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Nature Chemical Biology Sep 2017Yatakemycin (YTM) is an extraordinarily toxic DNA alkylating agent with potent antimicrobial and antitumor properties and is the most recent addition to the CC-1065 and...
Yatakemycin (YTM) is an extraordinarily toxic DNA alkylating agent with potent antimicrobial and antitumor properties and is the most recent addition to the CC-1065 and duocarmycin family of natural products. Though bulky DNA lesions the size of those produced by YTM are normally removed from the genome by the nucleotide-excision repair (NER) pathway, YTM adducts are also a substrate for the bacterial DNA glycosylases AlkD and YtkR2, unexpectedly implicating base-excision repair (BER) in their elimination. The reason for the extreme toxicity of these lesions and the molecular basis for the way they are eliminated by BER have been unclear. Here, we describe the structural and biochemical properties of YTM adducts that are responsible for their toxicity, and define the mechanism by which they are excised by AlkD. These findings delineate an alternative strategy for repair of bulky DNA damage and establish the cellular utility of this pathway relative to that of NER.
Topics: Biological Products; DNA Adducts; DNA Damage; DNA Repair; Drug Resistance, Bacterial; Duocarmycins; Indoles; Molecular Structure; Pyrroles
PubMed: 28759018
DOI: 10.1038/nchembio.2439 -
Clinical Cancer Research : An Official... Oct 2017Carcinosarcomas (CS) are highly aggressive gynecologic malignancies containing both carcinomatous and sarcomatous elements with heterogeneous HER2/neu expression. We...
Carcinosarcomas (CS) are highly aggressive gynecologic malignancies containing both carcinomatous and sarcomatous elements with heterogeneous HER2/neu expression. We compared the efficacy of SYD985 (Synthon Biopharmaceuticals BV), a novel HER2-targeting antibody-drug conjugate (ADC), to trastuzumab emtansine (T-DM1, Genentech-Roche) against primary uterine and ovarian CS. Eight primary CS cell lines were evaluated for HER2/neu surface expression by IHC and gene amplification by FISH assays. The experiments included cytotoxicity, antibody-dependent cellular cytotoxicity (ADCC), proliferation, viability, and bystander killing. activity was studied in mouse xenograft and patient-derived xenograft (PDX) models. SYD985 and T-DM1 induced similar levels of ADCC against CS cell lines with low and high HER2/neu expression when challanged in the presence of effector cells. In contrast, SYD985 was 7- to 54-fold more potent than T-DM1 in the absence of effector cells. SYD985, unlike T-DM1, was active against CS demonstrating low or heterogeneous HER2/neu expression. Specifically, the mean IC values were 0.060 μg/mL and 3.221 μg/mL ( < 0.0001) against HER2/neu 0/1+ cell lines and 0.013 μg/mL and 0.096 μg/mL ( < 0.0001) against HER2/neu 3+ cell lines for SYD985 versus T-DM1, respectively. Importantly, unlike T-DM1, SYD985 induced efficient bystander killing of HER2/neu 0/1+ tumor cells admixed with HER2/neu 3+ cells. studies confirmed that SYD985 is more active than T-DM1 in CS and highly effective against HER2/neu expressing xenografts and PDX. SYD985 may represent a novel and highly effective ADC against HER2-expressing CS. Clinical studies with SYD985 in patients harboring chemotherapy-resistant CS with low/moderate and high HER2 expression are warranted. .
Topics: Ado-Trastuzumab Emtansine; Animals; Antibody-Dependent Cell Cytotoxicity; Carcinosarcoma; Cell Line, Tumor; Cell Proliferation; Duocarmycins; Female; Gene Expression Regulation, Neoplastic; Humans; Immunoconjugates; Indoles; Maytansine; Mice; Ovarian Neoplasms; Pyrrolidinones; Receptor, ErbB-2; Trastuzumab; Uterine Neoplasms; Xenograft Model Antitumor Assays
PubMed: 28679774
DOI: 10.1158/1078-0432.CCR-16-2862 -
Gynecologic Oncology Jul 2017Epithelial ovarian cancer (EOC) is an aggressive and heterogeneous disease. <10% of EOC demonstrate HER2/neu 3+ receptor over-expression. However, moderate to low (i.e.,...
