Combinatorial Ubiquitination REal-time PROteolysis (CURE-PROs): A Modular Platform for Generating Reversible, Self-Assembling Bifunctional Targeted Degraders

Proteolysis-Targeting Chimeras (PROTACs) are bifunctional molecules that bring a target protein and an E3 ubiquitin ligase into proximity to append ubiquitin, thus directing target degradation. Although numerous PROTACs have entered clinical trials, their development remains challenging, and their large size can produce poor drug-like properties. To overcome these limitations, we have modified our Coferon platform to generate Combinatorial Ubiquitination REal-time PROteolysis (CURE-PROs). CURE-PROs are small molecule degraders designed to self-assemble through reversible bio-orthogonal linkers to form covalent heterodimers. By modifying known ligands for Cereblon, MDM2, VHL, and BRD with complementary phenylboronic acid and diol/catechol linkers, we have successfully created CURE-PROs that direct degradation of BRD4 both in vitro and in vivo. The combinatorial nature of our platform significantly reduces synthesis time and effort to identify the optimal linker length and E3 ligase partner to each target and is readily amenable to screening for new targets.

An anchor-tether 'hindered' HCN1 inhibitor is antihyperalgesic in a rat spared nerve injury neuropathic pain model

BACKGROUND

Neuropathic pain impairs quality of life, is widely prevalent, and incurs significant costs. Current pharmacological therapies have poor/no efficacy and significant adverse effects; safe and effective alternatives are needed. Hyperpolarisation-activated cyclic nucleotide-regulated (HCN) channels are causally implicated in some forms of peripherally mediated neuropathic pain. Whilst 2,6-substituted phenols, such as 2,6-di-tert-butylphenol (26DTB-P), selectively inhibit HCN1 gating and are antihyperalgesic, the development of therapeutically tolerable, HCN-selective antihyperalgesics based on their inverse agonist activity requires that such drugs spare the cardiac isoforms and do not cross the blood-brain barrier.

METHODS

In silico molecular dynamics simulation, in vitro electrophysiology, and in vivo rat spared nerve injury methods were used to test whether 'hindered' variants of 26DTB-P (wherein a hydrophilic 'anchor' is attached in the para-position of 26DTB-P via an acyl chain 'tether') had the desired properties.

RESULTS

Molecular dynamics simulation showed that membrane penetration of hindered 26DTB-Ps is controlled by a tethered diol anchor without elimination of head group rotational freedom. In vitro and in vivo analysis showed that BP4L-18:1:1, a variant wherein a diol anchor is attached to 26DTB-P via an 18-carbon tether, is an HCN1 inverse agonist and an orally available antihyperalgesic. With a CNS multiparameter optimisation score of 2.25, a >100-fold lower drug load in the brain vs blood, and an absence of adverse cardiovascular or CNS effects, BP4L-18:1:1 was shown to be poorly CNS penetrant and cardiac sparing.

CONCLUSIONS

These findings provide a proof-of-concept demonstration that anchor-tethered drugs are a new chemotype for treatment of disorders involving membrane targets.

Probucol is anti-hyperalgesic in a mouse peripheral nerve injury model of neuropathic pain

2,6-di-tert-butylphenol (2,6-DTBP) ameliorates mechanical allodynia and thermal hyperalgesia produced by partial sciatic nerve ligation in mice, and selectively inhibits HCN1 channel gating. We hypothesized that the clinically utilized non-anesthetic dimerized congener of 2,6-DTBP, probucol (2,6-di-tert-butyl-4-[2-(3,5-di-tert-butyl-4-hydroxyphenyl)sulfanylpropan-2-ylsulfanyl]phenol), would relieve the neuropathic phenotype that results from peripheral nerve damage, and that the anti-hyperalgesic efficacy in vivo would correlate with HCN1 channel inhibition in vitro. A single oral dose of probucol (800 mg/kg) relieved mechanical allodynia and thermal hyperalgesia in a mouse spared-nerve injury neuropathic pain model. While the low aqueous solubility of probucol precluded assessment of its possible interaction with HCN1 channels, our results, in conjunction with recent data demonstrating that probucol reduces lipopolysaccharide-induced mechanical allodynia and thermal hyperalgesia, support the testing/development of probucol as a non-opioid, oral antihyperalgesic albeit one of unknown mechanistic action.

Results from a randomised controlled pilot study of the Better Conversations with Primary Progressive Aphasia (BCPPA) communication partner training program for people with PPA and their communication partners

BACKGROUND

There has been a growing focus on functional communication interventions for primary progressive aphasia (PPA). These interventions aim to support individuals to participate in life situations. One such intervention, communication partner training (CPT) aims to change conversation behaviours in both the person with PPA and their communication partner (CP). CPT has a growing evidence base in stroke aphasia; however, these programmes are not designed to meet the needs of people with progressive communication difficulties. To address this, the authors developed a CPT program entitled Better Conversations with PPA (BCPPA) and undertook a pilot trial to establish for a future full trial; predicted recruitment rates, acceptability, an assessment of treatment fidelity and an appropriate primary outcome measure.

METHODOLOGY

This was a single-blind, randomised controlled pilot study comparing BCPPA to no treatment, delivered across 11 National Health Service Trusts in the UK. A random sample of eight recordings of local collaborators delivering the intervention were analysed to examine fidelity. Participants completed feedback forms reporting on acceptability. Pre- and post-intervention measures targeted conversation behaviours, communication goals and quality of life.

RESULTS

Eighteen people with PPA and their CPs (9 randomised to BCPPA, 9 randomised to no treatment) completed the study. Participants in the intervention group rated BCPPA positively. Treatment fidelity was 87.2%. Twenty-nine of 30 intervention goals were achieved or over-achieved and 16 of 30 coded conversation behaviours demonstrated change in the intended direction. The Aphasia Impact Questionnaire was identified as the preferred outcome measure.

CONCLUSION

The first randomised controlled UK pilot study of a CPT program for people with PPA and their families demonstrates BCPPA is a promising intervention. The intervention was acceptable, treatment fidelity high and an appropriate measure identified. Results of this study indicate a future RCT of BCPPA is feasible.

TRIAL REGISTRATION

Registered 28/02/2018 ISRCTN10148247 .

Tetrathiomolybdate (TM)-associated copper depletion influences collagen remodeling and immune response in the pre-metastatic niche of breast cancer

Tetrathiomolybdate (TM) is a novel, copper-depleting compound associated with promising survival in a phase II study of patients with high-risk and triple-negative breast cancer. We sought to elucidate the mechanism of TM by exploring its effects on collagen processing and immune function in the tumor microenvironment (TME). Using an exploratory cohort, we identified markers of collagen processing (LOXL2, PRO-C3, C6M, and C1M) that differed between those with breast cancer versus controls. We measured these collagen biomarkers in TM-treated patients on the phase II study and detected evidence of decreased collagen cross-linking and increased degradation over formation in those without disease compared to those who experienced disease progression. Preclinical studies revealed decreased collagen deposition, lower levels of myeloid-derived suppressor cells, and higher CD4+ T-cell infiltration in TM-treated mice compared with controls. This study reveals novel mechanisms of TM targeting the TME and immune response with potential applications across cancer types.

PROTACs: Promising Approaches for Epigenetic Strategies to Overcome Drug Resistance

Epigenetic modulation of gene expression is essential for tissue-specific development and maintenance in mammalian cells. Disruption of epigenetic processes, and the subsequent alteration of gene functions, can result in inappropriate activation or inhibition of various cellular signaling pathways, leading to cancer. Recent advancements in the understanding of the role of epigenetics in cancer initiation and progression have uncovered functions for DNA methylation, histone modifications, nucleosome positioning, and non-coding RNAs. Epigenetic therapies have shown some promise for hematological malignancies, and a wide range of epigenetic-based drugs are undergoing clinical trials. However, in a dynamic survival strategy, cancer cells exploit their heterogeneous population which frequently results in the rapid acquisition of therapy resistance. Here, we describe novel approaches in drug discovery targeting the epigenome, highlighting recent advances the selective degradation of target proteins using Proteolysis Targeting Chimera (PROTAC) to address drug resistance.

