A conjugate of formula I: L-(DL)P  (1)wherein L is a Ligand unit, DL is a Drug Linker unit of formula II:wherein either:(a) R10 and R11 form a nitrogen-carbon double bond between the nitrogen and carbon atoms to which they are bound; or(b) R11 is OH, and R10 is:p is an integer of from 1 to 20.

Incorporated by reference in its entirety herein is a computer-readable nucleotide/amino acid sequence listing submitted herewith and identified as follows: One 45,384 Byte ASCII (Text) file named “36676_251_ST25.TXT,” created on Oct. 13, 2022. The present invention relates to conjugates comprising a specific pyrrolobenzodiazepine (PBD), and the precursor drug linker used to make such conjugates.

BACKGROUND TO THE INVENTION

They differ in the number, type and position of substituents, in both their aromatic A rings and pyrrolo C rings, and in the degree of saturation of the C ring. In the B-ring there is either an imine (N═C), a carbinolamine (NH—CH(OH)), or a carbinolamine methyl ether (NH—CH(OMe)) at the N10-C11 position which is the electrophilic centre responsible for alkylating DNA. All of the known natural products have an (S)-configuration at the chiral C11a position which provides them with a right-handed twist when viewed from the C ring towards the A ring. This gives them the appropriate three-dimensional shape for isohelicity with the minor groove of B-form DNA, leading to a snug fit at the binding site (Kohn, InAntibiotics III. Springer-Verlag, New York, pp. 3-11 (1975); Hurley and Needham-VanDevanter,Acc. Chem. Res.,19, 230-237 (1986)). Their ability to form an adduct in the minor groove, enables them to interfere with DNA processing, hence their use as antitumour agents.

It has been previously disclosed that the biological activity of this molecules can be potentiated by joining two PBD units together through their C8/C′-hydroxyl functionalities via a flexible alkylene linker (Bose, D. S., et al.,J. Am. Chem. Soc.,114, 4939-4941 (1992); Thurston, D. E., et al.,J. Org. Chem.,61, 8141-8147 (1996)). The PBD dimers are thought to form sequence-selective DNA lesions such as the palindromic 5′-Pu-GATC-Py-3′ interstrand cross-link (Smellie, M., et al.,Biochemistry,42, 8232-8239 (2003); Martin, C., et al.,Biochemistry,44, 4135-4147) which is thought to be mainly responsible for their biological activity.

One example of a PBD dimer is SG2000 (SJG-136):

Dimeric PBD compounds bearing C2 aryl substituents, such as SG2202 (ZC-207), are disclosed in WO 2005/085251:

and in WO2006/111759, bisulphites of such PBD compounds, for example SG2285 (ZC-423):

These compounds have been shown to be highly useful cytotoxic agents (Howard, P. W., et al.,Bioorg. Med. Chem. (2009), doi: 10.1016/j.bmcl.2009.09.012).

In an impact study submitted to the 2014 Research Excellence Framework (REF) in the United Kingdom by University College London (available at impact.ref.ac.uk/casestudies2/refservice.svc/GetCaseStudyPDF/35393), it was commented that:

“The next generation of PBD dimers, which are more potent than SG2000, have been developed, including SG2057 and SG2202. They exhibit picomolar/sub-picomolar activity against a range of human tumour cell lines and demonstrate curative activity in human tumour xenograft models.” making reference to: Hartley J A, et al.,DNA interstrand cross-linking and in vivo antitumor activity of the extended pyrrolo[2,1-c][1,4]benzodiazepine dimer SG2057. Invest New Drugs. 2012 June; 30(3):950-8.dx.doi.org/10.1007/s10637-011-9647-z (herein after “Hartley et al (2012)”) and:

“The ability to generate such cytotoxic molecules that display exquisite potency suggested a potential role in strategies aimed at targeting and releasing highly cytotoxic agents directly at a tumour site. An example is as the ‘warhead’ component of an antibody drug conjugate (ADC). The fully synthetic PBD dimers are ideally suited for the role of warhead in an ADC approach.”

The Hartley et al (2012) paper comments in its summary that “SG2057 is therefore a highly active antiumour agent, with more potent in vitro activity and superior in vivo activity to SG2000, warranting further development”.

SG2057 has the structure:

Antibody drug conjugates using SG2057 as a warhead were first disclosed in WO 2011/130598. For example, claim 54 of this application includes the formula:

wherein n is from 1 to 24, more preferably 4 to 8. The following drug linkers were exemplified: n=4, 15c; n=8, 15 d; n=24, 15e.

Claim 54 of this application also includes the formula:

wherein n is from 1 to 24, more preferably 4 to 8. The following drug linkers were exemplified: n=8, 58; n=24, 61.

WO 2013/055987 discloses the drug linkers 14 and 22:

and their use in antibody-drug conjugates.

More recently, the warhead:

has been used in drug linkers and antibody-drug conjugates. WO 2014/057074 discloses:

DISCLOSURE OF THE INVENTION

The present inventors have surprisingly found that although SG2000 is at least 10 times less cytotoxic than SG2057 (see Hartley et al 2012), particular antibody-drug conjugates appear to show at least comparable activity. These conjugates have been shown to have surprisingly well tolerated in toxicity studies in a variety of species. This leads to the conjugates exhibiting high therapeutic indices and thus are promising clinical candidates.

In a first aspect, the present invention provides Conjugates of formula I:
L-(DL)P  (I)

wherein L is a Ligand unit (i.e., a targeting agent), DLis a Drug Linker unit of formula II:

wherein

(a) R10and R11form a nitrogen-carbon double bond between the nitrogen and carbon atoms to which they are bound; or

p is an integer of from 1 to 20.

The Ligand unit, described more fully below, is a targeting agent that binds to a target moiety. The Ligand unit can, for example, specifically bind to a cell component (a Cell Binding Agent) or to other target molecules of interest. The Ligand unit can be, for example, a protein, polypeptide or peptide, such as an antibody, an antigen-binding fragment of an antibody, or other binding agent, such as an Fc fusion protein.

A second aspect of the present invention provides a compound of formula III:

wherein

(a) R10and R11form a nitrogen-carbon double bond between the nitrogen and carbon atoms to which they are bound; or

A third aspect of the present invention provides the use of a conjugate of the first aspect of the invention in the manufacture of a medicament for treating a proliferative disease. The third aspect also provides a conjugate of the first aspect of the invention for use in the treatment of a proliferative disease. The third aspect also provides a method of treating a proliferative disease comprising administering a therapeutically effective amount of a conjugate of the first aspect of the invention to a patient in need thereof.

One of ordinary skill in the art is readily able to determine whether or not a candidate conjugate treats a proliferative condition for any particular cell type. For example, assays which may conveniently be used to assess the activity offered by a particular compound are described in the examples below.

A fourth aspect of the present invention provides the synthesis of a conjugate of the first aspect of the invention comprising conjugating a compound (drug linker) of the second aspect of the invention with a Ligand Unit.

In the first aspect DLis selected from DL-A and DL-B:

In the second aspect, the compound is selected from A and B:

Ligand Unit

The Ligand Unit may be of any kind, and include a protein, polypeptide, peptide and a non-peptidic agent that specifically binds to a target molecule. In some embodiments, the Ligand unit may be a protein, polypeptide or peptide. In some embodiments, the Ligand unit may be a cyclic polypeptide. These Ligand units can include antibodies or a fragment of an antibody that contains at least one target molecule-binding site, lymphokines, hormones, growth factors, or any other cell binding molecule or substance that can specifically bind to a target.

The terms “specifically binds” and “specific binding” refer to the binding of an antibody or other protein, polypeptide or peptide to a predetermined molecule (e.g., an antigen). Typically, the antibody or other molecule binds with an affinity of at least about 1×107 MA, and binds to the predetermined molecule with an affinity that is at least two-fold greater than its affinity for binding to a non-specific molecule (e.g., BSA, casein) other than the predetermined molecule or a closely-related molecule.

Examples of Ligand units include those agents described for use in WO 2007/085930, which is incorporated herein.

In some embodiments, the Ligand unit is a Cell Binding Agent that binds to an extracellular target on a cell. Such a Cell Binding Agent can be a protein, polypeptide, peptide or a non-peptidic agent. In some embodiments, the Cell Binding Agent may be a protein, polypeptide or peptide. In some embodiments, the Cell Binding Agent may be a cyclic polypeptide. The Cell Binding Agent also may be antibody or an antigen-binding fragment of an antibody. Thus, in one embodiment, the present invention provides an antibody-drug conjugate (ADC).

Cell Binding Agent

A cell binding agent may be of any kind, and include peptides and non-peptides. These can include antibodies or a fragment of an antibody that contains at least one binding site, lymphokines, hormones, hormone mimetics, vitamins, growth factors, nutrient-transport molecules, or any other cell binding molecule or substance.

Peptides

In one embodiment, the cell binding agent is a linear or cyclic peptide comprising 4-30, preferably 6-20, contiguous amino acid residues. In this embodiment, it is preferred that one cell binding agent is linked to one monomer or dimer pyrrolobenzodiazepine compound.

In one embodiment the cell binding agent comprises a peptide that binds integrin αvβ6. The peptide may be selective for αVβ6over XYS.

In one embodiment the cell binding agent comprises the A20FMDV-Cys polypeptide. The A20FMDV-Cys has the sequence: NAVPNLRGDLQVLAQKVARTC. Alternatively, a variant of the A20FMDV-Cys sequence may be used wherein one, two, three, four, five, six, seven, eight, nine or ten amino acid residues are substituted with another amino acid residue. Furthermore, the polypeptide may have the sequence NAVXXXXXXXXXXXXXXXRTC.

Antibodies

The term “antibody” herein is used in the broadest sense and specifically covers monoclonal antibodies, polyclonal antibodies, dimers, multimers, multispecific antibodies (e.g., bispecific antibodies), and antibody fragments, so long as they exhibit the desired biological activity (Miller et al (2003) Jour. of Immunology 170:4854-4861). Antibodies may be murine, human, humanized, chimeric, or derived from other species. An antibody is a protein generated by the immune system that is capable of recognizing and binding to a specific antigen. (Janeway, C., Travers, P., Walport, M., Shlomchik (2001)Immuno Biology,5th Ed., Garland Publishing, New York). A target antigen generally has numerous binding sites, also called epitopes, recognized by CDRs on multiple antibodies. Each antibody that specifically binds to a different epitope has a different structure. Thus, one antigen may have more than one corresponding antibody. An antibody includes a full-length immunoglobulin molecule or an immunologically active portion of a full-length immunoglobulin molecule, i.e., a molecule that contains an antigen binding site that immunospecifically binds an antigen of a target of interest or part thereof, such targets including but not limited to, cancer cell or cells that produce autoimmune antibodies associated with an autoimmune disease. The immunoglobulin can be of any type (e.g. IgG, IgE, IgM, IgD, and IgA), class (e.g. IgG1, IgG2, IgG3, IgG4, IgA1 and IgA2) or subclass of immunoglobulin molecule. The immunoglobulins can be derived from any species, including human, murine, or rabbit origin.

“Antibody fragments” comprise a portion of a full length antibody, generally the antigen binding or variable region thereof. Examples of antibody fragments include Fab, Fab′, F(ab′)2, and scFv fragments; diabodies; linear antibodies; fragments produced by a Fab expression library, anti-idiotypic (anti-Id) antibodies, CDR (complementary determining region), and epitope-binding fragments of any of the above which immunospecifically bind to cancer cell antigens, viral antigens or microbial antigens, single-chain antibody molecules; and multispecific antibodies formed from antibody fragments.

An “intact antibody” herein is one comprising a VL and VH domains, as well as a light chain constant domain (CL) and heavy chain constant domains, CH1, CH2 and CH3. The constant domains may be native sequence constant domains (e.g. human native sequence constant domains) or amino acid sequence variant thereof. The intact antibody may have one or more “effector functions” which refer to those biological activities attributable to the Fc region (a native sequence Fc region or amino acid sequence variant Fc region) of an antibody. Examples of antibody effector functions include C1q binding; complement dependent cytotoxicity; Fc receptor binding; antibody-dependent cell-mediated cytotoxicity (ADCC); phagocytosis; and down regulation of cell surface receptors such as B cell receptor and BCR.

Techniques to reduce the in vivo immunogenicity of a non-human antibody or antibody fragment include those termed “humanisation”.

A “humanized antibody” refers to a polypeptide comprising at least a portion of a modified variable region of a human antibody wherein a portion of the variable region, preferably a portion substantially less than the intact human variable domain, has been substituted by the corresponding sequence from a non-human species and wherein the modified variable region is linked to at least another part of another protein, preferably the constant region of a human antibody. The expression “humanized antibodies” includes human antibodies in which one or more complementarity determining region (“CDR”) amino acid residues and/or one or more framework region (“FW” or “FR”) amino acid residues are substituted by amino acid residues from analogous sites in rodent or other non-human antibodies. The expression “humanized antibody” also includes an immunoglobulin amino acid sequence variant or fragment thereof that comprises an FR having substantially the amino acid sequence of a human immunoglobulin and a CDR having substantially the amino acid sequence of a non-human immunoglobulin.

“Humanized” forms of non-human (e.g., murine) antibodies are chimeric antibodies that contain minimal sequence derived from non-human immunoglobulin. Or, looked at another way, a humanized antibody is a human antibody that also contains selected sequences from non-human (e.g. murine) antibodies in place of the human sequences. A humanized antibody can include conservative amino acid substitutions or non-natural residues from the same or different species that do not significantly alter its binding and/or biologic activity. Such antibodies are chimeric antibodies that contain minimal sequence derived from non-human immunoglobulins.

CDR Grafting

In this technique, the humanized antibodies are human immunoglobulins (recipient antibody) in which residues from a complementary-determining region (CDR) of the recipient antibody are replaced by residues from a CDR of a non-human species (donor antibody) such as mouse, rat, camel, bovine, goat, or rabbit having the desired properties (in effect, the non-human CDRs are ‘grafted’ onto the human framework). In some instances, framework region (FR) residues of the human immunoglobulin are replaced by corresponding non-human residues (this may happen when, for example, a particular FR residue has significant effect on antigen binding).