BACKGROUND
Epithelial ovarian cancer (EOC) is an aggressive and heterogeneous disease. <10% of EOC demonstrate HER2/neu 3+ receptor over-expression. However, moderate to low (i.e., 2+ and 1+) HER2/neu expression is reported in up to 50% of EOC. The objective of this study was to compare the anti-tumor activity of SYD985, a novel HER2-targeting antibody-drug conjugate (ADC), to trastuzumab emtansine (T-DM1) in EOC models with differential HER2/neu expression.
METHODS
The cytotoxicity of SYD985 and T-DM1 was evaluated using ten primary EOC cell lines with 0/1+, 2+, and 3+ HER2/neu expression in antibody-dependent cellular cytotoxicity (ADCC), proliferation, viability and bystander killing experiments. Finally, the in vivo activity of SYD985 and T-DM1 was also studied in ovarian cancer xenografts.
RESULTS
SYD985 and T-DM1 induced similar ADCC in the presence of peripheral blood lymphocytes (PBL) against EOC cell lines with differential HER2/neu expression. In contrast, SYD985 was 3 to 42 fold more cytotoxic in the absence of PBL when compared to T-DM1 (p<0.0001). Unlike T-DM1, SYD985 induced efficient bystander killing of HER2/neu 0/1+ tumor cells when admixed with HER2/neu 3+ EOC cells. In vivo studies confirmed that SYD985 is significantly more active than T-DM1 against HER2/neu 3+ EOC xenografts.
CONCLUSIONS
SYD985 is a novel ADC with remarkable activity against EOC with strong (3+) as well as moderate to low (i.e., 2+ and 1+) HER2/neu expression. SYD985 is more potent than T-DM1 in comparative experiments and unlike T-DM1, it is active against EOC demonstrating moderate/low or heterogeneous HER2/neu expression.
Topics: Ado-Trastuzumab Emtansine; Adult; Aged; Animals; Antibodies, Monoclonal, Humanized; Antibody-Dependent Cell Cytotoxicity; Antineoplastic Agents, Alkylating; Bystander Effect; Carcinoma, Ovarian Epithelial; Cell Line, Tumor; Duocarmycins; Female; Humans; Immunotoxins; Indoles; Maytansine; Mice; Mice, SCID; Middle Aged; Neoplasms, Glandular and Epithelial; Ovarian Neoplasms; Pyrrolidinones; Random Allocation; Receptor, ErbB-2; Trastuzumab; Xenograft Model Antitumor Assays
PubMed: 28473206
DOI: 10.1016/j.ygyno.2017.04.023 -
ACS Central Science Apr 2017Near-IR photocaging groups based on the heptamethine cyanine scaffold present the opportunity to visualize and then treat diseased tissue with potent bioactive...
Near-IR photocaging groups based on the heptamethine cyanine scaffold present the opportunity to visualize and then treat diseased tissue with potent bioactive molecules. Here we describe fundamental chemical studies that enable biological validation of this approach. Guided by rational design, including computational analysis, we characterize the impact of structural alterations on the cyanine uncaging reaction. A modest change to the ethylenediamine linker (,'-dimethyl to ,'-diethyl) leads to a bathochromic shift in the absorbance maxima, while decreasing background hydrolysis. Building on these structure-function relationship studies, we prepare antibody conjugates that uncage a derivative of duocarmycin, a potent cytotoxic natural product. The optimal conjugate, CyEt-Pan-Duo, undergoes small molecule release with 780 nm light, exhibits activity in the picomolar range, and demonstrates excellent light-to-dark selectivity. Mouse xenograft studies illustrate that the construct can be imaged prior to uncaging with an external laser source. Significant reduction in tumor burden is observed following a single dose of conjugate and near-IR light. These studies define key chemical principles that enable the identification of cyanine-based photocages with enhanced properties for drug delivery.
PubMed: 28470051
DOI: 10.1021/acscentsci.7b00026 -
MAbs 2017The currently marketed antibody-drug conjugates (ADC) destabilize microtubule assembly in cancer cells and initiate apoptosis in patients. However, few tumor antigens...