Predictors for a dementia gene mutation based on gene-panel next-generation sequencing of a large dementia referral series

Next-generation genetic sequencing (NGS) technologies facilitate the screening of multiple genes linked to neurodegenerative dementia, but there are few reports about their use in clinical practice. Which patients would most profit from testing, and information on the likelihood of discovery of a causal variant in a clinical syndrome, are conspicuously absent from the literature, mostly for a lack of large-scale studies. We applied a validated NGS dementia panel to 3241 patients with dementia and healthy aged controls; 13,152 variants were classified by likelihood of pathogenicity. We identified 354 deleterious variants (DV, 12.6% of patients); 39 were novel DVs. Age at clinical onset, clinical syndrome and family history each strongly predict the likelihood of finding a DV, but healthcare setting and gender did not. DVs were frequently found in genes not usually associated with the clinical syndrome. Patients recruited from primary referral centres were compared with those seen at higher-level research centres and a national clinical neurogenetic laboratory; rates of discovery were comparable, making selection bias unlikely and the results generalisable to clinical practice. We estimated penetrance of DVs using large-scale online genomic population databases and found 71 with evidence of reduced penetrance. Two DVs in the same patient were found more frequently than expected. These data should provide a basis for more informed counselling and clinical decision making.

Structure-Activity Relationships of Noncovalent Immunoproteasome β5i-Selective Dipeptides

The immunoproteasome (i-20S) has emerged as a therapeutic target for autoimmune and inflammatory disorders and hematological malignancies. Inhibition of the chymotryptic β5i subunit of i-20S inhibits T cell activation, B cell proliferation, and dendritic cell differentiation in vitro and suppresses immune responses in animal models of autoimmune disorders and allograft rejection. However, cytotoxicity to immune cells has accompanied the use of covalently reactive β5i inhibitors, whose activity against the constitutive proteasome (c-20S) is cumulative with the time of exposure. Herein, we report a structure-activity relationship study of a class of noncovalent proteasome inhibitors with picomolar potencies and 1000-fold selectivity for i-20S over c-20S. Furthermore, these inhibitors are specific for β5i over the other five active subunits of i-20S and c-20S, providing useful tools to study the functions of β5i in immune responses. The potency of these compounds in inhibiting human T cell activation suggests that they may have therapeutic potential.

Avian agnosia: A window into auditory semantics

The functional and neural organisation of auditory knowledge is relatively poorly understood. The breakdown of conceptual knowledge in semantic dementia has revealed that pre-morbid expertise influences the extent to which knowledge is differentiated. Whether this principle applies to a similar extent in the auditory domain is not yet known. Previous reports of patients with impaired auditory vs. intact visual expert knowledge suggest that expertise may have differential effects upon the organisation of auditory and visual knowledge. An equally plausible alternative, however, is that auditory knowledge is simply more vulnerable to deterioration. Thus, expertise effects in the auditory domain may not yet have been observed because knowledge of auditory expert vs. non-expert knowledge has yet to be compared. We had the opportunity to address this issue by studying SA, a patient with semantic dementia and extensive pre-morbid knowledge of birds. We undertook a systematic investigation of SA's auditory vs. visual knowledge from matched expert vs. non-expert categories. Relative to a group of 10 age, education and IQ matched bird experts, SA showed impaired auditory vs. intact visual avian knowledge, despite intact basic auditory perceptual abilities. This was explained by independent effects of modality and expertise. Thus, he was also disproportionately impaired for auditory vs. visual knowledge of items from non-expert categories. In both auditory and visual modalities, his performance was relatively more impaired on tests of non-expert vs. expert knowledge. These findings suggest that, while auditory knowledge may be more vulnerable to deterioration, expertise modulates visual and auditory knowledge to a similar extent.

Abstract PD9-07: A phase II study of copper-depletion using tetrathiomolybdate (TM) in patients (pts) with high risk breast cancer (BC): Role of collagen processing and tumor microenvironment

Background: Copper is an important catalytic cofactor in several biological functions and is essential for lysyl oxidase (LOX), a key enzyme in cross-linking collagen, which may play a role in tumor metastasis. We hypothesized that tetrathiomolybdate (TM)-associated copper depletion (CD) would inhibit tumor metastases by altering copper dependent collagen remodeling in the pre-metastatic niche. These results are an update of our previously reported clinical outcomes with longer follow-up and translational outcomes implicating the tumor microenvironment in metastatic transformation of BC. Methods: Pts at high risk for recurrence, node+ triple negative (TNBC) or stage 3/4 BC with no evidence of disease (NED), were enrolled on a phase II study of CD with TM. TM was given to maintain ceruloplasmin (Cp) levels between 8-16 mg/dl for two years (yrs) with an extension phase or until relapse. Median Cp levels were monitored with each cycle. Clinical endpoints included safety/tolerability and progression of disease (POD)/death. Event-free (EFS) and overall survival (OS) were calculated using Kaplan Meier survival analyses. Translational endpoints included markers of collagen cross-linking (LOXL-2), formation (PRO-C3), and degradation (C1M and C6M). Results: Seventy-five pts received 2993 cycles of TM on the primary (24 cycles, 28 days per cycle) and extension study. Median age was 51 yrs (range 29-66). Forty-five pts had stage 2/3 BC, and 30 pts were stage 4 NED. At a median follow-up of 8.4 yrs, the overall EFS was 71.4% and OS was 78.8%. The EFS and OS for the 36 pts with TNBC were 71.7% and 81%, and the EFS and OS for the 39 pts with Luminal/HER2+ BC were 71.2% and 78.6% respectively. TM was well tolerated with grade 3/4 toxicities including: neutropenia (1.9%), febrile neutropenia (0.03%), and fatigue (0.2%). LOXL2 levels were significantly decreased at 12 and 24 cycles compared with baseline (p<0.01) in those who were NED but not in those who had progressive disease (POD). LOXL2 levels were significantly correlated with C1M levels (spearman coefficient -0.34, p=0.02). C1M levels were significantly increased at 5, 11 and 24 cycles as compared with baseline (p<0.01) in those who were NED and were significantly higher as compared to levels in those experiencing POD/death, p<0.05. This difference may be more pronounced in those not achieving adequate CD (<50%) and in luminal/HER2+ BC. Interestingly, the ratio of C1M/PRO-C3 was significantly more elevated over time in those NED as compared to those experiencing POD/death. No associations were found with other collagen markers (PRO-C3 and C6M). Conclusions: TM is safe, well-tolerated and associated with decreased LOXL-2 and increased C1M levels over time in NED pts. This suggests that copper depletion may result in decreased collagen crosslinking and increased collagen degradation over formation, potentially “normalizing” the collagen microenvironment to create an inhospitable environment for tumor metastases. Larger randomized trials in high risk populations with translational outcomes are needed to further investigate the role of collagen processing in the tumor microenvironment and its potential as a biomarker of response.

Citation Format: Liu YL, Bager CL, Willumsen N, Kornhauser N, Cobham M, Andreopoulou E, Cigler T, Moore A, LaPolla D, Fitzpatrick V, Ward M, Warren JD, Mittal V, Vahdat LT. A phase II study of copper-depletion using tetrathiomolybdate (TM) in patients (pts) with high risk breast cancer (BC): Role of collagen processing and tumor microenvironment [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD9-07.

Alkylphenol inverse agonists of HCN1 gating: H-bond propensity, ring saturation and adduct geometry differentially determine efficacy and potency

BACKGROUND AND PURPOSE

In models of neuropathic pain, inhibition of HCN1 is anti-hyperalgesic. 2,6-di-iso-propyl phenol (propofol) and its non-anesthetic congener, 2,6-di-tert-butyl phenol, inhibit HCN1 channels by stabilizing closed state(s).

EXPERIMENTAL APPROACH

Using in vitro electrophysiology and kinetic modeling, we systematically explore the contribution of ligand architecture to alkylphenol-channel coupling.