Furthermore, humanized antibodies can comprise residues that are found neither in the recipient antibody nor in the imported CDR or framework sequences. These modifications are made to further refine and maximize antibody performance. Thus, in general, a humanized antibody will comprise all of at least one, and in one aspect two, variable domains, in which all or all of the hypervariable loops correspond to those of a non-human immunoglobulin and all or substantially all of the FR regions are those of a human immunoglobulin sequence. The humanized antibody optionally also will comprise at least a portion of an immunoglobulin constant region (Fc), or that of a human immunoglobulin.

Guided Selection

The method consists of combining the VHor VLdomain of a given non-human antibody specific for a particular epitope with a human VHor VLlibrary and specific human V domains are selected against the antigen of interest. This selected human VH is then combined with a VL library to generate a completely human VH×VL combination. The method is described in Nature Biotechnology (N.Y.) 12, (1994) 899-903.

Composite Antibodies

In this method, two or more segments of amino acid sequence from a human antibody are combined within the final antibody molecule. They are constructed by combining multiple human VH and VL sequence segments in combinations which limit or avoid human T cell epitopes in the final composite antibody V regions. Where required, T cell epitopes are limited or avoided by, exchanging V region segments contributing to or encoding a T cell epitope with alternative segments which avoid T cell epitopes. This method is described in US 2008/0206239 A1.

This method involves the removal of human (or other second species) T-cell epitopes from the V regions of the therapeutic antibody (or other molecule). The therapeutic antibodies V-region sequence is analysed for the presence of MHC class II-binding motifs by, for example, comparison with databases of MHC-binding motifs (such as the “motifs” database hosted at www.wehi.edu.au). Alternatively, MHC class II-binding motifs may be identified using computational threading methods such as those devised by Altuvia et al. (J. Mol. Biol. 249 244-250 (1995)); in these methods, consecutive overlapping peptides from the V-region sequences are testing for their binding energies to MHC class II proteins. This data can then be combined with information on other sequence features which relate to successfully presented peptides, such as amphipathicity, Rothbard motifs, and cleavage sites for cathepsin B and other processing enzymes.

Once potential second species (e.g. human) T-cell epitopes have been identified, they are eliminated by the alteration of one or more amino acids. The modified amino acids are usually within the T-cell epitope itself, but may also be adjacent to the epitope in terms of the primary or secondary structure of the protein (and therefore, may not be adjacent in the primary structure). Most typically, the alteration is by way of substitution but, in some circumstances amino acid addition or deletion will be more appropriate.

All alterations can be accomplished by recombinant DNA technology, so that the final molecule may be prepared by expression from a recombinant host using well established methods such as Site Directed Mutagenesis. However, the use of protein chemistry or any other means of molecular alteration is also possible.

Resurfacing

This method involves:(a) determining the conformational structure of the variable region of the non-human (e.g. rodent) antibody (or fragment thereof) by constructing a three-dimensional model of the non-human antibody variable region;(b) generating sequence alignments using relative accessibility distributions from x-ray crystallographic structures of a sufficient number of non-human and human antibody variable region heavy and light chains to give a set of heavy and light chain framework positions wherein the alignment positions are identical in 98% of the sufficient number of non-human antibody heavy and light chains;(c) defining for the non-human antibody to be humanized, a set of heavy and light chain surface exposed amino acid residues using the set of framework positions generated in step (b);(d) identifying from human antibody amino acid sequences a set of heavy and light chain surface exposed amino acid residues that is most closely identical to the set of surface exposed amino acid residues defined in step (c), wherein the heavy and light chain from the human antibody are or are not naturally paired;(e) substituting, in the amino acid sequence of the non-human antibody to be humanized, the set of heavy and light chain surface exposed amino acid residues defined in step (c) with the set of heavy and light chain surface exposed amino acid residues identified in step (d);(f) constructing a three-dimensional model of the variable region of the non-human antibody resulting from the substituting specified in step (e);(g) identifying, by comparing the three-dimensional models constructed in steps (a) and (f), any amino acid residues from the sets identified in steps (c) or (d), that are within 5 Angstroms of any atom of any residue of the complementarity determining regions of the non-human antibody to be humanized; and(h) changing any residues identified in step (g) from the human to the original non-human amino acid residue to thereby define a non-human antibody humanizing set of surface exposed amino acid residues; with the proviso that step (a) need not be conducted first, but must be conducted prior to step (g).

The method compares the non-human sequence with the functional human germline gene repertoire. Those human genes encoding canonical structures identical or closely related to the non-human sequences are selected. Those selected human genes with highest homology within the CDRs are chosen as FR donors. Finally, the non-human CDRs are grafted onto these human FRs. This method is described in patent WO 2005/079479 A2.

Human String Content Optimization

This method compares the non-human (e.g. mouse) sequence with the repertoire of human germline genes and the differences are scored as Human String Content (HSC) that quantifies a sequence at the level of potential MHC/T-cell epitopes. The target sequence is then humanized by maximizing its HSC rather than using a global identity measure to generate multiple diverse humanized variants (described in Molecular Immunology, 44, (2007) 1986-1998).

Framework Shuffling

The CDRs of the non-human antibody are fused in-frame to cDNA pools encompassing all known heavy and light chain human germline gene frameworks. Humanised antibodies are then selected by e.g. panning of the phage displayed antibody library. This is described in Methods 36, 43-60 (2005).

Examples of cell binding agents include those agents described for use in WO 2007/085930, which is incorporated herein.

Tumour-associate antigens and cognate antibodies for use in embodiments of the present invention are listed below.

Tumor-Associated Antigens and Cognate Antibodies

Nucleotide

Polypeptide

Nucleotide

Polypeptide

CROSS REFERENCES

Nucleotide

Polypeptide

CROSS REFERENCES

Nucleotide

Polypeptide

CROSS REFERENCES

Nucleotide

Polypeptide

CROSS REFERENCES

Nucleotide

Polypeptide

CROSS REFERENCES

Nucleotide

Polypeptide

CROSS REFERENCES

Nucleotide

Polypeptide

CROSS REFERENCES

Nucleotide

Polypeptide

CROSS REFERENCES

CROSS REFERENCES

Nucleotide

Polypeptide

CROSS REFERENCES

Nucleotide

Polypeptide

CROSS REFERENCES

Nucleotide

Polypeptide

CROSS REFERENCES

Nucleotide

Genbank accession no M26004

Polypeptide

CROSS REFERENCES

Nucleotide

Genbank accession no NM_000626

Polypeptide

CROSS REFERENCES

Nucleotide

Genbank accession no NM_030764

Polypeptide

CROSS REFERENCES

Nucleotide

Genbank accession no M11730

Polypeptide

CROSS REFERENCES

Antibodies

Abbott: US20110177095For example, an antibody comprising CDRs having overall at least 80% sequence identity to CDRs having amino acid sequences of SEQ ID NO:3 (CDR-H1), SEQ ID NO:4 (CDR-H2), SEQ ID NO:5 (CDR-H3), SEQ ID NO:104 and/or SEQ ID NO:6 (CDR-L1), SEQ ID NO:7 (CDR-L2), and SEQ ID NO:8 (CDR-L3), wherein the anti-HER2 antibody or anti-HER2 binding fragment has reduced immunogenicity as compared to an antibody having a VH of SEQ ID NO:1 and a VL of SEQ ID NO:2.

Pertuzumab (Genentech)US20110117097for example, see SEQ IDs No. 15&16, SEQ IDs No. 17&18, SEQ IDs No. 23&24 & ATCC accession numbers HB-12215, HB-12216, CRL 10463, HB-12697.US20090285837US20090202546for example, ATCC accession numbers: HB-12215, HB-12216, CRL 10463, HB-12698.US20060088523for example, ATCC accession numbers: HB-12215, HB-12216for example, an antibody comprising the variable light and variable heavy amino acid sequences in SEQ ID Nos. 3 and 4, respectively.for example, an antibody comprising a light chain amino acid sequence selected from SEQ ID No. 15 and 23, and a heavy chain amino acid sequence selected from SEQ ID No. 16 and 24US20060018899for example, ATCC accession numbers: (7C2) HB-12215, (7F3) HB-12216, (4D5) CRL-10463, (2C4) HB-12697.for example, an antibody comprising the amino acid sequence in SEQ ID No. 23, or a deamidated and/or oxidized variant thereof.US2011/0159014for example, an antibody having a light chain variable domain comprising the hypervariable regions of SEQ ID NO: 1”.For example, an antibody having a heavy chain variable domain comprising the hypervariable regions of SEQ ID NO: 2.US20090187007

Nucleotide

Genbank accession no M18728

Polypeptide

CROSS REFERENCES

Nucleotide

Genbank accession no BC017023

Polypeptide

CROSS REFERENCES

Nucleotide

Genbank accession no AF184971

Polypeptide

CROSS REFERENCES

Nucleotide

Genbank accession no AF229053

Polypeptide

CROSS REFERENCES

Nucleotide

Genbank accession no NM_004442

Polypeptide

CROSS REFERENCES

Nucleotide

CROSS REFERENCES

Nucleotide

Genbank accession no AJ297436

Polypeptide

CROSS REFERENCES

Nucleotide

Genbank accession no AY260763

Polypeptide

CROSS REFERENCES

Nucleotide

Genbank accession no AF116456

Polypeptide

CROSS REFERENCES

Nucleotide

Genbank accession no AK026467

Polypeptide

CROSS REFERENCES

Nucleotide

Genbank accession no X52785

Polypeptide

CROSS REFERENCES

Other Information

Antibodies

(28) CD79a (CD79A, CD79alpha), Immunoglobulin-Associated Alpha, a B Cell-Specific Protein that Covalently Interacts with Ig Beta (CD79B) and Forms a Complex on the Surface with Ig M 35 Molecules, Transduces a Signal Involved in B-Cell Differentiation), pl: 4.84, MW: 25028 TM: 2

Nucleotide

Genbank accession no NM_001783

Polypeptide

CROSS REFERENCES

Nucleotide

Genbank accession no NM_001716

Polypeptide

CROSS REFERENCES

Nucleotide

Genbank accession no NM_002120

Polypeptide

CROSS REFERENCES

Nucleotide

Genbank accession no NM_002561

Polypeptide

CROSS REFERENCES

Nucleotide

Genbank accession no NM_001782

Polypeptide

CROSS REFERENCES

(33) LY64 (Lymphocyte Antigen 64 (RP105), Type I Membrane Protein of the Leucine Rich Repeat (LRR) Family, Regulates B-Cell Activation and Apoptosis, Loss of Function is Associated with Increased Disease Activity in Patients with Systemic Lupus Erythematosis); 661 aa, pl: 6.20, MW: 74147 TM: 1 [P] Gene Chromosome: 5q12).

Nucleotide

Genbank accession no NM_005582

Polypeptide

CROSS REFERENCES

Nucleotide

Genbank accession no NM_052938

Polypeptide

CROSS REFERENCES

(35) IRTA2 (Immunoglobulin Superfamily Receptor Translocation Associated 2, a Putative Immunoreceptor with Possible Roles in B Cell Development and Lymphomagenesis; Deregulation of the Gene by Translocation Occurs in Some B Cell Malignancies); 977 aa, pl: 6.88, MW: 106468, TM: 1 [P] Gene Chromosome: 1q21)

Nucleotide

Genbank accession no AF343662

Polypeptide

CROSS REFERENCES

Nucleotide

Genbank accession no AF179274

Polypeptide

CROSS REFERENCES

Nucleotide

Genbank accession no M99487

Polypeptide

CROSS REFERENCES

Other Information

Antibodies

Other human anti-PSMA antibodies include the antibodies disclosed in PCT Publication WO 03/034903 and US Application No. 2004/0033229.

PSMA Development Company/Progenics/Cytogen—Seattle Genetics: mAb 3.9, produced by the hybridoma deposited under ATCC Accession No. PTA-3258 or mAb 10.3, produced by the hybridoma deposited under ATCC Accession No. PTA-3347—U.S. Pat. No. 7,850,971

Nucleotide

Genbank accession no NM_001050

Polypeptide

CROSS REFERENCES

Other Information

Nucleotide

Genbank accession no D16827

Polypeptide

CROSS REFERENCES

Other Information

Nucleotide

Polypeptide

CROSS REFERENCES

Other Information

Nucleotide

Genbank accession no NM_000888

Polypeptide

CROSS REFERENCES

Other Information

Antibodies

Centocor (J&J): U.S. Pat. Nos. 7,550,142; 7,163,681For example in U.S. Pat. No. 7,550,142— an antibody having human heavy chain and human light chain variable regions comprising the amino acid sequences shown in SEQ ID NO: 7 and SEQ ID NO: 8.

Nucleotide

Genbank accession no M17303

Polypeptide

CROSS REFERENCES

Other Information

Antibodies

BioAlliance: U.S. Pat. Nos. 7,982,017; 7,674,605U.S. Pat. No. 7,674,605an antibody comprising the heavy chain variable region sequence from the amino acid sequence of SEQ ID NO: 1, and the light chain variable region sequence from the amino acid sequence of SEQ ID NO:2.an antibody comprising the heavy chain variable region sequence from the amino acid sequence of SEQ ID NO:5, and the light chain variable region sequence from the amino acid sequence of SEQ ID NO:6.

Nucleotide

Genbank accession no M35073

Polypeptide

CROSS REFERENCES

Other Information

Official Symbol: MET

Antibodies

Abgenix/Pfizer: US20100040629for example, the antibody produced by hybridoma 13.3.2 having American Type Culture Collection (ATCC) accession number PTA-5026; the antibody produced by hybridoma 9.1.2 having ATCC accession number PTA-5027; the antibody produced by hybridoma 8.70.2 having ATCC accession number PTA-5028; or the antibody produced by hybridoma 6.90.3 having ATCC accession number PTA-5029.

Amgen/Pfizer: US20050054019for example, an antibody comprising a heavy chain having the amino acid sequences set forth in SEQ ID NO: 2 where X2 is glutamate and X4 is serine and a light chain having the amino acid sequence set forth in SEQ ID NO: 4 where X8 is alanine, without the signal sequences; an antibody comprising a heavy chain having the amino acid sequences set forth in SEQ ID NO: 6 and a light chain having the amino acid sequence set forth in SEQ ID NO: 8, without the signal sequences; an antibody comprising a heavy chain having the amino acid sequences set forth in SEQ ID NO: 10 and a light chain having the amino acid sequence set forth in SEQ ID NO: 12, without the signal sequences; or an antibody comprising a heavy chain having the amino acid sequences set forth in SEQ ID NO: 14 and a light chain having the amino acid sequence set forth in SEQ ID NO: 16, without the signal sequences.

