Publications by authors named "John A Hartley"

150 Publications

Prognostic Threshold for Circulating Tumor Cells in Patients With Pancreatic and Midgut Neuroendocrine Tumors.

J Clin Endocrinol Metab 2021 Mar;106(3):872-882

Department of Oncology, UCL Cancer Institute, University College London, London, UK.

Background: Circulating tumor cells (CTCs) are detectable in patients with neuroendocrine tumors (NETs) and are accurate prognostic markers although the optimum threshold has not been defined.

Objective: This work aims to define optimal prognostic CTC thresholds in PanNET and midgut NETs.

Patients And Methods: CellSearch was used to enumerate CTCs in 199 patients with metastatic pancreatic (PanNET) (90) or midgut NETs (109). Patients were followed for progression-free survival (PFS) and overall survival (OS) for a minimum of 3 years or until death.

Results: The area under the receiver operating characteristic curve (AUROC) for progression at 12 months in PanNETs and midgut NETs identified the optimal CTC threshold as 1 or greater and 2 or greater, respectively. In multivariate logistic regression analysis, these thresholds were predictive for 12-month progression with an odds ratio (OR) of 6.69 (P < .01) for PanNETs and 5.88 (P < .003) for midgut NETs. The same thresholds were found to be optimal for predicting death at 36 months, with an OR of 2.87 (P < .03) and 5.09 (P < .005) for PanNETs and midgut NETs, respectively. In multivariate Cox hazard regression analysis for PFS in PanNETs, 1 or greater CTC had a hazard ratio (HR) of 2.6 (P < .01), whereas 2 or greater CTCs had an HR of 2.25 (P < .01) in midgut NETs. In multivariate analysis OS in PanNETs, 1 or greater CTCs had an HR of 3.16 (P < .01) and in midgut NETs, 2 or greater CTCs had an HR of 1.73 (P < .06).

Conclusions: The optimal CTC threshold to predict PFS and OS in metastatic PanNETs and midgut NETs is 1 and 2, respectively. These thresholds can be used to stratify patients in clinical practice and clinical trials.
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http://dx.doi.org/10.1210/clinem/dgaa822DOI Listing
March 2021

The Role of Specific ATP-Binding Cassette Transporters in the Acquired Resistance to Pyrrolobenzodiazepine Dimer-Containing Antibody-Drug Conjugates.

Mol Cancer Ther 2020 09 15;19(9):1856-1865. Epub 2020 Jul 15.

Cancer Research UK Drug-DNA Interactions Research Group, UCL Cancer Institute, London, United Kingdom.

Antibody-drug conjugates (ADC) containing pyrrolobenzodiazepine (PBD) dimers are being evaluated clinically in both hematologic and solid tumors. These include ADCT-301 (camidanlumab tesirine) and ADCT-402 (loncastuximab tesirine) in pivotal phase II trials that contain the payload tesirine, which releases the PBD dimer warhead SG3199. An important consideration in future clinical development is acquired resistance. The aim was to generate and characterize PBD acquired resistant cell lines in both hematologic and solid tumor settings. Human Karpas-299 (ALCL) and NCI-N87 (gastric cancer) cells were incubated with increasing IC doses of ADC (targeting CD25 and HER2, respectively) or SG3199 in a pulsed manner until stable acquired resistance was established. The level of resistance achieved was approximately 3,000-fold for ADCT-301 and 3-fold for SG3199 in Karpas-299, and 8-fold for ADCT-502 and 4-fold for SG3199 in NCI-N87. Cross-resistance between ADC and SG3199, and with an alternative PBD-containing ADC or PBD dimer was observed. The acquired resistant lines produced fewer DNA interstrand cross-links, indicating an upstream mechanism of resistance. Loss of antibody binding or internalization was not observed. A human drug transporter PCR Array revealed several genes upregulated in all the resistant cell lines, including and , but not (). These findings were confirmed by RT-PCR and Western blot, and inhibitors and siRNA knockdown of and recovered drug sensitivity. These data show that acquired resistance to PBD-ADCs and SG3199 can involve specific ATP-binding cassette drug transporters. This has clinical implications as potential biomarkers of resistance and for the rational design of drug combinations.
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http://dx.doi.org/10.1158/1535-7163.MCT-20-0222DOI Listing
September 2020

Antibody-drug conjugates (ADCs) delivering pyrrolobenzodiazepine (PBD) dimers for cancer therapy.

Authors:
John A Hartley

Expert Opin Biol Ther 2020 Jun 16:1-13. Epub 2020 Jun 16.

Professor of Cancer Studies, UCL Cancer Institute , London, UK.

Introduction: The rationally designed pyrrolobenzodiazepine (PBD) dimers emerged around ten years ago as a new class of drug component for antibody-drug conjugates (ADC). They produce highly cytotoxic DNA cross-links, exploiting a completely different cellular target to the auristatin and maytansinoid tubulin inhibitor classes and a different mode of DNA damage to other DNA interacting warheads such as calicheamicin.

Areas Covered: The properties which make the PBD dimers suitable warheads for ADCs, and the development of the two main payload structures talirine and tesirine, are discussed. The clinical experience with the twenty PBD dimer-containing ADCs to enter the clinic is reviewed, with a focus on vadastuximab talirine and rovalpituzumab tesirine, both of which were discontinued following pivotal studies, and loncastuximab tesirine and camidanlumab tesirine which are progressing towards approval.

Expert Opinion: Reviewing the clinical efficacy and safety data from almost forty clinical trials of PBD dimer-containing ADCs highlights the complexities and challenges of ADC early clinical development. It enables some conclusions to be made about reasons for failure and suggests strategies to optimise the future clinical development of this promising class of ADCs in a rapidly expanding field.
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http://dx.doi.org/10.1080/14712598.2020.1776255DOI Listing
June 2020

Integrin αvβ6-specific therapy for pancreatic cancer developed from foot-and-mouth-disease virus.

Theranostics 2020 12;10(7):2930-2942. Epub 2020 Feb 12.

Barts Cancer Institute, Queen Mary University of London, John Vane Science Centre, Charterhouse Square, London EC1M 6BQ, UK.

: The 5-year survival rate for pancreatic ductal adenocarcinoma (PDAC) has remained at <5% for decades because no effective therapies have been identified. Integrin αvβ6 is overexpressed in most PDAC and represents a promising therapeutic target. Thus, we attempted to develop an αvβ6-specific peptide-drug conjugate (PDC) for therapy of PDAC. : We conjugated the DNA-binding pyrrolobenzodiazepine (PBD)-based payload SG3249 (tesirine) to an αvβ6-specific 20mer peptide from the VP1 coat protein of foot-and-mouth-disease virus (FMDV) (forming conjugate SG3299) or to a non-targeting peptide (forming conjugate SG3511). PDCs were tested for specificity and toxicity on αvβ6-negative versus-positive PDAC cells, patient-derived cell lines from tumor xenografts, and on two different models of PDAC. Immunohistochemical analyses were performed to establish therapeutic mechanism. : The αvβ6-targeted PDC SG3299 was significantly more toxic (up to 78-fold) for αvβ6-expressing versus αvβ6-negative PDAC cell lines , and achieved significantly higher toxicity at equal dose than the non-targeted PDC SG3511 (up to 15-fold better). Moreover, SG3299 eliminated established (100mm) Capan-1 PDAC human xenografts, extending the lifespan of mice significantly (P=0.005). Immunohistochemistry revealed SG3299 induced DNA damage and apoptosis (increased γH2AX and cleaved caspase 3, respectively) associated with significant reductions in proliferation (Ki67), β6 expression and PDAC tumour growth. : The FMDV-peptide drug conjugate SG3299 showed αvβ6-selectivity and and can specifically eliminate αvβ6-positive cancers, providing a promising new molecular- specific therapy for pancreatic cancer.
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http://dx.doi.org/10.7150/thno.38702DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7053198PMC
March 2021

Targeting of EGFR by a combination of antibodies mediates unconventional EGFR trafficking and degradation.

