutic antibody can be modified with an additional domain which binds to the transferrin receptor, resulting in crossing of the BBB. As only a minor amount will cross the BBB and bind to its Primary Target, and as a large amount will still freely circulate in blood, conventional imaging approaches (e.g. by labeling the antibody with89Zr) is hampered by very poor target-non-target (T-NT) ratios. Conjugation of the cleavable DFO-TCO- maleimide construct shown above to the anti-Alzheimer antibody, labeling with89Zr, i.v. injection, followed by some time for target uptake will allow the cleavage of freely circulating89Zr-antibody at desired time points, making the circulating antibody essentially invisible, while retaining the89Zr-signal at the target site, boosting T-NT ratios. This approach also allows discriminating between89Zr-antibody that has crossed the BBB and the portion that has bound in the brain but has not crossed the BBB, or where the BBB is impaired. In this embodiment, the diene is preferably designed such that it does extravasate, but does not significantly permeate the BBB. In another preferred embodiment, the diene is designed such that it does not extravasate into other tissues.

[1177] Administration

[1178] When administering the compound of Formula (1) and the Cleaving Agent to a subject, such as an animal or human, in preferred embodiments the compound of Formula (1) is administered first. It will take a certain time period before the the compound of Formula (1) has reached the Primary Target, and optionally internalized in the cell or crossed the blood brain barrier. This time period may differ from one application to the other and may be for example minutes or hours.

[1179] After the time period of choice has elapsed, the Cleaving Agent is administered, which reacts with the the compound of Formula (1) to decouple the Administration Agent and the Label, preferably in the non-target tissues. In some preferred embodiments, the time interval between the administration of the compound of Formula (1) and the Cleaving Agent is between 10 minutes and 4 weeks. In some preferred embodiments, the time interval between the

[1180] administration of the compound of Formula (1) and the Cleaving Agent is between 1 hour and 2 weeks, preferably between 1 and 168 hours, more

[1181] preferably between 1 and 120 hours, even more preferably between 1 and 96 hours, more preferably between 3 and 72 hours, more preferably still between 4 and 48 hours, and most preferably between 5 and 24 hours.

[1182] The compounds and the combinations of the invention can be administered via different routes including but not limited to intravenous or subcutaneous injection, intraperitoneal, local injection, oral administration, rectal

[1183] administration and inhalation. Formulations suitable for these different types of administrations are known to the skilled person. Compounds of Formula (1) or Cleaving Agents according to the invention can be administered together with a pharmaceutically acceptable carrier. A suitable pharmaceutical carrier as used herein relates to a carrier suitable for medical or veterinary purposes, not being toxic or otherwise unacceptable. Such carriers are well known in the art and include for example saline, buffered saline, dextrose, water, glycerol, ethanol, and combinations thereof. The formulation should suit the mode of administration.

[1184] It will be understood that the chemical entities administered, viz. the compound of Formula (1) and the Cleaving Agent, can be in a modified form that does not alter the chemical functionality of said chemical entity, such as salts, hydrates, or solvates thereof.

[1185] In preferred embodiments, the Cleaving Agent, preferably comprising a Targeting Agent, is administered first, and thereafter the compound of Formula (1) is administered.

[1186] Preferably, in embodiments where the compound of Formula (1) and the Cleaving Agent are administered approximately simultaneously, they are administered via different routes.

[1187] Subject

[1188] As used herein,“subject” means any animal, preferably a mammal, most preferably a human. The term“mammal” as used herein, encompasses any mammal. Examples of mammals include, but are not limited to, cows, horses, sheep, pigs, cats, dogs, mice, rats, rabbits, guinea pigs, non-human primates (NHPs) such as monkeys or apes, humans, etc., more preferably a human. Non-therapeutic use

[1189] The invention also pertains to a use of a compound of Formula (1) as defined herein, a combination as defined herein, or a kit as defined herein, for imaging in a subject, preferably a human.