Novartis: US20090175860for example, an antibody comprising the sequences of CDR1, CDR2 and CDR3 of heavy chain 4687, wherein the sequences of CDR1, CDR2, and CDR3 of heavy chain 4687 are residues 26-35, 50-65, and 98-102, respectively, of SEQ ID NO: 58; and the sequences of CDR1, CDR2, and CDR3 of light chain 5097, wherein the sequences of CDR1, CDR2, and CDR3 oflight chain 5097 are residues 24-39,55-61, and 94-100 of SEQ ID NO: 37.

Sumsung: US 20110129481—for example a monoclonal antibody produced from a hybridoma cell having accession number KCLRF-BP-00219 or accession number of KCLRF-BP-00223.

Samsung: US 20110104176—for example an antibody produced by a hybridoma cell having Accession Number: KCLRF-BP-00220.

Nucleotide

Genbank accession no J05581

Polypeptide

CROSS REFERENCES

Other Information

Antibodies

Nucleotide

Polypeptide

CROSS REFERENCES

Other Information

Antibodies

Institute of Virology, Slovak Academy of Sciences: U.S. Pat. No. 7,816,493for example the M75 monoclonal antibody that is secreted from the hybridoma VU-M75, which was deposited at the American Type Culture Collection under ATCC No. HB 11128; or the V/10 monoclonal antibody secreted from the hybridoma V/10-VU, which was deposited at the International Depository Authority of the Belgian Coordinated Collection of Microorganisms (BCCM) at the Laboratorium voor Moleculaire Bioloqie-Plasmidencollectie (LMBP) at the Universeit Gent in Gent, Belgium, under Accession No. LMBP 6009CB.

Institute of Virology, Slovak Academy of Sciences US20080177046; US20080176310; US20080176258; US20050031623

Wilex: U.S. Pat. No. 7,691,375—for example the antibody produced by the hybridoma cell line DSM ASC 2526.

Nucleotide

Polypeptide

U.S. Pat. Nos. 7,628,986 and 7,736,644 (Amgen)For example, a heavy chain variable region amino acid sequence selected from the group consisting of SEQ ID NO: 142 and variants & a light chain variable region amino acid sequence selected from the group consisting of: SEQ ID NO: 144 and variants.

US20090240038 (Amgen)For example, an antibody having at least one of the heavy or light chain polypeptides comprises an amino acid sequence that is at least 90% identical to the amino acid sequence selected from the group consisting of: SEQ ID NO: 2, SEQ ID NO: 19, SEQ ID NO: 142, SEQ ID NO: 144, and any combination thereof.

US20090156790 (Amgen)For example, antibody having heavy chain polypeptide and a light chain polypeptide, wherein at least one of the heavy or light chain polypeptides comprises an amino acid sequence that is at least 90% identical to the amino acid sequence selected from the group consisting of: SEQ ID NO: 2, SEQ ID NO: 19, SEQ ID NO: 142, SEQ ID NO: 144, and any combination thereof.

MR1-1 (U.S. Pat. No. 7,129,332; Duke)For example, a variant antibody having the sequence of SEQ ID NO.18 with the substitutions S98P-T99Y in the CDR3 VH, and F92W in CDR3 VL.

US20090311803 (Harvard University)For example, SEQ ID NO:9 for antibody heavy chain variable region, and SEQ ID NO: 3 for light chain variable region amino acid sequences

US20070274991 (EMD72000, also known as matuzumab; Harvard University)For example, SEQ ID NOs: 3 & 9 for light chain and heavy chain respectively

Nucleotide

Polypeptide

Other Information

Antibodies

U.S. Pat. No. 7,557,189 (Immunogen)For example, an antibody or fragment thereof comprising a heavy chain variable region which comprises three CDRs having the amino acid sequences of SEQ ID NOs:1-3 and a light chain variable region comprising three CDRs having the amino acid sequences of SEQ ID NOs:4-6.

Nucleotide

Polypeptide

Other Information

Antibodies

U.S. Pat. No. 7,109,304 (Immunomedics)For example, an antibody comprising the sequence of hA19Vk (SEQ ID NO:7) and the sequence of hA19VH (SEQ ID NO:10)

U.S. Pat. No. 7,902,338 (Immunomedics)For example, an antibody or antigen-binding fragment thereof that comprises the light chain complementarity determining region CDR sequences CDR1 of SEQ ID NO: 16 (KASQSVDYDGDSYLN); CDR2 of SEQ ID NO: 17 (DASNLVS); and CDR3 of SEQ ID NO: 18 (QQSTEDPWT) and the heavy chain CDR sequences CDR1 of SEQ ID NO: 19 (SYWMN); CDR2 of SEQ ID NO: 20 (QIWPGDGDTNYNGKFKG) and CDR3 of SEQ ID NO: 21 (RETTTVGRYYYAMDY) and also comprises human antibody framework (FR) and constant region sequences with one or more framework region amino acid residues substituted from the corresponding framework region sequences of the parent murine antibody, and wherein said substituted FR residues comprise the substitution of serine for phenylalanine at Kabat residue 91 of the heavy chain variable region.

U.S. Pat. No. 7,968,687 (Seattle Genetics)An antibody or antigen-binding fragment comprising a heavy chain variable domain comprising the amino acid sequence of SEQ ID NO:9 and a light chain variable domain comprising the amino acid sequence of SEQ ID NO: 24.

Nucleotide

Polypeptide

Other Information

Antibodies

U.S. Pat. No. 6,521,230 (Novartis/UCL: Baxilisimab [Simulect])For example, an antibody having an antigen binding site comprises at least one domain which comprises CDR1 having the amino acid sequence in SEQ. ID. NO: 7, CDR2 having the amino acid sequence in SEQ. ID. NO: 8, and CDR3 chaving the amino acid sequence in SEQ. ID. NO: 9; or said CDR1, CDR2 and CDR3 taken in sequence as a whole comprise an amino acid sequence which is at least 90% identical to SEQ. ID. NOs: 7, 8 and 9 taken in sequence as a whole.

Nucleotide

Polypeptide

Other Information

Antibodies

Nucleotide

Other Information

Nucleotide

Polypeptide

Other Information

Nucleotide

Polypeptide

Other Information

Nucleotide

Polypeptide

Other Information

Other Designations: C-type lectin domain family 14 member A; CIECT and EGF-like domain containing protein; epidermal growth factor receptor 5

Nucleotide

Polypeptide

Other Information

Nucleotide

Polypeptide

Other Information

Antibodies

Antibodies

Nucleotide

Polypeptide

Other Information

Nucleotide

Polypeptide

Other Information

Nucleotide

Polypeptide

Other Information

Nucleotide

Polypeptide

Other Information

Nucleotide

Polypeptide

Nucleotide

Polypeptide

Other Information

Other Designations: antigen recognized by monoclonal antibody 5.1H11; neural cell adhesion molecule, NCAM

Antibodies

Antibodies

Nucleotide

Polypeptide

Other Information

Antibodies

Nucleotide

Polypeptide

Other Information

Antibodies

Nucleotide

Polypeptide

Other Information

Other Designations: T cell immunoglobin domain and mucin domain protein 1; T-cell membrane protein 1; kidney injury molecule 1

Nucleotide

Other Information

Nucleotide

Polypeptide

Other Information

Nucleotide

Polypeptide

Other Information

Antibodies

Nucleotide

Polypeptide

Other Information

Antibodies

Nucleotide

Polypeptide

Other Information

Antibodies

In humans, 24 members of the family have been described—see literature reference.

Nucleotide

Polypeptide

Other Information

Antibodies

Nucleotide

Polypeptide

Other Information

Antibodies

Nucleotide

Polypeptide

Other Information

Nucleotide

Polypeptide

Other Information

Antibodies

Nucleotide

Polypeptide

Other Information

Antibodies

Nucleotide

Polypeptide

Other Information

Antibodies

Nucleotide

Polypeptide

Other Information

Nucleotide

Polypeptide

Other Information

Antibodies

Nucleotide

Polypeptide

Other Information

Antibodies

Nucleotide

Polypeptide

Other Information

Antibodies

Nucleotide

Polypeptide

Official Symbol: ENG

Other Information

Nucleotide

Polypeptide

Other Information

Nucleotide

Polypeptide

Other Information

Official Symbol VCAM1

Antibody Sequences

The parent antibody may also be a fusion protein comprising an albumin-binding peptide (ABP) sequence (Dennis et al. (2002) “Albumin Binding As A General Strategy For Improving The Pharmacokinetics Of Proteins”J Biol Chem.277:35035-35043; WO 01/45746). Antibodies of the invention include fusion proteins with ABP sequences taught by: (i) Dennis et al (2002)J Biol Chem.277:35035-35043 at Tables III and IV, page 35038; (ii) US 2004/0001827 at [0076]; and (iii) WO 01/45746 at pages 12-13, and all of which are incorporated herein by reference.

In one embodiment, the antibody has been raised to target specific the tumour related antigen αvβ6.

The cell binding agent may be labelled, for example to aid detection or purification of the agent either prior to incorporation as a conjugate, or as part of the conjugate. The label may be a biotin label. In another embodiment, the cell binding agent may be labelled with a radioisotope.

Connection of Linker unit to Ligand unit

The Ligand unit is connected to the Linker unit through a disulfide bond.

In one embodiment, the connection between the Ligand unit and the Drug Linker is formed between a thiol group of a cysteine residue of the Ligand unit and a maleimide group of the Drug Linker unit.

The cysteine residues of the Ligand unit may be available for reaction with the functional group of the Linker unit to form a connection. In other embodiments, for example where the Ligand unit is an antibody, the thiol groups of the antibody may participate in interchain disulfide bonds. These interchain bonds may be converted to free thiol groups by e.g. treatment of the antibody with DTT prior to reaction with the functional group of the Linker unit.

In some embodiments, the cysteine residue is an introduced into the heavy or light chain of an antibody. Positions for cysteine insertion by substitution in antibody heavy or light chains include those described in Published U.S. Application No. 2007-0092940 and International Patent Publication WO2008070593, which are incorporated herein.

Methods of Treatment

The compounds of the present invention may be used in a method of therapy. Also provided is a method of treatment, comprising administering to a subject in need of treatment a therapeutically-effective amount of a conjugate of formula I. The term “therapeutically effective amount” is an amount sufficient to show benefit to a patient. Such benefit may be at least amelioration of at least one symptom. The actual amount administered, and rate and time-course of administration, will depend on the nature and severity of what is being treated. Prescription of treatment, e.g. decisions on dosage, is within the responsibility of general practitioners and other medical doctors.

A conjugate may be administered alone or in combination with other treatments, either simultaneously or sequentially dependent upon the condition to be treated. Examples of treatments and therapies include, but are not limited to, chemotherapy (the administration of active agents, including, e.g. drugs; surgery; and radiation therapy.

Pharmaceutical compositions according to the present invention, and for use in accordance with the present invention, may comprise, in addition to the active ingredient, i.e. a conjugate of formula I, a pharmaceutically acceptable excipient, carrier, buffer, stabiliser or other materials well known to those skilled in the art. Such materials should be non-toxic and should not interfere with the efficacy of the active ingredient. The precise nature of the carrier or other material will depend on the route of administration, which may be oral, or by injection, e.g. cutaneous, subcutaneous, or intravenous.

Pharmaceutical compositions for oral administration may be in tablet, capsule, powder or liquid form. A tablet may comprise a solid carrier or an adjuvant. Liquid pharmaceutical compositions generally comprise a liquid carrier such as water, petroleum, animal or vegetable oils, mineral oil or synthetic oil. Physiological saline solution, dextrose or other saccharide solution or glycols such as ethylene glycol, propylene glycol or polyethylene glycol may be included. A capsule may comprise a solid carrier such a gelatin.

The Conjugates can be used to treat proliferative disease and autoimmune disease. The term “proliferative disease” pertains to an unwanted or uncontrolled cellular proliferation of excessive or abnormal cells which is undesired, such as, neoplastic or hyperplastic growth, whether in vitro or in vivo.

Examples of proliferative conditions include, but are not limited to, benign, pre-malignant, and malignant cellular proliferation, including but not limited to, neoplasms and tumours (e.g., histocytoma, glioma, astrocyoma, osteoma), cancers (e.g. lung cancer, small cell lung cancer, gastrointestinal cancer, bowel cancer, colon cancer, breast carinoma, ovarian carcinoma, prostate cancer, testicular cancer, liver cancer, kidney cancer, bladder cancer, pancreatic cancer, brain cancer, sarcoma, osteosarcoma, Kaposi's sarcoma, melanoma), leukemias, psoriasis, bone diseases, fibroproliferative disorders (e.g. of connective tissues), and atherosclerosis. Other cancers of interest include, but are not limited to, haematological; malignancies such as leukemias and lymphomas, such as non-Hodgkin lymphoma, and subtypes such as DLBCL, marginal zone, mantle zone, and follicular, Hodgkin lymphoma, AML, and other cancers of B or T cell origin.

In some embodiments, the amount of the Conjugate administered ranges from about 0.01 to about 10 mg/kg per dose. In some embodiments, the amount of the Conjugate administered ranges from about 0.01 to about 5 mg/kg per dose. In some embodiments, the amount of the Conjugate administered ranges from about 0.05 to about 5 mg/kg per dose. In some embodiments, the amount of the Conjugate administered ranges from about 0.1 to about 5 mg/kg per dose. In some embodiments, the amount of the Conjugate administered ranges from about 0.1 to about 4 mg/kg per dose. In some embodiments, the amount of the Conjugate administered ranges from about 0.05 to about 3 mg/kg per dose.

In some embodiments, the amount of the Conjugate administered ranges from about 0.1 to about 3 mg/kg per dose. In some embodiments, the amount of the Conjugate administered ranges from about 0.1 to about 2 mg/kg per dose.