Sci Rep 2020 01 20;10(1):663. Epub 2020 Jan 20.

Cancer Research UK Drug-DNA Interactions Research Group, UCL Cancer Institute, Paul O'Gorman Building, University College London, London, WC1E 6DD, UK.

Antibody combinations targeting cell surface receptors are a new modality of cancer therapy. The trafficking and signalling mechanisms regulated by such therapeutics are not fully understood but could underlie differential tumour responses. We explored EGFR trafficking upon treatment with the antibody combination Sym004 which has shown promise clinically. Sym004 promoted EGFR endocytosis distinctly from EGF: it was asynchronous, not accompanied by canonical signalling events and involved EGFR clustering within detergent-insoluble plasma mebrane-associated tubules. Sym004 induced lysosomal degradation independently of EGFR ubiquitylation but dependent upon Hrs/Tsg101 that are required for the formation of intraluminal vesicles (ILVs) within late endosomes. We propose Sym004 cross-links EGFR physically triggering EGFR endocytosis and incorporation onto ILVs and so Sym004 sensitivity correlates with EGFR numbers available for binding, rather than specific signalling events. Consistently Sym004 efficacy and potentiation of cisplatin responses correlated with EGFR surface expression in head and neck cancer cells. These findings will have implications in understanding the mode of action of this new class of cancer therapeutics.
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http://dx.doi.org/10.1038/s41598-019-57153-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6970994PMC
January 2020

TR1801-ADC: a highly potent cMet antibody-drug conjugate with high activity in patient-derived xenograft models of solid tumors.

Mol Oncol 2020 01 3;14(1):54-68. Epub 2019 Dec 3.

Tanabe Research Laboratories U.S.A., Inc., San Diego, CA, USA.

cMet is a well-characterized oncogene that is the target of many drugs including small molecule and biologic pathway inhibitors, and, more recently, antibody-drug conjugates (ADCs). However, the clinical benefit from cMet-targeted therapy has been limited. We developed a novel cMet-targeted 'third-generation' ADC, TR1801-ADC, that was optimized at different levels including specificity, stability, toxin-linker, conjugation site, and in vivo efficacy. Our nonagonistic cMet antibody was site-specifically conjugated to the pyrrolobenzodiazepine (PBD) toxin-linker tesirine and has picomolar activity in cancer cell lines derived from different solid tumors including lung, colorectal, and gastric cancers. The potency of our cMet ADC is independent of MET gene copy number, and its antitumor activity was high not only in high cMet-expressing cell lines but also in medium-to-low cMet cell lines (40 000-90 000 cMet/cell) in which a cMet ADC with tubulin inhibitor payload was considerably less potent. In vivo xenografts with low-medium cMet expression were also very responsive to TR1801-ADC at a single dose, while a cMet ADC using a tubulin inhibitor showed a substantially reduced efficacy. Furthermore, TR1801-ADC had excellent efficacy with significant antitumor activity in 90% of tested patient-derived xenograft models of gastric, colorectal, and head and neck cancers: 7 of 10 gastric models, 4 of 10 colorectal cancer models, and 3 of 10 head and neck cancer models showed complete tumor regression after a single-dose administration. Altogether, TR1801-ADC is a new generation cMet ADC with best-in-class preclinical efficacy and good tolerability in rats.
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http://dx.doi.org/10.1002/1878-0261.12600DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6944112PMC
January 2020

VEROnA Protocol: A Pilot, Open-Label, Single-Arm, Phase 0, Window-of-Opportunity Study of Vandetanib-Eluting Radiopaque Embolic Beads (BTG-002814) in Patients With Resectable Liver Malignancies.

JMIR Res Protoc 2019 Oct 2;8(10):e13696. Epub 2019 Oct 2.

National Institute for Health Research University College London Hospitals Biomedical Centre, University College London Cancer Institute, London, United Kingdom.

Background: Transarterial chemoembolization (TACE) is the current standard of care for patients with intermediate-stage hepatocellular carcinoma (HCC) and is also a treatment option for patients with liver metastases from colorectal cancer. However, TACE is not a curative treatment, and tumor progression occurs in more than half of the patients treated. Despite advances and technical refinements of TACE, including the introduction of drug-eluting beads-TACE, the clinical efficacy of TACE has not been optimized, and improved arterial therapies are required.

Objective: The primary objectives of the VEROnA study are to evaluate the safety and tolerability of vandetanib-eluting radiopaque embolic beads (BTG-002814) in patients with resectable liver malignancies and to determine concentrations of vandetanib and the N-desmethyl metabolite in plasma and resected liver following treatment with BTG-002814.

Methods: The VEROnA study is a first-in-human, open-label, single-arm, phase 0, window-of-opportunity study of BTG-002814 (containing 100 mg vandetanib) delivered transarterially, 7 to 21 days before surgery in patients with resectable liver malignancies. Eligible patients have a diagnosis of colorectal liver metastases, or HCC (Childs Pugh A), diagnosed histologically or radiologically, and are candidates for liver surgery. All patients are followed up for 28 days following surgery. Secondary objectives of this study are to evaluate the anatomical distribution of BTG-002814 on noncontrast-enhanced imaging, to evaluate histopathological features in the surgical specimen, and to assess changes in blood flow on dynamic contrast-enhanced magnetic resonance imaging following treatment with BTG-002814. Exploratory objectives of this study are to study blood biomarkers with the potential to identify patients likely to respond to treatment and to correlate the distribution of BTG-002814 on imaging with pathology by 3-dimensional modeling.

Results: Enrollment for the study was completed in February 2019. Results of a planned interim analysis were reviewed by a safety committee after the first 3 patients completed follow-up. The recommendation of the committee was to continue the study without any changes to the dose or trial design, as there were no significant unexpected toxicities related to BTG-002814.

Conclusions: The VEROnA study is studying the feasibility of administering BTG-002814 to optimize the use of this novel technology as liver-directed therapy for patients with primary and secondary liver cancer.

Trial Registration: ClinicalTrial.gov NCT03291379; https://clinicaltrials.gov/ct2/show/NCT03291379.

International Registered Report Identifier (irrid): DERR1-10.2196/13696.
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http://dx.doi.org/10.2196/13696DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6777276PMC
October 2019

Synthesis and evaluation of pyrrolobenzodiazepine dimer antibody-drug conjugates with dual β-glucuronide and dipeptide triggers.

Eur J Med Chem 2019 Oct 18;179:591-607. Epub 2019 Jun 18.

Spirogen, QMB Innovation Centre, 42 New Road, London, E1 2AX, United Kingdom.

Antibody-drug conjugates (ADCs) containing pyrrolobenzodiazepine (PBD) dimers are currently being evaluated in human oncology clinical trials with encouraging results. To further improve the therapeutic window, next-generation PBD drug-linker design has focused on the inclusion of additional tumor-selective triggers and use of lower-potency PBDs. β-Glucuronidase is a well-known target for discovery prodrugs due to increased presence in tumor cells and microenvironment. In this study, a β-glucuronidase cleavable cap was investigated at the PBD N10-position and compared with corresponding free imine ADCs. SG3600 (glucuronide) ADCs showed in vitro and in vivo efficacy/tolerability comparable to SG3400 (imine) ADCs, and good 50% inhibitory concentration differentials were observed in vitro between control non-antigen-targeted ADCs and targeted ADCs. Dependence on β-glucuronidase for SG3600 activity was demonstrated through CRISPRCas9 knockdown studies and addition of exogenous β-glucuronidase. SG3600 showed better serum stability, improved conjugation efficiency and was able to reach high drug-to-antibody ratio without aggregation.
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http://dx.doi.org/10.1016/j.ejmech.2019.06.044DOI Listing
October 2019

Potentiation of PBD Dimers by Lipophilicity Manipulation.