KEY RESULTS

When corrected for changes in hydrophobicity (and propensity for intra-membrane partitioning), the decrease in potency upon 1-position substitution (NCO∼OH >> SH >>> F) mirrors the ligands' H-bond acceptor (NCO > OH > SH >>> F) but not donor profile (OH > SH >>> NCO∼F). H-bond elimination (OH to F) corresponds to a ΔΔG of ∼4.5 kCal mol^-1 loss of potency with little or no disruption of efficacy. Substitution of compact alkyl groups (iso-propyl, tert-butyl) with shorter (ethyl, methyl) or more extended (sec-butyl) adducts disrupts both potency and efficacy. Ring saturation (with the obligate loss of both planarity and π electrons) primarily disrupts efficacy.

CONCLUSIONS AND IMPLICATIONS

A hydrophobicity-independent decrement in potency at higher volumes suggests the alkylbenzene site has a volume of ≥800 ų. Within this, a relatively static (with respect to ligand) H-bond donor contributes to initial binding with little involvement in generation of coupling energy. The influence of π electrons/ring planarity and alkyl adducts on efficacy reveals these aspects of the ligand present towards a face of the channel that undergoes structural changes during opening. The site's characteristics suggest it is "druggable"; introduction of other adducts on the ring may generate higher potency inverse agonists.

Identification of a Mycothiol-Dependent Nitroreductase from Mycobacterium tuberculosis

The success of Mycobacterium tuberculosis (Mtb) as a pathogen depends on the redundant and complex mechanisms it has evolved for resisting nitrosative and oxidative stresses inflicted by host immunity. Improving our understanding of these defense pathways can reveal vulnerable points in Mtb pathogenesis. In this study, we combined genetic, structural, computational, biochemical, and biophysical approaches to identify a novel enzyme class represented by Rv2466c. We show that Rv2466c is a mycothiol-dependent nitroreductase of Mtb and can reduce the nitro group of a novel mycobactericidal compound using mycothiol as a cofactor. In addition to its function as a nitroreductase, Rv2466c confers partial protection to menadione stress.

Abstract P1-10-02: A phase II study of copper-depletion using tetrathiomolybdate in patients with breast cancer at high risk for recurrence: Updated results

Background: Metals have emerged as a viable therapeutic target for a new generation of anti-cancer and anti-metastatic agents. Copper, an essential trace element, serves as an important catalytic cofactor in several biological functions and has emerged as an essential factor in carcinogenesis. Among other elements, bone marrow derived VEGFR2+ endothelial progenitor cells (EPCs) and copper-dependent lysyl oxidase (LOX) are key elements in tumor progression. We hypothesized tetrathiomolybdate (TM)-associated copper depletion (CD) inhibits tumor metastases by reducing the number of EPCs and other copper dependent processes in the pre-metastatic niche. These results are an update of our previously reported study (Chan N, Willis A, Kornhauser N et al. Influencing the Tumor Microenvironment: Phase 2 Study of Copper Depletion with Tetrathiomolybdate in High Risk Breast Cancer and Preclinical Models of Lung Metastases. Clin Cancer Res. October 21, 2016) with longer follow-up.

Methods: A single arm phase II study of breast cancer (BC) patients (pts) at high risk for recurrence, defined as node+ triple negative (TNBC), stage 3 and 4 with no evidence of disease (NED) were enrolled on a trial of CD with TM. TM was given to maintain ceruloplasmin (Cp) levels between 8-16 mg/dl for two years with an extension phase or until relapse. The primary endpoint was a change in EPCs measured by flow cytometry before and during treatment. Secondary endpoints included tolerability, safety, PFS and LOXL-2 levels.

Results: Seventy-five pts received 2778 cycles of TM on the primary and extension study. The primary study treatment duration was 24 cycles (each cycle is 28 days) plus an extension phase. The median age is 51 years (range 29-66). Forty-five pts have stage 2/3 BC and 30 with stage 4 NED. Forty-eight percent of pts are TNBC and 40% of pts are stage 4 NED. Median Cp levels were monitored with each cycle. A decrease from 28 to 16 (p<0.0001) was seen after one cycle. Interestingly, TNBC pts seemed to have a greater decrease from 23.5 to 13 after one cycle. TM was well tolerated with grade 3/4 toxicities including: reversible neutropenia (2.3%), febrile neutropenia (0.04%), fatigue (0.2%). Five-year analysis showed a decrease in EPC's (p=0.004) and LOXL-2 (p<0.001). At a median follow-up of 7.1 years, the EFS for 75 pts is 71.4%. The EFS for 36 pts with TNBC is 71.7%. EFS for stage 2/3 TNBC is 83% and for stage IV TNBC is 59.3%.

Conclusions: TM is safe, well tolerated and appears to affect multiple components of the tumor microenvironment that have been identified in pre-clinical models as important for progression. Ongoing studies in banked specimens are underway to further delineate its effect on copper dependent processes necessary for metastases. Randomized trials are warranted, especially in patients who are at high risk for relapse such as those with TNBC.

Citation Format: Sahota S, Willis A, Kornhauser N, Ward M, Cobham M, Cigler T, Moore A, Andreopoulou E, Fitzpatrick V, Schneider S, Prima N, Wiener A, Ko D, De Laurentiis A, Warren JD, Rubinchik A, Mittal V, Vahdat LT. A phase II study of copper-depletion using tetrathiomolybdate in patients with breast cancer at high risk for recurrence: Updated results [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-10-02.

[18F]RPS-544: A PET tracer for imaging the chemokine receptor CXCR4

INTRODUCTION

CXCR4 specific [¹⁸F]-labeled positron emission tomography (PET) imaging agents are needed which would enable general distribution of the radiotracer for clinical investigation. We sought to synthesize, radiolabel and evaluate [¹⁸F]RPS-544, a novel non-peptide CXCR4 antagonist as a CXCR4 specific probe. We compared [¹⁸F]RPS-544 with the previously published [¹⁸F]-3 ([¹⁸F]RPS-510 in this paper) in a bi-lateral tumor model of differential CXCR4 expression for its ability to selectively target CXCR4 expression.

METHODS

Radiolabeling of [¹⁸F]RPS-544 and [¹⁸F]RPS-510 was performed by aromatic substitution on a 6-nitropyridyl group using no-carrier-added [¹⁸F]fluoride under basic conditions. ¹⁸F incorporation was determined by radioHPLC. Semi-preparative HPLC was used to purify the final product prior to reformulation. Imaging and biodistribution was performed in nude mice with bilateral PC3 (CXCR4+ and WT) xenograft tumors at 1, 2 and 4 h post injection.

RESULTS

RPS-544 bound CXCR4 with an IC50 of 4.9 ± 0.3 nM. [¹⁸F]RPS-544 showed preferential uptake in CXCR4+ tumors, with a CXCR4/WT ratio of 3.3 ± 1.3 at 1 h p.i. and 2.3 ± 0.5 at 2 h p.i. Maximum uptake in the CXCR4+ tumors was 3.4 ± 1.2%ID/g at 1 h p.i., significantly greater (p = 0.003) than the uptake in the WT tumor. Tumor/blood ratios were 2.5 ± 0.4 and 3.6 ± 0.3 at 1 and 2 h p.i. Tumor/muscle ratios were >4 at all time-points. Tumor/lung ratios were >2 at 1 h and 2 h p.i. Substantial uptake was observed in the liver (15-25%ID/g), kidneys (25-35%ID/g), the small intestine (1-7%ID/g) and the large intestine (1-12%ID/g). Blood concentrations varied over time (0.5-2%ID/g). All other organs showed uptake of <1%ID/g at all time points studied with clearance profiles similar to blood clearance.