Drug Loading

The drug loading (p) is the average number of PBD drugs per cell binding agent, e.g. antibody. Where the compounds of the invention are bound to cysteines, drug loading may range from 1 to 8 drugs (D) per cell binding agent, i.e. where 1, 2, 3, 4, 5, 6, 7, and 8 drug moieties are covalently attached to the cell binding agent. Compositions of conjugates include collections of cell binding agents, e.g. antibodies, conjugated with a range of drugs, from 1 to 8. Where the compounds of the invention are bound to lysines, drug loading may range from 1 to 80 drugs (D) per cell binding agent, although an upper limit of 40, 20, 10 or 8 may be preferred. Compositions of conjugates include collections of cell binding agents, e.g. antibodies, conjugated with a range of drugs, from 1 to 80, 1 to 40, 1 to 20, 1 to 10 or 1 to 8.

The average number of drugs per antibody in preparations of ADC from conjugation reactions may be characterized by conventional means such as UV, reverse phase HPLC, HIC, mass spectroscopy, ELISA assay, and electrophoresis. The quantitative distribution of ADC in terms of p may also be determined. By ELISA, the averaged value of p in a particular preparation of ADC may be determined (Hamblett et al (2004)Clin. Cancer Res.10:7063-7070; Sanderson et al (2005) Clin. Cancer Res. 11:843-852). However, the distribution of p (drug) values is not discernible by the antibody-antigen binding and detection limitation of ELISA. Also, ELISA assay for detection of antibody-drug conjugates does not determine where the drug moieties are attached to the antibody, such as the heavy chain or light chain fragments, or the particular amino acid residues. In some instances, separation, purification, and characterization of homogeneous ADC where p is a certain value from ADC with other drug loadings may be achieved by means such as reverse phase HPLC or electrophoresis. Such techniques are also applicable to other types of conjugates.

For some antibody-drug conjugates, p may be limited by the number of attachment sites on the antibody. For example, an antibody may have only one or several cysteine thiol groups, or may have only one or several sufficiently reactive thiol groups through which a linker may be attached. Higher drug loading, e.g. p>5, may cause aggregation, insolubility, toxicity, or loss of cellular permeability of certain antibody-drug conjugates.

Typically, fewer than the theoretical maximum of drug moieties are conjugated to an antibody during a conjugation reaction. An antibody may contain, for example, many lysine residues that do not react with the Drug Linker (A or B). Only the most reactive lysine groups may react with an amine-reactive linker reagent. Also, only the most reactive cysteine thiol groups may react with a thiol-reactive linker reagent. Generally, antibodies do not contain many, if any, free and reactive cysteine thiol groups which may be linked to a drug moiety. Most cysteine thiol residues in the antibodies of the compounds exist as disulfide bridges and must be reduced with a reducing agent such as dithiothreitol (DTT) or TCEP, under partial or total reducing conditions. The loading (drug/antibody ratio) of an ADC may be controlled in several different manners, including: (i) limiting the molar excess of Drug Linker (A or B) relative to antibody, (ii) limiting the conjugation reaction time or temperature, and (iii) partial or limiting reductive conditions for cysteine thiol modification.

Certain antibodies have reducible interchain disulfides, i.e. cysteine bridges. Antibodies may be made reactive for conjugation with linker reagents by treatment with a reducing agent such as DTT (dithiothreitol). Each cysteine bridge will thus form, theoretically, two reactive thiol nucleophiles. Additional nucleophilic groups can be introduced into antibodies through the reaction of lysines with 2-iminothiolane (Traut's reagent) resulting in conversion of an amine into a thiol. Reactive thiol groups may be introduced into the antibody (or fragment thereof) by engineering one, two, three, four, or more cysteine residues (e.g., preparing mutant antibodies comprising one or more non-native cysteine amino acid residues). U.S. Pat. No. 7,521,541 teaches engineering antibodies by introduction of reactive cysteine amino acids.

Cysteine amino acids may be engineered at reactive sites in an antibody and which do not form intrachain or intermolecular disulfide linkages (Junutula, et al., 2008b Nature Biotech., 26(8):925-932; Dornan et al (2009) Blood 114(13):2721-2729; U.S. Pat. Nos. 7,521,541; 7,723,485; WO2009/052249). The engineered cysteine thiols may react with linker reagents or the drug-linker reagents of the present invention which have thiol-reactive, electrophilic groups such as maleimide or alpha-halo amides to form ADC with cysteine engineered antibodies and the PBD drug moieties. The location of the drug moiety can thus be designed, controlled, and known. The drug loading can be controlled since the engineered cysteine thiol groups typically react with thiol-reactive linker reagents or drug-linker reagents in high yield. Engineering an IgG antibody to introduce a cysteine amino acid by substitution at a single site on the heavy or light chain gives two new cysteines on the symmetrical antibody. A drug loading near 2 can be achieved with near homogeneity of the conjugation product ADC.

Where more than one nucleophilic or electrophilic group of the antibody reacts with a drug-linker intermediate, or linker reagent followed by drug moiety reagent, then the resulting product is a mixture of ADC compounds with a distribution of drug moieties attached to an antibody, e.g. 1, 2, 3, etc. Liquid chromatography methods such as polymeric reverse phase (PLRP) and hydrophobic interaction (HIC) may separate compounds in the mixture by drug loading value. Preparations of ADC with a single drug loading value (p) may be isolated, however, these single loading value ADCs may still be heterogeneous mixtures because the drug moieties may be attached, via the linker, at different sites on the antibody.

Thus the antibody-drug conjugate compositions of the invention include mixtures of antibody-drug conjugate compounds where the antibody has one or more PBD drug moieties and where the drug moieties may be attached to the antibody at various amino acid residues.

In one embodiment, the average number of dimer pyrrolobenzodiazepine groups per cell binding agent is in the range 1 to 20. In some embodiments the range is selected from 1 to 8, 2 to 8, 2 to 6, 2 to 4, and 4 to 8.

In some embodiments, there is one dimer pyrrolobenzodiazepine group per cell binding agent.

General Synthetic Routes

The synthesis of PBD compounds is extensively discussed in the following references, which discussions are incorporated herein by reference:

Synthesis Route

The Drug Linker compounds of the present invention (A and B) may be synthesised according to the Examples.

Synthesis of Drug Conjugates

Conjugates can be prepared as previously described. Antibodies can be conjugated to the Drug Linker compounds (A or B) as described in Doronina et al., Nature Biotechnology, 2003, 21, 778-784). Briefly, antibodies (4-5 mg/mL) in PBS containing 50 mM sodium borate at pH 7.4 are reduced with tris(carboxyethyl)phosphine hydrochloride (TCEP) at 37° C. The progress of the reaction, which reduces interchain disulfides, is monitored by reaction with 5,5′-dithiobis(2-nitrobenzoic acid) and allowed to proceed until the desired level of thiols/mAb is achieved. The reduced antibody is then cooled to 0° C. and alkylated with 1.5 equivalents of maleimide drug-linker per antibody thiol. After 1 hour, the reaction is quenched by the addition of 5 equivalents of N-acetyl cysteine. Quenched drug-linker is removed by gel filtration over a PD-10 column. The ADC is then sterile-filtered through a 0.22 μm syringe filter. Protein concentration can be determined by spectral analysis at 280 nm and 329 nm, respectively, with correction for the contribution of drug absorbance at 280 nm. Size exclusion chromatography can be used to determine the extent of antibody aggregation, and RP-HPLC can be used to determine the levels of remaining NAC-quenched drug-linker.

Further Preferences

The following preferences may apply to all aspects of the invention as described above, or may relate to a single aspect. The preferences may be combined together in any combination.

In some embodiments, the C11 substituent may be in the following stereochemical arrangement relative to neighbouring groups:

In other embodiments, the C11 substituent may be in the following stereochemical arrangement relative to neighbouring groups:

In one embodiment of the present invention, the compound of formula III is A.

In one embodiment of the present invention, the compound of formula III is B.

In one embodiment of the present invention, the Drug Linker unit of formula III is DL-A.

In one embodiment of the present invention, the Drug Linker unit of formula III is DL-B.

EXAMPLES

Reaction progress was monitored by thin-layer chromatography (TLC) using Merck Kieselgel 60 F254 silica gel, with fluorescent indicator on aluminium plates. Visualisation of TLC was achieved with UV light or iodine vapour unless otherwise stated. Flash chromatography was performed using Merck Kieselgel 60 F254 silica gel. Extraction and chromatography solvents were bought and used without further purification from VWR, U.K. All chemicals were purchased from Aldrich.

Proton NMR chemical shift values were measured on the delta scale at 400 MHz using a Bruker AV400. The following abbreviations have been used: s, singlet; d, doublet; t, triplet; q, quartet; quin, quintet; m, multiplet; br, broad. Coupling constants are reported in Hz. Column chromatography was performed on an Isolera (Biotage) automated system using normal phase SNAP cartridges.

The LC/MS conditions were as follow:

LCMS data were obtained using a Shimadzu Nexera series LC/MS with a Shimadzu LCMS-2020 quadrupole MS, with Electrospray ionisation. Mobile phase A—0.1% formic acid in water. Mobile phase B—0.1% formic acid in acetonitrile.

Short run gradient: initial composition was 5% B held over 0.25 min, then increase from 5% B to 100% B over a 2 min period. The composition was held for 0.50 min at 100% B, then returned to 5% B in 0.05 minutes and hold there for 0.05 min. Total gradient run time equals 3 min. Flow rate 0.8 mL/min. Wavelength detection range: 190 to 800 nm. Oven temperature: 50° C. Column: Waters Acquity UPLC BEH Shield RP18 1.7 μm 2.1×50 mm. Long run gradient: initial composition 5% B held over 1 min, then increase from 5% B to 100% B over a 9 min period. The composition was held for 2 min at 100% B, then returned to 5% B in 0.10 minutes and hold there for 3 min. Total gradient run time equals 15 min.

Commercially available proline derivative (1) was obtained from Omegachem

Potassium carbonate (19.92 g, 14 mmol, 3.0 eq.) was added to a stirred solution of the carboxylic acid 1 (10.92 g, 48 mmol, 1.0 eq.) in DMF (270 mL). The resulting white suspension was stirred at room temperature for 30 mins, at which point iodomethane (21.48 g, 9.5 mL, 151 mmol, 3.15 eq.) was added. The reaction mixture was allowed to stir at room temperature for 3 days. The DMF was removed by rotary evaporation under reduced pressure to afford a yellow residue which was partitioned between ethylacetate and water. The organic layer was separated and the aqueous phase was extracted with ethylacetate. The combined organic layers were washed with water brined and dried over magnesium sulphate. The ethylacetate was removed by rotary evaporation under reduced pressure to give the crude product as a yellow oil. The crude product was purified by flash chromatography [85% n-hexane/15% ethylacetate] to afford the product as a colourless oil (10.74 g, 93%).

A solution of 4 M hydrochloric acid in dioxane (63 mL, 254.4 mmol, 4.5 eq.) was added to the Boc protected C-ring fragment 2 (13.67 g, 56.6 mmol, 1.0 eq.) at room temperature. Effervescence was observed indicating liberation of CO2and removal of the Boc group. The product precipitated as a white solid and additional dioxane was added to facilitate stirring the reaction mixture was allowed to stir for an hour and then diluted with diethyl ether. The precipitated product was collected by vacuum filtration and washed with additional diethyl ether. Air drying afforded the desired product as a white powder (9.42 g, 94%).

Solid Cu(NO3)2.3H2O(81.54 g, 337.5 mmol) was added slowly to an overhead stirred slurry of the bis-ester 5 (54.68 g, 135 mmol) in acetic anhydride (650 mL) at 0-5° C. (ice/acetone). The reaction mixture was allowed to stir for 1 h at 0-5° C. and then allowed to warm to room temperature. A mild exotherm (c. 40-50° C.), accompanied by thickening of the mixture and evolution of NO2was observed at this stage. Additional acetic anhydride (300 mL) was added and the reaction mixture was allowed to stir for 16 h at room temperature. The reaction mixture was poured onto ice (˜1.5 L), stirred and allowed to return to room temperature. The resulting yellow precipitate was collected by vacuum filtration and dried in a desiccator to afford the desired bis-nitro compound 6 as a yellow solid. Yield=66.7 g (100%). Analytical Data: Purity satisfactory by LC/MS 3.25 min (ES+) m/z (relative intensity) 517 ([M+Na]+, 40);1H NMR (400 MHz, CDCl3) δ 7.49 (s, 2H), 7.06 (s, 2H), 4.32 (t, 4H, J=6.0 Hz), 3.95 (s, 6H), 3.90 (s, 6H), 2.45-2.40 (m, 2H). See ref Thurston 1996.

A slurry of the methyl ester 6 (66.7 g, 135 mmol) in THF (700 mL) was treated with 1N NaOH (700 mL) and the reaction mixture was allowed to stir vigorously at room temperature. After 4 days stirring, the slurry became a dark coloured solution which was subjected to rotary evaporation under reduced pressure to remove THF. The resulting aqueous residue was acidified to pH 1 with concentrated HCl and the colourless precipitate 7 was collected and dried thoroughly in a vacuum oven (50° C.). Yield=54.5 g (87%). Analytical Data: Purity satisfactory by LC/MS 2.65 min (ES+) m/z (relative intensity) 489 ([M+Na]+, 30);1H NMR (400 MHz, DMSO-d6) δ 7.62 (s, 2H), 7.30 (s, 2H), 4.29 (t, 4H, J=6.0 Hz), 3.85 (s, 6H), 2.30-2.26 (m, 2H).