Curr Top Med Chem 2019 ;19(9):741-752

Spirogen-Medimmune, Queen Mary BioEnterprises Innovation Centre, 42 New road, Whitechapel, London E1 2AX, United Kingdom.

Background & Introduction: Pyrrolobenzodiazepine (PBD) dimers are highly potent DNA cross-linking agents used as warheads in Antibody Drug Conjugates (ADCs) for cancer therapy. We propose to investigate the correlation existing between the lipophilicity of those molecules and their activity (both in vitro and in vivo) as well as any effect observed during conjugation.

Materials And Methods: Reaction progress was monitored by Thin-Layer Chromatography (TLC) using Merck Kieselgel 60 F254 silica gel, with a 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.

Results: We have successfully designed and synthesized a novel PBD warhead (SG3312) with enhanced physicochemical properties. The warhead also displayed increased potency in vitro. After overcoming some epimerization issues, the synthesis of enantiomerically pure payload was achieved (SG3259) and fulfilled our criteria for a simplified and more efficient conjugation. No addition of propylene glycol was required, and high DAR and excellent monomeric purity were achieved.

Conclusion: The ADC (Herceptin-maia-SG3259) has been shown to release the active warhead (SG3312) upon exposure to Cathepsin B and demonstrated encouraging activity both in vitro and in vivo.
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http://dx.doi.org/10.2174/1568026619666190401112517DOI Listing
July 2019

Circulating tumour cells and their association with bone metastases in patients with neuroendocrine tumours.

Br J Cancer 2019 02 14;120(3):294-300. Epub 2019 Jan 14.

Department of Oncology, UCL Cancer Institute, University College London, London, UK.

Background: Bone metastases are associated with a worse outcome in patients with neuroendocrine tumours (NETs). Tumour overexpression of C-X-C chemokine receptor 4 (CXCR4) appears predictive of skeletal involvement. We investigated the role of circulating tumour cells (CTCs) and CXCR4 expression on CTCs as potential predictors of skeleton invasion.

Methods: Blood from patients with metastatic bronchial, midgut or pancreatic NET (pNET) was analysed by CellSearch. CXCR4 immunohistochemistry was performed on matched formalin-fixed paraffin-embedded (FFPE) samples.

Results: Two hundred and fifty-four patients were recruited with 121 midgut and 119 pNETs, of which 51 and 36% had detectable CTCs, respectively. Bone metastases were reported in 30% of midgut and 23% of pNET patients and were significantly associated with CTC presence (p = 0.003 and p < 0.0001). In a subgroup of 40 patients, 85% patients with CTCs had CTCs positive for CXCR4 expression. The proportion of CXCR4-positive CTCs in patients with bone metastases was 56% compared to 35% in those without (p = 0.18) it. Staining for CXCR4 on matched FFPE tissue showed a trend towards a correlation with CXCR4 expression on CTCs (p = 0.08).

Conclusions: CTC presence is associated with bone metastases in NETs. CXCR4 may be involved in CTC osteotropism and present a therapeutic target to reduce skeletal morbidity.
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http://dx.doi.org/10.1038/s41416-018-0367-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6353867PMC
February 2019

Antitumor Activity of MEDI3726 (ADCT-401), a Pyrrolobenzodiazepine Antibody-Drug Conjugate Targeting PSMA, in Preclinical Models of Prostate Cancer.

Mol Cancer Ther 2018 10 31;17(10):2176-2186. Epub 2018 Jul 31.

ADC Therapeutics (UK) Limited, London, United Kingdom.

Prostate-specific membrane antigen (PSMA) is a membrane-bound glutamate carboxypeptidase that is highly expressed in nearly all prostate cancers with the highest expression in metastatic castration-resistant prostate cancer (mCRPC). The prevalence of increased surface expression and constitutive internalization of PSMA make it an attractive target for an antibody-drug conjugate (ADC) approach to treating patients with mCRPC. MEDI3726 (previously known as ADCT-401) is an ADC consisting of an engineered version of the anti-PSMA antibody J591 site specifically conjugated to the pyrrolobenzodiazepine (PBD) dimer tesirine. MEDI3726 specifically binds the extracellular domain of PSMA and, once internalized, releases the PBD dimer to crosslink DNA and trigger cell death. , MEDI3726 demonstrated potent and specific cytotoxicity in a panel of PSMA-positive prostate cancer cell lines, consistent with internalization and DNA interstrand crosslinking. , MEDI3726 showed robust antitumor activity against the LNCaP and the castration-resistant CWR22Rv1 prostate cancer cell line xenografts. MEDI3726 also demonstrated durable antitumor activity in the PSMA-positive human prostate cancer patient-derived xenograft (PDX) LuCaP models. This activity correlated with increased phosphorylated Histone H2AX in tumor xenografts treated with MEDI3726. MEDI3726 is being evaluated in a phase I clinical trial as a treatment for patients with metastatic castrate-resistant prostate cancer (NCT02991911). .
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http://dx.doi.org/10.1158/1535-7163.MCT-17-0982DOI Listing
October 2018

Pre-clinical pharmacology and mechanism of action of SG3199, the pyrrolobenzodiazepine (PBD) dimer warhead component of antibody-drug conjugate (ADC) payload tesirine.

Sci Rep 2018 Jul 11;8(1):10479. Epub 2018 Jul 11.

Spirogen Ltd, QMB Innovation Centre, 42 New Road, London, E1 2AX, UK.

Synthetic pyrrolobenzodiazepine (PBD) dimers, where two PBD monomers are linked through their aromatic A-ring phenolic C8-positions via a flexible propyldioxy tether, are highly efficient DNA minor groove cross-linking agents with potent cytotoxicity. PBD dimer SG3199 is the released warhead component of the antibody-drug conjugate (ADC) payload tesirine (SG3249), currently being evaluated in several ADC clinical trials. SG3199 was potently cytotoxic against a panel of human solid tumour and haematological cancer cell lines with a mean GI of 151.5 pM. Cells defective in DNA repair protein ERCC1 or homologous recombination repair showed increased sensitivity to SG3199 and the drug was only moderately susceptible to multidrug resistance mechanisms. SG3199 was highly efficient at producing DNA interstrand cross-links in naked linear plasmid DNA and dose-dependent cross-linking was observed in cells. Cross-links formed rapidly in cells and persisted over 36 hours. Following intravenous (iv) administration to rats SG3199 showed a very rapid clearance with a half life as short as 8 minutes. These combined properties of cytotoxic potency, rapid formation and persistence of DNA interstrand cross-links and very short half-life contribute to the emerging success of SG3199 as a warhead in clinical stage ADCs.
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http://dx.doi.org/10.1038/s41598-018-28533-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6041317PMC
July 2018

DNA-Binding Properties of New Fluorescent AzaHx Amides: Methoxypyridylazabenzimidazolepyrroleimidazole/pyrrole.

Chembiochem 2018 09 15;19(18):1979-1987. Epub 2018 Aug 15.

Department of Chemistry, Georgia State University, 50 Decatur Street SE, Atlanta, GA, 30303, USA.