[1190] Examples General methods

[1191] All reagents, chemicals, materials and solvents were obtained from commercial sources and were used as received, including nitrile starting compounds that not have been described. All solvents were of AR quality. Sodium [125I]iodide, [111In]Indium and [177Lu]lutetium chloride, and [89Zr] zirconium oxalate solutions were purchased from PerkinElmer, Curium and IDB. Zeba desalting spin columns (7 and 40 kDa MW cut-off, 0.5 mL) and Slide-A-Lyzer dialysis cassettes (20 kDa MW cut-off) were purchased from Pierce Protein Research (Thermo Fisher Scientific). Mouse plasma was purchased from Innovative Research. 29-Amino- 3,6,9,12,15,18,21,24,27-nonaoxanonacosan-l-ol was purchased from PurePEG. 3,6-Dimethyl- 1,2, 4, 5-tetrazine and (E)-cyclooct-2-en-l-yl (4-nitrophenyl) carbonate were prepared according to literature procedures [Versteegen et ah, Angew. Chem. Int. Ed. 2013, 52, 14112—14116]. Analytical thin layer chromatography was performed on Kieselgel F-254 precoated silica plates. Column chromatography was carried out on Screening Devices B.V. silica gel (flash: 40-63 pm mesh and normal: 60-200 pm mesh).1H-NMR and13C-NMR spectra were recorded on a Bruker Avance III HD (400 MHz for1H -NMR and 100 MHz for13C-NMR) spectrometer at 298 K. Chemical shifts are reported in ppm downfield from TMS at rt. Abbreviations used for splitting patterns are s = singlet, d = doublet, dd = double doublet, t = triplet, q = quartet, m = multiplet and br = broad. HPLC-PDA / MS was performed using a Shimadzu LC-10 AD VP series HPLC coupled to a diode array detector (Finnigan Surveyor PDA Plus detector, Thermo Electron Corporation) and an Ion-Trap (LCQ Fleet, Thermo Scientific). HPLC-analyses were performed using a Alltech Alltima HP C1s 3p column using an injection volume of 1-4 mL , a flow rate of 0.2 mL min-1and typically a gradient (5 % to 100 % in 10 min, held at 100 % for a further 3 min) of MeCN in H2O (both containing 0.1 % formic acid) at 298 K. Size exclusion chromatography (SEC) was performed on an Akta system (GE Healthcare Life Science) equipped with a Superdex200 column. Radio-HPLC was performed on an Agilent 1100 system, equipped with a Gabi radioactive detector (Raytest). The samples were loaded on an AlltimaC18 column (4.6 x 150mm, 5m), which was eluted at 1 mL min-1 with a linear gradient o...