A catalytic amount of anhydrous DMF (2.4 mL) was added to a stirred suspension of oxalyl chloride (14.7 g, 9.8 mL, 115.8 mmol, 3 eq.) and dimer core 7 (18 g, 38.6 mmol, 1 eq.) in anhydrous DCM (500 mL) at room temperature. Vigorous effervescence was observed after the addition of DMF and the reaction mixture was allowed to stir for 18 h in a round bottom flask fitted with a calcium chloride drying tube. The resulting clear solution was evaporated under reduced pressure and the solid triturated with ether. The solid product was collected by vacuum filtration, washed with additional ether and dried in vacuo at 40° C. for 1.5 h. This solid was then added portion wise to a suspension of the C-ring 3 (15.1 g, 84.9 mmol, 2.2 eq.) and TEA (19.5 g, 27 ml, 119.6 mmol, 5 eq.) in dry DCM (375 mL), maintaining the temperature between −40 and −50° C. with the aid of a dry ice/acetonitrile bath. The reaction mixture was allowed to stir at −40° C. for 1 h and then allowed to warm to room temperature at which point LCMS indicated the complete consumption of the starting material. The reaction mixture was diluted with additional DCM and washed sequentially with aqueous hydrochloric acid (1M, 2×200 mL), saturated aqueous sodium bicarbonate (2×250 mL), water (250 mL), brine (250 mL), dried (MgSO4). DCM was removed by rotary evaporation under reduced pressure to afford the product as a yellow foam (25.72 g, 94%). Analytical Data: RT 1.59 min; MS (ES+) m/z (relative intensity) 713 ([M+H]+, 100)

Solid lithium borohydride (3.18 g, 146 mmol, 3 eq.) was added in one portion to a solution of the ester 8 (34.72 g, 48.7 mmol, 1 eq.) in dry THF (350 mL) under a nitrogen atmosphere at 0° C. (ice bath). The reaction mixture was allowed to stir at 0° C. for 30 mins and then allowed to warm to room temperature at which point precipitation of an orange gum was observed. The reaction mixture was allowed to stir at room temperature for a futher 2 hours and then cooled in an ice bath and treated with water to give a yellow suspension. Hydrochloric acid (1M) was carefully added until effervescence ceased. The reaction mixture was extracted with ethylacetate (×4) and the combined organic layers were washed with water (×1), brine (×1) and dried (MgSO4). Ethylacetate was removed by rotary evaporation under reduced pressure to give a yellow foam. Purification by flash column chromatography [gradient elution DCM/MeOH 0% to 5% in 1% increments] gave the product as a pale yellow foam (23.1 g, 72%). Analytical Data: RT 1.23 min; MS (ES+) m/z (relative intensity) 657 ([M+H]+, 100)

A solution of the bis-alcohol 9 (10 g, 15.2 mmol, 1 eq.), t-butyldimethylsilylchloride (5.97 g, 39.6 mmol, 2.6 eq.) and imidazole (5.38 g, 79 mmol, 5.2 eq.) in dry DMF (80 ml) was stirred at room temperature for 3h. The reaction mixture was poured into water (500 mL) to give a yellow precipitate. The mixture was extracted with DCM (4×100 mL) and the combined extracts were washed with water and brine, dried (MgSO4) and evaporated under reduced pressure to give a viscous yellow oil. Purification by column chromatography [biotage isolera, gradient elution hexane 60%/EtOAc 40% to EtOAc 100%, 8 column volumes 100 g snap ultra® cartridge] gave the product as a yellow foam (11.8 g, 88%). Analytical Data: RT 2.20 min; MS (ES+) m/z (relative intensity) 885 ([M+H]+, 100), 907 ([M+Na]+, 50)

Zinc powder (31.9 g, 488 mmol, 40 eq.) was activated by stirring/sonication with 1M HCl for 10 min. The Zinc was filtered washing with 1M HCl, water (×3) and MeOH (×2). The activated Zinc was added to a solution of the nitro-TBS compound 10 (10.8 g, 12.2 mmol, 1 eq.) in MeOH (88 mL) and 5% formic acid/MeOH solution (440 mL). The temperature rose to 37° C. and the reaction mixture changed from a yellow to a colourless solution. Once the exotherm had subsided (20 min.) the reaction was shown to be complete by LCMS. The reaction mixture was filtered through celite washing with EtOAc. The EtOAc portion was washed with saturated bicarbonate solution (×4) [caution effervescence!], water (×1), brine (×1), dried (MgSO4) and evaporated under reduced pressure to give a yellow solid.

A solution of the bis-aniline 11 (3.27 g, 3.96 mmol) and di-t-butyldicarbonate (0.85 g, 3.96 mmol) in dry THF (125 mL) were heated under reflux for 24 h. The reaction mixture was cooled and the solvent evaporated under reduced pressure. The residue was purified by flash column chromatography [n-hexane/EtOAc 50/50 v/v to EtOAc 100% in 10% increments then EtOAc/MeOH 98/2 v/v] to give the desired product as a yellow foam (1.63 g, 44%). Analytical Data: RT 2.28 min; MS (ES+) m/z (relative intensity) 925 ([M+H]+, 70), 947 ([M+Na]+, 100)

Allyl chloroformate (41 g, 36.2 mL, 0.34 mol, 1.2 eq.) was added dropwise to a stirred solution of L-valine 13 (33.25 g, 0.28 mol, 1 eq.) and potassium carbonate (58.9 g, 0.426 mol, 1.5 eq.) in water (650 mL) and THF (650 mL). The reaction mixture was stirred at room temperature for 18 h. The THF was evaporated under reduced pressure and the remaining solution was extracted with diethyl ether (or MTBE) (×2). The aqueous portion was acidified to pH 2 with conc. HCl and extracted with DCM (×3). The combined organic extracts were washed with brine (×1), dried (MgSO4) and evaporated under reduced pressure to give a colourless oil (57.1 g). This was used in the next step without further purification.

To a stirred solution of compound 14 (57.1 g, 0.28 mol, 1 eq.) and N-hydroxysuccinimide (32.68 g, 0.28 mol, 1 eq.) in dry THF (800 mL) was added dicyclohexylcarbodiimide (58.6 g, 0.28 mol, 1 eq.). The reaction mixture was stirred at room temperature for 18h. The reaction mixture was filtered. The solid was washed with THF and the combined filtrate was concentrated under reduced pressure. The oil/solid residue was re-dissolved in DCM and left to stand at 0° C. for 30 min. The suspension was filtered washing with cold DCM. Evaporation of the filtrate under reduced pressure gave the succinimide ester as a white solid which was used in the next step without further purification.

A solution of Alloc-Val-OSu 15 (11.67 g, 39.0 mmol, 1 eq.) in THF (50 mL) was added to a solution of H-Ala-OH (3.66 g, 41.08 mmoL, 1.05 eq.) and NaHCO3(3.61 g, 43.03 mmol, 1.1 eq.) in THF (100 mL) and H2O (100 mL). The mixture was stirred at room temperature for 72 h and the THF was evaporated under reduced pressure. The pH was adjusted to 3-4 with citric acid to precipitate a white gum. This was extracted with ethylacetate (6×150 mL) and the combined extracts were washed with H2O (200 mL), brine (200 mL), dried (MgSO4) and evaporated under reduced pressure to give a white solid. Trituration with diethyl ether (xs) afforded the pure product as a white powder (7.93 g, 74%). Analytical Data: RT 2.17 min; MS (ES+) m/z (relative intensity) 295 ([M+Na]+, 63), 273 ([M+1]+, 60).

EEDQ (4.79 g, 19.3 mmol, 1.05 eq.) was added to a solution of p-aminobenzyl alcohol (2.38 g, 19.3 mmol, 1.05 eq.) and Alloc-Val-Ala-OH 16 (5.02 g, 18.4 mmol, 1.0 eq) in dry THF (100 mL). The mixture was stirred at room temperature for 72 h. The solvent was evaporated under reduced pressure to give a pale brown solid. The solid was triturated with diethyl ether and filtered washing with an excess of diethyl ether. This afforded the product as a white solid (6.2 g, 89%). Analytical Data: RT 2.50 min; MS (ES+) m/z (relative intensity) 400.6 ([M+Na]+, 50), 378.6 ([M+1]+, 60).

Triethylamine (0.38 g, 0.53 mL, 3.8 mmol, 2.2 eq.) was added to a stirred solution of the mono-boc protected bis-aniline (12) (1.6 g, 1.72 mmol, 1.0 eq.) and triphosgene (0.184 g, 0.62 mmol. 0.36 eq.) in dry THF (25 mL) under a nitrogen atmosphere at room temperature. The reaction mixture was heated to 40° C., after 5 min a sample was treated with methanol and analysed by LCMS as the methyl carbamate. Analytical Data: RT 2.32 min; MS (ES+) m/z (relative intensity) 983 ([M+H]+, 55), 1005 ([M+Na]+, 100) A solution/suspension of the benzyl-alcohol (17) (1.52 g, 2.35 mmol, 1.4 eq.) and triethylamine (0.26 g, 0.36 mL 2.6 mmol, 1.5 eq.) in dry THF (40 mL) was run in from a dropping funnel to the freshly prepared isocyanate. The reaction mixture was stirred at 40° C. for 2.5 h. The reaction mixture was allowed to cool, filtered and the filtrate evaporated to dryness to afford the crude product as a yellow oil which was purified by flash column chromatography [n-hexane/EtOAc 50/50 v/v] which gave the product as a yellow glass (1.192 g). The mixed fractions were purified by flash column chromatography [CHCl3/MeOH 0% to 1%] to give a further amount of product (0.22 g). The material was combined to give the product as a yellow foam (1.41 g, 63%). Analytical Data: RT 2.27 min; MS (ES+) m/z (relative intensity) 1328 ([M+H]+,30), 1350 ([M+Na]+, 100)

A 1.0M solution of TBAF in THF (2.34 mL, 2.34 mmol, 2.2 eq.) was added to a solution of the bis-TBS compound (18) (1.41 g, 1.06 mmol, 1.0 eq.) in anhydrous THF (12 mL). The mixture was stirred at room temperature for 30 min., the solvent was removed under reduced pressure and the residue purified by flash column chromatography [CHCl3/MeOH 0% to 4% in 1% increments] to give the desired product as a white foam (0.98 g, 84%). Analytical Data: RT 1.62 min; MS (ES+) m/z (relative intensity) 1100 ([M+H]+,60), 1122 ([M+Na]+, 100)

IBX (45 wt %, 1.3 g, 2.09 mmol, 2.4 eq.) was added to a solution of the bis-alcohol 19 (0.959 g, 0.87 mmol, 1.0 eq.) in anhydrous DMSO (25 mL). The solution was stirred at 30° C. for 18h. LCMS analysis indicated the presence of a small amount of partially cyclised material. A further portion of IBX (45 wt %, 0.049 g, 0.17 mmol, 0.2 eq.) was added and the reaction was continued for a further 18 h. The reaction mixture was poured into water (200 mL) and the resultant precipitate was collected by filtration washing with water. The precipitate was dissolved in DCM (150 mL) and washed with saturated NaHCO3(100 mL), water (100 mL) and brine (100 mL). The organic portion was dried (MgSO4) and evaporated to give a white solid. Purification by flash column chromatography [CHCl3/MeOH 0% to 4% in 1% increments] gave the product as a white solid (0.696 g, 73%). Analytical Data: RT 1.55 min; MS (ES+) m/z (relative intensity) 1096 ([M+H]+,20), 1118 ([M+Na]+, 100)

Ice cold 95% TFA(aq)solution (10 mL) was added to the Boc protected compound 22 (0.759 g, 0.48 mmol, 1.0 eq) which had been cooled to 0° C. (ice bath). The yellow solution was stirred at 0° C. for 1h. The reaction mixture was poured onto ice/water (200 mL) and the mixture was basified to pH 8 with solid NaHCO3. The mixture was extracted with DCM (4×50 mL) and the combined extracts washed with brine (100 mL), dried (MgSO4) and evaporated under reduced pressure. The product was purified by flash column chromatography [CHCl3/MeOH 0% to 8% in 1% increments] to give a pale yellow foam (0.445 g, 65%). Analytical Data: RT 1.37 min; MS (ES+) m/z (relative intensity) 1468 ([M+H]+,40)

A 10% solution of formic acid in methanol (500 mL) was added in one go, via a separating funnel, to a solution of the bis-alcohol (24) (66 g, 0.09 mol) in methanol (1000 mL) containing zinc* (145 g, 2.22 mol) at room temperature. The temperature of the reaction mixture rapidly rose to 42° C. and was then cooled back to room temperature with the aid of a cold water bath. The excess zinc was removed by filtering through a short bed of celite, which was then washed with ethyl acetate (100 mL). The filtrate was diluted with ethyl acetate (1400 mL) and washed with saturated sodium hydrogen carbonate (1500 mL), water (500 mL), brine (100 mL) and dried (MgSO4). Removal of the solvent by rotary evaporation gave a yellow solid which was purified by column chromatography (4% methanol/DCM) to give the product as a pale yellow foam. Yield=38.1 g (63%). Analytical Data: Purity satisfactory by LC/MS (6.61 min (ES+) m/z (relative intensity) 681.2 ([M+1]+, 100));1H NMR (400 MHz, CDCl3) δ δ6.74 (s, 2H), 6.31 (s, 2H), 5.02 (bs, 2H), 4.97 (bs, 2H), 4.80 (s, 2H), 4.33-4.10 (m, 16H), 3.78 (s, 3H), 2.78 (m, 2H), 2.46 (m, 2H), 2.34 (m, 2H), 2.04 (s, 6H).

Triethyl amine (0.57 g, 5.6 mmol) was added in one go to a solution of the amine (26) (2 g, 2.56 mmol) and triphosgene (0.27 g, 0.92 mmol) in THF (30 mL) under nitrogen. The resulting mixture was heated at 40° C. for 5 min. A small aliquot was quenched with methanol, and LCMS indicated complete conversion to the methyl carbamate (m/z 983, M+1). A slurry of SG3366 (2.25 g, 3.48 mmol) and triethyl amine (0.39 g, 3.84 mmol) in THF (50 mL) was added in one go and the resulting mixture heated at 40° C. for 4 hours.