DNA minor groove binding polyamides have been extensively developed to control abnormal gene expression. The establishment of novel, inherently fluorescent 2-(p-anisyl)benzimidazole (Hx) amides has provided an alternative path for studying DNA binding in cells by direct observation of cell localization. Because of the 2:1 antiparallel stacking homodimer binding mode of these molecules to DNA, modification of Hx amides to 2-(p-anisyl)-4-azabenzimidazole (AzaHx) amides has successfully extended the DNA-recognition repertoire from central CG [recognized by Hx-I (I=N-methylimidazole)] to central GC [recognized by AzaHx-P (P=N-methylpyrrole)] recognition. For potential targeting of two consecutive GG bases, modification of the AzaHx moiety to 2- and 3-pyridyl-aza-benzimidazole (Pyr-AzaHx) moieties was explored. The newly designed molecules are also small-sized, fluorescent amides with the Pyr-AzaHx moiety connected to two conventional five-membered heterocycles. Complementary biophysical methods were performed to investigate the DNA-binding properties of these molecules. The results showed that neither 3-Pyr-AzaHx nor 2-Pyr-AzaHx was able to mimic I-I=N-methylimidazole-N-methylimidazole to target GG dinucleotides specifically. Rather, 3-Pyr-AzaHx was found to function like AzaHx, f-I (f=formamide), or P-I as an antiparallel stacked dimer. 3-Pyr-AzaHx-PI (2) binds 5'-ACGCGT'-3' with improved binding affinity and high sequence specificity in comparison to its parent molecule AzaHx-PI (1). However, 2-Pyr-AzaHx is detrimental to DNA binding because of an unfavorable steric clash upon stacking in the minor groove.
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http://dx.doi.org/10.1002/cbic.201800273DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6398938PMC
September 2018

Design, synthesis, nuclear localization, and biological activity of a fluorescent duocarmycin analog, HxTfA.

Bioorg Med Chem Lett 2018 05 5;28(8):1342-1347. Epub 2018 Mar 5.

Department of Chemistry, Hope College, Holland, MI 49423, United States.

HxTfA 4 is a fluorescent analog of a potent cytotoxic and antimalarial agent, TfA 3, which is currently being investigated for the development of an antimalarial vaccine, PlasProtect®. HxTfA contains a p-anisylbenzimidazole or Hx moiety, which is endowed with a blue emission upon excitation at 318 nm; thus enabling it to be used as a surrogate for probing the cellular fate of TfA using confocal microscopy, and addressing the question of nuclear localization. HxTfA exhibits similar selectivity to TfA for A-tract sequences of DNA, alkylating adenine-N3, albeit at 10-fold higher concentrations. It also possesses in vitro cytotoxicity against A549 human lung carcinoma cells and Plasmodium falciparum. Confocal microscopy studies showed for the first time that HxTfA, and by inference TfA, entered A549 cells and localized in the nucleus to exert its biological activity. At biologically relevant concentrations, HxTfA elicits DNA damage response as evidenced by a marked increase in the levels of γH2AX observed by confocal microscopy and immunoblotting studies, and ultimately induces apoptosis.
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http://dx.doi.org/10.1016/j.bmcl.2018.03.016DOI Listing
May 2018

MEK inhibition leads to BRCA2 downregulation and sensitization to DNA damaging agents in pancreas and ovarian cancer models.

Oncotarget 2018 Feb 22;9(14):11592-11603. Epub 2018 Jan 22.

Cancer Research UK Drug-DNA Interactions Research Group, UCL Cancer Institute, Paul O'Gorman Building, University College London, London WC1E 6DD, UK.

Targeting the DNA damage response (DDR) in tumors with defective DNA repair is a clinically successful strategy. The RAS/RAF/MEK/ERK signalling pathway is frequently deregulated in human cancers. In this study, we explored the effects of MEK inhibition on the homologous recombination pathway and explored the potential for combination therapy of MEK inhibitors with DDR inhibitors and a hypoxia-activated prodrug. We studied effects of combining pimasertib, a selective allosteric inhibitor of MEK1/2, with olaparib, a small molecule inhibitor of poly (adenosine diphosphate [ADP]-ribose) polymerases (PARP), and with the hypoxia-activated prodrug evofosfamide in ovarian and pancreatic cancer cell lines. Apoptosis was assessed by Caspase 3/7 assay and protein expression was detected by immunoblotting. DNA damage response was monitored with γH2AX and RAD51 immunofluorescence staining. antitumor activity of pimasertib with evofosfamide were assessed in pancreatic cancer xenografts. We found that BRCA2 protein expression was downregulated following pimasertib treatment under hypoxic conditions. This translated into reduced homologous recombination repair demonstrated by levels of RAD51 foci. MEK inhibition was sufficient to induce formation of γH2AX foci, suggesting that inhibition of this pathway would impair DNA repair. When combined with olaparib or evofosfamide, pimasertib treatment enhanced DNA damage and increased apoptosis. The combination of pimasertib with evofosfamide demonstrated increased anti-tumor activity in BRCA wild-type Mia-PaCa-2 xenograft model, but not in the BRCA mutated BxPC3 model. Our data suggest that targeted MEK inhibition leads to impaired homologous recombination DNA damage repair and increased PARP inhibition sensitivity in BRCA-2 proficient cancers.
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http://dx.doi.org/10.18632/oncotarget.24294DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5837749PMC
February 2018

ADCT-402, a PBD dimer-containing antibody drug conjugate targeting CD19-expressing malignancies.

Blood 2018 03 3;131(10):1094-1105. Epub 2018 Jan 3.

ADC Therapeutics (UK) Limited, London, United Kingdom.

Human CD19 antigen is a 95-kDa type I membrane glycoprotein in the immunoglobulin superfamily whose expression is limited to the various stages of B-cell development and differentiation and is maintained in the majority of B-cell malignancies, including leukemias and non-Hodgkin lymphomas of B-cell origin. Coupled with its differential and favorable expression profile, CD19 has rapid internalization kinetics and is not shed into the circulation, making it an ideal target for the development of antibody-drug conjugates (ADCs) to treat B-cell malignancies. ADCT-402 (loncastuximab tesirine) is a novel CD19-targeted ADC delivering SG3199, a highly cytotoxic DNA minor groove interstrand crosslinking pyrrolobenzodiazepine (PDB) dimer warhead. It showed potent and highly targeted in vitro cytotoxicity in CD19-expressing human cell lines. ADCT-402 was specifically bound, internalized, and trafficked to lysosomes in CD19-expressing cells and, following release of the PBD warhead, resulted in formation of DNA crosslinks that persisted for 36 hours. Bystander killing of CD19 cells by ADCT-402 was also observed. In vivo, single doses of ADCT-402 resulted in highly potent, dose-dependent antitumor activity in several subcutaneous and disseminated human tumor models with marked superiority to comparator ADCs delivering tubulin inhibitors. Dose-dependent DNA crosslinks and γ-H2AX DNA damage response were measured in tumors by 24 hours after single dose administration, whereas matched peripheral blood mononuclear cells showed no evidence of DNA damage. Pharmacokinetic analysis in rat and cynomolgus monkey showed excellent stability and tolerability of ADCT-402 in vivo. Together, these impressive data were used to support the clinical testing of this novel ADC in patients with CD19-expressing B-cell malignancies.
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http://dx.doi.org/10.1182/blood-2017-10-813493DOI Listing
March 2018

Corrigendum: Phylogenetic ctDNA analysis depicts early-stage lung cancer evolution.