The currently marketed antibody-drug conjugates (ADC) destabilize microtubule assembly in cancer cells and initiate apoptosis in patients. However, few tumor antigens (TA) are expressed at high densities on cancer lesions, potentially minimizing the therapeutic index of current ADC regimens. The peptide/human leukocyte antigen (HLA) complex can be specifically targeted by therapeutic antibodies (designated T cell receptor [TCR]-like antibodies) and adequately distinguish malignant cells, but has not been the focus of ADC development. We analyzed the killing potential of TCR-like ADCs when cross-linked to the DNA alkylating compound duocarmycin. Our data comprise proof-of-principle results that TCR-like ADCs mediate potent tumor cytotoxicity, particularly under common scenarios of low TA/HLA density, and support their continued development alongside agents that disrupt DNA replication. Additionally, TCR-like antibody ligand binding appears to play an important role in ADC functionality and should be addressed during therapy development to avoid binding patterns that negate ADC killing efficacy.
Topics: Animals; Antibodies, Neoplasm; Cell Line, Tumor; Drug Delivery Systems; Duocarmycins; HLA Antigens; Humans; Indoles; Mice; Neoplasms; Peptides; Pyrrolidinones; Receptors, Antigen, T-Cell
PubMed: 28273004
DOI: 10.1080/19420862.2017.1302630 -
Journal of Medicinal Chemistry Dec 2016Here we describe a new approach for tumor targeting in which augmented concentrations of Fe(II) in cancer cells and/or the tumor microenvironment triggers drug release...
Here we describe a new approach for tumor targeting in which augmented concentrations of Fe(II) in cancer cells and/or the tumor microenvironment triggers drug release from an Fe(II)-reactive prodrug conjugate. The 1,2,4-trioxolane scaffold developed to enable this approach can in principle be applied to a broad range of cancer therapeutics and is illustrated here with Fe(II)-targeted forms of a microtubule toxin and a duocarmycin-class DNA-alkylating agent. We show that the intrinsic reactivity/toxicity of the duocarmycin analog is masked in the conjugated form and this greatly reduced toxicity in mice. This in turn permitted elevated dosing levels, leading to higher systemic exposure and a significantly improved response in tumor xenograft models. Overall our results suggest that Fe(II)-dependent drug delivery via trioxolane conjugates could have significant utility in expanding the therapeutic index of a range of clinical and preclinical stage cancer chemotherapeutics.
Topics: Animals; Antineoplastic Agents; Cell Proliferation; Cell Survival; Dose-Response Relationship, Drug; Drug Delivery Systems; Drug Screening Assays, Antitumor; Duocarmycins; Female; Ferrous Compounds; Humans; Indoles; Mammary Neoplasms, Experimental; Mice; Mice, Inbred NOD; Mice, Nude; Mice, SCID; Molecular Structure; Prodrugs; Pyrroles; Structure-Activity Relationship; Tumor Cells, Cultured
PubMed: 27936709
DOI: 10.1021/acs.jmedchem.6b01470 -
Angewandte Chemie (International Ed. in... Jan 2017The cleavage of a protecting group from a protein or drug under bioorthogonal conditions enables accurate spatiotemporal control over protein or drug activity. Disclosed...
The cleavage of a protecting group from a protein or drug under bioorthogonal conditions enables accurate spatiotemporal control over protein or drug activity. Disclosed herein is that vinyl ethers serve as protecting groups for alcohol-containing molecules and as reagents for bioorthogonal bond-cleavage reactions. A vinyl ether moiety was installed in a range of molecules, including amino acids, a monosaccharide, a fluorophore, and an analogue of the cytotoxic drug duocarmycin. Tetrazine-mediated decaging proceeded under biocompatible conditions with good yields and reasonable kinetics. Importantly, the nontoxic, vinyl ether duocarmycin double prodrug was successfully decaged in live cells to reinstate cytotoxicity. This bioorthogonal reaction presents broad applicability and may be suitable for in vivo applications.