A solution/suspension of the benzyl-alcohol (17) (3.11 g, 8.25 mmol, 1.5 eq.) and triethylamine (0.83 g, 1.1 mL 2.6 mmol, 1.5 eq.) in dry THF (75 mL) was run in from a dropping funnel to the freshly prepared isocyanate. The reaction mixture was stirred at 40° C. for 5h. then overnight at room temperature The reaction mixture was allowed to cool, filtered and the filtrate evaporated to dryness to afford the crude product as a yellow oil which was purified by flash column chromatography [50% n-hexane/50% ethyl acetate to 40% n-hexane/60% ethyl acetate] which gave the product as a yellow glass (1.25 g, 17%). Analytical Data: RT 2.26 min; MS (ES+) m/z (relative intensity) 1312 ([M+H]+, 25), 1335 ([M+Na]+, 35)

A 1.0M solution of TBAF in THF (5.2 mL, 5.2 mmol, 2.2 eq.) was added to a solution of the bis TBS compound (29) (3.096 g, 2.36 mmol, 1.0 eq.) in anhydrous THF (25 mL). The mixture was stirred at room temperature for 30 min., the solvent was removed under reduced pressure and the residue purified by flash column chromatography [ethyl acetate/methanol 0% to 6% in 1% increments] which gave the desired product as a white foam (1.91 g, 75%). Analytical Data: RT 1.56 min; MS (ES+) m/z (relative intensity) 1084 ([M+H]+, 100), 1106 ([M+Na]+, 90)

IBX (45 wt %, 2.06 g, 3.3 mmol, 2.4 eq.) was added to a solution of the bis-alcohol 30 (1.49 g, 1.38 mmol, 1.0 eq.) in anhydrous DMSO (40 mL). The solution was stirred at 30° C. for 18h. LCMS analysis indicated the presence of a small amount of partially cyclised material. A further portion of IBX (45 wt %, 0.171 g, 0.275 mmol, 0.2 eq.) was added and the reaction was continued for a further 24 h. The reaction mixture was poured into water (200 mL) and the resultant precipitate was collected by filtration washing with water. The precipitate was dissolved in DCM (150 mL) and washed with saturated NaHCO3(100 mL), water (100 mL) and brine (100 mL). The organic portion was dried (MgSO4) and evaporated to give a white solid. Purification by flash column chromatography [CHCl3/MeOH 0% to 3% in 1% increments] gave the product as a white solid (1.06 g, 72%). Analytical Data: RT 6.88 min; MS (ES+) m/z (relative intensity) 1080 ([M+H]+, 50), 1102 ([M+Na]+, 100)

Pd(PPh3)4(44 mg, 38.5 μmol, 0.04 eq.) was added to a solution of the cyclised product 31 (1.04 g, 0.96 mmol, 1.0 eq.) and pyrrolidine (0.171 mg, 196 μL, 2.4 mmol, 2.5 eq.) in anhydrous DCM (30 mL). The solution was stirred at room temperature for 30 min. The reaction mixture was diluted with DCM (30 mL) and washed with saturated NH4Cl (100 mL), saturated brine (100 mL), dried (MgSO4) and evaporated to give an off white foam. The product was triturated with diethyl ether and dried to give the product (0.86 g, 100%) which was used without further purification. Analytical Data: RT 1.10 min; MS (ES+) m/z (relative intensity) 894 ([M+H]+, 30)

EDCI.HCl (0.203 g, 1.06 mmol, 1.1 eq.) was added to a solution of compound 32 (0.86 g, 0.96 mmol, 1.0 eq.) and Mal-dPEG8®-OH (0.57 g, 0.96 mmol, 1.1 eq.) in dry DCM (30 mL) and CHCl3(to give a clear solution). The clear solution was stirred at room temperature for 18h. then a further portion of EDCI.HCl (0.037 g, 0.19 mmol, 0.2 eq.) was added and reaction continued for a further 24h. The reaction mixture was diluted with DCM (70 mL) washed with water (100 mL), brine (100 mL), dried (MgSO4) and evaporated under reduced pressure to give a yellow foam. Purification by flash column chromatography [CHCl3/MeOH 0% to 6% in 1% increments] gave the product as an off white foam (0.56 g, 40%). Analytical Data: RT 6.13 min; MS (ES+) m/z (relative intensity) 1468 ([M+H]+, 20)

A solution/suspension of the benzyl-alcohol (33) (0.121 g, 0.29 mmol, 1.3 eq.) and triethylamine (0.029 g, 0.04 mL 0.29 mmol, 1.3 eq.) in dry THF (5 mL) was run in from a dropping funnel to the freshly prepared isocyanate. The reaction mixture was stirred at 40° C. for 4h. then overnight at room temperature The reaction mixture was allowed to cool, filtered and the filtrate evaporated to dryness to afford the crude product which was purified by flash column chromatography [Biotage Isolera™ CHCl3/MeOH 2% to 4%, gradient elution]. This gave the product (0.237 g, 79%). Analytical Data: RT 2.19 min; MS (ES+) m/z (relative intensity) 1358 ([M+H]+, 30), 1380 ([M+Na]+, 15)

Pd(PPh3)4(0.3 g, 0.25 mmol, 0.06 eq.) was added to a solution of the alloc protected intermediate 34 (5.89 g, 4.3 mmol, 1.0 eq.) and pyrrolidine (0.46 g, 530 μL, 6.5 mmol, 1.5 eq.) in anhydrous DCM (50 mL). The solution was stirred at room temperature for 1h. The reaction mixture was diluted with DCM and washed with saturated NH4Cl, saturated brine, dried (MgSO4) and evaporated to give crude product. The product was purified by flash column chromatography [Biotage Isolera™ DCM/MeOH 1% to 3%] to give the product (4.53 g, 83%) which had an overall purity of 80% and was used without further purification. Analytical Data: RT 2.10 min; MS (ES+) m/z (relative intensity) 1275 ([M+H]+, 40).

A solution/suspension of the benzyl-alcohol (17) (0.071 g, 0.19 mmol, 1.2 eq.) and triethylamine (19 mg, 26 μL 0.19 mmol, 1.2 eq.) in dry THF (5 mL) was run in from a dropping funnel to the freshly prepared isocyanate. The reaction mixture was stirred at 40° C. for 4 h. then overnight at room temperature The reaction mixture was filtered and the filtrate evaporated to dryness to afford the crude product which was purified by flash column chromatography [Biotage Isolera™ CHCl3/MeOH 2% to 3%, gradient elution] which gave the product (0.152 g, 58%). Analytical Data: RT 2.12 min; MS (ES+) m/z (relative intensity) 1677 ([M+H]+, 30), 1700 ([M+Na]+, 100).

A 1.0M solution of TBAF in THF (3.4 mL, 3.4 mmol, 2.0 eq.) was added to a solution of the bis TBS compound (36) (2.86 g, 1.7 mmol, 1.0 eq.) in anhydrous THF (30 mL) under an argon atmosphere. The mixture was stirred at room temperature for 6h., the reaction mixture was diluted with CHCl3and washed with water, brine, dried (MgSO4) and evaporated under reduced pressure to give a yellow solid. The residue was purified by flash column chromatography [Biotage Isolera™ CHCl3/MeOH, gradient elution with the product eluting at 4% MeOH] which gave the desired product (1.365 g) and mixed fractions which were further purified by flash column chromatography [CHCl3/MeOH 1% to 5%] to give further product (0.562 g) this gave a combined yield of desired product (1.93 g, 75%). Analytical Data: RT 1.55 min; MS (ES+) m/z (relative intensity) 1449 ([M+1]+, 25); 1471 ([M+Na]+, 20).

IBX (45 wt %, 0.236 g, 0.38 mmol, 2.2 eq.) was added to a solution of the bis-alcohol 37 (0.25 g, 0.17 mmol, 1.0 eq.) in anhydrous DMSO (12 mL). The solution was stirred at 30° C. for 3.5 d. The reaction mixture was poured into water (100 mL) and the resultant precipitate was collected by filtration washing with water. The precipitate was extracted with DCM (5×30 mL) and the combined fractions were washed with saturated NaHCO3(60 mL), water (60 mL) and brine (60 mL). The organic portion was dried (MgSO4) and evaporated to give crude product. Purification by flash column chromatography [CHCl3/MeOH 1% to 5%] gave the product as a white solid (0.158 g, 64%). Analytical Data: RT 1.53 min; MS (ES+) m/z (relative intensity) 1445 ([M+1]+, 20); 1467 ([M+Na]+, 30).

A 50 mM solution of tris(2-carboxyethyl)phosphine hydrochloride (TCEP) in phosphate-buffered saline pH 7.4 (PBS) was added (50 molar equivalent/antibody, 35 micromoles, 700 L) to a 24.14 mL solution of antibody, trastuzumab, (105 mg, 700 nanomoles) in reduction buffer containing PBS and 1 mM ethylenediaminetetraacetic acid (EDTA) and a final antibody concentration of 4.35 mg/mL. The reduction mixture was heated at +37° C. for 3 hours (or until full reduction is observed by UHPLC) in an incubator with gentle (<150 rpm) shaking. After cooling down to room temperature, the reduced antibody was buffer exchanged, via spin filter centrifugation, into a reoxidation buffer containing PBS pH 7.4 and 1 mM EDTA to remove all the excess reducing agent. A 50 mM solution of dehydroascorbic acid (DHAA, 10 molar equivalent/antibody, 7 micromoles, 140 μL) in DMSO was added and the reoxidation mixture was allowed to react for 16 hours at room temperature with gentle (<150 rpm) shaking at an antibody concentration of 2.3 mg/mL (or more DHAA added and reaction left for longer until full reoxidation of the cysteine thiols to reform the inter-chain cysteine disulfides is observed by UHPLC). The reoxidation mixture was then sterile-filtered and diluted in a conjugation buffer containing PBS pH 7.4, 1 mM EDTA for a final antibody concentration of 1.0-1.5 mg/mL. Compound 23 (SG3400) was added as a DMSO solution (10 molar equivalent/antibody, 1 micromole, in 1.0 mL DMSO) to 9 mL of this reoxidised antibody solution (15 mg, 100 nanomoles) for a 10% (v/v) final DMSO concentration. The solution was mixed for 1.5 hours at room temperature, then the conjugation was quenched by addition of N-acetyl cysteine (4 micromoles, 40 μL at 100 mM), diluted to >50 mL in PBS and conjugate trastuzumab-23 was purified by spin filtration using a 15 mL Amicon Ultracell 50 kDa MWCO spin filter, sterile-filtered and analysed. UHPLC analysis on a Shimadzu Prominence system using a Phenomenex Aeris 3.6u XB-C18 150 mm×2.1 mm column eluting with a gradient of water and acetonitrile on a reduced sample of conjugate trastuzumab-A at 280 nm and 330 nm (Compound A specific) shows unconjugated light chains and a mixture of unconjugated heavy chains and heavy chains attached to a single molecule of compound 23, consistent with a drug-per-antibody ratio (DAR) of 1.71 molecules of compound 23 per antibody.

UHPLC analysis on a Shimadzu Prominence system using a Tosoh Bioscience TSKgel G3000SWXL 5 μm 7.8×300 mm column (with a 7 μm 6.0×40 mm guard column) eluting with sterile-filtered SEC buffer containing 200 mM potassium phosphate pH 6.95, 250 mM potassium chloride and 10% isopropanol (v/v) on a sample of conjugate trastuzumab-23 at 280 nm shows a monomer purity of 94%. UHPLC SEC analysis gives a concentration of final conjugate trastuzumab-23 at 0.84 mg/mL in 15 mL, obtained mass of conjugate trastuzumab-23 is 12.7 mg (84% yield).

A 50 mM solution of tris(2-carboxyethyl)phosphine hydrochloride (TCEP) in phosphate-buffered saline pH 7.4 (PBS) was added trastuzumab, (50 molar equivalent/antibody, 50 micromoles, 1.0 mL) to a 34.5 mL solution of antibody (150 mg, 1.0 micromole) in reduction buffer containing PBS and 1 mM ethylenediaminetetraacetic acid (EDTA) at a final antibody concentration of 4.35 mg/mL. The reduction mixture was heated at +37° C. for 3 hours (or until full reduction is observed by UHPLC) in an incubator with gentle (<150 rpm) shaking. After cooling down to room temperature, the reduced antibody was buffer exchanged, via spin filter centrifugation, into a reoxidation buffer containing PBS and 1 mM EDTA to remove excess reducing agent. A 50 mM solution of dehydroascorbic acid (DHAA, 50 molar equivalent/antibody, 50 micromoles, 1.0 mL) in DMSO was added and the reoxidation mixture was allowed to react for 2 hours at room temperature (or until full reoxidation of the cysteine thiols to reform the inter-chain cysteine disulfides is observed by UHPLC) with gentle (<150 rpm) shaking at an antibody concentration of 2-3 mg/mL. The reoxidation mixture was then sterile-filtered and diluted in a conjugation buffer containing PBS and 1 mM EDTA to a final antibody concentration of ˜1.5 mg/mL. Compound 40 was added as a DMSO solution (10 molar equivalent/antibody, 1 micromole, in 0.9 mL DMSO) to 9 mL of this reoxidised antibody solution (15 mg, 100 nanomoles). The solution was mixed for 1.25 hours at room temperature, after which the conjugation reaction was quenched by addition of N-acetyl cysteine (4 micromoles, 40 μL at 100 mM) and diluted to >50 mL in PBS. The conjugation mixture was purified by spin filtration using a 15 mL Amicon Ultracell 50 kDa MWCO spin filter, sterile-filtered, analysed and stored at +4° C. The reduction and reoxidation steps are monitored by comparison of the relative amounts of individual light and heavy chains with full length antibody as observed by UHPLC analysis on a Shimadzu Prominence system using a PhenomenexAeris 3.6u XB-C18 150×2.1 mm column eluting with a gradient of water and acetonitrile. UHPLC analysis on a Shimadzu Prominence system using a PhenomenexAeris3.6u XB-C18 150×2.1 mm column eluting with a gradient of water and acetonitrile on a reduced sample of conjugate trastuzumab-B at 280 nm and 330 nm (Compound 40 specific) shows unconjugated light chains and a mixture of unconjugated heavy chains and heavy chains attached to a single molecule of Compound 40, consistent with a drug-per-antibody ratio (DAR) of 1.68 molecules of Compound 40 per antibody.

UHPLC analysis on a Shimadzu Prominence system using a Tosoh Bioscience TSKgel SuperSW mAb HTP 4 μm 4.6×150 mm column (with a 4 μm 3.0×20 mm guard column) eluting with 0.3 mL/minute sterile-filtered SEC buffer containing 200 mM potassium phosphate pH 6.95, 250 mM potassium chloride and 10% isopropanol (v/v) on a sample of conjugate trastuzumab-40 at 280 nm shows a monomer purity of 93% with no impurity detected. UHPLC SEC analysis gives a concentration of final conjugate trastuzumab-B at 0.74 mg/mL in 17 mL, obtained mass of conjugate trastuzumab-40 is 12.5 mg (83% yield).