CONCLUSIONS

Here we present, to the best of our knowledge, the first high affinity [18F]-labeled tracer, suitable for in vivo PET imaging of CXCR4. [18F]RPS-544 displayed high affinity for CXCR4 and good tumor uptake with a maximum uptake at 1 h p.i.. CXCR4 dependent uptake was demonstrated using bilateral tumors with differential CXCR4 expression as well as pharmacological blockade using the known CXCR4 antagonist, AMD-3100. Tissue contrast as judged by tumor to normal tissue ratios was positive in several key tissues. The structural and pharmacological similarities between [18F]RPS-544 and the approved drug AMD-3465, combined with the ease of synthesis and high molar activity (>185 GBq/μmol) achieved during radiosynthesis could lead to accelerated translation into the clinic.

Identification of a nucleoside analog active against adenosine kinase-expressing plasma cell malignancies

Primary effusion lymphoma (PEL) is a largely incurable malignancy of B cell origin with plasmacytic differentiation. Here, we report the identification of a highly effective inhibitor of PEL. This compound, 6-ethylthioinosine (6-ETI), is a nucleoside analog with toxicity to PEL in vitro and in vivo, but not to other lymphoma cell lines tested. We developed and performed resistome analysis, an unbiased approach based on RNA sequencing of resistant subclones, to discover the molecular mechanisms of sensitivity. We found different adenosine kinase-inactivating (ADK-inactivating) alterations in all resistant clones and determined that ADK is required to phosphorylate and activate 6-ETI. Further, we observed that 6-ETI induces ATP depletion and cell death accompanied by S phase arrest and DNA damage only in ADK-expressing cells. Immunohistochemistry for ADK served as a biomarker approach to identify 6-ETI-sensitive tumors, which we documented for other lymphoid malignancies with plasmacytic features. Notably, multiple myeloma (MM) expresses high levels of ADK, and 6-ETI was toxic to MM cell lines and primary specimens and had a robust antitumor effect in a disseminated MM mouse model. Several nucleoside analogs are effective in treating leukemias and T cell lymphomas, and 6-ETI may fill this niche for the treatment of PEL, plasmablastic lymphoma, MM, and other ADK-expressing cancers.

Influencing the Tumor Microenvironment: A Phase II Study of Copper Depletion Using Tetrathiomolybdate in Patients with Breast Cancer at High Risk for Recurrence and in Preclinical Models of Lung Metastases

PURPOSE

Bone marrow-derived progenitor cells, including VEGFR2⁺ endothelial progenitor cells (EPCs) and copper-dependent pathways, model the tumor microenvironment. We hypothesized that copper depletion using tetrathiomolybdate would reduce EPCs in high risk for patients with breast cancer who have relapsed. We investigated the effect of tetrathiomolybdate on the tumor microenvironment in preclinical models.

EXPERIMENTAL DESIGN

Patients with stage II triple-negative breast cancer (TNBC), stage III and stage IV without any evidence of disease (NED), received oral tetrathiomolybdate to maintain ceruloplasmin (Cp) between 8 and 17 mg/dL for 2 years or until relapse. Endpoints were effect on EPCs and other biomarkers, safety, event-free (EFS), and overall survival (OS). For laboratory studies, MDA-LM2-luciferase cells were implanted into CB17-SCID mice and treated with tetrathiomolybdate or water. Tumor progression was quantified by bioluminescence imaging (BLI), copper depletion status by Cp oxidase levels, lysyl oxidase (LOX) activity by ELISA, and collagen deposition.

RESULTS

Seventy-five patients enrolled; 51 patients completed 2 years (1,396 cycles). Most common grade 3/4 toxicity was neutropenia (3.7%). Lower Cp levels correlated with reduced EPCs (P = 0.002) and LOXL-2 (P < 0.001). Two-year EFS for patients with stage II-III and stage IV NED was 91% and 67%, respectively. For patients with TNBC, EFS was 90% (adjuvant patients) and 69% (stage IV NED patients) at a median follow-up of 6.3 years, respectively. In preclinical models, tetrathiomolybdate decreased metastases to lungs (P = 0.04), LOX activity (P = 0.03), and collagen crosslinking (P = 0.012).

CONCLUSIONS

Tetrathiomolybdate is safe, well tolerated, and affects copper-dependent components of the tumor microenvironment. Biomarker-driven clinical trials in high risk for patients with recurrent breast cancer are warranted. Clin Cancer Res; 23(3); 666-76. ©2016 AACR.

Abstract LB-349: Copper depletion as a strategy to affect the tumor microenvironment in breast cancer patients at high risk of relapse and in triple negative preclinical models of breast cancer: Updated results of a phase II study of tetrathiomolybdate (TM) in breast cancer (BC) patients (pts) at high risk for recurrence

Background: The pre-metastatic niche mobilizes copper to assist in conditioning the tumor microenvironment facilitating tumor progression. This includes bone marrow derived VEGFR2+ endothelial progenitor cells (EPCs) and copper-dependent lysyl oxidase (LOX). We hypothesized that TM-associated CD would reduce EPCs and other copper dependent processes in the pre-metastatic niche in BC pts.

Methods: Stage 2 triple negative BC, Stage 3 and stage 4 without any evidence of disease, (NED) BC pts, received oral TM to maintain ceruloplasmin (Cp) between 8-17mg/dL for 2 years or until relapse. Endpoints included change in EPCs, safety, disease-free (DFS) and overall survival (OS) and effect on biomarkers. Laboratory studies: MDA-LM2-luciferase cells were implanted into CB17-SCID mice, and treated with TM or water. Tumor progression was quantified by bioluminescence imaging (BLI), CD status by Cp oxidase levels, lysyl oxidase (LOXL2) activity by ELISA, and collagen deposition by Picrosirius Red staining and Second Harmonic Generation (SHG) imaging analysis.

Results: 75 pts (45 stage 2/3 BC, 30 stage 4 NED) received over 2400 cycles of TM on the primary and extension studies. Median age: 51 yrs (range 29-66). Of the 75 pts, 48% had TNBC, 40% were stage 4 NED. Median Cp level decreased from 28 at baseline to 15.5 (p&lt;0.0001) after one cycle. Grade 3/4 toxicities included reversible neutropenia (2.3%), anemia (0.04%), leukopenia (1.2%) and fatigue (0.09%). CD was associated with a decrease in EPCs (p = 0.0014) and serum LOX (p&lt;0.001). At a median follow-up of 5.9 years, the PFS for all 75 pts is 72%, including a PFS of 90% for all stage 2/3 pts with TNBC. The overall survival is 84%. Relapse after two years is a rare event. In pre-clinical models, TM had no effects on the primary tumor, but decreased secondary lung metastases (p = 0.04) as seen by BLI. Western blots demonstrated decreased LOX in the pre-metastatic lungs vs controls (p = 0.03), and IHC showed reduced collagen cross-linking by image J (p = 0.01). SHG analysis showed reduced collagen fiber length.

Conclusions: TM is safe, well tolerated and appears to affect multiple copper dependent biologic processes in the tumor microenvironment known to be important for tumor progression, most striking in TNBC. Randomized trials in a high risk for relapse population are warranted.

Citation Format: Eleni Nackos, Sharrell Lee, Amy Willis, Naomi Kornhauser, Maureen Ward, Marta Cobham, Tessa Cigler, Anne Moore, Veronica Fitzpatrick, Sarah Schneider, Alysia Wiener, Jessica Guillaume-Abraham, Bo Ri Seo, J David Warren, Anna Rubinchik, Claudia Fischbach, Vivek Mittal, Linda Vahdat. Copper depletion as a strategy to affect the tumor microenvironment in breast cancer patients at high risk of relapse and in triple negative preclinical models of breast cancer: Updated results of a phase II study of tetrathiomolybdate (TM) in breast cancer (BC) patients (pts) at high risk for recurrence. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr LB-349.