Topics: Alcohols; Cell Line, Tumor; Cycloaddition Reaction; Electrons; Hep G2 Cells; Humans; Kinetics; Molecular Structure; Quantum Theory; Tetrazoles; Vinyl Compounds
PubMed: 27930843
DOI: 10.1002/anie.201609607 -
Bioorganic & Medicinal Chemistry Oct 2016The design, synthesis, and evaluation of methyl 1,2,8,8a-tetrahydrocyclopropa[c]imidazolo[4,5-e]indol-4-one-6-carboxylate (CImI) derivatives are detailed representing...
Synthesis and evaluation of duocarmycin SA analogs incorporating the methyl 1,2,8,8a-tetrahydrocyclopropa[c]imidazolo[4,5-e]indol-4-one-6-carboxylate (CImI) alkylation subunit.
The design, synthesis, and evaluation of methyl 1,2,8,8a-tetrahydrocyclopropa[c]imidazolo[4,5-e]indol-4-one-6-carboxylate (CImI) derivatives are detailed representing analogs of duocarmycin SA and yatakemycin containing an imidazole replacement for the fused pyrrole found in the DNA alkylation subunit.
Topics: Animals; Cell Line, Tumor; Cell Proliferation; Duocarmycins; Imidazoles; Indoles; Mice; Molecular Structure; Pyrroles; Stereoisomerism
PubMed: 27221071
DOI: 10.1016/j.bmc.2016.04.050 -
Chemistry (Weinheim An Der Bergstrasse,... Jun 2016To evaluate the reactivity of antitumor agents in a nucleosome architecture, we conducted in vitro studies to assess the alkylation level of duocarmycin B2 on...
To evaluate the reactivity of antitumor agents in a nucleosome architecture, we conducted in vitro studies to assess the alkylation level of duocarmycin B2 on nucleosomes with core and linker DNA using sequencing gel electrophoresis. Our results suggested that the alkylating efficiencies of duocarmycin B2 were significantly decreased in core DNA and increased at the histone-free linker DNA sites when compared with naked DNA conditions. Our finding that nucleosome assembly alters the accessibility of duocarmycin B2 to duplex DNA could advance its design as an antitumor agent.
Topics: Alkylation; Antineoplastic Agents; Base Sequence; DNA; Duocarmycins; Indoles; Nucleosomes; Pyrrolidinones
PubMed: 27123891
DOI: 10.1002/chem.201600950 -
Nature Nov 2015Threats to genomic integrity arising from DNA damage are mitigated by DNA glycosylases, which initiate the base excision repair pathway by locating and excising aberrant...
Threats to genomic integrity arising from DNA damage are mitigated by DNA glycosylases, which initiate the base excision repair pathway by locating and excising aberrant nucleobases. How these enzymes find small modifications within the genome is a current area of intensive research. A hallmark of these and other DNA repair enzymes is their use of base flipping to sequester modified nucleotides from the DNA helix and into an active site pocket. Consequently, base flipping is generally regarded as an essential aspect of lesion recognition and a necessary precursor to base excision. Here we present the first, to our knowledge, DNA glycosylase mechanism that does not require base flipping for either binding or catalysis. Using the DNA glycosylase AlkD from Bacillus cereus, we crystallographically monitored excision of an alkylpurine substrate as a function of time, and reconstructed the steps along the reaction coordinate through structures representing substrate, intermediate and product complexes. Instead of directly interacting with the damaged nucleobase, AlkD recognizes aberrant base pairs through interactions with the phosphoribose backbone, while the lesion remains stacked in the DNA duplex. Quantum mechanical calculations revealed that these contacts include catalytic charge-dipole and CH-π interactions that preferentially stabilize the transition state. We show in vitro and in vivo how this unique means of recognition and catalysis enables AlkD to repair large adducts formed by yatakemycin, a member of the duocarmycin family of antimicrobial natural products exploited in bacterial warfare and chemotherapeutic trials. Bulky adducts of this or any type are not excised by DNA glycosylases that use a traditional base-flipping mechanism. Hence, these findings represent a new model for DNA repair and provide insights into catalysis of base excision.
Topics: Bacillus cereus; Base Pairing; Biocatalysis; Catalytic Domain; Crystallography, X-Ray; DNA Adducts; DNA Damage; DNA Glycosylases; DNA Repair; Duocarmycins; Indoles; Models, Molecular; Pyrroles
PubMed: 26524531
DOI: 10.1038/nature15728