A 50 mM solution of tris(2-carboxyethyl)phosphine hydrochloride (TCEP) in phosphate-buffered saline pH 7.4 (PBS) was added (42 molar equivalent/antibody, 56 micromoles, 1.12 mL at 50 mM) to a 14.09 mL solution of antibody (200 mg, 1.33 micromoles) in reduction buffer containing PBS and 1 mM ethylenediaminetetraacetic acid (EDTA) and a final antibody concentration of 4.0 mg/mL. The reduction mixture was heated at +25° C. for 24 hours (or until full reduction observed by UHPLC) in an incubator with gentle (<100 rpm) shaking. After cooling down to room temperature, the reduced antibody was buffer exchanged, via Tangential Flow Filtration unit (TFF) using mPES, MidiKros® 30 kDa fiber filter with 115 cm2surface area, into a reoxidation buffer containing PBS pH 7.4 and 1 mM EDTA to remove all the excess reducing agent. The reduced antibody was centrifuged for 3 min at 4000 rpm and then filtered using 0.45 μM membrane filter. A 50 mM solution of dehydroascorbic acid (DHAA, 15 molar equivalent/antibody, 20 micromoles, 400 μL at 50 mM) in DMSO was added and the reoxidation mixture was allowed to react for 16 hours at room temperature with gentle (<100 rpm) shaking at an antibody concentration of 2.5 mg/mL (or until full reoxidation of the cysteine thiols to reform the inter-chain cysteine disulfides is observed by UHPLC). The reoxidation mixture was centrifuged for 3 min at 4000 rpm and then sterile-filtered using 0.2 μM membrane filter. Compound 23 was added as a DMSO solution (10 molar equivalent/antibody, 13.3 micromoles, in 6.6 mL DMSO) to 80 mL of this reoxidised antibody solution (200 mg, 1.33 micromoles) for a 10% (v/v) final DMSO concentration. The solution was shaken for 3 hours at +25° C. and then the conjugation was quenched with N-acetyl cysteine (72.3 micromoles, 0.72 mL at 100 mM).

Excess free drug was removed via Tangential Flow Filtration unit (TFF) using mPES, MidiKros® 30 kDa fiber filter with 115 cm2surface area, into buffer containing PBS pH 7.4. Extent of free drug removal was monitored by UHPLC-RP using neat conjugate. After complete removal of free drug, ADC were formulated onto 25 mM Histidine, 200 mM Sucrose, pH 6.0, via TFF using mPES, MidiKros® 30 kDa fiber filter with 115 cm2surface area. The whole process of R347 conjugation with Compound 23 was repeated with 400 mg antibody and also purified using TFF. ADC from both batches were combined and then filtered using Mustang filter under sterile atmosphere and then further stored at −78° C.

UHPLC analysis on a Shimadzu Prominence system using a PhenomenexAeris3.6u XB-C18 150×2.1 mm column eluting with a gradient of water and acetonitrile on a reduced sample of Conjugate at 214 nm and 330 nm (Compound 23 specific) shows a mixture of light and heavy chains attached to several molecules of Compound 23, consistent with a drug-per-antibody ratio (DAR) of 1.71 molecules of Compound 23 per antibody.

UHPLC analysis on a Shimadzu Prominence system using a Tosoh Bioscience TSKgel SuperSW mAb HTP 4 μm 4.6×150 mm column (with a 4 μm 3.0×20 mm guard column) eluting with 0.3 mL/minute sterile-filtered SEC buffer containing 200 mM potassium phosphate pH 6.95, 250 mM potassium chloride and 10% isopropanol (v/v) on a sample of ADC at 280 nm shows a monomer purity of greater than 97%. UHPLC SEC analysis gives a concentration of final ADC at 1.92 mg/mL in 265 mL, obtained mass of ADC is 509 mg (85% yield).

A 50 mM solution of tris(2-carboxyethyl)phosphine hydrochloride (TCEP) in phosphate-buffered saline pH 7.4 (PBS) was added (50 molar equivalent/antibody, 20 micromoles, 0.4 mL) to a 13.25 mL solution of antibody (60 mg, 0.4 micromoles) in reduction buffer containing PBS and 1 mM ethylenediaminetetraacetic acid (EDTA) at a final antibody concentration of 4.5 mg/mL. The reduction mixture was heated at +37° C. for 3 hours (or until full reduction is observed by UHPLC) in an incubator with gentle (<150 rpm) shaking. After cooling down to room temperature, the reduced antibody was buffer exchanged, via spin filter centrifugation, into a reoxidation buffer containing PBS and 1 mM EDTA to remove excess reducing agent. A 50 mM solution of dehydroascorbic acid (DHAA, 12 molar equivalent/antibody, 4.8 micromoles, 96 μL) in DMSO was added and the reoxidation mixture was allowed to react for 17 hours at room temperature (or until full reoxidation of the cysteine thiols to reform the inter-chain cysteine disulfides is observed by UHPLC) with gentle (<150 rpm) shaking at an antibody concentration of ˜1.6 mg/mL. The reoxidation mixture was then sterile-filtered and diluted in a conjugation buffer containing PBS and 1 mM EDTA to a final antibody concentration of ˜1.5 mg/mL. Compound 40 was added as a DMSO solution (11 molar equivalent/antibody, 0.44 micromoles, in 0.45 mL DMSO) to 4.05 mL of this reoxidised antibody solution (6 mg, 40 nanomoles). The solution was mixed for 1.25 hours at room temperature, after which the conjugation reaction was quenched by addition of N-acetyl cysteine (1.76 micromoles, 17.6 μL at 100 mM). The conjugation mixture was purified by spin filtration with PBS using a 15 mL Amicon Ultracell 50 kDa MWCO spin filter, sterile-filtered, analysed and stored at +4° C.

The reduction and reoxidation steps are monitored by comparison of the relative amounts of individual light and heavy chains with full length antibody as observed by UHPLC analysis on a Shimadzu Prominence system using a PhenomenexAeris 3.6u XB-C18 150×2.1 mm column eluting with a gradient of water and acetonitrile. UHPLC analysis on a Shimadzu Prominence system using a Phenomenex Aeris 3.6u XB-C18 150×2.1 mm column eluting with a gradient of water and acetonitrile on a reduced sample of Conjugate R347-40 at 280 nm and 330 nm (Conjugate 40 specific) shows unconjugated light chains and a mixture of unconjugated heavy chains and heavy chains attached to a single molecule of Compound 40, consistent with a drug-per-antibody ratio (DAR) of 1.86 molecules of Compound 40 per antibody.

UHPLC analysis on a Shimadzu Prominence system using a Tosoh Bioscience TSKgel G3000SWXL 5 μm 7.8×300 mm column (with a 7 μm 6.0×40 mm guard column) eluting with sterile-filtered SEC buffer containing 200 mM potassium phosphate pH 6.95, 250 mM potassium chloride and 10% isopropanol (v/v) on a sample of Conjugate R347-40 at 280 nm shows a monomer purity of 97% with no impurity detected. UHPLC SEC analysis gives a concentration of final Conjugate R347-40 at 0.87 mg/mL in 5.5 mL, obtained mass of Conjugate R347-40 is 4.8 mg (80% yield).

A 50 mM solution of DTT (Dithiothreitol) in phosphate-buffered saline pH 7.4 (PBS) was added (40 molar equivalent/antibody, 40 micromoles, 825 μL) to a 37.5 mL solution of antibody HLL2 (150 mg, 1 micromol) in reduction buffer containing PBS and 1 mM ethylenediaminetetraacetic acid (EDTA) and a final antibody concentration of 4 mg/mL. The reduction mixture was incubated at room temperature overnight with gentle (135 rpm) shaking. The reduced antibody was buffer-exchanged against PBS+1 mM EDTA (to remove the excess of DTT) using TFF (TangentialFlowFiltration, Spectrum Labs 115 cm2hollow fibre cassette with 50 kDa molecular weight cut off). The sample was filtered using a 0.4 μm syringe filter to remove any debris from the TFF step and antibody concentration brought to 1.5 mg/mL before reoxidation. A 50 mM solution of dehydroascorbic acid (DHAA, 15 molar equivalent/antibody, 13.9 micromoles, 0.28 mL) in DMSO was added and the reoxidation mixture was allowed to react for 16 hours at room temperature under gentle (<150 rpm) shaking. The reoxidation mixture was then sterile-filtered; 139 mg of antibody (92.6 mL as 1.5 mg/mL solution) was obtained, 14 mL of which was taken forward for conjugation with Compound 23 (estimated ca. 21 mg antibody, 0.14 micromoles). Compound 23 was added as a DMSO solution (10 molar equivalent/antibody, 0.33 micromoles in 0.133 mL DMSO) to 14 mL of the reoxidised antibody solution. The conjugation mixture was topped with 1.27 ml of DMSO to bring the final DMSO concentration to 10% (v/v) and incubated for 3 hours at room temperature under gentle agitation (135 rpm). Free drug was then removed from the antibody-drug conjugate by extensive diafiltration in PBS using a spin filter device (Amicon Ultra-30K centrifugal filter, Millipore). The resulting conjugation mixture was sterile-filtered and analysed by UHPLC.

UHPLC analysis on a Shimadzu Prominence system using a Phenomenex Aeris 3.6u XB-C18 150×2.1 mm column eluting with a gradient of water and acetonitrile on a reduced sample of Conjugate at 214 nm (ADC) and 330 nm (Compound 23 specific) shows a mixture of heavy chains either unconjugated or attached to 1 molecule of Compound 23, consistent with a drug-per-antibody ratio (DAR) of 1.64 molecules of Compound 23 per antibody.

UHPLC analysis on a Shimadzu Prominence system using a Tosoh Bioscience TSKgel SuperSW mAb HTP 4 μm 4.6×150 mm column (with a 4 μm 3.0×20 mm guard column) eluting with 0.3 mL/minute sterile-filtered SEC buffer containing 200 mM potassium phosphate pH 6.95, 250 mM potassium chloride and 10% isopropanol (v/v) on a sample of ADC at 280 nm shows a monomer purity greater than 97%. UHPLC SEC analysis gives a concentration of final ADC at 2.06 mg/mL in 10 mL, obtained mass of ADC is 20.6 mg.

A 50 mM solution of DL-dithiothreitol (DTT) in phosphate-buffered saline pH 7.4 (PBS) was added (80 molar equivalent/antibody, 53.3 micromoles, 1.07 mL) to a 25 mL solution of antibody CD79b (100 mg, 667 nmol) in reduction buffer containing PBS and 1 mM ethylenediaminetetraacetic acid (EDTA) and a final antibody concentration of 4 mg/mL.

The reduction mixture was allowed to react at room temperature overnight with gentle shaking. The reduced antibody was buffer exchanged, via spin filter centrifugation, into a reoxidation buffer containing PBS and 1 mM EDTA to remove all the excess reducing agent. A 50 mM solution of dehydroascorbic acid (DHAA, 15 molar equivalent/antibody, 9.28 micromoles, 185 μL) in DMSO was added and the reoxidation mixture was allowed to react for 16 hours at room temperature under gentle (<150 rpm) shaking. The reoxidation mixture was then sterile-filtered; Compound 23 was added as a DMSO solution (15 molar equivalent/antibody, 1.8 micromoles in 1.0 mL DMSO) to 9 mL of this reoxidised antibody solution (18 mg, 120 nanomoles) for a 10% (v/v) final DMSO concentration and a final antibody concentration of 1.8 mg/mL in PBS+1 mM EDTA. The solution was mixed for 2 hours at room temperature under gentle agitation (135 rpm), then the conjugation was quenched by addition of N-acetyl cysteine (7.2 micromoles, 72 μL at 100 mM), then purified by spin filtration using a 15 mL Amicon Ultracell 50 kDa MWCO spin filter, sterile-filtered and analysed.

UHPLC analysis on a Shimadzu Prominence system using a Phenomenex Aeris 3.6u XB-C18 150×2.1 mm column eluting with a gradient of water and acetonitrile on a reduced sample of Conjugate at 280 nm (ADC) and 330 nm (Compound 23 specific) unconjugated light chains and a mixture of unconjugated heavy chains and heavy chains attached to 1 or 2 molecules of Compound 23, consistent with a drug-per-antibody ratio (DAR) of 2.08 molecules of Compound 23 per antibody.

UHPLC analysis on a Shimadzu Prominence system using a Tosoh Bioscience TSKgel SuperSW mAb HTP 4 μm 4.6×150 mm column (with a 4 μm 3.0×20 mm guard column) eluting with 0.3 mL/minute sterile-filtered SEC buffer containing 200 mM potassium phosphate pH 6.95, 250 mM potassium chloride and 10% isopropanol (v/v) on a sample of ADC at 280 nm shows a monomer purity of greater than 98%. UHPLC SEC analysis gives a concentration of final ADC at 1.62 mg/mL in 7.6 mL, obtained mass of ADC is 12.28 mg.

Example 5—In Vitro Testing

Medium from sub-confluent (80-90% confluency) cell culture in a T75 flask was aspirated and the flask rinsed with PBS (about 20 ml) and emptied. Trypsin-EDTA (5 ml) was added, the flask returned to the 37° C. gassed incubator for up to about 5 minutes, then rapped sharply to dislodge and dissociate cells from the plastic. The cell suspension was transferred to a sterile 50 ml screw-top centrifuge tube, diluted with growth medium to a final volume of 15 ml, then centrifuged (400 g for 5 min). The supernatant was aspirated and the pellet re-suspended in 10 ml culture medium. Repeated pipetting may be necessary to produce monodisperse cell suspensions. The cell concentration and viability are measured of trypan blue cell stained cells, using a haemocytometer. Cells were diluted to 2×105/ml, dispensed (50 μl/well) into 96 well flat bottom plates and incubated overnight before use.

A stock solution (1 ml) of antibody drug conjugate (ADC) (20 μg/ml) was made by dilution of filter-sterilised ADC into cell culture medium. A set of 8×10-fold dilutions of stock ADC were made in a 24 well plate by serial transfer of 100 μl onto 900 μl of cell culture medium.