Authors:
Christopher Abbosh Nicolai J Birkbak Gareth A Wilson Mariam Jamal-Hanjani Tudor Constantin Raheleh Salari John Le Quesne David A Moore Selvaraju Veeriah Rachel Rosenthal Teresa Marafioti Eser Kirkizlar Thomas B K Watkins Nicholas McGranahan Sophia Ward Luke Martinson Joan Riley Francesco Fraioli Maise Al Bakir Eva Grönroos Francisco Zambrana Raymondo Endozo Wenya Linda Bi Fiona M Fennessy Nicole Sponer Diana Johnson Joanne Laycock Seema Shafi Justyna Czyzewska-Khan Andrew Rowan Tim Chambers Nik Matthews Samra Turajlic Crispin Hiley Siow Ming Lee Martin D Forster Tanya Ahmad Mary Falzon Elaine Borg David Lawrence Martin Hayward Shyam Kolvekar Nikolaos Panagiotopoulos Sam M Janes Ricky Thakrar Asia Ahmed Fiona Blackhall Yvonne Summers Dina Hafez Ashwini Naik Apratim Ganguly Stephanie Kareht Rajesh Shah Leena Joseph Anne Marie Quinn Phil A Crosbie Babu Naidu Gary Middleton Gerald Langman Simon Trotter Marianne Nicolson Hardy Remmen Keith Kerr Mahendran Chetty Lesley Gomersall Dean A Fennell Apostolos Nakas Sridhar Rathinam Girija Anand Sajid Khan Peter Russell Veni Ezhil Babikir Ismail Melanie Irvin-Sellers Vineet Prakash Jason F Lester Malgorzata Kornaszewska Richard Attanoos Haydn Adams Helen Davies Dahmane Oukrif Ayse U Akarca John A Hartley Helen L Lowe Sara Lock Natasha Iles Harriet Bell Yenting Ngai Greg Elgar Zoltan Szallasi Roland F Schwarz Javier Herrero Aengus Stewart Sergio A Quezada Karl S Peggs Peter Van Loo Caroline Dive C Jimmy Lin Matthew Rabinowitz Hugo J W L Aerts Allan Hackshaw Jacqui A Shaw Bernhard G Zimmermann Charles Swanton

Nature 2018 02 20;554(7691):264. Epub 2017 Dec 20.

This corrects the article DOI: 10.1038/nature22364.
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http://dx.doi.org/10.1038/nature25161DOI Listing
February 2018

The emerging role of anti-CD25 directed therapies as both immune modulators and targeted agents in cancer.

Br J Haematol 2017 10 30;179(1):20-35. Epub 2017 May 30.

UCL Cancer Institute, London, UK.

CD25 (also termed IL2RA) forms one component of the high-affinity heterotrimeric interleukin 2 (IL2) receptor on activated T cells. Its affinity for IL2 and cellular function are tightly regulated and vary in different cell types. The high frequency of CD25 on the surface of many different haematological tumour cells is now well established and, apart from its prognostic significance, CD25 may be present on leukaemic stem cells and enable oncogenic signalling pathways in leukaemic cells. Additionally, high CD25 expression in activated circulating immune cells and Tregs is a factor that has already been exploited by IL2 immunotherapies for treatment of tumours and autoimmune disease. The relative clinical safety and efficacy of administering anti-CD25 radioimmunoconjugates and immunotoxins in various haematological tumour indications has been established and clinical trials of a novel CD25-directed antibody drug conjugate are underway.
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http://dx.doi.org/10.1111/bjh.14770DOI Listing
October 2017

Phylogenetic ctDNA analysis depicts early-stage lung cancer evolution.

Authors:
Christopher Abbosh Nicolai J Birkbak Gareth A Wilson Mariam Jamal-Hanjani Tudor Constantin Raheleh Salari John Le Quesne David A Moore Selvaraju Veeriah Rachel Rosenthal Teresa Marafioti Eser Kirkizlar Thomas B K Watkins Nicholas McGranahan Sophia Ward Luke Martinson Joan Riley Francesco Fraioli Maise Al Bakir Eva Grönroos Francisco Zambrana Raymondo Endozo Wenya Linda Bi Fiona M Fennessy Nicole Sponer Diana Johnson Joanne Laycock Seema Shafi Justyna Czyzewska-Khan Andrew Rowan Tim Chambers Nik Matthews Samra Turajlic Crispin Hiley Siow Ming Lee Martin D Forster Tanya Ahmad Mary Falzon Elaine Borg David Lawrence Martin Hayward Shyam Kolvekar Nikolaos Panagiotopoulos Sam M Janes Ricky Thakrar Asia Ahmed Fiona Blackhall Yvonne Summers Dina Hafez Ashwini Naik Apratim Ganguly Stephanie Kareht Rajesh Shah Leena Joseph Anne Marie Quinn Phil A Crosbie Babu Naidu Gary Middleton Gerald Langman Simon Trotter Marianne Nicolson Hardy Remmen Keith Kerr Mahendran Chetty Lesley Gomersall Dean A Fennell Apostolos Nakas Sridhar Rathinam Girija Anand Sajid Khan Peter Russell Veni Ezhil Babikir Ismail Melanie Irvin-Sellers Vineet Prakash Jason F Lester Malgorzata Kornaszewska Richard Attanoos Haydn Adams Helen Davies Dahmane Oukrif Ayse U Akarca John A Hartley Helen L Lowe Sara Lock Natasha Iles Harriet Bell Yenting Ngai Greg Elgar Zoltan Szallasi Roland F Schwarz Javier Herrero Aengus Stewart Sergio A Quezada Karl S Peggs Peter Van Loo Caroline Dive C Jimmy Lin Matthew Rabinowitz Hugo J W L Aerts Allan Hackshaw Jacqui A Shaw Bernhard G Zimmermann Charles Swanton

Nature 2017 04;545(7655):446-451

Cancer Research UK Lung Cancer Centre of Excellence London and Manchester, University College London Cancer Institute, Paul O'Gorman Building, 72 Huntley Street, London WC1E 6DD, UK.

The early detection of relapse following primary surgery for non-small-cell lung cancer and the characterization of emerging subclones, which seed metastatic sites, might offer new therapeutic approaches for limiting tumour recurrence. The ability to track the evolutionary dynamics of early-stage lung cancer non-invasively in circulating tumour DNA (ctDNA) has not yet been demonstrated. Here we use a tumour-specific phylogenetic approach to profile the ctDNA of the first 100 TRACERx (Tracking Non-Small-Cell Lung Cancer Evolution Through Therapy (Rx)) study participants, including one patient who was also recruited to the PEACE (Posthumous Evaluation of Advanced Cancer Environment) post-mortem study. We identify independent predictors of ctDNA release and analyse the tumour-volume detection limit. Through blinded profiling of postoperative plasma, we observe evidence of adjuvant chemotherapy resistance and identify patients who are very likely to experience recurrence of their lung cancer. Finally, we show that phylogenetic ctDNA profiling tracks the subclonal nature of lung cancer relapse and metastasis, providing a new approach for ctDNA-driven therapeutic studies.
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http://dx.doi.org/10.1038/nature22364DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5812436PMC
April 2017

Tracking the Evolution of Non-Small-Cell Lung Cancer.

N Engl J Med 2017 06 26;376(22):2109-2121. Epub 2017 Apr 26.