Claims

AMENDED CLAIMSreceived by the International Bureau on 26 October 2020 (26.10.2020)1. A compound satisfying Formula (1):Formula (1);and pharmaceutically acceptable salts thereof, whereinthe compound of Formula (1) comprises at least one Label and at least oneAdministration Agent;the Label is a moiety comprising a radionuclide;the Administration Agent is an antibody;each X1, X2, X3, X4is independently selected from the group consisting of -C(R47)2-, -NR37-, -C(O)-, -O-, such that at most two of X1, X2, X3, X4are not -C(R47)2-, and with the proviso that no sets consisting of adjacent atoms are present selected from the group consisting of -O-O-, -O-N-, -C(O)-O-, N-N-, and -C(O)-C(O)-;X5is -C(R47)2- or -CHR48, preferably X5is -C(R47)2-;each R48is independently selected from the group consisting of -LB, and -LA; preferably R48is -LB;R48is bound to the remainder of the compound of Formula (1) via a part of R48that is -O-, -S-, -OC(O)-, -OC(S)-, -SC(O)-, or -SC(S)-;LBis a moiety satisfying Formula (2):Formula (2); whereinthe dashed line denotes a bond to the remainder of the compound of Formula (1); SLis a hnker, which optionally is a self-immolative linker LC;each R98individually is the Label or a clearance-directing group;each d independently is 0 or 1;e is an integer in a range of from 0 to 4, preferably e is 0;LAis a moiety satisfying Formula (3):Formula (3); whereinthe dashed line denotes a bond to the remainder of the compound of Formula (1); each s is independently 0 or 1; preferably each s is 0;i is an integer in a range of from 0 to 4, preferably 0 or 1, most preferably 0;each SPindependently is a spacer, which optionally is a self-immolative linker LC; AAdenotes the Administration Agent;CCdenotes a Construct-C, wherein each Construct-C is independently selected from the group consisting of the Label and the Administration Agent; preferably the compound of Formula (1) comprises at most one CC;provided that LAonly comprises both the Label and the Administration Agent when LAis R48;provided that if LAbeing R48comprises both the Label and the Administration Agent, then the SPlinked to said Label and said Administration Agent is a self- immolative hnker;each R47is independently selected from the group consisting ofhydrogen, -Lp, -LA, -(SP)i-CC, -F, -Cl, -Br, -I, -OR37, -N(R37)2, -SO3, -PO3-, -NO2, - CF3, -SR37, S(=O)2N(R37)2, OC(=O)R37, SC(=O) R37, OC(=S)R37, SC(=S)R37, NR37C(=O)-R37, NR37C(=S)-R37, NR37C(=O)O-R37, NR37C(=S)O-R37,NR37C(=O)S-R37, NR37C(=S)S-R37, OC(=O)N(R37)2, SC(=O)N(R37)2,OC(=S)N(R37)2, SC(=S)N(R37)2, NR37C(=O)N(R37)2, NR37C(=S)N(R37)2, C(=O)R37,C(=S)R37,C(=O)N(R37)2, C(=S)N(R37)2, C(=O)O-R37, C(=O)S-R37, C(=S)O-R37, C(=S)S-R37, S(O)R37, -S(O)2R37, NR37S(O)2R37, -ON(R37)2.NR37OR37, C1-C24alkyl groups, C2-C24alkenyl groups, C2-C24alkynyl groups, C6-C24aryl groups, C2-C24heteroaryl groups, C3-C24cycloalkyl groups, C5-C24cycloalkenyl groups, C12-C24cycloalkynyl groups, C3-C24(cyclo) alkyl (hetero) aryl groups, C3-C24(hetero)aryl(cyclo)alkyl, C4-C24(cyclo)alkenyl(hetero)aryl groups, C4-C24(hetero)aryl(cyclo)alkenyl groups, C4-C24(cyclo)alkynyl(hetero)aryl groups, C4- C24(hetero)aryl(cyclo)alkynyl groups, C4-C24alkylcyclo alkyl groups, and C4-C24cyclo alkylalkyl groups; wherein i is an integer in a range of from 0 to 4, preferably i is an integer ranging from 0 to 1,wherein the alkyl groups, alkenyl groups, alkynyl groups, aryl, heteroaryl, cycloalkyl groups, cycloalkenyl groups, cycloalkynyl groups,(cyclo)alkyl(hetero)aryl groups, (hetero)aryl(cyclo)alkyl groups,(cyclo)alkenyl(hetero)aryl groups, (hetero) aryl (cyclo) alkenyl groups,(cyclo)alkynyl(hetero)aryl groups, (hetero) aryl (cyclo) alkynyl groups,alkylcycloalkyl groups, cycloalkylalkyl groups are optionally substituted with a moiety selected from the group consisting of -Cl, -F, -Br, -I, -OR37, -N(R37)2, - SO3R37, -PO3(R37)2, -PO4(R37)2, -NO2, -CF3, =O, =NR37, and -SR37, and optionally contain one or more heteroatoms selected from the group consisting of O, S, NR37, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized;two R47and / or R37are optionally comprised in a ring,two R47and / or R37are optionally comprised in a ring so as to form a ring fused to the eight membered trans-ring of Formula (1); each R37is independently selected from the group consisting of hydrogen, -LB, - LA, -(SP)i-CC, C1-C24alkyl groups, C2-C24alkenyl groups, C2-C24alkynyl groups, C6-C24aryl groups, C2-C24heteroaryl groups, C3-C24cycloalkyl groups, C5-C24cycloalkenyl groups, C12-C24cycloalkynyl groups, C3-C24(cyclo)alkyl(hetero)aryl groups, C3-C24(hetero)aryl(cyclo)alkyl, C4-C24(cyclo) alkenyl (hetero) aryl groups, C4-C24(hetero) aryl (cyclo) alkenyl groups, C4-C24(cyclo) alkynyl (hetero) aryl groups, C4-C24(hetero) aryl (cyclo) alkynyl groups, C4-C24alkylcycloalkyl groups, and C4- C24cycloalkylalkyl groups; wherein i is an integer in a range of from 0 to 4, preferably i is 1;the R37groups not being hydrogen are optionally substituted with a moietyselectedfromthegroupconsistingof-Cl,-F,-Br,-I,-OH,-NH2,-SO3H,-PO3H,-PO4H2,-NO2,-CF3,=O,=NH,and-SH,andoptionallycontainoneormoreheteroatomsselectedfromthegroupconsistingofO,S,NH,P,andSi,whereintheN,S,andPatomsareoptionallyoxidized,whereintheNatomsareoptionallyquaternized.