ADC dilution was dispensed (50 μl/well) into 4 replicate wells of the 96-well plate, containing 50 μl cell suspension seeded the previous day. Control wells received 50 μl cell culture medium.

The 96-well plate containing cells and ADCs was incubated at 37° C. in a CO2-gassed incubator for the exposure time.

At the end of the incubation period, cell viability was measured by MTS assay. MTS (Promega) was dispensed (20 μl per well) into each well and incubated for 4 hours at 37° C. in the CO2-gassed incubator. Well absorbance was measured at 490 nm. Percentage cell survival was calculated from the mean absorbance in the 4 ADC-treated wells compared to the mean absorbance in the 4 control untreated wells (100%). IC50was determined from the doses-response data using GraphPad Prism using the non-linear curve fit algorithm: sigmoidal, 4PL X is log(concentration).

Testing of AntiCD79b-23

The concentration and viability of cells from a sub-confluent (80-90% confluency) T75 flask are measured by trypan blue staining, and counted using the LUNA-II™ Automated Cell Counter. Cells were diluted to 2×105/ml, dispensed (50 μl/well) into 96-well flat-bottom plates.

A stock solution (1 ml) of antibody drug conjugate (ADC) (20 μg/ml) was made by dilution of filter-sterilised ADC into cell culture medium. A set of 8×10-fold dilutions of stock ADC were made in a 24-well plate by serial transfer of 100 μl into 900 μl of cell culture medium. ADC dilution was dispensed (50 μl/well) into 4 replicate wells of the 96-well plate, containing 50 μl cell suspension seeded the previously. Control wells received 50 μl cell culture medium. The 96-well plate containing cells and ADCs was incubated at 37° C. in a CO2-gassed incubator for the exposure time.

At the end of the incubation period, cell viability was measured by MTS assay. MTS (Promega) was dispensed (20 μl per well) into each well and incubated for 4 hours at 37° C. in the CO2-gassed incubator. Well absorbance was measured at 490 nm. Percentage cell survival was calculated from the mean absorbance in the 4 ADC-treated wells compared to the mean absorbance in the 4 control untreated wells (100%). IC50was determined from the dose-response data using GraphPad Prism using the non-linear curve fit algorithm: sigmoidal dose-response curve with variable slope.

Female severe combined immune-deficient mice (Fox Chase SCID®, C.B-17/Icr-Prkdcscid, Charles River) were ten weeks old with a body weight (BW) range of 16.2 to 21.9 grams on Day 1 of the study. The animals were fed ad libitum water (reverse osmosis, 1 ppm Cl), and NIH 31 Modified and Irradiated Lab Diet® consisting of 18.0% crude protein, 5.0% crude fat, and 5.0% crude fibre. The mice were housed on irradiated Enricho'cobs™ Laboratory Animal Bedding in static micro-isolators on a 12-hour light cycle at 20-22° C. (68-72° F.) and 40-60% humidity. CR Discovery Services specifically complies with the recommendations of the Guide for Care and Use of Laboratory Animals with respect to restraint, husbandry, surgical procedures, feed and fluid regulation, and veterinary care. The animal care and use program at CR Discovery Services is accredited by the Association for Assessment and Accreditation of Laboratory Animal Care International (AAALAC), which assures compliance with accepted standards for the care and use of laboratory animals.

In Vivo Implantation and Tumour Growth

Xenografts were initiated with BT474 human breast carcinomas maintained at CR Discovery Services by serial subcutaneous transplantation into the SCID mice (see above). On the day of tumour implant, each test mouse received a 1-mm3BT474 fragment implanted subcutaneously in the right flank, and tumour growth was monitored as the average size approached the target range of 100 to 150 mm3. Thirty-three days after tumour implantation, designated as Day 1 of the study, the animals were sorted into nine groups each consisting of ten mice with individual tumour volumes of 75 to 144 mm3and group mean tumour volumes of 111 to 112 mm3. Tumours were measured in two dimensions using calipers, and volume was calculated using the formula:
Tumour Volume (mm3)=0.5(w2×l)
where w=width and l=length, in mm, of the tumour. Tumour weight may be estimated with the assumption that 1 mg is equivalent to 1 mm3of tumour volume.

Treatment began on Day 1 in groups of mice (n=10) with established subcutaneous BT474 tumors (75-196 mm3). Trastuzumab-23 was administered intravenously once on Day 1 (qd×1) at two dosages (0.3 and 1 mg/kg). A vehicle-treated group served as the control group for efficacy analysis. Tumors were measured twice per week until the study was ended on Day 60. Each mouse was euthanized when its tumor reached the endpoint volume of 800 mm3or on the final day, whichever came first. The time to endpoint (TTE) was calculated for each mouse.

Treatment outcome was determined from percent tumor growth delay (% TGD), defined as the percent increase in median TTE for treated versus control mice, with differences between groups deemed statistically significant at P≤0.05 using logrank survival analysis. Mice were monitored for complete regression (CR) and partial regression (PR) responses.

Treatment tolerability was assessed by body weight measurements and frequent observation for signs of treatment-related side effects. Treatment tolerability was assessed by body weight measurements and frequent observation for signs of treatment-related side effects. All regimens were acceptably tolerated.

The median TTE for vehicle-treated controls was 44.4 days, establishing a maximum possible TGD of 15.6 days (35%) for the 60-day study. ADC regimens resulted in the maximum possible TGD, produced survival benefit that was statistically significantly different from vehicle-treated controls (P<0.01) and could not be distinguished based on logrank analysis (P>0.05). Differences within ADC treatments were only evident in the MTV on the final day and numbers and types of regression responses produced by each regimen.

Trastuzumab-23 at 1 mg/kg produced four partial regressions (PRs). The results are illustrated inFIG.1.

Treatment began on Day 1 in groups of mice (n=9 or 10) with established subcutaneous BT474 tumors (108-196 mm3). Trastuzumab-40 was administered intravenously once on Day 1 (qd×1) at two dosages (0.3 and 1 mg/kg). A vehicle-treated group served as the control group for efficacy analysis. Tumors were measured twice per week until the study was ended on Day 62. Each mouse was euthanized when its tumor reached the endpoint volume of 1000 mm3or on the final day, whichever came first. The time to endpoint (TTE) was calculated for each mouse.

Treatment outcome was determined from percent tumor growth delay (% TGD), defined as the percent increase in median TTE for treated versus control mice, with differences between groups deemed statistically significant at P≤0.05 using logrank survival analysis. Mice were monitored for complete regression (CR) and partial regression (PR) responses.

Treatment tolerability was assessed by body weight measurements and frequent observation for signs of treatment-related side effects. Treatment tolerability was assessed by body weight measurements and frequent observation for signs of treatment-related side effects.

All regimens were acceptably tolerated. The median TTE for vehicle-treated controls was 52.9 days, establishing a maximum possible TGD of 9.1 days (17%) for the 62-day study. ADC treatment resulted in the maximum possible TGD, however only the 1 mg/kg treatment produced survival benefit that was statistically significantly different from vehicle-treated controls (P<0.001).

Trastuzumab-40, at 1 mg/kg produced four partial regressions (PRs) and one complete regression (CR) which remained a tumour-free survivor (TFS) at study end. The results are shown inFIG.2.

Tumor Cell Culture

Human NCI-N87 gastric carcinoma lymphoma cells were cultured in RPMI-1640 medium supplemented with 10% fetal bovine serum, 2 mM glutamine, 100 units/mL penicillin, 100 μg/mL streptomycin sulfate and 25 μg/mL gentamicin. The cells were grown in tissue culture flasks in a humidified incubator at 37° C., in an atmosphere of 5% CO2and 95% air.

In Vivo Implantation and Tumor Growth

The NCI-N87 cells used for implantation were harvested during log phase growth and resuspended in phosphate buffered saline (PBS) containing 50% Matrigel™ (BD Biosciences). On the day of tumor implant, each test mouse (SCID mice as in Example 6) was injected subcutaneously in the right flank with 1×107cells (0.1 mL cell suspension), and tumor growth was monitored as the average size approached the target range of 100 to 150 mm3. Eleven days later, designated as Day 1 of the study, mice were sorted according to calculated tumor size into eleven groups each consisting of ten animals with individual tumor volumes ranging from 88 to 144 mm3and group mean tumor volumes of 119-121 mm3. Tumors were measured in two dimensions using calipers, and volume was calculated using the formula:
Tumour Volume (mm3)=0.5(w2×l)
where w=width and l=length, in mm, of the tumour. Tumour weight may be estimated with the assumption that 1 mg is equivalent to 1 mm3of tumour volume

Treatment began on Day 1 in groups of mice (n=10) with established subcutaneous NCI-N87 tumors (88-144 mm3). Trastuzumab-23 was administered intravenously once on Day 1 (qd×1) at two dosages (0.3 and 1 mg/kg). A vehicle-treated group served as the control group for efficacy analysis. Tumors were measured twice per week until the study was ended on Day 81. Each mouse was euthanized when its tumor reached the endpoint volume of 800 mm3or on the final day, whichever came first. The time to endpoint (TTE) was calculated for each mouse.

Treatment outcome was determined from percent tumor growth delay (% TGD), defined as the percent increase in median TTE for treated versus control mice, with differences between groups deemed statistically significant at P≤0.05 using logrank survival analysis. Mice were monitored for complete regression (CR) and partial regression (PR) responses.

Treatment tolerability was assessed by body weight measurements and frequent observation for signs of treatment-related side effects. Treatment tolerability was assessed by body weight measurements and frequent observation for signs of treatment-related side effects. All regimens were acceptably tolerated.

The median TTE for vehicle-treated controls was 53.4 days, establishing a maximum possible TGD of 27.6 days (52%) for the 81-day study. Trastuzumab-23 tested at 1 mg/kg produced survival benefit that was statistically significantly different from vehicle-treated controls (P<0.001) and resulted in the maximum possible TGD. At 0.3 mg/kg, the median TTE was 80.5 days, which corresponds to TGD of 27.1 days (51%).

Trastuzumab-23, at 1 mg/kg produced one partial regressions (PR). The results are illustrated inFIG.3.

Treatment began on Day 1 in groups of mice (n=10) with established subcutaneous NCI-N87 tumors (75-126 mm3). Trastuzumab-40 was administered intravenously once on Day 1 (qd×1) at two dosages (0.3 and 1 mg/kg). A vehicle-treated group served as the control group for efficacy analysis. Tumors were measured twice per week until the study was ended on Day 83. Each mouse was euthanized when its tumor reached the endpoint volume of 800 mm3or on the final day, whichever came first. The time to endpoint (TTE) was calculated for each mouse.

Treatment outcome was determined from percent tumor growth delay (% TGD), defined as the percent increase in median TTE for treated versus control mice, with differences between groups deemed statistically significant at P≤0.05 using logrank survival analysis. Mice were monitored for complete regression (CR) and partial regression (PR) responses. Treatment tolerability was assessed by body weight measurements and frequent observation for signs of treatment-related side effects. Treatment tolerability was assessed by body weight measurements and frequent observation for signs of treatment-related side effects. All regimens were acceptably tolerated.

The median TTE for vehicle-treated controls was 44.9 days, establishing a maximum possible TGD of 38.1 days (85%) for the 83-day study. Trastuzumab-40 (0.3 mg/kg) had a median TTE of 54.2 days corresponding to a TGD of 9.3 days (21%). Trastuzumab-40 (1 mg/kg) had a median TTE of 61.6 days corresponding to a TGD of 16.7 days (37%).

The results are illustrated inFIG.4.

A single dose toxicity study was used to determine the maximum tolerated dose (MTD) and safety profile of Trastuzumab-23. Male Sprague Dawley rats (Harlan, Inc) were dosed once by slow bolus intravenous injection via the tail vein with vehicle control (25 mM Histidine-HCl, 7% sucrose, 0.02% Polysorbate 80, pH 6.0) or test material (Trastuzumab-23).

Parameters evaluated during the study included mortality, physical examinations, cageside observations, body weights, body weight changes, clinical pathology (clinical chemistry, hematology, and coagulation), and gross pathology findings. All animals were terminated on Study Day (SD) 29.

Tolerability was determined based on toxicity end points, including body weight loss (>10%) and bone marrow suppression. Based on minimal adverse findings at the high dose, the maximum tolerated dose (MTD) in the rat after a single dose of Trastuzumab-23 was determined to be >7 mg/kg, which was the highest dose level evaluated.

Therapeutic Index

The Therapeutic Index can be calculated by dividing the maximum tolerated single dose (MTD) of non-targeted ADC in rat, by the minimal effective single dose (MED) of the a targeted ADC. The MED is the single dose necessary to achieve tumour stasis in an in vivo model at 28 days (for NCI-N87 xenograft).

Thus for conjugates of compound 23, the therapeutic index is the MTD of greater than 7 mg/kg divided by the MED which is less than 1 mg/kg (seeFIG.3at 28 days), giving a Therapeutic Index of greater than 7.

A Single-Dose Toxicity study was performed in male Cynomolgus macaques monkeys (Macaca fascicularis) of Cambodian origin following a single intravenous (IV) bolus injection of ADC-SG3400. The study was conducted in 2 phases. In phase 1, animals (n=1) were treated at dose levels of 1, 3, or 6 mg/kg to determine the optimal dose level to explore in phase 2. Animals were dosed by slow bolus intravenous injection via the saphenous vein with vehicle control (25 mM Histidine, 200 mM Sucrose, pH 6.0) or test material (Trastuzumab-23). Based on observations of significant body weight loss at 6 mg/kg, a dose level of 4.5 mg/kg was chosen for phase 2 of the study. In phase 2, animals (n=3) were administered a single dose of 4.5 mg/kg Trastuzumab-23 on Day 1 and necropsied on Days 71 or 72.

Tolerability was determined based on toxicity end points, including body weight loss (>10%) and bone marrow suppression. There was no unscheduled mortality in any animal administered Trastuzumab-23. The major findings were body weight loss and bone marrow suppression at the highest tested dose of 6 mg/kg. Based on these data, and minimal signs of toxicity at next lowest dose, the MTD of Trastuzumab-23 in cynos was 4.5 mg/kg.

All documents and other references mentioned above are herein incorporated by reference.