Abstract 1074: A novel synthetic biotinylated microRNA-1207-3p duplex targets the 3’UTR of FNDC1 and inhibits proliferation and migration of prostate cancer cells

Prostate cancer (PCa) is the second leading cause of cancer death in US men and the dysregulation of microRNAs contributes to its development. Recently we discovered that miR-1207-3p, encoded at the PVT1 gene locus on the 8q24 human chromosomal region, is significantly underexpressed in PCa cell lines and directly targets the 3’ untranslated region (UTR) of Fibronectin type III domain containing 1 (FNDC1). Moreover, using an oligonucleotide mimic and inhibitor of miR-1207-3p, we established that miR-1207-3p regulates the proliferation and migration of prostate epithelial cells. To discover the molecular targets of miR-1207-3p unbiasedly, a RNA pull-down assay needed to be performed, yet no biotinylated miR-1207-3p mimic was commercially available. Consequently, we designed and synthesized a novel synthetic biotinylated miR-1207-3p duplex, and a novel synthetic biotinylated scramble duplex (patents pending). Prior to using the novel duplexes for molecular target discovery, we compared their effects to that of the previously used commercially available miR-1207-3p mimic and scramble control on the 3’UTR of FNDC1, and PCa cell proliferation and migration. Effects were assessed using the E006AA mildly tumorigenic PCa cell line and its aggressively tumorigenic derivative, E006AA-hT. Using these two PCa cell lines transiently transfected with 3’UTR of FNDC1-containing Luc-Pair™ Duo-Luciferase expressing vector, we found that the biotinylated miR-1207-3p duplex directly targets the 3’UTR of FNDC1 in comparison to the biotinylated scramble duplex. MTT assays revealed that the biotinylated miR-1207-3p duplex significantly decreased the proliferation of both PCa cell lines in comparison to the control biotinylated scramble duplex. Interestingly, the biotinylated miR-1207-3p duplex further decreased the proliferation of the aggressively tumorigenic E006AA-hT by an extra 25%, compared to the decrease in the proliferation of the indolent E006AA, suggesting that it may have some selectivity for aggressive PCa cells. Wound healing assays revealed that the biotinylated miR-1207-3p duplex significantly inhibited migration of both PCa cell lines by about 60% in comparison to the control biotinylated scramble duplex. Notably, the mimic of miR-1207-3p had no effects on the proliferation or migration of these cell lines when compared to scramble controls. In conclusion, to our knowledge, we have designed and synthesized the first synthetic biotinylated miR-1207-3p duplex. Importantly, unlike the mimic of miR-1207-3p, this novel synthetic biotinylated miR-1207-3p duplex significantly inhibits proliferation and migration of PCa cells including those aggressively tumorigenic. Consequently, the novel synthetic biotinylated miR-1207-3p duplex is a useful new tool for miR-1207-3p molecular target discovery, and potentially as a novel therapeutic strategy in PCa.

Citation Format: Dibash K. Das, J David Warren, Olorunseun O. Ogunwobi. A novel synthetic biotinylated microRNA-1207-3p duplex targets the 3’UTR of FNDC1 and inhibits proliferation and migration of prostate cancer cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1074.

Abstract P3-02-02: Targeting the tumor microenvironment: A phase II study of copper-depletion using tetrathiomolybdate (TM) in patients (pts) with breast cancer (BC) at high risk for recurrence

Background: Bone marrow derived VEGFR2+ endothelial progenitor cells (EPCs) and copper-dependent pathways, including lysyl oxidase (LOX), are critical components to remodeling the tumor microenvironment and establishing the pre-metastatic niche. In preclinical models, it has been well established that copper depletion (CD) inhibits tumor progression. We hypothesized that TM-associated CD would reduce EPCs and other copper dependent processes in the pre-metastatic niche in BC pts at high risk for relapse. We investigated the relationship between CD and its effect on EPCs and other components of the tumor microenvironment including LOX, an enzyme critical for cross-linkage of collagen and priming the pre-metastatic niche.

Methods: In this single arm, phase II study, BC pts at high risk for recurrence, defined as node+ triple negative (TN), stage 3 and 4 with no evidence of disease (NED) were enrolled on a trial of CD with TM. Pts received oral TM to maintain ceruloplasmin (Cp) between 5-17 mg/dl for 2 years on the primary study. The primary endpoint was change in EPCs measured by flow cytometry before and during treatment with TM. Secondary endpoints included tolerability, safety and effect of copper depletion on other markers including LOX, quantified by ELISA.

Results: We enrolled 75 pts. The study treatment duration was 24 cycles (each cycle is 28 days). Over 2200 cycles have been administered. The median age is 51 (range 29-66). 45 pts have Stage 2/3 BC and 30 are Stage 4 NED. TNBC pts represent 48%, and 40% of pts are Stage 4 NED. Median Cp level decreased from 28 at baseline to 15.5 (p&lt;0.0001) after one cycle. Copper depletion was most efficient in TNBC, with 91% achieving a target CP within 4 weeks. TM was well tolerated and the only grade 3/4 toxicities were reversible neutropenia (3.2%) and anemia (0.0005%). CD was associated with a significant decrease in EPCs (p=0.0014) and LOX (p&lt;0.001). At a median follow-up of 5.4 years, the PFS for all 75 pts from the start of TM treatment was 71%, including a PFS of 90% for all stage 2/3 pts with TNBC. The overall survival of all patients enrolled in the trial is 86%. Relapse after two years is a rare event. Conclusions: TM is safe, well tolerated and appears to affect multiple copper dependent biologic processes in the tumor microenvironment known to be important for tumor progression. This seems to be most striking in TNBC. We believe, further phase III trials in a high risk for relapse population are warranted.

Citation Format: Nackos E, Willis A, Kornhauser N, Ward M, Andreopoulou E, Cigler T, Moore A, Fitzpatrick V, Cobham M, Schneider S, Wiener A, Guillaume-Abraham J, Warren JD, Rubinchik A, Lane M, Mittal V, Vahdat L. Targeting the tumor microenvironment: A phase II study of copper-depletion using tetrathiomolybdate (TM) in patients (pts) with breast cancer (BC) at high risk for recurrence. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-02-02.

USING FLORBETAPIR PET TO INCREASE DIAGNOSTIC CERTAINTY IN ATYPICAL DEMENTIAS

Amyloid PET or CSF can be used to determine Alzheimer pathology in vivo. Few studies have assessed the additional value of amyloid imaging where CSF results are equivocal. We recruited 20 cognitive patients (65.5+/–7.6 y) with MRI, neuropsychology, and CSF Aβ1–42 and tau measured during their diagnostic assessment. Individuals were selected to have a range of CSF results; ten had amnestic and ten non-amnestic presentations. Following the investigations, the treating neurologist gave a diagnosis (AD or non-AD). Four controls (63+/–7.0y) also had CSF examination. All subjects had Florbetapir PET imaging, reported as positive/negative. The clinicians were given the PET results and asked to review their diagnoses. Eighteen patients had positive Florbetapir scans; two patients and all controls were Florbetapir negative. Following initial investigations, thirteen patients were diagnosed with AD, and seven with non-AD pathology. Providing the Florbetapir result led to a change in diagnosis in seven patients, five of whom had atypical phenotypes. For all seven the CSF results were close to or in a “grey” area, where results overlapped for positive and negative PET scans. Even in individuals with CSF measures of Aβ1–42, and tau, Florbetapir PET imaging may have diagnostic utility, particularly in atypical cases and/or equivocal CSF results.

Abstract 4496: Genomics-based resistome analysis revealed endogenous adenosine kinase levels as a chief determinant of specificity for a novel nucleoside analog lymphoma inhibitor

We used KSHV-infected primary effusion lymphoma (PEL) cells as a model to search for novel drugs through a combination of screening and genomic approaches. We discovered 6-ethylthioinosine (6-ETI), a nucleoside analog, as a highly effective and selective inhibitor of PEL. This compound induces necrosis accompanied by S-phase arrest without affecting known oncogenic viral proteins. To understand the selectivity towards PEL, we performed unbiased genomic analysis of 6-ETI-resistant subclones using RNASeq, which revealed that 6-ETI is activated through phosphorylation by cellular adenosine kinase (ADK). PEL cell lines have higher basal levels of ADK than resistant lymphoma cell lines, and resistant lymphoma cell lines could be sensitized by cell crowding-induced ADK upregulation. Finally, 6-ETI was shown to be highly efficacious against incipient and established tumors in a mouse model of PEL, with no apparent toxicity. Thus, we have successfully used RNASeq-based “resistome” analysis to identify the mechanism of specificity for a new and preclinically effective nucleoside analog.