From the Cancer Research UK Lung Cancer Centre of Excellence (M.J.-H., G.A.W., N. McGranahan, N.J.B., S.V., S.S., D.H.J., R.R., S.-M.L., M.D.F., C.A., S.M.J., C.D., C.S.), London and Manchester, Good Clinical Laboratory Practice Facility, University College London (UCL) Experimental Cancer Medicine Centre (H.L.L., J.A.H.), Bill Lyons Informatics Centre (J.H.), and Cancer Immunology Unit (S.A.Q.), UCL Cancer Institute, the Translational Cancer Therapeutics Laboratory (G.A.W., N. McGranahan, N.J.B., T.B.K.W., A.R., T.C., S. Turajlic, H.X., C.T.H., C.S.), Department of Bioinformatics and Biostatistics (R.M., M.S., S.H., M.E., A.S.), Advanced Sequencing Facility (N. Matthews), and Cancer Genomics Laboratory (S.D., P.V.L.), Francis Crick Institute, the Renal and Skin Units, Royal Marsden Hospital (S. Turajlic), the Departments of Medical Oncology (M.J.-H., S.-M.L., M.D.F., T.A., C.A., C.S.), Pathology (M.F., E.B., T.M.), Cardiothoracic Surgery (D.L., M.H., S. Kolvekar, N.P.), Respiratory Medicine (S.M.J., R.T.), and Radiology (A.A.), UCL Hospitals, Lungs for Living, UCL Respiratory, UCL (S.M.J.), the Department of Radiotherapy, North Middlesex University Hospital (G.A.), the Department of Respiratory Medicine, Royal Free Hospital (S. Khan), and UCL Cancer Research UK and Cancer Trials Centre (N.I., H.B., Y.N., A.H.), London, Cancer Studies, University of Leicester (D.A.M., D.A.F., J.A.S., J.L.Q.), the Department of Thoracic Surgery, Glenfield Hospital (A.N., S.R.), and the Medical Research Center Toxicology Unit (J.L.Q.), Leicester, the Institute of Cancer Studies, University of Manchester (F.B.), the Christie Hospital (F.B., Y.S.), the Departments of Cardiothoracic Surgery (R.S.) and Pathology (L.J., A.M.Q.) and the North West Lung Centre (P.A.C.), University Hospital of South Manchester, and Cancer Research UK Manchester Institute (C.D.), Manchester, the Departments of Thoracic Surgery (B.N.) and Cellular Pathology (G.L., S. Trotter), Birmingham Heartlands Hospital, Molecular Pathology Diagnostic Services, Queen Elizabeth Hospital (P.T., B.O.), and Institute of Immunology and Immunotherapy, University of Birmingham (G.M.), Birmingham, the Departments of Medical Oncology (M.N.), Cardiothoracic Surgery (H.R.), Pathology (K.K.), Respiratory Medicine (M.C.), and Radiology (L.G.), Aberdeen University Medical School and Aberdeen Royal Infirmary, Aberdeen, the Department of Respiratory Medicine, Barnet and Chase Farm Hospitals, Barnet (S. Khan), the Department of Respiratory Medicine, Princess Alexandra Hospital, Harlow (P.R.), the Department of Clinical Oncology, St. Luke's Cancer Centre, Guildford (V.E.), the Departments of Pathology (B.I.), Respiratory Medicine (M.I.-S.), and Radiology (V.P.), Ashford and St. Peters' Hospitals, Surrey, the Department of Clinical Oncology, Velindre Hospital (J.F.L.), the Departments of Radiology (H.A.) and Respiratory Medicine (H.D.), University Hospital Llandough, the Departments of Pathology (R.A.) and Cardiothoracic Surgery (M.K.), University Hospital of Wales, and Cardiff University (R.A.), Cardiff, and Wellcome Trust Sanger Institute, Hinxton, and Big Data Institute, University of Oxford, Oxford (S.D.) - all in the United Kingdom; the Center for Biological Sequence Analysis, Department of Systems Biology, Technical University of Denmark, Lyngby (Z.S.); the Computational Health Informatics Program, Boston Children's Hospital and Harvard Medical School, Boston (Z.S.); MTA-SE-NAP, Brain Metastasis Research Group, 2nd Department of Pathology, Semmelweis University, Budapest, Hungary (Z.S.); Berlin Institute for Medical Systems Biology, Max Delbrueck Center for Molecular Medicine, Berlin (R.F.S.); and the Department of Human Genetics, University of Leuven, Leuven, Belgium (P.V.L.).

Background: Among patients with non-small-cell lung cancer (NSCLC), data on intratumor heterogeneity and cancer genome evolution have been limited to small retrospective cohorts. We wanted to prospectively investigate intratumor heterogeneity in relation to clinical outcome and to determine the clonal nature of driver events and evolutionary processes in early-stage NSCLC.

Methods: In this prospective cohort study, we performed multiregion whole-exome sequencing on 100 early-stage NSCLC tumors that had been resected before systemic therapy. We sequenced and analyzed 327 tumor regions to define evolutionary histories, obtain a census of clonal and subclonal events, and assess the relationship between intratumor heterogeneity and recurrence-free survival.

Results: We observed widespread intratumor heterogeneity for both somatic copy-number alterations and mutations. Driver mutations in EGFR, MET, BRAF, and TP53 were almost always clonal. However, heterogeneous driver alterations that occurred later in evolution were found in more than 75% of the tumors and were common in PIK3CA and NF1 and in genes that are involved in chromatin modification and DNA damage response and repair. Genome doubling and ongoing dynamic chromosomal instability were associated with intratumor heterogeneity and resulted in parallel evolution of driver somatic copy-number alterations, including amplifications in CDK4, FOXA1, and BCL11A. Elevated copy-number heterogeneity was associated with an increased risk of recurrence or death (hazard ratio, 4.9; P=4.4×10), which remained significant in multivariate analysis.

Conclusions: Intratumor heterogeneity mediated through chromosome instability was associated with an increased risk of recurrence or death, a finding that supports the potential value of chromosome instability as a prognostic predictor. (Funded by Cancer Research UK and others; TRACERx ClinicalTrials.gov number, NCT01888601 .).
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http://dx.doi.org/10.1056/NEJMoa1616288DOI Listing
June 2017

Synthesis and in vitro evaluation of SG3227, a pyrrolobenzodiazepine dimer antibody-drug conjugate payload based on sibiromycin.

Bioorg Med Chem Lett 2017 03 30;27(5):1154-1158. Epub 2017 Jan 30.

Spirogen, QMB Innovation Centre, 42 New Road, London E1 2AX, UK. Electronic address:

A novel pyrrolobenzodiazepine dimer payload, SG3227, was rationally designed based on the naturally occurring antitumour compound sibiromycin. SG3227 was synthesized from a dimeric core in an efficient fashion. An unexpected room temperature Diels-Alder reaction occurred during the final step of the synthesis and was circumvented by use of an iodoacetamide conjugation moiety in place of a maleimide. The payload was successfully conjugated to trastuzumab and the resulting ADC exhibited potent activity against a HER2-expressing human cancer cell line in vitro.
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http://dx.doi.org/10.1016/j.bmcl.2017.01.074DOI Listing
March 2017

Design and Synthesis of Tesirine, a Clinical Antibody-Drug Conjugate Pyrrolobenzodiazepine Dimer Payload.

ACS Med Chem Lett 2016 Nov 24;7(11):983-987. Epub 2016 May 24.

QMB Innovation Centre, Spirogen , 42 New Road, E1 2AX London, U.K.

Pyrrolobenzodiazepine dimers are an emerging class of warhead in the field of antibody-drug conjugates (ADCs). Tesirine (SG3249) was designed to combine potent antitumor activity with desirable physicochemical properties such as favorable hydrophobicity and improved conjugation characteristics. One of the reactive imines was capped with a cathepsin B-cleavable valine-alanine linker. A robust synthetic route was developed to allow the production of tesirine on clinical scale, employing a flexible, convergent strategy. Tesirine was evaluated both in stochastic and engineered ADC constructs and was confirmed as a potent and versatile payload. The conjugation of tesirine to anti-DLL3 rovalpituzumab has resulted in rovalpituzumab-tesirine (Rova-T), currently under evaluation for the treatment of small cell lung cancer.
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http://dx.doi.org/10.1021/acsmedchemlett.6b00062DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5108040PMC
November 2016

Expression of somatostatin receptors 2 and 5 in circulating tumour cells from patients with neuroendocrine tumours.

Br J Cancer 2016 Dec 22;115(12):1540-1547. Epub 2016 Nov 22.