2. Thecompoundaccordingtoclaim 1,whereintheradionuclideisselectedfromthegroupconsistingof3H,11C,13N,15O,18F,19F,51Cr,52Fe,52Mn,55Co,60Cu,81Cu,62Zn,82Cu,63Zn,84Cu,88Ga,67Ga,68Ga,70As,71As,72As,74As,75Se,75Br,76Br,77Br,8OBr,82Br,82Rb,86Y,88Y,90Y,89Sr,89Zr,97Ru,99mTc,110In,min,113In,114In,117Sn,120I,122Xe,123I,124I,125I,166Ho ,167Tm,169Yb,193Pt,195Pt,201Tl,203Pb,24Na,32P,33P,47Sc,59Fe,67Cu,78As,77As,89Br,82Br,89Sr, "Nb, "Y,i03Ru,105Rh,i09Pd,111Ag,111In,121Sn,127Te,131I,140La,141Ce,142Pr,143Pr,144Pr,149Pm,149Tb,151Pm,133Sm,139Gd,161Tb,165Dy,166Dy,166Ho,169Er,172Tm,lTOYb,177Lu,186Re,188Re,198Au,199Au,211At,211Bi,212Bi,212Pb,213Bi,214Bi,223Ra,224Ra,225Ac and227Th.

3. Thecompoundaccordingtoanyoneoftheprecedingclaims,whereintheLabelisachelatingmoietythatchelatestheradionuclide.

4. Thecompoundaccordingtoanyoneoftheprecedingclaims,whereinX1, X2,X3,andX4are-C(R47)2-,andpreferablyatmostfourR47,morepreferablyatmosttwoR47,arenotH.

5. Thecompoundaccordingtoanyoneoftheprecedingclaims,whichcomprisesatmostoneLabelandatmostoneAdministrationAgent.

6. Acombinationcomprisingthecompoundaccordingtoanyoneoftheprecedingclaims,andaCleavingAgent,withtheprovisothatwhenatleastoneR48inFormula(1)comprisesaLabel,thentheCleavingAgentdoesnotcomprisethesameLabelasR48;withtheprovisothatwhenatleastoneR48inFormula(1)comprisesanAdministrationAgent,thentheCleavingAgentdoesnotcomprisethe same Administration Agent as R48;wherein the Cleaving Agent is a diene.

7. The combination according to claim 6, wherein the diene is a tetrazine, preferably a tetrazine satisfying Formula (4) and preferably includingpharmaceutically accepted salts thereof:Formula (4) wherein each moiety Q1and Q2is independently selected from the group consisting of hydrogen, -F, -Cl, -Br, -I, -OR37, -N(R37)2, -SO3, -PO3·, -NO2, -CF3, -SR37,S(=O)2N(R37)2, OC(=O)R37, SC(=O) R37, OC(=S)R37, SC(=S)R37, NR37C(=O)-R37,NR37C(=S)-R37, NR37C(=O)O-R37, NR37C(=S)O-R37, NR37C(=O)S-R37, NR37C(=S)S- R37, OC(=O)N(R37)2, SC(=O)N(R37)2, OC(=S)N(R37)2, SC(=S)N(R37)2,NR37C(=O)N(R37)2, NR37C(=S)N(R37)2, C(=O)R37,C(=S)R37,C(=O)N(R37)2,C(=S)N(R37)2, C(=O)O-R37, C(=O)S-R37, C(=S)O-R37, C(=S)S-R37, S(O)R37, - S(O)2R37, NR37S(O)2R37, -ON(R37)2, .NR37OR37, alkyl groups, alkenyl groups, alkynyl groups, aryl groups, heteroaryl groups, cycloalkyl groups, cycloalkenyl groups, cycloalkynyl groups, (cyclo)alkyl(hetero)aryl groups,(hetero)aryl(cyclo)alkyl, (cyclo)alkenyl(hetero)aryl groups,(hetero)aryl(cyclo)alkenyl groups, (cyclo)alkynyl(hetero)aryl groups,(hetero)aryl(cyclo)alkynyl groups, alky Icy clo alkyl groups, and cycloalkylalkyl groups;wherein the Q1and Q2groups not being H, -F, -Cl, -Br, -I, -OH, -NH2, -SO3, -PO3 ,-NO2, -CF3, are optionally substituted, preferably with a moiety selected from the group consisting of -Cl, -F, -Br, -I, -OR37, -N(R37)2, -SO3R37, -P03(R37)2, -PO4(R37k - NO2, -CF3, =O, =NR37, and -SR37, and optionally contain one or more heteroatoms selected from the group consisting of O, S, NR37, P, and Si, wherein the N, S, and P atoms are optionally oxidized, wherein the N atoms are optionally quaternized, wherein the Q1and Q2groups are optionally bound to a polymer, a particle, a peptide, a peptoid, a dendrimer, a protein, an aptamer, a carbohydrate, anoligonucleotide, an oligosaccharide, a lipid, a steroid, a liposome, a Targeting Agent TT, -(SP)D-R87, an albumin-binding moiety, and a chelating moiety; wherein D is 0 or 1;SPis a spacer;each R87is independently selected from the group consisting of organic molecules, inorganic molecules, organometallic molecules, resins, beads, glass,microparticles, nanoparticles, gels, surfaces, and cells;and at least one of moieties Q1and Q2is not hydrogen.