Citation Format: Utthara Nayar, Jonathan Reichel, Jouliana Sadek, Denise Hernandez-Hopkins, Gunkut Akar, Hufeng Zhou, Michelle A. Sahai, Peter Barelli, Ilaria Guasparri, Jennifer Totonchy, Duane Hassane, Shizuko Sei, Robert H. Shoemaker, J. David Warren, Olivier Elemento, Kenneth M. Kaye, Ethel Cesarman. Genomics-based resistome analysis revealed endogenous adenosine kinase levels as a chief determinant of specificity for a novel nucleoside analog lymphoma inhibitor. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4496. doi:10.1158/1538-7445.AM2015-4496

Targeting mitochondrial cardiolipin and the cytochrome c/cardiolipin complex to promote electron transport and optimize mitochondrial ATP synthesis

BACKGROUND AND PURPOSE

Cardiolipin plays an important role in mitochondrial respiration and cardiolipin peroxidation is associated with age-related diseases. Hydrophobic interactions between cytochrome c and cardiolipin converts cytochrome c from an electron carrier to a peroxidase. In addition to cardiolipin peroxidation, this impedes electron flux and inhibits mitochondrial ATP synthesis. SS-31 (D-Arg-dimethylTyr-Lys-Phe-NH2 ) selectively binds to cardiolipin and inhibits cytochrome c peroxidase activity. Here, we examined whether SS-31 also protected the electron carrier function of cytochrome c.

EXPERIMENTAL APPROACH

Interactions of SS-31 with cardiolipin were studied using liposomes and bicelles containing phosphatidylcholine alone or with cardiolipin. Structural interactions were assessed by fluorescence spectroscopy, turbidity and nuclear magnetic resonance. Effects of cardiolipin on electron transfer kinetics of cytochrome c were determined by cytochrome c reduction in vitro and oxygen consumption using mitoplasts, frozen and fresh mitochondria.

KEY RESULTS

SS-31 interacted only with liposomes and bicelles containing cardiolipin in about 1:1 ratio. NMR studies demonstrated that the aromatic residues of SS-31 penetrated deep into cardiolipin-containing bilayers. SS-31 restored cytochrome c reduction and mitochondrial oxygen consumption in the presence of added cardiolipin. In fresh mitochondria, SS-31 increased state 3 respiration and efficiency of ATP synthesis.

CONCLUSIONS AND IMPLICATIONS

SS-31 selectively targeted cardiolipin and modulated its interaction with cytochrome c. SS-31 inhibited the cytochrome c/cardiolipin complex peroxidase activity while protecting its ability to serve as an electron carrier, thus optimizing mitochondrial electron transport and ATP synthesis. This novel class of cardiolipin therapeutics has the potential to restore mitochondrial bioenergetics for treatment of numerous age-related diseases.

Biomarkers in dementia: clinical utility and new directions

Imaging, cerebrospinal fluid (CSF) and blood-based biomarkers have the potential to improve the accuracy by which specific causes of dementia can be diagnosed in vivo, provide insights into the underlying pathophysiology, and may be used as inclusion criteria and outcome measures for clinical trials. While a number of imaging and CSF biomarkers are currently used for each of these purposes, this is an evolving field, with numerous potential biomarkers in varying stages of research and development. We review the currently available biomarkers for the three most common forms of neurodegenerative dementia, and give an overview of research techniques that may in due course make their way into the clinic.

Oxathiazolones Selectively Inhibit the Human Immunoproteasome over the Constitutive Proteasome

Selective inhibitors for the human immunoproteasome LMP7 (β5i) subunit over the constitutive proteasome hold promise for the treatment of autoimmune and inflammatory diseases and hematologic malignancies. Here we report that oxathiazolones inhibit the immunoproteasome β5i with up to 4700-fold selectivity over the constitutive proteasome, are cell permeable, and inhibit proteasomes inside cells.

Presymptomatic studies in genetic frontotemporal dementia

Approximately 20% of patients with the neurodegenerative disorder frontotemporal dementia (FTD) have an autosomal dominant pattern of inheritance. Genetic FTD is caused by mutations in three genes in most cases (progranulin, microtubule-associated protein tau and chromosome 9 open reading frame 72) although a number of other genes are rare causes. Studies of other neurodegenerative diseases have shown imaging and biomarker evidence of disease onset many years prior to the development of symptoms. Similar studies in genetic FTD are now revealing evidence of a series of presymptomatic changes, initially in plasma biomarkers followed by MR imaging abnormalities of functional and structural connectivity and then grey matter atrophy. Lastly, neuropsychometric tests become abnormal in proximity to the onset of symptoms. Such studies have been relatively small until now but research centres with an expertise in genetic FTD are now forming consortia such as the Genetic Frontotemporal Dementia Initiative (GenFI) to create larger cohorts that can form the basis of future clinical trials.

Whole cell screen for inhibitors of pH homeostasis in Mycobacterium tuberculosis

Bacterial pathogens like Mycobacterium tuberculosis (Mtb) encounter acidic microenvironments in the host and must maintain their acid-base homeostasis to survive. A genetic screen identified two Mtb strains that cannot control intrabacterial pH (pH_IB) in an acidic environment; infection with either strain led to severe attenuation in mice. To search for additional proteins that Mtb requires to survive at low pH, we introduced a whole-cell screen for compounds that disrupt pH_IB, along with counter-screens that identify ionophores and membrane perturbors. Application of these methods to a natural product library identified four compounds of interest, one of which may inhibit novel pathway(s). This approach yields compounds that may lead to the identification of pathways that allow Mtb to survive in acidic environments, a setting in which Mtb is resistant to most of the drugs currently used to treat tuberculosis.

The mitochondrial-targeted compound SS-31 re-energizes ischemic mitochondria by interacting with cardiolipin

Ischemia causes AKI as a result of ATP depletion, and rapid recovery of ATP on reperfusion is important to minimize tissue damage. ATP recovery is often delayed, however, because ischemia destroys the mitochondrial cristae membranes required for mitochondrial ATP synthesis. The mitochondria-targeted compound SS-31 accelerates ATP recovery after ischemia and reduces AKI, but its mechanism of action remains unclear. Here, we used a polarity-sensitive fluorescent analog of SS-31 to demonstrate that SS-31 binds with high affinity to cardiolipin, an anionic phospholipid expressed on the inner mitochondrial membrane that is required for cristae formation. In addition, the SS-31/cardiolipin complex inhibited cytochrome c peroxidase activity, which catalyzes cardiolipin peroxidation and results in mitochondrial damage during ischemia, by protecting its heme iron. Pretreatment of rats with SS-31 protected cristae membranes during renal ischemia and prevented mitochondrial swelling. Prompt recovery of ATP on reperfusion led to rapid repair of ATP-dependent processes, such as restoration of the actin cytoskeleton and cell polarity. Rapid recovery of ATP also inhibited apoptosis, protected tubular barrier function, and mitigated renal dysfunction. In conclusion, SS-31, which is currently in clinical trials for ischemia-reperfusion injury, protects mitochondrial cristae by interacting with cardiolipin on the inner mitochondrial membrane.

EFNS-ENS Guidelines on the diagnosis and management of disorders associated with dementia

BACKGROUND AND OBJECTIVES

The last version of the EFNS dementia guidelines is from 2007. In 2010, the revised guidelines for Alzheimer's disease (AD) were published. The current guidelines involve the revision of the dementia syndromes outside of AD, notably vascular cognitive impairment, frontotemporal lobar degeneration, dementia with Lewy bodies, corticobasal syndrome, progressive supranuclear palsy, Parkinson's disease dementia, Huntington's disease, prion diseases, normal-pressure hydrocephalus, limbic encephalitis and other toxic and metabolic disorders. The aim is to present a peer-reviewed evidence-based statement for the guidance of practice for clinical neurologists, geriatricians, psychiatrists and other specialist physicians responsible for the care of patients with dementing disorders. It represents a statement of minimum desirable standards for practice guidance.