UCL Cancer Institute, University College London, London WC1E 6DD, UK.

Background: Neuroendocrine tumours (NET) overexpress somatostatin receptors (SSTR) that can be targeted for therapy. Somatostatin receptor expression is routinely measured by molecular imaging but the resolution is insufficient to define heterogeneity. We hypothesised that SSTR expression could be measured on circulating tumour cells (CTCs) and used to investigate heterogeneity of expression and track changes during therapy.

Methods: MCF-7 cells were transfected with SSTR2 or 5 and spiked into donor blood for analysis by CellSearch. Optimum anti-SSTR antibody concentration and exposure time were determined, and flow cytometry was used to evaluate assay sensitivity. For clinical evaluation, blood was analysed by CellSearch, and SSTR2/5 immunohistochemistry was performed on matched tissue samples.

Results: Flow cytometry confirmed CellSearch was sensitive and that detection of SSTR was unaffected by the presence of somatostatin analogue up to a concentration of 100 ng ml. Thirty-one NET patients were recruited: grade; G1 (29%), G2 (45%), G3 (13%), primary site; midgut (58%), pancreatic (39%). Overall, 87% had SSTR-positive tumours according to somatostatin receptor scintigraphy or 68-Ga-DOTATE PET/CT. Circulating tumour cells were detected in 21 out of 31 patients (68%), of which 33% had evidence of heterogeneous expression of either SSTR2 (n=5) or SSTR5 (n=2).

Conclusions: Somatostatin receptors 2 and 5 are detectable on CTCs from NET patients and may be a useful biomarker for evaluating SSTR-targeted therapies and this is being prospectively evaluated in the Phase IV CALMNET trial (NCT02075606).
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http://dx.doi.org/10.1038/bjc.2016.377DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5155369PMC
December 2016

ADCT-301, a Pyrrolobenzodiazepine (PBD) Dimer-Containing Antibody-Drug Conjugate (ADC) Targeting CD25-Expressing Hematological Malignancies.

Mol Cancer Ther 2016 11 17;15(11):2709-2721. Epub 2016 Aug 17.

Cancer Research UK Drug DNA Interactions Research Group, UCL Cancer Institute, London, United Kingdom.

Despite the many advances in the treatment of hematologic malignancies over the past decade, outcomes in refractory lymphomas remain poor. One potential strategy in this patient population is the specific targeting of IL2R-α (CD25), which is overexpressed on many lymphoma and leukemic cells, using antibody-drug conjugates (ADC). ADCT-301 is an ADC composed of human IgG1 HuMax-TAC against CD25, stochastically conjugated through a dipeptide cleavable linker to a pyrrolobenzodiazepine (PBD) dimer warhead with a drug-antibody ratio (DAR) of 2.3. ADCT-301 binds human CD25 with picomolar affinity. ADCT-301 has highly potent and selective cytotoxicity against a panel of CD25-expressing human lymphoma cell lines. Once internalized, the released warhead binds in the DNA minor groove and exerts its potent cytotoxic action via the formation of DNA interstrand cross-links. A strong correlation between loss of viability and DNA cross-link formation is demonstrated. DNA damage persists, resulting in phosphorylation of histone H2AX, cell-cycle arrest in G-M, and apoptosis. Bystander killing of CD25-negative cells by ADCT-301 is also observed. In vivo, a single dose of ADCT-301 results in dose-dependent and targeted antitumor activity against both subcutaneous and disseminated CD25-positive lymphoma models. In xenografts of Karpas 299, which expressed both CD25 and CD30, marked superiority over brentuximab vedotin (Adcetris) is observed. Dose-dependent increases in DNA cross-linking, γ-H2AX, and PBD payload staining were observed in tumors in vivo indicating a role as relevant pharmacodynamic assays. Together, these data support the clinical testing of this novel ADC in patients with CD25-expressing tumors. Mol Cancer Ther; 15(11); 2709-21. ©2016 AACR.
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http://dx.doi.org/10.1158/1535-7163.MCT-16-0233DOI Listing
November 2016

Modulation of topoisomerase IIα expression and chemosensitivity through targeted inhibition of NF-Y:DNA binding by a diamino p-anisyl-benzimidazole (Hx) polyamide.

Biochim Biophys Acta Gene Regul Mech 2017 May 24;1860(5):617-629. Epub 2016 Oct 24.

Cancer Research UK Drug-DNA Interactions Research Group, UCL Cancer Institute, London, WC1E 6BT, UK. Electronic address:

Background: Sequence specific polyamide HxIP 1, targeted to the inverted CCAAT Box 2 (ICB2) on the topoisomerase IIα (topo IIα) promoter can inhibit NF-Y binding, re-induce gene expression and increase sensitivity to etoposide. To enhance biological activity, diamino-containing derivatives (HxI*P 2 and HxIP* 3) were synthesised incorporating an alkyl amino group at the N1-heterocyclic position of the imidazole/pyrrole.

Methods: DNase I footprinting was used to evaluate DNA binding of the diamino Hx-polyamides, and their ability to disrupt the NF-Y:ICB2 interaction assessed using EMSAs. Topo IIα mRNA (RT-PCR) and protein (Immunoblotting) levels were measured following 18h polyamide treatment of confluent A549 cells. γH2AX was used as a marker for etoposide-induced DNA damage after pre-treatment with HxIP* 3 and cell viability was measured using Cell-Titer Glo®.

Results: Introduction of the N1-alkyl amino group reduced selectivity for the target sequence 5'-TACGAT-3' on the topo IIα promoter, but increased DNA binding affinity. Confocal microscopy revealed both fluorescent diamino polyamides localised in the nucleus, yet HxI*P 2 was unable to disrupt the NF-Y:ICB2 interaction and showed no effect against the downregulation of topo IIα. In contrast, inhibition of NF-Y binding by HxIP* 3 stimulated dose-dependent (0.1-2μM) re-induction of topo IIα and potentiated cytotoxicity of topo II poisons by enhancing DNA damage.

Conclusions: Polyamide functionalisation at the N1-position offers a design strategy to improve drug-like properties. Dicationic HxIP* 3 increased topo IIα expression and chemosensitivity to topo II-targeting agents.

General Significance: Pharmacological modulation of topo IIα expression has the potential to enhance cellular sensitivity to clinically-used anticancer therapeutics. This article is part of a Special Issue entitled: Nuclear Factor Y in Development and Disease, edited by Prof. Roberto Mantovani.
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http://dx.doi.org/10.1016/j.bbagrm.2016.10.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5757371PMC
May 2017

The MEK1/2 Inhibitor Pimasertib Enhances Gemcitabine Efficacy-Response.

Clin Cancer Res 2016 05;22(10):2595

UCL Cancer Institute, University College of London, London, United Kingdom.

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http://dx.doi.org/10.1158/1078-0432.CCR-16-0566DOI Listing
May 2016

Role of Reactive Oxygen Species in the Abrogation of Oxaliplatin Activity by Cetuximab in Colorectal Cancer.

J Natl Cancer Inst 2016 Jun 30;108(6):djv394. Epub 2015 Dec 30.

Cancer Research UK Drug-DNA Interactions Research Group, UCL Cancer Institute, University College London, London, UK (VS, RJ, KK, JAH, DH); Colorectal Cancer Genetics Group, Blizard Institute, London, UK (HT, AN, RJ, ARS);

Background: The antibody cetuximab, targeting epidermal growth factor receptor (EGFR), is used to treat metastatic colorectal cancer (mCRC). Clinical trials suggest reduced benefit from the combination of cetuximab with oxaliplatin. The aim of this study was to investigate potential negative interactions between cetuximab and oxaliplatin.