8. The combination according to claim 7, wherein Q1and Q2are selected from the group of hydrogen, Ci-C8alkyl, phenyl, 2-pyridyl, 3-pyridyl, 4-pyridyl, 2,6- pyrimidyl, 2,5-pyrimidyl, 3,5-pyrimidyl, and 2,4-pyrimidyl; and Q1and Q2not being hydrogen are optionally substituted as defined in claim 7.

9. The combination according to any one of claims 7 to 8, wherein in Formula(4):(a) Q1and Q2are selected from the group consisting of 2-pyridyl, 3-pyridyl, and 4- pyridyl;(b) Q1is selected from the group consisting of 2,6-pyrimidyl, 2,5-pyrimidyl, 3,5- pyrmidyl, and 2,4-pyrimidyl; and Q2is (hetero)alkyl; or(c) Q1is phenyl and Q2is hydrogen;and in (a)-(c) all Q1and Q2not being hydrogen are optionahy substituted as defined in claim 7.

10. The compound according to any one of claims 1 to 5, or the combination according to any one of claims 6 to 9 for use as a medicament.

11. The compound according to any one of claims 1 to 5, or the combination according to any one of claims 6 to 9, for use in the treatment of a disease, preferably cancer, in a subject, preferably a human, wherein the treatment is radiotherapy.

12. The compound according to any one of claims 1 to 5, or the combination according to any one of claims 6 to 9, for use in a diagnostic method comprising the steps of(a) administering a compound according to Formula (1) as defined in any one of claims 1 to 5, to a subject, preferably a human;(b) administering a Cleaving Agent as defined in any one of claims 6 to 9, to said subject;(c) imaging the compound according to Formula (1) present in the subject to collect data;(d) comparing said data to standard values;(e) finding a significant deviation from said standard values during comparison;(f) attributing the significant deviation to a particular clinical picture, preferably to cancer.

13. A non-therapeutic method for imaging a compound according to any one of claims 1 to 5 in a subject, preferably a human, said non-therapeutic method comprising the steps of(a) administering a compound according to Formula (1) as defined in any one of claims 1 to 5, to the subject;(b) administering a Cleaving Agent as defined in any one of claims 6 to 9, to said subject;(c) imaging the compound according to Formula (1) present in the subject.

14. Non-therapeutic use of a compound according to any one of claims 1 to 5, or a combination according to any one of claims 6 to 9, for imaging in a subject, preferably a human.Statement under Article 19(1) PCTIn the Written Opinion, the only issues raised concern clarity. The presentamendments overcome all these issues.In claim 1, the Label and Administration Agent are now defined in all instances, because they are defined in the beginning of the claim. In particular, we note that the Label and Administration Agent are now defined for all occurrences in Formulae (2) and (3). This overcomes the objections raised under Items VIII.1 and VIII.2 of the Written Opinion.In claim 1, the parameter i in relation to R47 is now properly defined, not only with reference to the preferred definition. This obviates the observation under Item VIII.3 of the Written Opinion.In claim 7, R87is now defined. In addition, Spis already defined as a spacer in claim 1 on which claim 7 depends. To expedite prosecution, SP is now more explicitly defined in claim 7. Finally, we note that D was already defined in original claim 7 (page 205, line 1 of the application as filed). Consequently, the group -(SP)D-R87in claim 7 is clearly defined. The issue raised under Item VIII.4 is thus overcome.In short, the amended claims fully comply with the requirements of the PCT.

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