METHODS

The task force working group reviewed evidence from original research articles, meta-analyses and systematic reviews, published by June 2011. The evidence was classified (I, II, III, IV) and consensus recommendations graded (A, B, or C) according to the EFNS guidance. Where there was a lack of evidence, but clear consensus, good practice points were provided.

RESULTS AND CONCLUSIONS

New recommendations and good practice points are made for clinical diagnosis, blood tests, neuropsychology, neuroimaging, electroencephalography, cerebrospinal fluid (CSF) analysis, genetic testing, disclosure of diagnosis, treatment of behavioural and psychological symptoms in dementia, legal issues, counselling and support for caregivers. All recommendations were revised as compared with the previous EFNS guidelines. The specialist neurologist together with primary care physicians play an important role in the assessment, interpretation and treatment of symptoms, disability and needs of dementia patients.

Tetrathiomolybdate-associated copper depletion decreases circulating endothelial progenitor cells in women with breast cancer at high risk of relapse

BACKGROUND

Bone marrow-derived endothelial progenitor cells (EPCs) are critical for metastatic progression. This study explores the effect of tetrathiomolybdate (TM), an anti-angiogenic copper chelator, on EPCs in patients at high risk for breast cancer recurrence.

PATIENTS AND METHODS

This phase 2 study enrolled breast cancer patients with stage 3 and stage 4 without evidence of disease (NED), and stage 2 if triple-negative. TM 100 mg orally was administered to maintain ceruloplasmin <17 mg/dl for 2 years or until relapse. The primary end point was change in EPCs.

RESULTS

Forty patients (28 stage 2/3, 12 stage 4 NED) were enrolled. Seventy-five percent patients achieved the copper depletion target by 1 month. Ninety-one percent of triple-negative patients copper-depleted compared with 41% luminal subtypes. In copper-depleted patients only, there was a significant reduction in EPCs/ml by 27 (P = 0.04). Six patients relapsed while on study, of which only one patient had EPCs maintained below baseline. The 10-month relapse-free survival was 85.0% (95% CI 74.6%-96.8%). Only grade 3/4 toxicity was hematologic: neutropenia (3.1% of cycles), febrile neutropenia (0.2%), and anemia (0.2%).

CONCLUSIONS

TM is safe and appears to maintain EPCs below baseline in copper-depleted patients. TM may promote tumor dormancy and ultimately prevent relapse.

On the Mechanisms of Cyanine Fluorophore Photostabilization

Cyanine fluorophores exhibit greatly improved photostability when covalently linked to stabilizers, such as cyclooctatetraene (COT), nitrobenzyl alcohol (NBA) or Trolox. However, the mechanism by which photostabilization is mediated has yet to be determined. Here we present spectroscopic evidence that COT, when covalently linked to Cy5, substantially reduces the lifetime of the Cy5 triplet state, and that the degree of triplet state quenching correlates with enhancements in photostability observed in single-molecule fluorescence measurements. By contrast, NBA and Trolox did not quench the Cy5 triplet state under our conditions suggesting that their mechanism of photostabilization is different from COT and does not target the fluorophore triplet state directly. These findings provide insights into the mechanisms of fluorophore photostabilization that may lead to improved fluorophore designs for biological imaging applications.

Discovery and biological characterization of 1-(1H-indol-3-yl)-9H-pyrido[3,4-b]indole as an aryl hydrocarbon receptor activator generated by photoactivation of tryptophan by sunlight

Activation of the aryl hydrocarbon receptor (AHR) by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is required for AHR dependent transcriptional activation and TCDD toxicity. We previously reported that aqueous tryptophan exposed to sunlight through window glass (aTRP) contains multiple photoproducts, including the well characterized 6-formylindolo[3,2-b]carbazole (FICZ), capable of activating the AHR and inducing CYP1A and CYP1A-mediated enzyme activities. We report here the isolation from aTRP and chemical characterization and synthesis of 1-(1H-indol-3-yl)-9H-pyrido[3,4-b]indole (IPI), a compound previously identified as a natural product of marine ascidia and now shown to be a TRP photoproduct with AHR-inducing properties. IPI, FICZ and TCDD produced equieffective induction of CYP1A-mediated 7-ethoxyresorufin deethylase (EROD) activity in chick embryo primary hepatocytes and mammalian Hepa1c1c7 cells. EROD induction by IPI was markedly curtailed in AHR-defective c35 cells, supporting the AHR dependence of the IPI response. Although IPI had a higher EC(50) for EROD induction than FICZ, the much larger amount of IPI than FICZ in aTRP makes IPI a prominent contributor to EROD induction in aTRP. IPI was detected in TRP-containing culture medium under ambient laboratory conditions but not in TRP-free medium, consistent with its production from TRP. Cotreatment of hepatocytes with submaximal EROD-inducing doses of IPI and FICZ or TCDD produced additive increases in EROD without synergistic or inhibitory interactions. IPI and FICZ were readily metabolized by cultured hepatocytes. In addition to increasing CYP1A4 mRNA and EROD, IPI and FICZ decreased hepatocyte phosphoenolpyruvate carboxykinase mRNA expression and glucose output, biological effects associated with TCDD metabolic dysregulation. The findings underscore a role for sunlight in generating AHR-activating bioactive molecules.

On the chemical mechanism of succinic semialdehyde dehydrogenase (GabD1) from Mycobacterium tuberculosis

Succinic semialdehyde dehydrogenases (SSADHs) are ubiquitous enzymes that catalyze the NAD(P)+-coupled oxidation of succinic semialdehyde (SSA) to succinate, the last step of the γ-aminobutyrate shunt. Mycobacterium tuberculosis encodes two paralogous SSADHs (gabD1 and gabD2). Here, we describe the first mechanistic characterization of GabD1, using steady-state kinetics, pH-rate profiles, ¹H NMR, and kinetic isotope effects. Our results confirmed SSA and NADP+ as substrates and demonstrated that a divalent metal, such as Mg²+, linearizes the time course. pH-rate studies failed to identify any ionizable groups with pK(a) between 5.5 and 10 involved in substrate binding or rate-limiting chemistry. Primary deuterium, solvent and multiple kinetic isotope effects revealed that nucleophilic addition to SSA is very fast, followed by a modestly rate-limiting hydride transfer and fast thioester hydrolysis. Proton inventory studies revealed that a single proton is associated with the solvent-sensitive rate-limiting step. Together, these results suggest that product dissociation and/or conformational changes linked to it are rate-limiting. Using structural information for the human homolog enzyme and ¹H NMR, we further established that nucleophilic attack takes place at the Si face of SSA, generating a thiohemiacetal with S stereochemistry. Deuteride transfer to the Pro-R position in NADP+ generates the thioester intermediate and [4A-²H, 4B-¹H] NADPH. A chemical mechanism based on these data and the structural information available is proposed.

Opsin is a phospholipid flippase

Polar lipids must flip-flop rapidly across biological membranes to sustain cellular life [1, 2], but flipping is energetically costly [3] and its intrinsic rate is low. To overcome this problem, cells have membrane proteins that function as lipid transporters (flippases) to accelerate flipping to a physiologically relevant rate. Flippases that operate at the plasma membrane of eukaryotes, coupling ATP hydrolysis to unidirectional lipid flipping, have been defined at a molecular level [2]. On the other hand, ATP-independent bidirectional flippases that translocate lipids in biogenic compartments, e.g., the endoplasmic reticulum, and specialized membranes, e.g., photoreceptor discs [4, 5], have not been identified even though their activity has been recognized for more than 30 years [1]. Here, we demonstrate that opsin is the ATP-independent phospholipid flippase of photoreceptor discs. We show that reconstitution of opsin into large unilamellar vesicles promotes rapid (τ<10 s) flipping of phospholipid probes across the vesicle membrane. This is the first molecular identification of an ATP-independent phospholipid flippase in any system. It reveals an unexpected activity for opsin and, in conjunction with recently available structural information on this G protein-coupled receptor [6, 7], significantly advances our understanding of the mechanism of ATP-independent lipid flip-flop.