Methods: Thiazolyl blue tetrazolium bromide (MTT) assay and Calcusyn software were used to characterize drug interactions. Reactive oxygen species (ROS) were measured by flow cytometry and real-time polymerase chain reaction oxidative stress arrays identified genes regulating ROS production. Chromatin immunoprecipitation (ChIP) measured signal transducer and activator of transcription 1 (STAT-1) binding to dual oxidase 2 (DUOX2) promoter. SW48, DLD-1 KRAS wild-type cell lines and DLD-1 xenograft models exposed to cetuximab, oxaliplatin, or oxaliplatin + cetuximab (control [saline]; n = 3 mice per treatment group) were used. Statistical tests were two-sided.

Results: Cetuximab and oxaliplatin exhibited antagonistic effects on cellular proliferation and apoptosis (caspase 3/7 activity reduced by 1.4-fold, 95% confidence interval [CI] = 0.78 to 2.11, P = .003) as opposed to synergistic effects observed with the irinotecan metabolite 7-Ethyl-10-hydroxycamptothecin (SN-38). Although both oxaliplatin and SN-38 produced ROS, only oxaliplatin-mediated apoptosis was ROS dependent. Production of ROS by oxaliplatin was secondary to STAT1-mediated transcriptional upregulation of DUOX2 (3.1-fold, 95% CI = 1.75 to 2.41, P < .001). Inhibition of DUOX2 induction and p38 activation by cetuximab reduced oxaliplatin cytotoxicity.

Conclusions: Inhibition of STAT1 and DUOX2-mediated ROS generation by cetuximab impairs p38-dependent apoptosis by oxaliplatin in preclinical models and may contribute to reduced efficacy in clinical settings. Understanding the rationale for unexpected trial results will inform improved rationales for combining EGFR inhibitors with chemotherapeutic agents in future therapeutic use.
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http://dx.doi.org/10.1093/jnci/djv394DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4864961PMC
June 2016

NF-Y activates genes of metabolic pathways altered in cancer cells.

Oncotarget 2016 Jan;7(2):1633-50

Dipartimento di Bioscienze, Università degli Studi di Milano, Milano, Italy.

The trimeric transcription factor NF-Y binds to the CCAAT box, an element enriched in promoters of genes overexpressed in tumors. Previous studies on the NF-Y regulome identified the general term metabolism as significantly enriched. We dissect here in detail the targeting of metabolic genes by integrating analysis of NF-Y genomic binding and profilings after inactivation of NF-Y subunits in different cell types. NF-Y controls de novo biosynthetic pathways of lipids, teaming up with the master SREBPs regulators. It activates glycolytic genes, but, surprisingly, is neutral or represses mitochondrial respiratory genes. NF-Y targets the SOCG (Serine, One Carbon, Glycine) and Glutamine pathways, as well as genes involved in the biosynthesis of polyamines and purines. Specific cancer-driving nodes are generally under NF-Y control. Altogether, these data delineate a coherent strategy to promote expression of metabolic genes fuelling anaerobic energy production and other anabolic pathways commonly altered in cancer cells.
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http://dx.doi.org/10.18632/oncotarget.6453DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4811486PMC
January 2016

Genetically Encoded Azide Containing Amino Acid in Mammalian Cells Enables Site-Specific Antibody-Drug Conjugates Using Click Cycloaddition Chemistry.

Bioconjug Chem 2015 Nov 11;26(11):2249-60. Epub 2015 Sep 11.

Allozyne, Inc. , 1600 Fairview Avenue East, Seattle, Washington 98102, United States.

Antibody-drug conjugates (ADC) have emerged as potent antitumor drugs that provide increased efficacy, specificity, and tolerability over chemotherapy for the treatment of cancer. ADCs generated by targeting cysteines and lysines on the antibody have shown efficacy, but these products are heterogeneous, and instability may limit their dosing. Here, a novel technology is described that enables site-specific conjugation of toxins to antibodies using chemistry to produce homogeneous, potent, and highly stable conjugates. We have developed a cell-based mammalian expression system capable of site-specific integration of a non-natural amino acid containing an azide moiety. The azide group enables click cycloaddition chemistry that generates a stable heterocyclic triazole linkage. Antibodies to Her2/neu were expressed to contain N6-((2-azidoethoxy)carbonyl)-l-lysine at four different positions. Each site allowed over 95% conjugation efficacy with the toxins auristatin F or a pyrrolobenzodiazepine (PBD) dimer to generate ADCs with a drug to antibody ratio of >1.9. The ADCs were potent and specific in in vitro cytotoxicity assays. An anti Her2/neu conjugate demonstrated stability in vivo and a PBD containing ADC showed potent efficacy in a mouse tumor xenograph model. This technology was extended to generate fully functional ADCs with four toxins per antibody. The high stability of the azide-alkyne linkage, combined with the site-specific nature of the expression system, provides a means for the generation of ADCs with optimized pharmacokinetic, biological, and biophysical properties.
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http://dx.doi.org/10.1021/acs.bioconjchem.5b00359DOI Listing
November 2015

Activity of the DNA minor groove cross-linking agent SG2000 (SJG-136) against canine tumours.

BMC Vet Res 2015 Aug 19;11:215. Epub 2015 Aug 19.

CR-UK Drug-DNA Interactions Research Group, UCL Cancer Institute, Paul O'Gorman Building, University College London, 72 Huntley Street, London, WC1E 6BT, UK.

Background: Cancer is the leading cause of death in older dogs and its prevalence is increasing. There is clearly a need to develop more effective anti-cancer drugs in dogs. SG2000 (SJG-136) is a sequence selective DNA minor groove cross-linking agent. Based on its in vitro potency, the spectrum of in vivo and clinical activity against human tumours, and its tolerability in human patients, SG2000 has potential as a novel therapeutic against spontaneously occurring canine malignancies.

Results: In vitro cytotoxicity was assessed using SRB and MTT assays, and in vivo activity was assessed using canine tumour xenografts. DNA interstrand cross-linking (ICL) was determined using a modification of the single cell gel electrophoresis (comet) assay. Effects on cell cycle distribution were assessed by flow cytometry and measurement of γ-H2AX by immunofluorescence and immunohistochemistry. SG2000 had a multi-log differential cytotoxic profile against a panel of 12 canine tumour cell lines representing a range of common tumour types in dogs. In the CMeC-1 melanoma cell line, DNA ICLs increased linearly with dose following a 1 h treatment. Peak ICL was achieved within 1 h and no removal was observed over 48 h. A relationship between DNA ICL formation and cytotoxicity was observed across cell lines. The formation of γ-H2AX foci was slow, becoming evident after 4 h and reaching a peak at 24 h. SG2000 exhibited significant anti-tumour activity against two canine melanoma tumour models in vivo. Anti-tumour activity was observed at 0.15 and 0.3 mg/kg given i.v. either once, or weekly x 3. Dose-dependent DNA ICL was observed in tumours (and to a lower level in peripheral blood mononuclear cells) at 2 h and persisted at 24 h. ICL increased following the second and third doses in a repeated dose schedule. At 24 h, dose dependent γ-H2AX foci were more numerous than at 2 h, and greater in tumours than in peripheral blood mononuclear cells. SG2000-induced H2AX phosphorylation measured by immunohistochemistry showed good correspondence, but less sensitivity, than measurement of foci.

Conclusions: SG2000 displayed potent activity in vitro against canine cancer cell lines as a result of the formation and persistence of DNA ICLs. SG2000 also had significant in vivo antitumour activity against canine melanoma xenografts, and the comet and γ-H2AX foci methods were relevant pharmacodynamic assays. The clinical testing of SG2000 against spontaneous canine cancer is warranted.
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http://dx.doi.org/10.1186/s12917-015-0534-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4539724PMC
August 2015