Measuring disease progression in frontotemporal lobar degeneration: a clinical and MRI study

OBJECTIVES

There is currently much interest in biomarkers of disease activity in frontotemporal lobar degeneration (FTLD). We assessed MRI and behavioral measures of progression in a longitudinal FTLD cohort.

METHODS

Thirty-two patients with FTLD (11 behavioral variant frontotemporal dementia [bvFTD], 11 semantic dementia [SemD], 10 progressive nonfluent aphasia [PNFA]) and 24 age-matched healthy controls were assessed using volumetric brain MRI and standard behavioral measures (Mini-Mental State Examination, Frontal Assessment Battery, Clinical Dementia Rating Scale, Neuropsychiatric Inventory with Caregiver Distress scale) at baseline and 1 year later. A semi-automated image registration protocol was used to calculate annualized rates of brain atrophy (brain boundary shift integral [BBSI]) and ventricular expansion (ventricular boundary shift integral [VBSI]). Associations between these rates and changes in behavioral indices were investigated.

RESULTS

Rates of whole brain atrophy were greater in the entire FTLD cohort and in each subgroup compared with controls (all p < or = 0.004). Rates of ventricular expansion were greater in the entire cohort (p < 0.001) and the SemD (p = 0.002) and PNFA (p = 0.05) subgroups compared with controls. Changes in Mini-Mental State Examination, Frontal Assessment Battery, and Clinical Dementia Rating Scale scores were associated with MRI measures of progression, though not uniformly across FTLD subgroups. Both BBSI and VBSI yielded feasible sample size estimates for detecting meaningful treatment effects in SemD and PNFA language subgroups. Sample sizes were substantially larger using MRI biomarkers for the bvFTD subgroup, and using behavioral biomarkers in general.

CONCLUSIONS

Semi-automated MRI atrophy measures are potentially useful objective biomarkers of progression in frontotemporal lobar degeneration (FTLD); however, careful stratification of FTLD subtypes will be important in future clinical trials of disease-modifying therapies.

Triazaspirodimethoxybenzoyls as selective inhibitors of mycobacterial lipoamide dehydrogenase

Mycobacterium tuberculosis (Mtb) remains the leading single cause of death from bacterial infection. Here we explored the possibility of species-selective inhibition of lipoamide dehydrogenase (Lpd), an enzyme central to Mtb's intermediary metabolism and antioxidant defense. High-throughput screening of combinatorial chemical libraries identified triazaspirodimethoxybenzoyls as high-nanomolar inhibitors of Mtb's Lpd that were noncompetitive versus NADH, NAD(+), and lipoamide and >100-fold selective compared to human Lpd. Efficacy required the dimethoxy and dichlorophenyl groups. The structure of an Lpd-inhibitor complex was resolved to 2.42 A by X-ray crystallography, revealing that the inhibitor occupied a pocket adjacent to the Lpd NADH/NAD(+) binding site. The inhibitor did not overlap with the adenosine moiety of NADH/NAD(+) but did overlap with positions predicted to bind the nicotinamide rings in NADH and NAD(+) complexes. The dimethoxy ring occupied a deep pocket adjacent to the FAD flavin ring where it would block coordination of the NADH nicotinamide ring, while the dichlorophenyl group occupied a more exposed pocket predicted to coordinate the NAD(+) nicotinamide. Several residues that are not conserved between the bacterial enzyme and its human homologue were predicted to contribute both to inhibitor binding and to species selectivity, as confirmed for three residues by analysis of the corresponding mutant Mtb Lpd proteins. Thus, nonconservation of residues lining the electron-transfer tunnel in Mtb Lpd can be exploited for development of species-selective Lpd inhibitors.

Cooperation between a coenzyme A-independent stand-alone initiation module and an iterative type I polyketide synthase during synthesis of mycobacterial phenolic glycolipids

Several Mycobacterium tuberculosis strains, Mycobacterium leprae, and other mycobacterial pathogens produce a group of small-molecule virulence factors called phenolic glycolipids (PGLs). PGLs play key roles in pathogenicity and host−pathogen interaction. Thus, elucidation of the PGL biosynthetic pathway will not only expand our understanding of natural product biosynthesis, but may also illuminate routes to novel therapeutics to afford alternative lines of defense against mycobacterial infections. In this study, we report an investigation of the enzymatic requirements for the production of long-chain p-hydroxyphenylalkanoate intermediates of PGL biosynthesis. We demonstrate a functional cooperation between a coenzyme A-independent stand-alone didomain initiation module (FadD22) and a 6-domain reducing iterative type I polyketide synthase (Pks15/1) for production of p-hydroxyphenylalkanoate intermediates in in vitro and in vivo FadD22-Pks15/1 reconstituted systems. Our results suggest that Pks15/1 is an iterative type I polyketide synthase with a relaxed control of catalytic cycle iterations, a mechanistic property that explains the origin of a characteristic alkyl chain length variability seen in mycobacterial PGLs. The FadD22-Pks15/1 reconstituted systems lay an initial foundation for future efforts to unveil the mechanism of iterative catalysis control by which the structures of the final products of Pks15/1 are defined, and to scrutinize the functional partnerships of the FadD22-Pks15/1 system with downstream enzymes of the PGL biosynthetic pathway.

Synthetic carbohydrate-based anticancer vaccines: the Memorial Sloan-Kettering experience

Malignantly transformed cells can express aberrant cell surface glycosylation patterns, which serve to distinguish them from normal cells. This phenotype provides an opportunity for the development of carbohydrate-based vaccines for cancer immunotherapy. Synthetic carbohydrate-based vaccines, properly introduced through vaccination of a subject with a suitable construct, should be recognized by the immune system. Antibodies induced against these carbohydrate antigens could then participate in the eradication of carbohydrate-displaying tumor cells. Advances in carbohydrate synthetic capabilities have allowed us to efficiently prepare a range of complex, synthetic anticancer vaccine candidates. We describe herein the progression of our longstanding carbohydrate-based anticancer vaccine program, which is now at the threshold of clinical evaluation in several contexts. Our carbohydrate-based anticancer vaccine program has evolved through a number of stages: monomeric vaccines, monomeric clustered vaccines, unimolecular multi-antigenic vaccines and dual-acting vaccines. This account will focus on our recently developed unimolecular multi-antigenic constructs and potential dual-acting constructs, which contain clusters of both carbohydrate and peptide epitopes.

The heritability and genetics of frontotemporal lobar degeneration

BACKGROUND

Frontotemporal lobar degeneration (FTLD) is a genetically and pathologically heterogeneous neurodegenerative disorder.

METHODS

We collected blood samples from a cohort of 225 patients with a diagnosis within the FTLD spectrum and examined the heritability of FTLD by giving each patient a family history score, from 1 (a clear autosomal dominant history of FTLD) through to 4 (no family history of dementia). We also looked for mutations in each of the 5 disease-causing genes (MAPT, GRN, VCP, CHMP2B, and TARDP) and the FUS gene, known to cause motor neuron disease.

RESULTS

A total of 41.8% of patients had some family history (score of 1, 2, 3, or 3.5), although only 10.2% had a clear autosomal dominant history (score of 1). Heritability varied across the different clinical subtypes of FTLD with the behavioral variant being the most heritable and frontotemporal dementia-motor neuron disease and the language syndromes (particularly semantic dementia) the least heritable. Mutations were found in MAPT (8.9% of the cohort) and GRN (8.4%) but not in any of the other genes. Of the remaining patients without mutations but with a strong family history, 7 had pathologic confirmation, falling into 2 groups: type 3 FTLD-TDP without GRN mutations (6) and FTLD-UPS (1).

CONCLUSION

These findings show that frontotemporal lobar degeneration (FTLD) is a highly heritable disorder but heritability varies between the different syndromes. Furthermore, while MAPT and GRN mutations account for a substantial proportion of familial cases, there are other genes yet to be discovered, particularly in patients with type 3 FTLD-TDP without a GRN mutation.